Publications

Cable bacteria are filamentous, multicellular microorganisms that display an exceptional form of biological electron transport across centimeter-scale distances. Currents are guided through a network of nickel-containing protein fibers within the cell envelope. Still, the mechanism of long-range conduction remains unresolved. Here, we characterize the conductance of the fiber network under dry and wet, physiologically relevant, conditions. Our data reveal that the fiber conductivity is high (median value: 27 S cm−1; range: 2 to 564 S cm−1), does not show any redox signature, has a low thermal activation energy (Ea = 69 ± 23 meV), and is not affected by humidity or the presence of ions. These features set the nickel-based conduction mechanism in cable bacteria apart from other known forms of biological electron transport. As such, conduction resembles that of an organic semi-metal with a high charge carrier density. Our observation that biochemistry can synthesize an organo-metal-like structure opens the way for novel bio-based electronic technologies. © 2024 The Authors

JTD Keywords: 'current, Activation energy, Bacteria, Bioelectronic, Bioelectronics, Cable bacteria, Cables, Centimeter-scale, Electrochemical impedance spectroscopy, Electrochemical-impedance spectroscopies, Electron transport, Electron transport properties, Long-distance electron transport, Nickel, Nickel containing, Protein conductivity, Protein fibers, Proteins

The problems associated with the drugs currently used to treat leishmaniasis, including resistance, toxicity, and the high cost of some formulations, call for the urgent identification of new therapeutic agents with novel modes of action. The aggregated protein dye YAT2150 has been found to be a potent antileishmanial compound, with a half-maximal inhibitory concentration (IC50) of approximately 0.5 mu M against promastigote and amastigote stages of Leishmania infantum. The encapsulation in liposomes of YAT2150 significantly improved its in vitro IC50 to 0.37 and 0.19 mu M in promastigotes and amastigotes, respectively, and increased the half-maximal cytotoxic concentration in human umbilical vein endothelial cells to >50 mu M. YAT2150 became strongly fluorescent when binding intracellular protein deposits in Leishmania cells. This fluorescence pattern aligns with the proposed mode of action of this drug in the malaria parasite Plasmodium falciparum, the inhibition of protein aggregation. In Leishmania major, YAT2150 rapidly reduced ATP levels, suggesting an alternative antileishmanial mechanism. To the best of our knowledge, this first-in-class compound is the only one described so far having significant activity against both Plasmodium and Leishmania, thus being a potential drug for the treatment of co-infections of both parasites.

JTD Keywords: Animal, Animals, Antileishmanial drugs, Antiprotozoal agent, Antiprotozoal agents, Axenic amastigotes, Colocalization, Differentiation, Discovery, Endothelial cells, Endothelium cell, Human, Humans, Identification, Leishmania, Leishmania infantum, Leishmaniasis, Parasite, Parasites, Protein aggregation, Yat2150, Yeast

Factor XII (FXII) is a zymogen present in blood that tends to adsorb onto the surfaces of blood-contacting medical devices. Once adsorbed, it becomes activated, initiating a cascade of enzymatic reactions that lead to surface-induced coagulation. This process is characterized by multiple redundancies, making it extremely challenging to prevent clot formation and preserve the properties of the surface. In this study, a novel modulatory coating system based on C1-esterase inhibitor (C1INH) functionalized polymer brushes, which effectively regulates the activation of FXII is proposed. Using surface plasmon resonance it is demonstrated that this coating system effectively repels blood plasma proteins, including FXII, while exhibiting high activity against activated FXII and plasma kallikrein under physiological conditions. This unique property enables the modulation of FXII activation without interfering with the overall hemostasis process. Furthermore, through dynamic Chandler loop studies, it is shown that this coating significantly improves the hemocompatibility of polymeric surfaces commonly used in medical devices. By addressing the root cause of contact activation, the synergistic interplay between the antifouling polymer brushes and the modulatory C1INH is expected to lay the foundation to enhance the hemocompatibility of medical device surfaces.© 2023 The Authors. Macromolecular Bioscience published by Wiley-VCH GmbH.

JTD Keywords: adsorption, binding, c1-esterase-inhibitor, coatings, contact activation, factor-xii, fxii activation, hemocompatibility, hemocompatible surface modification, heparin, polymer brushes, system, thrombosis, Adsorption, Anticoagulation, Antifouling agent, Article, Beta-fxiia, Biocompatibility, Blood, Blood clotting, Blood clotting factor 12, Blood clotting factor 12a, Blood clotting factor 12a inhibitor, Blood coagulation, C1-esterase-inhibitor, Cell activation, Chemical activation, Coagulation, Coating (procedure), Complement component c1s inhibitor, Complement system, Controlled study, Dendrimers, Enzyme immobilization, Enzymes, Erythrocyte, Esters, Factor xii, Factor xii activation, Factor xiia, Fibrin deposition, Functional polymers, Fxii activation, Haemocompatibility, Hemocompatibility, Hemocompatible surface modification, Hemostasis, Heparin, Human, Hydrogel, Medical devices, Metabolism, Plasma kallikrein, Plasma protein, Plastic coatings, Platelet count, Polymer, Polymer brushes, Polymerization, Polymers, Property, Root cause, Surface plasmon resonance, Surface property, Surface reactions, Surface-modification, Thrombocyte adhesion, Β-fxiia

Conventional osteogenic platforms utilize active growth factors to repair bone defects that are extensive in size, but they can adversely affect patient health. Here, an unconventional osteogenic platform is reported that functions by promoting capture of inactive osteogenic growth factor molecules to the site of cell growth for subsequent integrin-mediated activation, using a recombinant fragment of latent transforming growth factor beta-binding protein-1 (rLTBP1). It is shown that rLTBP1 binds to the growth-factor- and integrin-binding domains of fibronectin on poly(ethyl acrylate) surfaces, which immobilizes rLTBP1 and promotes the binding of latency associated peptide (LAP), within which inactive transforming growth factor beta 1 (TGF-beta 1) is bound. rLTBP1 facilitates the interaction of LAP with integrin beta 1 and the subsequent mechanically driven release of TGF-beta 1 to stimulate canonical TGF-beta 1 signaling, activating osteogenic marker expression in vitro and complete regeneration of a critical-sized bone defect in vivo. An osteogenic platform that functions by capturing inactive growth factor molecules is engineered to overcome conventional challenges associated with the use of active growth factors. The platform triggers capture of inactive transforming growth factor beta-1 for its subsequent integrin-mediated activation which activates osteogenic downstream signaling in vitro and fully repairs critical-sized bone defect in vivo. image

JTD Keywords: Bone, Bone defect, Bone regeneration, Cell proliferation, Cells, Chemical activation, Defects, Differentiation, Fibronectin, Growth factor, Growth factors, Integrins, Latency associated peptides, Ltbp1, Osteogenic, Recombinant proteins, Release, Repair, Tgf-beta, Tgf-β1, Transforming growth factors

Interactions between living cells and nanoparticles are extensively studied to enhance the delivery of therapeutics. Nanoparticles size, shape, stiffness, and surface charge are regarded as the main features able to control the fate of cell-nanoparticle interactions. However, the clinical translation of nanotherapies has so far been limited, and there is a need to better understand the biology of cell-nanoparticle interactions. This study investigates the role of cellular mechanosensitive components in cell-nanoparticle interactions. It is demonstrated that the genetic and pharmacologic inhibition of yes-associated protein (YAP), a key component of cancer cell mechanosensing apparatus and Hippo pathway effector, improves nanoparticle internalization in triple-negative breast cancer cells regardless of nanoparticle properties or substrate characteristics. This process occurs through YAP-dependent regulation of endocytic pathways, cell mechanics, and membrane organization. Hence, the study proposes targeting YAP may sensitize triple-negative breast cancer cells to chemotherapy and increase the selectivity of nanotherapy.© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.

JTD Keywords: cancer treatment, cells, differentiation, hippo pathway, mechanics, mechanobiology, mechanotransduction, nanoparticles, progression, protein, resistance, yap-signaling, yap/taz, Adaptor proteins, signal transducing, Bio-nano interaction, Bio-nano interactions, Breast cancer cells, Cancer cells, Cancer treatment, Cells, Cellular therapeutics, Cellular uptake, Chemotherapy, Cytology, Diseases, Extracellular-matrix, Human, Humans, Mechano-biology, Mechanobiology, Metabolism, Nanoparticle, Nanoparticle interaction, Nanoparticles, Physiology, Protein serine threonine kinase, Protein serine-threonine kinases, Protein signaling, Signal transducing adaptor protein, Signal transduction, Therapeutic effects, Triple negative breast cancer, Triple negative breast neoplasms, Triple-negative breast cancers, Yap-signaling, Yes-associated protein-signaling

Human pluripotent stem cell -derived kidney organoids offer unprecedented opportunities for studying polycystic kidney disease (PKD), which still has no effective cure. Here, we developed both in vitro and in vivo organoid models of PKD that manifested tubular injury and aberrant upregulation of renin-angiotensin aldosterone system. Single -cell analysis revealed that a myriad of metabolic changes occurred during cystogenesis, including defective autophagy. Experimental activation of autophagy via ATG5 overexpression or primary cilia ablation significantly inhibited cystogenesis in PKD kidney organoids. Employing the organoid xenograft model of PKD, which spontaneously developed tubular cysts, we demonstrate that minoxidil, a potent autophagy activator and an FDA -approved drug, effectively attenuated cyst formation in vivo. This in vivo organoid model of PKD will enhance our capability to discover novel disease mechanisms and validate candidate drugs for clinical translation.

JTD Keywords: Adenylate kinase, Adult, Animal cell, Animal experiment, Animal model, Animal tissue, Article, Autophagosome, Autophagy, Autophagy (cellular), Autosomal-dominant, Calcium homeostasis, Cilia, Cilium, Cohort analysis, Controlled study, Cyclic amp, Disease, Dominant polycystic kidney, Enzyme linked immunosorbent assay, Epithelium, Exon, Expression, Female, Food and drug administration, Framework, Generation, Growth, Hepatitis a virus cellular receptor 1, Human, Human cell, Humans, Immunohistochemistry, In vitro study, In vivo study, Kidney, Kidney organoid, Kidney polycystic disease, Male, Minoxidil, Mouse, Mutations, Nonhuman, Organoid, Organoids, Platelet derived growth factor beta receptor, Pluripotent stem-cells, Polycystic kidney diseases, Protein kinase lkb1, Renin, Sequestosome 1, Single cell analysis, Single cell rna seq, Small nuclear rna, Tunel assay, Upregulation, Western blotting, Whole exome sequencing

Medical devices are crucial for patient care, yet even the best biomaterials lead to infections and unwanted activation of blood coagulation, potentially being life-threatening. While hydrophilic polymer brushes are the best coatings to mitigate these issues, their reliance on fossil raw materials underscores the urgency of bio-based alternatives. In this work, we introduce polymer brushes of a green solvent-based monomer, prohibiting protein adsorption, bacterial colonization, and blood clot formation at the same level as fossil-based polymer brushes. The polymer brushes are composed of N,N-dimethyl lactamide acrylate (DMLA), can be polymerized in a controlled manner, and show strong hydrophilicity as determined by thermodynamic analysis of the surface tension components. The contact of various challenging protein solutions results in repellency on the poly(DMLA) brushes. Furthermore, the poly(DMLA) brushes completely prevent the adhesion and colonization of Escherichia coli. Remarkably, upon blood contact, the poly(DMLA) brushes successfully prevent the formation of a fibrin network and leukocyte adhesion on the surface. While showcasing excellent antifouling properties similar to those of N-hydroxypropyl methacrylamide (HPMA) polymer brushes as one of the best antifouling coatings, the absence of hydroxyl groups prevents activation of the complement system in blood. We envision the polymer brushes to contribute to the future of hemocompatible coatings.

JTD Keywords: blood-plasma, coatings, contact, fossil, poly(2-methacryloyloxyethyl phosphorylcholine), protein adsorption, resistance, self-assembled monolayers, sulfobetaine, Surface-energy components

The immobilization of vesicles has been conceptualized as a method to functionalize biointerfaces. However, the preservation of their integrity post immobilization remains a considerable challenge. Interfacial interactions can cause vesicle rupture upon close surface contact and non-specific protein adsorption impairing surface functions. To date, immobilization of vesicles has relied solely on either entrapment or prior modification of vesicles, both of which require laborious preparation and limit their applications. This work develops a bioinspired strategy to pin vesicles without prior modification while preserving their intact shape. This work introduces antifouling diblock copolymers and ultrathin surface-attached hydrogels containing a brush-like interface consisting of a bottle brush copolymer of N-(2-hydroxypropyl) methacrylamide (HPMA) and N-(3-methacrylamidopropyl)-N,N-dimethyldodecan-1-aminiumiodide (C12+). The presence of positive charges generates an attractive force that pulls vesicles toward the surface. At the surface, the amphiphilic properties of the combs facilitate their insertion into the membrane, mimicking the harpooning mechanism observed in antimicrobial peptides. Importantly, the antifouling poly(HPMA) backdrop serves to safeguard the vesicles by preventing deformation and breakage. Using a combination of thermodynamic analysis, surface plasmon resonance, and confocal laser scanning microscopy, this work demonstrates the efficiency of this biomimetic system to capture vesicles while maintaining an antifouling interface necessary for bioapplications. This work presents a novel supramolecular approach that combines three key elements: long-range attraction, vesicle pinning, and short-range repulsion to attract and harpoon vesicles, while protecting them at the surface. This work envisions these coatings as universal and biocompatible platforms that can be used not only to study vesicle interactions, but also as tools for biomedical applications.image

JTD Keywords: Antifouling coatings, Coatings, Delivery, Extracellular vesicles, Fabrication, Hydrogel, Janus dendrimers, Lipid vesicles, Liposomes, Membrane insertion, Polymer brushes, Proteins, Surface-energy components, Ultrathin surface-attached hydrogels, Vesicle pinning

The cell nucleus plays a key role in cellular mechanoresponses. 3D genome organisation, gene expression, and cell behaviour, in general, are affected by mechanical force application to the nucleus, which is transmitted from the cellular environment via a network of interconnected cytoskeletal components. To effectively regulate cell responses, these cytoskeletal components must not only exert forces but also withstand external forces when necessary. This review delves into the latest research concerning how the cytoskeleton safeguards the nucleus from mechanical perturbations. Spe-cifically, we focus on the three primary cytoskeletal polymers: actin, intermediate filaments, and microtubules, as well as their interactions with the cell nucleus. We discuss how the cyto-skeleton acts as a protective shield for the nucleus, ensuring structural integrity and conveying context-specific mechanoresponses.

JTD Keywords: Actin, Architecture, Cytoskeleton, Envelope, F-actin, Filaments, Force, Genome, Intermediate filaments, Lamin, Mechanotransduction, Membrane protein, Microtubules, Nesprin-1, Nucleus

The mechanical properties of the extracellular matrix dictate tissue behaviour. In epithelial tissues, laminin is a very abundant extracellular matrix component and a key supporting element. Here we show that laminin hinders the mechanoresponses of breast epithelial cells by shielding the nucleus from mechanical deformation. Coating substrates with laminin-111-unlike fibronectin or collagen I-impairs cell response to substrate rigidity and YAP nuclear localization. Blocking the laminin-specific integrin β4 increases nuclear YAP ratios in a rigidity-dependent manner without affecting the cell forces or focal adhesions. By combining mechanical perturbations and mathematical modelling, we show that β4 integrins establish a mechanical linkage between the substrate and keratin cytoskeleton, which stiffens the network and shields the nucleus from actomyosin-mediated mechanical deformation. In turn, this affects the nuclear YAP mechanoresponses, chromatin methylation and cell invasion in three dimensions. Our results demonstrate a mechanism by which tissues can regulate their sensitivity to mechanical signals.© 2023. The Author(s).

JTD Keywords: actin, cell migration, filaments, force transmission, localization, membrane, motility, proteins, yap, Integrin alpha-6-beta-4

Fluorescent proteins, such as green fluorescent proteins, are invaluable tools for detecting and quantifying gene expression in high-throughput reporter gene assays. However, they introduce significant inaccuracies in studies involving microaerobiosis or anaerobiosis, as oxygen is required for the maturation of these proteins' chromophores. In this study, the authors highlight the errors incurred by using fluorescent proteins under limited oxygenation by comparing standard fluorescence-based reporter gene assays to quantitative real-time PCR data in the study of a complex oxygen-regulated gene network. Furthermore, a solution to perform quantification of anaerobic and microaerobic gene expression with fluorescent reporter proteins using a microplate reader with an oxygen control system and applying pulses of full oxygenation before fluorescence measurements is provided.

JTD Keywords: fluorescent proteins, gene expression, gfp, microaerobiosis, promoters, reporter gene assay, transcriptional fusion, Anaerobiosis, Fluorescent proteins, Gene expression, Gfp, Microaerobiosis, Pseudomonas-aeruginosa, Reporter gene assay, Transcriptional fusion

Clathrin-mediated endocytosis (CME) is an essential cellular process, conserved among eukaryotes. Yeast constitutes a powerful genetic model to dissect the complex endocytic machinery, yet there is a lack of specific pharmacological agents to interfere with CME in these organisms. TL2 is a light-regulated peptide inhibitor targeting the AP2-β-adaptin/β-arrestin interaction and that can photocontrol CME with high spatiotemporal precision in mammalian cells. Here, we study endocytic protein dynamics by live-cell imaging of the fluorescently tagged coat-associated protein Sla1-GFP, demonstrating that TL2 retains its inhibitory activity in S. cerevisiae spheroplasts. This is despite the β-adaptin/β-arrestin interaction not being conserved in yeast. Our data indicate that the AP2 α-adaptin is the functional target of activated TL2. We identified as interacting partners for the α-appendage, the Eps15 and epsin homologues Ede1 and Ent1. This demonstrates that endocytic cargo loading and sensing can be executed by conserved molecular interfaces, regardless of the proteins involved.© 2023 The Author(s).

JTD Keywords: adapters, alpha-appendage, azobenzene, cross-linker, mechanism, peptides, proteins, receptor, trafficking, Actin polymerization, Biochemistry, Biological sciences, Cell biology, Molecular biology, Natural sciences

The formation of a protein corona, where proteins spontaneously adhere to the surface of nanomaterials in biological environments, leads to changes in their physicochemical properties and subsequently affects their intended biomedical functionalities. Most current methods to study protein corona formation are ensemble-averaging and either require fluorescent labeling, washing steps, or are only applicable to specific types of particles. Here we introduce real-time all-optical nanoparticle analysis by scattering microscopy (RONAS) to track the formation of protein corona in full serum, at the single-particle level, without any labeling. RONAS uses optical scattering microscopy and enables real-time and in situ tracking of protein adsorption on metallic and dielectric nanoparticles with different geometries directly in blood serum. We analyzed the adsorbed protein mass, the affinity, and the kinetics of the protein adsorption at the single particle level. While there is a high degree of heterogeneity from particle to particle, the predominant factor in protein adsorption is surface chemistry rather than the underlying nanoparticle material or size. RONAS offers an in-depth understanding of the mechanisms related to protein coronas and, thus, enables the development of strategies to engineer efficient bionanomaterials.

JTD Keywords: Dielectric nanoparticles, Optical microscopy, Plasmonic nanoparticles, Protein corona, Protein corona,plasmonic nanoparticles,dielectricnanoparticles,optical microscopy,single particle, Silica nanoparticles,gold nanoparticles,surface-charge,adsorption,albumin,binding,size,transferrin,mas, Single particles

Charge exchange is the fundamental process that sustains cellular respiration and photosynthesis by shuttling electrons in a cascade of electron transfer (ET) steps between redox cofactors. While intraprotein charge exchange is well characterized in protein complexes bearing multiple redox sites, interprotein processes are less understood due to the lack of suitable experimental approaches and the dynamic nature of the interactions. Proteins constrained between electrodes are known to support electron transport (ETp) through the protein matrix even without redox cofactors, as the charges housed by the redox sites in ET are furnished by the electrodes. However, it is unknown whether protein ETp mechanisms apply to the interprotein medium present under physiological conditions. We study interprotein charge exchange between plant photosystem I (PSI) and its soluble redox partner plastocyanin (Pc) and address the role of the Pc copper center. Using electrochemical scanning tunneling spectroscopy (ECSTS) current-distance and blinking measurements, we quantify the spatial span of charge exchange between individual Pc/PSI pairs and ETp through transient Pc/PSI complexes. Pc devoid of the redox center (Pcapo) can exchange charge with PSI at longer distances than with the copper ion (Pcholo). Conductance bursts associated with Pcapo/PSI complex formation are higher than in Pcholo/PSI. Thus, copper ions are not required for long-distance Pc/PSI ETp but regulate its spatial span and conductance. Our results suggest that the redox center that carries the charge in Pc is not necessary to exchange it in interprotein ET through the aqueous solution and question the canonical view of tight complex binding between redox protein partners.

JTD Keywords: azurin, binding, blinking, crystal-structure, cupredoxin, current distance spectroscopy, electrochemical tunneling microscopy, proteinconductance, reduction, single metalloprotein, single molecule measurements, site, spectroscopy, Blinking, Cupredoxin, Current distance spectroscopy, Electrochemical tunneling microscopy, Interprotein electron transfer, Protein conductance, Single molecule measurements, State electron-transport

The small intestine is a complex organ with a characteristic architecture and a major site for drug and nutrient absorption. The three-dimensional (3D) topography organized in finger-like protrusions called villi increases surface area remarkably, granting a more efficient absorption process. The intestinal mucosa, where this process occurs, is a multilayered and multicell-type tissue barrier. In vitro intestinal models are routinely used to study different physiological and pathological processes in the gut, including compound absorption. Still, standard models are typically two-dimensional (2D) and represent only the epithelial barrier, lacking the cues offered by the 3D architecture and the stromal components present in vivo, often leading to inaccurate results. In this work, we studied the impact of the 3D architecture of the gut on drug transport using a bioprinted 3D model of the intestinal mucosa containing both the epithelial and the stromal compartments. Human intestinal fibroblasts were embedded in a previously optimized hydrogel bioink, and enterocytes and goblet cells were seeded on top to mimic the intestinal mucosa. The embedded fibroblasts thrived inside the hydrogel, remodeling the surrounding extracellular matrix. The epithelial cells fully covered the hydrogel scaffolds and formed a uniform cell layer with barrier properties close to in vivo. In particular, the villus-like model revealed overall increased permeability compared to a flat counterpart composed by the same hydrogel and cells. In addition, the efflux activity of the P-glycoprotein (P-gp) transporter was significantly reduced in the villus-like scaffold compared to a flat model, and the genetic expression of other drugs transporters was, in general, more relevant in the villus-like model. Globally, this study corroborates that the presence of the 3D architecture promotes a more physiological differentiation of the epithelial barrier, providing more accurate data on drug absorbance measurements.Copyright © 2023. Published by Elsevier B.V.

JTD Keywords: 3d architecture, alkaline-phosphatase, caco-2 cells, culture, drug development, efflux proteins, gene-expression, human-colon, intestinal absorption, intestinal models, microenvironment, paracellular transport, permeability, photopolymerization, villi, 3d architecture, 3d bioprinting, Drug development, In-vitro, Intestinal absorption, Intestinal models, Photopolymerization, Villi

As cells migrate and experience forces from their surroundings, they constantly undergo mechanical deformations which reshape their plasma membrane (PM). To maintain homeostasis, cells need to detect and restore such changes, not only in terms of overall PM area and tension as previously described, but also in terms of local, nanoscale topography. Here, we describe a novel phenomenon, by which cells sense and restore mechanically induced PM nanoscale deformations. We show that cell stretch and subsequent compression reshape the PM in a way that generates local membrane evaginations in the 100 nm scale. These evaginations are recognized by I-BAR proteins, which triggers a burst of actin polymerization mediated by Rac1 and Arp2/3. The actin polymerization burst subsequently re-flattens the evagination, completing the mechanochemical feedback loop. Our results demonstrate a new mechanosensing mechanism for PM shape homeostasis, with potential applicability in different physiological scenarios.© 2023, Quiroga et al.

JTD Keywords: arp2/3 complex, bar, bar proteins, cdc42, cells, domain, human, irsp53, membrane biophysics, mouse, proteins, rac, tension, Actin polymerization, Bar proteins, Cell biology, Human, Mechanobiology, Membrane biophysics, Mouse, Physics of living systems

The incorporation of exogenous lactate into cardiac tissues is a regenerative strategy that is rapidly gaining attention. In this work, two polymeric platforms were designed to achieve a sustained release of lactate, combining immediate and prolonged release profiles. Both platforms contained electrospun poly(lactic acid) (PLA) fibers and an alginate (Alg) hydrogel. In the first platform, named L/K(x)/Alg-PLA, lactate and proteinase K (x mg of enzyme per 1 g of PLA) were directly loaded into the Alg hydrogel, into which PLA fibers were assembled. In the second platform, L/Alg-K(x)/PLA, fibers were produced by electrospinning a proteinase K:PLA solution and, subsequently, assembled within the lactate-loaded hydrogel. After characterizing the chemical, morphological, and mechanical properties of the systems, as well as their cytotoxicity, the release profiles of the two platforms were determined considering different amounts of proteinase K (x = 5.2, 26, and 52 mg of proteinase K per 1 g of PLA), which is known to exhibit a broad cleavage activity. The profiles obtained using L/Alg-K(x)/PLA platforms with x = 26 and 52 were the closest to the criteria that must be met for cardiac tissue regeneration. Finally, the amount of lactate directly loaded in the Alg hydrogel for immediate release and the amount of protein in the electrospinning solution were adapted to achieve a constant lactate release of around 6 mM per day over 1 or 2 weeks. In the optimized bioplatform, in which 6 mM lactate was loaded in the hydrogel, the amount of fibers was increased by a factor of ×3, the amount of enzyme was adjusted to 40 mg per 1 g of PLA, and a daily lactate release of 5.9 ± 2.7 mM over a period of 11 days was achieved. Accordingly, the engineered device fully satisfied the characteristics and requirements for heart tissue regeneration.

JTD Keywords: biodegradable fibers, cardiac tissue regeneration, cell, drug-release, elastic-modulus, electrospinning, heart, nanoindentation, plasma treatment, proteinase, scaffold, stiffness, Alginate, Biodegradable fibers, Cardiac tissue regeneration, Electrospinning, Nanoindentation, Plasma treatment, Proteinase, Skeletal-muscle

JTD Keywords: nanocarriers, nucleic acid medicines, protein drugs, targeting, Biologics, Nanocarriers, Nucleic acid medicines, Protein drugs, Targeting

Gap junction channels (GJCs) mediate intercellular communication by connecting two neighbouring cells and enabling direct exchange of ions and small molecules. Cell coupling via connexin-43 (Cx43) GJCs is important in a wide range of cellular processes in health and disease (Churko and Laird, 2013; Liang et al., 2020; Poelzing and Rosenbaum, 2004), yet the structural basis of Cx43 function and regulation has not been determined until now. Here, we describe the structure of a human Cx43 GJC solved by cryo-EM and single particle analysis at 2.26 Å resolution. The pore region of Cx43 GJC features several lipid-like densities per Cx43 monomer, located close to a putative lateral access site at the monomer boundary. We found a previously undescribed conformation on the cytosolic side of the pore, formed by the N-terminal domain and the transmembrane helix 2 of Cx43 and stabilized by a small molecule. Structures of the Cx43 GJC and hemichannels (HCs) in nanodiscs reveal a similar gate arrangement. The features of the Cx43 GJC and HC cryo-EM maps and the channel properties revealed by molecular dynamics simulations suggest that the captured states of Cx43 are consistent with a closed state.© 2023, Qi, Acosta Gutierrez et al.

JTD Keywords: cryo-em, dehydroepiandrosterone dhea, expression, gap junction channel, gene, gja1 mutations, hemichannel, membrane protein, phenotype, protein, structure, system, visualization, Biochemistry, Chemical biology, Connexin-43, Cryo-em, Gap junction channel, Hemichannel, Human, Membrane protein, Molecular biophysics, Oculodentodigital dysplasia, Structural biology, Structure

The formation of a biological seal around the neck of titanium (Ti) implants is critical for ensuring integration at the gingival site and for preventing bacterial colonization that may lead to periimplantitis. This process is guided by activated fibroblasts, named myofibroblasts, which secrete extracellular matrix (ECM) proteins and ECM-degrading enzymes resolving the wound. However, in some cases, Ti is not able to attract and activate fibroblasts to a sufficient extent, which may compromise the success of the implant. Fibronectin (FN) is an ECM component found in wounds that is able to guide soft tissue healing through the adhesion of cells and attraction of growth factors (GFs). However, clinical use of FN functionalized Ti implants is problematic because FN is difficult to obtain, and is sensitive to degradation. Herein, functionalizing Ti with a modified recombinant heparin binding II (HBII) domain of FN, mutated to include an Arg-Gly-Asp (RGD) sequence for promoting both fibroblast adhesion and GF attraction, is aimed at. The HBII-RGD domain is able to stimulate fibroblast adhesion, spreading, proliferation, migration, and activation to a greater extent than the native HBII, reaching values closer to those of full-length FN suggesting that it might induce the formation of a biological sealing.© 2023 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH.

JTD Keywords: alpha-4-beta-1, beta, cell-binding, collagen, extracellular-matrix, fibroblast activation, fibronectin, growth factors, integrins, metalloproteinases, myofibroblasts, proliferation, soft-tissue integration, titanium, Biological-activities, Fibroblast activation, Titanium

Previous studies have shown hydrophilic/hydrophobic implant surfaces stimulate/hinder osseointegration. An analogous concept was applied here using common biological functional groups on a model surface to promote oral keratinocytes (OKs) proliferation and hemidesmosomes (HD) to extend implant lifespans through increased soft tissue attachment. However, it is unclear what physicochemistry stimulates HDs. Thus, common biological functional groups (NH2 , OH, and CH3 ) were functionalized on glass using silanization. Non-functionalized plasma-cleaned glass and H silanization were controls. Surface modifications were confirmed with X-ray photoelectron spectroscopy and water contact angle. The amount of bovine serum albumin (BSA) and fibrinogen, and BSA thickness, were assessed to understand how adsorbed protein properties were influenced by physicochemistry and may influence HDs. OKs proliferation was measured, and HDs were quantified with immunofluorescence for collagen XVII and integrin β4. Plasma-cleaned surfaces were the most hydrophilic group overall, while CH3 was the most hydrophobic and OH was the most hydrophilic among functionalized groups. Modification with the OH chemical group showed the highest OKs proliferation and HD expression. The OKs response on OH surfaces appeared to not correlate to the amount or thickness of adsorbed model proteins. These results reveal relevant surface physicochemical features to favor HDs and improve implant soft tissue attachment.© 2023 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals LLC.

JTD Keywords: attachment, chemistry, collagen, differentiation, epithelial-cells, hemidesmosome, implant, in-vitro, integrin, keratinocyte, mechanism, organosilane, physicochemistry, protein adsorption, Attachment, Cell-adhesion, Physicochemistry

Sprouting angiogenesis is a core biological process critical to vascular development. Its accurate simulation, relevant to multiple facets of human health, is of broad, interdisciplinary appeal. This study presents an in-silico model replicating a microfluidic assay where endothelial cells sprout into a biomimetic extracellular matrix, specifically, a large-pore, low-concentration fibrin-based porous hydrogel, influenced by chemotactic factors. We introduce a novel approach by incorporating the extracellular matrix and chemotactic factor effects into a unified term using a single parameter, primarily focusing on modelling sprouting dynamics and morphology. This continuous model naturally describes chemotactic-induced sprouting with no need for additional rules. In addition, we extended our base model to account for matrix sensing and degradation, crucial aspects of angiogenesis. We validate our model via a hybrid in-silico experimental method, comparing the model predictions with experimental results derived from the microfluidic setup. Our results underscore the intricate relationship between the extracellular matrix structure and angiogenic sprouting, proposing a promising method for predicting the influence of the extracellular matrix on angiogenesis.Copyright © 2023 Ferre-Torres, Noguera-Monteagudo, Lopez-Canosa, Romero-Arias, Barrio, Castaño and Hernandez-Machado.

JTD Keywords: angiogenesis, biomimmetic, chemotaxis, endothelial cells, filopodia, growth, in silico model, mathematical models, mechanisms, metalloproteinase, migration, morphogenesis, phase field, pore-size, simulation, Angiogenesis, Biomimmetic, Chemotaxis, Endothelial cells, Extracellular matrix, In silico model, Mathematical models, Phase field, Tip cells

Introduction: There is evidence that sample treatment of blood-based biosamples may affect integral signals in nuclear magnetic resonance-based metabolomics. The presence of macromolecules in plasma/serum samples makes investigating low-molecular-weight metabolites challenging. It is particularly relevant in the targeted approach, in which absolute concentrations of selected metabolites are often quantified based on the area of integral signals. Since there are a few treatments of plasma/serum samples for quantitative analysis without a universally accepted method, this topic remains of interest for future research. Methods: In this work, targeted metabolomic profiling of 43 metabolites was performed on pooled plasma to compare four methodologies consisting of Carr-Purcell-Meiboom-Gill (CPMG) editing, ultrafiltration, protein precipitation with methanol, and glycerophospholipid solid-phase extraction (g-SPE) for phospholipid removal; prior to NMR metabolomics analysis. The effect of the sample treatments on the metabolite concentrations was evaluated using a permutation test of multiclass and pairwise Fisher scores. Results: Results showed that methanol precipitation and ultrafiltration had a higher number of metabolites with coefficient of variation (CV) values above 20%. G-SPE and CPMG editing demonstrated better precision for most of the metabolites analyzed. However, differential quantification performance between procedures were metabolite-dependent. For example, pairwise comparisons showed that methanol precipitation and CPMG editing were suitable for quantifying citrate, while g-SPE showed better results for 2-hydroxybutyrate and tryptophan. Discussion: There are alterations in the absolute concentration of various metabolites that are dependent on the procedure. Considering these alterations is essential before proceeding with the quantification of treatment-sensitive metabolites in biological samples for improving biomarker discovery and biological interpretations. The study demonstrated that g-SPE and CPMG editing are effective methods for removing proteins and phospholipids from plasma samples for quantitative NMR analysis of metabolites. However, careful consideration should be given to the specific metabolites of interest and their susceptibility to the sample treatment procedures. These findings contribute to the development of optimized sample preparation protocols for metabolomics studies using NMR spectroscopy.Copyright © 2023 Madrid-Gambin, Oller, Marco, Pozo, Andres-Lacueva and Llorach.

JTD Keywords: binding, h-1-nmr spectroscopy, human serum, lactate, metabolites, nuclear magnetic resonance, plasma, protein, quantification, quantitative analysis, sample treatment, Metabolomics, Nuclear magnetic resonance, Nuclear-magnetic-resonance, Plasma, Quantification, Quantitative analysis, Sample treatment

(Phospho)proteomics of old-aged subjects without cognitive or behavioral symptoms, and without AD-neuropathological changes and lacking any other neurodegenerative alteration will increase understanding about the physiological state of human brain aging without associate neurological deficits and neuropathological lesions.(Phospho)proteomics using conventional label-free- and SWATH-MS (Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry) has been assessed in the frontal cortex (FC) of individuals without NFTs, senile plaques (SPs) and age-related co-morbidities classified by age (years) in four groups; group 1 (young, 30-44); group 2 (middle-aged: MA, 45-52); group 3 (early-elderly, 64-70); and group 4 (late-elderly, 75-85).Protein levels and deregulated protein phosphorylation linked to similar biological terms/functions, but involving different individual proteins, are found in FC with age. The modified expression occurs in cytoskeleton proteins, membranes, synapses, vesicles, myelin, membrane transport and ion channels, DNA and RNA metabolism, ubiquitin-proteasome-system (UPS), kinases and phosphatases, fatty acid metabolism, and mitochondria. Dysregulated phosphoproteins are associated with the cytoskeleton, including microfilaments, actin-binding proteins, intermediate filaments of neurons and glial cells, and microtubules; membrane proteins, synapses, and dense core vesicles; kinases and phosphatases; proteins linked to DNA and RNA; members of the UPS; GTPase regulation; inflammation; and lipid metabolism. Noteworthy, protein levels of large clusters of hierarchically-related protein expression levels are stable until 70. However, protein levels of components of cell membranes, vesicles and synapses, RNA modulation, and cellular structures (including tau and tubulin filaments) are markedly altered from the age of 75. Similarly, marked modifications occur in the larger phosphoprotein clusters involving cytoskeleton and neuronal structures, membrane stabilization, and kinase regulation in the late elderly.Present findings may increase understanding of human brain proteostasis modifications in the elderly in the subpopulation of individuals not having AD neuropathological change and any other neurodegenerative change in any telencephalon region.

JTD Keywords: (phospho)proteomics, cortex, cytoskeleton, hippocampus, kinases, membranes, mitochondria, mitochondrial-function, pathological process, phosphoproteome analysis, phosphorylation, proteome, quantitative proteomics, synapsis, tau-protein, therapeutic target, (phospho)proteomics, Brain aging, Cytoskeleton, Kinases, Membranes, Mitochondria, Neurodegenerative diseases, Proteome, Synapsis

The hippocampus of cases with neurofibrillary tangles (NFT) pathology classified as stages I–II, III–IV, and V–VI without comorbidities, and middle-aged (MA) individuals with no NFT pathology, were examined to learn about the composition of granulovacuolar degeneration (GVD). Our results confirm the presence of CK1-?, p38-P Thr180/Tyr182, SAPK/JNK-P Thr183/Thr185, GSK-3?/?-P Tyr279/Tyr216, and GSK-3? Ser9 in the cytoplasmic granules in a subset of neurons of the CA1 and CA2 subfields of the hippocampus. Also, we identify the presence of PKA ?/?-P Thr197, SRC-P Tyr416, PAK1-P Ser199/Ser204, CAMK2A-P Tyr197, and PKCG-P Thr655 in cytoplasmic granules in cases with NFT pathology, but not in MA cases. Our results also confirm the presence of ?-catenin-P Ser45/Thr41, IRE?-P Ser274, eIF2?-P Ser51, TDP-43-P Ser403-404 (but absent TDP-43), and ubiquitin in cytoplasmic granules. Other components of the cytoplasmic granules are MAP2-P Thr1620/1623, MAP1B-P Thr1265, ADD1-P Ser726, and ADD1/ADD1-P Ser726/Ser713, in addition to several tau species including 3Rtau, 4Rtau, and tau-P Ser262. The analysis of GVD at progressive stages of NFT pathology reveals the early appearance of phosphorylated kinases and proteins in cytoplasmic granules at stages I–II, before the appearance of pre-tangles and NFTs. Most of these granules are not surrounded by LAMP1-positive membranes. Markers of impaired ubiquitin-protesome system, abnormal reticulum stress response, and altered endocytic and autophagic pathways occur in a subpopulation of neurons containing cytoplasmic granules, and they appear later. These observations suggest early phosphorylation of kinases leading to their activation, and resulting in the abnormal phosphorylation of various substrates, including tau, as a main alteration at the first stages of GVD. © 2021 The Author(s)

JTD Keywords: alzheimer's disease, alzheimers association guidelines, alzheimer’s disease, brain aging, cyclin-dependent kinase-5, granulovacuolar degeneration, kinases, national institute, neuropathologic assessment, p38 kinase, progressive supranuclear palsy, protein phosphorylation, tau, tau pathology, up-regulation, upstream activator, Alzheimer's disease, Brain aging, Glycogen-synthase kinase-3, Granulovacuolar degeneration, Kinases, Protein phosphorylation, Tau

Here we revisit tau protein aggregation at primary, secondary, tertiary and quaternary structures. In addition, the presence of non-aggregated tau protein, which has been recently discovered, is also commented on.Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.

JTD Keywords: alpha-helix, alzheimer-disease, antigenic determinants, binding, isomerase pin1, microtubule-binding repeats, neurofibrillary tangles, paired helical filaments, repeat domain, structural-characterization, tau conformations, w-tau isoform, Microtubule-associated protein, Microtubule-binding repeats, Tau, Tau conformations, W-tau isoform

Despite the high homology of OmpF and OmpC, the internally folded loop responds differently to temperature increase.

JTD Keywords: diffusion, mechanism, molecules, nanopores, permeability, proteins, rules, simulations, transport, Membrane

JTD Keywords: deep generative models, eatris european infrastructure for translational medicine, integrative omics, machine learning, multi-omics, personalized medicine, Deep generative models, Eatris european infrastructure for translational medicine, Integrative omics, Machine learning, Multi-omics, Personalized medicine, Protein protein interaction (ppi) network

The symptoms of Myotonic Dystrophy Type 1 (DM1) are multi-systemic and life-threatening. The neuromuscular disorder is rooted in a non-coding CTG microsatellite expansion in the DM1 protein kinase (DMPK) gene that, upon transcription, physically sequesters the Muscleblind-like (MBNL) family of splicing regulator proteins. The high-affinity binding occurring between the proteins and the repetitions disallow MBNL proteins from performing their post-transcriptional splicing regulation leading to downstream molecular effects directly related to disease symptoms such as myotonia and muscle weakness. In this study, we build on previously demonstrated evidence showing that the silencing of miRNA-23b and miRNA-218 can increase MBNL1 protein in DM1 cells and mice. Here, we use blockmiR antisense technology in DM1 muscle cells, 3D mouse-derived muscle tissue, and in vivo mice to block the binding sites of these microRNAs in order to increase MBNL translation into protein without binding to microRNAs. The blockmiRs show therapeutic effects with the rescue of mis-splicing, MBNL subcellular localization, and highly specific transcriptomic expression. The blockmiRs are well tolerated in 3D mouse skeletal tissue inducing no immune response. In vivo, a candidate blockmiR also increases Mbnl1/2 protein and rescues grip strength, splicing, and histological phenotypes.

JTD Keywords: antisense oligonucleotides, aon, blockmir, brain, expression, genes, mbnl, mir-218, mir-23b, mirna, muscleblind, myotonic dystrophy 1, phenotypes, proteins, type-1, Messenger-rna, Muscleblind, Myotonic dystrophy 1

Transcriptomics and phosphoproteomics were carried out in the cerebral cortex of B6.Cg-Mapttm1(EGFP)Klt (tau knockout: tau-KO) and wild-type (WT) 12 month-old mice to learn about the effects of tau ablation. Compared with WT mice, tau-KO mice displayed reduced anxiety-like behavior and lower fear expression induced by aversive conditioning, whereas recognition memory remained unaltered. Cortical transcriptomic analysis revealed 69 downregulated and 105 upregulated genes in tau-KO mice, corresponding to synaptic structures, neuron cytoskeleton and transport, and extracellular matrix components. RT-qPCR validated increased mRNA levels of col6a4, gabrq, gad1, grm5, grip2, map2, rab8a, tubb3, wnt16, and an absence of map1a in tau-KO mice compared with WT mice. A few proteins were assessed with Western blotting to compare mRNA expression with corresponding protein levels. Map1a mRNA and protein levels decreased. However, β-tubulin III and GAD1 protein levels were reduced in tau-KO mice. Cortical phosphoproteomics revealed 121 hypophosphorylated and 98 hyperphosphorylated proteins in tau-KO mice. Deregulated phosphoproteins were categorized into cytoskeletal (n = 45) and membrane proteins, including proteins of the synapses and vesicles, myelin proteins, and proteins linked to membrane transport and ion channels (n = 84), proteins related to DNA and RNA metabolism (n = 36), proteins connected to the ubiquitin-proteasome system (UPS) (n = 7), proteins with kinase or phosphatase activity (n = 21), and 22 other proteins related to variegated pathways such as metabolic pathways, growth factors, or mitochondrial function or structure. The present observations reveal a complex altered brain transcriptome and phosphoproteome in tau-KO mice with only mild behavioral alterations.

JTD Keywords: computational platform, conformational-changes, cytoskeleton, disease, expression, isoforms, mechanisms, mice, phosphoproteomics, phosphorylation, synapse, tau-ko, tauopathies, transcriptomics, Tau-ko, Tau-protein, Transcriptomics

Drug and gene delivery systems based on polymeric nanoparticles offer a greater efficacy and a reduced toxicity compared to traditional formulations. Recent studies have evidenced that their internalization, biodistribution and efficacy can be affected, among other factors, by their mechanical properties. Here, we analyze by means of Atomic Force Microscopy force spectroscopy how composition, surface functionalization and loading affect the mechanics of nanoparticles. For this purpose, nanoparticles made of Poly(lactic-co-glycolic) (PLGA) and Ethyl cellulose (EC) with different functionalizations and loading were prepared by nano-emulsion templating using the Phase Inversion Composition method (PIC) to form the nano-emulsions. A multiparametric nanomechanical study involving the determination of the Young's modulus, maximum deformation and breakthrough force was carried out. The obtained results showed that composition, surface functionalization and loading affect the nanomechanical properties in a different way, thus requiring, in general, to consider the overall mechanical properties after the addition of a functionalization or loading. A graphical representation method has been proposed enabling to easily identify mechanically equivalent formulations, which is expected to be useful in the development of soft polymeric nanoparticles for pre-clinical and clinical use.Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.

JTD Keywords: afm, atomic-force microscopy, cell, delivery-systems, drug-delivery, emulsification approach, internalization, mechanics of nanoparticles, nanomedicine, nanoparticle functionalization, particles, protein corona, size, young?s modulus, Afm, Loaded plga nanoparticles, Mechanics of nanoparticles, Nanomedicine, Nanoparticle functionalization, Polymeric nanoparticles, Young’s modulus

Many lines of evidence demonstrate a correlation between liver glycogen content and food intake. We previously demonstrated that mice overexpressing protein targeting to glycogen (PTG) specifically in the liver—which have increased glycogen content in this organ—are protected from high-fat diet (HFD)-induced obesity by reduced food intake. However, the use of PTG to increase liver glycogen implies certain limitations. PTG stimulates glycogen synthesis but also inhibits the enzyme responsible for glycogen degradation. Furthermore, as PTG is a regulatory subunit of protein phosphatase 1 (PP1), which regulates many cellular functions, its overexpression could have side effects beyond the regulation of glycogen metabolism. Therefore, it is necessary to determine whether the direct activation of glycogen synthesis, without affecting its degradation or other cellular functions, has the same effects. To this end, we generated mice overexpressing a non-inactivatable form of glycogen synthase (GS) specifically in the liver (9A-MGSAlb mice). Control and 9a-MGSAlb mice were fed a standard diet (SD) or HFD for 16 weeks. Glucose tolerance and feeding behavior were analyzed. 9A-MGSAlb mice showed an increase in hepatic glycogen in fed and fasting conditions. When fed an HFD, these animals preserved their hepatic energy state, had a reduced food intake, and presented a lower body weight and fat mass than control animals, without changes in energy expenditure. Furthermore, 9A-MGSAlb animals showed improved glucose tolerance when fed an SD or HFD. Moreover, liver triacylglycerol levels that were increased after HFD feeding were lower in these mice. These results confirm that increased liver glycogen stores contribute to decreased appetite and improve glucose tolerance in mice fed an HFD. On the basis of our findings, strategies to preserve hepatic glycogen stores emerge as potential treatments for obesity and hyperglycemia.

JTD Keywords: accumulation, atp, attenuates obesity, expression, food intake, glucose, glycogen, glycogen synthase, high-fat diet, homeostasis, hyperglycemia, liver, mgat1, muscle, protein, ptg, Glycogen, Hepatic overexpression, Liver

Prion-like domains (PrLDs) are intrinsically disordered regions (IDRs) of low sequence complexity with a similar composition to yeast prion domains. PrLDs-containing proteins have been involved in different organisms' regulatory processes. Regions of moderate amyloid propensity within IDRs have been shown to assemble autonomously into amyloid fibrils. These sequences tend to be rich in polar amino acids and often escape from the detection of classical bioinformatics screenings that look for highly aggregation-prone hydrophobic sequence stretches. We defined them as cryptic amyloidogenic regions (CARs) and recently developed an integrated database that collects thousands of predicted CARs in IDRs. CARs seem to be evolutionary conserved among disordered regions because of their potential to stablish functional contacts with other biomolecules. Here we have focused on identifying and characterizing CARs in prion-like proteins (pCARs) from plants, a lineage that has been poorly studied in comparison with other prionomes. We confirmed the intrinsic amyloid potential for a selected pCAR from Arabidopsis thaliana and explored functional enrichments and compositional bias of pCARs in plant prion-like proteins.Copyright © 2023 Pintado-Grima, Santos, Iglesias, Manglano-Artuñedo, Pallarès and Ventura.

JTD Keywords: aggregation, aromatic residues, bioinformatics, domains, functional interactions, identify proteins, plants, prediction, prion-like domains, q/n-rich, regulator, sup35, yeast, Bioinformatics, Cryptic amyloidogenic regions, Functional interactions, Plants, Prion-like domains, Rna-binding proteins

Mechanical force modulates the conformation and function of individual proteins, and this underpins many mechanically driven cellular processes. This Review addresses single-molecule force spectroscopy experiments conducted on proteins with a known role in mechanosensing and mechanotransduction in eukaryotic cells.; In addition to biochemical signals and genetic considerations, mechanical forces are rapidly emerging as a master regulator of human physiology. However, the molecular mechanisms that regulate force-induced functionalities across a wide range of scales, encompassing the cell, tissue or organ levels, are not well understood in comparison. With the advent, development and refining of single-molecule nanomechanical techniques that enable the conformational dynamics of individual proteins under the effect of a calibrated force to be probed, we have begun to acquire a comprehensive knowledge of the diverse physicochemical principles that regulate the elasticity of single proteins. Here, we review the major advances underpinning our current understanding of how the elasticity of single proteins regulates mechanosensing and mechanotransduction. We discuss the present limitations and future challenges of this prolific and burgeoning field.

JTD Keywords: Cadherin adhesion, Energy landscape, Extracellular-matrix protein, Focal adhesion kinase, Mechanical stability, Molecule force spectroscopy, Muscle protein, N2b element, Stranded-dna, Structural basis

The properties of nanoparticles (NPs) can change upon contact with serum components, occluding the NP surface by forming a biomolecular corona. It is believed that targeted NPs can lose their functionality due to this biological coating, thus losing specificity and selectivity toward target cells and leading to poor therapeutic efficiency. A better understanding of how the biomolecular corona affects NP ligand functionality is needed to maintain NP targeting capabilities. However, techniques that can quantify the functionality of NPs at a single-particle level in a complex medium are limited and often laborious in sample preparation, measurement, and analysis. In this work, the influence of serum exposure on the functionality of antibody-functionalized NPs was quantified using a straightforward total internal reflection fluorescence (TIRF) microscopy method and evaluated in cell uptake studies. The single-particle resolution of TIRF reveals the interparticle functionality heterogeneity and the substantial differences between NPs conjugated with covalent and noncovalent methods. Notably, only NPs covalently conjugated with a relatively high amount of antibodies maintain their functionality to a certain extent and still showed cell specificity and selectivity toward high receptor density cells after incubation in full serum. The presented study emphasizes the importance of single-particle functional characterization of NPs in complex media, contributing to the understanding and design of targeted NPs that retain their cell specificity and selectivity in biologically relevant conditions.

JTD Keywords: binding, biomolecular corona, cell selectivity, heterogeneity, nanoparticle conjugation, protein corona, tirf microscopy, Active targeting, Biomolecular corona, Cell selectivity, Heterogeneity, Nanoparticle conjugation, Tirf microscopy

Heterozygous hTau mice were used for the study of tau seeding. These mice express the six human tau isoforms, with a high predominance of 3Rtau over 4Rtau. The following groups were assessed: (i) non-inoculated mice aged 9 months (n = 4); (ii) Alzheimer's Disease (AD)-inoculated mice (n = 4); (iii) Globular Glial Tauopathy (GGT)-inoculated mice (n = 4); (iv) Pick's disease (PiD)-inoculated mice (n = 4); (v) control-inoculated mice (n = 4); and (vi) inoculated with vehicle alone (n = 2). AD-inoculated mice showed AT8-immunoreactive neuronal pre-tangles, granular aggregates, and dots in the CA1 region of the hippocampus, dentate gyrus (DG), and hilus, and threads and dots in the ipsilateral corpus callosum. GGT-inoculated mice showed unique or multiple AT8-immunoreactive globular deposits in neurons, occasionally extended to the proximal dendrites. PiD-inoculated mice showed a few loose pre-tangles in the CA1 region, DG, and cerebral cortex near the injection site. Coiled bodies were formed in the corpus callosum in AD-inoculated mice, but GGT-inoculated mice lacked globular glial inclusions. Tau deposits in inoculated mice co-localized active kinases p38-P and SAPK/JNK-P, thus suggesting active phosphorylation of the host tau. Tau deposits were absent in hTau mice inoculated with control homogenates and vehicle alone. Deposits in AD-inoculated hTau mice contained 3Rtau and 4Rtau; those in GGT-inoculated mice were mainly stained with anti-4Rtau antibodies, but a small number of deposits contained 3Rtau. Deposits in PiD-inoculated mice were stained with anti-3Rtau antibodies, but rare neuronal, thread-like, and dot-like deposits showed 4Rtau immunoreactivity. These findings show that tau strains produce different patterns of active neuronal seeding, which also depend on the host tau. Unexpected 3Rtau and 4Rtau deposits after inoculation of homogenates from 4R and 3R tauopathies, respectively, suggests the regulation of exon 10 splicing of the host tau during the process of seeding, thus modulating the plasticity of the cytoskeleton.

JTD Keywords: alzheimer's disease (ad), alzheimers-disease, brain, corticobasal degeneration, globular glial tauopathy (ggt), htau, isoforms, pathological tau, pick's disease (pid), picks-disease, propagation, protein, seeding, tau splicing, tauopathy, Alzheimer’s disease (ad), Globular glial tauopathy (ggt), Htau, Paired helical filaments, Pick’s disease (pid), Seeding, Tau, Tau splicing

Abstract Oxidative stress, which occurs when an organism is exposed to an adverse stimulus that results in a misbalance of antioxidant and pro-oxidants species, is the common denominator of diseases considered as a risk factor for SARS-CoV-2 lethality. Indeed, reactive oxygen species caused by oxidative stress have been related to many virus pathogenicity. In this work, simulations have been performed on the receptor binding domain of SARS-CoV-2 spike glycoprotein to study what residues are more susceptible to be attacked by ·OH, which is one of the most reactive radicals associated to oxidative stress. The results indicate that isoleucine (ILE) probably plays a crucial role in modification processes driven by radicals. Accordingly, QM/MM-MD simulations have been conducted to study both the ·OH-mediated hydrogen abstraction of ILE residues and the induced modification of the resulting ILE radical through hydroxylation or nitrosylation reactions. All in all, in silico studies show the importance of the chemical environment triggered by oxidative stress on the modifications of the virus, which is expected to help for foreseeing the identification or development of antioxidants as therapeutic drugs. Graphic abstract

JTD Keywords: atom abstraction, damage, density functionals, hydrogen abstraction, isoleucine, molecular dynamics, pathogenesis, protein, reactive oxygen species, receptor binding domain, residues, spike protein, Amino-acids, Hydrogen abstraction, Isoleucine, Molecular dynamics, Reactive oxygen species, Receptor binding domain, Spike protein

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the “device”/epithelium interface, serve as exquisite examples to inspire longer lasting long-term percutaneous device design. For example, the tooth's imperviousness to infection is mediated by the epithelium directly surrounding it, the junctional epithelium (JE). The hallmark feature of JE is formation of hemidesmosomes, cell/matrix adhesive structures that attach surrounding oral gingiva to the tooth's enamel through a basement membrane. Here, the authors survey the multifaceted functions of the JE, emphasizing the role of the matrix, with a particular focus on hemidesmosomes and their five main components. The authors highlight the known (and unknown) effects dental implant – as a model percutaneous device – placement has on JE regeneration and synthesize this information for application to other percutaneous devices. The authors conclude with a summary of bioengineering strategies aimed at solving the percutaneous device dilemma and invigorating greater collaboration between clinicians, bioengineers, and matrix biologists. © 2022 The Authors

JTD Keywords: amino-acid-sequence, bioinspired surfaces, cell-secreted protein, growth-factor receptor, hemidesmosome, integrin beta-4 subunit, junctional epithelium, keratinocyte-derived chemokine, laminin-binding integrins, marginal bone loss, percutaneous device, percutaneous implant, pressure wound therapy, soft-tissue integration, Bioinspired surfaces, Bullous-pemphigoid antigen, Hemidesmosome, Junctional epithelium, Percutaneous device, Percutaneous implant

Building functional mimics of cell membranes is an important task toward the development of synthetic cells. So far, lipid and amphiphilic block copolymers are the most widely used amphiphiles with the bilayers by the former lacking stability while membranes by the latter are typically characterized by very slow dynamics. Herein, we introduce a new type of Janus dendrimer containing a zwitterionic phosphocholine hydrophilic headgroup (JDPC ) and a 3,5-substituted dihydrobenzoate-based hydrophobic dendron. JDPC self-assembles in water into zwitterionic dendrimersomes (z-DSs) that faithfully recapitulate the cell membrane in thickness, flexibility, and fluidity, while being resilient to harsh conditions and displaying faster pore closing dynamics in the event of membrane rupture. This enables the fabrication of hybrid DSs with components of natural membranes, including pore-forming peptides, structure-directing lipids, and glycans to create raft-like domains or onion vesicles. Moreover, z-DSs can be used to create active synthetic cells with life-like features that mimic vesicle fusion and motility as well as environmental sensing. Despite their fully synthetic nature, z-DSs are minimal cell mimics that can integrate and interact with living matter with the programmability to imitate life-like features and beyond. This article is protected by copyright. All rights reserved.This article is protected by copyright. All rights reserved.

JTD Keywords: biological-membranes, bottom-up synthetic biology, chain, hybrid vesicles, hydroethidine, organization, polymersome, proteins, stability, synthetic cells, thickness, vesicle fusion, vesicle motility, vesicles, zwitterionic dendrimersomes, Biosensor, Biosensors, Bottom-up synthetic biology, Hybrid vesicles, Lipid-bilayers, Synthetic cells, Vesicle fusion, Vesicle motility, Zwitterionic dendrimersomes

Tissue engineering is nowadays a powerful tool to restore damaged tissues and recover their normal functionality. Advantages over other current methods are well established, although a continuous evolution is still necessary to improve the final performance and the range of applications. Trends are nowadays focused on the development of multifunctional scaffolds with hierarchical structures and the capability to render a sustained delivery of bioactive molecules under an appropriate stimulus. Nanocomposites incorporating hydroxyapatite nanoparticles (HAp NPs) have a predominant role in bone tissue regeneration due to their high capacity to enhance osteoinduction, osteoconduction, and osteointegration, as well as their encapsulation efficiency and protection capability of bioactive agents. Selection of appropriated polymeric matrices is fundamental and consequently great efforts have been invested to increase the range of properties of available materials through copolymerization, blending, or combining structures constituted by different materials. Scaffolds can be obtained from different processes that differ in characteristics, such as texture or porosity. Probably, electrospinning has the greater relevance, since the obtained nanofiber membranes have a great similarity with the extracellular matrix and, in addition, they can easily incorporate functional and bioactive compounds. Coaxial and emulsion electrospinning processes appear ideal to generate complex systems able to incorporate highly different agents. The present review is mainly focused on the recent works performed with Hap-loaded scaffolds having at least one structural layer composed of core/shell nanofibers.

JTD Keywords: bone tissue, coaxial electrospinning, composite nanofibers, drug-release behavior, emulsion electrospinning, hydroxyapatite, in-vitro evaluation, mechanical-properties, osteogenic differentiation, pickering emulsions, protein adsorption, structured scaffolds, surface-initiated polymerization, tissue regeneration, Bone tissue, Coaxial electrospinning, Emulsion electrospinning, Hydroxyapatite, Multifunctional scaffolds, Poly(3-hydroxybutyrate) phb patches, Tissue regeneration

Multiplexed assays of variant effects (MAVEs) guide clinical variant interpretation and reveal disease mechanisms. To date, MAVEs have focussed on a single mutation type-amino acid (AA) substitutions-despite the diversity of coding variants that cause disease. Here we use Deep Indel Mutagenesis (DIM) to generate a comprehensive atlas of diverse variant effects for a disease protein, the amyloid beta (Aβ) peptide that aggregates in Alzheimer's disease (AD) and is mutated in familial AD (fAD). The atlas identifies known fAD mutations and reveals that many variants beyond substitutions accelerate Aβ aggregation and are likely to be pathogenic. Truncations, substitutions, insertions, single- and internal multi-AA deletions differ in their propensity to enhance or impair aggregation, but likely pathogenic variants from all classes are highly enriched in the polar N-terminal region of Aβ. This comparative atlas highlights the importance of including diverse mutation types in MAVEs and provides important mechanistic insights into amyloid nucleation.© 2022. The Author(s).

JTD Keywords: amyloid-beta(1-42), determinants, disease, mutants, protein, secondary nucleation, Atomic-resolution structure

Around 30-40% of patients with colorectal cancer (CRC) undergoing curative resection of the primary tumour will develop metastases in the subsequent years1. Therapies to prevent disease relapse remain an unmet medical need. Here we uncover the identity and features of the residual tumour cells responsible for CRC relapse. An analysis of single-cell transcriptomes of samples from patients with CRC revealed that the majority of genes associated with a poor prognosis are expressed by a unique tumour cell population that we named high-relapse cells (HRCs). We established a human-like mouse model of microsatellite-stable CRC that undergoes metastatic relapse after surgical resection of the primary tumour. Residual HRCs occult in mouse livers after primary CRC surgery gave rise to multiple cell types over time, including LGR5+ stem-like tumour cells2-4, and caused overt metastatic disease. Using Emp1 (encoding epithelial membrane protein 1) as a marker gene for HRCs, we tracked and selectively eliminated this cell population. Genetic ablation of EMP1high cells prevented metastatic recurrence and mice remained disease-free after surgery. We also found that HRC-rich micrometastases were infiltrated with T cells, yet became progressively immune-excluded during outgrowth. Treatment with neoadjuvant immunotherapy eliminated residual metastatic cells and prevented mice from relapsing after surgery. Together, our findings reveal the cell-state dynamics of residual disease in CRC and anticipate that therapies targeting HRCs may help to avoid metastatic relapse.© 2022. The Author(s), under exclusive licence to Springer Nature Limited.

JTD Keywords: colonization, defines, human colon, mutations, plasticity, retrieval, stem-cells, subtypes, underlie, Animal, Animal cell, Animal experiment, Animal model, Animal tissue, Animals, Article, Cancer, Cancer growth, Cancer immunotherapy, Cancer inhibition, Cancer recurrence, Cancer staging, Cell, Cell adhesion, Cell migration, Cell population, Cell surface receptor, Cohort analysis, Colorectal cancer, Colorectal neoplasms, Colorectal tumor, Comprehensive molecular characterization, Controlled study, Crispr-cas9 system, Cytoskeleton, Disease exacerbation, Disease progression, Dynamics, Emp1 gene, Epithelial membrane protein-1, Extracellular matrix, Flow cytometry, Fluorescence intensity, Gene expression, Genetics, Human, Human cell, Humans, Immune response, Immunofluorescence, In situ hybridization, Marker gene, Metastasis potential, Mice, Minimal residual disease, Mouse, Neoplasm proteins, Neoplasm recurrence, local, Neoplasm, residual, Nonhuman, Pathology, Phenotype, Prevention and control, Protein, Receptors, cell surface, Single cell rna seq, Tumor, Tumor protein, Tumor recurrence

JTD Keywords: anti-fxiia antibody, artificial surfaces, blood compatibility, complement activation, factor xii, fibrinolytic system, hemocompatible coatings, interactive hemocompatibility, poly(2-methacryloyloxyethyl phosphorylcholine), polyethylene oxide, polymer brushes, radical polymerization, sequential coimmobilization, Antifouling polymer brushes, Protein adsorption

Whenever an artificial surface comes into contact with blood, proteins are rapidly adsorbed onto its surface. This phenomenon, termed fouling, is then followed by a series of undesired reactions involving activation of complement or the coagulation cascade and adhesion of leukocytes and platelets leading to thrombus formation. Thus, considerable efforts are directed towards the preparation of fouling-resistant surfaces with the best possible hemocompatibility. Herein, a comprehensive hemocompatibility study after heparinized blood contact with seven polymer brushes prepared by surface-initiated atom transfer radical polymerization is reported. The resistance to fouling is quantified and thrombus formation and deposition of blood cellular components on the coatings are analyzed. Moreover, identification of the remaining adsorbed proteins is performed via mass spectroscopy to elucidate their influence on the surface hemocompatibility. Compared with an unmodified glass surface, the grafting of polymer brushes minimizes the adhesion of platelets and leukocytes and prevents the thrombus formation. The fouling from undiluted blood plasma is reduced by up to 99%. Most of the identified proteins are connected with the initial events of foreign body reaction towards biomaterial (coagulation cascade proteins, complement component, and inflammatory proteins). In addition, several proteins that are not previously linked with blood-biomaterial interaction are presented and discussed.

JTD Keywords: antifouling surfaces, biosensor, blood-plasma, coagulation, coatings, compatibility, glycoprotein, hemocompatibility, identification, methacrylate), ms identification, polymer brushes, protein adsorption, surface-chemistry, Antifouling surfaces, High-density-lipoprotein, Protein adsorption

Hydroxyapatite nanoparticles are popular tools in bone regeneration, but they have also been used for gene delivery and as anticancer drugs. Understanding their mechanism of action, particularly for the latter application, is crucial to predict their toxicity. To this end, we aimed to elucidate the importance of nanoparticle membrane interactions in the cytotoxicity of MG-63 cells using two different types of nanoparticles. In addition, conventional techniques for studying nanoparticle internalisation were evaluated and compared with newer and less exploited approaches. Hydroxyapatite and magnesium-doped hydroxyapatite nanoparticles were used as suspensions or compacted as specular discs. Comparison between cells seeded on the discs and those supplemented with the nanoparticles allowed direct interaction of the cell membrane with the material to be ruled out as the main mechanism of toxicity. In addition, standard techniques such as flow cytometry were inconclusive when used to assess nanoparticles toxicity. Interestingly, the use of intracellular calcium fluorescent probes revealed the presence of a high number of calcium-rich vesicles after nanoparticle supplementation in cell culture. These structures could not be detected by transmission electron microscopy due to their liquid content. However, by using cryo-soft X-ray imaging, which was used to visualise the cellular ultrastructure without further treatment other than vitrification and to quantify the linear absorption coefficient of each organelle, it was possible to identify them as multivesicular bodies, potentially acting as calcium stores. In the study, an advanced state of degradation of the hydroxyapatite and magnesium-doped hydroxyapatite nanoparticles within MG-63 cells was observed. Overall, we demonstrate that the combination of fluorescent calcium probes together with cryo-SXT is an excellent approach to investigate intracellular calcium, especially when found in its soluble form.Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.

JTD Keywords: adsorption, cryo-soft x-ray tomography, cytotoxicity, expression, flow cytometry, internalisation, intracellular calcium, magnesium, nano, nanomaterials, nanoparticles, proliferation, protein corona, ultrastructure, Calcium-phosphate nanoparticles, Cryo-soft x-ray tomography, Flow cytometry, Hydroxyapatite, Internalisation, Intracellular calcium, Nanoparticles

The methyl erythritol phosphate (MEP) pathway of isoprenoid biosynthesis is essential for malaria parasites and also for several human pathogenic bacteria, thus representing an interesting target for future antimalarials and antibiotics and for diagnostic strategies. We have developed a DNA aptamer (D10) against Plasmodium falciparum 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), the second enzyme of this metabolic route. D10 binds in vitro to recombinant DXR from P. falciparum and Escherichia coli, showing at 10 mu M a ca. 50% inhibition of the bacterial enzyme. In silico docking analysis indicates that D10 associates with DXR in solvent-exposed regions outside the active center pocket. According to fluorescence confocal microscopy data, this aptamer specifically targets in P. falciparum in vitro cultures the apicoplast organelle where the MEP pathway is localized and is, therefore, a highly specific marker of red blood cells parasitized by Plasmodium vs. naive erythrocytes. D10 is also selective for the detection of MEP+ bacteria (e.g., E. coli and Pseudomonas aeruginosa) vs. those lacking DXR (e.g., Enterococcus faecalis). Based on these results, we discuss the potential of DNA aptamers in the development of ligands that can outcompete the performance of the well-established antibody technology for future therapeutic and diagnostic approaches.

JTD Keywords: 1-deoxy-d-xylulose-5-phosphate reductoisomerase, dna aptamers, plasmodium, 1-deoxy-d-xylulose-5-phosphate reductoisomerase, Apicoplast, Dna aptamers, Drug targets, Evolution, Inhibitors, Isoprenoid biosynthesis, Malaria, Methyl erythritol phosphate pathway, Pathway, Plasmodium, Protein-protein, Web server

Background By 2016, signs of emergence of Plasmodium falciparum resistance to artemisinin and partner drugs were detected in the Greater Mekong Subregion. Recently, the independent evolution of artemisinin resistance has also been reported in Africa and South America. This alarming scenario calls for the urgent development of new antimalarials with novel modes of action. We investigated the interference with protein aggregation, which is potentially toxic for the cell and occurs abundantly in all Plasmodium stages, as a hitherto unexplored drug target in the pathogen. Results Attempts to exacerbate the P. falciparum proteome's propensity to aggregation by delivering endogenous aggregative peptides to in vitro cultures of this parasite did not significantly affect their growth. In contrast, protein aggregation inhibitors clearly reduced the pathogen's viability. One such compound, the bis(styrylpyridinium) salt YAT2150, exhibited potent antiplasmodial activity with an in vitro IC50 of 90 nM for chloroquine- and artemisinin-resistant lines, arresting asexual blood parasites at the trophozoite stage, as well as interfering with the development of both sexual and hepatic forms of Plasmodium. At its IC50, this compound is a powerful inhibitor of the aggregation of the model amyloid beta peptide fragment 1-40, and it reduces the amount of aggregated proteins in P. falciparum cultures, suggesting that the underlying antimalarial mechanism consists in a generalized impairment of proteostasis in the pathogen. YAT2150 has an easy, rapid, and inexpensive synthesis, and because it fluoresces when it accumulates in its main localization in the Plasmodium cytosol, it is a theranostic agent. Conclusions Inhibiting protein aggregation in Plasmodium significantly reduces the parasite's viability in vitro. Since YAT2150 belongs to a novel structural class of antiplasmodials with a mode of action that potentially targets multiple gene products, rapid evolution of resistance to this drug is unlikely to occur, making it a promising compound for the post-artemisinin era.

JTD Keywords: amyloid pan-inhibitors, antimalarial drugs, malaria, plasmodium falciparum, protein aggregation, Amyloid formation, Amyloid pan-inhibitors, Antimalarial drugs, Colocalization, Cytosolic delivery, Derivatives, Disease, Drug, In-vitro, Malaria, Mechanism, Plasmodium falciparum, Polyglutamine, Protein aggregation, Yat2150

Cell-material interactions are regulated by mimicking bone extracellular matrix on the surface of biomaterials. In this regard, reproducing the extracellular conditions that promote integrin and growth factor (GF) signaling is a major goal to trigger bone regeneration. Thus, the use of synthetic osteogenic domains derived from bone morphogenetic protein 2 (BMP-2) is gaining increasing attention, as this strategy is devoid of the clinical risks associated with this molecule. In this work, the wrist and knuckle epitopes of BMP-2 are screened to identify peptides with potential osteogenic properties. The most active sequences (the DWIVA motif and its cyclic version) are combined with the cell adhesive RGD peptide (linear and cyclic variants), to produce tailor-made biomimetic peptides presenting the bioactive cues in a chemically and geometrically defined manner. Such multifunctional peptides are next used to functionalize titanium surfaces. Biological characterization with mesenchymal stem cells demonstrates the ability of the biointerfaces to synergistically enhance cell adhesion and osteogenic differentiation. Furthermore, in vivo studies in rat calvarial defects prove the capacity of the biomimetic coatings to improve new bone formation and reduce fibrous tissue thickness. These results highlight the potential of mimicking integrin-GF signaling with synthetic peptides, without the need for exogenous GFs.© 2022 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH.

JTD Keywords: adhesion formation, bmp-2, cell adhesions, in-vivo, integrin, mesenchymal stem-cells, morphogenetic protein-2, multifunctionality, osteoblastic differentiation, osteogenic differentiation, rgd-dwiva, rgd-peptides, titanium biofunctionalization, titanium surfaces, Biomimetic peptides, Cell adhesions, Marrow stromal cells, Multifunctionality, Osteogenic differentiation, Rgd-dwiva, Titanium biofunctionalization

Great advances in cancer treatment have been undertaken in the last years as a consequence of the development of new antitumoral drugs able to target cancer cells with decreasing side effects and a better understanding of the behavior of neoplastic cells during invasion and metastasis. Specifically, drug delivery systems (DDS) based on the use of hydroxyapatite nanoparticles (HAp NPs) are gaining attention and merit a comprehensive review focused on their potential applications. These are derived from the intrinsic properties of HAp (e.g., biocompatibility and biodegradability), together with the easy functionalization and easy control of porosity, crystallinity and morphology of HAp NPs. The capacity to tailor the properties of DLS based on HAp NPs has well-recognized advantages for the control of both drug loading and release. Furthermore, the functionalization of NPs allows a targeted uptake in tumoral cells while their rapid elimination by the reticuloendothelial system (RES) can be avoided. Advances in HAp NPs involve not only their use as drug nanocarriers but also their employment as nanosystems for magnetic hyperthermia therapy, gene delivery systems, adjuvants for cancer immunotherapy and nanoparticles for cell imaging.

JTD Keywords: antitumoral, cancer, cell imaging, controlled-release, drug-carrier, efficient drug-delivery, fatty-acid-metabolism, fe3o4 nanoparticles, gene delivery, hydroxyapatite, hyperthermia, immunotherapy, in-vitro, magnetic hydroxyapatite, nano-hydroxyapatite, protein adsorption, tumor-growth, Calcium-phosphate nanoparticles, Cancer, Immunotherapy

Tauopathies are a group of neurodegenerative diseases characterized by the hyperphosphorylation and deposition of tau proteins in the brain. In Alzheimer's disease, and other related tauopathies, the pattern of tau deposition follows a stereotypical progression between anatomically connected brain regions. Increasing evidence suggests that tau behaves in a "prion-like" manner, and that seeding and spreading of pathological tau drive progressive neurodegeneration. Although several advances have been made in recent years, the exact cellular and molecular mechanisms involved remain largely unknown. Since there are no effective therapies for any tauopathy, there is a growing need for reliable experimental models that would provide us with better knowledge and understanding of their etiology and identify novel molecular targets. In this review, we will summarize the development of cellular models for modeling tau pathology. We will discuss their different applications and contributions to our current understanding of the "prion-like" nature of pathological tau.

JTD Keywords: neurodegeneration, seeding, spreading, Culture model, Efficient generation, Extracellular tau, Familial alzheimers-disease, Microtubule-associated protein, Mouse model, Neurodegeneration, Neurofibrillary tangles, Paired helical filaments, Pathogenic tau, Pluripotent stem-cells, Seeding, Spreading, Tauopathies

ppGpp is an intracellular sensor that, in response to different types of stress, coordinates the rearrangement of the gene expression pattern of bacteria to promote adaptation and survival to new environmental conditions. First described to modulate metabolic adaptive responses, ppGpp modulates the expression of genes belonging to very diverse functional categories. In Escherichia coli, ppGpp regulates the expression of cellular factors that are important during urinary tract infections. Here, we characterize the role of this alarmone in the regulation of the hlyCABD(II) operon of the UPEC isolate J96, encoding the toxin alpha-hemolysin that induces cytotoxicity during infection of bladder epithelial cells. ppGpp is required for the expression of the alpha-hemolysin encoded in hlyCABD(II) by stimulating its transcriptional expression. Prototrophy suppressor mutations in a ppGpp-deficient strain restore the alpha-hemolysin expression from this operon to wild-type levels, confirming the requirement of ppGpp for its expression. ppGpp stimulates hlyCABD(II) expression independently of RpoS, RfaH, Zur, and H-NS. The expression of hlyCABD(II) is promoted at 37 degrees C and at low osmolarity. ppGpp is required for the thermoregulation but not for the osmoregulation of the hlyCABD(II) operon. Studies in both commensal and UPEC isolates demonstrate that no UPEC specific factor is strictly required for the ppGpp-mediated regulation described. Our data further support the role of ppGpp participating in the coordinated regulation of the expression of bacterial factors required during infection.

JTD Keywords: gene regulation, ppgpp, upec, Alpha-hemolysin, Bacterial signal molecule, Determinants, Environmental-regulation, Gene regulation, H-ns, Ppgpp, Protein, Regulator, Rfah, Secretion, Transcription, Upec, Virulence, Α-hemolysin

Cells are constantly exposed to various chemical and physical stimuli. While much has been learned about the biochemical factors that regulate secretory trafficking from the endoplasmic reticulum (ER), much less is known about whether and how this trafficking is subject to regulation by mechanical signals. Here, we show that subjecting cells to mechanical strain both induces the formation of ER exit sites (ERES) and accelerates ER-to-Golgi trafficking. We found that cells with impaired ERES function were less capable of expanding their surface area when placed under mechanical stress and were more prone to develop plasma membrane defects when subjected to stretching. Thus, coupling of ERES function to mechanotransduction appears to confer resistance of cells to mechanical stress. Furthermore, we show that the coupling of mechanotransduction to ERES formation was mediated via a previously unappreciated ER-localized pool of the small GTPase Rac1. Mechanistically, we show that Rac1 interacts with the small GTPase Sar1 to drive budding of COPII carriers and stimulates ER-to-Golgi transport. This interaction therefore represents an unprecedented link between mechanical strain and export from the ER.© 2022 The Authors. Published under the terms of the CC BY 4.0 license.

JTD Keywords: cells, copii, docking, endoplasmic reticulum, endoplasmic-reticulum, er, gtpase, mechanobiology, proliferation, protein, reticulum exit sites, web server, Copii, Fast interaction refinement, Mechanobiology

Erythrina velutina is a Brazilian native tree of the Caatinga (a unique semiarid biome). It is widely used in traditional medicine showing anti-inflammatory and central nervous system modulating activities. The species is a rich source of specialized metabolites, mostly alkaloids and flavonoids. To date, genomic information, biosynthesis, and regulation of flavonoids remain unknown in this woody plant. As part of a larger ongoing research goal to better understand specialized metabolism in plants inhabiting the harsh conditions of the Caatinga, the present study focused on this important class of bioactive phenolics. Leaves and seeds of plants growing in their natural habitat had their metabolic and proteomic profiles analyzed and integrated with transcriptome data. As a result, 96 metabolites (including 43 flavonoids) were annotated. Transcripts of the flavonoid pathway totaled 27, of which EvCHI, EvCHR, EvCHS, EvCYP75A and EvCYP75B1 were identified as putative main targets for modulating the accumulation of these metabolites. The highest correspondence of mRNA vs. protein was observed in the differentially expressed transcripts. In addition, 394 candidate transcripts encoding for transcription factors distributed among the bHLH, ERF, and MYB families were annotated. Based on interaction network analyses, several putative genes of the flavonoid pathway and transcription factors were related, particularly TFs of the MYB family. Expression patterns of transcripts involved in flavonoid biosynthesis and those involved in responses to biotic and abiotic stresses were discussed in detail. Overall, these findings provide a base for the understanding of molecular and metabolic responses in this medicinally important species. Moreover, the identification of key regulatory targets for future studies aiming at bioactive metabolite production will be facilitated.

JTD Keywords: caatinga, erythrina velutina, flavonoids, molecular network, Arabidopsis, Caatinga, Classification, Discovery, Erythrina velutina, Flavonoids, Identification, Mass-spectrometry, Messenger-rna, Metabolism, Molecular network, Natural-products, Protein abundance, Transcriptome

Photosynthesis is a fundamental process that converts photons into chemical energy, driven by large protein complexes at the thylakoid membranes of plants, cyanobacteria, and algae. In plants, water-soluble plastocyanin (Pc) is responsible for shuttling electrons between cytochrome b6f complex and the photosystem I (PSI) complex in the photosynthetic electron transport chain (PETC). For an efficient turnover, a transient complex must form between PSI and Pc in the PETC, which implies a balance between specificity and binding strength. Here, we studied the binding frequency and the unbinding force between suitably oriented plant PSI and Pc under redox control using single molecule force spectroscopy (SMFS). The binding frequency (observation of binding-unbinding events) between PSI and Pc depends on their respective redox states. The interaction between PSI and Pc is independent of the redox state of PSI when Pc is reduced, and it is disfavored in the dark (reduced P700) when Pc is oxidized. The frequency of interaction between PSI and Pc is higher when at least one of the partners is in a redox state ready for electron transfer (ET), and the post-ET situation (PSIRed-PcOx) leads to lower binding. In addition, we show that the binding of ET-ready PcRed to PSI can be regulated externally by Mg2+ ions in solution.

JTD Keywords: architecture, binding-site, complexes, ferredoxin, force spectroscopy, induced structural-changes, interprotein electron transfer, light-dependent interaction, mg2+ concentration, photosystem i, plastocyanin, probe, recognition, reduction, Force spectroscopy, Interprotein electron transfer, Light-dependent interaction, Photosynthetic reaction-center, Photosystem i, Plastocyanin, Single molecule measurements

Alzheimer's disease and Type 2 diabetes are pathological processes associated to ageing. Moreover, there are evidences supporting a mechanistic link between Alzheimer's disease and insulin resistance (one of the first hallmarks of Type 2 diabetes). Regarding Alzheimer's disease, amyloid beta-peptide aggregation into beta-sheets is the main hallmark of Alzheimer's disease. At monomeric state, amyloid beta-peptide is not toxic but its function in brain, if any, is unknown. Here we show, by in silico study, that monomeric amyloid beta-peptide 1-40 shares the tertiary structure with insulin and is thereby able to bind and activate insulin receptor. We validated this prediction experimentally by treating human neuroblastoma cells with increasing concentrations of monomeric amyloid. beta-peptide 1-40. Our results confirm that monomeric amyloid beta-peptide 1-40 activates insulin receptor autophosphorylation, triggering downstream enzyme phosphorylarions and the glucose Transporter 4 translocation to the membrane. On the other hand, neuronal insulin resistance is known to be associated to Alzheimer's disease since early stages. We thus modelled the docking of oligomeric amyloid peptide 1-40 to insulin receptor. We found that oligomeric amyloid. beta-peptide 1-40 blocks insulin receptor, impairing its activation. It was confirmed in vitro by observing the lack of insulin receptor autophosphorylation, and also the impairment of insulin-induced intracellular enzyme activations and the glucose Transporter 4 translocation to the membrane. By biological system analysis, we have carried out a mathematical model recapitulating the process that turns amyloid beta-peptide binding to insulin receptor from the physiological to the pathophysiological regime. Our results suggest that monomeric amyloid beta-peptide 1-40 contributes to mimic insulin effects in the brain, which could be good when neurons have an extra requirement of energy beside the well-known protective effects on insulin intracellular signalling, while its accumulation and subsequent oligomerization blocks the insulin receptor producing insulin resistance and compromising neuronal metabolism and protective pathways.

JTD Keywords: akt, alzheimer’s disease, amyloid β-peptide, insulin, A-beta, Aggregation, Akt, Alzheimer's disease, Alzheimers-disease, Amyloid beta-peptide, Brain, Design, Insulin, Insulin resistance, Precursor protein, Protein-protein docking, Receptor, Resistance, Site

Nanoparticles represent a promising class of material for nanomedicine and molecular biosensing. The formation of a protein corona due to nonspecific particle-protein interactions is a determining factor for the biological fate of nanoparticles in vivo and strongly impacts the performance of nanoparticles when used as biosensors. Nonspecific interactions are usually highly heterogeneous, yet little is known about the heterogeneity of the protein corona that may lead to inter- and intraparticle differences in composition and protein distribution. Here, we present a super-resolution microscopic approach to study the protein corona on single silica nanoparticles and subsequent cellular interactions using multicolor stimulated emission depletion (STED) microscopy. We demonstrate that STED resolves structural features of protein corona on single particles including the distribution on the particle surface and the degree of protein internalization in porous particles. Using multicolor measurements of multiple labeled protein species, we determine the composition of the protein corona at the single-particle level. We quantify particle-to-particle differences in the composition and find that the composition is considerably influenced by the particle geometry. In a subsequent cellular uptake measurement, we demonstrate multicolor STED of protein corona on single particles internalized by cells. Our study shows that STED microscopy opens the window toward mechanistic understanding of protein coronas and aids in the rational design of nanoparticles as nanomedicines and biosensors.

JTD Keywords: insights, multicolor microscopy, nanoparticles, protein corona, quantification, size, sted microscopy, Fluorescence, Quantification, Sted microscopy

In situ tissue engineering strategies are a promising approach to activate the endogenous regenerative potential of the cardiac tissue helping the heart to heal itself after an injury. However, the current use of complex reprogramming vectors for the activation of reparative pathways challenges the easy translation of these therapies into the clinic. Here, we evaluated the response of mouse neonatal and human induced pluripotent stem cell-derived cardiomyocytes to the presence of exogenous lactate, thus mimicking the metabolic environment of the fetal heart. An increase in cardiomyocyte cell cycle activity was observed in the presence of lactate, as determined through Ki67 and Aurora-B kinase. Gene expression and RNA-sequencing data revealed that cardiomyocytes incubated with lactate showed upregulation of BMP10, LIN28 or TCIM in tandem with downregulation of GRIK1 or DGKK among others. Lactate also demonstrated a capability to modulate the production of inflammatory cytokines on cardiac fibroblasts, reducing the production of Fas, Fraktalkine or IL-12p40, while stimulating IL-13 and SDF1a. In addition, the generation of a lactate-rich environment improved ex vivo neonatal heart culture, by affecting the contractile activity and sarcomeric structures and inhibiting epicardial cell spreading. Our results also suggested a common link between the effect of lactate and the activation of hypoxia signaling pathways. These findings support a novel use of lactate in cardiac tissue engineering, modulating the metabolic environment of the heart and thus paving the way to the development of lactate-releasing platforms for in situ cardiac regeneration.Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.

JTD Keywords: cardiac regeneration, cardiac tissue engineering, cell cycle, failure, growth, heart regeneration, induced pluripotent stem cells, ischemia, lactate, metabolic environment, metabolism, mouse, proliferation, repair, Bone morphogenetic protein-10, Cardiac tissue engineering, Cardiomyocytes, Cell cycle, Induced pluripotent stem cells, Lactate, Metabolic environment

Gene duplications occur in prokaryotic genomes at a detectable frequency. In many instances, the biological function of the duplicates is unknown, and hence, the significance of the presence of multiple copies of these genes remains unclear.; Gene duplications significantly impact the gene repertoires of both eukaryotic and prokaryotic microorganisms. The genomes of pathogenic Escherichia coli strains share a group of duplicated genes whose function is mostly unknown. The irmA gene is one of the duplicates encoded in several pathogenic E. coli strains. The function of its gene product was investigated in the uropathogenic E. coli strain CFT073, which contains a single functional copy. The IrmA protein structure mimics that of human interleukin receptors and likely plays a role during infection. The enteroaggregative E. coli strain 042 contains two functional copies of the irmA gene. In the present work, we investigated their biological roles. The irmA_4509 allele is expressed under several growth conditions. Its expression is modulated by the global regulators OxyR and Hha, with optimal expression at 37 degrees C and under nutritional stress conditions. Expression of the irmA_2244 allele can only be detected when the irmA_4509 allele is knocked out. Differences in the promoter regions of both alleles account for their differential expression. Our results show that under several environmental conditions, the expression of the IrmA protein in strain 042 is dictated by the irmA_4509 allele. The irmA_2244 allele appears to play a backup role to ensure IrmA expression when the irmA_4509 allele loses its function. IMPORTANCE Gene duplications occur in prokaryotic genomes at a detectable frequency. In many instances, the biological function of the duplicates is unknown, and hence, the significance of the presence of multiple copies of these genes remains unclear. In pathogenic E. coli isolates, the irmA gene can be present either as a single copy or in two or more copies. We focused our work on studying why a different pathogenic E. coli strain encodes two functional copies of the irmA gene. We show that under several environmental conditions, one of the alleles dictates IrmA expression, and the second remains silent. The latter allele is only expressed when the former is silenced. The presence of more than one functional copy of the irmA gene in some pathogenic E. coli strains can result in sufficient expression of this virulence factor during the infection process.

JTD Keywords: 042, aec69, enteroaggregative e. coli, gene duplications, 042, Adaptation, Aec69, Aggregative adherence, Chromosomal genes, Coli, Duplication, Enteroaggregative e, Escherichia-coli, Evolution, Gene duplications, Hha/ymoa, Irma, Mechanism, Outer-membrane, Protein

Yeast genetics made it possible to derive the first fundamental insights into prion composition, conformation, and propagation. Fast-forward 30 years and the same model organism is now proving an extremely powerful tool to comprehensively explore the impact of mutations in prion sequences on their function, toxicity, and physical properties. Here, we provide an overview of novel multiplexed strategies where deep mutagenesis is combined to a range of tailored selection assays in yeast, which are particularly amenable for investigating prions and prion-like sequences. By mimicking evolution in a flask, these multiplexed approaches are revealing mechanistic insights on the consequences of prion self-assembly, while also reporting on the structure prion sequences adopt in vivo.Copyright © 2022 Elsevier Ltd. All rights reserved.

JTD Keywords: aggregation, appearance, domains, inheritance, mutations, nucleation, physical basis, propagation, protein, Phase-separation

According to circular economy, wine-making by-products represent a fascinating biomass, which can be used for the sustainable exploitation of polyphenols and the development of new nanotechnological health-promoting products. In this study, polyphenols contained in the grape pomace were extracted by maceration with ethanol in an easy and low dissipative way. The obtained extract, rich in malvidin-3-glucoside, quercetin, pro-cyanidin B2 and gallic acid, was incorporated into phospholipid vesicles tailored for intestinal delivery. To improve their performances, vesicles were enriched with gelatine or a maltodextrin (Nutriose (R)), or their com-bination (gelatine-liposomes, nutriosomes and gelatine-nutriosomes). The small (-147 nm) and negatively charged (--50mV) vesicles were stable at different pH values mimicking saliva (6.75), gastric (1.20) and intestinal (7.00) environments. Vesicles effectively protected intestinal cells (Caco-2) from the oxidative stress and promoted the biofilm formation by probiotic bacteria. A preliminary evaluation of the vesicle feasibility at industrial levels was also performed, analysing the economic and energetic costs needed for their production.

JTD Keywords: Adhesion, Antioxidant activity, Caco-2 cells, Dextrin, Grape pomace extract, Lactobacillus-reuteri, Manufacturing costs, Oxidative stress, Ph, Phospholipid vesicles, Polyphenols, Probiotic bacteria, Protein

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is an important regulator of extracellular matrix turnover that has been traditionally regarded as a potential tumor suppressor owing to its inhibitory effects of matrix metal-loproteinases. Intriguingly, this interpretation has been challenged by the consistent observation that increased expression of TIMP-1 is associated with poor prognosis in virtually all cancer types including lung cancer, supporting a tumor-promoting function. However, how TIMP-1 is dysregulated within the tumor micro-environment and how it drives tumor progression in lung cancer is poorly understood. We analyzed the expression of TIMP-1 and its cell surface receptor CD63 in two major lung cancer subtypes: lung adenocarci-noma (ADC) and squamous cell carcinoma (SCC), and defined the tumor-promoting effects of their interac-tion. We found that TIMP-1 is aberrantly overexpressed in tumor-associated fibroblasts (TAFs) in ADC compared to SCC. Mechanistically, TIMP-1 overexpression was mediated by the selective hyperactivity of the pro-fibrotic TGF-61/SMAD3 pathway in ADC-TAFs. Likewise, CD63 was upregulated in ADC compared to SCC cells. Genetic analyses revealed that TIMP-1 secreted by TGF-61-activated ADC-TAFs is both nec-essary and sufficient to enhance growth and invasion of ADC cancer cells in culture, and that tumor cell expression of CD63 was required for these effects. Consistently, in vivo analyses revealed that ADC cells co-injected with fibroblasts with reduced SMAD3 or TIMP-1 expression into immunocompromised mice attenu-ated tumor aggressiveness compared to tumors bearing parental fibroblasts. We also found that high TIMP1 and CD63 mRNA levels combined define a stronger prognostic biomarker than TIMP1 alone. Our results identify an excessive stromal TIMP-1 within the tumor microenvironment selectively in lung ADC, and implicate it in a novel tumor-promoting TAF-carcinoma crosstalk, thereby pointing to TIMP-1/CD63 interaction as a novel therapeutic target in lung cancer. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

JTD Keywords: cancer-associated fibroblast, cd63, fibrosis, smad3, tgf-β1, timp-1, Angiogenesis, Cancer cells, Cancer-associated fibroblast, Cd63, Expression, Fibrosis, Hepatocellular-carcinoma, Metalloproteinases, Nintedanib, Prognostic-significance, Protein, Smad3, Squamous-cell carcinoma, Tgf-? 1, Tgf-β1, Timp-1, Tissue inhibitor, Tumor microenvironment

The histone demethylase KDM1A is a multi- faceted regulator of vital developmental processes, including mesodermal and cardiac tube formation during gastrulation. However, it is unknown whether the fine-tuning of KDM1A splicing isoforms, already shown to regulate neuronal maturation, is crucial for the specification and maintenance of cell identity during cardiogenesis. Here, we discovered a temporal modulation of ubKDM1A and KDM1A+2a during human and mice fetal cardiac development and evaluated their impact on the regulation of cardiac differentiation. We revealed a severely impaired cardiac differentiation in KDM1A(-/-) hESCs that can be rescued by re-expressing ubKDM1A or catalytically impaired ubKDM1A-K661A, but not by KDM1A+2a or KDM1A+2a-K661A. Conversely, KDM1A+2a(-/-) hESCs give rise to functional cardiac cells, displaying increased beating amplitude and frequency and enhanced expression of critical cardiogenic markers. Our findings prove the existence of a divergent scaffolding role of KDM1A splice variants, independent of their enzymatic activity, during hESC differentiation into cardiac cells.

JTD Keywords: cell biology, molecular mechanism of gene regulation, omics, Bhlh transcription factor, Corest, Differentiation, Dna, Embryonic stem-cells, Heart, Lsd1, Phosphorylation, Proteins, Stem cells research, Swirm domain

Supramolecular chemistry is the quintessential backbone of all biological processes. It encompasses a wide range from the metabolic network to the self-assembled cytoskeletal network. Combining the chemical diversity with the plethora of functional depth that biological systems possess is a daunting task for synthetic chemists to emulate. The only route for approaching such a challenge lies in understanding the complex and dynamic systems through advanced analytical techniques. The supramolecular complexity that can be successfully generated and analyzed is directly dependent on the analytical treatment of the system parameters. In this review, we illustrate advanced analytical techniques that have been used to investigate various supramolecular systems including complex mixtures, dynamic self-assembly, and functional nanomaterials. The underlying theme of such an overview is not only the exceeding detail with which traditional experiments can be probed but also the fact that complex experiments can now be attempted owing to the analytical techniques that can resolve an ensemble in astounding detail. Furthermore, the review critically analyzes the current state of the art analytical techniques and suggests the direction of future development. Finally, we envision that integrating multiple analytical methods into a common platform will open completely new possibilities for developing functional chemical systems.

JTD Keywords: analytical techniques, dynamic self-assembly, high-speed afm, liquid cell tem, Analytical technique, Analytical techniques, Biological process, Chemical analysis, Chemical diversity, Complex networks, Cytoskeletal network, Dynamic self-assembly, High-speed afm, Hydrogels, In-situ, Liquid cell tem, Metabolic network, Microscopy, Nanoscale, Proteins, Self assembly, Supramolecular chemistry, Supramolecular systems, System chemistry, Systems chemistry

The integration of active cell machinery with synthetic building blocks is the bridge toward developing synthetic cells with biological functions and beyond. Self-replication is one of the most important tasks of living systems, and various complex machineries exist to execute it. In Escherichia coli, a contractile division ring is positioned to mid-cell by concentration oscillations of self-organizing proteins (MinCDE), where it severs membrane and cell wall. So far, the reconstitution of any cell division machinery has exclusively been tied to liposomes. Here, the reconstitution of a rudimentary bacterial divisome in fully synthetic bicomponent dendrimersomes is shown. By tuning the membrane composition, the interaction of biological machinery with synthetic membranes can be tailored to reproduce its dynamic behavior. This constitutes an important breakthrough in the assembly of synthetic cells with biological elements, as tuning of membrane-divisome interactions is the key to engineering emergent biological behavior from the bottom-up.

JTD Keywords: bacterial cell division, bottom-up synthetic biology, dendrimersomes, dynamic min patterns, ftsz assembly, Bacterial cell division, Bottom-up synthetic biology, Dendrimersomes, Dynamic min patterns, Dynamics, Ftsz assembly, Ftsz filaments, Mind, Organization, Pole oscillation, Polymersome membranes, Proteins, Rapid pole, Synthetic cells, Vesicles

Moderate exercise has well-founded benefits in cardiovascular health. However, increasing, yet controversial, evidence suggests that extremely trained athletes may not be protected from cardiovascular events as much as moderately trained individuals. In our rodent model, intensive but not moderate training promoted aorta and carotid stiffening and elastic lamina ruptures, tunica media thickening of intramyocardial arteries, and an imbalance between vasoconstrictor and relaxation agents. An up-regulation of angiotensin-converter enzyme, miR-212, miR-132, and miR-146b might account for this deleterious remodeling. Most changes remained after a 4-week detraining. In conclusion, our results suggest that intensive training blunts the benefits of moderate exercise. (C) 2022 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.

JTD Keywords: atherosclerosis, cacs, coronary artery calcium score, cad, coronary artery disease, coronary artery disease, cv, cardiovascular, endurance exercise, extreme sport, mmp9, matrix metalloproteinase 9, no, nitric oxide, phe, phenylephrine, vsmc, vascular smooth muscle cell, Age, Atherosclerosis, Cacs, coronary artery calcium score, Cad, coronary artery disease, Coronary artery disease, Coronary atherosclerosis, Cv, cardiovascular, Disease, Endurance exercise, Extreme sport, Metalloproteinases, Micrornas, Mmp9, matrix metalloproteinase 9, No, nitric oxide, Phe, phenylephrine, Physical-activity, Prevalence, Rats, Relevance, Risk, Vascular stiffening, Vsmc, vascular smooth muscle cell

Biomolecular gradients are widely present in multiple biological processes. Historically they were reproduced in vitro by using micropipettes, Boyden and Zigmond chambers, or hydrogels. Despite the great utility of these setups in the study of gradient-related problems such as chemotaxis, they face limitations when trying to translate more complex in vivo-like scenarios to in vitro systems. In the last 20 years, the advances in manufacturing of micromechanical systems (MEMS) had opened the possibility of applying this technology to biology (BioMEMS). In particular, microfluidics has proven extremely efficient in setting-up biomolecular gradients which are stable, controllable, reproducible and at length scales that are relevant to cells. In this chapter, we give an overview of different methods to generate molecular gradients using microfluidics, then we discuss the different steps of the pipeline to fabricate a gradient generator microfluidic device, and at the end, we show an application example of the fabrication of a microfluidic device that can be used to generate a surface-bound biomolecular gradient.© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.

JTD Keywords: biomems, gradient, microfluidics, model, nanotechnology, proteins, Biomems, Gradient, Mechanisms, Microfabrication, Microfluidics, Nanotechnology

It is not well understood why diabetic individuals are more prone to develop severe COVID-19. To this, we here established a human kidney organoid model promoting early hallmarks of diabetic kidney disease development. Upon SARS-CoV-2 infection, diabetic-like kidney organoids exhibited higher viral loads compared with their control counterparts. Genetic deletion of the angiotensin-converting enzyme 2 (ACE2) in kidney organoids under control or diabetic-like conditions prevented viral detection. Moreover, cells isolated from kidney biopsies from diabetic patients exhibited altered mitochondrial respiration and enhanced glycolysis, resulting in higher SARS-CoV-2 infections compared with non-diabetic cells. Conversely, the exposure of patient cells to dichloroacetate (DCA), an inhibitor of aerobic glycolysis, resulted in reduced SARS-CoV-2 infections. Our results provide insights into the identification of diabetic-induced metabolic programming in the kidney as a critical event increasing SARS-CoV-2 infection susceptibility, opening the door to the identification of new interventions in COVID-19 pathogenesis targeting energy metabolism.Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.

JTD Keywords: complications, coronavirus, cultured-cells, disease, distal tubule, mouse, protein, reveals, spike, Ace2, Angiotensin-converting enzyme 2, Angiotensin-converting enzyme-2, Covid-19, Diabetes 2, Human kidney organoids, Sars-cov-2

Heterotopic ossification (HO) is a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues. Despite being a frequent complication of orthopedic and trauma surgery, brain and spinal injury, the etiology of HO is poorly understood. The aim of this study is to evaluate the hypothesis that a sustained local ionic homeostatic imbalance (SLIHI) created by mineral formation during tissue calcification modulates inflammation to trigger HO. This evaluation also considers the role SLIHI could play for the design of cell-free, drug-free osteoinductive bone graft substitutes. The evaluation contains five main sections. The first section defines relevant concepts in the context of HO and provides a summary of proposed causes of HO. The second section starts with a detailed analysis of the occurrence and involvement of calcification in HO. It is followed by an explanation of the causes of calcification and its consequences. This allows to speculate on the potential chemical modulators of inflammation and triggers of HO. The end of this second section is devoted to in vitro mineralization tests used to predict the ectopic potential of materials. The third section reviews the biological cascade of events occurring during pathological and material-induced HO, and attempts to propose a quantitative timeline of HO formation. The fourth section looks at potential ways to control HO formation, either acting on SLIHI or on inflammation. Chemical, physical, and drug-based approaches are considered. Finally, the evaluation finishes with a critical assessment of the definition of osteoinduction.

JTD Keywords: apatite, beta-tricalcium phosphate, bone, bone graft, bone morphogenetic protein, demineralized bone-matrix, experimental myositis-ossificans, extracellular calcium, heterotopic ossification, in-vitro, inflammation, multinucleated giant-cells, osteoinduction, spinal-cord-injury, total hip-arthroplasty, traumatic brain-injury, Apatite, Calcium-sensing receptor, Osteoinduction

Cell nuclei are submitted to mechanical forces, which in turn affect nuclear and cell functions. Recent evidence shows that a crucial mechanically regulated nuclear function is nucleocytoplasmic transport, mediated by nuclear pore complexes (NPCs). Mechanical regulation occurs at two levels: first, by force application to the nucleus, which increases NPC permeability likely through NPC stretch. Second, by the mechanical properties of the transported proteins themselves, as mechanically labile proteins translocate through NPCs faster than mechanically stiff ones. In this perspective, we discuss this evidence and the associated mechanisms by which mechanics can regulate the nucleo-cytoplasmic partitioning of proteins. Finally, we analyze how mechanical regulation of nucleocytoplasmic transport can provide a systematic approach to the study of mechanobiology and open new avenues both in fundamental and applied research. (C) 2022 Author(s).

JTD Keywords: Architecture, Association, Force, Nuclear-pore complex, Pathways, Protein import, Sun1

Mechanical force controls fundamental cellular processes in health and disease, and increasing evidence shows that the nucleus both experiences and senses applied forces. Such forces can lead to the nuclear translocation of proteins, but whether force controls nucleocytoplasmic transport, and how, remains unknown. Here we show that nuclear forces differentially control passive and facilitated nucleocytoplasmic transport, setting the rules for the mechanosensitivity of shuttling proteins. We demonstrate that nuclear force increases permeability across nuclear pore complexes, with a dependence on molecular weight that is stronger for passive than for facilitated diffusion. Owing to this differential effect, force leads to the translocation of cargoes into or out of the nucleus within a given range of molecular weight and affinity for nuclear transport receptors. Further, we show that the mechanosensitivity of several transcriptional regulators can be both explained by this mechanism and engineered exogenously by introducing appropriate nuclear localization signals. Our work unveils a mechanism of mechanically induced signalling, probably operating in parallel with others, with potential applicability across signalling pathways.; Andreu et al. show that force regulates nucleocytoplasmic transport by weakening the permeability barrier of nuclear pore complexes, affecting passive and facilitated diffusion in different ways.

JTD Keywords: Activation, Inhibitor, Matrix, Mechanotransduction, Nesprins, Nucleoporins, Permeability barrier, Pore complex, Proteins, Transmission

Over the most recent decades, the development of new biological platforms to study disease progression and drug efficacy has been of great interest due to the high increase in the rate of neurodegenerative diseases (NDDs). Therefore, blood-brain barrier (BBB) as an organ-on-a-chip (OoC) platform to mimic brain-barrier performance could offer a deeper understanding of NDDs as well as a very valuable tool for drug permeability testing for new treatments. A very attractive improvement of BBB-oC technology is the integration of detection systems to provide continuous monitoring of biomarkers in real time and a fully automated analysis of drug permeably, rendering more efficient platforms for commercialization. In this Perspective, an overview of the main BBB-oC configurations is introduced and a critical vision of the BBB-oC platforms integrating electronic read out systems is detailed, indicating the strengths and weaknesses of current devices, proposing the great potential for biosensors integration in BBB-oC. In this direction, we name potential biomarkers to monitor the evolution of NDDs related to the BBB and/or drug cytotoxicity using biosensor technology in BBB-oC.

JTD Keywords: biosensors, blood−brain barrier (bbb), neurodegenerative diseases (ndds), organ-on-a-chip (ooc), Bbb, Biosensors, Blood-brain barrier (bbb), Electrical-resistance, Electrochemical biosensors, Endothelial-cells, In-vitro model, Matrix metalloproteinases, Mechanisms, Neurodegenerative diseases (ndds), Organ-on-a-chip (ooc), Permeability, Stress, Transendothelial electrical resistance (teer), Transepithelial, Transepithelial/transendothelial electrical resistance (teer), Transport

The influence of the properties of different solid substrates on the tethering of two antibodies, IgG1-CR3022 and IgG1-S309, which were specifically engineered for the detection of SARS-CoV-2, has been examined at the molecular level using conventional and accelerated Molecular Dynamics (cMD and aMD, respectively). Two surfaces with very different properties and widely used in immunosensors for diagnosis, amorphous silica and the most stable facet of the face-centered cubic gold structure, have been considered. The effects of such surfaces on the structure and orientation of the immobilized antibodies have been determined by quantifying the tilt and hinge angles that describe the orientation and shape of the antibody, respectively, and the dihedrals that measure the relative position of the antibody arms with respect to the surface. Results show that the interactions with amorphous silica, which are mainly electrostatic due to the charged nature of the surface, help to preserve the orientation and structure of the antibodies, especially of the IgG1-CR3022, indicating that the primary sequence of those antibodies also plays some role. Instead, short-range van der Waals interactions with the inert gold surface cause a higher degree tilting and fraying of the antibodies with respect to amorphous silica. The interactions between the antibodies and the surface also affect the correlation among the different angles and dihedrals, which increases with their strength. Overall, results explain why amorphous silica substrates are frequently used to immobilize antibodies in immunosensors. © 2022 The Authors

JTD Keywords: amorphous silica, antibody immobilization, enzyme, gol d, gold, immobilization, immunosensor, molecu l a r dynamics, molecular dynamics, protein adsorption, sars-cov-2 immunosensor, simulations, spike protein, surface interactions, target, vaccine, Amorphous silica, Antibodies, Antibody engineering, Antibody immobilization, Antibody structure, Article, Chemical detection, Computer model, Controlled study, Dihedral angle, Gold, In-silico, Molecular dynamics, Molecular levels, Molecular-dynamics, Nonhuman, Property, Sars, Sars-cov-2 immunosensor, Severe acute respiratory syndrome coronavirus 2, Silica, Silico studies, Silicon dioxide, Solid substrates, Structure analysis, Substrate chemistry, Substrates, Van der waals forces, Virus detection

Alzheimer’s disease (AD) and other tauopathies are common neurodegenerative diseases in older adults; in contrast, abnormal tau deposition in neurons and glial cells occurs only exceptionally in children. Sarkosyl-insoluble fractions from sporadic AD (sAD) containing paired helical filaments (PHFs) were inoculated unilaterally into the thalamus in newborn and three-month-old wild-type C57BL/6 mice, which were killed at different intervals from 24 h to six months after inoculation. Tau-positive cells were scanty and practically disappeared at three months in mice inoculated at the age of a newborn. In contrast, large numbers of tau-positive cells, including neurons and oligodendrocytes, were found in the thalamus of mice inoculated at three months and killed at the ages of six months and nine months. Mice inoculated at the age of newborn and re-inoculated at the age of three months showed similar numbers and distribution of positive cells in the thalamus at six months and nine months. This study shows that (a) differences in tau seeding between newborn and young adults may be related to the ratios between 3Rtau and 4Rtau, and the shift to 4Rtau predominance in adults, together with the immaturity of connections in newborn mice, and (b) intracerebral inoculation of sAD PHFs in newborn mice does not protect from tau seeding following intracerebral inoculation of sAD PHFs in young/adult mice.

JTD Keywords: alzheimer's disease, alzheimer-disease, alzheimer’s disease, expression, mouse tau, neurofibrillary tangles, newborn, pathological tau, propagation, protein-tau, spread, tau seeding and spreading, thalamus, transgenic mice, Paired helical filaments, Tau seeding and spreading, Thalamus

A hallmark of cancer is cell death evasion, underlying suboptimal responses to chemotherapy, targeted agents, and immunotherapies. The approval of the anti apoptotic BCL2 antagonist venetoclax has fi nally validated the potential of targeting apoptotic pathways in patients with cancer. Nevertheless, pharmacologic modulators of cell death have shown markedly varied responses in preclinical and clinical studies. Here, we review emerging concepts in the use of this class of therapies. Building on these observations, we propose that treatment-induced changes in apoptotic dependency, rather than pretreatment dependencies, will need to be recognized and targeted to realize the precise deployment of these new pharmacologic agents. Signifi cance: Targeting antiapoptotic family members has proven effi cacious and tolerable in some cancers, but responses are infrequent, particularly for patients with solid tumors. Biomarkers to aid patient selection have been lacking. Precision functional approaches that overcome adaptive resistance to these compounds could drive durable responses to chemotherapy, targeted therapy, and immunotherapies.

JTD Keywords: Anti-apoptotic mcl-1, Bcl-x-l, Bim expression, Chemotherapy sensitivity, Combination strategies, Family proteins, Multiple-myeloma, Oblimersen sodium, Phase-i, Venetoclax resistance

Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) enhance the delivery of therapeutic enzymes for replacement therapy of lysosomal storage disorders. Previous studies examined NPs encapsulating or coated with enzymes, but these formulations have never been compared. We examined this using hyaluronidase (HAse), deficient in mucopolysaccharidosis IX, and acid sphingomyelinase (ASM), deficient in types A–B Niemann–Pick disease. Initial screening of size, PDI, ζ potential, and loading resulted in the selection of the Lactel II co-polymer vs. Lactel I or Resomer, and Pluronic F68 surfactant vs. PVA or DMAB. Enzyme input and addition of carrier protein were evaluated, rendering NPs having, e.g., 181 nm diameter, 0.15 PDI, −36 mV ζ potential, and 538 HAse molecules encapsulated per NP. Similar NPs were coated with enzyme, which reduced loading (e.g., 292 HAse molecules/NP). NPs were coated with targeting antibodies (> 122 molecules/NP), lyophilized for storage without alterations, and acceptably stable at physiological conditions. NPs were internalized, trafficked to lysosomes, released active enzyme at lysosomal conditions, and targeted both peripheral organs and the brain after i.v. administration in mice. While both formulations enhanced enzyme delivery compared to free enzyme, encapsulating NPs surpassed coated counterparts (18.4- vs. 4.3-fold enhancement in cells and 6.2- vs. 3-fold enhancement in brains), providing guidance for future applications.

JTD Keywords: active enzymes, encapsulation, enhanced delivery, enzyme therapeutics, formulation parameters, icam-1 targeting, icam-1-targeted nanocarriers, in vivo biodistribution, in-vitro, lysosomal delivery, model, oral delivery, plga nanoparticles, poly(lactic-co-glycolic acid) nanoparticles, protein therapeutics, surface loading, Acid sphingomyelinase, Enzyme therapeutics, Surface loading

Many neurodegenerative disorders display protein aggregation as a hallmark, Huntingtin and TDP-43 aggregates being characteristic of Huntington disease and amyotrophic lateral sclerosis, respectively. However, whether these aggregates cause the diseases, are secondary by-products, or even have protective effects, is a matter of debate. Mutations in both human proteins can modulate the structure, number and type of aggregates, as well as their toxicity. To study the role of protein aggregates in cellular fitness, we have expressed in a highly tractable unicellular model different variants of Huntingtin and TDP-43. They each display specific patterns of aggregation and toxicity, even though in both cases proteins have to be very highly expressed to affect cell fitness. The aggregation properties of Huntingtin, but not of TDP-43, are affected by chaperones such as Hsp104 and the Hsp40 couple Mas5, suggesting that the TDP-43, but not Huntingtin, derivatives have intrinsic aggregation propensity. Importantly, expression of the aggregating form of Huntingtin causes a significant extension of fission yeast lifespan, probably as a consequence of kidnapping chaperones required for maintaining stress responses off. Our study demonstrates that in general these prion-like proteins do not cause toxicity under normal conditions, and in fact they can protect cells through indirect mechanisms which up-regulate cellular defense pathways. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: aggregation, antioxidant, degradation, features, fission yeast, gene, huntingtin, neurodegenerative diseases, pap1, polyglutamine toxicity, protein aggregation, proteins, stress, tdp-43, Amyotrophic-lateral-sclerosis, Chaperone, Chemistry, Dna binding protein, Dna-binding proteins, Fission yeast, Genetics, Human, Humans, Huntingtin, Metabolism, Molecular chaperones, Neurodegenerative diseases, Prion, Prions, Protein aggregate, Protein aggregates, Protein aggregation, Schizosaccharomyces, Tdp-43

Visual impairments are a critical medical hurdle to be addressed in modern society. Müller glia (MG) have regenerative potential in the retina in lower vertebrates, but not in mammals. However, in mice, in vivo cell fusion between MG and adult stem cells forms hybrids that can partially regenerate ablated neurons.We used organotypic cultures of human retina and preparations of dissociated cells to test the hypothesis that cell fusion between human MG and adult stem cells can induce neuronal regeneration in human systems. Moreover, we established a microinjection system for transplanting human retinal organoids to demonstrate hybrid differentiation.We first found that cell fusion occurs between MG and adult stem cells, in organotypic cultures of human retina as well as in cell cultures. Next, we showed that the resulting hybrids can differentiate and acquire a proto-neural electrophysiology profile when the Wnt/beta-catenin pathway is activated in the adult stem cells prior fusion. Finally, we demonstrated the engraftment and differentiation of these hybrids into human retinal organoids.We show fusion between human MG and adult stem cells, and demonstrate that the resulting hybrid cells can differentiate towards neural fate in human model systems. Our results suggest that cell fusion-mediated therapy is a potential regenerative approach for treating human retinal dystrophies.This work was supported by La Caixa Health (HR17-00231), Velux Stiftung (976a) and the Ministerio de Ciencia e Innovación, (BFU2017-86760-P) (AEI/FEDER, UE), AGAUR (2017 SGR 689, 2017 SGR 926).Published by Elsevier B.V.

JTD Keywords: cell fusion, expression, fusion, ganglion-cells, in-vitro, mouse, müller glia, neural differentiation, organoids, regeneration, retina regeneration, stem cells, stromal cells, transplantation, 4',6 diamidino 2 phenylindole, 5' nucleotidase, Agarose, Alcohol, Arpe-19 cell line, Article, Beta catenin, Beta tubulin, Bone-marrow-cells, Bromophenol blue, Buffer, Calcium cell level, Calcium phosphate, Calretinin, Canonical wnt signaling, Cd34 antigen, Cell culture, Cell fusion, Cell viability, Coculture, Complementary dna, Confocal microscopy, Cornea transplantation, Cryopreservation, Cryoprotection, Crystal structure, Current clamp technique, Dimethyl sulfoxide, Dodecyl sulfate sodium, Edetic acid, Electrophysiology, Endoglin, Fetal bovine serum, Fibroblast growth factor 2, Flow cytometry, Fluorescence activated cell sorting, Fluorescence intensity, Glyceraldehyde 3 phosphate dehydrogenase, Glycerol, Glycine, Hoe 33342, Immunofluorescence, Immunohistochemistry, Incubation time, Interleukin 1beta, Lentivirus vector, Matrigel, Mercaptoethanol, Microinjection, Mueller cell, Müller glia, N methyl dextro aspartic acid, Nerve cell differentiation, Neural differentiation, Nitrogen, Nonhuman, Organoids, Paraffin, Paraffin embedding, Paraformaldehyde, Patch clamp technique, Penicillin derivative, Phenolsulfonphthalein, Phenotype, Phosphate buffered saline, Phosphoprotein phosphatase inhibitor, Polyacrylamide gel electrophoresis, Potassium chloride, Povidone iodine, Promoter region, Proteinase inhibitor, Real time polymerase chain reaction, Receptor type tyrosine protein phosphatase c, Restriction endonuclease, Retina, Retina dystrophy, Retina regeneration, Retinol, Rhodopsin, Rna extraction, Stem cell, Stem cells, Subcutaneous fat, Tunel assay, Visual impairment, Western blotting

Decellularization procedures have been developed and optimized for the entire organ or tissue blocks, by either perfusion of decellularizing agents through the tissue’s vasculature or submerging large sections in decellularizing solutions. However, some research aims require the analysis of native as well as decellularized tissue slices side by side, but an optimal protocol has not yet been established to address this need. Thus, the main goal of this work was to develop a fast and efficient decellularization method for tissue slices—with an emphasis on lung—while attached to a glass slide. To this end, different decellularizing agents were compared for their effectiveness in cellular removal while preserving the extracellular matrix. The intensity of DNA staining was taken as an indicator of remaining cells and compared to untreated sections. The presence of collagen, elastin and laminin were quantified using immunostaining and signal quantification. Scaffolds resulting from the optimized protocol were mechanically characterized using atomic force microscopy. Lung scaffolds were recellularized with mesenchymal stromal cells to assess their biocompatibility. Some decellularization agents (CHAPS, triton, and ammonia hydroxide) did not achieve sufficient cell removal. Sodium dodecyl sulfate (SDS) was effective in cell removal (1% remaining DNA signal), but its sharp reduction of elastin signal (only 6% remained) plus lower attachment ratio (32%) singled out sodium deoxycholate (SD) as the optimal treatment for this application (6.5% remaining DNA signal), due to its higher elastin retention (34%) and higher attachment ratio (60%). Laminin and collagen were fully preserved in all treatments. The SD decellularization protocol was also successful for porcine and murine (mice and rat) lungs as well as for other tissues such as the heart, kidney, and bladder. No significant mechanical differences were found before and after sample decellularization. The resulting acellular lung scaffolds were shown to be biocompatible (98% cell survival after 72 h of culture). This novel method to decellularize tissue slices opens up new methodological possibilities to better understand the role of the extracellular matrix in the context of several diseases as well as tissue engineering research and can be easily adapted for scarce samples like clinical biopsies. Copyright © 2022 Narciso, Ulldemolins, Júnior, Otero, Navajas, Farré, Gavara and Almendros.

JTD Keywords: biocompatibility, bioscaffold recellularization, decellularization, extracellular matrix, flow, impact, lung, scaffolds, tissue slices, Ammonia, Bio-scaffolds, Biocompatibility, Biological organs, Bioscaffold recellularization, Cell removal, Cells, Collagen, Cytology, Decellularization, Dna, Dna signals, Elastin, Extracellular matrices, Extracellular matrix, Extracellular-matrix, Glycoproteins, Laminin, Lung, Mammals, Recellularization, Scaffolds (biology), Sodium deoxycholate, Sulfur compounds, Tissue, Tissue slice, Tissue slices

Transmission of a plasmid from one bacterial cell to another, in several instances, underlies the dissemination of antimicrobial resistance (AMR) genes. The process requires well-characterized enzymatic machinery that facilitates cell-to-cell contact and the transfer of the plasmid.

JTD Keywords: antimicrobial resistance, bacterial ig-like proteins, bacterial lg-like proteins, chromosomal genes, identification, inca/c, mutational analysis, plasmid conjugation, products, r-factors, resistance plasmids, salmonella-enterica, sequence, Antimicrobial resistance, Bacterial ig-like proteins, Escherichia-coli, Plasmid conjugation

Charge separation and transport through the reaction center of photosystem I (PSI) is an essential part of the photosynthetic electron transport chain. A strategy is developed to immobilize and orient PSI complexes on gold electrodes allowing to probe the complex's electron acceptor side, the chlorophyll special pair P700. Electrochemical scanning tunneling microscopy (ECSTM) imaging and current-distance spectroscopy of single protein complex shows lateral size in agreement with its known dimensions, and a PSI apparent height that depends on the probe potential revealing a gating effect in protein conductance. In current-distance spectroscopy, it is observed that the distance-decay constant of the current between PSI and the ECSTM probe depends on the sample and probe electrode potentials. The longest charge exchange distance (lowest distance-decay constant ?) is observed at sample potential 0 mV/SSC (SSC: reference electrode silver/silver chloride) and probe potential 400 mV/SSC. These potentials correspond to hole injection into an electronic state that is available in the absence of illumination. It is proposed that a pair of tryptophan residues located at the interface between P700 and the solution and known to support the hydrophobic recognition of the PSI redox partner plastocyanin, may have an additional role as hole exchange mediator in charge transport through PSI.© 2021 Wiley-VCH GmbH.

JTD Keywords: azurin, current distance decay spectroscopy, cytochrome c(6), electrochemical scanning tunneling microscopy (ecstm), electrochemistry, photosystem i, photosystem-i, plastocyanin, protein electron transfer, recognition, single metalloprotein, single molecules, structural basis, tunneling spectroscopy, 'current, Amino acids, Charge transfer, Chlorine compounds, Current distance decay spectroscopy, Decay spectroscopies, Distance decay, Electrochemical scanning tunneling microscopy, Electrochemical scanning tunneling microscopy (ecstm), Electrodes, Electron transfer, Electron transport properties, Gold compounds, Photosystem i, Photosystems, Protein electron transfer, Protein electron-transfer, Proteins, Scanning tunneling microscopy, Silver halides, Single molecule, Single molecules

The use of broadly neutralizing antibodies against human immunodeficiency virus type 1 (HIV-1) has been shown to be a promising therapeutic modality in the prevention of HIV infection. Understanding the b12-gp120 binding mechanism under physiological conditions may assist the development of more broadly effective antibodies. In this work, the main conformations and interactions between the receptor-binding domain (RBD) of spike glycoprotein gp120 of HIV-1 and the IgG1-b12 mAb are studied. Accelerated molecular dynamics (aMD) and ab initio hybrid molecular dynamics have been combined to determine the most persistent interactions between the most populated conformations of the antibody-antigen complex under physiological conditions. The results show the most persistent receptor-binding mapping in the conformations of the antibody-antigen interface in solution. The binding-free-energy decomposition reveals a small enhancement in the contribution played by the CDR-H3 region to the b12-gp120 interface compared to the crystal structure.

JTD Keywords: antibody, complex, functionals, gp120 envelope glycoprotein, hiv, immunodeficiency-virus, noncovalent interactions, simulations, software integration, Ab initio, Accelerated molecular dynamics, Accelerated molecular-dynamics, Antibodies, Antigens, Binding energy, Binding mechanisms, Computational studies, Crystal structure, Diseases, Free energy, Hiv infection, Human immunodeficiency virus, Molecular dynamics, Neutralizing antibodies, Physiological condition, Physiology, Receptor-binding domains, Therapeutic modality, Viruses

Influenza recombinant proteins and virus-like particles (VLPs) play an important role in vaccine development (e.g., CadiFluS). However, their production from mammalian cells suffers from low yields and lack of control of the final VLPs. To improve these issues, characterization techniques able to visualize and quantify the different steps of the process are needed. Fluorescence microscopy represents a powerful tool able to image multiple protein targets; however, its limited resolution hinders the study of viral constructs. Here, we propose the use of super-resolution microscopy and in particular of DNA-point accumulation for imaging in nanoscale topography (DNA-PAINT) microscopy as a characterization method for recombinant viral proteins on both cells and VLPs. We were able to quantify the amount of the three main influenza proteins (hemagglutinin (HA), neuraminidase (NA), and ion channel matrix protein 2 (M2)) per cell and per VLP with nanometer resolution and single-molecule sensitivity, proving that DNA-PAINT is a powerful technique to characterize recombinant viral constructs.

JTD Keywords: dna-paint, hemagglutinin, influenza, neuraminidase, paint, recombinant proteins, single-molecule localization microscopy, single-particle analysis, virus-like particles, Dna-paint, Hemagglutinin, Influenza, Neuraminidase, Paint, Recombinant proteins, Single particle analysis, Single-molecule localization microscopy, Single-particle analysis, Super-resolution microscopy, Superresolution microscopy, Virus-like particles

Background Cellular prion protein (PrP(C)) is a cell surface GPI-anchored protein, usually known for its role in the pathogenesis of human and animal prionopathies. However, increasing knowledge about the participation of PrP(C) in prion pathogenesis contrasts with puzzling data regarding its natural physiological role. PrP(C) is expressed in a number of tissues, including at high levels in the nervous system, especially in neurons and glial cells, and while previous studies have established a neuroprotective role, conflicting evidence for a synaptic function has revealed both reduced and enhanced long-term potentiation, and variable observations on memory, learning, and behavior. Such evidence has been confounded by the absence of an appropriate knock-out mouse model to dissect the biological relevance of PrP(C), with some functions recently shown to be misattributed to PrP(C) due to the presence of genetic artifacts in mouse models. Here we elucidate the role of PrP(C) in the hippocampal circuitry and its related functions, such as learning and memory, using a recently available strictly co-isogenic Prnp(0/0) mouse model (Prnp(ZH3/ZH3)). Results We performed behavioral and operant conditioning tests to evaluate memory and learning capabilities, with results showing decreased motility, impaired operant conditioning learning, and anxiety-related behavior in Prnp(ZH3/ZH3) animals. We also carried in vivo electrophysiological recordings on CA3-CA1 synapses in living behaving mice and monitored spontaneous neuronal firing and network formation in primary neuronal cultures of Prnp(ZH3/ZH3) vs wildtype mice. PrP(C) absence enhanced susceptibility to high-intensity stimulations and kainate-induced seizures. However, long-term potentiation (LTP) was not enhanced in the Prnp(ZH3/ZH3) hippocampus. In addition, we observed a delay in neuronal maturation and network formation in Prnp(ZH3/ZH3) cultures. Conclusion Our results demonstrate that PrP(C) promotes neuronal network formation and connectivity. PrP(C) mediates synaptic function and protects the synapse from excitotoxic insults. Its deletion may underlie an epileptogenic-susceptible brain that fails to perform highly cognitive-demanding tasks such as associative learning and anxiety-like behaviors.

JTD Keywords: anxiety, behavior, cellular prion protein, epilepsy, hippocampus, Anxiety, Behavior, Cellular prion protein, Developmental expression, Epilepsy, Gene-expression, Hippocampus, Kainate-induced seizures, Lacking, Ltp, Memory, Messenger-rna, Motor behavior, Mouse, Prp

Despite tremendous progress in the understanding of COVID-19, mechanistic insight into immunological, disease-driving factors remains limited. We generated maVie16, a mouse-adapted SARS-CoV-2, by serial passaging of a human isolate. In silico modeling revealed how only three Spike mutations of maVie16 enhanced interaction with murine ACE2. maVie16 induced profound pathology in BALB/c and C57BL/6 mice, and the resulting mouse COVID-19 (mCOVID-19) replicated critical aspects of human disease, including early lymphopenia, pulmonary immune cell infiltration, pneumonia, and specific adaptive immunity. Inhibition of the proinflammatory cyto-kines IFN? and TNF substantially reduced immunopathology. Importantly, genetic ACE2-deficiency completely prevented mCOVID-19 development. Finally, inhalation therapy with recombinant ACE2 fully protected mice from mCOVID-19, revealing a novel and efficient treatment. Thus, we here present maVie16 as a new tool to model COVID-19 for the discovery of new therapies and show that disease severity is determined by cytokine-driven immunopathology and critically dependent on ACE2 in vivo. © Gawish et al.

JTD Keywords: covid-19 mouse model, covid-19 therapy, cytokine storm, immunology, inflammation, mavie16, mouse, mouse-adapted sars-cov-2, program, recombinant soluble ace2, tmprss2, Adaptive immunity, Angiotensin converting enzyme 2, Angiotensin-converting enzyme 2, Animal, Animal cell, Animal experiment, Animal model, Animal tissue, Animals, Apoptosis, Article, Bagg albino mouse, Breathing rate, Bronchoalveolar lavage fluid, C57bl mouse, Cell composition, Cell infiltration, Controlled study, Coronavirus disease 2019, Coronavirus spike glycoprotein, Covid-19, Cytokeratin 18, Cytokine production, Dipeptidyl carboxypeptidase, Disease model, Disease models, animal, Disease severity, Drosophila-melanogaster, Enzyme linked immunosorbent assay, Expression vector, Flow cytometry, Gamma interferon, Gene editing, Gene expression, Gene mutation, Genetic engineering, Genetics, Glycosylation, High mobility group b1 protein, Histology, Histopathology, Immune response, Immunocompetent cell, Immunology, Immunopathology, Interferon-gamma, Interleukin 2, Metabolism, Mice, inbred balb c, Mice, inbred c57bl, Mouse-adapted sars-cov-2, Myeloperoxidase, Neuropilin 1, Nonhuman, Nucleocapsid protein, Pathogenicity, Peptidyl-dipeptidase a, Pyroptosis, Recombinant soluble ace2, Renin angiotensin aldosterone system, Rna extraction, Rna isolation, Sars-cov-2, Severe acute respiratory syndrome coronavirus 2, Spike glycoprotein, coronavirus, T lymphocyte activation, Trabecular meshwork, Tumor necrosis factor, Virology, Virus load, Virus replication, Virus transmission, Virus virulence

Several studies have demonstrated the different characteristics of tau seeding and spreading following intracerebral inoculation in murine models of tau-enriched fractions of brain homogenates from AD and other tauopathies. The present study is centered on the importance of host tau in tau seeding and the molecular changes associated with the transformation of host tau into abnormal tau. The brains of three adult murine genotypes expressing different forms of tau—WT (murine 4Rtau), hTau (homozygous transgenic mice knock-out for murine tau protein and heterozygous expressing human forms of 3Rtau and 4Rtau proteins), and mtWT (homozygous transgenic mice knock-out for murine tau protein)—were analyzed following unilateral hippocampal inoculation of sarkosyl-insoluble tau fractions from the same AD and control cases. The present study reveals that (a) host tau is mandatory for tau seeding and spreading following tau inoculation from sarkosyl-insoluble fractions obtained from AD brains; (b) tau seeding does not occur following intracerebral inoculation of sarkosyl-insoluble fractions from controls; (c) tau seeding and spreading are characterized by variable genotype-dependent tau phosphorylation and tau nitration, MAP2 phosphorylation, and variable activation of kinases that co-localize with abnormal tau deposits; (d) transformation of host tau into abnormal tau is an active process associated with the activation of specific kinases; (e) tau seeding is accompanied by modifications in tau splicing, resulting in the expression of new 3Rtau and 4Rtau isoforms, thus indicating that inoculated tau seeds have the capacity to model exon 10 splicing of the host mapt or MAPT with a genotype-dependent pattern; (e) selective regional and cellular vulnerabilities, and different molecular compositions of the deposits, are dependent on the host tau of mice injected with identical AD tau inocula.

JTD Keywords: 3rtau and 4rtau, alzheimer's disease, alzheimer’s disease, brains, granulovacuolar degeneration, host tau, htau, intranuclear distribution, messenger-rna, pathological tau, propagation, protein-kinases, seeding and spreading, tauopathies, transmission, 3rtau and 4rtau, Alzheimers-disease, Alzheimer’s disease, Host tau, Htau, Seeding and spreading, Tauopathies

A deficient transport of amyloid-beta across the blood-brain barrier, and its diminished clearance from the brain, contribute to neurodegenerative and vascular pathologies, such as Alzheimer's disease and cerebral amyloid angiopathy, respectively. At the blood-brain barrier, amyloid-beta efflux transport is associated with the low-density lipoprotein receptor-related protein 1. However, the precise mechanisms governing amyloid-beta transport across the blood-brain barrier, in health and disease, remain to be fully understood. Recent evidence indicates that the low-density lipoprotein receptor-related protein 1 transcytosis occurs through a tuhulation-mediated mechanism stabilized by syndapin-2. Here, we show that syndapin-2 is associated with amyloid-beta clearance via low-density lipoprotein receptor-related protein 1 across the blood-brain barrier. We further demonstrate that risk factors for Alzheimer's disease, amyloid-beta expression and ageing, are associated with a decline in the native expression of syndapin-2 within the brain endothelium. Our data reveals that syndapin-2-mediated pathway, and its balance with the endosomal sorting, are important for amyloid-beta clearance proposing a measure to evaluate Alzheimer's disease and ageing, as well as a target for counteracting amyloid-beta build-up. Moreover, we provide evidence for the impact of the avidity of amyloid-beta assemblies in their trafficking across the brain endothelium and in low-density lipoprotein receptor-related protein 1 expression levels, which may affect the overall clearance of amyloid-beta across the blood-brain barrier.

JTD Keywords: alzheimer’s disease, amyloid-β, blood–brain barrier, syndapin-2, Alzheimer's disease, Alzheimers-disease, Amyloid-beta, Apolipoprotein-j, Blood-brain barrier, Clearance, Expression, Membrane invagination, Peptide, Protein, Rab gtpases, Receptor, Syndapin-2, Transport, Tubular transcytosis

Mycobacterium bovis bacillus Calmette-Guérin (BCG) efficacy as an immunotherapy tool can be influenced by the genetic background or immune status of the treated population and by the BCG substrain used. BCG comprises several substrains with genetic differences that elicit diverse phenotypic characteristics. Moreover, modifications of phenotypic characteristics can be influenced by culture conditions. However, several culture media formulations are used worldwide to produce BCG. To elucidate the influence of growth conditions on BCG characteristics, five different substrains were grown on two culture media, and the lipidic profile and physico-chemical properties were evaluated. Our results show that each BCG substrain displays a variety of lipidic profiles on the outermost surface depending on the growth conditions. These modifications lead to a breadth of hydrophobicity patterns and a different ability to reduce neutral red dye within the same BCG substrain, suggesting the influence of BCG growth conditions on the interaction between BCG cells and host cells.

JTD Keywords: cell wall, efficacy, glycerol, hydrophobicity, lipid, neutral red, pdim, pgl, protein, strains, viability, virulence, Acylglycerol, Albumin, Article, Asparagine, Bacterial cell wall, Bacterial gene, Bacterium culture, Bcg vaccine, Catalase, Cell wall, Chloroform, Controlled study, Escherichia coli, Gene expression, Genomic dna, Glycerol, Glycerol monomycolate, Hexadecane, Housekeeping gene, Hydrophobicity, Immune response, Immunogenicity, Immunotherapy, Lipid, Lipid fingerprinting, Magnesium sulfate, Mercaptoethanol, Methanol, Methylglyoxal, Molybdatophosphoric acid, Mycobacterium bovis bcg, Neutral red, Nonhuman, Pdim, Petroleum ether, Pgl, Phenotype, Physical chemistry, Real time reverse transcription polymerase chain reaction, Rna 16s, Rna extraction, Rv0577, Staining, Thin layer chromatography, Unclassified drug

Drug development is an ever-growing field, increasingly requesting reliable in vitro tools to speed up early screening phases, reducing the need for animal experiments. In oral delivery, understanding the absorption pattern of a new drug in the small intestine is paramount. Classical two-dimensional (2D) in vitro models are generally too simplistic and do not accurately represent native tissues. The main goal of this work was to develop an advanced three-dimensional (3D) in vitro intestinal model to test absorption in a more reliable manner, by better mimicking the native environment. The 3D model is composed of a collagen-based stromal layer with embedded fibroblasts mimicking the intestinal lamina propria and providing support for the epithelium, composed of enterocytes and mucus-secreting cells. An endothelial layer, surrogating the absorptive capillary network, is also present. The cellular crosstalk between the different cells present in the model is unveiled, disclosing key players, namely those involved in the contraction of collagen by fibroblasts. The developed 3D model presents lower levels of P-glycoprotein (P-gp) and Multidrug Resistance Protein 2 (MRP2) efflux transporters, which are normally overexpressed in traditional Caco-2 models, and are paramount in the absorption of many compounds. This, allied with transepithelial electrical resistance (TEER) values closer to physiological ranges, leads to improved and more reliable permeability outcomes, which are observed when comparing our results with in vivo data.

JTD Keywords: 3d intestinal model, drug absorption, drug development, endothelium, hydrogel, 3d intestinal model, 3d modeling, 3d models, 3d-modeling, Alkaline-phosphatase, Animal experiments, Biopharmaceutics classification, Caco-2 cells, Cell culture, Collagen, Collagen gel, Drug absorption, Drug development, Endothelium, Fibroblasts, Glycoproteins, Hydrogel, In-vitro, Matrix metalloproteinases, Membrane-permeability, Paracellular transport, Permeability, Single-pass vs., Speed up

Most lectins bind carbohydrate ligands with relatively low affinity, making the identification of optimal ligands challenging. Here we introduce a point accumulation in nanoscale topography (PAINT) super-resolution microscopy method to capture weak glycan-lectin interactions at the single-molecule level in living cells (Glyco-PAINT). Glyco-PAINT exploits weak and reversible sugar binding to directly achieve single-molecule detection and quantification in cells and is used to establish the relative kon and koff rates of a synthesized library of carbohydrate-based probes, as well as the diffusion coefficient of the receptor-sugar complex. Uptake of ligands correlates with their binding affinity and residence time to establish structure-function relations for various synthetic glycans. We reveal how sugar multivalency and presentation geometry can be optimized for binding and internalization. Overall, Glyco-PAINT represents a powerful approach to study weak glycan-lectin interactions on the surface of living cells, one that can be potentially extended to a variety of lectin-sugar interactions.© 2021. The Author(s), under exclusive licence to Springer Nature America, Inc.

JTD Keywords: dc-sign, density, dimerization, endocytosis, lateral mobility, ligand-binding, mannose receptor, proteins, recognition, Animal, Animals, Cell membrane, Cell membrane permeability, Chemistry, Cho cell line, Cho cells, Cricetulus, Cysteine-rich domain, Kinetics, Lectin, Lectins, Ligand, Ligands, Molecular library, Multivariate analysis, Polysaccharide, Polysaccharides, Procedures, Protein binding, Single molecule imaging, Small molecule libraries, Structure activity relation, Structure-activity relationship

Outer membrane extensions from the metal-reducing bacterium Shewanella oneidensis MR-1 show an insulating behavior in dry air environment as measured by scanning dielectric microscopy.

JTD Keywords: constant, dielectric polarization, microbial nanowires, nanoscale, transport, Air environment, Bacteria, Bacterial cells, Bacterial nanowires, Dry air, Metal-reducing bacteria, Outer membrane, Phase-minerals, Proteins, Shewanella oneidensis mr-1, Solid phasis, Solid-phase, Space division multiple access, Tubulars

In many physiological situations, BAR proteins reshape membranes with pre-existing curvature (templates), contributing to essential cellular processes. However, the mechanism and the biological implications of this reshaping process remain unclear. Here we show, both experimentally and through modelling, that BAR proteins reshape low curvature membrane templates through a mechanochemical phase transition. This phenomenon depends on initial template shape and involves the co-existence and progressive transition between distinct local states in terms of molecular organization (protein arrangement and density) and membrane shape (template size and spherical versus cylindrical curvature). Further, we demonstrate in cells that this phenomenon enables a mechanotransduction mode, in which cellular stretch leads to the mechanical formation of membrane templates, which are then reshaped into tubules by BAR proteins. Our results demonstrate the interplay between membrane mechanics and BAR protein molecular organization, integrating curvature sensing and generation in a comprehensive framework with implications for cell mechanical responses.

JTD Keywords: aggregation, amphiphysin, domains, vesicles, Article, Cell, Cell component, Curvature, Detection method, Geomembrane, Mechanotransduction, Membrane, Molecular analysis, Phase transition, Physiology, Protein, Self organization

Tau hyperphosphorylation is the first step of neurofibrillary tangle (NFT) formation. In the present study, samples of the entorhinal cortex (EC) and frontal cortex area 8 (FC) of cases with NFT pathology classified as stages I–II, III–IV, and V–VI without comorbidities, and of middle-aged (MA) individuals with no NFT pathology, were analyzed by conventional label-free and SWATH-MS (sequential window acquisition of all theoretical fragment ion spectra mass spectrometry) to assess the (phospho)proteomes. The total number of identified dysregulated phosphoproteins was 214 in the EC, 65 of which were dysregulated at the first stages (I–II) of NFT pathology; 167 phosphoproteins were dysregulated in the FC, 81 of them at stages I–II of NFT pathology. A large percentage of dysregulated phosphoproteins were identified in the two regions and at different stages of NFT progression. The main group of dysregulated phosphoproteins was made up of components of the membranes, cytoskeleton, synapses, proteins linked to membrane transport and ion channels, and kinases. The present results show abnormal phosphorylation of proteins at the first stages of NFT pathology in the elderly (in individuals clinically considered representative of normal aging) and sporadic Alzheimer's disease (sAD). Dysregulated protein phosphorylation in the FC precedes the formation of NFTs and SPs. The most active period of dysregulated phosphorylation is at stages III–IV when a subpopulation of individuals might be clinically categorized as suffering from mild cognitive impairment which is a preceding determinant stage in the progression to dementia. Altered phosphorylation of selected proteins, carried out by activation of several kinases, may alter membrane and cytoskeletal functions, among them synaptic transmission and membrane/cytoskeleton signaling. Besides their implications in sAD, the present observations suggest a molecular substrate for “benign” cognitive deterioration in “normal” brain aging.

JTD Keywords: (phospho)proteomics, alzheimer's disease, amyloid-beta, association guidelines, brain aging, cytoskeleton, frontal-cortex, kinases, lipid rafts, membranes, national institute, neuropathologic assessment, pathological process, protein phosphorylation, synapse pathology, synapses, tau, tau pathology, (phospho)proteomics, Age-related tauopathy, Alzheimer's disease, Brain aging, Cytoskeleton, Kinases, Membranes, Protein phosphorylation, Synapses, Tau

This paper describes the fabrication of microfluidic devices with a focus on controlling the orientation of photosystem I (PSI) complexes, which directly affects the performance of biophotovoltaic devices by maximizing the efficiency of the extraction of electron/hole pairs from the complexes. The surface chemistry of the electrode on which the complexes assemble plays a critical role in their orientation. We compared the degree of orientation on self-assembled monolayers of phenyl-C61-butyric acid and a custom peptide on nanostructured gold electrodes. Biophotovoltaic devices fabricated with the C61 fulleroid exhibit significantly improved performance and reproducibility compared to those utilizing the peptide, yielding a 1.6-fold increase in efficiency. In addition, the C61-based devices were more stable under continuous illumination. Our findings show that fulleroids, which are well-known acceptor materials in organic photovoltaic devices, facilitate the extraction of electrons from PSI complexes without sacrificing control over the orientation of the complexes, highlighting this combination of traditional organic semiconductors with biomolecules as a viable approach to coopting natural photosynthetic systems for use in solar cells.

JTD Keywords: architecture, arrays, construction, metal, nanotubes, performance, photosynthetic proteins, polymer-fullerene, solar-cells, Photocurrent generation

Membrane fission triggered by the endosomal sorting complex required for transport (ESCRT) is an important process observed in several pathogenic and non-pathogenic cellular events. From a synthetic-biology viewpoint, ESCRT proteins represent an interesting machinery for the construction of cell mimetic sub-compartments produced by fission. Since their discovery, the studies on ESCRT-III-mediated action, have mainly focused on protein dynamics, ignoring the role of lipid organization and membrane phase state. Recently, it has been suggested that membrane buds formed by the action of ESCRT-III are generated from transient microdomains in endosomal membranes. However, the interplay between membrane domain formation and ESCRT remodeling pathways has not been investigated. Here, giant unilamellar vesicles made of ternary lipid mixtures, either homogeneous in phase or exhibiting liquid-ordered/liquid-disordered phase coexistence, were employed as a model membrane system. These vesicles were incubated with purified recombinant ESCRT-III proteins from the parasite Entamoeba histolytica. In homogeneous membranes, we observe that EhVps32 can trigger domain formation while EhVps20 preferentially co-localizes in the liquid disordered phase. The addition of EhVps24 appears to induce the formation of intraluminal vesicles produced from the liquid-ordered phase. In phase separated membranes, the intraluminal vesicles are also generated from the liquid-ordered phase and presumably emerge from the phase boundary region. Our findings reinforce the hypothesis that ESCRT-mediated remodeling depends on the membrane phase state. Furthermore, the obtained results point to a potential synthetic biology approach for establishing eukaryotic mimics of artificial cells with microcompartments of specific membrane composition, which can also differ from that of the mother vesicle.

JTD Keywords: cell-membranes, coexistence, complex, escrt-iii, fission, guvs, lipid domains, lipid rafts, membrane fission, microcompartments, microscopy, phase separation, plasma-membrane, protein microarrays, structural basis, ternary mixtures, Escrt-iii, Giant unilamellar vesicles, Guvs, Lipid domains, Membrane fission, Microcompartments, Phase separation, Ternary mixtures

Pulmonary endarterectomy (PEA) resected material offers a unique opportunity to develop an in vitro endothelial cell model of chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to comprehensively analyze the endothelial function, molecular signature, and mitochondrial profile of CTEPH-derived endothelial cells to better understand the pathophysiological mechanisms of endothelial dysfunction behind CTEPH, and to identify potential novel targets for the prevention and treatment of the disease. Isolated cells from specimens obtained at PEA (CTEPH-EC), were characterized based on morphology, phenotype, and functional analyses (in vitro and in vivo tubule formation, proliferation, apoptosis, and migration). Mitochondrial content, morphology, and dynamics, as well as high-resolution respirometry and oxidative stress, were also studied. CTEPH-EC displayed a hyperproliferative phenotype with an increase expression of adhesion molecules and a decreased apoptosis, eNOS activity, migration capacity and reduced angiogenic capacity in vitro and in vivo compared to healthy endothelial cells. CTEPH-EC presented altered mitochondrial dynamics, increased mitochondrial respiration and an unbalanced production of reactive oxygen species and antioxidants. Our study is the foremost comprehensive investigation of CTEPH-EC. Modulation of redox, mitochondrial homeostasis and adhesion molecule overexpression arise as novel targets and biomarkers in CTEPH.

JTD Keywords: angiogenesis, cd31, dysfunction, expression, pathogenesis, thrombus, C-reactive protein

A plethora of applications using polysaccharides have been developed in recent years due to their availability as well as their frequent nontoxicity and biodegradability. These polymers are usually obtained from renewable sources or are byproducts of industrial processes, thus, their use is collaborative in waste management and shows promise for an enhanced sustainable circular economy. Regarding the development of novel delivery systems for biotherapeutics, the potential of polysaccharides is attractive for the previously mentioned properties and also for the possibility of chemical modification of their structures, their ability to form matrixes of diverse architectures and mechanical properties, as well as for their ability to maintain bioactivity following incorporation of the biomolecules into the matrix. Biotherapeutics, such as proteins, growth factors, gene vectors, enzymes, hormones, DNA/RNA, and antibodies are currently in use as major therapeutics in a wide range of pathologies. In the present review, we summarize recent progress in the development of polysaccharide-based hydrogels of diverse nature, alone or in combination with other polymers or drug delivery systems, which have been implemented in the delivery of biotherapeutics in the pharmaceutical and biomedical fields. © 2021 American Chemical Society.

JTD Keywords: biodegradable dextran hydrogels, biotherapeutics, bone morphogenetic protein-2, carrageenan-based hydrogels, chitosan-based hydrogels, controlled delivery, controlled-release, cross-linked hydrogels, growth-factor delivery, hydrogels, in-vitro characterization, polysaccharides, self-healing hydrogel, stimuli-responsiveness, tissue engineering, Antibodies, Bioactivity, Biodegradability, Biomedical fields, Biomolecules, Biotherapeutics, Chemical modification, Circular economy, Controlled delivery, Controlled drug delivery, Delivery systems, Drug delivery system, Functional polymers, Hyaluronic-acid hydrogels, Hydrogels, Industrial processs, Polysaccharides, Recent progress, Renewable sources, Stimuli-responsiveness, Targeted drug delivery, Tissue engineering, Waste management

Multiple targeted therapies are currently explored for pediatric and young adult B-cell precursor acute lymphoblastic leukemia (BCP-ALL) treatment. However, this new armamentarium of therapies faces an old problem: choosing the right treatment for each patient. The lack of predictive biomarkers is particularly worrying for pediatric patients since it impairs the implementation of new treatments in the clinic. In this study, we used the functional assay dynamic BH3 profiling (DBP) to evaluate two new treatments for BCP-ALL that could improve clinical outcome, especially for relapsed patients. We found that the MEK inhibitor trametinib and the multi-target tyrosine kinase inhibitor sunitinib exquisitely increased apoptotic priming in an NRAS-mutant and in a KMT2A-rearranged cell line presenting a high expression of FLT3, respectively. Following these observations, we sought to study potential adaptations to these treatments. Indeed, we identified with DBP anti-apoptotic changes in the BCL-2 family after treatment, particularly involving MCL-1 – a pro-survival strategy previously observed in adult cancers. To overcome this adaptation, we employed the BH3 mimetic S63845, a specific MCL-1 inhibitor, and evaluated its sequential addition to both kinase inhibitors to overcome resistance. We observed that the metronomic combination of both drugs with S63845 was synergistic and showed an increased efficacy compared to single agents. Similar observations were made in BCP-ALL KMT2A-rearranged PDX cells in response to sunitinib, showing an analogous DBP profile to the SEM cell line. These findings demonstrate that rational sequences of targeted agents with BH3 mimetics, now extensively explored in clinical trials, may improve treatment effectiveness by overcoming anti-apoptotic adaptations in BCP-ALL.

JTD Keywords: apoptosis, bh3 mimetics, cancer, dependence, increases, kinase inhibition, pediatric leukemia, precision medicine, resistance, sensitivity, targeted therapies, tumor-cells, venetoclax, Apoptosis, Bcl-2 family proteins, Bh3 mimetics, Pediatric leukemia, Resistance, Targeted therapies

Biomimetic calcium-deficient hydroxyapatite (CDHA) as a bioactive material exhibits exceptional intrinsic osteoinductive and osteogenic properties because of its nanostructure and composition, which promote a favorable microenvironment. Its high reactivity has been hypothesized to play a relevant role in the in vivo performance, mediated by the interaction with the biological fluids, which is amplified by its high specific surface area. Paradoxically, this high reactivity is also behind the in vitro cytotoxicity of this material, especially pro-nounced in static conditions. The present work explores the structural and physicochemical changes that CDHA undergoes in contact with physiological fluids and to investigate its interaction with proteins. Calcium-deficient hydroxyapatite discs with different micro/nanostructures, coarse (C) and fine (F), were exposed to cell-free complete culture medium over extended periods of time: 1, 7, 14, 21, 28, and 50 days. Precipitate formation was not observed in any of the materials in contact with the physiological fluid, which would indicate that the ionic exchanges were linked to incorporation into the crystal structure of CDHA or in the hydrated layer. In fact, CDHA experienced a maturation process, with a progressive increase in crystallinity and the Ca/P ratio, accompanied by an uptake of Mg and a B-type carbonation process, with a gradual propagation into the core of the samples. However, the reactivity of biomimetic hydroxyapatite was highly dependent on the specific surface area and was amplified in nanosized needle-like crystal structures (F), whereas in coarse specimens the ionic exchanges were restricted to the surface, with low penetration in the material bulk. In addition to showing a higher protein adsorption on F substrates, the proteomics study revealed the existence of protein selectivity to-ward F or C microstructures, as well as the capability of CDHA, and more remarkably of F-CDHA, to concentrate specific proteins from the culture medium. Finally, a substantial improvement in the material's ability to support cell proliferation was observed after the CDHA maturation process.

JTD Keywords: calcium phosphates, ion exchange, nanostructure, protein adsorption, Biological-systems, Biomaterials, Biomimetic hydroxyapatites, Biomimetics, Bone-formation, Calcium deficient hydroxyapatite, Calcium phosphate, Calcium phosphates, Cell proliferation, Crystal structure, Crystallinity, Crystals structures, Culture medium, Growth, High reactivity, Hydroxyapatite, In-vitro, Ion exchange, Ionic exchange, Molecular biology, Nanocrystalline apatites, Nanostructure, Nanostructures, Octacalcium phosphate, Physicochemical studies, Physiological fluids, Physiology, Protein adsorption, Proteins, Proteomic studies, Raman spectroscopy, Serum-albumin, Specific surface area

Hybrid free-standing biomimetic materials are developed by integrating the VDAC36 β-barrel protein into robust and flexible three-layered polymer nanomembranes. The first and third layers are prepared by spin-coating a mixture of poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA). PVA nanofeatures are transformed into controlled nanoperforations by solvent-etching. The two nanoperforated PLA layers are separated by an electroactive layer, which is successfully electropolymerized by introducing a conducting sacrificial substrate under the first PLA nanosheet. Finally, the nanomaterial is consolidated by immobilizing the VDAC36 protein, active as an ion channel, into the nanoperforations of the upper layer. The integration of the protein causes a significant reduction of the material resistance, which decreases from 21.9 to 3.9 kΩ cm2. Electrochemical impedance spectroscopy studies using inorganic ions and molecular metabolites (i.e.l-lysine and ATP) not only reveal that the hybrid films behave as electrochemical supercapacitors but also indicate the most appropriate conditions to obtain selective responses against molecular ions as a function of their charge. The combination of polymers and proteins is promising for the development of new devices for engineering, biotechnological and biomedical applications.

JTD Keywords: channels, evolution, filter, Outer-membrane proteins

Abstract Purpose of the Review This review aims to summarize the current knowledge of the extracellular matrix remodeling during hepatic fibrosis. We discuss the diverse interactions of the extracellular matrix with hepatic cells and the surrounding matrix in liver fibrosis, with the focus on the molecular pathways and the mechanisms that regulate extracellular matrix remodeling. Recent Findings The extracellular matrix not only provides structure and support for the cells, but also controls cell behavior by providing adhesion signals and by acting as a reservoir of growth factors and cytokines. Summary Hepatic fibrosis is characterized by an excessive accumulation of extracellular matrix. During fibrogenesis, the natural remodeling process of the extracellular matrix varies, resulting in the excessive accumulation of its components, mainly collagens. Signals released by the extracellular matrix induce the activation of hepatic stellate cells, which are the major source of extracellular matrix and most abundant myofibroblasts in the liver. Graphical abstract

JTD Keywords: collagen, extracellular matrix, hepatic stellate cell, liver fibrosis, metalloproteinases, Tgf-?1, Tgf-β1

Synaptic plasticity involves structural modifications in dendritic spines that are modulated by local protein synthesis and actin remodeling. Here, we investigated the molecular mechanisms that connect synaptic stimulation to these processes. We found that the phosphorylation of isoform-specific sites in eEF1A2-an essential translation elongation factor in neurons-is a key modulator of structural plasticity in dendritic spines. Expression of a nonphosphorylatable eEF1A2 mutant stimulated mRNA translation but reduced actin dynamics and spine density. By contrast, a phosphomimetic eEF1A2 mutant exhibited decreased association with F-actin and was inactive as a translation elongation factor. Activation of metabotropic glutamate receptor signaling triggered transient dissociation of eEF1A2 from its regulatory guanine exchange factor (GEF) protein in dendritic spines in a phosphorylation-dependent manner. We propose that eEF1A2 establishes a cross-talk mechanism that coordinates translation and actin dynamics during spine remodeling.

JTD Keywords: cytoskeleton, expression, f-actin, factor 1-alpha, factor 1a, messenger-rna, nucleotide exchange, protein-synthesis, synaptic plasticity, Aminoacyl-transfer-rna

Cell response to force regulates essential processes in health and disease. However, the fundamental mechanical variables that cells sense and respond to remain unclear. Here we show that the rate of force application (loading rate) drives mechanosensing, as predicted by a molecular clutch model. By applying dynamic force regimes to cells through substrate stretching, optical tweezers, and atomic force microscopy, we find that increasing loading rates trigger talin-dependent mechanosensing, leading to adhesion growth and reinforcement, and YAP nuclear localization. However, above a given threshold the actin cytoskeleton softens, decreasing loading rates and preventing reinforcement. By stretching rat lungs in vivo, we show that a similar phenomenon may occur. Our results show that cell sensing of external forces and of passive mechanical parameters (like tissue stiffness) can be understood through the same mechanisms, driven by the properties under force of the mechanosensing molecules involved. Cells sense mechanical forces from their environment, but the precise mechanical variable sensed by cells is unclear. Here, the authors show that cells can sense the rate of force application, known as the loading rate, with effects on YAP nuclear localization and cytoskeletal stiffness remodelling.

JTD Keywords: Actin cytoskeleton, Actin filament, Actin-filament, Adhesion, Animal, Animals, Atomic force microscopy, Breathing, Cell, Cell adhesion, Cell culture, Cell nucleus, Cells, cultured, Cytoplasm, Extracellular-matrix, Fibroblast, Fibroblasts, Fibronectin, Frequency, Gene knockdown, Gene knockdown techniques, Genetics, Germfree animal, Integrin, Intracellular signaling peptides and proteins, Knockout mouse, Lung, Male, Mechanotransduction, Mechanotransduction, cellular, Metabolism, Mice, Mice, knockout, Microscopy, atomic force, Mouse, Optical tweezers, Paxillin, Physiology, Primary cell culture, Pxn protein, mouse, Rat, Rats, Rats, sprague-dawley, Respiration, Signal peptide, Softening, Specific pathogen-free organisms, Sprague dawley rat, Stress, Substrate, Substrate rigidity, Talin, Talin protein, mouse, Tln2 protein, mouse, Traction, Transmission, Ultrastructure, Yap1 protein, rat

Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures. Filamentous cable bacteria conduct electrical currents over centimeter distances through fibers embedded in their cell envelope. Here, Boschker et al. show that the fibers consist of a conductive core containing nickel proteins that is surrounded by an insulating protein shell.

JTD Keywords: Bacteria (microorganisms), Bacterial protein, Bacterial proteins, Bacterium, Chemistry, Deltaproteobacteria, Electric conductivity, Electricity, Electron, Electron transport, Metabolism, Microscopy, Nanowires, Nickel, Physiology, Protein, Resonance raman, Spectroscopy, Transport electrons

In this work we have explored the use of a Surface Plasmon resonance (SPR) phenomenon for the detection of interleukin-6 (IL-6), a pro-inflammatory cytokine. It plays an important role in the muscle tissues, having direct relation with muscle contraction and, thus, it is considered a biomarker for some types of muscular dystrophies. Here we show that SPR can be used as a real-time monitoring of the shift of the reflectance dip of a gold diffraction grating in front to the antibody adhesion to gold.

JTD Keywords: antibodies, gratings, interleukin-6 (il-6), proteins, Antibodies, Gratings, Interleukin-6 (il-6), Proteins, Surface plasmon resonance

Background & Aims: Prognostic models of cirrhosis underestimate disease severity for patients with cirrhosis and ascites. Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix protein linked to hepatic neoangiogenesis and fibrogenesis. We investigated ascites MFAP4 as a predictor of transplant-free survival in patients with cirrhosis and ascites. Methods: A dual-centre observational study of patients with cirrhosis and ascites recruited consecutively in relation to a paracentesis was carried out. Patients were followed up for 1 year, until death or liver transplantation (LTx). Ascites MFAP4 was tested with the model for end-stage liver disease (MELD-Na), CLIF Consortium Acute Decompensation (CLIF-C AD), and Child-Pugh score in Cox regression models. Results: Ninety-three patients requiring paracentesis were included. Median ascites MFAP4 was 29.7 U/L [22.3–41.3], and MELD-Na was 19 [16–23]. A low MELD-Na score (<20) was observed in 49 patients (53%). During follow-up, 20 patients died (22%), and 6 received LTx (6%). High ascites MFAP4 (>29.7 U/L) was associated with 1-year transplant-free survival (p = 0.002). In Cox regression, ascites MFAP4 and MELD-Na independently predicted 1-year transplant-free survival (hazard ratio [HR] = 0.97, p = 0.03, and HR = 1.08, p = 0.01, respectively). Ascites MFAP4 and CLIF-C AD also predicted survival independently (HR = 0.96, p = 0.02, and HR = 1.05, p = 0.03, respectively), whereas only ascites MFAP4 did, controlling for the Child-Pugh score (HR = 0.97, p = 0.03, and HR = 1.18, p = 0.16, respectively). For patients with MELD-Na <20, ascites MFAP4 but not ascites protein predicted 1-year transplant-free survival (HR 0.91, p = 0.02, and HR = 0.94, p = 0.17, respectively). Conclusions: Ascites MFAP4 predicts 1-year transplant-free survival in patients with cirrhosis and ascites. In patients with low MELD-Na scores, ascites MFAP4, but not total ascites protein, significantly predicted 1-year transplant-free survival. Lay summary: Patients with cirrhosis who have fluid in the abdomen, ascites, are at an increased risk of death and in need for liver transplantation. Our study identified patients with ascites and a poor prognosis by measuring microfibrillar associated protein 4 (MFAP4), a protein present in the abdominal fluid. Patients with low levels of the MFAP4 protein are at particularly increased risk of death or liver transplantation, suggesting that clinical care should be intensified in this group of patients. © 2021 The Authors

JTD Keywords: biomarker, clif-c ad, clif consortium acute decompensation, cps, child-pugh score, crp, c-reactive protein, ct, computed tomography, decompensated, ecm, extracellular matrix, fibrosis, fluid protein, gfr, glomerular filtration rate, hr, hazard ratio, inr, internationalised normal ratio, liver disease, liver-cirrhosis, ltx, liver transplantation, markers, meld-na, model for end-stage liver disease, mfap4, microfibrillar associated protein 4, mortality, nash, non-alcoholic steatohepatitis, natural-history, prognosis, risk-factors, sbp, spontaneous bacterial peritonitis, scores, stage, Biomarker, Decompensated, Egfr, estimated gfr, Fibrosis, Liver disease, Mortality, Prognosis, Spontaneous bacterial peritonitis

The extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway involves a three-step cascade of kinases that transduce signals and promote processes such as cell growth, development, and apoptosis. An aberrant response of this pathway is related to the proliferation of cell diseases and tumors. By using simulation modeling, we document that the protein arginine methyltransferase 5 (PRMT5) modulates the MAPK pathway and thus avoids an aberrant behavior. PRMT5 methylates the Raf kinase, reducing its catalytic activity and thereby, reducing the activation of ERK in time and amplitude. Two minimal computational models of the epidermal growth factor (EGF)-Ras-ERK MAPK pathway influenced by PRMT5 were proposed: a first model in which PRMT5 is activated by EGF and a second one in which PRMT5 is stimulated by the cascade response. The reported results show that PRMT5 reduces the time duration and the expression of the activated ERK in both cases, but only in the first model PRMT5 limits the EGF range that generates an ERK activation. Based on our data, we propose the protein PRMT5 as a regulatory factor to develop strategies to fight against an excessive activity of the MAPK pathway, which could be of use in chronic diseases and cancer.

JTD Keywords: cancer, cell response modulation, computational model, egf-ras-erk signaling route, mapk pathway, methylation, Arginine methyltransferase 5, Cancer, Cell response modulation, Colorectal-cancer, Computational model, Egf-ras-erk signaling route, Epidermal-growth-factor, Factor receptor, Histone h3, Kinase cascade, Mapk pathway, Methylation, Negative-feedback, Pc12 cells, Prmt5, Protein, Signal-transduction

Significance: The incidence of chronic wounds is increasing due to our aging population and the augment of people afflicted with diabetes. With the extended knowledge on the biological mechanisms underlying these diseases, there is a novel influx of medical technologies into the conventional wound care market. Recent Advances: Several nanotechnologies have been developed demonstrating unique characteristics that address specific problems related to wound repair mechanisms. In this review, we focus on the most recently developed nanotechnology-based therapeutic agents and evaluate the efficacy of each treatment in in vivo diabetic models of chronic wound healing. Critical Issues: Despite the development of potential biomaterials and nanotechnology-based applications for wound healing, this scientific knowledge is not translated into an increase of commercially available wound healing products containing nanomaterials. Future Directions: Further studies are critical to provide insights into how scientific evidences from nanotechnology-based therapies can be applied in the clinical setting.

JTD Keywords: chronic, diabetes, liposomes, nanofibers, nanoparticles, Chronic, Chronic wound, Diabetes, Diabetic wound, Diabetic-rats, Dressings, Drug mechanism, Extracellular-matrix, Growth-factor, Human, In-vitro, Liposome, Liposomes, Mesenchymal stem-cells, Metal nanoparticle, Nanofiber, Nanofibers, Nanofibrous scaffolds, Nanoparticles, Nanotechnology, Nonhuman, Polyester, Polymer, Polysaccharide, Priority journal, Protein, Review, Self assembled protein nanoparticle, Silk fibroin, Skin wounds, Wound healing, Wound healing promoting agent

The exponential increase of waste derived from different human activities points out the importance of their reuse in order to create materials with specific properties that can be used for different applications. In this work, it was showed how the typical Mediterranean organic liquid waste, namely olive mill wastewater (OMWW), obtained during olive oil production, can be turned into an efficient reactive agent for the production of noble metals gold (Au) and silver nanoparticles (Ag NPs) with very well-defined physico-chemical properties. More than that, it was demonstrated that this synthetic procedure also leads to a drastic decrease of the organic pollution load of the OMWW, making it safer for environmental disposal and plants irrigation. Then, using healthy hepatic cell line mitochondria, the biological effects induced by these green metal NPs surrounded by a polyphenols shell, with the same NPs synthetized through a standard chemical colloidal reduction process, were compared, finding out that the green NPs are much safer.

JTD Keywords: antioxidants perturbation, green synthesis, gtpase dynamin-related protein 1 expression, mitochondria assessment, physico-chemical properties, Antioxidants perturbation, Green synthesis, Gtpase dynamin-related protein 1 expression, Mitochondria assessment, Physico-chemical properties, Reusability of waste

Tau protein is largely responsible for tauopathies, including Alzheimer’s disease (AD), where it accumulates in the brain as insoluble aggregates. Tau mRNA is regulated by alternative splicing, and inclusion or exclusion of exon 10 gives rise to the 3R and 4R isoforms respectively, whose balance is physiologically regulated. In this sense, one of the several factors that regulate alternative splicing of tau is GSK3?, whose activity is inhibited by the cellular prion protein (PrPC), which has different physiological functions in neuroprotection and neuronal differentiation. Moreover, a relationship between PrPC and tau expression levels has been reported during AD evolution. For this reason, in this study we aimed to analyze the role of PrPC and the implication of GSK3? in the regulation of tau exon 10 alternative splicing. We used AD human samples and mouse models of PrPC ablation and tau overexpression. In addition, we used primary neuronal cultures to develop functional studies. Our results revealed a paralleled association between PrPC expression and tau 4R isoforms in all models analyzed. In this sense, reduction or ablation of PrPC levels induces an increase in tau 3R/4R balance. More relevantly, our data points to GSK3? activity downstream from PrPC in this phenomenon. Our results indicate that PrPC plays a role in tau exon 10 inclusion through the inhibitory capacity of GSK3?. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: alternative splicing, alzheimer's disease, alzheimers-disease, alzheimer’s disease, amyloid-beta, cellular prion protein, frontotemporal dementia, glycogen-synthase kinase-3, gsk3 beta, gsk3?, gsk3β, messenger-rna, microtubule-associated protein tau, neurofibrillary tangles, progressive supranuclear palsy, promotes neuronal differentiation, stem-cells, tauopathies, Alternative splicing, Alzheimer’s disease, Cellular prion protein, Gsk3?, Microtubule-associated protein tau, Tauopathies

The low efficacy of current conventional treatments for bacterial infections increases mortality rates worldwide. To alleviate this global health problem, we propose drug-free enzyme-based nanomotors for the treatment of bacterial urinary-tract infections. We develop nanomotors consisting of mesoporous silica nanoparticles (MSNPs) that were functionalized with either urease (U-MSNPs), lysozyme (L-MSNPs), or urease and lysozyme (M-MSNPs), and use them against nonpathogenic planktonic Escherichia coli. U-MSNPs exhibited the highest bactericidal activity due to biocatalysis of urea into NaHCO3 and NH3, which also propels U-MSNPs. In addition, U-MSNPs in concentrations above 200 μg/mL were capable of successfully reducing 60% of the biofilm biomass of a uropathogenic E. coli strain. This study thus provides a proof-of-concept, demonstrating that enzyme-based nanomotors are capable of fighting infectious diseases. This approach could potentially be extended to other kinds of diseases by selecting appropriate biomolecules.

JTD Keywords: biofilms, carbonate, e. coli, enzymatic nanomotors, infections, lysozyme, micromotors, nanomachines, proteins, self-propulsion, Biofilms, E. coli, Eliminate escherichia-coli, Enzymatic nanomotors, Infections, Nanomachines, Self-propulsion

© 2020 Elsevier Ltd Protein phase transitions are particularly amenable for cell signalling as these highly cooperative processes allow cells to make binary decisions in response to relatively small intracellular changes. The different processes of condensate formation and the distinct material properties of the resulting condensates provide a dictionary to modulate a range of decisions on cell fate. We argue that, on the one hand, the reversibility of liquid demixing offers a chance to arrest cell growth under specific circumstances. On the other hand, the transition to amyloids is better suited for terminal decisions such as those leading to apoptosis and necrosis. Here, we review recent examples of both scenarios, highlighting how mutations in signalling proteins affect the formation of biomolecular condensates with drastic effects on cell survival.

JTD Keywords: amyloid, cell death, deep mutagenesis, llps, rna-binding proteins, Amyloid, Cell death, Deep mutagenesis, Llps, Rna-binding proteins

Background & Aims: MicroRNAs (miRNAs) circulate in several body fluids and can be useful biomarkers. The aim of this study was to identify blood-circulating miRNAs associated with cirrhosis progression and acute-on-chronic liver failure (ACLF). Methods: Using high-throughput screening of 754 miRNAs, serum samples from 45 patients with compensated cirrhosis, decompensated cirrhosis, or ACLF were compared with those from healthy individuals (n = 15). miRNA levels were correlated with clinical parameters, organ failure, and disease progression and outcome. Dysregulated miRNAs were evaluated in portal and hepatic vein samples (n = 33), liver tissues (n = 17), and peripheral blood mononuclear cells (PBMCs) (n = 16). Results: miRNA screening analysis revealed that circulating miRNAs are dysregulated in cirrhosis progression, with 51 miRNAs being differentially expressed among all groups of patients. Unsupervised clustering and principal component analysis indicated that the main differences in miRNA expression occurred at decompensation, showing similar levels in patients with decompensated cirrhosis and those with ACLF. Of 43 selected miRNAs examined for differences among groups, 10 were differentially expressed according to disease progression. Moreover, 20 circulating miRNAs were correlated with model for end-stage liver disease and Child-Pugh scores. Notably, 11 dysregulated miRNAs were associated with kidney or liver failure, encephalopathy, bacterial infection, and poor outcomes. The most severely dysregulated miRNAs (i.e. miR-146a5p, miR-26a-5p, and miR-191-5p) were further evaluated in portal and hepatic vein blood and liver tissue, but showed no differences. However, PBMCs from patients with cirrhosis showed significant downregulation of miR-26 and miR-146a, suggesting a extrahepatic origin of some circulating miRNAs. Conclusions: This study is a repository of circulating miRNA data following cirrhosis progression and ACLF. Circulating miRNAs were profoundly dysregulated during the progression of chronic liver disease, were associated with failure of several organs and could have prognostic utility. Lay summary: Circulating miRNAs are small molecules in the blood that can be used to identify or predict a clinical condition. Our study aimed to identify miRNAs for use as biomarkers in patients with cirrhosis or acute-on-chronic liver failure. Several miRNAs were found to be dysregulated during the progression of disease, and some were also related to organ failure and disease-related outcomes. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of European Association for the Study of the Liver (EASL).

JTD Keywords: aclf, acute-on-chronic liver failure, alt, alanine aminotransferase, ast, aspartate aminotransferase, biomarkers, chronic liver disease, cxcl10, c-x-c motif chemokine ligand 10, ef clif, european foundation for the study of chronic liver failure, foxo, forkhead box o, inr, international normalised ratio, ldh, lactate dehydrogenase, liver decompensation, mapk, mitogen-activated protein kinase, meld, model for end-stage liver disease, nash, non-alcoholic steatohepatitis, non-coding rnas, pbmcs, peripheral blood mononuclear cells, pca, principal component analysis, tgf, transforming growth factor, tips, transjugular intrahepatic portosystemic shunt, Biomarkers, Chronic liver disease, Expression, Liver decompensation, Markers, Mir-146a, Non-coding rnas, Qpcr, quantitative pcr

JTD Keywords: cardiac-hypertrophy, heart, mechanisms, Protein-kinase-d

© 2020 Elsevier Inc. Correlative light and electron microscopy (CLEM) entails a group of multimodal imaging techniques that are combined to pinpoint to the location of fluorescently labeled molecules in the context of their ultrastructural cellular environment. Here we describe a detailed workflow for STORM-CLEM, in which STochastic Optical Reconstruction Microscopy (STORM), an optical super-resolution technique, is correlated with transmission electron microscopy (TEM). This protocol has the advantage that both imaging modalities have resolution at the nanoscale, bringing higher synergies on the information obtained. The sample is prepared according to the Tokuyasu method followed by click-chemistry labeling and STORM imaging. Then, after heavy metal staining, electron microscopy imaging is performed followed by correlation of the two images. The case study presented here is on intracellular pathogens, but the protocol is versatile and could potentially be applied to many types of samples.

JTD Keywords: cells, click-chemistry, complex, correlative light and electron microscopy, cycloaddition, ligation, localization, proteins, resolution limit, single molecule localization microscopy, stochastic optical reconstruction microscopy (storm), storm, super-resolution microscopy, tokuyasu cryo-sectioning, tool, Click-chemistry, Correlative light and electron microscopy, Fluorescent-probes, Single molecule localization microscopy, Stochastic optical reconstruction microscopy (storm), Super-resolution microscopy, Tokuyasu cryo-sectioning, Transmission electron microscopy

© 2020 The Authors. Advanced Science published by Wiley-VCH GmbH The establishment of tumor microenvironment using biomimetic in vitro models that recapitulate key tumor hallmarks including the tumor supporting extracellular matrix (ECM) is in high demand for accelerating the discovery and preclinical validation of more effective anticancer therapeutics. To date, ECM-mimetic hydrogels have been widely explored for 3D in vitro disease modeling owing to their bioactive properties that can be further adapted to the biochemical and biophysical properties of native tumors. Gathering on this momentum, herein the current landscape of intrinsically bioactive protein and peptide hydrogels that have been employed for 3D tumor modeling are discussed. Initially, the importance of recreating such microenvironment and the main considerations for generating ECM-mimetic 3D hydrogel in vitro tumor models are showcased. A comprehensive discussion focusing protein, peptide, or hybrid ECM-mimetic platforms employed for modeling cancer cells/stroma cross-talk and for the preclinical evaluation of candidate anticancer therapies is also provided. Further development of tumor-tunable, proteinaceous or peptide 3D microtesting platforms with microenvironment-specific biophysical and biomolecular cues will contribute to better mimic the in vivo scenario, and improve the predictability of preclinical screening of generalized or personalized therapeutics.

JTD Keywords: 3d in vitro models, cancers, hydrogels, peptides, 3d in vitro models, Cancers, Hydrogels, Peptides, Proteins

© 2020 The Authors Although the concept of selective delivery has been postulated over 100 years ago, no targeted nanomedicine has been clinically approved so far. Nanoparticles modified with targeting ligands to promote the selective delivery of therapeutics towards a specific cell population have been extensively reported. However, the rational design of selective particles is still challenging. One of the main reasons for this is the lack of quantitative theoretical and experimental understanding of the interactions involved in cell targeting. In this review, we discuss new theoretical models and experimental methods that provide a quantitative view of targeting. We show the new advancements in multivalency theory enabling the rational design of super-selective nanoparticles. Furthermore, we present the innovative approaches to obtain key targeting parameters at the single-cell and single molecule level and their role in the design of targeting nanoparticles. We believe that the combination of new theoretical multivalent design and experimental methods to quantify receptors and ligands aids in the rational design and clinical translation of targeted nanomedicines.

JTD Keywords: binding-kinetics, biological identity, biomolecular corona, blood-brain-barrier, drug-delivery, gold nanoparticles, multivalency, nanotechnology, protein corona, quantitative characterization, rational design, super-selectivity, superresolution microscopy, tumor heterogeneity, Ligand-receptor interactions, Multivalency, Nanotechnology, Quantitative characterization, Rational design, Super-selectivity

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. Achieving intracellular delivery of protein therapeutics within cells remains a significant challenge. Although custom formulations are available for some protein therapeutics, the development of non‐toxic delivery systems that can incorporate a variety of active protein cargo and maintain their stability, is a topic of great relevance. This study utilized ionic polyphosphazenes (PZ) that can assemble into supramolecular complexes through non‐covalent interactions with different types of protein cargo. We tested a PEGylated graft copolymer (PZ‐PEG) and a pyrrolidone containing linear derivative (PZ‐PYR) for their ability to intracellularly deliver FITC‐avidin, a model protein. In endothelial cells, PZ‐PYR/protein exhibited both faster internalization and higher uptake levels than PZ‐PEG/protein, while in cancer cells both polymers achieved similar uptake levels over time, although the internalization rate was slower for PZ‐PYR/protein. Uptake was mediated by endocytosis through multiple mechanisms, PZ‐PEG/avidin colocalized more profusely with endo-lysosomes, and PZ‐PYR/avidin achieved greater cytosolic delivery. Consequently, a PZ‐PYR-delivered anti‐F‐actin antibody was able to bind to cytosolic actin filaments without needing cell permeabilization. Similarly, a cell‐impermeable Bax‐BH3 peptide known to induce apoptosis, decreased cell viability when complexed with PZ‐PYR, demonstrating endo‐lysosomal escape. These biodegradable PZs were non‐toxic to cells and represent a promising platform for drug delivery of protein therapeutics.

JTD Keywords: cytosolic delivery, cytotoxicity, delivery of apoptotic peptides, endosomal escape, intracellular delivery of antibody, intracellular protein delivery, Cytosolic delivery, Cytotoxicity, Delivery of apoptotic peptides, Endosomal escape, Intracellular delivery of antibody, Intracellular protein delivery, Polyphosphazene polymers

Plaques of the amyloid beta (A beta) peptide are a pathological hallmark of Alzheimer's disease (AD), the most common form of dementia. Mutations in A beta also cause familial forms of AD (fAD). Here, we use deep mutational scanning to quantify the effects of >14,000 mutations on the aggregation of A beta. The resulting genetic landscape reveals mechanistic insights into fibril nucleation, including the importance of charge and gatekeeper residues in the disordered region outside of the amyloid core in preventing nucleation. Strikingly, unlike computational predictors and previous measurements, the empirical nucleation scores accurately identify all known dominant fAD mutations in A beta, genetically validating that the mechanism of nucleation in a cell-based assay is likely to be very similar to the mechanism that causes the human disease. These results provide the first comprehensive atlas of how mutations alter the formation of any amyloid fibril and a resource for the interpretation of genetic variation in A beta.

JTD Keywords: aggregation, kinetics, oligomers, onset, rates, state, Aggregation, Alzheimer's, Amyloid, Computational biology, Deep mutagenesis, Genetics, Genomics, Kinetics, Nucleation, Oligomers, Onset, Precursor protein, Rates, S. cerevisiae, State, Systems biology

Rapid spread of SARS-CoV-2 virus have boosted the need of knowledge about inactivation mechanisms to minimize the impact of COVID-19 pandemic. Recent studies have shown that SARS-CoV-2 virus can be disabled by heating, the exposure time for total inactivation depending on the reached temperature (e.g. more than 45 min at 329 K or less than 5 min at 373 K. In spite of recent crystallographic structures, little is known about the molecular changes induced by the temperature. Here, we unravel the molecular basis of the effect of the temperature over the SARS-CoV-2 spike glycoprotein, which is a homotrimer with three identical monomers, by executing atomistic molecular dynamics (MD) simulations at 298, 310, 324, 338, 358 and 373 K. Furthermore, both the closed down and open up conformational states, which affect the accessibility of receptor binding domain, have been considered. Our results suggest that the spike homotrimer undergoes drastic changes in the topology of the hydrogen bonding interactions and important changes on the secondary structure of the receptor binding domain (RBD), while electrostatic interactions (i.e. salt bridges) are mainly preserved. The proposed inactivation mechanism has important implications for engineering new approaches to fight the SARS-CoV-2 coronavirus, as for example, cleaving or reorganizing the hydrogen bonds through chaotropic agents or nanoparticles with local surface resonant plasmon effect.

JTD Keywords: atomistic simulations, coronaviruses, denaturation, homotrimeric protein, inactivation, proteins, receptor binding domain, salt bridges, simulation, thermal inactivation, virus spike, Atomistic simulations, Homotrimeric protein, Receptor binding domain, Secondary-structure, Thermal inactivation, Virus spike

Goel and colleagues show that CDK4/6 inhibition induces global chromatin changes mediated by AP-1 factors, which mediate key biological and clinical effects in breast cancer. Pharmacologic inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6) were designed to induce cancer cell cycle arrest. Recent studies have suggested that these agents also exert other effects, influencing cancer cell immunogenicity, apoptotic responses and differentiation. Using cell-based and mouse models of breast cancer together with clinical specimens, we show that CDK4/6 inhibitors induce remodeling of cancer cell chromatin characterized by widespread enhancer activation, and that this explains many of these effects. The newly activated enhancers include classical super-enhancers that drive luminal differentiation and apoptotic evasion, as well as a set of enhancers overlying endogenous retroviral elements that are enriched for proximity to interferon-driven genes. Mechanistically, CDK4/6 inhibition increases the level of several activator protein-1 transcription factor proteins, which are in turn implicated in the activity of many of the new enhancers. Our findings offer insights into CDK4/6 pathway biology and should inform the future development of CDK4/6 inhibitors.

JTD Keywords: Abemaciclib, Androgen receptor, Animal experiment, Animal model, Animal tissue, Apoptosis, Article, Breast cancer, C-jun, Cancer cell, Carcinoembryonic antigen related cell adhesion molecule 1, Caspase 3, Cell cycle arrest, Cells, Chromatin, Chromatin immunoprecipitation, Controlled study, Cyclin dependent kinase 4, Cyclin dependent kinase 6, Dna damage, Epidermal growth factor receptor 2, Estrogen receptor, Female, Flow cytometry, Fulvestrant, Hla drb1 antigen, Human, Human cell, Immunoblotting, Immunogenicity, Immunoprecipitation, Interferon, Luciferase assay, Mcf-7 cell line, Mda-mb-231 cell line, Microarray analysis, Morphogenesis, Mouse, Nonhuman, Palbociclib, Protein, Protein expression, Rb, Resistance, Rna polymerase ii, Rna sequence, Selective-inhibition, Senescence, Short tandem repeat, Signal transduction, Tamoxifen, Transcription elongation, Transcription factor, Transcription factor ap 1, Transcriptome, Tumor biopsy, Tumor differentiation, Tumor spheroid, Tumor xenograft, Vinculin, Whole exome sequencing

Engineered immunoglobulin-G molecules (IgGs) are of wide interest for the development of detection elements in protein-based biosensors with clinical applications. The strategy usually employed for the de novo design of such engineered IgGs consists on merging fragments of the three-dimensional structure of a native IgG, which is immobilized on the biosensor surface, and of an antibody with an exquisite target specificity and affinity. In this work conventional and accelerated classical molecular dynamics (cMD and aMD, respectively) simulations have been used to propose two IgG-like antibodies for COVID-19 detection. More specifically, the crystal structure of the IgG1 B12 antibody, which inactivates the human immunodeficiency virus-1, has been merged with the structure of the antibody CR3022 Fab tightly bounded to SARS-CoV-2 receptor-binding domain (RBD) and the structure of the 5309 antibody Fab fragment complexed with SARS-CoV-2 RBD. The two constructed antibodies, named IgG1-CR3022 and IgG1-S309, respectively, have been immobilized on a stable gold surface through a linker. Analyses of the influence of both the merging strategy and the substrate on the stability of the two constructs indicate that the IgG1-S309 antibody better preserves the neutralizing structure than the IgG1-CR3022 one. Overall, results indicate that the IgG1-S309 is appropriated for the generation of antibody based sensors for COVID-19 diagnosis. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.

JTD Keywords: cr3022, igg1, molecular engineering, s309, Antibodies, Antibody engineering, Biosensors, Chemical detection, Clinical application, Cov, Cr3022, Crystal structure, Design, Diseases, Gold nanoparticles, Igg1, Igg1 antibody, Immobilization, Immunoglobulin g, Immunosensor, In-silico, Merging, Molecular dynamics, Molecular engineering, Orientation, Protein-based biosensors, Receptor-binding domains, S309, Sars, Sensor, Spike protein, Target, Vaccine, Viruses

The rapid evolution of resistance in the malaria parasite to every single drug developed against it calls for the urgent identification of new molecular targets. Using a stain specific for the detection of intracellular amyloid deposits in live cells, we have detected the presence of abundant protein aggregates in Plasmodium falciparum blood stages and female gametes cultured in vitro, in the blood stages of mice infected by Plasmodium yoelii, and in the mosquito stages of the murine malaria species Plasmodium berghei. Aggregated proteins could not be detected in early rings, the parasite form that starts the intraerythrocytic cycle. A proteomics approach was used to pinpoint actual aggregating polypeptides in functional P. falciparum blood stages, which resulted in the identification of 369 proteins, with roles particularly enriched in nuclear import-related processes. Five aggregation-prone short peptides selected from this protein pool exhibited different aggregation propensity according to Thioflavin-T fluorescence measurements, and were observed to form amorphous aggregates and amyloid fibrils in transmission electron microscope images. The results presented suggest that generalized protein aggregation might have a functional role in malaria parasites. Future antimalarial strategies based on the upsetting of the pathogen’s proteostasis and therefore affecting multiple gene products could represent the entry to new therapeutic approaches

JTD Keywords: Malaria, Protein aggregation

The transport of metabolites across robust, flexible and free-standing biomimetic membranes made of three perforated poly (lactic acid) (pPLA) layers, separated by two anodically polymerized conducting layers of poly (3,4-ethylenedioxythiophene-co-3-dodecylthiophene), and functionalized on the external pPLA layers with a voltage dependent anion channel (VDAC) protein, has been demonstrated. The three pPLA layers offer robustness and flexibility to the bioactive platform and the possibility of obtaining conducing polymer layers by in situ anodic polymerization. The incorporation of dodecylthiophene units, which bear a 12 carbon atoms long linear alkyl chain, to the conducting layers allows mimicking the amphiphilic environment offered by lipids in cells, increasing 32% the efficiency of the functionalization. Electrochemical impedance measurements in NaCl and adenosine triphosphate (ATP) solutions prove that the integration of the VDAC porin inside the PLA perforations considerably increases the membrane conductivity and is crucial for the electrolyte diffusion. Such results open the door for the development of advanced sensing devices for a broad panel of biomedical applications.

JTD Keywords: Conducting polymers, Membrane proteins, Membranes, Polylactic acid, Self-supported films

We have previously provided the first genetic evidence that angiotensin converting enzyme 2 (ACE2) is the critical receptor for severe acute respiratory syndrome coronavirus (SARS-CoV), and ACE2 protects the lung from injury, providing a molecular explanation for the severe lung failure and death due to SARS-CoV infections. ACE2 has now also been identified as a key receptor for SARS-CoV-2 infections, and it has been proposed that inhibiting this interaction might be used in treating patients with COVID-19. However, it is not known whether human recombinant soluble ACE2 (hrsACE2) blocks growth of SARS-CoV-2. Here, we show that clinical grade hrsACE2 reduced SARS-CoV-2 recovery from Vero cells by a factor of 1,000-5,000. An equivalent mouse rsACE2 had no effect. We also show that SARS-CoV-2 can directly infect engineered human blood vessel organoids and human kidney organoids, which can be inhibited by hrsACE2. These data demonstrate that hrsACE2 can significantly block early stages of SARS-CoV-2 infections.

JTD Keywords: COVID-19, Angiotensin converting enzyme 2, Blood vessels, Human organoids, Kidney, Severe acute respiratory syndrome coronavirus, Spike glycoproteins, Treatment

Bone morphogenetic proteins (BMPs) are secreted growth factors that belong to the transforming growth factor beta superfamily. BMPs have been implicated in physiological processes, but they are also involved in many pathological conditions. Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS); however, its etiology remains elusive. Some evidence points to BMPs as important players in the pathogenesis of inflammatory and autoimmune disorders. In the present work, we studied the expression of BMP2, BMP4, BMP5, BMP6, BMP7, BMP type II receptor, and noggin in the immune system during different phases of experimental autoimmune encephalomyelitis (EAE). Major changes in the expression of BMPs took place in the initial phases of EAE. Indeed, those changes mainly affected BMP6 (whose expression was abrogated), BMP2, and BMP7 (whose expression was increased). In addition, we showed that in vivo inhibition of the BMP signaling pathway with small molecules ameliorated the already established clinical symptoms of EAE, as well as the CNS histopathological features. At the immune level, we observed an expansion of plasmacytoid dendritic cells (pDCs) in mice treated with small molecules that inhibit the BMP signaling pathway. pDCs could play an important role in promoting the expansion of antigen-specific regulatory T cells. Altogether, our data suggest a role for BMPs in early immune events that take place in myelin oligodendrocyte glycoprotein (MOG)-induced EAE. In addition, the clinical outcome of the disease was improved when the BMP signaling pathway was inhibited in mice that presented established EAE symptoms.

JTD Keywords: Bone morphogenetic protein, DMH1, Dorsomorphin, Experimental autoimmune encephalomyelitis, Immune response, Multiple sclerosis.

Background: Alcoholic liver disease (ALD) is a public health concern that is the cause of half of all cirrhosis-related deaths. Early detection of fibrosis, ideally in the precirrhotic stage, is a key strategy for improving ALD outcomes and for preventing progression to cirrhosis. Previous studies identified the blood-borne marker human microfibrillar-associated protein 4 (MFAP4) as a biomarker for detection of hepatitis C virus (HCV)-related fibrosis. Aim: To evaluate the diagnostic accuracy of MFAP4 to detect ALD-induced fibrosis. Method: We performed a prospective, liver biopsy-controlled study involving 266 patients with prior or current alcohol overuse. Patients were split into a training and a validation cohort. Results: MFAP4 was present in fibrotic hepatic tissue and serum MFAP4 levels increased with fibrosis grade. The area under the receiver operating characteristic curve (AUROC) for detection of cirrhosis was 0.91 (95% CI 0.85-0.96) in the training cohort and 0.91 (95% CI 0.79-1.00) in the validation cohort. For detection of advanced fibrosis, the AUROC was 0.88 (95% CI 0.81-0.94) in the training cohort and 0.92 (95% CI 0.83-1.00) in the validation cohort. The diagnostic accuracy did not differ between MFAP4 and the enhanced liver fibrosis (ELF) test or transient elastography (TE) in an intention-to-diagnose analysis. MFAP4 did not predict hepatic decompensation in a time-to-decompensation analysis in a subgroup of patients with cirrhosis. Conclusion: MFAP4 is a novel biomarker that can detect ALD-related fibrosis with high accuracy.

JTD Keywords: Biomarker, Cirrhosis, Extracellular matrix protein, Liver biopsy, Non-invasive testing

Within the brain, endothelial cells lining the blood vessels meticulously coordinate the transport of nutrients, energy metabolites and other macromolecules essential in maintaining an appropriate activity of the brain. While small molecules are pumped across specialised molecular transporters, large macromolecular cargos are shuttled from one side to the other through membrane-bound carriers formed by endocytosis on one side, trafficked to the other side and released by exocytosis. Such a process is collectively known as transcytosis. The brain endothelium is recognised to possess an intricate vesicular endosomal network that mediates the transcellular transport of cargos from blood-to-brain and brain-to-blood. However, mounting evidence suggests that brain endothelial cells (BECs) employ a more direct route via tubular carriers for a fast and efficient transport from the blood to the brain. Here, we compile the mechanism of transcytosis in BECs, in which we highlight intracellular trafficking mediated by tubulation, and emphasise the possible role in transcytosis of the Bin/Amphiphysin/Rvs (BAR) proteins and glycocalyx (GC)-a layer of sugars covering BECs, in transcytosis. Both BAR proteins and the GC are intrinsically associated with cell membranes and involved in the modulation and shaping of these membranes. Hence, we aim to summarise the machinery involved in transcytosis in BECs and highlight an uncovered role of BAR proteins and the GC at the brain endothelium.

JTD Keywords: BAR proteins, Blood-brain barrier, Endothelium, Glycocalyx, Transcytosis, Tubulation

Background & Aims: Renal function assessed by creatinine is a key prognostic factor in cirrhotic patients. However, creatinine is influenced by several factors, rendering interpretation difficult in some situations. This is especially important in early stages of renal dysfunction where renal impairment might not be accompanied by an increase in creatinine. Other parameters, such as cystatin C (CysC) and beta‐trace protein (BTP), have been evaluated to fill this gap. However, none of these studies have considered the role of the patient's sex. The present study analysed CysC and BTP to evaluate their prognostic value and differentiate them according to sex. Patients and methods: CysC and BTP were measured in 173 transjugular intrahepatic portosystemic shunt (TIPS)-patients from the NEPTUN-STUDY(NCT03628807) and analysed their relationship with mortality and sex. Propensity score for age, MELD, etiology and TIPS indication was used. Results: Cystatin C and BTP showed excellent correlations with creatinine values at baseline and follow-up. CysC was an independent predictor of overall mortality (HR = 1.66(1.33-2.06)) with an AUC of 0.75 and identified a cut-off of 1.55 mg/L in the whole cohort. Interestingly, CysC was significantly lower in females, also after propensity score matching. In males, the only independent predictor was the creatinine level (HR = 1.54(1.25-1.58)), while in females CysC levels independently predicted mortality (HR = 3.17(1.34-7.52)). Conclusion: This study demonstrates for the first time that in TIPS-patients creatinine predicts mortality in males better than in females, whereas CysC is a better predictor of mortality in females. These results may influence future clinical decisions on therapeutic options for example, allocation for liver transplantation in TIPS-patients.

JTD Keywords: Beta-trace protein, Cirrhosis, Cystatin C, Portal hypertension, Renal function

Cellular prion protein (PrPC) is largely responsible for transmissible spongiform encephalopathies (TSEs) when it becomes the abnormally processed and protease resistant form PrPSC. Physiological functions of PrPC include protective roles against oxidative stress and excitotoxicity. Relevantly, PrPC downregulates tau levels, whose accumulation and modification are a hallmark in the advance of Alzheimer's disease (AD). In addition to the accumulation of misfolded proteins, in the initial stages of AD-affected brains display both increased reactive oxygen species (ROS) markers and levels of PrPC. However, the factors responsible for the upregulation of PrPC are unknown. Thus, the aim of this study was to uncover the different molecular actors promoting PrPC overexpression. In order to mimic early stages of AD, we used β-amyloid-derived diffusible ligands (ADDLs) and tau cellular treatments, as well as ROS generation, to elucidate their particular roles in human PRNP promoter activity. In addition, we used specific chemical inhibitors and site-specific mutations of the PRNP promoter sequence to analyze the contribution of the main transcription factors involved in PRNP transcription under the analyzed conditions. Our results revealed that tau is a new modulator of PrPC expression independently of ADDL treatment and ROS levels. Lastly, we discovered that the JNK/c-jun-AP-1 pathway is involved in increased PRNP transcription activity by tau but not in the promoter response to ROS.

JTD Keywords: Alzheimer’s disease, Cellular prion protein, Promoter, Tau, Tauopathies

Titanium (Ti) and Ti alloys have been used for decades for bone prostheses due to its mechanical reliability and good biocompatibility. However, the high stiffness of Ti implants and the lack of bioactivity are pending issues that should be improved to minimize implant failure. The stress shielding effect, a result of the stiffness mismatch between titanium and bone, can be reduced by introducing a tailored structural porosity in the implant. In this work, porous titanium structures were produced by direct ink writing (DIW), using a new Ti ink formulation containing a thermosensitive hydrogel. A thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process, in order to avoid contamination of the titanium structures. The samples were sintered in argon atmosphere at 1200 °C, 1300 °C or 1400 °C, resulting in total porosities ranging between 72.3% and 77.7%. A correlation was found between the total porosity and the elastic modulus of the scaffolds. The stiffness and yield strength were similar to those of cancellous bone. The functionalization of the scaffold surface with a cell adhesion fibronectin recombinant fragment resulted in enhanced adhesion and spreading of osteoblastic-like cells, together with increased alkaline phosphatase expression and mineralization.

JTD Keywords: Direct ink writing, Osseointegration, Recombinant protein, Thermoresponsive binder, Titanium, Titanium scaffold

Installing bioactivity on metallic biomaterials by mimicking the extracellular matrix (ECM) is crucial for stimulating specific cellular responses to ultimately promote tissue regeneration. Fibronectin is an ECM protein commonly used for biomaterial functionalization. The use of fibronectin recombinant fragments is an attractive alternate to the use of full-length fibronectin because of the relatively low cost and facility of purification. However, it is necessary to combine more than one fragment, for example, the cell attachment site and the heparin binding II (HBII), either mixed or in one molecule, to obtain complete activity. In the present study, we proposed to install adhesion capacity to the HBII fragment by an RGD gain-of-function DNA mutation, retaining its cell differentiation capacity and thereby producing a small and very active protein fragment. The novel molecule, covalently immobilized onto titanium surfaces, maintained the growth factor-binding capacity and stimulated cell spreading, osteoblastic cell differentiation, and mineralization of human mesenchymal stem cells compared to the HBII native protein. These results highlight the potential capacity of gain-of-function DNA mutations in the design of novel molecules for the improvement of osseointegration properties of metallic implant surfaces.

JTD Keywords: Fibronectin, Growth factor, Mutation, Osseointegration, Recombinant protein, Titanium

Non-alcoholic fatty liver disease (NAFLD) is characterized by lipid accumulation within the liver affecting 1 in 4 people worldwide. As the new silent killer of the twenty-first century, NAFLD impacts on both the request and the availability of new liver donors. The liver is the first line of defense against endogenous and exogenous metabolites and toxins. It also retains the ability to switch between different metabolic pathways according to food type and availability. This ability becomes a disadvantage in obesogenic societies where most people choose a diet based on fats and carbohydrates while ignoring vitamins and fiber. The chronic exposure to fats and carbohydrates induces dramatic changes in the liver zonation and triggers the development of insulin resistance. Common believes on NAFLD and different diets are based either on epidemiological studies, or meta-analysis, which are not controlled evidences; in most of the cases, they are biased on test-subject type and their lifestyles. The highest success in reverting NAFLD can be attributed to diets based on high protein instead of carbohydrates. In this review, we discuss the impact of NAFLD on body metabolic plasticity. We also present a detailed analysis of the most recent studies that evaluate high-protein diets in NAFLD with a special focus on the liver and the skeletal muscle protein metabolisms.

JTD Keywords: High protein diet, Low carbohydrates, NAFLD, NASH, Physical activity

The function of biological membranes is controlled by the interaction of the fluid lipid bilayer with various proteins, some of which induce or react to curvature. These proteins can preferentially bind or diffuse towards curved regions of the membrane, induce or stabilize membrane curvature and sequester membrane area into protein-rich curved domains. The resulting tight interplay between mechanics and chemistry is thought to control organelle morphogenesis and dynamics, including traffic, membrane mechanotransduction, or membrane area regulation and tension buffering. Despite all these processes are fundamentally dynamical, previous work has largely focused on equilibrium and a self-consistent theoretical treatment of the dynamics of curvature sensing and generation has been lacking. Here, we develop a general theoretical and computational framework based on a nonlinear Onsager's formalism of irreversible thermodynamics for the dynamics of curved proteins and membranes. We develop variants of the model, one of which accounts for membrane curving by asymmetric crowding of bulky off-membrane protein domains. As illustrated by a selection of test cases, the resulting governing equations and numerical simulations provide a foundation to understand the dynamics of curvature sensing, curvature generation, and more generally membrane curvature mechano-chemistry.

JTD Keywords: Curvature generation, Curvature sensing, Lipid bilayers, Membrane proteins

Several studies have indicated that certain misfolded amyloids composed of tau, β-amyloid or α-synuclein can be transferred from cell to cell, suggesting the contribution of mechanisms reminiscent of those by which infective prions spread through the brain. This process of a ‘prion-like’ spreading between cells is also relevant as a novel putative therapeutic target that could block the spreading of proteinaceous aggregates throughout the brain which may underlie the progressive nature of neurodegenerative diseases. The relevance of β-amyloid oligomers and cellular prion protein (PrPC) binding has been a focus of interest in Alzheimer’s disease (AD). At the molecular level, β-amyloid/PrPC interaction takes place in two differently charged clusters of PrPC. In addition to β-amyloid, participation of PrPC in α-synuclein binding and brain spreading also appears to be relevant in α-synucleopathies. This review summarizes current knowledge about PrPC as a putative receptor for amyloid proteins and the physiological consequences of these interactions..

JTD Keywords: Cellular prion protein, Amyloid, Proteinaceous species, ‘prion-like’ spreading, Spreading, Neurodegeneration

How many copies of a protein can be made before it becomes toxic to the cell?

JTD Keywords: Protein burden, Overexpression, Glycolysis

Extracellular matrix (ECM) proteins are key mediators of cell/material interactions. The surface density and conformation of these proteins adsorbed on the material surface influence cell adhesion and the cellular response. We have previously shown that subtle variations in surface chemistry lead to drastic changes in the conformation of adsorbed fibronectin (FN). On poly(ethyl acrylate) (PEA), FN unfolds and displays domains for cell adhesion and FN-FN interaction, whereas on poly(methyl acrylate) (PMA) – with only one methyl group less – FN remains globular as it is in solution. The effect of the strength of the protein/material interaction in cell response, and its relation to protein density and conformation, has received limited attention so far. In this work, we used FN-functionalized AFM cantilevers to evaluate, via force spectroscopy, the strength of interaction between fibronectin and the underlying polymer which controls FN conformation (PEA and PMA). We found that the strength of FN/PEA interaction is significantly higher than FN/PMA, which limits the mobility of FN layer on PEA, reduces the ability of cells to mechanically reorganize FN and then leads to enhanced proteolysis and degradation of the surrounding matrix with compromised cell viability. By contrast, both PEA and PMA support cell adhesion when FN density is increased and also in the presence of serum or other serum proteins, including vitronectin (VN) and bovine serum albumin (BSA), which provide a higher degree of mobility to the matrix. Statement of Significance: The identification of parameters influencing cell response is of paramount importance for the design of biomaterials that will act as synthetic scaffolds for cells to anchor, grow and, eventually, become specialised tissues. Cells interact with materials through an intermediate layer of proteins adsorbed on the material surface. It is known that the density and conformation of these proteins determine cell behaviour. Here we show that the strength of protein/material interactions, which has received very limited attention so far, is key to understand the cellular response to biomaterials. Very strong protein/material interactions reduce the ability of cells to mechanically reorganize proteins at the material interface which results in enhanced matrix degradation, leading ultimately to compromised cell viability.

JTD Keywords: Fibronectin adsorption, Fibronectin remodeling, Protein mobility, Protein-material interaction strength

Aim: To develop a nanofiber (NF)-based biomimetic coating on titanium (Ti) that mimics the complex spatiotemporal organization of the extracellular matrix (ECM). Materials & methods: Recombinant cell attachment site (CAS) of fibronectin type III8-10 domain was co-electrospun with polylactic acid (PLA) and covalently bound on polished Ti discs. Osteoblast-like SaOS-2 cells were used to evaluate their complex bioactivity. Results: A significant increase of cell spreading was found on CAS/PLA hybrid NFs, followed by control pure PLA NFs and bare Ti discs. Cell proliferation showed similar trend being about twice higher on CAS/PLA NFs. The significantly increased ALP activity at day 21 indicated an enhanced differentiation of SaOS-2 cells. Conclusion: Coating of Ti implants with hybrid CAS/PLA NFs may improve significantly their osseointegration potential.

JTD Keywords: Electrospinning, Fibronectin, Hybrid nanofibers, Osseointegration, PLA, Recombinant protein

Gerstmann-Sträussler-Scheinker (GSS) syndrome is a fatal autosomal dominant neurodegenerative prionopathy clinically characterized by ataxia, spastic paraparesis, extrapyramidal signs and dementia. In some GSS familiar cases carrying point mutations in the PRNP gene, patients also showed comorbid tauopathy leading to mixed pathologies. In this study we developed an induced pluripotent stem (iPS) cell model derived from fibroblasts of a GSS patient harboring the Y218N PRNP mutation, as well as an age-matched healthy control. This particular PRNP mutation is unique with very few described cases. One of the cases presented neurofibrillary degeneration with relevant Tau hyperphosphorylation. Y218N iPS-derived cultures showed relevant astrogliosis, increased phospho-Tau, altered microtubule-associated transport and cell death. However, they failed to generate proteinase K-resistant prion. In this study we set out to test, for the first time, whether iPS cell-derived neurons could be used to investigate the appearance of disease-related phenotypes (i.e, tauopathy) identified in the GSS patient.

JTD Keywords: Cellular prion protein, Gerstmann-Sträussler-Scheinker, Induced pluripotent stem cells, Tau

Prions are a singular subset of proteins able to switch between a soluble conformation and a self-perpetuating amyloid state. Traditionally associated with neurodegenerative diseases, increasing evidence indicates that organisms exploit prion-like mechanisms for beneficial purposes. The ability to transit between conformations is encoded in the so-called prion domains, long disordered regions usually enriched in glutamine/asparagines residues. Interestingly, Plasmodium falciparum, the parasite that causes the most virulent form of malaria, is exceptionally rich in proteins bearing long Q/N-rich sequence stretches, accounting for roughly 30% of the proteome. This biased composition suggests that these protein regions might correspond to prion-like domains (PrLDs) and potentially form amyloid assemblies. To investigate this possibility, we performed a stringent computational survey for Q/N-rich PrLDs on P. falciparum. Our data indicate that ~10% of P. falciparum protein sequences have prionic signatures, and that this subproteome is enriched in regulatory proteins, such as transcription factors and RNA-binding proteins. Furthermore, we experimentally demonstrate for several of the identified PrLDs that, despite their disordered nature, they contain inner short sequences able to spontaneously self-assemble into amyloid-like structures. Although the ability of these sequences to nucleate the conformational conversion of the respective full-length proteins should still be demonstrated, our analysis suggests that, as previously described for other organisms, prion-like proteins might also play a functional role in P. falciparum.

JTD Keywords: Plasmodium, Protein aggregation, Amyloid, Prion, Q-N-rich sequences, Protein Disorder

Casein micelles are ~200 nm electronegative particles that constitute 80 wt% of the milk proteins. During synthesis in the lactating mammary cells, caseins are thought to interact in the form of ~20 nm assemblies, directly with the biological membranes of the endoplasmic reticulum and/or the Golgi apparatus. However, conditions that drive this interaction are not yet known. Atomic force microscopy imaging and force spectroscopy were used to directly observe the adsorption of casein particles on supported phospholipid bilayers with controlled compositions to vary their phase state and surface charge density, as verified by X-ray diffraction and zetametry. At pH 6.7, the casein particles adsorbed onto bilayer phases with zwitterionic and liquid-disordered phospholipid molecules, but not on phases with anionic or ordered phospholipids. Furthermore, the presence of adsorbed caseins altered the stability of the yet exposed bilayer. Considering their respective compositions and symmetry/asymmetry, these results cast light on the possible interactions of casein assemblies with the organelles’ membranes of the lactating mammary cells.

JTD Keywords: Casein proteins, Phospholipid membrane, Supported lipid bilayer, Atomic force microscopy

Within the research in Molecular Biology, one important field along the years has been the analyses on how prokaryotes regulate the expression of their genes and what the consequences of these activities are. Prokaryotes have attracted the interests of researchers not only because the processes taking place in their world are important to cells, but also because many of the effects often can be readily measured, both at the single cell level and in large populations. Contributing to the interest of the present topic is the fact that modulation of gene activity involves the sensing of intra- and inter-cellular conditions, DNA binding and DNA dynamics, and interaction with the replication/transcription machinery of the cell. All of these processes are fundamental to the operation of a biological entity and they condition its lifestyle. Further, the discoveries achieved in the bacterial world have been of ample use in eukaryotes. In addition to the fundamental interest of understanding modulation of prokaryotic lifestyle by DNA-binding proteins, there is an added interest from the healthcare point of view. As it is well-known the antibiotic-resistance strains of pathogenic bacteria are a major world problem, so that there is an urgent need of innovative approaches to tackle it. Human and animal infectious diseases impose staggering costs worldwide in terms of loss of human life and livestock, diminished productivity, and the heavy economic burden of disease. The global dimension of international trade, personal travel, and population migration expands at an ever-accelerating rate. This increasing mobility results in broader and quicker dissemination of bacterial pathogens and in rapid spread of antibiotic resistance. The majority of the newly acquired resistances are horizontally spread among bacteria of the same or different species by processes of lateral (horizontal) gene transfer, so that discovery of new antibiotics is not the definitive solution to fighting infectious diseases. There is an absolute need of finding novel alternatives to the “classical” approach to treat infections by bacterial pathogens, and these new ways must include the exploration and introduction of novel antibacterials, the development of alternative strategies, and the finding of novel bacterial targets. However, all these approaches will result in a stalemate if we, researchers, are not able to achieve a better understanding of the mechanistic processes underlying bacterial gene expression. It is, then, imperative to continue gaining insight into the basic mechanisms by which bacterial cells regulate the expression of their genes. That is why our Research Topic hosted by Frontiers in Molecular Biosciences was timely, and the output of it offers novel and up-to-date points of view to the “simple” bacterial world.

JTD Keywords: DNA-protein interactions, Gene regulation in Prokaryotes, Replication control, Regulation of Bacterial Gene Expression, Global Regulatory Networks

Electron transfer in proteins is essential in crucial biological processes. Although the fundamental aspects of biological electron transfer are well characterized, currently there are no experimental tools to determine the atomic-scale electronic pathways in redox proteins, and thus to fully understand their outstanding efficiency and environmental adaptability. This knowledge is also required to design and optimize biomolecular electronic devices. In order to measure the local conductance of an electrode surface immersed in an electrolyte, this study builds upon the current–potential spectroscopic capacity of electrochemical scanning tunneling microscopy, by adding an alternating current modulation technique. With this setup, spatially resolved, differential electrochemical conductance images under bipotentiostatic control are recorded. Differential electrochemical conductance imaging allows visualizing the reversible oxidation of an iron electrode in borate buffer and individual azurin proteins immobilized on atomically flat gold surfaces. In particular, this method reveals submolecular regions with high conductance within the protein. The direct observation of nanoscale conduction pathways in redox proteins and complexes enables important advances in biochemistry and bionanotechnology.

JTD Keywords: Differential electrochemical conductance, ECSTM, Electron transport pathway, Iron passivation, Redox metalloproteins

The adsorption of serum proteins, leading to the formation of a biomolecular corona, is a key determinant of the biological identity of nanoparticles in vivo. Therefore, gaining knowledge on the formation, composition, and temporal evolution of the corona is of utmost importance for the development of nanoparticle-based therapies. Here, it is shown that the use of super-resolution optical microscopy enables the imaging of the protein corona on mesoporous silica nanoparticles with single protein sensitivity. Particle-by-particle quantification reveals a significant heterogeneity in protein absorption under native conditions. Moreover, the diversity of the corona evolves over time depending on the surface chemistry and degradability of the particles. This paper investigates the consequences of protein adsorption for specific cell targeting by antibody-functionalized nanoparticles providing a detailed understanding of corona-activity relations. The methodology is widely applicable to a variety of nanostructures and complements the existing ensemble approaches for protein corona study.

JTD Keywords: Heterogeneity, Mesoporous silica nanoparticles, Protein corona, Super-resolution imaging, Targeting

The expression of subunits of mitochondrial respiratory complexes and components of the protein synthesis machinery from the nucleolus to the ribosome was analyzed in the mediodorsal thalamus in seven cases of Fatal Familial Insomnia (FFI) compared with age-matched controls. NDUFB8 (complex I subunit), SDHB (complex II subunit), UQCRC2 (complex III subunit), COX2 (complex IV subunit) and ATP50 (complex V subunit) expression levels, as revealed by western blotting, were reduced in FFI. Voltage-dependent anion channel (VDAC) and ATP5H were also reduced due to the marked depopulation of neurons. In contrast, a marked increase in superoxide dismutase 2 (SOD2) was found in reactive astrocytes thus suggesting that astrocytes are key factors in oxidative stress responses. The histone-binding chaperones nucleolin and nucleoplasmin 3, and histone H3 di-methylated K9 were markedly reduced together with a decrease in the expression of protein transcription elongation factor eEF1A. These findings show severe impairment in the expression of crucial components of mitochondrial function and protein synthesis in parallel with neuron loss in mediodorsal thalamus at terminal stages of FFI. Therapeutic measures must be taken long before the appearance of clinical symptoms to prevent the devastating effects of FFI.

JTD Keywords: Fatal familial insomnia, Mitochondria, Protein synthesis, Mitochondrial respiratory chain, Nucleolus, Ribosome

Reelin is an extracellular glycoprotein involved in key cellular processes in developing and adult nervous system, including regulation of neuronal migration, synapse formation, and plasticity. Most of these roles are mediated by the intracellular phosphorylation of disabled-1 (Dab1), an intracellular adaptor molecule, in turn mediated by binding Reelin to its receptors. Altered expression and glycosylation patterns of Reelin in cerebrospinal and cortical extracts have been reported in Alzheimer’s disease. However, putative changes in Reelin are not described in natural prionopathies or experimental models of prion infection or toxicity. With this is mind, in the present study, we determined that Reelin protein and mRNA levels increased in CJD human samples and in mouse models of human prion disease in contrast to murine models of prion infection. However, changes in Reelin expression appeared only at late terminal stages of the disease, which prevent their use as an efficient diagnostic biomarker. In addition, increased Reelin in CJD and in in vitro models does not correlate with Dab1 phosphorylation, indicating failure in its intracellular signaling. Overall, these findings widen our understanding of the putative changes of Reelin in neurodegeneration.

JTD Keywords: Reelin, Creutzfeldt-Jakob disease, Dab-1, Cellular prion protein

Objectives: The goal of this study was to assess mitochondrial function, energy, and purine metabolism, protein synthesis machinery from the nucleolus to the ribosome, inflammation, and expression of newly identified ectopic olfactory receptors (ORs) and taste receptors (TASRs) in the frontal cortex of typical cases of dementia with Lewy bodies (DLB) and cases with rapid clinical course (rpDLB: 2 years or less) compared with middle-aged non-affected individuals, in order to learn about the biochemical abnormalities underlying Lewy body pathology. Methods: Real-time quantitative PCR, mitochondrial enzymatic assays, and analysis of β-amyloid, tau, and synuclein species were used. Results: The main alterations in DLB and rpDLB, which are more marked in the rapidly progressive forms, include (i) deregulated expression of several mRNAs and proteins of mitochondrial subunits, and reduced activity of complexes I, II, III, and IV of the mitochondrial respiratory chain; (ii) reduced expression of selected molecules involved in energy metabolism and increased expression of enzymes involved in purine metabolism; (iii) abnormal expression of nucleolar proteins, rRNA18S, genes encoding ribosomal proteins, and initiation factors of the transcription at the ribosome; (iv) discrete inflammation; and (v) marked deregulation of brain ORs and TASRs, respectively. Severe mitochondrial dysfunction involving activity of four complexes, minimal inflammatory responses, and dramatic altered expression of ORs and TASRs discriminate DLB from Alzheimer’s disease. Altered solubility and aggregation of α-synuclein, increased β-amyloid bound to membranes, and absence of soluble tau oligomers are common in DLB and rpDLB. Low levels of soluble β-amyloid are found in DLB. However, increased soluble β-amyloid 1–40 and β-amyloid 1–42, and increased TNFα mRNA and protein expression, distinguish rpDLB. Conclusion: Molecular alterations in frontal cortex in DLB involve key biochemical pathways such as mitochondria and energy metabolism, protein synthesis, purine metabolism, among others and are accompanied by discrete innate inflammatory response.

JTD Keywords: Dementia with Lewy bodies, Alzheimer’s disease, α-synuclein, Mitochondria, Protein synthesis, Inflammation, β-amyloid, Olfactory receptors

exThe CFDP1 proteins have been linked to craniofacial development and osteogenesis in vertebrates, though specific human syndromes have not yet been identified. Alterations of craniofacial development represent the main cause of infant disability and mortality in humans. For this reason, it is crucial to understand the cellular functions and mechanism of action of the CFDP1 protein in model vertebrate organisms. Using a combination of genomic, molecular and cell biology approaches, we have performed a functional analysis of the cfdp1 gene and its encoded protein, zCFDP1, in the zebrafish model system. We found that zCFDP1 is present in the zygote, is rapidly produced after MTZ transition and is highly abundant in the head structures. Depletion of zCFDP1, induced by an ATG-blocking morpholino, produces considerable defects in craniofacial structures and bone mineralization. Together, our results show that zCFDP1 is an essential protein required for proper development and provide the first experimental evidence showing that in vertebrates it actively participates to the morphogenesis of craniofacial territories.

JTD Keywords: Craniofacial development, BCNT protein family, Zebrafish, Morpholino

Global regulators play an essential role in the adaptation of bacterial cells to specific niches. Bacterial pathogens thriving in the tissues and organs of their eukaryotic hosts are a well-studied example. Some of the proteins that recognize local DNA structures rather than specific nucleotide sequences act as global modulators in many bacteria, both Gram-negative and -positive. To this class of regulators belong the H-NS-like proteins, mainly identified in γ-Proteobacteria, and the MgaSpn-like proteins identified in Firmicutes. H-NS and MgaSpn from Escherichia coli and Streptococcus pneumoniae, respectively, neither have sequence similarity nor share structural domains. Nevertheless, they display common features in their interaction with DNA, namely: (i) they bind to DNA in a non-sequence-specific manner, (ii) they have a preference for intrinsically curved DNA regions, and (iii) they are able to form multimeric complexes on linear DNA. Using DNA fragments from the hemolysin operon regulatory region of the E. coli plasmid pHly152, we show in this work that MgaSpn is able to recognize particular regions on extended H-NS binding sites. Such regions are either located at or flanked by regions of potential bendability. Moreover, we show that the regulatory region of the pneumococcal P1623B promoter, which is recognized by MgaSpn, contains DNA motifs that are recognized by H-NS. These motifs are adjacent to regions of potential bendability. Our results suggest that both regulatory proteins recognize similar structural characteristics of DNA.

JTD Keywords: Global transcriptional regulators, Nucleoid-associated proteins, Mga/AtxA family, Protein-DNA interactions, DNA bendability

Protein-based nanofibrils are emerging as a promising class of materials that provide unique properties for applications such as biomedical and food engineering. Here, we use atomic force microscopy and stochastic optical reconstruction microscopy imaging to elucidate the growth dynamics, exchange kinetics, and polymerization mechanism for fibrils composed of a de novo designed recombinant triblock protein polymer. This macromolecule features a silk-inspired self-assembling central block composed of GAGAGAGH repeats, which are known to fold into a β roll with turns at each histidine and, once folded, to stack, forming a long, ribbon-like structure. We find several properties that allow the growth of patterned protein nanofibrils: the self-assembly takes place on only one side of the growing fibrils by the essentially irreversible addition of protein polymer subunits, and these fibril ends remain reactive indefinitely in the absence of monomer ("living ends"). Exploiting these characteristics, we can grow stable diblock protein nanofibrils by the sequential addition of differently labeled proteins. We establish control over the block length ratio by simply varying monomer feed conditions. Our results demonstrate the use of engineered protein polymers in creating precisely patterned protein nanofibrils and open perspectives for the hierarchical self-assembly of functional biomaterials.

JTD Keywords: Nanofibrils, Protein polymers, Self-assembly, STORM microscopy

The biological functions of the cellular prion protein remain poorly understood. In fact, numerous studies have aimed to determine specific functions for the different protein domains. Studies of cellular prion protein (PrPC) domains through in vivo expression of molecules carrying internal deletions in a mouse Prnp null background have provided helpful data on the implication of the protein in signalling cascades in affected neurons. Nevertheless, understanding of the mechanisms underlying the neurotoxicity induced by these PrPC deleted forms is far from complete. To better define the neurotoxic or neuroprotective potential of PrPC N-terminal domains, and to overcome the heterogeneity of results due to the lack of a standardized model, we used neuroblastoma cells to analyse the effects of overexpressing PrPC deleted forms. Results indicate that PrPC N-terminal deleted forms were properly processed through the secretory pathway. However, PrPΔF35 and PrPΔCD mutants led to death by different mechanisms sharing loss of alpha-cleavage and activation of caspase-3. Our data suggest that both gain-of-function and loss-of-function pathogenic mechanisms may be associated with N-terminal domains and may therefore contribute to neurotoxicity in prion disease. Dissecting the molecular response induced by PrPΔF35 may be the key to unravelling the physiological and pathological functions of the prion protein.

JTD Keywords: Cellular prion protein, Neurotoxicity, Truncated prion protein

IncHI plasmids account for multiple antimicrobial resistance in Salmonella and other enterobacterial genera. These plasmids are generally very stable in their bacterial hosts. R27 is the archetype of IncHI1 plasmids. A high percentage of the R27-encoded open reading frames (ORFs) (66.7%) do not show similarity to any known ORFs. We performed a deletion analysis of all non-essential R27 DNA sequences to search for hitherto non-identified plasmid functions that might be required for plasmid stability. We report the identification of a short DNA sequence (incC) that is essential for R27 stability. That region contains several repeats (incC repeats), belongs to one of the three-plasmid replicons (R27 FIA-like) and is targeted by the R27 E protein. Deletion of the incC sequence drastically reduces R27 stability both in Escherichia coli and in Salmonella, the effect being more pronounced in this latter species. Interfering with incC-E protein interaction must lead to a reduced IncHI1 plasmid stability, and may represent a new approach to combat antimicrobial resistance.

JTD Keywords: Antimicrobial resistance, E protein, IncC, IncHI1 plasmids, Plasmid R27, Plasmid stability

Cell membrane proteins are involved in a variety of biochemical pathways and therefore constitute important targets for therapy and development of new drugs. Bioanalytical platforms and binding assays using these membrane protein receptors for drug screening or diagnostic require the construction of well-characterized liposome and lipid bilayer arrays that act as support to prevent protein denaturation during biochip processing. Quantification of the protein receptors in the lipid membrane arrays is a key issue in order to produce reproducible and well-characterized chips. Herein, we report a novel immunochemical analytical approach for the quantification of membrane proteins (i.e., G-protein-coupled receptor, GPCR) in nanovesicles (NVs). The procedure allows direct determination of tagged receptors (i.e., c-myc tag) without any previous protein purification or extraction steps. The immunochemical method is based on a microplate ELISA format and quantifies this tag on proteins embedded in NVs with detectability in the picomolar range, using protein bioconjugates as reference standards. The applicability of the method is demonstrated through the quantification of the c-myc-olfactory receptor (OR, c-myc-OR1740) in the cell membrane NVs. The reported method opens the possibility to develop well-characterized drug-screening platforms based on G-coupled proteins embedded on membranes.

JTD Keywords: Bioelectronic nose, Competitive ELISA, G-protein-coupled receptors quantification, Natural vesicles, Olfactory receptors, Transmembrane proteins

Neuron loss, synaptic decline, and spongiform change are the hallmarks of sporadic Creutzfeldt–Jakob disease (sCJD), and may be related to deficiencies in mitochondria, energy metabolism, and protein synthesis. To investigate these relationships, we determined the expression levels of genes encoding subunits of the 5 protein complexes of the electron transport chain, proteins involved in energy metabolism, nucleolar and ribosomal proteins, and enzymes of purine metabolism in frontal cortex samples from 15 cases of sCJD MM1 and age-matched controls. We also assessed the protein expression levels of subunits of the respiratory chain, initiation and elongation translation factors of protein synthesis, and localization of selected mitochondrial components. We identified marked, generalized alterations of mRNA and protein expression of most subunits of all 5 mitochondrial respiratory chain complexes in sCJD cases. Expression of molecules involved in protein synthesis and purine metabolism were also altered in sCJD. These findings point to altered mRNA and protein expression of components of mitochondria, protein synthesis machinery, and purine metabolism as components of the pathogenesis of CJD.

JTD Keywords: Creutzfeldt–Jakob disease, Electron transport chain, Mitochondria, Oxidative phosphorylation, Protein synthesis, Purine.

Metabotropic glutamate receptors (mGluRs) are important drug targets because of their involvement in several neurological diseases. Among mGluRs, mGlu5 is a particularly high-profile target because its positive or negative allosteric modulation can potentially treat schizophrenia or anxiety and chronic pain, respectively. Here, we computationally and experimentally probe the functional binding of a novel photoswitchable mGlu5 NAM, termed alloswitch-1, which loses its NAM functionality under violet light. We show alloswitch-1 binds deep in the allosteric pocket in a similar fashion to mavoglurant, the co-crystallized NAM in the mGlu5 transmembrane domain crystal structure. Alloswitch-1, like NAM 2-Methyl-6-(phenylethynyl)pyridine (MPEP), is significantly affected by P655M mutation deep in the allosteric pocket, eradicating its functionality. In MD simulations, we show alloswitch-1 and MPEP stabilize the co-crystallized water molecule located at the bottom of the allosteric site that is seemingly characteristic of the inactive receptor state. Furthermore, both NAMs form H-bonds with S809 on helix 7, which may constitute an important stabilizing interaction for NAM-induced mGlu5 inactivation. Alloswitch-1, through isomerization of its amide group from trans to cis is able to form an additional interaction with N747 on helix 5. This may be an important interaction for amide-containing mGlu5 NAMs, helping to stabilize their binding in a potentially unusual cis-amide state. Simulated conformational switching of alloswitch-1 in silico suggests photoisomerization of its azo group from trans to cis may be possible within the allosteric pocket. However, photoexcited alloswitch-1 binds in an unstable fashion, breaking H-bonds with the protein and destabilizing the co-crystallized water molecule. This suggests photoswitching may have destabilizing effects on mGlu5 binding and functionality.

JTD Keywords: Allosteric modulation, Docking, Metabotropic glutamate receptor, Molecular dynamics, Mutation, Protein structure, Transmembrane domain

The main therapeutic and prophylactic tools against malaria have been locked for more than a century in the classical approaches of using drugs targeting metabolic processes of the causing agent, the protist Plasmodium spp., and of designing vaccines against chosen antigens found on the parasite’s surface. Given the extraordinary resources exhibited by Plasmodium to escape these traditional strategies, which have not been able to free humankind from the scourge of malaria despite much effort invested in them, new concepts have to be explored in order to advance toward eradication of the disease. In this context, amyloid-forming proteins and peptides found in the proteome of the pathogen should perhaps cease being regarded as mere anomalous molecules. Their likely functionality in the pathophysiology of Plasmodium calls for attention being paid to them as a possible Achilles’ heel of malaria. Here we will give an overview of Plasmodium-encoded amyloid-forming polypeptides as potential therapeutic targets and toxic elements, particularly in relation to cerebral malaria and the blood–brain barrier function. We will also discuss the recent finding that the genome of the parasite contains an astonishingly high proportion of prionogenic domains.

JTD Keywords: Amyloids, Intrinsically unstructured proteins, Malaria, Prions

Pulmonary delivery of drugs for both local and systemic action has gained new attention over the last decades. In this work, different amphiphilic polymers (Soluplus®, Pluronic® F68, Pluronic® F108 and Pluronic® F127) were used to produce lyophilized formulations for inhalation of insulin. Development of stimuli-responsive, namely glucose-sensitive, formulations was also attempted with the addition of phenylboronic acid (PBA). Despite influencing the in vitro release of insulin from micelles, PBA did not confer glucose-sensitive properties to formulations. Lyophilized powders with aerodynamic diameter (<. 6. μm) compatible with good deposition in the lungs did not present significant in vitro toxicity for respiratory cell lines. Additionally, some formulations, in particular Pluronic® F127-based formulations, enhanced the permeation of insulin through pulmonary epithelial models and underwent minimal internalization by macrophages in vitro. Overall, formulations based on polymeric micelles presenting promising characteristics were developed for the delivery of insulin by inhalation. From the Clinical Editor: The ability to deliver other systemic drugs via inhalation has received renewed interests in the clinical setting. This is especially true for drugs which usually require injections for delivery, like insulin. In this article, the authors investigated their previously developed amphiphilic polymers for inhalation of insulin in an in vitro model. The results should provide basis for future in vivo studies.

JTD Keywords: Cytotoxicity, Inhalation, Permeability, Phagocytosis, Polymeric micelles, Protein delivery

Alzheimer's disease (AD) is characterized by the presence of amyloid plaques mainly consisting of hydrophobic β-amyloid peptide (Aβ) aggregates and neurofibrillary tangles (NFTs) composed principally of hyperphosphorylated tau. Aβ oligomers have been described as the earliest effectors to negatively affect synaptic structure and plasticity in the affected brains, and cellular prion protein (PrPC) has been proposed as receptor for these oligomers. The most widely accepted theory holds that the toxic effects of Aβ are upstream of change in tau, a neuronal microtubule-associated protein that promotes the polymerization and stabilization of microtubules. However, tau is considered decisive for the progression of neurodegeneration, and, indeed, tau pathology correlates well with clinical symptoms such as dementia. Different pathways can lead to abnormal phosphorylation, and, as a consequence, tau aggregates into paired helical filaments (PHF) and later on into NFTs. Reported data suggest a regulatory tendency of PrPC expression in the development of AD, and a putative relationship between PrPC and tau processing is emerging. However, the role of tau/PrPC interaction in AD is poorly understood. In this study, we show increased susceptibility to Aβ-derived diffusible ligands (ADDLs) in neuronal primary cultures from PrPC knockout mice, compared to wild-type, which correlates with increased tau expression. Moreover, we found increased PrPC expression that paralleled with tau at early ages in an AD murine model and in early Braak stages of AD in affected individuals. Taken together, these results suggest a protective role for PrPC in AD by downregulating tau expression, and they point to this protein as being crucial in the molecular events that lead to neurodegeneration in AD.

JTD Keywords: Aβ oligomers, Alzheimer's disease, Cellular prion protein, Microtubule-associated protein tau

Aims Creutzfeldt-Jakob disease (CJD) is a rapid progressive neurological disease leading to dementia and death. Prion biomarkers are altered in the cerebrospinal fluid (CSF) of CJD patients, but the pathogenic mechanisms underlying these alterations are still unknown. The present study examined prion biomarker levels in the brain and CSF of sporadic CJD (sCJD) cases and their correlation with neuropathological lesion profiles. Methods The expression levels of 14-3-3, Tau, phospho-Tau and α-synuclein were measured in the CSF and brain of sCJD cases in a subtype- and region-specific manner. In addition, the activity of prion biomarker kinases, the expression levels of CJD hallmarks and the most frequent neuropathological sCJD findings were analysed. Results Prion biomarkers levels were increased in the CSF of sCJD patients; however, correlations between mRNA, total protein and their phosphorylated forms in brain were different. The observed downregulation of the main Tau kinase, GSK3, in sCJD brain samples may help to explain the differential phospho-Tau/Tau ratios between sCJD and other dementias in the CSF. Importantly, CSF biomarkers levels do not necessarily correlate with sCJD neuropathological findings. Interpretation Present findings indicate that prion biomarkers levels in sCJD tissues and their release into the CSF are differentially regulated following specific modulated responses, and suggest a functional role for these proteins in sCJD pathogenesis.

JTD Keywords: Creutzfeldt-Jakob disease, Prion Protein, Cerebrospinal fluid, Prion Biomarkers, disease subtype, Glycogen synthase kinase 3

The electric polarizability of DNA, represented by the dielectric constant, is a key intrinsic property that modulates DNA interaction with effector proteins. Surprisingly, it has so far remained unknown owing to the lack of experimental tools able to access it. Here, we experimentally resolved it by detecting the ultraweak polarization forces of DNA inside single T7 bacteriophages particles using electrostatic force microscopy. In contrast to the common assumption of low-polarizable behavior like proteins (εr ~ 2–4), we found that the DNA dielectric constant is ~ 8, considerably higher than the value of ~ 3 found for capsid proteins. State-of-the-art molecular dynamic simulations confirm the experimental findings, which result in sensibly decreased DNA interaction free energy than normally predicted by Poisson–Boltzmann methods. Our findings reveal a property at the basis of DNA structure and functions that is needed for realistic theoretical descriptions, and illustrate the synergetic power of scanning probe microscopy and theoretical computation techniques.

JTD Keywords: Atomic force microscopy, Atomistic simulations, DNA packaging, DNA-ligand binding, Poisson-Boltzmann equation, capsid protein, DNA, double stranded DNA, amino acid composition, article, atomic force microscopy, bacteriophage, bacteriophage T7, dielectric constant, dipole, DNA binding, DNA packaging, DNA structure, electron microscopy, ligand binding, nonhuman, polarization, priority journal, protein analysis, protein DNA interaction, scanning probe microscopy, static electricity, virion, virus capsid, virus particle, atomic force microscopy, atomistic simulations, DNA packaging, DNA-ligand binding, Poisson-Boltzmann equation, Bacteriophage T7, Capsid, Cations, Dielectric Spectroscopy, DNA, DNA, Viral, DNA-Binding Proteins, Electrochemical Techniques, Ligands, Microscopy, Atomic Force, Models, Chemical, Nuclear Proteins

Switching events in the current flowing through individual redox proteins, (azurin) spontaneously wired between two electrodes, are studied using an electrochemical scanning tunneling microscope (ECSTM). These switching events in the current–time trace are characterized using conductance histograms, and reflect the intrinsic redox thermodynamic dispersion in the azurin population. This conductance switching may pose limitations to miniaturizing redox protein-based devices.

JTD Keywords: Bioelectronics, Protein transistors, Molecular junctions, Switches, STM

Dip-pen nanolithography and microcontact printing were used to fabricate mesopatterned substrates for cell differentiation experiments. A biotin-thiol was patterned on gold substrates and subsequently functionalised with streptavidin and biotinylated bone morphogenetic protein-2 (BMP-2). The feasibility of mesopatterned substrates containing immobilised BMP-2 was proven by obtaining similar differentiation outcomes compared to the growth factor in solution. Therefore, these substrates might be suitable for replacing conventional experiments with BMP-2 in solution.

JTD Keywords: Bone morphogenetic protein-2, C2C12 cells, Dip-pen nanolithography, Micro contact printing

Control of membrane traffic: Photoswitchable inhibitors of protein-protein interactions were applied to photoregulate clathrin-mediated endocytosis (CME) in living cells. Traffic light (TL) peptides acting as "stop" and "go" signals for membrane traffic can be used to dissect the role of CME in receptor internalization and in cell growth, division, and differentiation.

JTD Keywords: Clathrin-mediated endocytosis, Optopharmacology, Peptides, Photoswitches, Protein-protein interactions

The prion protein (PrP) plays a key role in prion disease pathogenesis. Although the misfolded and pathologic variant of this protein (PrPSC) has been studied in depth, the physiological role of PrPC remains elusive and controversial. PrPC is a cell-surface glycoprotein involved in multiple cellular functions at the plasma membrane, where it interacts with a myriad of partners and regulates several intracellular signal transduction cascades. However, little is known about the gene expression changes modulated by PrPC in animals and in cellular models. In this article, we present PrPC-dependent gene expression signature in N2a cells and its implication in the most overrepresented functions: cell cycle, cell growth and proliferation, and maintenance of cell shape. PrPC over-expression enhances cell proliferation and cell cycle re-entrance after serum stimulation, while PrPC silencing slows down cell cycle progression. In addition, MAP kinase and protein kinase B (AKT) pathway activation are under the regulation of PrPC in asynchronous cells and following mitogenic stimulation. These effects are due in part to the modulation of epidermal growth factor receptor (EGFR) by PrPC in the plasma membrane, where the two proteins interact in a multimeric complex. We also describe how PrPC over-expression modulates filopodia formation by Rho GTPase regulation mainly in an AKT-Cdc42-N-WASP-dependent pathway.

JTD Keywords: Cell signaling, Cellular prion protein, Filopodia, Gene expression, Microarray, Proliferation

H-NS and Hha belong to the nucleoid-associated family of proteins and modulate gene expression in response to environmental stimuli. Genes coding for these proteins can be either chromosomally or plasmid-encoded. In this work, we analyse the regulatory role of the Hha protein encoded in the virulence plasmid of the enterohemorrhagic Escherichia coli O157:H7 (HhapO157). This plasmid is present in all clinical isolates of E. coli O157:H7 and contributes to virulence. Both, HhapO157 and E. coli O157:H7-chromosomal Hha (Hhachr) exhibit a significant degree of similarity. The hha gene from plasmid pO157 is transcribed from its own putative promoter and is overexpressed in a chromosomal hha mutant. As its chromosomal counterpart, HhapO157 is able to interact with H-NS. Remarkably, HhapO157 targets only a subset of the genes modulated by Hhachr. This has been evidenced by both assaying the ability of HhapO157 to complement expression of a specific operon (i.e., the haemolysin operon) and by comparing the global transcriptome of the wt strain and its hhap, hhac and hhapc mutant derivatives. HhapO157 and Hhachr share some common regulatory features, however they also display specific targeting of some genes and even a different modulatory role in some others.

JTD Keywords: E. coli O157:H7, Hha, H-NS, Plasmid, pO157, Nucleoid-associated proteins

Molecular machines and nanomotors are sophisticated biological assemblies that convert potential energy stored either in transmembrane ion gradients or in ATP into kinetic energy. Studying these highly dynamic biological devices by X-ray crystallography is challenging, as they are difficult to produce, purify, and crystallize. Phage display technology allows us to put a handle on these molecules in the form of highly specific antibody fragments that can also stabilize conformations and allow versatile labelling for electron microscopy, immunohistochemistry, and biophysics experiments. Here, we describe a widely applicable protocol for selecting high-affinity monoclonal antibody fragments against a complex molecular machine, the A-type ATPase from T. thermophilus that allows fast and simple purification of this transmembrane rotary motor from its wild-type source. The approach can be readily extended to other integral membrane proteins and protein complexes as well as to soluble molecular machines and nanomotors.

JTD Keywords: ATP synthase, Crystallization, Domain antibodies, Electron microscopy, Labelling, Membrane proteins, Monoclonal antibody fragments, Phage display, Protein purification, X-ray crystallography

Calcium phosphate cements are used as synthetic bone grafts, with several advantages, such as their osteoconductivity and injectability. Moreover, their low-temperature setting reaction and intrinsic porosity allow for the incorporation of drugs and active principles in the material. It is the aim of the present work to: a) provide an overview of the different approaches taken in the application of calcium phosphate cements for drug delivery in the skeletal system, and b) identify the most significant achievements. The drugs or active principles associated to calcium phosphate cements are classified in three groups, i) low molecular weight drugs; ii) high molecular weight biomolecules; and iii) ions.

JTD Keywords: Antibiotic, Bioceramic, Biomaterial, Bone regeneration, Calcium phosphate cement, Ceramic matrix, Growth factor, Hydroxyapatite, Ions, Protein

Cell tracking is an emergent area in nano-biotechnology, promising the study of individual cells or the identification of populations of cultured cells. In our approach, microtools designed for extracellular tagging are prepared, because using biofunctionalized polysilicon barcodes to tag cell membranes externally avoids the inconveniences of cell internalization. The crucial covalent biofunctionalization process determining the ultimate functionality was studied in order to find the optimum conditions to link a biomolecule to a polysilicon barcode surface using a self-assembled monolayer (SAM) as the connector. Specifically, a lectin (wheat germ agglutinin, WGA) was used because of its capacity to recognize some specific carbohydrates present on the surface of most mammalian cells. Self-assembled monolayers were prepared on polysilicon surfaces including aldehyde groups as terminal functions to study the suitability of their covalent chemical bonding to WGA. Some parameters, such as the polysilicon surface roughness or the concentration of WGA, proved to be crucial for successful biofunctionalization and bioactivity. The SAMs were characterized by contact angle measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS), and atomic force microscopy (AFM). The biofunctionalization step was also characterized by fluorescence microscopy and, in the case of barcodes, by adhesion experiments to the zona pellucida of mouse embryos. These experiments showed high barcode retention rates after 96 h of culture as well as high embryo viability to the blastocyst stage, indicating the robustness of the biofunctionalization and, therefore, the potential of these new microtools to be used for cell tagging.

JTD Keywords: Self-assembled monolayers, Wheat-germ-agglutinin, Protein immobilization strategies, Mass-spectrometry, Cell-surface, Petide, Binding, Identifications, Nanoparticles, Recognition

The excellent self-assembling properties of DNA and the excellent specificity of the antibodies to detect analytes of small molecular weight under competitive conditions have been combined in this study. Three oligonucleotide sequences (N(1)up, N(2)up, and N(3)up) have been covalently attached to three steroidal haptens (8, hG, and 13) of three anabolic-androgenic steroids (AAS), stanozolol (ST), tetrahydrogestrinone (THG), and boldenone (B), respectively. The synthesis of steroid oligonucleotide conjugates has been performed by the reaction of oligonucleotides carrying amino groups with carboxyl acid derivatives of steroidal haptens. Due to the chemical nature of the steroid derivatives, two methods for coupling the haptens and the ssDNA have been studied: a solid-phase coupling strategy and a solution-phase coupling strategy. Specific antibodies against ST, THG, and B have been used in this study to asses the possibility of using the self-assembling properties of the DNA to prepare biofunctional SPR gold chips based on the immobilization of haptens, by hybridization with the complementary oligonucleotide strands possessing SH groups previously immobilized. The capture of the steroid oligonucleotide conjugates and subsequent binding of the specific antibodies can be monitored on the sensogram due to variations produced on the refractive index on top of the gold chip. The resulting steroid oligonucleotide conjugates retain the hybridization and specific binding properties of oligonucleotides and haptens as demonstrated by thermal denaturation experiments and surface plasmon resonance (SPR).

JTD Keywords: Directed protein immobilization, Plasmon resonance biosensor, Self-assembled monolayers, Label-free, Serum samples, Assay, Immunoassays, Antibodies, Progress, Binding

In this work we report the fabrication and characterization of a label-free impedimetric immunosensor based on a silicon nitride (Si 3N 4) surface for the specific detection of human serum albumin (HSA) proteins. Silicon nitride provides several advantages compared with other materials commonly used, such as gold, and in particular in solid-state physics for electronic-based biosensors. However, few Si 3N 4-based biosensors have been developed; the lack of an efficient and direct protocol for the integration of biological elements with silicon-based substrates is still one of its the main drawbacks. Here, we use a direct functionalization method for the direct covalent binding of monoclonal anti-HSA antibodies on an aldehyde-functionalized Si-p/SiO 2/Si 3N 4 structure. This methodology, in contrast with most of the protocols reported in literature, requires less chemical reagents, it is less time-consuming and it does not need any chemical activation. The detection capability of the immunosensor was tested by performing non-faradaic electrochemical impedance spectroscopy (EIS) measurements for the specific detection of HSA proteins. Protein concentrations within the linear range of 10 -13-10 -7M were detected, showing a sensitivity of 0.128ΩμM -1 and a limit of detection of 10 -14M. The specificity of the sensor was also addressed by studying the interferences with a similar protein, bovine serum albumin. The results obtained show that the antibodies were efficiently immobilized and the proteins detected specifically, thus, establishing the basis and the potential applicability of the developed silicon nitride-based immunosensor for the detection of proteins in real and more complex samples.

JTD Keywords: Aldehyde, Electrochemical impedance spectroscopy, Human serum albumin, Immunosensor, Silicon nitride, Bovine serum albumins, Chemical reagents, Complex samples, Covalent binding, Detection capability, Electrochemical impedance, Electrochemical impedance spectroscopy measurements, Functionalizations, Human serum albumins, Impedimetric immunosensors, Label free, Limit of detection, Linear range, Protein concentrations, Silicon-based, Specific detection, Aldehydes

The formation of aggregates by misfolded proteins is thought to be inherently toxic, affecting cell fitness. This observation has led to the suggestion that selection against protein aggregation might be a major constraint on protein evolution. The precise fitness cost associated with protein aggregation has been traditionally difficult to evaluate. Moreover, it is not known if the detrimental effect of aggregates on cell physiology is generic or depends on the specific structural features of the protein deposit. In bacteria, the accumulation of intracellular protein aggregates reduces cell reproductive ability, promoting cellular aging. Here, we exploit the cell division defects promoted by the intracellular aggregation of Alzheimer's-disease-related amyloid β peptide in bacteria to demonstrate that the fitness cost associated with protein misfolding and aggregation is connected to the protein sequence, which controls both the in vivo aggregation rates and the conformational properties of the aggregates. We also show that the deleterious impact of protein aggregation on bacterial division can be buffered by molecular chaperones, likely broadening the sequential space on which natural selection can act. Overall, the results in the present work have potential implications for the evolution of proteins and provide a robust system to experimentally model and quantify the impact of protein aggregation on cell fitness.

JTD Keywords: Amyloid fibrils, Chaperones, Escherichia coli, Inclusion bodies, Protein aggregation

Cells from lung and other tissues are subjected to forces of opposing directions that are largely transmitted through integrin-mediated adhesions. How cells respond to force bidirectionality remains ill defined. To address this question, we nanofabricated flat-ended cylindrical Atomic Force Microscopy (AFM) tips with ~1 μm 2 cross-section area. Tips were uncoated or coated with either integrin-specific (RGD) or non-specific (RGE/BSA) molecules, brought into contact with lung epithelial cells or fibroblasts for 30 s to form focal adhesion precursors, and used to probe cell resistance to deformation in compression and extension. We found that cell resistance to compression was globally higher than to extension regardless of the tip coating. In contrast, both tip-cell adhesion strength and resistance to compression and extension were the highest when probed at integrin-specific adhesions. These integrin-specific mechanoresponses required an intact actin cytoskeleton, and were dependent on tyrosine phosphatases and Ca 2+ signaling. Cell asymmetric mechanoresponse to compression and extension remained after 5 minutes of tip-cell adhesion, revealing that asymmetric resistance to force directionality is an intrinsic property of lung cells, as in most soft tissues. Our findings provide new insights on how lung cells probe the mechanochemical properties of the microenvironment, an important process for migration, repair and tissue homeostasis.

JTD Keywords: Arginylglycylaspartic acid, Arginylglycylglutamic acid, Bovine serum albumin, Calcium ion, Integrin, Protein tyrosine phosphatase, Unclassified drug

Knowledge of the natural roles of cellular prion protein (PrPC) is essential to an understanding of the molecular basis of prion pathologies. This GPIanchored protein has been described in synaptic contacts, and loss of its synaptic function in complex systems may contribute to the synaptic loss and neuronal degeneration observed in prionopathy. In addition, Prnp knockout mice show enhanced susceptibility to several excitotoxic insults, GABAA receptor-mediated fast inhibition was weakened, LTP was modified and cellular stress increased. Although little is known about how PrPC exerts its function at the synapse or the downstream events leading to PrPCmediated neuroprotection against excitotoxic insults, PrPC has recently been reported to interact with two glutamate receptor subunits (NR2D and GluR6/7). In both cases the presence of PrPC blocks the neurotoxicity induced by NMDA and Kainate respectively. Furthermore, signals for seizure and neuronal cell death in response to Kainate in Prnp knockout mouse are associated with JNK3 activity, through enhancing the interaction of GluR6 with PSD-95. In combination with previous data, these results shed light on the molecular mechanisms behind the role of PrPC in excitotoxicity. Future experimental approaches are suggested and discussed.

JTD Keywords: Prion protein, Excitotoxicity, Neuroprotection, Glutamate receptors, Synapse, prionopathy

An understanding of protein adsorption process is crucial for designing biomaterial surfaces. In this work, with the use of a quartz-crystal microbalance with dissipation monitoring, we researched the following: (a) the kinetics of adsorption on TiO2 surfaces of three extensively described proteins that are relevant for metallic implant integration [i.e., albumin (BSA), fibrinogen (Fbg), and fibronectin (Fn)]; and (b) the competition of those proteins for adsorbing on TiO2 in a two-step experiment consisted of sequentially exposing the surfaces to different monoprotein solutions. Each protein showed a different process of adsorption and properties of the adlayer-calculated using the Voigt model. The competition experiments showed that BSA displaced larger proteins such as Fn and Fbg when BSA was introduced as the second protein in the system, whereas the larger proteins laid on top of BSA forming an adsorbed protein bi-layer when those were introduced secondly in the system.

JTD Keywords: QCM, Human plasma fibronectin, Induced conformational-changes, Von-willebrand-factor, BSA, Protein adsortion, Polymer surfaces, Solid-surfaces, Viscoelastic properties, Globular-proteins

Micro and nanoscale protein patterning based on microcontact printing technique on large substrates have often resolution problems due to roof collapse of the poly(dimethylsiloxane) (PDMS) stamps used. Here, we describe a technique that overcomes these issues by using instead a stamp made of poly(methyl methacrylate) (PMMA), a much more rigid polymer that do not collapse even using stamps with very high aspect ratios (up to 300:1). Conformal contact between the stamp and the substrate is achieved because of the homogeneous pressure applied via the nanoimprint lithography instrument, and it has allowed us to print lines of protein 150 nm wide, at a 400 nm period. This technique, therefore, provides an excellent method for the direct printing of high-density submicrometer scale patterns, or, alternatively, micro/nanopatterns spaced at large distances.

JTD Keywords: Microcontact printing, Nanoimprint lithography, Poly(methyl methacrylate), Protein

We present a method to measure directly and at the single-molecule level the distance decay constant that characterizes the rate of electron transfer (ET) in redox proteins. Using an electrochemical tunneling microscope under bipotentiostatic control, we obtained current-distance spectroscopic recordings of individual redox proteins confined within a nanometric tunneling gap at a well-defined molecular orientation. The tunneling current decays exponentially, and the corresponding decay constant (β) strongly supports a two-step tunneling ET mechanism. Statistical analysis of decay constant measurements reveals differences between the reduced and oxidized states that may be relevant to the control of ET rates in enzymes and biological electron transport chains.

JTD Keywords: Long-range electron transfer (LRET), Distance decay constant, Single-molecule electrochemistry, Redox enzyme, Metalloprotein, Blue copper protein, Azurin, Electrochemical scanning tunneling microscopy and spectroscopy, Nanoelectrodes, Debye length, Electrochemical charge screening

Ler, a member of the H-NS protein family, is the master regulator of the LEE pathogenicity island in virulent Escherichia coli strains. Here, we determined the structure of a complex between the DNA-binding domain of Ler (CT-Ler) and a 15-mer DNA duplex. CT-Ler recognizes a preexisting structural pattern in the DNA minor groove formed by two consecutive regions which are narrower and wider, respectively, compared with standard B-DNA. The compressed region, associated with an AT-tract, is sensed by the side chain of Arg90, whose mutation abolishes the capacity of Ler to bind DNA. The expanded groove allows the approach of the loop in which Arg90 is located. This is the first report of an experimental structure of a DNA complex that includes a protein belonging to the H-NS family. The indirect readout mechanism not only explains the capacity of H-NS and other H-NS family members to modulate the expression of a large number of genes but also the origin of the specificity displayed by Ler. Our results point to a general mechanism by which horizontally acquired genes may be specifically recognized by members of the H-NS family.

JTD Keywords: Enteropathogenic escherichia-coli, Nucleoid-associated protein, Nmr structure determination, Encoded regulator ler, Controls expression, Binding domain

Proteins are fundamental molecules in biology that are also involved in a wide range of industrial and biotechnological processes. Consequently, many works in the literature have been devoted to the study of protein-protein and protein-surface interactions in aqueous solutions. The results have been usually interpreted within the frame of the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory for colloidal systems. However, against the DLVO predictions, striking evidence of repulsive forces between proteins at high salt concentrations has been observed in different works based on the analysis of the second virial coefficient or on the direct measurement of protein interaction with an atomic force microscope. Hydration forces due to the adsorption of hydrated cations onto the negatively charged protein surfaces have been invoked to rationalize this anomalous repulsion. The hydration forces between proteins provide protein-covered particles with a non-DLVO colloidal stability at high salt concentrations, as different studies in the literature has proven. This review summarizes the most relevant results published so far on the presence of hydration forces between proteins and protein-coated colloidal particles.

JTD Keywords: Colloidal particles, Colloidal stability, Hydrated ions, Hydration forces, Proteins

Cellular prion protein (PrP(C)) is a glycosyl-phosphatidylinositol-anchored glycoprotein. When mutated or misfolded, the pathogenic form (PrP(SC)) induces transmissible spongiform encephalopathies. In contrast, PrP(C) has a number of physiological functions in several neural processes. Several lines of evidence implicate PrP(C) in synaptic transmission and neuroprotection since its absence results in an increase in neuronal excitability and enhanced excitotoxicity in vitro and in vivo. Furthermore, PrP(C) has been implicated in the inhibition of N-methyl-D-aspartic acid (NMDA)-mediated neurotransmission, and prion protein gene (Prnp) knockout mice show enhanced neuronal death in response to NMDA and kainate (KA). In this study, we demonstrate that neurotoxicity induced by KA in Prnp knockout mice depends on the c-Jun N-terminal kinase 3 (JNK3) pathway since Prnp(%) Jnk3(%) mice were not affected by KA. Pharmacological blockage of JNK3 activity impaired PrP(C)-dependent neurotoxicity. Furthermore, our results indicate that JNK3 activation depends on the interaction of PrP(C) with postsynaptic density 95 protein (PSD-95) and glutamate receptor 6/7 (GluR6/7). Indeed, GluR6-PSD-95 interaction after KA injections was favored by the absence of PrP(C). Finally, neurotoxicity in Prnp knockout mice was reversed by an AMPA/KA inhibitor (6,7-dinitroquinoxaline-2,3-dione) and the GluR6 antagonist NS-102. We conclude that the protection afforded by PrP(C) against KA is due to its ability to modulate GluR6/7-mediated neurotransmission and hence JNK3 activation.

JTD Keywords: Ischemic brain-injury, Prion protein PrP(C), Stress-inducible protein-1, Synaptic plasticity, Neurite outgrowth, Signaling module, Caspase-3 activation, Organotypic cultures, Cerebral-ischemia

Apart from the paradigm that cell-biomaterials interaction depends on the adsorption of soluble adhesive proteins we anticipate that upon distinct conditions also other, less soluble ECM proteins such as collagens, associate with the biomaterials interface with consequences for cellular response that might be of significant bioengineering interest. Using atomic force microscopy (AFM) we seek to follow the nanoscale behavior of adsorbed type IV collagen (Col IV)-a unique multifunctional matrix protein involved in the organization of basement membranes (BMs) including vascular ones. We have previously shown that substratum wettability significantly affects Col IV adsorption pattern, and in turn alters endothelial cells interaction. Here we introduce two new model surfaces based on self-assembled monolayers (SAMs), a positively charged - NH(2), and negatively charged -COOH surface, to learn more about their particular effect on Col IV behavior. AFM studies revealed distinct pattern of Col IV assembly onto the two SAMs resembling different aspects of network-like structure or aggregates (suggesting altered protein conformation). Moreover, the amount of adsorbed FITC-labeled Col IV was quantified and showed about twice more protein on NH(2) substrata. Human umbilical vein endothelial cells attached less efficiently to Col IV adsorbed on negatively charged COOH surface judged by altered cell spreading, focal adhesions formation, and actin cytoskeleton development. Immunofluorescence studies also revealed better Col IV recognition by both alpha(1) and alpha(2) integrins on positively charged NH(2) substrata resulting in higher phosphorylated focal adhesion kinase recruitment in the focal adhesion complexes. On COOH surface, no integrin clustering was observed. Taken altogether these results, point to the possibility that combined NH(2) and Col IV functionalization may support endothelization of cardiovascular implants.

JTD Keywords: Collagen type IV, SAMs, AFM, Surface-induced protein assembly, Endothelial cells, Vascular grafts

Proteins of the Hha/YmoA family co-regulate with H-NS the expression of horizontally acquired genes in Enterobacteria. Systematic mutations of conserved acidic residues in Hha have allowed the identification of D48 as an essential residue for H-NS binding and the involvement of E25. Mutations of these residues resulted in deregulation of sensitive genes in vivo. D48 is only partially solvent accessible, yet it defines the functional binding interface between Hha and H-NS confirming that Hha has to undergo a conformational change to bind H-NS. Exposed acidic residues, such as E25, may electrostatically facilitate and direct the approach of Hha to the positively charged region of H-NS enabling the formation of the final complex when D48 becomes accessible by a conformational change of Hha. Structured summary of protein interactions: YdgT and H-NS bind by nuclear magnetic resonance (View interaction) Hha and H-NS bind by nuclear magnetic resonance (View Interaction 1, 2, 3) Hha physically interacts with H-NS by pull down (View Interaction 1, 2).

JTD Keywords: Nucleoid associated protein, H-NS, Hha, Transcription repression

Five peptide sequences corresponding to the E1 protein of GBV-C [NCCAPEDIGFCLEGGCLV (P7), APEDIGFCLEGGCLVALG (P8), FCLEGGCLVALGCTICTD (P10), QAGLAVRPGKSAAQLVGE (P18), and AQLVGELGSLYGPLSVSA (P22)] were synthesized because they were capable of interfering with the HIV-1 fusion peptide (HIV-1 FP)-vesicle interaction. In this work the interaction of these peptides with the HIV-1 FP, as well as with membrane models, was analyzed to corroborate their inhibition ability and to understand if the interaction with the fusion peptide takes place in solution or at the membrane level. Several studies were carried out on aggregation and membrane fusion, surface Plasmon resonance, and conformational analysis by circular dichroism. Moreover, in vitro toxicity assays, including cytotoxicity studies in 3T3 fibroblasts and hemolysis assays in human red blood cells, were performed to evaluate if these peptides could be potentially used in anti-HIV-1 therapy. Results show that P10 is not capable of inhibiting membrane fusion caused by HIV-1 and it aggregates liposomes and fuses membranes, thus we decided to discard it for futures studies. P18 and P22 do not inhibit membrane fusion, but they inhibit the ability of HIV-1 FP to form pores in bilayers, thus we have not discarded them yet. P7 and P8 were selected as the best candidates for future studies because they are capable of inhibiting membrane fusion and the interaction of HIV-1 FP with bilayers. Therefore, these peptides could be potentially used in future anti-HIV-1 research. Part of the gang: Liposomes are deposited on a surface plasmon resonance chip (see AFM image of the chip) to observe the interaction of peptides corresponding to the E1 envelop protein of the hepatitis G virus with membranes to show how they reduce the interaction of the HIV-1 fusion peptide.

JTD Keywords: HIV-1 fusion protein, Liposomes, Membranes, Peptides, Viruses

Cellular microarray developments and its applications are the next step after DNA and protein microarrays. The choice of the surface chemistry of the substrates used for the implementation of this technique, that must favor proper protein immobilization while avoiding cell adhesion on the nonspotted areas, presents a complex challenge. This is a key issue since usually the best nonfouling surfaces are also the ones that retain immobilized the smallest amounts of printed protein. To quantitatively assess the amount of protein immobilization, in this study several combinations of fluorescently labeled fibronectin (Fn*) and streptavidin (SA*) were microspotted, with and without glycerol addition in the printing buffer, on several substrates suitable for cellular microarrays. The substrates assayed included chemically activated surfaces as well as Poly ethylene oxide (PEO) films that are nonfouling in solution but accept adhesion of proteins in dry conditions. The results showed that the spotted Fn* was retained by all the surfaces, although the PEO surface did show smaller amounts of immobilization. The SA*, on the other hand, was only retained by the chemically activated surfaces. The inclusion of glycerol in the printing buffer significantly reduced the immobilization of both proteins. The results presented in this article provide quantitative evidence of the convenience of using a chemically activated surface to immobilize proteins relevant for cellular microarray applications, particularly when ECM proteins are cospotted with smaller factors which are more difficult to be retained by the surfaces.

JTD Keywords: Protein immobilization, Quantification, Microarray, Substrate, Surface chemistry

New apatite (AP)/nanodiamond (ND) coating has been developed to improve physical and biological properties of stainless steel (SS) versus single AP coating. Homogeneously electrodeposited AP-ND layer demonstrates increased mechanical strength, interlayer cohesion and ductility. In the absence of serum, osteoblast-like MG63 cells attach well but poorly spread on both AP and AP-ND substrata. Pre-adsorption with serum or fibronectin (FN) improves the cellular interaction-an effect that is better pronounced on the AP-ND coating. In single protein adsorption study fluorescein isothiocyanate-labeled FN (FITC-FN) shows enhanced deposition on the AP-ND layer consistent with the significantly improved cell adhesion, spreading and focal adhesions formation (in comparison to SS and AP), particularly at low FN adsorption concentrations (1 mu g/ml). Higher FN concentrations (20 mu g/ml) abolish this difference suggesting that the promoted cellular interaction of serum (where FN is low) is caused by the greater affinity for FN. Moreover, it is found that MG63 cells tend to rearrange both adsorbed and secreted FN on the AP-ND layer suggesting facilitated FN matrix formation.

JTD Keywords: Extracellular-matrix, Protein adsorption, Integrins, Adhesion, Biomaterials, Surfaces, Polymerization, Composite, Implants, Titanium

Horizontal gene transfer (HGT), non-hereditary transfer of genetic material between organisms, accounts for a significant proportion of the genetic variability in bacteria. In Gram negative bacteria, the nucleoid-associated protein H-NS silences unwanted expression of recently acquired foreign DNA. This, in turn, facilitates integration of the incoming genes into the regulatory networks of the recipient cell. Bacteria belonging to the family Enterobacteriaceae express an additional protein, the Hha protein that, by binding to H-NS, potentiates silencing of HGT DNA. We provide here an overview of Hha-like proteins, including their structure and function, as well as their evolutionary relationship. We finally present available information suggesting that, by expressing Hha-like proteins, bacteria such as Escherichia coli facilitate HGT incorporation and hence, the impact of HGT in their genetic diversity.

JTD Keywords: Hha, H-NS, HGT DNA, Enterobacteria, Nucleoid-associated proteins, Enterica serovar typhimurium, Histone-like protein, h-ns, Escherichia-coli, Yersinia-enterocolitica, Salmonella-enterica

Aptamers are single stranded artificial nucleic acid ligands that can be generated against almost any kind of target, such as ions, metabolites aminoacids, drugs, toxins, proteins or whole cells. They are isolated from combinatorial libraries of synthetic nucleic acids by an iterative process of adsorption, recovery and amplification, know as SELEX (Systematic Evolution of Ligands by EXponential enrichment) process. Aptamers, the nucleic acid equivalent to antibodies, are easy to synthesise, is not required the use of animals for its synthesis, for this reason it can be developed again toxins and small molecules that do not produce immune response in animals and can be tuned for affinity in closer to assay conditions permitting recognition out of the physiological state. So, aptamers posses numerous advantages that make them preferred candidates as biorecognition elements. In view of the advantages and simple structure of aptamers, they have been used in a wide range of applications such as therapeutics, diagnosis, chromatography, environmental detection, among other.

JTD Keywords: Aptamers, Biosensors, Protein recognition

We present a method for using long-term organotypic slice co-cultures of the entorhino-hippocampal formation to analyze the axon-regenerative properties of a determined compound. The culture method is based on the membrane interphase method, which is easy to perform and is generally reproducible. The degree of axonal regeneration after treatment in lesioned cultures can be seen directly using green fluorescent protein (GFP) transgenic mice or by axon tracing and histological methods. Possible changes in cell morphology after pharmacological treatment can be determined easily by focal in vitro electroporation. The well-preserved cytoarchitectonics in the co-culture facilitate the analysis of identified cells or regenerating axons. The protocol takes up to a month.

JTD Keywords: Cajal-retzius cells, Green-fluorescent-protein, In-vitro model, Rat hippocampus, Nervous-tissue, Brain-slices, Dentate gyrus, Gene-transfer, Cultures, Damage

We investigated self-adhesion between highly negatively charged aggrecan macromolecules extracted from bovine cartilage extracellular matrix by performing atomic force microscopy (AFM) imaging and single-molecule force spectroscopy (SMFS) in saline solutions. By controlling the density of aggrecan molecules on both the gold substrate and the gold-coated tip surface at submonolayer densities, we were able to detect and quantify the Ca2+-dependent homodimeric interaction between individual aggrecan molecules at the single-molecule level. We found a typical nonlinear sawtooth profile in the AFM force-versus-distance curves with a molecular persistence length of I-p = 0.31 +/- 0.04 nm. This is attributed to the stepwise dissociation of individual glycosaminoglycan (GAG) side chains in aggrecans, which is very similar to the known force fingerprints of other cell adhesion proteoglycan systems. After studying the GAG-GAG dissociation in a dynamic, loading-rate-dependent manner (dynamic SMFS) and analyzing the data according to the stochastic Bell-Evans model for a thermally activated decay of a metastable state under an external force, we estimated for the single glycan interaction a mean lifetime of tau = 7.9 +/- 4.9 s and a reaction bond length of x(beta) = 0.31 +/- 0.08 nm. Whereas the x(beta)-value compares well with values from other cell adhesion carbohydrate recognition motifs in evolutionary distant marine sponge proteoglycans, the rather short GAG interaction lifetime reflects high intermolecular dynamics within aggrecan complexes, which may be relevant for the viscoelastic properties of cartilage tissue.

JTD Keywords: Bovine nasal cartilage, Articular-cartilage, Sinorhizobium-meliloti, Proteoglycan, Microscopy, DNA, Macromolecules, Binding, Protein, Glycosaminoglycans

The specific functional structure of natural proteins is determined by the way in which amino acids are sequentially connected in the polypeptide. The tight sequence/structure relationship governing protein folding does not seem to apply to amyloid fibril formation because many proteins without any sequence relationship have been shown to assemble into very similar β-sheet-enriched structures. Here, we have characterized the aggregation kinetics, seeding ability, morphology, conformation, stability, and toxicity of amyloid fibrils formed by a 20-residue domain of the islet amyloid polypeptide (IAPP), as well as of a backward and scrambled version of this peptide. The three IAPP peptides readily aggregate into ordered, β-sheet-enriched, amyloid-like fibrils. However, the mechanism of formation and the structural and functional properties of aggregates formed from these three peptides are different in such a way that they do not cross-seed each other despite sharing a common amino acid composition. The results confirm that, as for globular proteins, highly specific polypeptide sequential traits govern the assembly pathway, final fine structure, and cytotoxic properties of amyloid conformations.

JTD Keywords: Amyloid formation, Islet amyloid polypeptide, Protein aggregation, Protein sequence, Retro proteins

Vitronectin (VN) adsorption on a family of model substrates consisting of copolymers of ethyl acrylate and hydroxyl ethylacrylate in different ratios (to obtain a controlled surface density of -OH groups) was investigated by Atomic Force Microscopy (AFM). It is shown that the fraction of the substrate covered by the protein depends strongly on the amount of hydroxyl groups in the sample and it monotonically decreases as the -OH density increases. Isolated globular-like VN molecules are observed on the surfaces with the higher OH density. As the fraction of hydroxyl groups decreases, aggregates of 3-5 VN molecules are observed on the sample. Overall cell morphology, focal adhesion formation and actin cytoskeleton development are investigated to assess the biological activity of the adsorbed VN on the different surfaces. Dermal fibroblast cells show excellent material interaction on the more hydrophobic samples (OH contents lower than 0.5), which reveals enhanced VN activity on this family of substrates as compared with other extracellular matrix proteins (e.g., fibronectin and fibrinogen).

JTD Keywords: Copolymers, Vitronectin, AFM, Self-assembled monolayers, Cell-adhesion, Thermal transitions, Protein adsorption, Surfaces, Fibronectin, Biomaterials, Attachment, Fibrinogen

In this work, we report the detection of proteins by means of simultaneous fluorescence and impedance measurements in a cyclo olefin polymer (COP) chip containing an ordered pillar array column, used for reversed-phase liquid chromatography, with integrated microband gold electrodes at the end of the channel.

JTD Keywords: Cyclo olefin polymer, Gold microelectrodes, Impedance, Pillar array, Protein detection

The initial cellular events that take place at the biomaterials interface mimic to a certain extent the natural adhesive interaction of cells with the extracellular matrix (ECM) (Spie, 2002; Griffin & Naughton, 2002; Grinnell, 1986). In fact, the living cells cannot interact directly with foreign materials, but they readily attach to the adsorbed layer of proteins (upon contact with physiological fluids in vivo or culture medium in vitro) such as fibronectin (FN), vitronectin (VN), fibrinogen (FG), representing the so-called soluble matrix proteins in the biological fluids (Grinnell 1986).

JTD Keywords: Tissue Engineering, Protein-material interaction, ECM, Biomaterials

Summary form only given. Commercially pure titanium (cp Ti) dental implants have been widely and successfully used with high rates of clinical success in normal situations. However, there is still a lack of reliable synthetic materials to be used either a) when immediate loading of the implant is desired or b) when bone presents compromised conditions due to trauma, infection, systemic disease and/or lack of significant bone volume. Our group has aimed the development of biomimetic strategies of surface modification to obtain metallic implants with osteostimulative capabilities. These surface modifications will provide implants with a rapid rate of newly-formed bone growth and with ossecoalescence, i.e., direct chemical contact with the surrounding tissues. Consequently, the biomimetically-modified implants will be reliably used on those more demanding clinical situations, cp Ti surfaces treated to obtain a combination of an optimal random surface topography (in the micro and nanolevels) with a chemical modification of the naturally-formed titania layer have been proved bioactive. These rough and bioactive surfaces nucleate and grow a homogeneous hydroxyapatite layer both in vitro and in vivo. They stimulate the osteoblasts differentiation and trigger a rapid bone formation that mechanically fixes implants under immediate-loading conditions. A simple process using silane chemistry has been proved specific, rapid, and reliable to covalently immobilize biomolecules on cp Ti surfaces. This methodology can be used to develop biofunc- tionalized implant surfaces with different or combined bioactivities. The biofunctional molecules can be biopolymers, proteins, growth factors, and synthetic peptides specifically designed to be attached to the surface. The bioactive properties of the molecules designed and used can be mineral growing and nucleation, osteoblast differentiation (bone regeneration), fibroblasts differentiation (biological sealing), antibiotic,... Specifically, we have obtained mechanically and thermochemically stable coatings made of recombinant elastin-like biopolymers. The biopolymers bear either a) the RODS peptide, which is a highly-specific cell-adhesion motif present in proteins of the extracellular matrix for different tissues including bone, or b) an acidic peptide sequence derived from statherin, a protein present in saliva with high affinity for calcium-phosphates and with a leading role in the remineralization processes of the hard tissues forming our teeth. Two different biomimetic strategies have been successfully developed combining topographical modification, inorganic treatments and/or biofunctionalization for improving bioactive integrative properties of cp Ti implants.

JTD Keywords: Biomedical materials, Bone, Cellular biophysics, Dentistry, Molecular biophysics, Prosthetics, Proteins, Surface treatment, Titanium

We present the experimental demonstration of low-frequency dielectric constant imaging of single-layer supported biomembranes at the nanoscale. The dielectric constant image has been quantitatively reconstructed by combining the thickness and local capacitance obtained using a scanning force microscope equipped with a sub-attofarad low-frequency capacitance detector. This work opens new possibilities for studying bioelectric phenomena and the dielectric properties of biological membranes at the nanoscale.

JTD Keywords: Atomic-force microscopy, Nnear-field microscopy, Purple membrane, Scanning capacitance, Biological-systems, Fluid, Spectroscopy, Resolution, Proteins, Dynamics

Horizontal acquisition of DNA by bacteria dramatically increases genetic diversity and hence successful bacterial colonization of several niches, including the human host. A relevant issue is how this newly acquired DNA interacts and integrates in the regulatory networks of the bacterial cell. The global modulator H-NS targets both core genome and HGT genes and silences gene expression in response to external stimuli such as osmolarity and temperature. Here we provide evidence that H-NS discriminates and differentially modulates core and HGT DNA. As an example of this, plasmid R27-encoded H-NS protein has evolved to selectively silence HGT genes and does not interfere with core genome regulation. In turn, differential regulation of both gene lineages by resident chromosomal H-NS requires a helper protein: the Hha protein. Tight silencing of HGT DNA is accomplished by H-NS-Hha complexes. In contrast, core genes are modulated by H-NS homoligomers. Remarkably, the presence of Hha-like proteins is restricted to the Enterobacteriaceae. In addition, conjugative plasmids encoding H-NS variants have hitherto been isolated only from members of the family. Thus, the H-NS system in enteric bacteria presents unique evolutionary features. The capacity to selectively discriminate between core and HGT DNA may help to maintain horizontally transmitted DNA in silent form and may give these bacteria a competitive advantage in adapting to new environments, including host colonization.

JTD Keywords: 2A strain 2457T, Escherichia-Coli, Salmonella-Enterica, Protein, DNA, Expression, Binding, HHA, Shigella, Plasmid

Alzheimer's disease neuropathology is characterized by neuronal death, amyloid beta-peptide deposits and neurofibrillary tangles composed of paired helical filaments of tau protein. Although crucial for our understanding of the pathogenesis of Alzheimer's disease, the molecular mechanisms linking amyloid beta-peptide and paired helical filaments remain unknown. Here, we show that amyloid beta-peptide-induced nitro-oxidative damage promotes the nitrotyrosination of the glycolytic enzyme triosephosphate isomerase in human neuroblastoma cells. Consequently, nitro-triosephosphate isomerase was found to be present in brain slides from double transgenic mice overexpressing human amyloid precursor protein and presenilin 1, and in Alzheimer's disease patients. Higher levels of nitro-triosephosphate isomerase (P < 0.05) were detected, by Western blot, in immunoprecipitates from hippocampus (9 individuals) and frontal cortex (13 individuals) of Alzheimer's disease patients, compared with healthy subjects (4 and 9 individuals, respectively). Triosephosphate isomerase nitrotyrosination decreases the glycolytic flow. Moreover, during its isomerase activity, it triggers the production of the highly neurotoxic methylglyoxal (n = 4; P < 0.05). The bioinformatics simulation of the nitration of tyrosines 164 and 208, close to the catalytic centre, fits with a reduced isomerase activity. Human embryonic kidney (HEK) cells overexpressing double mutant triosephosphate isomerase (Tyr164 and 208 by Phe164 and 208) showed high methylglyoxal production. This finding correlates with the widespread glycation immunostaining in Alzheimer's disease cortex and hippocampus from double transgenic mice overexpressing amyloid precursor protein and presenilin 1. Furthermore, nitro-triosephosphate isomerase formed large beta-sheet aggregates in vitro and in vivo, as demonstrated by turbidometric analysis and electron microscopy. Transmission electron microscopy (TEM) and atomic force microscopy studies have demonstrated that nitro-triosephosphate isomerase binds tau monomers and induces tau aggregation to form paired helical filaments, the characteristic intracellular hallmark of Alzheimer's disease brains. Our results link oxidative stress, the main etiopathogenic mechanism in sporadic Alzheimer's disease, via the production of peroxynitrite and nitrotyrosination of triosephosphate isomerase, to amyloid beta-peptide-induced toxicity and tau pathology.

JTD Keywords: Alzheimer's disease, Amyloid β-peptide, Tau protein, Triosephosphate isomerase, Peroxynitrite

Background: Prionopathies are characterized by spongiform brain degeneration, myoclonia, dementia, and periodic electroencephalographic (EEG) disturbances. The hallmark of prioniopathies is the presence of an abnormal conformational isoform (PrPsc) of the natural cellular prion protein (PrPc) encoded by the Prnp gene. Although several roles have been attributed to PrPc, its putative functions in neuronal excitability are unknown. Although early studies of the behavior of Prnp knockout mice described minor changes, later studies report altered behavior. To date, most functional PrPc studies on synaptic plasticity have been performed in vitro. To our knowledge, only one electrophysiological study has been performed in vivo in anesthetized mice, by Curtis and coworkers. They reported no significant differences in paired-pulse facilitation or LTP in the CA1 region after Schaffer collateral/commissural pathway stimulation. Methodology/Principal Findings: Here we explore the role of PrPc expression in neurotransmission and neural excitability using wild-type, Prnp 2/2 and PrPc-overexpressing mice (Tg20 strain). By correlating histopathology with electrophysiology in living behaving mice, we demonstrate that both Prnp 2/2 mice but, more relevantly Tg20 mice show increased susceptibility to KA, leading to significant cell death in the hippocampus. This finding correlates with enhanced synaptic facilitation in paired-pulse experiments and hippocampal LTP in living behaving mutant mice. Gene expression profiling using IlluminaTM microarrays and Ingenuity pathways analysis showed that 129 genes involved in canonical pathways such as Ubiquitination or Neurotransmission were co-regulated in Prnp 2/2 and Tg20 mice. Lastly, RT-qPCR of neurotransmission-related genes indicated that subunits of GABAA and AMPA-kainate receptors are co-regulated in both Prnp 2/2 and Tg20 mice. Conclusions/Significance: Present results demonstrate that PrPc is necessary for the proper homeostatic functioning of hippocampal circuits, because of its relationships with GABAA and AMPA-Kainate neurotransmission. New PrPc functions have recently been described, which point to PrPc as a target for putative therapies in Alzheimer’s disease. However, our results indicate that a ‘‘gain of function’’ strategy in Alzheimer’s disease, or a ‘‘loss of function’’ in prionopathies, may impair PrPc function, with devastating effects. In conclusion, we believe that present data should be taken into account in the development of future therapies.

JTD Keywords: Prions, Prionopathies, Natural cellular prion protein (PrPc), Hippocampus, GABA (A) receptor, Glutamate Receptor

Proteins of the Hha/YmoA family co-regulate with H-NS the expression of virulence factors in Enterobacteriaceae. Vibrio cholerae lacks Hha-like proteins and its H-NS (vcH-NS) is unable to bind Hha, in spite of the conservation of a key residue for Hha binding by Escherichia coli H-NS (ecH-NS). Exchange of the residues in position 9 between vcH-NS and ecH-NS strongly reduces Hha binding by ecH-NS and introduces it in vcH- NS. These mutations strongly affect the repression of the hemolysin operon in E. coli and the electrophoretic mobility of complexes formed with a DNA fragment containing its regulatory region.

JTD Keywords: Nucleoid associated protein, H-NS, Hha, Transcription repression, NMR, Electrophoretic mobility shift assays

In this study, we compare for the first time the nanomechanical properties of lipid bilayer islands on flat and porous surfaces. 1,2-Dimyzistoyl-sn-glycero-3-phosphatidylcholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) bilayers were deposited on flat (silicon and mica) and porous silicon (pSi) substrate surfaces and examined using atomic force spectroscopy and force volume imaging. Force spectroscopy measurements revealed the effects of the underlying substrate and of the lipid phase on the nanomechanical properties of bilayers islands. For mica and silicon, significant differences in breakthrough force between the center and the edges of bilayer islands were observed for both phospolipids. These differences were more pronounced for DMPC than for DPPC, presumably due to melting effects at the edges of DMPC bilayers. In contrast, bilayer islands deposited on pSi yielded similar breakthrough forces in the central region and along the perimeter of the islands, and those values in turn were similar to those measured along the perimeter of bilayer islands deposited on the flat substrates. The study also demonstrates that pSi is suitable solid support for the formation of pore-spanning phospholipid bilayers with potential applications in transmembrane protein studies, drug delivery, and biosensing.

JTD Keywords: Black lipid-membranes, Gold surfaces, Supported bilayers, Channel activity, Micro-BLMS, Silicon, Proteins, Vesicles, AFM, Temperature measurement

The 2C-methylerythritol 4-phosphate (MEP) pathway for the biosynthesis of isopentenyl pyrophosphate and its isomer dimethylallyl pyrophosphate, which are the precursors of isoprenoids, is present in plants, in the malaria parasite Plasmodium falciparum and in most eubacteria, including pathogenic agents. However, the MEP pathway is absent from fungi and animals, which have exclusively the mevalonic acid pathway. Given the characteristics of the MEP pathway, its enzymes represent potential targets for the generation of selective antibacterial, antimalarial and herbicidal molecules. We have focussed on the enzyme 4-(cytidine 5'-diphospho)-2-C-methyl-D: -erythritol kinase (CMK), which catalyses the fourth reaction step of the MEP pathway. A molecular dynamics simulation was carried out on the CMK dimer complex, and protein-protein interactions analysed, considering also water-mediated interactions between monomers. In order to find small molecules that bind to CMK and disrupt dimer formation, interactions observed in the dynamics trajectory were used to model a pharmacophore used in database searches. Using an intensity-fading matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry approach, one compound was found to interact with CMK. The data presented here indicate that a virtual screening approach can be used to identify candidate molecules that disrupt the CMK-CMK complex. This strategy can contribute to speeding up the discovery of new antimalarial, antibacterial, and herbicidal compounds.

JTD Keywords: Solvent-mediated interactions, Protein-protein interactions, Molecular dynamics, Drug design, Intensisty-fading MALDI-TOF mass spectrometry

The influence of surface chemistry -substrates with controlled surface density of -OH groups- on fibronectin conformation and distribution is directly observed by Atomic Force Microscopy (AFM). FN fibrillogenesis, which is known to be a process triggered by interaction with integrins, is shown in our case to be induced by the substrate (in absence of cells), which is able to enhance FN-FN interactions leading to the formation of a protein network on the material surface. This phenomenon depends both on surface chemistry and protein concentration. The level of the FN fibrillogenesis was quantified by calculating the fractal dimension of the adsorbed protein from image analysis of the AFM results. The total amount of adsorbed FN is obtained by making use of a methodology which employs western-blotting combined with image analysis of the corresponding protein bands, with the lowest sensitivity threshold equal to 15 ng of adsorbed protein. Furthermore, FN adsorption is correlated to human osteoblast adhesion through morphology and actin cytoskeleton formation. Actin polymerization is in need of the formation of the protein network on the substrate's surface. Cell morphology is more rounded (as quantified by calculating the circularity of the cells by image analysis) the lower the degree of FN fibrillogenesis on the substrate.

JTD Keywords: Cell-adhesion, Conformational-changes, Electron-microscopy, Protein adsorption, Fractal dimension, Integrin binding, Biocompatibility, Monolayers, Matrix, Fibrillogenesis

Lately there has been an increasing interest in the development of tools that enable the high throughput analysis of combinations of surface-immobilized signaling factors and which examine their effect on stem cell biology and differentiation. These surface-immobilized factors function as artificial microenvironments that can be ordered in a microarray format. These microarrays could be useful for applications such as the study of stem cell biology to get a deeper understanding of their differentiation process. Here, the evaluation of several key process parameters affecting the cellular microarray fabrication is reported in terms of its effects on the mesenchymal stem cell culture time on these microarrays. Substrate and protein solution requirements, passivation strategies and cell culture conditions are investigated. The results described in this article serve as a basis for the future development of cellular microarrays aiming to provide a deeper understanding of the stem cell differentiation process.

JTD Keywords: Bone-marrow, Protein microarrays, Progenitor cells, Differentiation, Surfaces, Growth, Biomaterials, Commitment, Pathways, Culture media

Biological patterned surfaces having sub-micron scale resolution are of great importance in many fields of life science and biomedicine. Different techniques have been proposed for surface patterning at the nanoscale. However, most of them present some limitations regarding the patterned area size or are time-consuming. Micro/nanocontact printing is the most representative soft lithography-based technique for surface patterning at the nanoscale. Unfortunately, conventional micro/nanocontact printing also suffers from problems such as diffusion and stamp collapsing that limit pattern resolution. To overcome these problems, a simple way of patterning thiols under liquid media using submerged nanocontact printing (SnCP) over large areas (similar to cm(2)) achieving nanosize resolution is presented. The technique is also low cost and any special equipment neither laboratory conditions are required. Nanostructured poly(dimethyl siloxane) stamps are replicated from commercially available digital video disks. SnCP is used to stamp patterns of 200 nm 1-octadecanethiol lines in liquid media, avoiding ink diffusion and stamp collapsing, over large areas on gold substrates compared with conventional procedures. Atomic force microscopy measurements reveal that the patterns have been successfully transferred with high fidelity. This is an easy, direct, effective and low cost methodology for molecule patterning immobilization which is of interest in those areas that require nanoscale structures over large areas, such as tissue engineering or biosensor applications.

JTD Keywords: Submerged Nanocontact Printing, Replica Molding, Nanopatterning, Large Area, Dip-pen nanolithography, High-aspect-ratio, Soft lithography, Submicronscale, Nanoimprint lithography, Thin-film, Surfaces, Fabrication, Proteins, Nanofabrication

The histopathological hallmarks of Alzheimer disease are the self-aggregation of the amyloid beta peptide (A beta) in extracellular amyloid fibrils and the formation of intraneuronal Tau filaments, but a convincing mechanism connecting both processes has yet to be provided. Here we show that the endogenous polysaccharide chondroitin sulfate B (CSB) promotes the formation of fibrillar structures of the 42-residue fragment, A beta(1-42). Atomic force microscopy visualization, thioflavin T fluorescence, CD measurements, and cell viability assays indicate that CSB-induced fibrils are highly stable entities with abundant beta-sheet structure that have little toxicity for neuroblastoma cells. We propose a wedged cylinder model for A beta(1-42) fibrils that is consistent with the majority of available data, it is an energetically favorable assembly that minimizes the exposure of hydrophobic areas, and it explains why fibrils do not grow in thickness. Fluorescence measurements of the effect of different A beta(1-42) species on Ca2+ homeostasis show that weakly structured nodular fibrils, but not CSB-induced smooth fibrils, trigger a rise in cytosolic Ca2+ that depends on the presence of both extracellular and intracellular stocks. In vitro assays indicate that such transient, local Ca2+ increases can have a direct effect in promoting the formation of Tau filaments similar to those isolated from Alzheimer disease brains.

JTD Keywords: AFM, Alzheimers-disease, Chondroitin sulfate, Heparan-sulfate, Lipid-bilayers, Beta-peptide, In-vitro, Neurodegenerative diseases, Extracellular-matrix, Prion protein

The accumulation of aggregated protein in the cell is associated with the pathology of many diseases and constitutes a major concern in protein production. Intracellular aggregates have been traditionally regarded as nonspecific associations of misfolded polypeptides. This view is challenged by studies demonstrating that, in vitro, aggregation often involves specific interactions. However, little is known about the specificity of in vivo protein deposition. Here, we investigate the degree of in vivo co-aggregation between two self-aggregating proteins, A beta A2 amyloid peptide and foot-and-mouth disease virus VP1 capsid protein, in prokaryotic cells. In addition, the ultrastructure of intracellular aggregates is explored to decipher whether amyloid fibrils and intracellular protein inclusions share structural properties. The data indicate that in vivo protein aggregation exhibits a remarkable specificity that depends on the establishment of selective interactions and results in the formation of oligomeric and fibrillar structures displaying amyloid-like properties. These features allow prokaryotic A beta A2 intracellular aggregates to act as effective seeds in the formation of A beta A2 amyloid fibrils. overall, our results suggest that conserved mechanisms underlie protein aggregation in different organisms. They also have important implications for biotechnological and biomedical applications of recombinant polypeptides.

JTD Keywords: Protein aggregation, Inclusion bodies, Conformational diseases, Amyloid fibrils, Protein folding

In this study, we report that a single mutation of cysteine 18 to isoleucine (C18I) in Escherichia coli Hha abolishes the repression of the hemolysin operon observed in the wild-type protein. The phenotype also includes a significant decrease in the growth rate of E. coli cells at low ionic strength. Other substitutions at this position (C18A, C18S) have no observable effects in E. coli growth or hemolysin repression. All mutants are stable and well folded and bind H-NS in vitro with similar affinities suggesting that Cys 18 is not directly involved in H-NS binding but this position is essential for the activity of the H-NS/Hha heterocomplexes in the regulation of gene expression.

JTD Keywords: Nucleoid-associated protein, H-NS, Hha, Transcription repression

The H-NS protein plays a significant role in the modulation of gene expression in Gram-negative bacteria. Whereas isolation and characterization of hns mutants in Escherichia coli, Salmonella and Shigella represented critical steps to gain insight into the modulatory role of H-NS, it has hitherto not been possible to isolate hns mutants in Yersinia. The hns mutation is considered to be deleterious in this genus. To study the modulatory role of H-NS in Yersinia we circumvented hns lethality by expressing in Y. enterocolitica a truncated H-NS protein known to exhibit anti-H-NS activity in E. coli (H-NST(EPEC)). Y. enterocolitica cells expressing H-NST(EPEC) showed an altered growth rate and several differences in the protein expression pattern, including the ProV protein, which is modulated by H-NS in other enteric bacteria. To further confirm that H-NST(EPEC) expression in Yersinia can be used to demonstrate H-NS-dependent regulation in this genus, we used this approach to show that H-NS modulates expression of the YmoA protein.

JTD Keywords: Bacterial Proteins/biosynthesis/genetics/ physiology, DNA-Binding Proteins/biosynthesis/genetics/ physiology, Electrophoresis, Gel, Two-Dimensional, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Genes, Essential, Proteome/analysis, RNA, Bacterial/biosynthesis, RNA, Messenger/biosynthesis, Reverse Transcriptase Polymerase Chain Reaction, Sequence Deletion, Yersinia enterocolitica/chemistry/genetics/growth & development/ physiology

In this study we report on an experimental method based on dielectrophoretic analysis to identify changes in four Escherichia coli isogenic strains that differed exclusively in one mutant allele. The dielectrophoretic properties of wild-type cells were compared to those of hns, hha, and hha hns mutant derivatives. The hns and hha genes code respectively for the global regulators Hha and H-NS. The Hha and H-NS proteins modulate gene expression in Escherichia coli and other Gram negative bacteria. Mutations in either hha or hns genes result in a pleiotropic phenotype. A two-shell prolate ellipsoidal model has been used to fit the experimental data, obtained from dielectrophoresis measurements, and to study the differences in the dielectric properties of the bacterial strains. The experimental results show that the mutant genotype can be predicted from the dielectrophoretic analysis of the corresponding cultures, opening the way to the development of microdevices for specific identification. Therefore, this study shows that dielectrophoresis can be a valuable tool to study bacterial populations which, although apparently homogeneous, may present phenotypic variability.

JTD Keywords: H-NS, Dielectric behaviour, Hemolysin genes, Cells, Separation, Expression, Proteins, HHA, Electrorotation, Polarization