by Keyword: tubules

Garreta E, Nauryzgaliyeva Z, Marco A, Safi W, Montserrat N, (2022). Dissecting nephron morphogenesis using kidney organoids from human pluripotent stem cells Current Opinion In Genetics & Development 72, 22-29

During kidney development the emergence of complex multicellular shapes such as the nephron (the functional unit of the kidney) rely on spatiotemporally coordinated developmental programs. These involve gene regulatory networks, signaling pathways and mechanical forces, that work in concert to shape and form the nephron(s). The generation of kidney organoids from human pluripotent stem cells now represent an unprecedented experimental set up to study these processes. Here we discuss the potential applications of kidney organoids to advance our knowledge of how mechanical forces and cell fate specification spatiotemporally interact to orchestrate nephron patterning and morphogenesis in humans. Progress in innovative techniques for quantifying and perturbing these processes in a controlled manner will be crucial. A mechanistic understanding of the multicellular dynamic processes occurring during nephrogenesis will pave the way to unveil new mechanisms of human kidney disease. © 2021

JTD Keywords: differentiation, dynamics, induction, lumen formation, models, mouse, organogenesis, reveals, tubules, Divergent features

Tian, X., De Pace, C., Ruiz-Perez, L., Chen, B., Su, R., Zhang, M., Zhang, R., Zhang, Q., Wang, Q., Zhou, H., Wu, J., Zhang, Z., Tian, Y., Battaglia, G., (2020). A Cyclometalated iridium (III) complex as a microtubule probe for correlative super-resolution fluorescence and electron microscopy Advanced Materials 32, (39), 2003901

The visualization of microtubules by combining optical and electron microscopy techniques provides valuable information to understand correlated intracellular activities. However, the lack of appropriate probes to bridge both microscopic resolutions restricts the areas and structures that can be comprehended within such highly assembled structures. Here, a versatile cyclometalated iridium (III) complex is designed that achieves synchronous fluorescence–electron microscopy correlation. The selective insertion of the probe into a microtubule triggers remarkable fluorescence enhancement and promising electron contrast. The long-life, highly photostable probe allows live-cell super-resolution imaging of tubulin localization and motion with a resolution of ≈30 nm. Furthermore, correlative light–electron microscopy and energy-filtered transmission electron microscopy reveal the well-associated optical and electron signal at a high specificity, with an interspace of ≈41 Å of microtubule monomer in cells.

JTD Keywords: Correlation light–electron microscopy, Microtubules, Organometallic probes, Super-resolution microscopy

Barreto, S., Clausen, C. H., Perrault, C. M., Fletcher, D. A., Lacroix, D., (2013). A multi-structural single cell model of force-induced interactions of cytoskeletal components Biomaterials 34, (26), 6119-6126

Several computational models based on experimental techniques and theories have been proposed to describe cytoskeleton (CSK) mechanics. Tensegrity is a prominent model for force generation, but it cannot predict mechanics of individual CSK components, nor explain the discrepancies from the different single cell stimulating techniques studies combined with cytoskeleton-disruptors. A new numerical concept that defines a multi-structural 3D finite element (FE) model of a single-adherent cell is proposed to investigate the biophysical and biochemical differences of the mechanical role of each cytoskeleton component under loading. The model includes prestressed actin bundles and microtubule within cytoplasm and nucleus surrounded by the actin cortex. We performed numerical simulations of atomic force microscopy (AFM) experiments by subjecting the cell model to compressive loads. The numerical role of the CSK components was corroborated with AFM force measurements on U2OS-osteosarcoma cells and NIH-3T3 fibroblasts exposed to different cytoskeleton-disrupting drugs. Computational simulation showed that actin cortex and microtubules are the major components targeted in resisting compression. This is a new numerical tool that explains the specific role of the cortex and overcomes the difficulty of isolating this component from other networks invitro. This illustrates that a combination ofcytoskeletal structures with their own properties is necessary for a complete description of cellular mechanics.

JTD Keywords: Actin bundles, Actin cortex, AFM (atomic force microscopy), Cytoskeleton, Finite element modeling, Microtubules