CV Summary
Silvia Pittolo has a 5-year, Ramón-y-Cajal senior position at IBEC, funded by the Spanish Ministry of Science and Innovation.
Previously she was a postdoc with Kira Poskanzer at the University of California, San Francisco (UCSF), USA, where she studied how astrocytes sense dopamine in the cerebral cortex. She received a Horizon 2020 Marie Skłodowska-Curie Actions Global Fellowship to develop her project at UCSF and the Max Delbrück Center (MDC) in Berlin, Germany. Silvia did her PhD with Pau Gorostiza at IBEC working on photopharmacology of metabotropic glutamate receptors for precision medicine approaches. She has a Bachelor in Biotechnology and a Master in Neuroscience from the University of Trieste, Italy.
Silvia's research will focus on using all-optical tools to image brain activity ex vivo and in vivo, to unveil how the different building blocks of the brain—neurotransmitters and modulators and their receptors, and different cell types across brain regions—interact in contributing to normal brain function and disease. Her ultimate goal is to develop personalized therapeutic strategies for neuropsychiatric conditions.Staff member publications
Pittolo, Silvia, Lee, Hyojung, Lladó, Anna, Tosi, Sébastien, Bosch, Miquel, Bardia, Lídia, Gómez-Santacana, Xavier, Llebaria, Amadeu, Soriano, Eduardo, Colombelli, Julien, Poskanzer, Kira E., Perea, Gertrudis, Gorostiza, Pau, (2019). Reversible silencing of endogenous receptors in intact brain tissue using two-photon pharmacology Proceedings of the National Academy of Sciences of the United States of America 116, (27), 13680-13689
The physiological activity of proteins is often studied with loss-of-function genetic approaches, but the corresponding phenotypes develop slowly and can be confounding. Photopharmacology allows direct, fast, and reversible control of endogenous protein activity, with spatiotemporal resolution set by the illumination method. Here, we combine a photoswitchable allosteric modulator (alloswitch) and 2-photon excitation using pulsed near-infrared lasers to reversibly silence metabotropic glutamate 5 (mGlu5) receptor activity in intact brain tissue. Endogenous receptors can be photoactivated in neurons and astrocytes with pharmacological selectivity and with an axial resolution between 5 and 10 µm. Thus, 2-photon pharmacology using alloswitch allows investigating mGlu5-dependent processes in wild-type animals, including synaptic formation and plasticity, and signaling pathways from intracellular organelles.
JTD Keywords: Photopharmacology, Photoactivation, Pharmacological selectivity, Functional silencing, 2-photon pharmacology
Gómez-Santacana, Xavier, Pittolo, Silvia, Rovira, Xavier, Lopez, Marc, Zussy, Charleine, Dalton, James A. R., Faucherre, Adèle, Jopling, Chris, Pin, Jean-Philippe, Ciruela, Francisco, Goudet, Cyril, Giraldo, Jesús, Gorostiza, Pau, Llebaria, Amadeu, (2017). Illuminating phenylazopyridines to photoswitch metabotropic glutamate receptors: From the flask to the animals 
ACS Central Science , 3, (1), 81-91 
Phenylazopyridines are photoisomerizable compounds with high potential to control biological functions with light. We have obtained a series of phenylazopyridines with light dependent activity as negative allosteric modulators (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5). Here we describe the factors needed to achieve an operational molecular photoisomerization and its effective translation into in vitro and in vivo receptor photoswitching, which includes zebrafish larva motility and the regulation of the antinociceptive effects in mice. The combination of light and some specific phenylazopyridine ligands displays atypical pharmacological profiles, including light-dependent receptor overactivation, which can be observed both in vitro and in vivo. Remarkably, the localized administration of light and a photoswitchable compound in the peripheral tissues of rodents or in the brain amygdalae results in an illumination-dependent analgesic effect. The results reveal a robust translation of the phenylazopyridine photoisomerization to a precise photoregulation of biological activity.
JTD
Rovira, Xavier, Trapero, Ana, Pittolo, Silvia, Zussy, Charleine, Faucherre, Adèle, Jopling, Chris, Giraldo, Jesús, Pin, Jean-Philippe, Gorostiza, Pau, Goudet, Cyril, Llebaria, Amadeu, (2016). OptoGluNAM4.1, a Photoswitchable allosteric antagonist for real-time control of mGlu4 receptor activity Cell Chemical Biology 23, (8), 929-934
OptoGluNAM4.1, a negative allosteric modulator (NAM) of metabotropic glutamate receptor 4 (mGlu4) contains a reactive group that covalently binds to the receptor and a blue-light-activated, fast-relaxing azobenzene group that allows reversible receptor activity photocontrol in vitro and in vivo. OptoGluNAM4.1 induces light-dependent behavior in zebrafish and reverses the activity of the mGlu4 agonist LSP4-2022 in a mice model of chronic pain, defining a photopharmacological tool to better elucidate the physiological roles of the mGlu4 receptor in the nervous system.
JTD
Izquierdo-Serra, M., Bautista-Barrufet, A., Trapero, A., Garrido-Charles, A., Diaz-Tahoces, A., Camarero, N., Pittolo, S., Valbuena, S., Perez-Jimenez, A., Gay, M., Garcia-Moll, A., Rodriguez-Escrich, C., Lerma, J., De La Villa, P., Fernandez, E., Pericas, M. A., Llebaria, A., Gorostiza, P., (2016). Optical control of endogenous receptors and cellular excitability using targeted covalent photoswitches Nature Communications 7, 12221
Light-regulated drugs allow remotely photoswitching biological activity and enable plausible therapies based on small molecules. However, only freely diffusible photochromic ligands have been shown to work directly in endogenous receptors and methods for covalent attachment depend on genetic manipulation. Here we introduce a chemical strategy to covalently conjugate and photoswitch the activity of endogenous proteins and demonstrate its application to the kainate receptor channel GluK1. The approach is based on photoswitchable ligands containing a short-lived, highly reactive anchoring group that is targeted at the protein of interest by ligand affinity. These targeted covalent photoswitches (TCPs) constitute a new class of light-regulated drugs and act as prosthetic molecules that photocontrol the activity of GluK1-expressing neurons, and restore photoresponses in degenerated retina. The modularity of TCPs enables the application to different ligands and opens the way to new therapeutic opportunities.
JTD
A. R. Dalton, J., Lans, I., Rovira, X., Malhaire, F., Gómez-Santacana, X., Pittolo, S., Gorostiza, P., Llebaria, A., Goudet, C., Pin, J-P., Giraldo, J., (2016). Shining light on an mGlu5 photoswitchable NAM: A theoretical perspective Current Neuropharmacology , 14, (5), 441-454
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
Gascón-Moya, Marta, Pejoan, Arnau, Izquierdo-Serra, M., Pittolo, Silvia, Cabrè, Gisela, Hernando, Jordi, Alibés, Ramon, Gorostiza, Pau, Busque, Felix, (2015). An optimized glutamate receptor photoswitch with sensitized azobenzene isomerization Journal of Organic Chemistry 80, (20), 9915-9925
A new azobenzene-based photoswitch, 2, has been designed to enable optical control of ionotropic glutamate receptors in neurons via sensitized two-photon excitation with NIR light. In order to develop an efficient and versatile synthetic route for this molecule, a modular strategy is described which relies on the use of a new linear fully protected glutamate derivative stable in basic media. The resulting compound undergoes one-photon trans-cis photoisomerization via two different mechanisms: direct excitation of its azoaromatic unit, and irradiation of the pyrene sensitizer, a well known two-photon sensitive chromophore. Moreover, 2 presents large thermal stability of its cis isomer, in contrast to other two-photon responsive switches relying on the intrinsic non-linear optical properties of push-pull substituted azobenzenes. As a result, the molecular system developed herein is a very promising candidate for evoking large photoinduced biological responses during the multiphoton operation of neuronal glutamate receptors with NIR light, which require accumulation of the protein-bound cis state of the switch upon repeated illumination.
A new azobenzene-based photoswitch, 2, has been designed to enable optical control of ionotropic glutamate receptors in neurons via sensitized two-photon excitation with NIR light. In order to develop an efficient and versatile synthetic route for this molecule, a modular strategy is described which relies on the use of a new linear fully protected glutamate derivative stable in basic media. The resulting compound undergoes one-photon trans-cis photoisomerization via two different mechanisms: direct excitation of its azoaromatic unit, and irradiation of the pyrene sensitizer, a well known two-photon sensitive chromophore. Moreover, 2 presents large thermal stability of its cis isomer, in contrast to other two-photon responsive switches relying on the intrinsic non-linear optical properties of push-pull substituted azobenzenes. As a result, the molecular system developed herein is a very promising candidate for evoking large photoinduced biological responses during the multiphoton operation of neuronal glutamate receptors with NIR light, which require accumulation of the protein-bound cis state of the switch upon repeated illumination.
JTD
Pittolo, Silvia, Gómez-Santacana, Xavier, Eckelt, Kay, Rovira, Xavier, Dalton, James, Goudet, Cyril, Pin, Jean-Philippe, Llobet, Artur, Giraldo, Jesús, Llebaria, Amadeu, Gorostiza, Pau, (2014). An allosteric modulator to control endogenous G protein-coupled receptors with light Nature Chemical Biology , 10, (10), 813-815
Controlling drug activity with light offers the possibility of enhancing pharmacological selectivity with spatial and temporal regulation, thus enabling highly localized therapeutic effects and precise dosing patterns. Here we report on the development and characterization of what is to our knowledge the first photoswitchable allosteric modulator of a G protein–coupled receptor. Alloswitch-1 is selective for the metabotropic glutamate receptor mGlu5 and enables the optical control of endogenous mGlu5 receptors.
JTD
Izquierdo-Serra, M., Gascón-Moya, Marta, Hirtz, Jan J., Pittolo, Silvia, Poskanzer, Kira E., Ferrer, Eric, Alibés, Ramon, Busque, Felix, Yuste, Rafael, Hernando, Jordi, Gorostiza, Pau, (2014). Two-photon neuronal and astrocytic stimulation of azobenzene-based photoswitches Journal of the American Chemical Society American Chemical Society 136, (24), 8693-8701
Synthetic photochromic compounds can be designed to control a variety of proteins and their biochemical functions in living cells, but the high spatiotemporal precision and tissue penetration of two-photon stimulation has never been investigated in these molecules. Here we demonstrate two-photon excitation of azobenzene-based protein switches, and versatile strategies to enhance their photochemical responses. This enables new applications to control the activation of neurons and astrocytes with cellular and subcellular resolution.
JTD
