Pennacchietti F Vascon S Nieus T Rosillo C Das S Tyagarajan SK Diaspro A Del Bue A Petrini EM Barberis A Cella Zanacchi F 2017 Gephyrin is a key scaffold protein mediating the anchoring of GABAA receptors at inhibitory synapses. Here, we exploited superresolution techniques combined with proximity-based clustering analysis and model simulations to investigate the single-molecule gephyrin reorganization during plasticity of inhibitory synapses in mouse hippocampal cultured neurons. This approach revealed that, during the expression of inhibitory LTP, the increase of gephyrin density at postsynaptic sites is associated with the promoted formation of gephyrin nanodomains. We demonstrate that the gephyrin rearrangement in nanodomains stabilizes the amplitude of postsynaptic currents, indicating that, in addition to the number of synaptic GABAA receptors, the nanoscale distribution of GABAA receptors in the postsynaptic area is a crucial determinant for the expression of inhibitory synaptic plasticity. In addition, the methodology implemented here clears the way to the application of the graph-based theory to single-molecule data for the description and quantification of the spatial organization of the synapse at the single-molecule level.SIGNIFICANCE STATEMENT The mechanisms of inhibitory synaptic plasticity are poorly understood, mainly because the size of the synapse is below the diffraction limit, thus reducing the effectiveness of conventional optical and imaging techniques. Here, we exploited superresolution approaches combined with clustering analysis to study at unprecedented resolution the distribution of the inhibitory scaffold protein gephyrin in response to protocols inducing LTP of inhibitory synaptic responses (iLTP). We found that, during the expression of iLTP, the increase of synaptic gephyrin is associated with the fragmentation of gephyrin in subsynaptic nanodomains. We demonstrate that such synaptic gephyrin nanodomains stabilize the amplitude of inhibitory postsynaptic responses, thus identifying the nanoscale gephyrin rearrangement as a key determinant for inhibitory synaptic plasticity. application/pdf https://sonar.ch/global/documents/21492 eng info:eu-repo/semantics/altIdentifier/doi/10.1523/JNEUROSCI.0514-16.2016 info:eu-repo/semantics/altIdentifier/pmid/28073939 info:eu-repo/semantics/openAccess The Journal of neuroscience : the official journal of the Society for Neuroscience. - 2017 GABAA receptors PALM STORM clustering gephyrin model simulations plasticity 6-Cyano-7-nitroquinoxaline-2,3-dione Algorithms Animals Carrier Proteins Cells, Cultured Computer Simulation Excitatory Amino Acid Agonists Excitatory Amino Acid Antagonists Female GABAergic Neurons Hippocampus Long-Term Synaptic Depression Male Membrane Proteins Mice Mice, Inbred C57BL Models, Neurological N-Methylaspartate Peptides Polymers Post-Synaptic Density Receptors, GABA-A Valine Nanoscale Molecular Reorganization of the Inhibitory Postsynaptic Density Is a Determinant of GABAergic Synaptic Potentiation. http://purl.org/coar/resource_type/c_6501