Nanoscale Molecular Reorganization of the Inhibitory Postsynaptic Density Is a Determinant of GABAergic Synaptic Potentiation

Abstract

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.

Characterization of Visual Object Representations in Rat Primary Visual Cortex

“…Specifically, in this study, we applied for the first time the Dominant Set [16] clustering algorithm (DS) to understand the structure of visual object representations in a visual cortical area. The choice of the DS has been driven also by it recent success in related fields, like in brain connectomic [5,6] or neuroscience [17], making it a good candidate for the task at hand. Furthermore, we applied an array of supervised algorithms to show that V1 neuronal responses can be used to predict with great accuracy the photometric information on the scene presented to the rat.…”

NMDA Receptor Autoantibodies in Autoimmune Encephalitis Cause a Subunit-Specific Nanoscale Redistribution of NMDA Receptors

“…Yet the time course of the changes of NMDAR distribution that take place at the synaptic level is unknown. Studies have shown that the nanoscale distribution and mobility of synaptic receptors, including NMDARs, are critical for normal neurotransmission (Dupuis et al, 2014; MacGillavry et al, 2013; Nair et al, 2013; Pennacchietti et al, 2017; Specht et al, 2013). Therefore, we reasoned that an antibody-mediated disruption of the NMDAR should also alter the nanoscale distribution of these receptors and synaptic function.…”

Adaptive-illumination STED nanoscopy

“…We further focused on other cellular compartments that benefit from superresolution microscopy due to their small sizes, namely synapses (14). In particular, we focused on gephyrin, a scaffolding protein of inhibitory synapses that exhibits a monocluster or multicluster organization (15)(16)(17). Here, we used our pixelwise three-step DyMIN process to automatically prelocalize the structure twice with low resolution and low STED powers in each pixel, followed by a local recording at full resolution.…”