title: Association of gephyrin with synaptic and extrasynaptic GABAA receptors varies during development in cultured hippocampal neurons.
abstract: Several studies have reported extrasynaptic clusters of GABAA receptors in hippocampal neurons. Yet their functional relevance as well as their evolution in relation with gephyrin during synaptogenesis remain unknown. We have analyzed the expression pattern of the main proteins of the GABAergic synapses during synaptogenesis in cultured hippocampal neurons. We found that GABAergic terminals, characterized by VIAAT and GAD-65 expression, differentiated 3 to 7 days after the glutamatergic endings. At the postsynaptic side, the GABAAR- beta3 subunit was first diffuse and then clustered when GABAergic terminals differentiated and gephyrin formed large clusters. Colocalization of these proteins was high and increased with development. At later stages, GABAAR beta3 clusters colocalized with gephyrin at synaptic but also at extrasynaptic sites. GABAAR gamma2 subunits were directly expressed as clusters which were first extrasynaptic and not associated with gephyrin. Subsequently, the GABAAR gamma2 subunits associated with gephyrin at synaptic and/or extrasynaptic sites. Our data indicate that formation of GABAAR gamma2 subunit clusters is gephyrin independent.
authors.affiliation: Laboratoire de Biologie Cellulaire de la Synapse Normale et Pathologique, Institut National de la Santé et de la Recherche Médicale U497, Ecole Normale Supérieure, 75005, Paris, France.
authors.forename: Lydia
authors.initials: L
authors.lastname: Danglot
authors.forename: Antoine
authors.initials: A
authors.lastname: Triller
authors.forename: Alain
authors.initials: A
authors.lastname: Bessis
mesh_terms: D026905:Amino Acid Transport Systems; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D005333:Fetus; D005968:Glutamate Decarboxylase / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D009433:Neural Inhibition / Q000502:physiology; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism*; D013570:Synaptic Membranes / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D033921:Vesicular Transport Proteins; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D026905:Amino Acid Transport Systems; D002352:Carrier Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D021122:Protein Subunits; D011963:Receptors, GABA-A; C118623:Slc32a1 protein, rat; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D033921:Vesicular Transport Proteins; C073441:gephyrin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2