Synaptic Recruitment of Gephyrin Regulates Surface GABAA Receptor Dynamics for the Expression of Inhibitory LTP

Nat Commun. 2014 Jun 4;5:3921. doi: 10.1038/ncomms4921.

Abstract

Postsynaptic long-term potentiation of inhibition (iLTP) can rely on increased GABAA receptors (GABA(A)Rs) at synapses by promoted exocytosis. However, the molecular mechanisms that enhance the clustering of postsynaptic GABA(A)Rs during iLTP remain obscure. Here we demonstrate that during chemically induced iLTP (chem-iLTP), GABA(A)Rs are immobilized and confined at synapses, as revealed by single-particle tracking of individual GABA(A)Rs in cultured hippocampal neurons. Chem-iLTP expression requires synaptic recruitment of the scaffold protein gephyrin from extrasynaptic areas, which in turn is promoted by CaMKII-dependent phosphorylation of GABA(A)R-β3-Ser(383). Impairment of gephyrin assembly prevents chem-iLTP and, in parallel, blocks the accumulation and immobilization of GABA(A)Rs at synapses. Importantly, an increase of gephyrin and GABA(A)R similar to those observed during chem-iLTP in cultures were found in the rat visual cortex following an experience-dependent plasticity protocol that potentiates inhibitory transmission in vivo. Thus, phospho-GABA(A)R-β3-dependent accumulation of gephyrin at synapses and receptor immobilization are crucial for iLTP expression and are likely to modulate network excitability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism*
  • Carrier Proteins / metabolism*
  • Cells, Cultured
  • Hippocampus / cytology
  • Long-Term Potentiation / physiology*
  • Membrane Proteins / metabolism*
  • Mice
  • Neural Inhibition / physiology
  • Neurons / metabolism*
  • Phosphorylation
  • Rats
  • Receptors, GABA-A / metabolism*
  • Receptors, N-Methyl-D-Aspartate
  • Visual Cortex / metabolism*

Substances

  • Carrier Proteins
  • Gabrb3 protein, mouse
  • Gabrb3 protein, rat
  • Membrane Proteins
  • Receptors, GABA-A
  • Receptors, N-Methyl-D-Aspartate
  • gephyrin
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2