RT Journal Article
SR Electronic
T1 The Residence Time of GABA<sub>A</sub>Rs at Inhibitory Synapses Is Determined by Direct Binding of the Receptor α1 Subunit to Gephyrin
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 14677
OP 14687
DO 10.1523/JNEUROSCI.2001-11.2011
VO 31
IS 41
A1 Mukherjee, Jayanta
A1 Kretschmannova, Karla
A1 Gouzer, Geraldine
A1 Maric, Hans-Michael
A1 Ramsden, Sarah
A1 Tretter, Verena
A1 Harvey, Kirsten
A1 Davies, Paul A.
A1 Triller, Antoine
A1 Schindelin, Hermann
A1 Moss, Stephen J.
YR 2011
UL http://www.jneurosci.org/content/31/41/14677.abstract
AB The majority of fast synaptic inhibition in the brain is mediated by benzodiazepine-sensitive α1-subunit-containing GABA type A receptors (GABAARs); however, our knowledge of the mechanisms neurons use to regulate their synaptic accumulation is rudimentary. Using immunoprecipitation, we demonstrate that GABAARs and gephyrin are intimately associated at inhibitory synapses in cultured rat neurons. In vitro we reveal that the E-domain of gephyrin directly binds to the α1 subunit with an affinity of ∼20 μm, mediated by residues 360–375 within the intracellular domain of this receptor subunit. Mutating residues 360–375 decreases both the accumulation of α1-containing GABAARs at gephyrin-positive inhibitory synapses in hippocampal neurons and the amplitude of mIPSCs. We also demonstrate that the affinity of gephyrin for the α1 subunit is modulated by Thr375, a putative phosphorylation site. Mutation of Thr375 to a phosphomimetic, negatively charged amino acid decreases both the affinity of the α1 subunit for gephyrin, and therefore receptor accumulation at synapses, and the amplitude of mIPSCs. Finally, single-particle tracking reveals that gephyrin reduces the diffusion of α1-subunit-containing GABAARs specifically at inhibitory synapses, thereby increasing their confinement at these structures. Our results suggest that the direct binding of gephyrin to residues 360–375 of the α1 subunit and its modulation are likely to be important determinants for the stabilization of GABAARs at synaptic sites, thereby modulating the strength of synaptic inhibition.