Disruption of postsynaptic GABAA receptor clusters leads to decreased GABAergic innervation of pyramidal neurons (original) (raw)

We have used RNA interference (RNAi) to knock down the expression of the c2 subunit of the GABA A receptors (GABA A Rs) in pyramidal neurons in culture and in the intact brain. Two hairpin small interference RNAs (shRNAs) for the c2 subunit, one targeting the coding region and the other one the 3¢-untranslated region (UTR) of the c2 mRNA, when introduced into cultured rat hippocampal pyramidal neurons, efficiently inhibited the synthesis of the GABA A receptor c2 subunit and the clustering of other GABA A R subunits and gephyrin in these cells. More significantly, this effect was accompanied by a reduction of the GABAergic innervation that these neurons received. In contrast, the c2 shRNAs had no effect on the clustering of postsynaptic a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, postsynaptic density protein 95 (PSD-95) or presynaptic glutamatergic innervation. A c2-enhanced green fluorescent protein (EGFP) subunit construct, whose mRNA did not contain the 3¢-UTR targeted by c2 RNAi, rescued both the postsynaptic clustering of GABA A Rs and the GABAergic innervation. Decreased GABA A R clustering and GABAergic innervation of pyramidal neurons in the post-natal rat cerebral cortex was also observed after in utero transfection of these neurons with the c2 shRNAs. The results indicate that the postsynaptic clustering of GABA A Rs in pyramidal neurons is involved in the stabilization of the presynaptic GABAergic contacts. 1 These authors contributed equally to this work.