Tu_2015_Neuron_86_1407

Positioning type A GABA receptors (GABAARs) in front of GABA release sites sets the strength of inhibitory synapses. The evolutionarily conserved Ce-Punctin/MADD-4 is an anterograde synaptic organizer that specifies GABAergic versus cholinergic identity of postsynaptic domains at the C. elegans neuromuscular junctions (NMJs). Here we show that the Ce-Punctin secreted by GABAergic motor neurons controls the clustering of GABAARs through the synaptic adhesion molecule neuroligin (NLG-1) and the netrin receptor UNC-40/DCC. The short isoform of Ce-Punctin binds and clusters NLG-1 postsynaptically at GABAergic NMJs. NLG-1 disruption causes a strong reduction of GABAAR content at GABAergic synapses. Ce-Punctin also binds and localizes UNC-40 receptors in the postsynaptic membrane of NMJs, which promotes the recruitment of GABAARs by NLG-1. Since the mammalian orthologs of these genes are expressed in the central nervous system and their mutations are implicated in neuropsychiatric diseases, this molecular pathway might have been evolutionarily conserved.