The Autism-Related Protein PX-RICS Mediates GABAergic Synaptic Plasticity in Hippocampal Neurons and Emotional Learning in Mice

GABAergic dysfunction underlies many neurodevelopmental and psychiatric disorders. GABAergic synapses exhibit several forms of plasticity at both pre- and postsynaptic levels. NMDA receptor (NMDAR)-dependent inhibitory long-term potentiation (iLTP) at GABAergic postsynapses requires an increase in surface GABA(A)Rs through promoted exocytosis, however, the regulatory mechanisms and the neuropathological significance remain unclear. Here we report that the autism-related protein PX-RICS is involved in GABA(A)R transport driven during NMDAR-dependent GABAergic iLTP. Chemically induced iLTP elicited a rapid increase in surface GABA(A)Rs in wild-type mouse hippocampal neurons, but not in PX-RICS/RIC'S-cleficient neurons. This increase in surface GABAARs required the PX-RICS/GABARAP/14-3-3 complex, as revealed by gene knockdown and rescue studies. iLTP induced CaMKII-dependent phosphorylation of PX-RICS to promote PX-RICS-14-3-3 assembly. Notably, PX-RICS/RICS-deficient mice showed impaired amygdala-clepenclent fear leaming, which was ameliorated by potentiating GABAergic activity with clonazepam. Our results suggest that PX-RICS-mecliated GABA(A)R trafficking is a key target for GABAergic plasticity and its dysfunction leads to atypical emotional processing underlying autism. (C) 2018 The Authors. Published by Elsevier B.V.