NGL-2 Deletion Leads to Autistic-like Behaviors Responsive to NMDAR Modulation

Abstract

NGL-2 is a postsynaptic adhesion molecule known to regulate synaptic transmission, but whether NGL-2 regulates synaptic plasticity and specific behaviors remains unknown. Um et al. find that mice lacking NGL-2 display suppressed NMDA receptor-dependent synaptic plasticity and autistic-like social deficits and repetitive behaviors that are responsive to NMDA receptor activation.Netrin-G ligand 2 (NGL-2)/LRRC4, implicated in autism spectrum disorders and schizophrenia, is a leucine-rich repeat-containing postsynaptic adhesion molecule that interacts intracellularly with the excitatory postsynaptic scaffolding protein PSD-95 and trans-synaptically with the presynaptic adhesion molecule netrin-G2. Functionally, NGL-2 regulates excitatory synapse development and synaptic transmission. However, whether it regulates synaptic plasticity and disease-related specific behaviors is not known. Here, we report that mice lacking NGL-2 (Lrrc4−/− mice) show suppressed N-Methyl-D-aspartate receptor (NMDAR)-dependent synaptic plasticity in the hippocampus. NGL-2 associates with NMDARs through both PSD-95-dependent and -independent mechanisms. Moreover, Lrrc4−/− mice display mild social interaction deficits and repetitive behaviors that are rapidly improved by pharmacological NMDAR activation. These results suggest that NGL-2 promotes synaptic stabilization of NMDARs, regulates NMDAR-dependent synaptic plasticity, and prevents autistic-like behaviors from developing in mice, supporting the hypothesis that NMDAR dysfunction contributes to autism spectrum disorders. © 2018 The Author(s)