Neuroligin 3 Splice Isoforms Shape Mouse Hippocampal Inhibitory Synaptic Function

Synapse formation is a dynamic process essential for neuronal circuit development and maturation. At the synaptic cleft, trans-synaptic protein-protein interactions constitute major biological determinants of proper synapse efficacy. The balance of excitatory and inhibitory synaptic transmission (E-I balance) stabilizes synaptic activity and its dysregulation has been implicated in neurodevelopmental disorders including autism spectrum disorders. However, the molecular mechanisms underlying E-I balance remains to be elucidated. Here, we investigate Neuroligin (Nlgn) genes which encode a family of postsynaptic adhesion molecules that shape excitatory and inhibitory synaptic function. We identified that NLGN3 protein differentially regulates inhibitory synaptic transmission in a splice isoform-dependent manner in hippocampal CA1 synapses. Distinct subcellular localization patterns of NLGN3 isoforms contribute to the functional differences observed among splice variants. Finally, our single-cell sequencing analysis reveals that Nlgn1 and Nlgn3 are the major Nlgn genes and that Nlgn splice isoforms are highly diverse in CA1 pyramidal neurons. Overall design: The cytosol of single cell CA1 neuron was harvested using the whole cell patch-clamp technique