Neurexins regulate presynaptic GABAB-receptors at central synapses
Fujun Luo, Alessandra Sclip, Sean A. Merrill, Thomas C. Südhof
Abstract
Abstract Diverse signaling complexes are precisely assembled at the presynaptic active zone for dynamic modulation of synaptic transmission and synaptic plasticity. Presynaptic GABA B -receptors nucleate critical signaling complexes regulating neurotransmitter release at most synapses. However, the molecular mechanisms underlying assembly of GABA B -receptor signaling complexes remain unclear. Here we show that neurexins are required for the localization and function of presynaptic GABA B -receptor signaling complexes. At four model synapses, excitatory calyx of Held synapses in the brainstem, excitatory and inhibitory synapses on hippocampal CA1-region pyramidal neurons, and inhibitory basket cell synapses in the cerebellum, deletion of neurexins rendered neurotransmitter release significantly less sensitive to GABA B -receptor activation. Moreover, deletion of neurexins caused a loss of GABA B -receptors from the presynaptic active zone of the calyx synapse. These findings extend the role of neurexins at the presynaptic active zone to enabling GABA B -receptor signaling, supporting the notion that neurexins function as central organizers of active zone signaling complexes.