Neurexins regulate presynaptic GABA<sub>B</sub>-receptors at central synapses.

Luo, Fujun; Sclip, Alessandra; Merrill, Sean; Südhof, Thomas C · Nat Commun · 2021

basic_science · Level V

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Abstract

Diverse signaling complexes are precisely assembled at the presynaptic active zone for dynamic modulation of synaptic transmission and synaptic plasticity. Presynaptic GABA<sub>B</sub>-receptors nucleate critical signaling complexes regulating neurotransmitter release at most synapses. However, the molecular mechanisms underlying assembly of GABA<sub>B</sub>-receptor signaling complexes remain unclear. Here we show that neurexins are required for the localization and function of presynaptic GABA<sub>B</sub>-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<sub>B</sub>-receptor activation. Moreover, deletion of neurexins caused a loss of GABA<sub>B</sub>-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<sub>B</sub>-receptor signaling, supporting the notion that neurexins function as central organizers of active zone signaling complexes.

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