The presynaptic ribbon maintains vesicle populations at the hair cell afferent fiber synapse

Lars Becker, Michael E. Schnee, Mamiko Niwa, Willy Sun, Stephan Maxeiner, Sara Talaei, Bechara Kachar, Mark A. Rutherford, Anthony J. Ricci

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

The ribbon is the structural hallmark of cochlear inner hair cell (IHC) afferent synapses, yet its role in information transfer to spiral ganglion neurons (SGNs) remains unclear. We investigated the ribbon’s contribution to IHC synapse formation and function using KO mice lacking RIBEYE. Despite loss of the entire ribbon structure, synapses retained their spatiotemporal development and KO mice had a mild hearing deficit. IHCs of KO had fewer synaptic vesicles and reduced exocytosis in response to brief depolarization; a high stimulus level rescued exocytosis in KO. SGNs exhibited a lack of sustained excitatory postsynaptic currents (EPSCs). We observed larger postsynaptic glutamate receptor plaques, potentially compensating for the reduced EPSC rate in KO. Surprisingly, large-amplitude EPSCs were maintained in KO, while a small population of low-amplitude slower EPSCs was increased in number. The ribbon facilitates signal transduction at physiological stimulus levels by retaining a larger residency pool of synaptic vesicles.

Original languageEnglish
Article numbere30241
JournaleLife
Volume7
DOIs
StatePublished - Jan 12 2018

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