title: Hair cell synaptic ribbons are essential for synchronous auditory signalling.
abstract: Hearing relies on faithful synaptic transmission at the ribbon synapse of cochlear inner hair cells (IHCs). At present, the function of presynaptic ribbons at these synapses is still largely unknown. Here we show that anchoring of IHC ribbons is impaired in mouse mutants for the presynaptic scaffolding protein Bassoon. The lack of active-zone-anchored synaptic ribbons reduced the presynaptic readily releasable vesicle pool, and impaired synchronous auditory signalling as revealed by recordings of exocytic IHC capacitance changes and sound-evoked activation of spiral ganglion neurons. Both exocytosis of the hair cell releasable vesicle pool and the number of synchronously activated spiral ganglion neurons co-varied with the number of anchored ribbons during development. Interestingly, ribbon-deficient IHCs were still capable of sustained exocytosis with normal Ca2+-dependence. Endocytic membrane retrieval was intact, but an accumulation of tubular and cisternal membrane profiles was observed in ribbon-deficient IHCs. We conclude that ribbon-dependent synchronous release of multiple vesicles at the hair cell afferent synapse is essential for normal hearing.
authors.affiliation: Department of Otolaryngology and Center for Molecular Physiology of the Brain, University of Goettingen, 37099 Goettingen, Germany.
authors.forename: Darina
authors.initials: D
authors.lastname: Khimich
authors.forename: Régis
authors.initials: R
authors.lastname: Nouvian
authors.forename: Rémy
authors.initials: R
authors.lastname: Pujol
authors.forename: Susanne
authors.initials: S
authors.lastname: Tom Dieck
authors.forename: Alexander
authors.initials: A
authors.lastname: Egner
authors.forename: Eckart D
authors.initials: ED
authors.lastname: Gundelfinger
authors.forename: Tobias
authors.initials: T
authors.lastname: Moser
mesh_terms: D000200:Action Potentials; D000818:Animals; D001306:Auditory Pathways / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D003051:Cochlea / Q000166:cytology; D004705:Endocytosis; D005089:Exocytosis; D006199:Hair Cells, Auditory, Inner / Q000166:cytology* / Q000502:physiology*; D006309:Hearing / Q000502:physiology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: C498441:Bsn protein, mouse; D009419:Nerve Tissue Proteins; D002118:Calcium