Tryptophan-rich basic protein (WRB) mediates insertion of the tail-anchored protein otoferlin and is required for hair cell exocytosis and hearing
Journal
The EMBO journal
Journal Volume
35
Journal Issue
23
Pages
2536-2552
Date Issued
2016
Author(s)
Vogl, Christian
Panou, Iliana
Yamanbaeva, Gulnara
Wichmann, Carolin
Mangosing, Sara J.
Vilardi, Fabio
Indzhykulian, Artur A.
Pangr?i?, Tina
Santarelli, Rosamaria
Rodriguez-Ballesteros, Montserrat
Weber, Thomas
Jung, Sangyong
Cardenas, Elena
Wu, Xudong
Wojcik, Sonja M.
Kwan, Kelvin Y.
Del Castillo, Ignacio
Schwappach, Blanche
Strenzke, Nicola
Corey, David P.
Moser, Tobias
Abstract
Abstract The transmembrane recognition complex ( TRC 40) pathway mediates the insertion of tail‐anchored ( TA ) proteins into membranes. Here, we demonstrate that otoferlin, a TA protein essential for hair cell exocytosis, is inserted into the endoplasmic reticulum ( ER ) via the TRC 40 pathway. We mutated the TRC 40 receptor tryptophan‐rich basic protein (Wrb) in hair cells of zebrafish and mice and studied the impact of defective TA protein insertion. Wrb disruption reduced otoferlin levels in hair cells and impaired hearing, which could be restored in zebrafish by transgenic Wrb rescue and otoferlin overexpression. Wrb‐deficient mouse inner hair cells ( IHC s) displayed normal numbers of afferent synapses, Ca 2+ channels, and membrane‐proximal vesicles, but contained fewer ribbon‐associated vesicles. Patch‐clamp of IHC s revealed impaired synaptic vesicle replenishment. In vivo recordings from postsynaptic spiral ganglion neurons showed a use‐dependent reduction in sound‐evoked spiking, corroborating the notion of impaired IHC vesicle replenishment. A human mutation affecting the transmembrane domain of otoferlin impaired its ER targeting and caused an auditory synaptopathy. We conclude that the TRC 40 pathway is critical for hearing and propose that otoferlin is an essential substrate of this pathway in hair cells.
SDGs
Type
journal article