Tryptophan-rich basic protein (WRB) mediates insertion of the tail-anchored protein otoferlin and is required for hair cell exocytosis and hearing

Christian Vogl, Iliana Panou, Gulnara Yamanbaeva, Carolin Wichmann, Sara J. Mangosing, Fabio Vilardi, Artur A. Indzhykulian, Tina Pangršič, Rosamaria Santarelli, Montserrat Rodriguez-Ballesteros, Thomas Weber, Sangyong Jung, Elena Cardenas, Xudong Wu, Sonja M. Wojcik, Kelvin Kwan, Ignacio del Castillo, Blanche Schwappach, Nicola Strenzke, David P. CoreyShuh Yow Lin, Tobias Moser

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The transmembrane recognition complex (TRC40) 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 TRC40 pathway. We mutated the TRC40 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 (IHCs) displayed normal numbers of afferent synapses, Ca2+ channels, and membrane-proximal vesicles, but contained fewer ribbon-associated vesicles. Patch-clamp of IHCs 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 TRC40 pathway is critical for hearing and propose that otoferlin is an essential substrate of this pathway in hair cells.

Original languageEnglish (US)
Pages (from-to)2536-2552
Number of pages17
JournalEMBO Journal
Volume35
Issue number23
DOIs
StatePublished - Dec 1 2016

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Molecular Biology
  • Neuroscience(all)

Keywords

  • deafness
  • endoplasmic reticulum
  • protein targeting
  • synapse
  • tail-anchored protein

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    Vogl, C., Panou, I., Yamanbaeva, G., Wichmann, C., Mangosing, S. J., Vilardi, F., Indzhykulian, A. A., Pangršič, T., Santarelli, R., Rodriguez-Ballesteros, M., Weber, T., Jung, S., Cardenas, E., Wu, X., Wojcik, S. M., Kwan, K., del Castillo, I., Schwappach, B., Strenzke, N., ... Moser, T. (2016). Tryptophan-rich basic protein (WRB) mediates insertion of the tail-anchored protein otoferlin and is required for hair cell exocytosis and hearing. EMBO Journal, 35(23), 2536-2552. https://doi.org/10.15252/embj.201593565