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

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

  • EMBO J. 2016 Dec 1;35(23):2536-2552. doi: 10.15252/embj.201593565.
Christian Vogl 1 2,  Iliana Panou 1 2 3,  Gulnara Yamanbaeva 2 4,  Carolin Wichmann 2 5,  Sara J Mangosing 6,  Fabio Vilardi 7,  Artur A Indzhykulian 8,  Tina Pangršič 2 9,  Rosamaria Santarelli 10 11,  Montserrat Rodriguez-Ballesteros 12,  Thomas Weber 1,  Sangyong Jung 1 13,  Elena Cardenas 6,  Xudong Wu 8,  Sonja M Wojcik 14,  Kelvin Y Kwan 15,  Ignacio Del Castillo 12 16,  Blanche Schwappach 7,  Nicola Strenzke 2 4,  David P Corey 17,  Shuh-Yow Lin 18,  Tobias Moser 19 2 13 20
Affiliations

Affiliations

  • 1 Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.
  • 2 Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.
  • 3 Göttingen Graduate School for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany.
  • 4 Auditory Systems Physiology Group and InnerEarLab, Department of Otolaryngology, University of Göttingen Medical Center, Göttingen, Germany.
  • 5 Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.
  • 6 Otolaryngology Division, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA.
  • 7 Institute of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
  • 8 Howard Hughes Medical Institute and Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
  • 9 Synaptic Physiology of Mammalian Vestibular Hair Cells Junior Research Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.
  • 10 Department of Neurosciences, University of Padova, Padova, Italy.
  • 11 Audiology and Phoniatrics Service, Treviso Regional Hospital, Treviso, Italy.
  • 12 Servicio de Genetica, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain.
  • 13 Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
  • 14 Department of Molecular Neurobiology, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany.
  • 15 W. M. Keck Center for Collaborative Neuroscience, Nelson Lab-D250, Rutgers University, Piscataway, NJ, USA.
  • 16 Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.
  • 17 Howard Hughes Medical Institute and Department of Neurobiology, Harvard Medical School, Boston, MA, USA [email protected] [email protected] [email protected].
  • 18 Otolaryngology Division, Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA [email protected] [email protected] [email protected].
  • 19 Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany [email protected] [email protected] [email protected].
  • 20 Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany.
PMID: 27458190 DOI: 10.15252/embj.201593565
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.

Keywords

deafness; endoplasmic reticulum; protein targeting; synapse; tail‐anchored protein.

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