Otoferlin acts as a Ca2+ sensor for vesicle fusion and vesicle pool replenishment at auditory hair cell ribbon synapses
- Institut Pasteur, France
- Universidad de Buenos Aires, Argentina
- Yale University School of Medicine, United States
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), France
- Université Paris Descartes, Sorbonne Paris Cité, France
- Texas Tech University Health Sciences Center, United States
- Université d'Auvergne, France
Abstract
Hearing relies on rapid, temporally precise, and sustained neurotransmitter release at the ribbon synapses of sensory cells, the inner hair cells (IHCs). This process requires otoferlin, a six C2-domain, Ca2+-binding transmembrane protein of synaptic vesicles. To decipher the role of otoferlin in the synaptic vesicle cycle, we produced knock-in mice (OtofAla515,Ala517/Ala515,Ala517) with lower Ca2+-binding affinity of the C2C domain. The IHC ribbon synapse structure, synaptic Ca2+ currents, and otoferlin distribution were unaffected in these mutant mice, but auditory brainstem response wave-I amplitude was reduced. Lower Ca2+ sensitivity and delay of the fast and sustained components of synaptic exocytosis were revealed by membrane capacitance measurement upon modulations of intracellular Ca2+ concentration, by varying Ca2+ influx through voltage-gated Ca2+-channels or Ca2+ uncaging. Otoferlin thus functions as a Ca2+ sensor, setting the rates of primed vesicle fusion with the presynaptic plasma membrane and synaptic vesicle pool replenishment in the IHC active zone.
Article and author information
Author details
Shyam S Krishnakumar
Funding
Foundation Raymonde et Guy Strittmatter (Research project grant)
- Christine Petit
Foundation BNP Parisbas (Research project grant)
- Christine Petit
LHW-Stiftung (Research project grant)
- Christine Petit
LabExLifesenses (ANR‐10‐LABX‐65)
- Christine Petit
Investissements d'Avenir (ANR‐11‐IDEX‐0004‐02)
- Christine Petit
Agir pour l'Audition (Prix Emergence scientifique)
- Nicolas Antoine Michalski
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal experiments were carried out in accordance with European Community Council Directive 2010/63/UE under authorizations 2012-028, 2012-038, and 2014-005 from the Institut Pasteur ethics committee for animal experimentation.
Copyright
© 2017, Michalski et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 3,445
- views
-
- 634
- downloads
-
- 108
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Otoferlin acts as a Ca2+ sensor for vesicle fusion and vesicle pool replenishment at auditory hair cell ribbon synapses
eLife 6:e31013.
https://doi.org/10.7554/eLife.31013
