Format

Send to

Choose Destination
EMBO J. 2015 Nov 3;34(21):2686-702. doi: 10.15252/embj.201591885. Epub 2015 Oct 7.

Disruption of adaptor protein 2μ (AP-2μ) in cochlear hair cells impairs vesicle reloading of synaptic release sites and hearing.

Author information

1
Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
2
Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin, Germany NeuroCure Cluster of Excellence & Collaborative Research Center 958, Freie Universität Berlin, Berlin, Germany.
3
Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.
4
Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Auditory Systems Physiology Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany.
5
Bernstein Group Biophysics of Neural Computation, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany andreas@nld.ds.mpg.de haucke@fmp-berlin.de tmoser@gwdg.de.
6
Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany.
7
Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Molecular Structural Biology, Institute for Microbiology and Genetics, University of Göttingen, Göttingen, Germany.
8
Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.
9
Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.
10
Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin, Germany.
11
Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.
12
Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Molecular Biology of Cochlear Neurotransmission Group, InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany.
13
Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany.
14
Leibniz Institut für Molekulare Pharmakologie (FMP), Berlin, Germany NeuroCure Cluster of Excellence & Collaborative Research Center 958, Freie Universität Berlin, Berlin, Germany andreas@nld.ds.mpg.de haucke@fmp-berlin.de tmoser@gwdg.de.
15
Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany Collaborative Research Center 889, University of Göttingen, Göttingen, Germany Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany andreas@nld.ds.mpg.de haucke@fmp-berlin.de tmoser@gwdg.de.

Abstract

Active zones (AZs) of inner hair cells (IHCs) indefatigably release hundreds of vesicles per second, requiring each release site to reload vesicles at tens per second. Here, we report that the endocytic adaptor protein 2μ (AP-2μ) is required for release site replenishment and hearing. We show that hair cell-specific disruption of AP-2μ slows IHC exocytosis immediately after fusion of the readily releasable pool of vesicles, despite normal abundance of membrane-proximal vesicles and intact endocytic membrane retrieval. Sound-driven postsynaptic spiking was reduced in a use-dependent manner, and the altered interspike interval statistics suggested a slowed reloading of release sites. Sustained strong stimulation led to accumulation of endosome-like vacuoles, fewer clathrin-coated endocytic intermediates, and vesicle depletion of the membrane-distal synaptic ribbon in AP-2μ-deficient IHCs, indicating a further role of AP-2μ in clathrin-dependent vesicle reformation on a timescale of many seconds. Finally, we show that AP-2 sorts its IHC-cargo otoferlin. We propose that binding of AP-2 to otoferlin facilitates replenishment of release sites, for example, via speeding AZ clearance of exocytosed material, in addition to a role of AP-2 in synaptic vesicle reformation.

KEYWORDS:

active zone; endocytosis; release site clearance; synaptic ribbon; vesicle reformation

PMID:
26446278
PMCID:
PMC4641533
DOI:
10.15252/embj.201591885
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center