TY - JOUR T1 - Otoferlin Couples to Clathrin-Mediated Endocytosis in Mature Cochlear Inner Hair Cells JF - The Journal of Neuroscience JO - J. Neurosci. SP - 9508 LP - 9519 DO - 10.1523/JNEUROSCI.5689-12.2013 VL - 33 IS - 22 AU - Susanne V. Duncker AU - Christoph Franz AU - Stephanie Kuhn AU - Uwe Schulte AU - Dario Campanelli AU - Niels Brandt AU - Bernhard Hirt AU - Bernd Fakler AU - Nikolaus Blin AU - Peter Ruth AU - Jutta Engel AU - Walter Marcotti AU - Ulrike Zimmermann AU - Marlies Knipper Y1 - 2013/05/29 UR - http://www.jneurosci.org/content/33/22/9508.abstract N2 - The encoding of auditory information with indefatigable precision requires efficient resupply of vesicles at inner hair cell (IHC) ribbon synapses. Otoferlin, a transmembrane protein responsible for deafness in DFNB9 families, has been postulated to act as a calcium sensor for exocytosis as well as to be involved in rapid vesicle replenishment of IHCs. However, the molecular basis of vesicle recycling in IHCs is largely unknown. In the present study, we used high-resolution liquid chromatography coupled with mass spectrometry to copurify otoferlin interaction partners in the mammalian cochlea. We identified multiple subunits of the adaptor protein complex AP-2 (CLAP), an essential component of clathrin-mediated endocytosis, as binding partners of otoferlin in rats and mice. The interaction between otoferlin and AP-2 was confirmed by coimmunoprecipitation. We also found that AP-2 interacts with myosin VI, another otoferlin binding partner important for clathrin-mediated endocytosis (CME). The expression of AP-2 in IHCs was verified by reverse transcription PCR. Confocal microscopy experiments revealed that the expression of AP-2 and its colocalization with otoferlin is confined to mature IHCs. When CME was inhibited by blocking dynamin action, real-time changes in membrane capacitance showed impaired synaptic vesicle replenishment in mature but not immature IHCs. We suggest that an otoferlin-AP-2 interaction drives Ca2+- and stimulus-dependent compensating CME in mature IHCs. ER -