Macromolecular and electrical coupling between inner hair cells in the rodent cochlea

Philippe Jean, Tommi Anttonen, Susann Michanski, Antonio MG de Diego, Anna M. Steyer, Andreas Neef, David Oestreicher, Jana Kroll, Christos Nardis, Tina Pangršič, Wiebke Möbius, Jonathan Ashmore, Carolin Wichmann, Tobias Moser

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Jan 06, 2020
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Received Date: 17th December 19

Inner hair cells (IHCs) are the primary receptors for hearing. They are housed in the cochlea andconvey sound information to the brain via synapses with the auditory nerve. IHCs have beenthought to be electrically and metabolically independent from each other. We report that, upondevelopmental maturation, 30% of the IHCs are electrochemically coupled in ‘mini-syncytia’.This coupling permits transfer of fluorescently-labeled metabolites and macromolecular tracers.The membrane capacitance, Ca2+-current, and resting current increase with the number of dyecoupled IHCs. Dual voltage clamp experiments substantiate low resistance electrical coupling.Pharmacology and tracer permeability rule out coupling by gap junctions and purinoceptors. 3Delectron-microscopy indicates instead that IHCs are coupled by membrane fusion sites.Consequently, depolarization of one IHC triggers presynaptic Ca2+-influx at active zones in theentire mini-syncytium. Based on our findings and modeling, we propose that IHC-mini-syncytiaenhance sensitivity and reliability of cochlear sound encoding.

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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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