PT  - JOURNAL ARTICLE
AU  - Philippe Jean
AU  - Tommi Anttonen
AU  - Susann Michanski
AU  - Antonio MG de Diego
AU  - Anna M. Steyer
AU  - Andreas Neef
AU  - David Oestreicher
AU  - Jana Kroll
AU  - Christos Nardis
AU  - Tina Pangršič
AU  - Wiebke Möbius
AU  - Jonathan Ashmore
AU  - Carolin Wichmann
AU  - Tobias Moser
TI  - Macromolecular and electrical coupling between inner hair cells in the rodent cochlea
AID  - 10.1101/2019.12.17.879767
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2019.12.17.879767
4099  - http://biorxiv.org/content/early/2020/05/28/2019.12.17.879767.short
4100  - http://biorxiv.org/content/early/2020/05/28/2019.12.17.879767.full
AB  - Inner hair cells (IHCs) are the primary receptors for hearing. They are housed in the cochlea and convey sound information to the brain via synapses with the auditory nerve. IHCs have been thought to be electrically and metabolically independent from each other. We report that, upon developmental 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 dye-coupled IHCs. Dual voltage-clamp experiments substantiate low resistance electrical coupling. Pharmacology and tracer permeability rule out coupling by gap junctions and purinoceptors. 3D-electron-microscopy indicates instead that IHCs are coupled by membrane fusion sites. Consequently, depolarization of one IHC triggers presynaptic Ca2+-influx at active zones in the entire mini-syncytium. Based on our findings and modeling, we propose that IHC-mini-syncytia enhance sensitivity and reliability of cochlear sound encoding.Competing Interest StatementThe authors have declared no competing interest.