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bioRxiv · 10.1101/317172

Spontaneous and coordinated Ca2+ activity of cochlear sensory and non-sensory cells drives the maturation of OHC afferent innervation

Ceriani, F.·Hendry, A.·Jeng, J.-Y.·Johnson, S.·Olt, J.·Holley, M. C.·Mammano, F.·Kros, C. J.·Simmons, D. D.·Marcotti, W.
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Abstract

Outer hair cells (OHCs) are highly specialized sensory cells conferring the fine tuning and high sensitivity of the mammalian cochlea to acoustic stimuli. Here, by genetically manipulating spontaneous Ca2+ signalling in vivo, through a period of early postnatal development, we find that the refinement of OHC afferent innervation is regulated by complementary spontaneous Ca2+ signals originating in OHCs and non-sensory cells. OHCs fire spontaneous Ca2+ spikes during a narrow period of immature development. Simultaneously, waves of Ca2+ activity in the non-sensory greater epithelial ridge act, via ATP-induced activation of P2X receptors, to synchronize OHC firing, resulting in the refinement of their afferent innervation. In the absence of connexin channels Ca2+ waves are impaired, leading to a reduction in the number of ribbon synapses and afferent fibres on OHCs. We propose that the correct maturation of the afferent connectivity in OHCs requires experience-independent Ca2+ signals from sensory and non-sensory cells.

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Ceriani, F., Hendry, A., Jeng, J.-Y., Johnson, S., Olt, J., Holley, M. C., Mammano, F., Kros, C. J., Simmons, D. D., Marcotti, W.. 2018-05-08. Spontaneous and coordinated Ca2+ activity of cochlear sensory and non-sensory cells drives the maturation of OHC afferent innervation. https://doi.org/10.1101/317172

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