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Elife. 2015 Aug 24;4. doi: 10.7554/eLife.07830.

Neuropilin-2/Semaphorin-3F-mediated repulsion promotes inner hair cell innervation by spiral ganglion neurons.

Author information

1
Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, Bethesda, United States.
2
Department of Biology, Georgetown University, Washington, United States.

Abstract

Auditory function is dependent on the formation of specific innervation patterns between mechanosensory hair cells (HCs) and afferent spiral ganglion neurons (SGNs). In particular, type I SGNs must precisely connect with inner HCs (IHCs) while avoiding connections with nearby outer HCs (OHCs). The factors that mediate these patterning events are largely unknown. Using sparse-labeling and time-lapse imaging, we visualized for the first time the behaviors of developing SGNs including active retraction of processes from OHCs, suggesting that some type I SGNs contact OHCs before forming synapses with IHCs. In addition, we demonstrate that expression of Semaphorin-3F in the OHC region inhibits type I SGN process extension by activating Neuropilin-2 receptors expressed on SGNs. These results suggest a model in which cochlear innervation patterns by type I SGNs are determined, at least in part, through a Semaphorin-3F-mediated inhibitory signal that impedes processes from extending beyond the IHC region.

KEYWORDS:

Neuropilin; Semaphorin; auditory; axon guidance; cochlea; developmental biology; mouse; neuroscience; spiral ganglion neurons; stem cells

PMID:
26302206
PMCID:
PMC4566076
DOI:
10.7554/eLife.07830
[Indexed for MEDLINE]
Free PMC Article

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