Developmental Cell
Volume 23, Issue 2, 14 August 2012, Pages 329-341
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Article
Kinocilia Mediate Mechanosensitivity in Developing Zebrafish Hair Cells

https://doi.org/10.1016/j.devcel.2012.05.022Get rights and content
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Summary

Mechanosensitive cilia are vital to signaling and development across many species. In sensory hair cells, sound and movement are transduced by apical hair bundles. Each bundle is comprised of a single primary cilium (kinocilium) flanked by multiple rows of actin-filled projections (stereocilia). Extracellular tip links that interconnect stereocilia are thought to gate mechanosensitive channels. In contrast to stereocilia, kinocilia are not critical for hair-cell mechanotransduction. However, by sequentially imaging the structure of hair bundles and mechanosensitivity of individual lateral-line hair cells in vivo, we uncovered a central role for kinocilia in mechanosensation during development. Our data demonstrate that nascent hair cells require kinocilia and kinocilial links for mechanosensitivity. Although nascent hair bundles have correct planar polarity, the polarity of their responses to mechanical stimuli is initially reversed. Later in development, a switch to correctly polarized mechanosensitivity coincides with the formation of tip links and the onset of tip-link-dependent mechanotransduction.

Highlights

► Kinocilia have a central role in mechanosensation in hair cell during development ► Functional polarity is reversed in developing, kinocilial-based mechanotransduction ► Functional polarity reverses during hair-cell development ► Reversal is coincident with a switch from kinocilial to stereocilial transduction

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