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This Article Full Text Full Text (PDF) All Versions of this Article: 576/3/801    most recent jphysiol.2006.118547v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stepanyan, R. Articles by Frolenkov, G. I. Search for Related Content PubMed PubMed Citation Articles by Stepanyan, R. Articles by Frolenkov, G. I. Related Collections Neuroscience

¹ Department of Physiology, University of Kentucky, Lexington, KY, USA
² Laboratory of Molecular Genetics
³ Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD, USA

In hair cells of all vertebrates, a mechanosensory bundle is formed by stereocilia with precisely graded heights. Unconventional myosin-XVa is critical for formation of this bundle because it transports whirlin and perhaps other molecular components responsible for programmed elongation of stereocilia to the stereocilia tips. A tip of a stereocilium is the site of stereocilia growth and one of the proposed sites of mechano-electrical transduction. In adult shaker 2 mice, a mutation that disables the motor function of myosin-XVa results in profound deafness and abnormally short stereocilia that lack stereocilia links, an indispensable component of mechanotransduction machinery. Therefore, it was assumed that myosin-XVa is required for proper formation of the mechanotransduction apparatus. Here we show that in young postnatal shaker 2 mice, abnormally short stereocilia bundles of auditory hair cells have numerous stereocilia links and ‘wild type’ mechano-electrical transduction. We compared the mechanotransduction current in auditory hair cells of young normal-hearing littermates, myosin-XVa-deficient shaker 2 mice, and whirler mice that have similarly short stereocilia but intact myosin-XVa at the stereocilia tips. This comparison revealed that the absence of functional myosin-XVa does not disrupt adaptation of the mechanotransduction current during sustained bundle deflection. Thus, the hair cell mechanotransduction complex forms and functions independently from myosin-XVa-based hair bundle morphogenesis.

(Received 2 August 2006; accepted after revision 11 September 2006; first published online 14 September 2006)
Corresponding author G. Frolenkov: Department of Physiology, University of Kentucky, MS508, Chandler Medical Center, 800 Rose Street, Lexington, KY 40536, USA. Email: gregory.frolenkov{at}uky.edu

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