St. Jude Finds 'Dancing' Hair Cells Are Key to Humans' Acu...(und the cell body spontaneouslyelongates...),Health

Date:5/7/2008

und, the cell body spontaneously elongates and contracts along with the sound," said Jian Zuo, Ph.D., associate member of the St. Jude Department of Development Neurobiology. "It is very dramatic to see these hair cells 'dance' with the sound." Zuo is the senior author of a report on this work that appears in the May 8 issue of the journal "Neuron."

Since the prestin protein is the key component of somatic motility, in previous experiments Zuo and his colleagues genetically knocked out prestin in mice and tested the effects on hearing. Those mice showed a hearing defect that indicated a malfunction of somatic motility. While the knockout experiments were strong evidence for the role of somatic motility, the affected mice also showed structural abnormalities in their outer hair cells, Zuo said, thus complicating the interpretation.

In the new experiments to more unequivocally establish the role of somatic motility, the researchers genetically altered mice to have only subtle alterations in the prestin protein. These alterations only compromised prestin's function as an amplifier but did not otherwise affect the outer hair cell structure or function, the researchers' analysis showed.

"We found that these mice showed exactly the same kinds of hearing deficiency as the previous knockout mice," Zuo said. "Therefore, we believe that these experiments eliminate criticism of our earlier experiments with the knockout mice." The new experiments, Zuo said, thus firmly establish that the "dancing" somatic motility of the outer hair cells is critical to cochlear amplification.

However, he noted, "With this study we still cannot really exclude stereociliary motility from contributing to cochlear amplification, because eliminating somatic motility also reduces ciliary motility. So, it is not possible to totally isolate either form of motility. In fact, we hypothesize that the two mechanisms might work together in different aspects of amplificati
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SOURCE St. Jude Children's Research Hospital Copyright©2008 PR Newswire. All rights reserved

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