Genetics

At the Tip of Hearing

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Science  19 Oct 2012:
Vol. 338, Issue 6105, pp. 305
DOI: 10.1126/science.338.6105.305-d
CREDIT: S. RIAZUDDIN ET AL., NAT. GENET. 44 10.1038/NG.2426 (2012)

Individuals with the hereditary disorder Usher syndrome suffer from hearing loss. Associated genetic mutations impair function of the inner ear, where sensory cells fail to convert sound waves into electrical signals. Riazuddin et al. have determined that mutations in the gene CIB2 contribute to Usher syndrome and nonsyndromic deafness. CIB2 encodes calcium and integrin binding protein 2, which is widely expressed in human and mouse tissue. In the mouse inner ear, the protein localizes to the tips of stereocilia of inner ear cells. When deflected by sound waves, ion channels in these hairlike projections open, triggering a mechanoelectrical signaling cascade. CIB2 interacts with whirlin, a protein that organizes molecular complexes that maintain stereocilia structure and growth. Suppression of CIB2 expression in zebrafish disrupted responses to acoustic stimuli and caused abnormal balance during movement. Overexpression of CIB2 in cultured cells decreased the release of calcium from intracellular stores. CIB2 may help to maintain intracellular calcium homeostasis in inner ear cells by sequestering calcium and influencing the release of stored calcium during mechanoelectrical signal transduction.

Nat. Genet. 44, 10.1038/ng.2426 (2012).

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