Actin-Bundling Protein TRIOBP Forms Resilient Rootlets of Hair Cell Stereocilia Essential for Hearing

Kitajiri, Shin-ichiro, Sakamoto, Takeshi, Belyantseva, Inna A, Goodyear, Richard J, Stepanyan, Ruben, Fujiwara, Ikuko, Bird, Jonathan E, Riazuddin, Saima, Riazuddin, Sheikh, Ahmed, Zubair M, Hinshaw, Jenny E, Sellers, James, Bartles, James R, Hammer III, John A, Richardson, Guy P, Griffith, Andrew J, Frolenkov, Gregory I and Friedman, Thomas B (2010) Actin-Bundling Protein TRIOBP Forms Resilient Rootlets of Hair Cell Stereocilia Essential for Hearing. Cell, 141 (5). pp. 786-798. ISSN 0092-8674

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Abstract

Inner ear hair cells detect sound through deflection of mechanosensory stereocilia. Each stereocilium is supported by a paracrystalline array of parallel actin filaments that are packed more densely at the base, forming a rootlet extending into the cell body. The function of rootlets and the molecules responsible for their formation are unknown. We found that TRIOBP, a cytoskeleton-associated protein mutated in human hereditary deafness DFNB28, is localized to rootlets. In vitro, purified TRIOBP isoform 4 protein organizes actin filaments into uniquely dense bundles reminiscent of rootlets but distinct from bundles formed by espin, an actin crosslinker in stereocilia. We generated mutant Triobp mice (Triobp(Delta ex8/Delta ex8)) that are profoundly deaf. Stereocilia of Triobp(Delta ex8/Delta ex8) mice develop normally but fail to form rootlets and are easier to deflect and damage. Thus, F-actin bundling by TRIOBP provides durability and rigidity for normal mechanosensitivity of stereocilia and may contribute to resilient cytoskeletal structures elsewhere.

Item Type: Article
Schools and Departments: School of Life Sciences > Neuroscience
Depositing User: Richard Goodyear
Date Deposited: 06 Feb 2012 18:29
Last Modified: 30 Nov 2012 17:00
URI: http://srodev.sussex.ac.uk/id/eprint/16736
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