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Actin-Bundling Protein TRIOBP Forms Resilient Rootlets of Hair Cell Stereocilia Essential for Hearing
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posted on 2023-06-07, 20:15 authored by Shin-ichiro Kitajiri, Takeshi Sakamoto, Inna A Belyantseva, Richard GoodyearRichard Goodyear, Ruben Stepanyan, Ikuko Fujiwara, Jonathan E Bird, Saima Riazuddin, Sheikh Riazuddin, Zubair M Ahmed, Jenny E Hinshaw, James Sellers, James R Bartles, John A Hammer III, Guy Richardson, Andrew J Griffith, Gregory I Frolenkov, Thomas B FriedmanInner 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.
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Publication status
- Published
Journal
CellISSN
0092-8674External DOI
Issue
5Volume
141Page range
786-798Pages
13.0Department affiliated with
- Neuroscience Publications
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- No
Peer reviewed?
- Yes
Legacy Posted Date
2012-02-06Usage metrics
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