TRIOBP: a novel actin bundler that generates resilient rootlets of inner ear hair cell stereocilia Center for Developmental Biology

Home > Seminars and Events > TRIOBP: a novel actin bundler that generates resilient rootlets of inner ear hair cell stereocilia

Category	Seminar
Date and Time	2010-04-02 16:00 - 17:00
Venue	Seminar Room A7F
Speaker	Shin-ichiro Kitajiri
Affiliation	Kyoto University School of Medicine
Title	TRIOBP: a novel actin bundler that generates resilient rootlets of inner ear hair cell stereocilia
Poster	click here to download(PDF)
Host	Raj Ladher
Summary	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 cross-linker in stereocilia. We generated Triobp-4/5 knockout mice that are profoundly deaf. Stereocilia of Triobp-4/5 knockout 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.