title: Regulation of stereocilia length by myosin XVa and whirlin depends on the actin-regulatory protein Eps8.
abstract: Myosin XVa (MyoXVa) and its cargo whirlin are implicated in deafness and vestibular dysfunction and have been shown to localize at stereocilia tips and to be essential for the elongation of these actin protrusions [1-4]. Given that whirlin has no known actin-regulatory activity, it remains unclear how these proteins work together to influence stereocilia length. Here we show that the actin-regulatory protein Eps8 [5] interacts with MyoXVa and that mice lacking Eps8 show short stereocilia compared to MyoXVa- and whirlin-deficient mice. We show that Eps8 fails to accumulate at the tips of stereocilia in the absence of MyoXVa, that overexpression of MyoXVa results in both elongation of stereocilia and increased accumulation of Eps8 at stereocilia tips, and that the exogenous expression of MyoXVa in MyoXVa-deficient hair cells rescues Eps8 tip localization. We find that Eps8 also interacts with whirlin and that the expression of both Eps8 and MyoXVa at stereocilia tips is reduced in whirlin-deficient mice. We conclude that MyoXVa, whirlin, and Eps8 are integral components of the stereocilia tip complex, where Eps8 is a central actin-regulatory element for elongation of the stereocilia actin core.
authors.affiliation: Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Uri
authors.initials: U
authors.lastname: Manor
authors.forename: Andrea
authors.initials: A
authors.lastname: Disanza
authors.forename: M'Hamed
authors.initials: M
authors.lastname: Grati
authors.forename: Leonardo
authors.initials: L
authors.lastname: Andrade
authors.forename: Harrison
authors.initials: H
authors.lastname: Lin
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Di Fiore
authors.forename: Giorgio
authors.initials: G
authors.lastname: Scita
authors.forename: Bechara
authors.initials: B
authors.lastname: Kachar
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006198:Hair Cells, Auditory / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009218:Myosins / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; C083430:Eps8 protein, mouse; D008565:Membrane Proteins; C114013:Myo15 protein, mouse; C477218:Whrn protein, mouse; D009218:Myosins