title: Progressive hearing loss and gradual deterioration of sensory hair bundles in the ears of mice lacking the actin-binding protein Eps8L2.
abstract: Mechanotransduction in the mammalian auditory system depends on mechanosensitive channels in the hair bundles that project from the apical surface of the sensory hair cells. Individual stereocilia within each bundle contain a core of tightly packed actin filaments, whose length is dynamically regulated during development and in the adult. We show that the actin-binding protein epidermal growth factor receptor pathway substrate 8 (Eps8)L2, a member of the Eps8-like protein family, is a newly identified hair bundle protein that is localized at the tips of stereocilia of both cochlear and vestibular hair cells. It has a spatiotemporal expression pattern that complements that of Eps8. In the cochlea, whereas Eps8 is essential for the initial elongation of stereocilia, Eps8L2 is required for their maintenance in adult hair cells. In the absence of both proteins, the ordered staircase structure of the hair bundle in the cochlea decays. In contrast to the early profound hearing loss associated with an absence of Eps8, Eps8L2 null-mutant mice exhibit a late-onset, progressive hearing loss that is directly linked to a gradual deterioration in hair bundle morphology. We conclude that Eps8L2 is required for the long-term maintenance of the staircase structure and mechanosensory function of auditory hair bundles. It complements the developmental role of Eps8 and is a candidate gene for progressive age-related hearing loss.
authors.affiliation: Institute for Science and Technology in Medicine, Keele University, Keele ST5 5BG, United Kingdom.
authors.forename: David N
authors.initials: DN
authors.lastname: Furness
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Johnson
authors.forename: Uri
authors.initials: U
authors.lastname: Manor
authors.forename: Lukas
authors.initials: L
authors.lastname: Rüttiger
authors.forename: Arianna
authors.initials: A
authors.lastname: Tocchetti
authors.forename: Nina
authors.initials: N
authors.lastname: Offenhauser
authors.forename: Jennifer
authors.initials: J
authors.lastname: Olt
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Goodyear
authors.forename: Sarath
authors.initials: S
authors.lastname: Vijayakumar
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Dai
authors.forename: Carole M
authors.initials: CM
authors.lastname: Hackney
authors.forename: Christoph
authors.initials: C
authors.lastname: Franz
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Di Fiore
authors.forename: Sergio
authors.initials: S
authors.lastname: Masetto
authors.forename: Sherri M
authors.initials: SM
authors.lastname: Jones
authors.forename: Marlies
authors.initials: M
authors.lastname: Knipper
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Holley
authors.forename: Guy P
authors.initials: GP
authors.lastname: Richardson
authors.forename: Bechara
authors.initials: B
authors.lastname: Kachar
authors.forename: Walter
authors.initials: W
authors.lastname: Marcotti
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001300:Audiometry, Evoked Response; D006198:Hair Cells, Auditory / Q000473:pathology* / Q000502:physiology / Q000648:ultrastructure; D034381:Hearing Loss / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000172:deficiency* / Q000235:genetics; D008854:Microscopy, Electron; D018408:Patch-Clamp Techniques
chemical_list: C584432:Eps8L2 protein, mouse; D008840:Microfilament Proteins
keywords: deafness; ion channel; sensory system
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