Abstract
Sound detection happens in the inner ear via the mechanical deflection of the hair bundle of cochlear hair cells. The hair bundle is an apical specialization consisting of actin-filled membrane protrusions (called stereocilia) connected by tip links (TLs) that transfer the deflection force to gate the mechanotransduction channels. Here, we identified the hearing loss-associated Loxhd1/DFNB77 gene as being required for the mechanotransduction process. LOXHD1 consists of 15 polycystin lipoxygenase α-toxin (PLAT) repeats, which in other proteins can bind lipids and proteins. LOXHD1 was distributed along the length of the stereocilia. Two LOXHD1 mouse models with mutations in the 10th PLAT repeat exhibited mechanotransduction defects (in both sexes). While mechanotransduction currents in mutant inner hair cells (IHCs) were similar to wild-type levels in the first postnatal week, they were severely affected by postnatal day 11. The onset of the mechanotransduction phenotype was consistent with the temporal progression of postnatal LOXHD1 expression/localization in the hair bundle. The mechanotransduction defect observed in Loxhd1-mutant IHCs was not accompanied by a morphologic defect of the hair bundle or a reduction in TL number. Using immunolocalization, we found that two proteins of the upper and lower TL protein complexes (Harmonin and LHFPL5) were maintained in the mutants, suggesting that the mechanotransduction machinery was present but not activatable. This work identified a novel LOXHD1-dependent step in hair bundle development that is critical for mechanotransduction in mature hair cells as well as for normal hearing function in mice and humans.
| Original language | English |
|---|---|
| Pages (from-to) | 3331-3343 |
| Number of pages | 13 |
| Journal | Journal of Neuroscience |
| Volume | 41 |
| Issue number | 15 |
| DOIs | |
| State | Published - Apr 14 2021 |
Bibliographical note
Publisher Copyright:Copyright © 2021 the authors.
Funding
The work was funded by Department of Otolaryngology-Head and Neck Surgery startup funding and National Institute on Deafness and Other Communication Disorders (NIDCD) Grant RO1-DC-016409-01A1, and Stanford Nano Shared Facilities seed grant (scanning electron microscopy work) for N.G.; and NIDCD Grant RO1-0003896 for A.R. The Stanford Nano Shared Facilities Are supported by the National Science Foundation Award ECCS-2026822. We thank Shari and Kenneth Eberts, the Oberndorf family, and the SICHL contributors for their support. We also thank Dr. Dáibhid Ó Maoiléidigh and Dr. Bertrand Coste for critical reading of previous versions of the manuscript; Ellen Ouyang, Navid Zebarjadi, and Yvonne Zuber for animal care; Lars Becker, Kyssia Mendoza, and Patrick Atkinson for fluorescence imaging; James Dewey, Anping Xia, and John Oghalai (University of Southern California, Los Angeles, CA) for audiometry; Ulrich Müller (John Hopkins University School of Medicine, Baltimore, MD) for his support; David Furness (Keele University, Keele, UK) for sharing TMC1 antibody; and Christopher Cunningham for resources. In addition, we thank Enago (https://www.enago.com/) for the English language review, and SciStyle (https://www.scistyle.com/) for the graphical abstract. The work was funded by Department of Otolaryngology-Head and Neck Surgery startup funding and National Institute on Deafness and Other Communication Disorders (NIDCD) Grant RO1-DC-016409-01A1, and Stanford Nano Shared Facilities seed grant (scanning electron microscopy work) for N.G.; and NIDCD Grant RO1-0003896 for A.R. The Stanford Nano Shared Facilities Are supported by the National Science Foundation Award ECCS-2026822. We thank Shari and Kenneth Eberts, the Oberndorf family, and the SICHL contributors for their support. We also thank Dr. Dáibhid Ó Maoiléidigh and Dr. Bertrand Coste for critical reading of previous versions of the manuscript; Ellen Ouyang, Navid Zebarjadi, and Yvonne Zuber for animal care; Lars Becker, Kyssia Mendoza, and Patrick Atkinson for fluorescence imaging; James Dewey, Anping Xia, and John Oghalai (University of Southern California, Los Angeles, CA) for audiometry; Ulrich Müller (John Hopkins University School of Medicine, Baltimore, MD) for his support; David Furness (Keele University, Keele, UK) for sharing TMC1 antibody; and Christopher Cunningham for resources. In addition, we thank Enago (https://www.enago.com/) for the English language review, and SciStyle (https://www.scistyle.com/) for the graphical abstract. *A.T. and K.K.M. have contributed equally to this work. Correspondence should be addressed to Nicolas Grillet at [email protected]. https://doi.org/10.1523/JNEUROSCI.0975-20.2021 Copyright © 2021 Trouillet, Miller et al.
| Funders | Funder number |
|---|---|
| John Hopkins University School of Medicine, Baltimore, MD | |
| University of Southern California | |
| Department of Otolaryngology-Head and Neck Surgery | |
| Ulrich Müller | |
| National Science Foundation Arctic Social Science Program | 2026822 |
| National Institute on Deafness and Other Communication Disorders | RO1-0003896, R01DC016409 |
Keywords
- Hair cell
- LOXHD1
- Mechanotransduction
- Nonsense-associated altered splicing
- PLAT domain
- Stereocilia
ASJC Scopus subject areas
- General Neuroscience