Abstract
Auditory hair cells form precise and sensitive staircase-like actin protrusions known as stereocilia. These specialized microvilli detect deflections induced by sound through the activation of mechano-electrical transduction (MET) channels located at their tips. At rest, a small MET channel current results in a constant calcium influx which regulates the morphology of the actin cytoskeleton in the shorter ‘transducing’ stereocilia. However, the molecular mechanisms involved in this novel type of activity-driven plasticity in the stereocilium cytoskeleton are currently unknown. Here, we tested the contribution of myosin XVA (MYO15A) isoforms, given their known roles in the regulation of stereocilia dimensions during hair bundle development and the maintenance of transducing stereocilia in mature hair cells. We used electron microscopy to evaluate morphological changes in the cytoskeleton of auditory hair cell stereocilia after the pharmacological blockage of resting MET currents in cochlear explants from mice that lacked one or all isoforms of MYO15A. Hair cells lacking functional MYO15A isoforms did not exhibit MET-dependent remodeling in their stereocilia cytoskeleton. In contrast, hair cells lacking only the long isoform of MYO15A exhibited increased MET-dependent stereocilia remodeling, including remodeling in stereocilia from the tallest ‘non-transducing’ row of the bundle. We conclude that MYO15A isoforms both enable and fine-tune the MET-dependent remodeling of the actin cytoskeleton in transducing stereocilia, while also contributing to the stability of the tallest row.
| Original language | English |
|---|---|
| Article number | 1482892 |
| Journal | Frontiers in Neurology |
| Volume | 15 |
| DOIs | |
| State | Published - 2024 |
Bibliographical note
Publisher Copyright:Copyright © 2024 López-Porras, Kruse, McClendon and Vélez-Ortega.
Funding
The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by the NIH/NIDCD R01DC021325 and R21DC017247 to A.C.V. Organ of Corti explants were fixed in cold formaldehyde/glutaraldehyde (3% each) in 0.1\u202FM sodium cacodylate buffer supplemented with 2\u202FmM of CaCl as described above. Samples were kept in fixative at 4\u00B0C for at least 24\u202Fh until further processing. Distilled water was used to rinse the samples, followed by dehydration through a graded series of ethanol (VWR, 89125-170). Subsequently, samples were subjected to critical point drying from liquid CO (Leica, CPD300) and coated with 5\u202Fnm platinum through sputter coating (Quorum Technologies, Q150T). Hair cells from the middle cochlear region (near the 50% point in cochlear length) were imaged with a field-emission scanning electron microscope (FEI, Helios Nanolab 660). This work was performed in part at the U.K. Electron Microscopy Center, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the National Science Foundation (NNCI-2025075). 2 2
| Funders | Funder number |
|---|---|
| National Institutes of Health (NIH) | |
| National Institute on Deafness and Other Communication Disorders | R21DC017247, R01DC021325 |
| U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China | NNCI-2025075 |
Keywords
- actin cytoskeleton
- hair cells
- mechanotransduction
- myosin XVA
- remodeling
- stereocilia
ASJC Scopus subject areas
- Neurology
- Clinical Neurology