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ORIGINAL RESEARCH article

Front. Audiol. Otol.

Sec. Auditory Science

Volume 3 - 2025 | doi: 10.3389/fauot.2025.1605980

Microtubule-associated protein 2 (MAP2) deficiency causes high-frequency hearing loss

Provisionally accepted
  • 1Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Japan
  • 2School of Pharmacy, Nihon University, Funabashi, Chiba, Japan
  • 3Graduate School of Medicine, Osaka University, Suita, Ōsaka, Japan

The final, formatted version of the article will be published soon.

The role of microtubule-associated proteins (MAPs) in neuronal morphogenesis is well-investigated; however, their specific contribution to the sensory nervous system remains largely unexplored. In this study, we examined the role of MAP2 in auditory sensing, which critically depends on the cytoskeletal structure. Four-week-old Map2 homozygous knockout (Map2−/−) mice exhibited auditory sensitivity equivalent to that of wild-type mice. However, auditory brainstem responses (ABRs) revealed that 16-week-old Map2−/− mice exhibited a 30-dB reduction in hearing sensitivity, with a more pronounced effect at higher frequencies. The ABR wave V peak latency pattern showed a loss of nonlinearity in 16-week-old Map2−/− mice. The latency of the ABR wave V further suggested that this reduction was not due to conductive hearing loss. Whole-mount cochlear immunostaining indicated that MAP2 was expressed in the cell bodies of cochlear inner hair cells (IHCs) and outer hair cells (OHCs) in wildtype mice. Notably, MAP2 expression in cochlear hair cells was higher in the basal region, Map2−/− mice had fewer OHCs in the base region, corresponding to high-frequency hearing aligned with ABR measurements. Furthermore, the density and morphology of spiral ganglion neurons were not affected by the loss of MAP2. These findings suggest that MAP2 contributes to the maintenance of hearing sensitivity and plays an important role in cochlear hair cells, particularly in the high-frequency range.

Keywords: MAP2, cochlea outer hair cell, Hearing Loss, Inner ear, Cytoskeleton, Stereocilia

Received: 04 Apr 2025; Accepted: 16 Sep 2025.

Copyright: © 2025 Shin’ya, Miyasaka, Harada and Kobayasi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Tomohiro Miyasaka, miyasaka.tomohiro@nihon-u.ac.jp
Kohta I Kobayasi, kkobayas@mail.doshisha.ac.jp

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