Elucidation of molecular entities responsible for unique electrochemical property of the cochlear lateral wall

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K17736
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: General physiology; General pharmacology
• Research Institution: Niigata University
• Principal Investigator: Sawamura Seishiro 新潟大学, 医歯学系, 助教 (10781974)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 内耳蝸牛 / イオン輸送 / トランスポーター

Outline of Final Research Achievements

The cochlea in the inner ear is filled with a unique extracellular solution that exhibits a highly positive potential of +80 mV. This property is essential for hearing and likely to be maintained by ion transport across cochlear lateral wall made up of two epithelial layers. In our earlier work, we found that the outer layer of the lateral wall has Na+ permeability which contributes to highly positive endocochlear potential. Nevertheless, its molecular entity remained elusive. In this study, we identified 5 channels and 19 transporters expressed in the outer layer by proteomic analysis. In addition, by in vitro and in vivo electrophysiological experiments, we found that one of the transporters showed Na+ permeability and perfusion of its inhibitor to the cochlea decreased endocochlear potential. These results suggest that the identified transporter has essential role in the Na+ permeability of the lateral wall and maintenance of electrochemical property of the cochlea.

Free Research Field

分子生理学

Academic Significance and Societal Importance of the Research Achievements

内耳性障害性難聴に対する効果的な治療法は未だほとんどない。この課題を解決するためには、内耳蝸牛の聴覚機能に関する理解を深めることが重要である。本研究では、これまであまり調べられてこなかった蝸牛側壁外層に発現するタンパク質を網羅的に解析し、聴覚に必須な内耳電位の維持に関わる新たなイオン輸送体を同定した。この成果は、聴覚生理の基礎的知見を広げるだけでなく、難聴の病因解明や治療法の開発に役立つことが期待される。