Hormonal regulation of membrane transport proteins involved in acclimation of fishes to fresh water and seawater

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H03870
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Aquatic life science
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kato Akira 東京工業大学, 生命理工学院, 准教授 (40311336)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 魚類生理学 / イオントランスポーター / ホルモン受容体 / 輸送上皮細胞 / 淡水・海水適応

Outline of Final Research Achievements

The mechanism of water electrolyte metabolism of teleost fishes during acclimation to fresh water and seawater has become clearer at molecular level by the identification of membrane transport proteins in transport epithelia of the gill, intestine and kidney. The functions of the gill, intestine, and kidney are regulated by various hormones, however the mechanisms of hormonal regulations of these membrane transport proteins have not been clarified yet. We expressed various membrane transport proteins in Xenopus oocytes and analyzed the functions by electrophysiology. Expression analysis of a marine pufferfish Takifugu rubripes identified hormone receptors, aquaporins and a potassium channel expressed in the collecting duct cells, and proposed a novel model to explain the regulation of water reabsorption of the kidney of a marine teleost.

Free Research Field

魚類生理学

Academic Significance and Societal Importance of the Research Achievements

集合管は腎尿細管の最終部位として出口に位置し，膀胱へと流出する尿の組成を最終的に調節する重要な部位である。海水魚において集合管は活発に水とNaClを再吸収して尿量を減少させ，2価イオンを濃縮させた等張尿の産生と2価イオン排出に寄与する。一方，淡水魚集合管はNaClのみを活発に再吸収する一方で水は再吸収せず，その結果，多量の低張尿を産生し水排出に寄与する。すなわち，集合管を介した水再吸収制御は淡水・海水順応に極めて重要であるが，その分子機構は明らかでなかった。本研究により，海水魚の集合管に発現して尿量を制御する新たなメカニズムが明らかとなり，魚類生理学の発展に大きく寄与できるものと期待される。