Verification of Joule heat hypothesis in cell heat production

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H03987
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 43:Biology at molecular to cellular levels, and related fields
• Research Institution: Osaka University
• Principal Investigator: Nagai Takeharu 大阪大学, 産業科学研究所, 教授 (20311350)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 細胞熱化学 ジュール熱 / 温度プローブ / 熱消光 / 熱感受性弾性ポリペプチド

Outline of Final Research Achievements

Homeothermic animals maintain their body temperatures by the balance of the production and release of heat. Heat production in the animals is thought to involve shivering heat production in skeletal muscle and non-shivering heat production including heat production in brown adipose and beige adipose tissues and metabolic heat. Whereas the shivering heat production and metabolic heat are well understood, the detail of the non-metabolic non-shivering heat production remains still elusive. The present study has explored a previously-overlooked mechanism of the non-shivering heat production in which membrane potential drives ion flow through ion transporters such as ion channels and uncoupling protein 1, and the ion flow, one type of electric current, leads to Joule heat production, denoted as the Joule heat theory. This study conducted temperature imaging in cells and simulation of temperature distribution around channels to reveal the biological significance of this theory.

Free Research Field

生物物理学

Academic Significance and Societal Importance of the Research Achievements

恒温動物である哺乳類では、体内における熱産生によって体温の恒常性が維持されており、脳や内臓、褐色脂肪組織、そして筋肉が主な熱源と考えられる。体内における熱産生のうち、筋肉で起こる「ふるえ熱産生」のメカニズムについては研究が比較的進んでいるが、筋肉以外で起こる「非ふるえ熱産生」は解明があまり進んでいない。本研究は、「非ふるえ熱産生」に、従来見過ごされてきた熱産生メカニズムが存在する可能性を指摘したものである。今後、本成果を発展させることで、細胞内で起こる未知の熱産生プロセスの解明や、細胞内熱産生が関わる疾病メカニズムの詳細解明に資することが期待される。