Optical Imaging of Intracellular Organelles for Understanding the Origin of the Circadian Calcium Rhythms

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19319
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 44:Biology at cellular to organismal levels, and related fields
• Research Institution: National Institutes of Natural Sciences
• Principal Investigator: Enoki Ryosuke 大学共同利用機関法人自然科学研究機構(機構直轄研究施設), 生命創成探究センター, 准教授 (00528341)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 概日リズム / 視交叉上核 / カルシウム / 光イメージング / オルガネラ

Outline of Final Research Achievements

The center of the mammalian circadian clock is located in the suprachiasmatic nucleus in the hypothalamus of the brain. I have previously identified spatiotemporally coordinated circadian Ca2+ rhythms in the neuronal circuits of the suprachiasmatic nucleus and investigated their underlying mechanisms. In this study, I performed organellar Ca2+ imaging using a high-resolution time-lapse imaging system and observed robust circadian Ca2+ rhythms in the nucleus that were in phase with cytosolic Ca2+ rhythms and had the identical spatial patterns in network. Drug application experiments revealed that the nuclear Ca2+ rhythm is mainly contributed by influx from outside the cell, probably through the nuclear membrane pore that allows Ca2+ entry into the nucleus.

Free Research Field

神経生理学

Academic Significance and Societal Importance of the Research Achievements

概日時計のリズム発振メカニズムを解明する上で、細胞内オルガネラレベルのリズム制御という新たな視点を与えるものであり、学術的に重要な結果である。また、高解像の超長期イメージング計測という、顕微鏡観察技術としても未開拓の領域を開くものであり、今後の更なる発展が期待できる。さらには、現代社会では概日リズムが乱れる事による心身の不調が問題になっており、概日時計のリズム発振の基本原理を解明することは、社会的にも意義があるものである。