Molecular mechanism of self-regulation of Cav1.2 channel by channel cytoplasmic fragments

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K07285
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 48020:Physiology-related
• Research Institution: Kagoshima University
• Principal Investigator: Xu Jianjun 鹿児島大学, 医歯学域医学系, 講師 (10581689)
• Co-Investigator(Kenkyū-buntansha): 亀山 正樹 鹿児島大学, 医歯学総合研究科, 客員研究員 (60150059)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: カルシムチャネル / 心筋細胞 / カルモジュリン / pull-down assay / パッチクランプ法 / 自己調節 / イオンチャネル

Outline of Final Research Achievements

In this study, we examined the interaction between cytoplasmic fragments of Cav1.2 channel, and elucidated the role of fragments in the regulation of the channel. Using pulldown assay, we examined CaM binding to N terminus (NT), proximal C terminus (CT1), the loop between repeat I-II, II-III and III-IV (LI-II, LII-III and LIII-IV). We found that at high Ca2+, CaM bound to CT1, NT and LI-II. C lobe of CaM had highest binding affinity for CT1 while N lobe for NT. There was no direct interaction between NT and CT1, however, N and C terminus were bridged by Ca2+/CaM with N lobe/N terminus and C lobe/C terminus interactions. In addition, there was a direct interaction between NT and LI-II, independent of Ca2+/CaM. The electrophysiological experiments with WT CaM (N lobe-C lobe) and its mutants N-N CaM (N lobe-N lobe), C-C CaM (C lobe-C lobe) indicates that C lobe CDI contributes to major CDI, while N lobe CDI is responsible for minor CDI. Both N and C lobe are required for complete CDI.

Free Research Field

神経筋生理学

Academic Significance and Societal Importance of the Research Achievements

Cav1.2カルシウムチャネル(Cav1.2チャネル)は、心臓、脳、内分泌細胞、平滑筋で広く発現しており、その機能不全が心不全、不整脈、神経精神障害などの多系統障害を引き起こす可能性がある。 従って、Cav1.2チャネルの調節機構を解明することは、これらの疾患の新しい治療戦略を開発するために重要である。