2023 Fiscal Year Final Research Report

Research in molecular and epidemiological cohort study of hereditary cardiovascular diseases

Research Project

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Project/Area Number	20H03927
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 58020:Hygiene and public health-related: including laboratory approach
Research Institution	Kanazawa University
Principal Investigator	Fujino Noboru 金沢大学, 保健学系, 教授 (40361993)
Co-Investigator(Kenkyū-buntansha)	林研至金沢大学, 保健学系, 准教授 (00422642) 野村章洋金沢大学, 附属病院, 特任准教授 (30707542) 高村雅之金沢大学, 医学系, 教授 (60362000) 朝野仁裕大阪大学, 大学院医学系研究科, 特任准教授(常勤) (60527670) 塚本蔵大阪大学, 大学院生命機能研究科, 准教授 (80589151) 中西千明金沢大学, 医学系, 協力研究員 (80623660) 多田隼人金沢大学, 附属病院, 助教 (90623653)
Project Period (FY)	2020-04-01 – 2024-03-31
Keywords	拡張型心筋症 / 遺伝学的検査 / 次世代シークエンサー / 肥大型心筋症 / 心不全 / 不整脈
Outline of Final Research Achievements	Cardiac myosin light chain kinase (cMLCK) phosphorylates ventricular myosin regulatory light chain 2 (MLC2v) and regulates sarcomere and cardiomyocyte organization. However, few data exist regarding the relationship between cMLCK mutations and MLC2v phosphorylation, in terms of developing familial dilated cardiomyopathy (DCM) in whom cMLCK gene mutations were identified. The purpose of the present study was to investigate functional consequences of cMLCK mutations. By mutation screening of unrelated 149 DCM probands, a truncation variant of c1915-1 g>t (p.Pro639Valfs*15) was identified. We generated the knock-in mice with the familial DCM-associated MYLK3 frameshift mutation and the human induced pluripotent stem cell-derived cardiomyocytes from the carrier of the mutation. The knock-in mice showed reduced cMLCK expression due to nonsense-mediated messenger RNA decay, reduced MLC2v phosphorylation in the myocardium, and systolic dysfunction in a cMLCK dose-dependent manner.
Free Research Field	心筋症
Academic Significance and Societal Importance of the Research Achievements	拡張型心筋症の１家系に、心筋型ミオシン軽鎖キナーゼ（cMLCK）をコードするMYLK3遺伝子変異p.Pro639Valfs*15を検出した。本変異が拡張型心筋症を発症させる分子機構を解明するため、ノックインマウスとiPS由来心筋細胞を作製し、心不全病態発症の分子機構を解析した。結果、心筋においてcMLCK活性が低下すると心筋型ミオシン調節軽鎖のリン酸化が阻害され、super relax stateと呼ばれる心筋ミオシンII分子の割合が増加し、心筋収縮性が低下することが明らかになった。さらに、開発したcMLCK活性化剤は、安全に血行動態を改善できる新たな心不全治療薬となることが期待される。