缓慢心律失常新机制---circRNA4.41通过miR-30d/TRPM7通路调节窦房结区电重构

The undefined electrophysiological mechanism is the reason for low effective clinical medicine treatment for bradycardiac arrhythmia. The electrical remodeling caused by the imbalance of ion channels in the sinus node is an important cause of arrhythmia and sudden cardiac death. TRPM7 is a bifunctional ion channel protein which contains both ion channel domain and protein kinase domain.Premenstrual study found that TRPM7 expression in sinoatrial node of the model of bradyarrhythmia decreased, while HCN4, Cav1.2, Cav3.1 expression decreased. Noncoding RNA participates in diverse processes of many cells. However, its function in bradycardiac arrhythmia is unclear. We suppose that the expression of circ-ZMYM4.41 is abnormal, and its adsorption to miR-30d is weakened, thus enhancing the function of miR-30d and inhibiting its protein expression by binding to TRPM73'UTR. TRPM7 affects the pacemaker current through the channel structure， and affects the ion channel expression in the sinoatrial node cells through the kinase structure . The project for the first time proposed to non-coding RNA as the target regulation of sinoatrial electrical remodeling, prevention and treatment of bradyarrhythmias. This study will provide theoretical basis and therapeutic targets for the prevention and treatment of bradyarrhythmia and sudden cardiac death.

缓慢心律失常临床药物治疗效果差，主要原因是其电生理机制尚不明确。由窦房结离子通道失衡引起的电重构是导致心律失常和心源性猝死的重要原因。TRPM7是具有离子通道和蛋白激酶双重结构域的双功能通道蛋白。前期研究发现TRPM7在缓慢心律失常动物模型窦房结的表达下降，同时HCN4、Cav1.2、Cav3.1表达下降。非编码RNA参与细胞多种生命进程调控，但其对缓慢心律失常的影响及机制尚不清楚。本研究提出：circ-ZMYM4.41表达异常，对miR-30d的吸附作用减弱，从而使miR-30d功能增强，通过与通道酶TRPM7 3’UTR区结合抑制其蛋白表达。TRPM7通过通道结构影响起搏电流，通过激酶结构影响窦房结细胞离子通道表达。本项目首次提出以非编码RNA为靶点调控窦房结电重构，防治缓慢心律失常。本研究将为防治缓慢心律失常及心源性猝死提供理论依据和治疗靶点。

在本课题的资助下共发表SCI文章4篇，另有部分数据正在整理，准备投稿。本项目通过非选择性β受体阻断药普萘洛尔及幼年大鼠甲状腺切除成功构建缓慢心率失常动物模型，并发现普萘洛尔可以不依赖β受体途径影响心脏起搏相关离子通道HCN4、 Cav3.1、TRPM7、NCX1mRNA及蛋白表达。证明复方中药制剂参仙升脉口服液通过上调起搏相关离子通道HCN4、Cav3.1、NCX1、TRMP7 mRNA及蛋白表达缓解普萘洛尔所致大鼠缓慢性心律失常。开展非编码circRNA在动脉硬化动物模型主动脉表达差异研究，进而开展内源性活性物质对VSMCs表型转化及血管新生内膜增生性疾病的影响及机制研究。发现在动脉硬化动物模型中表达升高的mmu_CircRNA_36781、mmu_CircRNA_37699 通过下调miR-30d-3p和miR-140-3p，上调其靶蛋白MAP2K6、TP53RK调控内皮损伤和动脉粥样硬化病理进程。发现血管内膜增生过程中髓源性生长因子（MYDGF）的含量下降，证明MYDGF通过与S1PR2结合激活RHOA/ROCK通路促进G-Actin装配成F-Actin，抑制G-Actin与MRTFs结合，促进MRTFs的核移位，从而维持分化相关基因的表达。开展新型蒽醌化合物KLX在心血管方面药理作用及作用机制研究。证明KLX 激活内皮细胞 AMPK、AKT 及其下游 eNOS 磷酸化，促进NO 的合成和释放，降低动脉血管张力；通过激活FGFR/ERK通路促进血管新生，加速糖尿病伤口愈合；通过抑制TGF-β1/ERK1/2非经典信号通路，改善心肌间质纤维化，保护心脏功能。本项目在基础理论研究及应用方面均有较大突破。