L型钙离子通道Cav1.2的O-GlcNAc修饰在糖尿病心肌病致室性心律失常中的作用及机制研究

Ventricular arrhythmia is one of the main causes of sudden cardiac death in the patients with diabetic cardiomyopathy (DCM). Studies demonstrate that O-GlcNAc modification of cardiac ion channel related proteins play an important role in the ventricular arrhythmia. L-type calcium channel Cav1.2 is a key component of formation of action potential, and the dysfunction of Cav1.2 leads to various malignant arrhythmia. However, the role and molecular mechanisms of Cav1.2 in DCM based arrhythmia remains unknown. Our preliminary experiments showed that Cav1.2 channel could be modified by O-GlcNAc in the rat DCM model. Hence, we speculate that the dysfunction of Cav1.2 is caused by O-GlcNAc modification, which lead to the arrhythmia in DCM. To confirm this hypothesis, the high level of glucose induced cardiomyocyte model and the rat DCM model will be used. In addition, the role and mechanism of O-GlcNAc modification of Cav1.2 in the DCM-derived ventricular arrhythmia will be studied with electrocardiogram telemetry records, mass spectrum, co-immunoprecipitation, laser scanning confocal microscopy and patch clamp approaches. The results will provide a theoretical and experimental basis for clinical prevention and treatment of ventricular arrhythmia in DCM.

室性心律失常是导致糖尿病性心肌病（DCM）患者猝死的主要原因。有研究证实离子通道相关作用蛋白的O-糖基化（O-GlcNAc）修饰在心律失常发生中扮演重要角色。L型钙离子通道Cav1.2参与心肌动作电位的产生，其功能异常可引发室性心律失常，但Cav1.2在DCM致室性心律失常的发生作用与机制尚不明确。我们预实验发现大鼠DCM模型中Cav1.2存在O-GlcNAc修饰。故提出科学假说：Cav1.2能够通过O-GlcNAc 修饰引起钙通道功能异常，进而参与DCM致室性心律失常的发生。我们拟在细胞水平（高糖刺激原代心肌细胞）和动物水平（大鼠DCM模型），采用心电遥测记录、质谱分析、免疫共沉淀、激光共聚焦、细胞膜片钳等技术和方法，探讨 Cav1.2 的O-GlcNAc 修饰在 DCM 致室性心律失常中的作用及其机制，为临床预防和治疗DCM室性心律失常提供理论基础和实验依据。

室性心律失常是导致糖尿病性心肌病（DCM）患者猝死的主要原因。有研究证实离子通道相关作用蛋白的O-糖基化（O-GlcNAc）修饰在心律失常发生中扮演重要角色。L型钙离子通道Cav1.2参与心肌动作电位的产生，其功能异常可引发室性心律失常，但Cav1.2在DCM致室性心律失常的发生作用与机制尚不明确。本团队首次发现大鼠DCM模型中Cav1.2存在O-GlcNAc修饰。推测Cav1.2能够通过O-GlcNAc 修饰引起钙通道功能异常，进而参与DCM致室性心律失常的发生。课题组成员在本国家自然科学基金的指导和资助下，按照国家基金委管理条例和项目计划，严格实施并顺利完成课题研究内容。先后通过心电图记录与分析、质谱分析、免疫共沉淀、蛋白免疫印迹等技术，发现Cav1.2可被O-GlcNAc修饰，且与野生型相比，糖尿病大鼠心脏组织蛋白O-GlcNAc 修饰水平和Cav1.2蛋白表达水平均显著升高，此外，与野生型相比，糖尿病大鼠QT间期延长。