高表达肌浆网钙离子ATP酶在心力衰竭中保护机制的研究

In the mammalian myocardium, Ca2+ homeostasis plays a critical role in maintaining cardiac physiological function. Cardiac sarcoplasmic reticulum Ca2+-ATPase (SERCA2) is responsible for most of the Ca2+ removal during diastole and the largest Ca2+ handling energy consumer in excitation-contraction (E-C) coupling.Clinica studies have shown down-regulation of SERCA2a expression in heart faiure patients. Overexpression of SERCA2a has been suggested to be a strategic intervention for cardiac failure. To understand the cardiac performance under long-term SERCA2a overexpression conditions, we for the first time established SERCA2a transgenic (TG) Wistar rat to analyze cardiac mechanical works and energetics in excised blood-perfused hearts using cross-circulation system.SERCA2a protein expression was increased in TG rats, and phospholamban (PLB) was significantly decreased in TG and thus SERCA2a/PLB in TG was significantly larger than that in wild type (WT).Meanwhile, to clarify the protective effects of long-term SERCA2a overexpression in acute and chronic heart faiure models, we compare the heart function, mitochondaria function and cardiac apoptotic signal pathway after cardiac ischemia-reperfusion and cardiac infarction.Results will show that TG rats have no difference with WT rats in cardiac function under physiological conditions; in response acute and chronic heart failure, TG rats will show less cardiac dysfunction, mitochondrial dysfunction and cardiac tissue apoptosis.Our results will firstly provide the basic data of cardiac mechanical works and energetics for long-term overexpression of SERCA2a under physiological conditions,it also will ellucidate the protective effects for overexpression of SERCA2a in heart failure models.Our results will provide solid basic data for clinical treatment in heart faiure patients with long-term overexpression of SERCA2a.

心力衰竭严重威胁着人类健康,临床患者表现为心肌细胞内肌浆网钙离子ATP酶(sarcoplasmic reticulum Ca2+ ATPase, SERCA2a)蛋白质表达低下，通过提高SERCA2a功能以改善患者心功能的基础研究还十分匮乏。本课题通过转基因技术使大鼠长期高表达SERCA2a，研究在生理状态下高表达SERCA2a对心脏形态和功能的影响，特别是在能量利用和转换中的影响；同时，通过比较野生型和转基因型大鼠对心脏缺血-再灌流和心肌梗死两种模型中心功能的受损，明确转基因型长期提高心脏SERCA2a表达对心脏的保护作用，同时探讨可能的保护机制。本课题将提供高表达SERCA2a对生理和病理状态影响的基础数据，为定点靶基因疗法在临床心力衰竭患者病患者中的应用提供坚实的理论依据，为临床治疗心力衰竭患者提供新思路和新策略。

心力衰竭严重威胁着人类健康,临床患者表现为心肌细胞内肌浆网钙离子 ATP 酶(sarcoplasmic reticulum Ca2+ ATPase, SERCA2a)蛋白质表达低下，通过提高 SERCA2a 功能以改善患者心功能的基 础研究还十分匮乏。本课题通过转基因技术使大鼠长期高表达 SERCA2a，观察到生理状态下高表达 SERCA2a 对心脏形态和功能的均无显著影响，同时在能量利用和转换中也无显著影响；同时，通过比较野生型和转基因型大鼠对心脏缺血-再灌流心功能的受损，确定了转基因型长期提高心脏 SERCA2a 表达对心脏缺血-再灌流损伤具有保护作用，其作用机制可能是缺血再灌注之后转基因型大鼠心肌细胞线粒体对Ca2+超载有一定的抵抗性，同时心肌组织中促凋亡蛋白的下降和抗凋亡蛋白Bcl-2与促凋亡蛋白Bax比值的升高以及转基因型大鼠高表达的自噬相关蛋白引起的。另外，在慢性心功能下降（异丙肾上腺素诱导-4周）模型中，遗传性高表达SERCA2a保护心脏的作用机制可能是通过长期上调线粒体ATP合成酶的控制基因线粒体转录因子A的转录使转基因型大鼠表达更高的TFAM蛋白，同时转基因大鼠心脏在收缩过程中耗氧更少，从而改善了慢性心力衰竭进程中心脏收缩和舒张功能的下降。本课题提供了高表达 SERCA2a 对生理和病理状态影响的基础数据，为定点靶基因疗法在临床心力衰竭患者病患者中的应用提供坚实的理论依 据，为临床治疗心力衰竭患者提供新思路和新策略。