基于Parkin介导的线粒体自噬探讨七氟烷后处理对糖尿病心肌缺血再灌注损伤的作用机制

Mitophagy is one of the hallmarks of myocardial ischemia reperfusion injury (IRI). Understanding the regulatory mechanism controlling the degree of mitophagy would provide insights into the protection of myocardial IRI as well as leads for identifying new therapeutic targets. Recent findings demonstrated that sevoflurane postconditioning (SPC) protects against myocardial IRI. However, the protective effect of sevoflurane on diabetic myocardial IRI is minimal. The mechanism of sevoflurane lacks of protective effect on diabetic myocardial IRI remains largely unclear. .The stimulus to propose this grant application is our preliminary findings that Parkin, a mitochondrial housekeeper protein, is absent in diabetic myocardium, leading to mitophagy activation disorder and IRI aggravation. Myocardial IRI of diabetic rats with cardiac-specific overexpression of Parkin was effectively improved. More importantly, our previous results revealed that Parkin induced mitophagy is the important mechanism of SPC protection against myocardial IRI. .Thus, we hypothesize that the inhibited level of Parkin induced mitophagy lead to loss of SPC cardioprotective effect. As a corollary, activation of Parkin may possess a protective effect against IRI in diabetic rats and serves as a target for the protection against myocardial IRI. To address our hypothesis, we designed three specific aims: 1. We will research the effect of Parkin-induced mitophagy on diabetic myocardial IRI in molecular, cell, tissue and animal aspects; 2. To determine the protection of sevoflurane postconditioning against normal myocardial IRI by activating Parkin-induced mitophagy; 3. To probe the effect and molecular mechanism of SPC on diabetic myocardial IRI by restoring myocardial Parkin level..Successful accomplishment of the project will provide a novel mechanism for myocardial IRI and reveal the protective action of sevoflurane postconditioning on myocardial IRI by promoting Parkin-induced mitophagy. Results obtained from the project will also aid in the development of new preventive and therapeutic strategy for diabetic cardiomyopathy.

七氟烷后处理（SPC）对心肌缺血再灌注损伤（IRI）具有保护作用，但其在糖尿病心肌IRI中的保护作用并不明显，迄今该保护作用缺失的机制不明。预实验表明糖尿病心肌内Parkin减少，引起线粒体自噬激活障碍，易致IRI加重。心肌过表达Parkin的糖尿病大鼠IRI损伤有效改善。并且我们发现Parkin介导的线粒体自噬是SPC保护心肌IRI的重要机制。鉴此，我们提出假说：Parkin介导的线粒体自噬水平降低致SPC对糖尿病性心肌IRI失保护作用。我们将从分子、细胞、组织及动物水平等诸方面研究Parkin介导的线粒体自噬在糖尿病心肌中的作用；明确SPC通过促进Parkin介导的线粒体自噬保护正常心肌IRI；通过恢复糖尿病心肌内Parkin表达，探讨SPC对糖尿病心肌IRI的作用及分子机制。本研究以线粒体自噬为切入点研究SPC的心肌IRI保护机制，并为糖尿病心肌IRI的防治提供新思路。

Parkin介导的线粒体自噬水平被认为是七氟烷（SPC）对糖尿病心肌缺血再灌注损伤（IRI）起保护作用的重要机制。有研究表明Parkin介导的线粒体自噬可能在糖尿病心肌病变中发挥作用。但是Parkin介导的线粒体自噬在SPC对糖尿病心肌IRI发挥保护作用的机制还不明确。基于我们前期的研究成果，我们最初作出的假设是“Parkin介导的线粒体自噬水平降低导致SPC对糖尿病心肌IRI失去保护作用”。.为能够明确Parkin介导的线粒体自噬在SPC对糖尿病心肌IRI的保护中的作用机制。首先我们通过离体细胞（高糖处理大鼠心肌细胞模拟糖尿病心肌损伤）以及在体动物水平（SD大鼠构建糖尿病模型），通过改变Parkin蛋白表达水平从而调控线粒体自噬活性，研究Parkin介导的线粒体自噬缺乏在糖尿病心肌功能障碍及糖尿病心肌IRI中的作用。明确Parkin介导的线粒体自噬参与SPC对糖尿病心肌IRI保护的作用及分子调控机制。最终全面评估Parkin介导的线粒体自噬减轻导致SPC对糖尿病心肌IRI的失保护作用。.我们的研究成果进一步拓展Parkin的功能研究，率先阐明其介导的线粒体自噬在SPC对糖尿病心肌IRI保护中的作用，为治疗糖尿病心肌病提供潜在的干预靶点和思路，为心肌缺血再灌注损伤的保护机制增添新的实验支持和理论依据。最后Parkin过表达导致线粒体自噬水平明显升高从而改善糖尿病心肌的功能障碍并减轻糖尿病心肌IRI，研究证实Parkin介导的线粒体自噬减轻导致SPC对糖尿病心肌IRI的失保护作用，为将来临床应用Parkin调控线粒体自噬水平辅助SPC对糖尿病心肌IRI的保护等提供新思路，并且该研究对社会具有巨大的潜在社会效益。.综上所述，本项目证实Parkin介导线粒体自噬水平减轻导致SPC对糖尿病心肌IRI的失保护作用，项目发表了多篇相关论文，以达到预定目标。并且在本课题资助计划之外，本课题组联合院内兄弟学科以及省外优秀知名团队共同发表多篇论文，进一步探讨多种途径在心肌缺血性再灌注中的保护作用及其分子机制。