Mechanisms of glucose mediated cardiac mitochondrial dysfunction

描述(申请人提供)：心力衰竭是糖尿病患者死亡的主要原因。心力衰竭的部分特征是线粒体功能障碍，其定义是氧化能力和ATP合成减少。糖尿病伴随一系列全身性变化，包括高脂血症和高血糖。在确定导致糖尿病相关并发症发展的分子机制方面，一个关键障碍是是否有合适的体内模型来单独测试每种模型。为了确定葡萄糖输送到心脏在线粒体功能调节中的作用，我们建立了一个小鼠模型，用于诱导心肌细胞特异性表达葡萄糖转运蛋白GLUT4。从而使我们能够直接测试心肌细胞葡萄糖输送在健康和患病心脏中所起的作用。我们的初步数据定义了一个模型，即在基础状态下增加葡萄糖的输送可以提高葡萄糖的利用率。与之形成鲜明对比的是，在高血糖的情况下，葡萄糖供应增加会加速线粒体功能障碍的发展。我研究的长期目标是确定控制心脏线粒体代谢功能的机制。在这项提案中，我们将从调查 通过检测葡萄糖递送调节线粒体蛋白的翻译后修饰(AIM 1)和表观遗传控制氧化磷酸化(OXPHOS)基因表达(AIM 2)，研究葡萄糖介导的线粒体调节的作用。后一种过程最近因其对“血糖记忆”的贡献而受到极大关注，“血糖记忆”被定义为先前的血糖浓度对持续增加糖尿病并发症风险的影响，与当前的血糖控制水平无关。针对具体目标1，我们将确定翻译后修饰的线粒体蛋白的O-连接GlcNacyl化，这种修饰随着糖尿病的增加而增加，并开始探索葡萄糖输送对线粒体氧化能力和酶功能的功能后果。目标2中概述的研究将确定表观遗传修饰的作用，这些修饰与OXPHOS基因表达的变化有关，而OXPHOS基因表达是由葡萄糖唯一调节的。该提案的初始K99阶段将促进蛋白质组学(2D-PAGE和质谱学)和表观遗传学(组蛋白修饰和DNA甲基化)方面的培训。这一额外的培训将为我提供知识和技能，使我能够独立实现我的短期目标，即找到一个终身教职跟踪职位(R00阶段)，这是完成提案目标并追求我在确定心脏功能障碍分子机制方面的兴趣所必需的。总而言之，这些研究的完成将为血糖在糖尿病心肌病和线粒体功能障碍发展中的机制基础提供基本的见解。

DESCRIPTION (provided by applicant): Heart failure is a major cause of death in individuals with diabetes. Heart failure is characterized in part by mitochondrial dysfunction defined by decreased oxidative capacity and ATP synthesis. Diabetes is accompanied by a number of systemic changes including hyperlipidemia and hyperglycemia. A critical barrier in determining the molecular mechanisms that lead to the development of diabetes-related complications has been the availability of appropriate in vivo models to test each independently. To define the role of glucose delivery to the heart in the regulation of mitochondrial function we have developed a mouse model for inducible cardiomyocyte-specific expression of the glucose transporter, GLUT4. Thus allowing us to directly test the role that cardiomyocyte glucose delivery plays in the healthy and diseased heart. Our preliminary data define a model whereby increased glucose delivery in the basal state enhances glucose utilization. In stark contrast, increased glucose delivery in the presence of hyperglycemia accelerates the development of mitochondrial dysfunction. The long-term goal of my research is to determine the mechanisms controlling mitochondrial metabolic function in the heart. In this proposal, we will start by investigating the role of glucose-mediated mitochondrial regulation by examining glucose-delivery regulated post-translational modification of mitochondrial proteins (Aim 1) and epigenetic control of oxidative phosphorylation (OXPHOS) gene expression (Aim 2). The latter process has recently received significant attention for its contribution to "glycemic memory", defined as the impact that antecedent glucose concentrations have on persistently increasing the risk of diabetic complications independently of current levels of glycemic control. For Specific Aim 1, we will determine the mitochondrial proteins that are modified by the post-translational modification O-linked GlcNAcylation, which is increased with diabetes, and begin to explore the functional consequences of glucose delivery on mitochondrial oxidative capacity and enzymatic function. Studies outlined in Aim 2, will define the role of epigenetic modifications associated with changes in OXPHOS gene expression that are uniquely regulated by glucose. The initial K99 phase of this proposal will facilitate training in aspects of proteomics (2D-PAGE and mass spectroscopy) and epigenetics (histone modifications and DNA methylation). This additional training will provide me with the knowledge and skill set to independently carry out my immediate short-term goal of finding a tenure-track position (R00 phase), necessary to complete the proposal's aims and pursue my interests in defining molecular mechanisms of cardiac dysfunction. Collectively, the completion of these studies will provide fundamental insights into the mechanistic basis for glucose in the development of diabetic cardiomyopathy and mitochondrial dysfunction.