The Role of RAGE in Diabetes and Myocardial Infarction.

描述(由申请人提供)：心肌梗死是发病率和死亡率的主要因素，糖尿病会加剧心肌梗死。然而，糖尿病患者心脏损伤易感性增加的机制尚不清楚。我们实验室以前的研究已经揭示了晚期糖基化终产物受体(RAGE)在心肌梗死中的核心作用，因为与野生型相比，RAGE的全局缺失可以减少心肌缺血/再灌注(I/R)后48小时的心肌坏死，增加功能恢复和ATP的保存。RAGE在多种影响心肌对I/R损伤反应的细胞类型中表达，如单核/巨噬细胞、内皮细胞和心肌细胞。我们发现RAGE有助于I/R引起的氧化应激，并影响伴随心脏损伤的线粒体功能障碍。RAGE的配体在糖尿病条件下和I/R后增加，导致下游信号增加。我们的实验室已经发现RAGE胞质结构域与Diaphanous-1(MDIA-1)相互作用，Diaphanous-1(MDIA-1)是Forin家族的成员，也是Rho GTP酶的效应因子。这项研究的总体目标是研究心肌细胞中RAGE/mDia1信号对I/R损伤的反应。我们预测，心肌细胞特异性RAGE和MDIA在I/R后在小鼠心脏中高度上调，发出心肌破坏性代谢后果的信号，从而引发线粒体功能障碍。理想情况下，这项研究将转化为改善经历过心肌梗死的糖尿病患者的预后。为了实现这一目标，我们将在RAGE和mDia1表达存在遗传变异的糖尿病和非糖尿病小鼠品系中使用左前降支冠状动脉结扎模型。我们将通过超声心动图评估遗传劳损引起的I/R所致左心功能不全的差异。此外，我们还将对从野生型和转基因小鼠分离的心肌细胞进行更有针对性的缺氧/复氧研究。我们将使用体外灌流心脏模型来评估线粒体功能。我提出的研究将提供信息，以指导未来对发生心肌梗死的糖尿病患者的治疗，并防止进一步的并发症发展。此外，这个项目将帮助我实现我的培训目标，即1)表征和使用转基因小鼠来测试RAGE/mDia1信号导致心肌破坏性代谢后果的假设，2)使用原代心肌细胞来研究相关机制，3)使用体外缺血/再灌流心脏模型来解决这一假设，4)掌握使用生理相关模型来评估I/R损伤。这项研究的成功完成将增加我的知识、技能和潜力，以实现我成为心血管疾病独立研究人员的最终目标。 公共卫生相关性：糖尿病患者的高死亡率和发病率可部分归因于心肌梗死后对损伤的易感性增加；然而，这种现象背后的机制尚不清楚。该项目将研究晚期糖基化终产物受体的信号机制，该受体已被确定为心肌对缺血/再灌注损伤反应的中心介质。该项目的成功完成将确定治疗心肌梗死的糖尿病患者的潜在治疗目标，同时为我未来成为心血管疾病领域的独立研究人员的职业目标做好准备。

DESCRIPTION (provided by applicant): Myocardial infarction is a major contributor to morbidity and mortality and is exacerbated by diabetes. However, the mechanisms underlying this increased susceptibility to cardiac injury in diabetic patients are not well understood. Previous studies by our laboratory have revealed a central role for the receptor for advanced glycation end-products (RAGE) in myocardial infarction, as global deletion of RAGE resulted in decreased myocardial necrosis, increased functional recovery and preservation of ATP compared to wild-type littermates 48 hours after ischemia/reperfusion (I/R). RAGE is expressed in multiple cell types that impact the myocardial response to I/R injury, such as monocytes/macrophages, endothelial cells, and cardiomyocytes. We have uncovered that RAGE contributes to oxidative stress consequent to I/R and influences mitochondrial dysfunction that accompanies injury to the heart. Ligands for RAGE are increased under diabetic conditions and after I/R, leading to increased downstream signaling. Our laboratory has discovered that the RAGE cytoplasmic domain interacts with diaphanous-1 (mDia-1), a member of the formin family, and an effector of Rho GTPases. The overall goal of the proposed research is to investigate RAGE/mDia1 signaling in cardiomyocytes in response to I/R injury. We predict that cardiomyocyte-specific RAGE and mDia, both highly upregulated in the murine heart after I/R, signal devastating metabolic consequences in the myocardium, which trigger mitochondrial dysfunction. Ideally, this research will translate into an improved prognosis for diabetic patients who have undergone myocardial infarction. To meet this goal, we will use the left anterior descending coronary artery ligation model of I/R in strains of diabetic and non- diabetic mice with genetic variations in RAGE and mDia1 expression. We will assess differences in I/R-induced left ventricular dysfunction due to genetic strain by echocardiography. Additionally, we will perform more targeted studies of hypoxia/reoxygenation in cardiomyocytes isolated from wild type and transgenic mice. We will use the ex vivo perfused heart model to assess mitochondrial function. My proposed studies will provide information to guide future efforts for the treatment of diabetic patients who have undergone myocardial infarction and prevent the development of further complications. In addition, this project will help me accomplish my training goals, which are to 1) characterize and use transgenic mice to test the hypothesis that RAGE/mDia1 signaling lead to devastating metabolic consequences in the myocardium, 2) use primary cardiomyocytes to address the mechanisms involved, 3) employ the ex vivo perfused heart model of ischemia/reperfusion to address the hypothesis, and 4) master the use of physiologically relevant models to assess I/R injury. The successful completion of this research will increase my knowledge, skill set, and potential to achieve my ultimate goal of becoming an independent researcher in cardiovascular disease. PUBLIC HEALTH RELEVANCE: The high rate of mortality and morbidity in diabetic patients can be partially attributed to an increased susceptibility to injury in response to myocardial infarction; however, the mechanisms behind this phenomenon are unknown. This project will investigate the signaling mechanisms of the receptor for advanced glycation end products, which has been identified as a central mediator of the myocardial response to ischemia/reperfusion injury. The successful completion of this project will identify potential therapeutic targets for the treatment of diabetic patients who have undergone myocardial infarction while simultaneously preparing me for a future career goal of being an independent researcher in the field of cardiovascular disease.