Mechanisms of Myocardial Ischemic Injury in Diabetes

这项建议的总体目标是阐明高血糖升高的机制。 降低心血管发病率和死亡率的心肌缺血和再灌注损伤 在糖尿病和高血糖患者中。受损的一氧化氮(NO‘)信号被认为起着关键作用 糖尿病、高血糖和内皮型一氧化氮在心血管疾病发病机制中的作用 一氧化氮合酶(ENOS)的功能是一个关键因素。目前的提案将检验总体假设 高血糖通过以下途径损害心脏保护信号转导机制 减弱热休克(HSP)90/eNOS的相互作用 氮物种和四氢生物蝶呤(BH4)。在具体目标1中，我们将评估假设 高血糖剂量依赖性地损害eNOS偶联，并导致eNOS依赖性降低 HSP90/eNOS伴侣蛋白和BH4辅助因子对NO‘和超氧阴离子(O2’~)的调节作用 在兔体内和体外血管内皮细胞和心肌细胞中的利用度。我们将解决 高血糖诱导的过氧亚硝酸盐(ONOO“)通过以下途径损害HSP90/eNOS的假说 降低磷酸酪氨酸-HSP90，升高硝基酪氨酸-HSP90；降低BH4。最后， 我们将评估这一假说，即高血糖通过减弱 HSP90/eNOS的相互作用和降低BH4在体内的可用性。这些实验将提供 热休克蛋白90和高血糖通过调节心肌保护作用的新机制信息 蛋白质-蛋白质相互作用和改变自由基的形成使用集成的细胞，分子和 药理学方法。在具体目标2中，我们将解决以下假设： 含磷酸酪氨酸磷酸酶抑制剂的HSP90上的磷酸酪氨酸；提高BH4的利用率 外源性BH4或其代谢前体Sepiapterin；以及新型载脂蛋白A-1减轻氧化应激 模拟D4-F增强HSP90/eNOS结合，恢复体外高血糖时eNOS偶联 和活体内；并恢复对心肌梗死的保护 高血糖通过热休克蛋白90介导的途径。这些实验将阐明一个新的角色 HSP90在心脏保护期间，并将确定潜在的新的治疗靶点，用于治疗 糖尿病和高血糖。 平淡描述：糖尿病患者血糖升高会增加患心脏病的风险 袭击和死亡。拟议的研究将评估热休克蛋白(HSP)90促进 抵抗心脏损伤；将确定血糖对HSP90影响的不利影响：并将 确定潜在的糖尿病治疗新策略。

The overall objective of this proposal is to elucidate the mechanisms whereby hyperglycemia increases myocardial ischemia and reperfusion injury with the goal of reducing cardiovascular morbidity and mortality in patients with diabetes and hyperglycemia. Impaired nitric oxide (NO') signaling is believed to play a key role in the pathogenesis of cardiovascular disease during diabetes and hyperglycemia and endothelial nitric oxide synthase (eNOS) function is a critical factor. Thecurrent proposal will test the overall hypothesis that hyperglycemia impairs cardioprotective signal transduction mechanisms in the heart by attenuating heat shock (HSP)90/eNOS interactions through apathway involving reactive oxygen and nitrogen species and tetrahydrobiopterin (BH4). During Specific Aim 1, we will evaluate the hypotheses that hyperglycemia dose-dependently impairs eNOS coupling and results in eNOS-dependent decreases in NO' and increases in superoxide anion (O2'~) by modulation of HSP90/eNOS chaperone and BH4 co-factor availability in rabbits in vivo and in endothelial cells and cardiomyocytes in vitro. We will address the hypotheses that hyperglycemia-induced formation of peroxynitrite (ONOO") impairs HSP90/eNOS by decreasing phosphotyrosine-HSP90 and increasing nitrotyrosine-HSP90; and by decreasing BH4. Finally, we will evaluate the hypothesis that hyperglycemia blocks ischemic preconditioning (IPC) by attenuating HSP90/eNOS interactions and by decreasing the availability of BH4 in vivo. These experiments will provide novel mechanistic information on the role of HSP90 and hyperglycemia to modulate cardioprotection through protein-protein interactions and altered radical formation using an integrated cellular, molecular and pharmacological approach. During Specific Aim 2, we will address the hypotheses that increasing phosphotyrosine on HSP90 with a phosphotyrosine phosphatase inhibitor; increasing BH4 availability with exogenous BH4 or its metabolic precursor sepiapterin; and decreasing oxidant stress with a novel apo A-1 mimetic D4-F will enhance HSP90 /eNOS association; restore eNOS coupling during hyperglycemia in vitro and in vivo; and restore protection against myocardial infarction produced by IPC in the presence of hyperglycemia through an HSP90-mediated pathway. These experiments will elucidate a novel role for HSP90 during cardioprotection and will confirm potential new therapeutic targets for the treatment of diabetes and hyperglycemia. Lay description: Increases in blood sugar that occur in individuals with diabetes increase the risk of heart attack and death. Theproposed research will evaluate the role of heat shock protein (HSP)90 to promote resistance to heart injury; will determine the adverse effects of blood sugar to impair HSP90 effects: and will identify potential new treatment strategies for diabetes.