Mechanisms of Myocardial Ischemic Injury in Diabetes

本提案的总体目标是阐明高血糖增加的机制， 心肌缺血和再灌注损伤，目的是降低心血管发病率和死亡率 糖尿病和高血糖症患者。一氧化氮（NO）信号传导受损被认为是 糖尿病、高血糖和内皮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。当前的提案将检验总体假设 高血糖症损害心脏中的心脏保护信号转导机制， 通过涉及活性氧的途径减弱热休克（HSP 90）/eNOS相互作用， 氮物种和四氢生物蝶呤（BH 4）。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，导致eNOS依赖性降低， HSP 90/eNOS分子伴侣和BH 4辅因子的调节可使NO'和超氧阴离子（O2'~）增加 在家兔体内以及在体外内皮细胞和心肌细胞中的可用性。我们将解决 假设高血糖诱导的过氧亚硝酸盐（ONOO”）的形成通过以下途径损害HSP 90/eNOS 减少磷酸酪氨酸-HSP 90并增加硝基酪氨酸-HSP 90;以及减少BH 4。最后， 我们将评估高血糖通过减弱缺血预处理（IPC）的作用而阻断IPC的假设， HSP 90/eNOS相互作用和降低体内BH 4的可用性。这些实验将提供 HSP 90和高血糖通过调节心脏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，使用一个集成的细胞，分子和 药理学方法在具体目标2中，我们将讨论增加的假设 用磷酸酪氨酸磷酸酶抑制剂对HSP 90的磷酸酪氨酸;用磷酸酪氨酸磷酸酶抑制剂增加BH 4的可用性， 外源性BH 4或其代谢前体sepiapterin;以及用新的apo A-1降低氧化应激 模拟D4-F可增强HSP 90/eNOS的结合，恢复高血糖时eNOS的偶联 和体内;并恢复IPC在存在下产生的心肌梗死保护作用 通过HSP 90介导的途径降低高血糖。这些实验将阐明一个新的作用， HSP 90在心脏保护中的作用，并将确认治疗心肌梗死的潜在新治疗靶点。 糖尿病和高血糖症。 简单描述：糖尿病患者血糖升高会增加心脏病的风险。 攻击和死亡。这项研究将评估热休克蛋白（HSP）90促进 抗心脏损伤;将确定血糖的不利影响，以削弱HSP 90的影响：并将 确定糖尿病潜在的新治疗策略。

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.