Oxidant stress and diabetic endothelial dysfunction

氧化应激与糖尿病内皮功能障碍

• 批准号: 6865275
• 负责人: MING-HUI ZOU
• 金额: $ 36.63万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6865275
• 关键词: apoptosis; biological signal transduction; cell adhesion molecules; cytochrome P450; diabetic angiopathy; diacylglycerols; eicosanoid receptor; free fatty acids; genetically modified animals; human tissue; hyperglycemia; hyperlipidemia; insulin sensitivity /resistance; laboratory mouse; nitration; oxidative stress; peroxynitrites; protein kinase C; receptor expression; streptozotocin; superoxide dismutase; superoxides; thromboxanes

DESCRIPTION (provided by applicant): Endothelial dysfunction represents a common pathogenic framework that contributes in both types of diabetes mellitus to the development of vascular disease that affects micro- and macro- blood vessels. Recent evidence indicates that the endothelial dysfunction associated with diabetes is the local formation of oxidants and free radicals. However, the mechanisms by which diabetes increases oxidant stress, and those by which oxidant stress modifies endothelial function are poorly understood. Our preliminary results have established new insights into how hyperglycemia and/or hyperlipidemia increase oxidant stress. Exposure of cultured human aortic endothelial cells to elevated glucose for 3-10 days increases the production of superoxide anion (O2), which reacts with nitric oxide (NO) to generate a potent oxidant, ONOO. Increased levels of its reaction product with tyrosine, 3-nitrotyrosine, are found in the cells. Although the function of many proteins may be affected, we have found that prostacyclin synthase (PGIS) is particularly susceptible to tyrosine nitration in human aortic endothelial cells exposed to elevated glucose. The levels of nitrated PGIS increase and its activity decreases. This may not only explain why diabetes decreases levels of PGI2, but also why increases have been noted in the PGI2 precursor, PGH2, which acts upon thromboxane A2 receptor (termed TP-receptor, TPr). Our preliminary studies have shown that exposure of human aortic endothelial cell to elevated glucose enhances adhesion molecular expression, endothelial cell apoptosis, inhibits Akt and insulin signaling by mechanisms which depend on ONOO- and TPr activation. Our central hypothesis is that diabetes via hyperglycemia/hyperlipidemia increases the generation of O2 and then ONOO, resulting in PGIS nitration and TPr stimulation and insulin resistance. The aims of the proposed studies are: 1). To determine the role(s) of ONOO-triggered PGIS nitration and TPr activation in enhancing endothelial cell adhesion molecule expression and apoptosis in the HAEC cells exposed to hyperglycemia/FFAs and to determine if PGIS is resistant to nitration caused by the streptozotocin-indued diabetes in the transgenic mice (hSOD +/+) or knockout mice (eNOS -/-, gp91phox-/-). 2). To establish the links between cellular oxidant stress, PGIS nitration and TPr activation, and impaired insulin signaling in cells exposed to hyperglycemia/FFAs. Based on the results, we will assess which of these alterations is likely to be pathogenetic for cell damage. These studies will provide novel information as to how the metabolic stress associated with diabetes cause damage to the endothelium and how endothelial cell attempts to protect itself against these stresses and whether ONOO or TPr are potential targets for therapy.

描述(申请人提供)：内皮功能障碍是一种常见的致病框架，在这两种类型的糖尿病中都会导致影响微血管和大血管的血管疾病的发展。最近的证据表明，与糖尿病相关的内皮功能障碍是局部氧化剂和自由基的形成。然而，糖尿病增加氧化应激的机制以及氧化应激改变内皮功能的机制还知之甚少。我们的初步结果为高血糖和/或高脂血症如何增加氧化应激建立了新的见解。培养的人主动脉内皮细胞暴露于高糖3-10天会增加超氧阴离子(O2)的产生，超氧阴离子(O2)与一氧化氮(NO)反应生成一种强有力的氧化剂ONOO。在细胞中发现其与酪氨酸的反应产物3-硝基酪氨酸的水平增加。虽然许多蛋白质的功能可能会受到影响，但我们发现，在高糖暴露下的人主动脉内皮细胞中，前列环素合成酶(PGIs)对酪氨酸硝化特别敏感。硝化前列腺素I水平升高，活性降低。这可能不仅解释了为什么糖尿病降低了PGI2水平，而且也解释了为什么作用于血栓素A2受体(称为TP受体，TPR)的PGI2前体PGH2水平增加。我们的初步研究表明，人主动脉内皮细胞暴露于高糖环境中，可促进黏附分子表达，促进内皮细胞凋亡，抑制Akt和胰岛素信号转导，其机制依赖于ONOO-1和TPR的激活。我们的中心假设是，糖尿病通过高血糖/高脂血症增加O2的产生，然后ONOO的产生，导致PGIs硝化和TPR刺激和胰岛素抵抗。拟议研究的目的是：1)。探讨ONOO触发的PGIs硝化和TPR激活在高血糖/游离脂肪酸诱导的HAEC细胞内皮细胞黏附分子表达和细胞凋亡中的作用，以及在转基因小鼠(hSOD+/+)和基因敲除小鼠(eNOS-/-，gp91Phox-/-)中，PGIS对链脲佐菌素诱导的糖尿病所致硝化反应是否具有抵抗作用。2)。建立细胞氧化应激、PGIS硝化和TPR激活之间的联系，以及暴露于高血糖/游离脂肪酸的细胞胰岛素信号受损之间的联系。基于这些结果，我们将评估这些变化中的哪些可能是细胞损伤的致病因素。这些研究将提供新的信息，如与糖尿病相关的代谢应激如何导致内皮损伤，内皮细胞如何试图保护自己免受这些应激的影响，以及ONOO或TPR是否为潜在的治疗靶点。