AMP-activated kinase in diabetic complications

描述（由申请人提供）：糖尿病及其相关并发症是发达国家的主要健康问题。糖尿病患者患心血管疾病（CVD）的可能性是普通人群的2- 4倍。近年来，糖尿病的一个明显特征是过度氧化应激。在这里提出的初步数据中，我们发现高血糖症和游离脂肪酸（FFA），I型和II型糖尿病的两个标志，在内皮细胞中产生氧化应激。这些导致脂质过氧化、前列环素合酶（PGIS）的酪氨酸硝化、NO生物活性降低、内皮型一氧化氮合酶（eNOS）解偶联和胰岛素抵抗。我们还发现，用AMP激活的激酶（AMPK）激活剂5-氨基-4-咪唑甲酰胺核苷（AICAR）治疗可以防止所有这些事件，包括氧化应激和胰岛素抵抗的增加。该提议的基本前提是AMPK活化可以通过增加线粒体解偶联蛋白（UCP）-2来保护内皮细胞免受高血糖和FFA的不利影响，线粒体解偶联蛋白（UCP）-2导致氧化应激的降低与NO生物活性的增加平行。因此，作为本申请的中心假设，我们提出胰岛素抵抗和糖尿病的血管素质部分是由于高血糖症/FFA诱导的氧化应激和AMPK的代偿性激活。我们的提案的下一部分将确定AMPK激活对氧化应激、内皮功能和胰岛素信号传导的后果，利用AICAR在体外降低葡萄糖和脂肪酸引起的细胞氧化应激和胰岛素抵抗以及在体内糖尿病增强的Apo-E敲除（KO）中的主动脉病变的初步数据。为了实现这一目标，我们建议研究1）。确定通过多种方法（药理学和分子生物学方法）激活AMPK是否降低氧化应激和胰岛素抵抗，并评估其如何起作用，以及2）。确定AMPK依赖的氧化应激和内皮功能障碍的减少是否在体内糖尿病中起作用。这种体外和体内技术的强大组合将提供关于与糖尿病相关的代谢应激如何引起内皮损伤的新信息。他们还应该深入了解内皮细胞如何试图保护自己免受这些压力，以及AMPK是否是糖尿病治疗的潜在靶点。

DESCRIPTION (provided by applicant): Diabetes mellitus and its associated complications are a major health problem in the developed world. Diabetics are 2- to 4-times more likely to have cardiovascular diseases (CVD) than general population. One feature of diabetes that has become apparent in recent years is excess oxidant stress. In preliminary data presented here, we have found that hyperglycemia and free fatty acids (FFA), two hallmarks of type I and type II diabetes, impart an oxidant stress in endothelial cells. These results in lipid peroxidation, tyrosine nitration of prostacyclin synthase (PGIS), reduced NO bioactivity, endothelial nitric oxide synthase (eNOS) uncoupling, and insulin resistance. We have also found that treatment with the AMP-activated kinase (AMPK) activator, 5-amino-4-imidazole carboxamide riboside (AICAR), prevents all of these events including the increase in oxidant stress and insulin resistance from occurring. A basic premise of this proposal is that AMPK activation could protect the endothelial cell against the adverse effects of hyperglycemia and FFA by increasing mitochondrial uncoupling protein (UCP)-2 that lead to a decrease in oxidant stress in parallel with an increase in NO bioactivity. Therefore, as a central hypothesis of this application, we propose that vascular diathesis of insulin resistance and diabetes is due, in part, from a hyperglycemia/FFA-induced oxidant stress and a compensatory activation of AMPK. The next part of our proposal will determine the consequences of AMPK activation on oxidant stress, endothelial function, and insulin signaling, capitalizing on preliminary data that AICAR reduces both cellular oxidant stress and insulin resistance from glucose and fatty acids in vitro and aortic lesions in Apo-E knockout (KO) enhanced by diabetes in vivo. In order to accomplish this goal, we propose to study 1). To determine if activation of AMPK by a number of means (pharmacological and molecular biological means) reduces oxidant stress and insulin resistance and to evaluate how it works, and 2). To determine if AMPK-dependent reduction in oxidant stress and endothelial dysfunction is operating in diabetes in vivo. This powerful combination of in vitro and in vivo techniques will provide novel information as to how the metabolic stresses associated with diabetes cause damage to the endothelium. They should also yield insights into how endothelium attempts to protect itself against these stresses and whether AMPK is a potential target for therapy for diabetes.