AMPK Endothelial Cell Dysfunction and the Metabolic Syndrome (PROGRAM PROJECT)

代谢综合征在临床上被定义为一种以血脂异常、高血压、中枢性肥胖、高血糖为特征的疾病，并易患过早动脉粥样硬化性心血管疾病和2型糖尿病。此外，它还与微血管稀疏和血管生成受损有关。在人类和实验动物中，代谢综合征通常伴随着并先于胰岛素抵抗、脂质异常和促炎状态。我们和其他人提出，这些异常可能是燃料感应酶amp活化蛋白激酶（AMPK）失调的结果。这个项目将重点关注内皮细胞，它通常被认为是在动脉粥样硬化和血管生成受损过程中第一个发生改变的血管细胞。将测试两个主要假设：1)与代谢综合征相关的血管异常部分是由内皮细胞和外周组织中AMPK的失调（基础活性降低或激活受损）引起的；2)这种失调是SIRT1/LKB1信号机制受损的结果，我们已经证明SIRT1/LKB1信号机制在各种培养细胞和体内肝脏中调节AMPK活性（见项目1）。这三个项目将分别和共同表征培养血管内皮细胞中SIRT1/LKB1/AMPK的机制，并确定其激活和抑制对葡萄糖、FFA和TNF的促动脉粥样硬化作用的影响。（项目1,2）和血管生成对缺血的反应（项目3）。我们还将探讨氧化应激导致SIRT1翻译后修饰的假设，这种修饰可以通过AMPK激活来阻止（项目2,1）。最后，我们将开发内皮细胞特异性缺失SIRT1或LKB1 （Core B）的转基因小鼠。然后，我们将在对照组小鼠和喂食高脂肪/高糖饮食的小鼠中评估这些缺失对肌肉毛细血管（项目3和1）和主动脉粥样硬化变化（项目2）的影响。此外，我们将在这些小鼠中评估运动的抗动脉粥样硬化和促血管生成作用（项目1-3）。由于研究的互动性和实验模型的使用是由多个研究者最有效地研究的，因此申请项目资助。代谢综合征影响着美国超过6000万20岁以上的人，是一个主要的公共卫生问题。所提出的研究将对早期动脉粥样硬化和与此相关的血管生成受损的生物学基础产生新的见解，并为预防这些疾病提供新的治疗靶点。

The metabolic syndrome has been defined clinically as a disorder characterized by dyslipidemia, hypertension, central obesity, hyperglycemia and a predisposition to premature atherosclerotic cardiovascular disease and type 2 diabetes. In addition it is associated with microvascular rarefaction and impaired angiogenesis. In both humans and experimental animals the metabolic syndrome is typically accompanied and preceded by insulin resistance, lipid abnormalities and a proinflammatory state. We and others have proposed that these abnormalities could be the result of dysregulation of the fuel-sensing enzyme AMP-activated protein kinase (AMPK). This program will focus on the endothelium, which is generally believed to be the first vascular cell altered during both atherogenesis and impaired angiogenesis. Two major hypotheses will be tested: 1) that the vascular abnormalities associated with the metabolic syndrome are caused in part by dysregulation of AMPK (decreased basal activity or impaired activation) in the endothelial cell as well as peripheral tissues and 2) that such dysregulation is the result of impairment of a SIRT1/LKB1 signaling mechanism that we have demonstrated regulates AMPK activity in various cultured cells and in the liver in vivo (See Project 1). The three projects will individually and collectively characterize the SIRT1/LKB1/AMPK mechanism in cultured vascular endothelial cells and determine the effects of its activation and inhibition on the proatherogenic effects of glucose, FFA and TNF? (Projects 1, 2) and the angiogenic response to ischemia (Project 3). We will also explore the hypothesis that oxidative stress causes post-translational modifications of SIRT1 that can be prevented by AMPK activation (Projects 2, 1). Finally, we will develop transgenic mice with an endothelial cell specific deletion of SIRT1 or LKB1 (Core B). We will then assess the effect of these deletions on muscle capillarity (Projects 3 and 1) and atherogenic changes in the aorta (Project 2) in control mice and mice fed a high-fat/high sucrose diet. In addition, we will assess the anti-atherogenic and pro-angiogenic effects of exercise in these mice (Projects 1-3). A program project grant is requested because of the interactive nature of the research and the use of experimental models that are most effectively studied by multiple investigators. The metabolic syndrome affects over 60,000,000 people in the U.S. over the age of 20 and is a major public health problem. The proposed studies should both yield novel insights into the biological bases for the premature atherosclerosis and impaired angiogenesis associated with this entity and suggest new therapeutic targets for their prevention.