Mitochondrial Dysfunction and Adipose Insulin Resistance

线粒体功能障碍与脂肪胰岛素抵抗 摘要 各种动物、细胞培养和分子研究表明，氧化应激增加和 超氧阴离子和羟基自由基等活性氧物种的积累 到2型糖尿病。虽然多年来一直受到重视，但尚不清楚氧化应激/ROS是否是一种偶然的 或疾病病因中的因果因素。然而，最近的工作利用了各种损失 功能增益分析表明，氧化应激与胰岛素有因果关系 抗药性，但分子机制仍不清楚。此应用程序将配置新的和 来自我们实验室的令人信服的发现，使用动物和细胞培养模型建立了 脂肪细胞抗氧化防御系统与线粒体的分子连锁 功能、氧化磷酸化、信号转导与胰岛素抵抗的发生发展。 我们提出了一个新的假说，该假说得到了来自基因组、蛋白质组、 指向线粒体共价修饰的代谢学和分子分析 具有生物活性脂质的蛋白质和线粒体硫氧还蛋白的氧化是这一过程的中心。 发起这种氧化应激挑战的是描述了肿瘤坏死因子的新发现 (肿瘤坏死因子)依赖的谷胱甘肽S转移酶A4下调为分子奠定了基础 激活c-jun氨基末端激酶(JNK)的一系列事件，JNK是一种已建立的 胰岛素敏感性。此外，我们提出了新的发现，证明了下调 GSTA4不仅是在胰岛素抵抗动物模型中观察到的一个过程，而且还发生在 在肥胖、胰岛素抵抗但不肥胖的胰岛素敏感者中选择性地提供一种 肥胖症与胰岛素抵抗的分子鉴别。此应用程序构建在最近的 在Bernlohr，Griffin和Arriaga实验室获得的在功能上与氧化有关的证据 对胰岛素抵抗的压力。 总之，这些研究导致了我们的中心假设：GSTA4在脑内的表达减少 脂肪细胞导致线粒体蛋白的羧化增加。羧化反应 线粒体蛋白导致TCA循环活性降低，状态3呼吸缺陷 和增加超氧阴离子的产生。线粒体功能障碍与ROS的产生 进而导致硫氧还蛋白2(Trx2)的相对氧化和Trx2-ASK1- 参与胰岛素抵抗的JNK/p38信号系统。为了检验这一假设， 提出了以下四个具体目标： 目的1.鉴定和评价线粒体蛋白质在细胞培养和动物模型中的甲基化作用。 目的2.在细胞培养和动物模型中评估线粒体功能和ROS的产生。 目的3.低脂和高脂饲养的aP2-HA-GSTA4转基因小鼠的建立和鉴定 节食。 目的4.研究Trx2-ASK1-JNK通路对动物胰岛素信号的调节作用 和细胞培养模型。

Mitochondrial Dysfunction and Adipose Insulin Resistance Abstract A variety of animal, cell culture and molecular studies have correlated increased oxidative stress and the accumulation of reactive oxygen species (ROS) such as superoxide anion and hydroxyl radicals to type 2 diabetes. While appreciated for years, it was unclear if oxidative stress / ROS was a casual or causal factor in the etiology of the disease. However, more recent work utilizing a variety of loss and gain of function analyses have indicated that oxidative stress is causally linked to insulin resistance but that the molecular mechanisms remain obscure. This application will profile new and compelling findings from our laboratories using animal and cell culture models that establish a molecular linkage between the antioxidant defense system in adipose cells with mitochondrial function, oxidative phosphorylation, signal transduction and the development of insulin resistance. We present a novel hypothesis supported by preliminary studies from genomic, proteomic, metabolomic and molecular analyses that point toward the covalent modification of mitochondrial proteins with bioactive lipids and the oxidation of mitochondrial thioredoxin as central to the process. Initiating this oxidative stress challenge are new findings that describe the tumor necrosis factor ¿ (TNF¿) dependent down regulation of glutathione S-transferase A4 setting the stage for a molecular cascade of events that activates the c-JUN NH2-terminal kinase (JNK), an established regulator of insulin sensitivity. Moreover, we present new findings that demonstrate that the down regulation of GSTA4 is not merely a process observed in animal models of insulin resistance but also occurs selectively in obese, insulin resistant, but not obese, insulin sensitive humans thereby providing a molecular differentiation between obesity and insulin resistance. This application builds on recent evidence obtained in the Bernlohr, Griffin and Arriaga laboratories that functionally links oxidative stress to insulin resistance. These studies in sum lead to our central hypothesis: decreased expression of GSTA4 in adipocytes leads to increased mitochondrial protein carbonylation. Carbonylation of mitochondrial protein results in decreased TCA cycle activity, defective State 3 respiration and increased superoxide anion production. Mitochondrial dysfunction and ROS production leads in turn to the relative oxidation of Thioredoxin 2 (Trx2) and the activation of Trx2-ASK1- JNK/p38 signaling system contributing to insulin resistance. To test this hypothesis, the following four specific aims are proposed: Aim 1. Identify and evaluate mitochondrial protein carbonylation in cell culture and animal models. Aim 2. Assess mitochondrial function and ROS production in cell culture and animal models. Aim 3. Develop and characterize aP2-HA-GSTA4 transgenic mice maintained on low and high fat diets. Aim 4. Characterize the regulation of insulin signaling by the Trx2-ASK1-JNK pathway in animal and cell culture models.