AMPK and Mechanisms of Glucose Toxicity

在糖尿病患者和实验动物中，持续高血糖导致胰岛素抵抗 肝脏和肌肉都有。我们在许多模型中获得的数据表明，这种葡萄糖诱导 胰岛素抵抗与AMP活化蛋白激酶(AMPK)/丙二酰辅酶A燃料调节失调有关 感应和信号网络(AMPK活性降低和/或丙二酰辅酶A浓度增加)。 拟议的研究将在其中两个模型中验证这一假设，培养的肝细胞暴露于 高环境葡萄糖浓度(目标1)和葡萄糖输注大鼠(目标3)，在这两种情况下，我们都有 观察到上述AMPK和丙二酰辅酶A的变化，并在研究中发现能力受损 来激活Akt。此外，我们将尝试开发一个基于细胞的系统来测试这一点 使用C2C12细胞的肌肉假说(目标2)。我们将确定这些模型中的每个模型如何变化 在AMPK中，与胰岛素信号转导受损(Akt，IRS-PY)有关，脂代谢产物的改变 (丙二酰辅酶A、DAG、LCCoA)和推测的下游致病事件(例如，PKC、IKKB-NF*B 激活)。此外，使用RNAi沉默、病毒构建和/或药理学试剂作为工具，我们 将确定AMPK和丙二酰辅酶A的变化是否起到因果作用。最后，我们将探索 葡萄糖输注大鼠AMPK活性降低的可能机制。 这些研究将对AMPK/丙二酰辅酶A调节失调的假设进行严格的检验 Network既是葡萄糖诱导的胰岛素抵抗的原因之一，也是其治疗的靶点。他们会 也为理解胰岛素的发病机制和治疗提供了一个潜在的新框架。 耐药性，这是一个先于2型糖尿病、早发冠心病、NAFLD/NASH和 其他与代谢综合征相关的疾病。因此，它们可能对以下方面产生重要影响 公共卫生。

In patients with diabetes and experimental animals sustained hyperglycemia leads to insulin resistance in both liver and muscle. Data obtained by us in a number of models suggest that such glucose-induced insulin resistance is related to dysregulation of the AMP-activated protein kinase (AMPK)/malonyl CoAfuel sensing and signaling network (diminished AMPK activity and/or an increase in malonyl CoA concentration). The proposed studies will test this hypothesis in two of these models, cultured hepatocytes exposed to a high ambient glucose concentration (Aim 1) and glucose-infused rats (Aim 3), in both of which we have observed the aforementioned changes in AMPK and malonyl CoA, and, where studied, an impaired ability of insulin to activate Akt. In addition, we will attempt to develop a cell-based system for testing this hypothesis in muscle using C2C12 cells (Aim 2). We will determine in each of these models how changes in AMPK relate temporally to impaired insulin signaling (Akt, IRS-PY), alterations in lipid metabolites (malonyl CoA, DAG, LCCoA) and putative downstream pathogenetic events (e.g., PKC, IKKB-NF*B activation). In addition, using RNAi silencing, viral constructs and/or pharmacological agents as tools, we will determine whether the changes in AMPK and malonyl CoA play a causal role. Finally, we will explore possible mechanisms for the decrease in AMPK activity in the glucose-infused rats. These studies will provide a rigorous test of the hypothesis that dysregulation of the AMPK/malonyl CoA network can be both a cause of glucose-induced insulin resistance and a target for its therapy. They will also provide a potentially novel framework for understanding the pathogenesis and treatment of insulin resistance, a problem that antedates type 2 diabetes, premature coronary heart disease, NAFLD/NASH and other disorders associated with the metabolic syndrome. Thus, they could have an important impact on public health.