Regulatory Mechanisms of Insulin Secretion

描述(由申请人提供)：2型糖尿病的进展与胰岛β细胞无法补偿外周胰岛素抵抗有关。血糖敏感度的丧失，特别是在餐后血糖急剧上升期间，与糖尿病期间的外周组织损伤密切相关。然而，2型糖尿病期间β细胞葡萄糖感应缺陷的分子机制还不是很清楚。这项建议寻求有关葡萄糖激酶调节的关键信息，葡萄糖激酶是胰岛素分泌的β细胞中的葡萄糖感应蛋白。前一个资助期的工作重点是通过与一氧化氮的化学反应激活葡糖激酶的荷尔蒙。这些研究揭示了葡萄糖激酶调节缺陷与人类糖尿病的一种遗传形式之间的重要新联系。尽管如此，关于葡萄糖激酶激活的机制和糖尿病相关细胞应激对葡萄糖激酶功能的影响的主要问题仍然存在。提出了三个目标。目的1将利用一种新开发的葡糖激酶生物传感器来揭示一氧化氮激活细胞与其分子结构所暗示的潜在生化状态之间的联系。目的2将重点了解导致葡萄糖激酶与一氧化氮合酶结合的分子机制，一氧化氮合酶是葡萄糖激酶激活细胞所需的关键相互作用。这一目的的实验还将揭示葡萄糖激酶调节缺陷是否可以解释NOS1AP基因突变与人类糖尿病的关联。目标3将侧重于糖尿病相关细胞应激对葡萄糖激活酶活性的影响。我们的初步数据显示，内质网功能受损会扰乱葡糖激酶的调节。计划中的研究试图找出这种干扰背后的机制，并测试与饮食相关的肥胖是否同样会扰乱葡萄糖激酶的调节。如果是这样的话，这些研究将为2型糖尿病期间血糖感应受阻提供一个分子解释。综上所述，这些研究有可能统一葡萄糖激酶功能的细胞和生化模型，识别新的葡萄糖激酶活性的分子调节因子，并将引导人们对2型糖尿病中观察到的ç细胞葡萄糖感知缺陷的分子原因产生新的想法。了解导致2型糖尿病恶化的分子事件对于设计针对β细胞葡萄糖感应的新疗法至关重要。

DESCRIPTION (provided by applicant): Progression of type 2 diabetes mellitus tracks with the failure of pancreatic beta cells to compensate for peripheral insulin resistance. Loss of glucose sensitivity, particularly during the sharp rise in blood glucose that follows a meal, is strongly associated with peripheral tissue damage during diabetes. Yet the molecular mechanisms underlying defects in beta-cell glucose sensing during type 2 diabetes are not well understood. This proposal seeks critical information regarding the regulation of glucokinase, which is the glucose sensing protein in insulin-secreting beta cells. Work in the previous funding period focused on hormonal activation of glucokinase through chemical reaction with nitric oxide. These studies revealed important new connections between defects in glucokinase regulation and a genetic form of human diabetes. Even so, major questions remain concerning the mechanism of glucokinase activation and the impact of diabetes-related cell stress on glucokinase function. Three aims are proposed. Aim 1 will utilize a newly developed glucokinase biosensor to reveal the connection between cellular activation by nitric oxide and the underlying biochemical states suggested by its molecular structure. Aim 2 will focus on understanding the molecular mechanism that leads to glucokinase association with nitric oxide synthase, which is a critical interaction required for cellular activation of glucokinase. Experiments in this aim wil also reveal whether defects in glucokinase regulation may explain the association of NOS1AP gene mutations with human diabetes. Aim 3 will focus on the impact of diabetes-related cell stress on glucokinase activation. Our preliminary data show that impaired endoplasmic reticulum function disrupts glucokinase regulation. The planned studies seek to identify the mechanism behind this disruption, and test whether diet-related obesity can similarly disrupt glucokinase regulation. If so, these studies will provide a molecular explanation for inhibited glucose sensing during type 2 diabetes. In summary, these studies have the potential to unify cellular and biochemical models of glucokinase function, identify new molecular regulators of glucokinase activity, and will lead to new ideas about the molecular causes underlying the deficit in ß-cell glucose sensing observed in type 2 diabetes mellitus. Understanding the molecular events that worsen type 2 diabetes mellitus is vital for designing new therapies that target beta-cell glucose sensing.