Regulatory Mechanisms of Insulin Secretion

描述（由申请人提供）：糖尿病引起的持续高血糖会对许多器官和组织造成灾难性的损害。一种新兴观点关注的是餐后血糖升高。这些血糖水平可能非常高，峰值浓度比更常见的空腹血糖水平更能预测糖尿病的终末器官损伤。复杂的生理机制专门处理餐后葡萄糖负荷，这些机制的崩溃导致糖尿病。本研究的长期目标是了解葡萄糖刺激胰岛细胞分泌胰岛素的餐后调节。葡萄糖激酶（Glucokinase， GK）决定胰岛素分泌的速率，最近有人提出通过与一氧化氮合酶（nitric oxide synthase， NOS）的相互作用和与一氧化氮的反应对GK进行急性翻译后调控。然而，控制GK与NOS相互作用的机制以及一氧化氮调节GK的生理作用尚不清楚。特异性目标1将量化亚硝基化对GK动力学的影响。Specific Aim 2将使用结构域交换策略来确定GK中与NOS形成复合物所必需的序列元件。Specific Aim 3将确定用于控制分泌颗粒上GK激活的细胞机制，Specific Aim 4将验证NOS对GK的调节被用于通过已知的餐后肠促胰岛素激素（胰高血糖素样肽1）积极调节葡萄糖刺激的胰岛素分泌的假设。这些研究将使用生化方法和荧光成像技术来完成。这项研究将进一步了解营养刺激胰岛素分泌的调节机制，尤其与了解糖尿病的发病机制有关，因为胰岛素分泌功能障碍是与2型糖尿病相关的中心异常之一。公共卫生相关性：胰岛素是胰腺在血糖水平升高时分泌的，分泌反应的强度由激素控制。这项研究将收集与激素控制胰岛素分泌速率的机制有关的信息，并确定特定机制的功能障碍对特定遗传型糖尿病的影响程度。

DESCRIPTION (provided by applicant): Sustained hyperglycemia from diabetes causes catastrophic damage to many organs and tissues. An emerging point of view is focused on the rise in blood glucose following a meal. These blood glucose levels can be very high, and the peak concentration is more predictive of end organ damage in diabetes than the more commonly measured fasting glucose levels. Complex physiological mechanisms exist to specifically handle the post-meal glucose load, and a breakdown in these mechanisms causes diabetes. The long term goal of this study is to understand the post-meal regulation of glucose stimulated insulin secretion from pancreatic beta-islet cells. Glucokinase (GK) sets the rate of insulin secretion, and acute post-translational regulation of GK through interaction with nitric oxide synthase (NOS) and reaction with nitric oxide have recently been proposed. However, the mechanisms that control GK interaction with NOS and the physiological role of GK regulation by nitric oxide are not understood. Specific Aim 1 will quantify the effect of nitrosylation on GK kinetics. Specific Aim 2 will use a domain swapping strategy to identify the sequence elements in GK essential to complex formation with NOS. Specific Aim 3 will identify cellular mechanisms used to control GK activation on secretory granules and Specific Aim 4 will test the hypothesis that regulation of GK by NOS is utilized for positive regulation of glucose-stimulated insulin secretion by a known post-meal incretin hormone, glucagon-like peptide 1. These studies will be accomplished using biochemical methods and fluorescence imaging techniques. This research will further understanding of the mechanisms that regulate nutrient-stimulated insulin secretion and are particularly relevant to understanding the pathogenesis of diabetes, since dysfunctional insulin secretion is one of the central abnormalities associated with type 2 diabetes. PUBLIC HEALTH RELEVANCE: Insulin is secreted from the pancreas in response to rising blood glucose levels, and the strength of the secretory response is controlled by hormones. This study will gather information relating to the mechanisms that hormones use to control the rate of insulin secretion, and determine the extent that dysfunction of a particular mechanism contributes to a specific genetic type of diabetes.