Glucose/Secreatogogue Metabolism in Pancreatic islets

描述（由申请方提供）：广泛的长期目标是获得有关胰岛素分泌代谢信号的新信息。该项目的直接目的是更好地了解线粒体生物合成途径在胰岛素分泌中的作用。葡萄糖，最有效的胰岛素促分泌素，和所有其他燃料促分泌素通过它们在线粒体中的代谢刺激胰岛素分泌。我们的工作和其他人的工作涉及柠檬酸循环中间体的生物合成（回补）和它们从线粒体到细胞质的出口（回补），在信号胰岛素分泌。目的1是研究回补的潜在产物，并将检验以下假设：所有燃料胰岛素促分泌素的代谢共享涉及线粒体的最终共同途径，并且辨别这些途径将产生关于线粒体因子的新线索，线粒体因子将代谢和胞吐作用偶联。我们将跟进我们实验室最近的一项惊人发现，即柠檬酸盐在提供丙酮酸盐的β细胞线粒体中和提供葡萄糖的完整β细胞中振荡，假设柠檬酸盐可以协调线粒体代谢与整体细胞代谢。计划进行研究以确定除了柠檬酸盐之外的柠檬酸循环中间体是否在完整细胞中振荡，非葡萄糖促分泌素是否引起柠檬酸循环中间体的振荡，以了解线粒体如何变得同步以产生柠檬酸盐振荡，并研究柠檬酸盐振荡的调节。目的2将集中于线粒体产物的某些线粒体外作用，以验证大多数柠檬酸循环中间产物在胰岛素分泌中具有信号作用的假设。在Aim 2A中，小干扰RNA将用于特异性降低某些使用线粒体产物的酶的水平。胰岛素释放的减少将与代谢途径的改变进行比较。在目标2B中，将进行2型糖尿病中β细胞增殖的有限集中研究。

DESCRIPTION (provided by applicant): The broad long-term objective is to obtain new information about the metabolic signals for insulin secretion. The immediate purpose of this project is to gain a better understanding of the role of mitochondrial biosynthetic pathways in insulin secretion. Glucose, the most potent insulin secretagogue, and all other fuel secretagogues stimulate insulin secretion via their metabolism in mitochondria. Our work and that of others has implicated the biosynthesis (anaplerosis) of citric acid cycle intermediates and their export from mitochondria to the cytosol (cataplerosis) in signaling insulin secretion. Aim 1 is to study the potential products of anaplerosis and will test the hypothesis that the metabolism of all fuel insulin secretagogues shares final common pathways involving mitochondria and that discerning these pathways will yield new clues about mitochondrial factors that couple metabolism and exocytosis. We will follow up a recent surprising discovery from our laboratory that citrate oscillates in beta cell mitochondria supplied with pyruvate and in intact beta cells supplied with glucose, it is hypothesized that citrate can coordinate mitochondrial metabolism with overall cellular metabolism. Studies are planned to determine whether citric acid cycle intermediates besides citrate oscillate in intact ceils, whether non-glucose secretagogues cause oscillations in citric acid cycle intermediates, to learn how mitochondria become synchronized to produce citrate oscillations, and to investigate the regulation of citrate oscillations. Aim 2 will focus on certain extramitochondrial actions of mitochonddal products to test the hypothesis that most citric acid cycle intermediates have signaling roles in insulin secretion. In Aim 2A small interfering RNAs will be used to specifically lower levels of certain enzymes that use mitochondrial products. Resulting decreases in insulin release will be compared with alterations in metabolic pathways. In Aim 2B limited focused studies of beta ceil cataplerosis in type 2 diabetes will be performed.