DYNAMICS OF PANCREATIC ISLET FUNCTION

胰岛功能的动态变化

• 批准号: 6138071
• 负责人: David W Piston
• 金额: $ 22.05万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6138071
• 关键词: Adenoviridae; NAD(H) phosphate; adenosine diphosphate; adenosine triphosphate; biological signal transduction; confocal scanning microscopy; enzyme activity; enzyme mechanism; fluorescence microscopy; gap junctions; gene expression; gene targeting; genetically modified animals; glucokinase; glucose metabolism; immunofluorescence technique; insulin; intracellular; laboratory mouse; pancreatic islet function; recombinant virus; secretion; tissue /cell culture

DESCRIPTION (Adapted from applicant's abstract): It has long been established that b-cells within whole islets secrete more insulin than do isolated b-cells. This functional enhancement may arise from gap junctional coupling between cells in the intact islet. Until now, the behavior of b-cells within islets has been largely inferred from in vitro studies of dispersed cells and biochemical analysis of whole islets. Dr. Piston has begun to study the function of individual b- cells within intact islets by optimizing recent advances in quantitative optical imaging for this purpose. This has led to novel experiments which show marked differences between isolated b-cells and whole islets in NAD(P)H autofluoresence (an endogenous reporter of intracellular metabolism) and glucokinase (GK) expression. These results demonstrate a new level of biological complexity that can be investigated only by detailed studies of intact islets. Dr. Piston hypothesizes that insulin secretion is directly coupled to glucose metabolism, and that while both responses are rate-limited by GK activity under normal physiological conditions, this rate-limiting role may be lost by only a slightly over-expression of GK. The applicant also hypothesizes that gap junctional coupling between b- cells in the islet accounts for increased insulin secretion from b- cells in the intact islet over isolated b- cells. The validity and limits of these hypotheses will be addressed through three specific aims: 1) To determine the temporal relationship between the magnitude of glucose-stimulated NAD(P)H response and amount of insulin secretion; 2) To determine the range of expression levels over which GK maintains its rate-limiting role in islet metabolism and secretion; 3) To determine the ability of intercellular coupling to enhance insulin secretion. The proposed experiments take advantage of the applicant's demonstrated expertise in two-photon excitation and confocal microscopic techniques, combined with several available transgenic mouse models. The applicant concludes that these investigations will advance our understanding of the in vivo interplay of biochemical mechanisms known to be involved in glucose-stimulated insulin secretion from pancreatic islets.

描述（改编自申请人的摘要）：长期以来一直是 确定整个胰岛内的B细胞比这样做更大的胰岛素 孤立的B细胞。 这种功能增强可能是由于间隙连接的 完整胰岛中细胞之间的耦合。 到目前为止， 胰岛内的B细胞主要是根据体外研究推断的 整个胰岛的分散细胞和生化分析。 活塞博士有 开始研究完整胰岛中单个B细胞的功能 为此目的优化定量光学成像的最新进展。 这导致了新的实验，这些实验表明 NAD（p）H自动荧光中的孤立的B细胞和整个胰岛（内源性 细胞内代谢）和葡萄糖激酶（GK）表达的记者。 这些结果表明了一种新的生物学复杂性，可以是 仅通过完整胰岛的详细研究进行调查。 活塞博士 假设胰岛素分泌直接耦合到葡萄糖 新陈代谢，尽管这两个响应都是由GK活性限制的 在正常的生理条件下，这种限速作用可能会丢失 GK仅略有表达。 申请人还假设 胰岛中B细胞之间的差距连接耦合的解释 完整胰岛中B细胞分泌的胰岛素分泌增加了 B-细胞。 这些假设的有效性和限制将被解决 通过三个特定目标：1）确定时间关系 在葡萄糖刺激的NAD（P）H响应的大小与数量之间 胰岛素分泌； 2）确定表达水平的范围 GK在胰岛代谢和分泌中保持其限制性作用； 3）到 确定细胞间耦合增强胰岛素的能力 分泌。 提议的实验利用了申请人的优势 在双光子激发和共聚焦微观方面具有专业知识 技术与几种可用的转基因小鼠模型结合使用。 这 申请人得出的结论是，这些调查将提高我们的理解 生化机制的体内体内相互作用 胰岛中葡萄糖刺激的胰岛素分泌。