Does insulin or glucose regulate alpha-cell function?

胰岛素或葡萄糖调节α细胞功能吗？

• 批准号: 6908621
• 负责人: BARTON WICKSTEED
• 金额: $ 17.5万
• 依托单位: PACIFIC NORTHWEST RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6908621
• 关键词: biological signal transduction; blood glucose; cell aggregation; flow cytometry; gene expression; glucagon; green fluorescent proteins; hormone biosynthesis; hormone regulation /control mechanism; hypoglycemia; insulin; insulin receptor; laboratory rat; messenger RNA; nutrient interaction; nutrition related tag; pancreatic islet function; proinsulin; receptor expression; tissue /cell culture; transfection /expression vector

DESCRIPTION (provided by applicant): Blood glucose remains within a narrow range, primarily due to insulin and glucagon, which are secreted from the beta and alpha cells of the islets of Langerhans, respectively. Although insulin secretion has been well studied the signals that regulate glucagon secretion are still hotly debated. Hypoglycemia is a significant cause of death amongst Type I diabetics and the major limitation upon insulin treatment of hyperglycemia. Thus, it is crucial to understand how alpha cells sense and respond to circulating glucose levels. It is unclear whether glucose is detected directly or whether the alpha cell is under the control of neighboring beta cells, most likely through insulin secretion. This study will develop 2 methods by which we can separate primary rat alpha cells from the effects of neighboring beta cells. The first approach is to obtain pure alpha cell populations using green fluorescent protein (GFP) expression restricted to the alpha cells to tag these cells for purification by fluorescence activated cell sorting (FACS). Techniques will then be developed to optimize the conditions for culturing these purified alpha cells. The use of cell aggregation and cell monolayers will be examined to determine which method gives the tighter regulation of glucagon secretion. The other method is to down-regulate insulin receptor expression in the alpha cells. The aim of the second aspect of this study is to identify steps of proglucagon gene expression (RNA levels, RNA stability and proglucagon translation) that are regulated in response to glucose and/or insulin. The identification of such steps would provide novel read-outs by which to study alpha cell responses to nutrients. Furthermore, the regulation of gene expression at mRNA stability and translation is almost always via RNA-protein interactions, the identification of which would provide valuable tools in the dissection of nutrient effects upon the alpha cell. The research described in this proposal will provide new techniques and new read-outs by which the study of the alpha cell responses to its nutrient environment can be studied.

描述（由申请人提供）：血糖保持在一个狭窄的范围内，主要是由于胰岛素和胰高血糖素，它们分别由朗格汉斯岛的β和α细胞分泌。尽管胰岛素分泌已得到充分研究，但调节胰高血糖素分泌的信号仍存在激烈争论。低血糖是I型糖尿病患者死亡的重要原因，也是胰岛素治疗高血糖的主要限制。因此，了解α细胞如何感知和响应循环葡萄糖水平至关重要。目前尚不清楚葡萄糖是直接检测到还是α细胞是否受到邻近β细胞的控制（很可能是通过胰岛素分泌）。这项研究将开发两种方法，通过它们我们可以将原代大鼠α细胞与邻近β细胞的影响分开。第一种方法是使用仅限于 α 细胞的绿色荧光蛋白 (GFP) 表达来标记这些细胞，以便通过荧光激活细胞分选 (FACS) 进行纯化，从而获得纯的 α 细胞群。然后将开发技术来优化培养这些纯化的α细胞的条件。将检查细胞聚集和细胞单层的使用，以确定哪种方法可以更严格地调节胰高血糖素分泌。另一种方法是下调α细胞中胰岛素受体的表达。本研究第二个方面的目的是确定响应葡萄糖和/或胰岛素而调节的胰高血糖素原基因表达步骤（RNA 水平、RNA 稳定性和胰高血糖素原翻译）。这些步骤的识别将为研究α细胞对营养物质的反应提供新的读数。此外，基因表达对 mRNA 稳定性和翻译的调节几乎总是通过 RNA-蛋白质相互作用进行，其鉴定将为剖析营养对 α 细胞的影响提供有价值的工具。该提案中描述的研究将提供新技术和新读数，通过这些技术和新读数可以研究α细胞对其营养环境的反应。