GUT PEPTIDE EXPRESSION IN THE ENDOCRINE PANCREAS

内分泌胰腺中肠肽的表达

• 批准号: 3243176
• 负责人: STEPHEN BRAND
• 金额: $ 21.65万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-01-10 至 1994-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3243176
• 关键词: DNA footprinting; affinity chromatography; cell differentiation; diabetes mellitus; gastrins; genetic promoter element; genetically modified animals; growth /development; histogenesis; hormone regulation /control mechanism; laboratory mouse; methylation; nucleic acid probes; pancreatic islets; transcription factor; transfection

The endocrine cells of the pancreatic islets develop from the pancreatic bud by commitment of pluripotent endodermal cells to endocrine stem cells (nesidioblasts) which proliferate before terminally differentiating into mature islet cells. In addition to insulin and glucagon, developing islet cells also transiently express genes not active in adult islets which permit growth of fetal nesidioblasts. One of these transiently expressed genes, gastrin, is an autocrine growth factor for some islet cell lines. Activity of the gastrin promoter in islet cells depends on an islet specific, cis-acting DNA element similar to the insulin enhancer, DNA transfection studies aim to show that the gastrin promoter is activated in islet cells by the same cell specific transcription factor (transactivator) which activates the insulin gene. This will be confirmed by analysing DNA/protein interactions in vitro using DNAase footprinting and methylation interference studies. Gastrin transgenes containing deletions of the insulin enhancer domain will be inserted into the germline of mice to see if this deletion abolishes pancreatic expression of the gastrin transgene during fetal development in vivo. Terminal differentiation of islet cells after birth results in both loss of proliferative capacity and extinction of gastrin gene expression. Islet cells express a specific transcriptional repressor which binds to a negative DNA element if the gastrin promoter adjacent to the insulin enhancer-like positive element. Cloning of the cDNA encoding the gastrin repressor will be initiated by screening an islet cDNA library using the gastrin negative element as a DNA probe. The cellular signals which regulate gastrin repressor activity will be analysed to elucidate potential mechanisms controlling gastrin gene expression in islet development. Analysing the expression of gastrin transgenes containing deletions of the negative element aim to demonstrate that this negative element mediates the postnatal extinction of pancreatic gastrin gene expression which in turn contributes the postnatal cessation of islet cell growth. These studies on the regulation of gastrin promoter aim to analyse the molecular events that regulate islet growth during pancreatic development. Understanding these events may lead to ways of improving islet cell regeneration in type I diabetes.

胰岛的内分泌细胞由胰脏发育而来 通过多能内胚层细胞向内分泌干细胞的承诺而出芽 （nesidioblasts）在最终分化为之前增殖 成熟的胰岛细胞。 除了胰岛素和胰高血糖素外，发育中的胰岛 细胞还瞬时表达在成年胰岛中不活跃的基因 允许胎儿成纤维细胞生长。 其中之一是短暂表达的 胃泌素基因是某些胰岛细胞系的自分泌生长因子。 胰岛细胞中胃泌素启动子的活性取决于胰岛 与胰岛素增强剂 DNA 相似的特定顺式作用 DNA 元件 转染研究旨在表明胃泌素启动子在 胰岛细胞由相同的细胞特异性转录因子（反式激活因子）组成 它激活胰岛素基因。 这将通过分析来证实 使用 DNAase 足迹和甲基化进行体外 DNA/蛋白质相互作用 干扰研究。 含有缺失的胃泌素转基因 胰岛素增强子结构域将被插入小鼠种系中以观察 如果这种删除消除了胃泌素转基因的胰腺表达 胎儿体内发育过程中。 出生后胰岛细胞的终末分化导致 增殖能力和胃泌素基因表达的消退。 胰岛 细胞表达特定的转录抑制因子，该抑制因子与 如果胃泌素启动子与胰岛素相邻，则为阴性 DNA 元件 增强子样阳性元件。 编码胃泌素的 cDNA 的克隆 阻遏蛋白将通过使用以下方法筛选胰岛 cDNA 文库来启动： 胃泌素阴性元件作为 DNA 探针。 细胞信号 将分析调节胃泌素抑制活性以阐明潜力 胰岛发育中胃泌素基因表达的控制机制。 分析含有缺失的胃泌素转基因的表达 消极因素的目的是证明这种消极因素介导了 出生后胰腺胃泌素基因表达消失，进而 有助于出生后胰岛细胞生长的停止。 这些研究关于 胃泌素启动子的调控旨在分析以下分子事件： 在胰腺发育过程中调节胰岛生长。 了解这些 事件可能导致改善 I 型胰岛细胞再生的方法 糖尿病。