GUT PEPTIDE EXPRESSION IN THE ENDOCRINE PANCREAS

胰岛的内分泌细胞由胰腺发育而来。 多能内皮细胞向内分泌干细胞承诺的萌芽 (内胚层细胞)，在终末分化为 成熟的胰岛细胞。除了胰岛素和胰升糖素外，正在发展中的胰岛 细胞还瞬时表达在成体胰岛中不活跃的基因 允许胎儿内胚层细胞生长。其中一个是瞬间表达的 胃泌素基因是一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依赖于胰岛 与胰岛素增强剂DNA类似的特定顺式作用DNA元件 转基因研究的目的是显示胃泌素启动子在 由同一细胞特异性转录因子(反式激活因子)诱导的胰岛细胞 这会激活胰岛素基因。这将通过分析来证实 DNA酶足迹和甲基化在体外DNA/蛋白质相互作用中的应用 干扰研究。含有胃泌素基因缺失的转基因 胰岛素增强子域将被插入到小鼠的生殖系中 如果这一缺失取消了胃泌素转基因在胰腺的表达 在体内胎儿发育过程中。 出生后胰岛细胞的终末分化导致两者的丢失 胃泌素基因表达的增殖能力和消退。小岛 细胞表达一种特定的转录抑制物，它与一种 如果胃泌素启动子与胰岛素相邻，则DNA元件为阴性 增强子样正性元件。胃泌素基因编码区的克隆 抑制物将通过筛选胰岛c DNA文库来启动 胃泌素阴性元件作为DNA探针。蜂窝信号 将对调节胃泌素抑制物活性进行分析以阐明其潜力 胰岛发育中胃泌素基因表达的调控机制。 含胃泌素基因缺失的转基因表达分析 否定成分的目的是证明该否定成分在 胰腺胃泌素基因表达的出生后消退 有助于胰岛细胞在出生后停止生长。这些研究是关于 胃泌素启动子的调控旨在分析 在胰腺发育过程中调节胰岛生长。了解这些 这些事件可能导致改善I型胰岛细胞再生的方法 糖尿病。

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.