GLUCOKINASE GENE EXPRESSION IN THE PANCREATIC BETA CELL

描述：葡萄糖激酶(GK)是一种高千米的己糖激酶，是一种关键的成分。 胰岛β细胞的葡萄糖感受器和突变 在人类的葡萄糖激酶基因中都与发育成熟有关 青年发作性糖尿病(MODY)，NIDDM的一种早期发病形式。而当 GK基因已被证实是为数不多的几种真正的糖尿病之一 基因，目前还不清楚该基因的突变是如何导致 高血糖症。最近的数据表明，目前的观念是 GK缺陷型NIDDM的高血糖主要是由于葡萄糖引起的 通过β细胞检测缺陷过于简单化了。首先，他们有 在胰腺外神经和神经内分泌细胞中发现了GK， 像胰岛β细胞一样，可能也能感觉到葡萄糖的流动 集中精神。第二，GK核酶转基因小鼠减少了 β细胞中的GK含量受到的影响没有那么严重 已经被预测到了。因此，有必要进行更多的研究，以 更多地了解GK的细胞特异性表达和功能 胰外神经和神经内分泌细胞与胰腺癌的发病机制 GK缺陷型NIDDM。提出了四个相辅相成的具体目标： 具体目标1.培育和鉴定含有以下成分的转基因小鼠 复制83 kb的小鼠葡萄糖激酶基因片段，并检测 转基因拯救致死胚胎表型的能力 观察葡萄糖激酶基因的全部敲除情况。特定目标 2.在转基因小鼠中使用靶向致癌策略来识别 并描述了胰腺外神经内分泌细胞表达 胰岛葡萄糖激酶亚型。具体目标3.确定和描述 负作用顺式调控元件及其结合蛋白(S)， 这抑制了上游葡萄糖激酶启动子的表达。特定的 目的4.建立模型系统，其中葡萄糖激酶可以有条件地 从不同类型的鼠标细胞中移除，最初强调 被放置在清除胰岛β细胞中的葡萄糖激酶上。

DESCRIPTION: Glucokinase (GK), a high Km hexokinase, is a key component of the glucose sensing apparatus of pancreatic beta cells and mutations in the human glucokinase gene are linked to the development of Maturity Onset Diabetes of Youth (MODY), an early onset form of NIDDM. While the GK gene has been established as one of only a few authentic diabetes genes, it is not understood how mutations in this gene actually cause hyperglycemia. Recent data suggests that the current notion that hyperglycemia in GK-deficient NIDDM is due primarily to a glucose sensing defect by the beta cell is overly simplistic. First, they have identified GK in extrapancreatic neural and neuroendocrine cells that, like pancreatic beta cells, may also be able to sense fluxes in glucose concentration. Second, GK ribozyme transgenic mice that have reduced amounts of GK in the beta cells are less severely affected than might have been predicted. Additional studies are necessary, therefore, to understand more about the cell-specific expression and function of GK in extrapancreatic neural and neuroendocrine cells and the pathogenesis of GK- deficient NIDDM. Four complementary Specific Aims are proposed: Specific Aim 1. Produce and characterize transgenic mice that contain copies of an 83 kb fragment of the mouse glucokinase gene and test the ability of the transgene to rescue the lethal embryonic phenotype observed with the total knock-out of the glucokinase gene. Specific Aim 2. Use a strategy of targeted oncogenesis in transgenic mice to identify and characterize extrapancreatic neuroendocrine cells that express the islet glucokinase isoform. Specific Aim 3. Identify and characterize negatively-acting cis-regulatory elements, and their binding protein(s), that repress expression of the upstream glucokinase promoter. Specific Aim 4. Establish a model system in which glucokinase can be conditionally removed from different cell types of the mouse with initial emphasis being placed on eliminating glucokinase in pancreatic beta cells.