IDENTIFICATION/CHARACTERIZATION OF RIPE3B1

位于-340至-91碱基对（bp）之间的5 '侧翼区序列介导胰岛素基因的胰腺β细胞特异性和葡萄糖调节的转录。C2（-317/-311 bp）、A3（-301至-196 bp）、C1（-118和-107 bp）和E1（-100至-91 bp）元件在控制中是必需的。胰岛素C2-、A3-和E1-补体刺激的transcription的激活剂分别是PAX 6、PDX-1和BETA 2。引人注目的是，进行的基因去除实验也清楚地建立了这些胰岛富集转录因子中的每一种在胰腺发育期间在小鼠中的基本功能。此外，Pdx-1和BETA2基因中的杂合突变导致2型糖尿病中的β细胞功能障碍。这些发现说明了如何识别和表征胰岛富集产品（如胰岛素）的关键转录调节因子，对于我们理解影响β细胞的疾病过程至关重要。然而，很少有人知道的蛋白质（S）参与C1元件的刺激。在凝胶迁移率变动分析中，与这些元件形成的RIPE 3b 1因子DNA复合物在β细胞提取物中被唯一检测到，并且在葡萄糖处理的β细胞中与胰岛素基因转录的变化平行地被选择性调节。这些结果强烈暗示RIPE 3b 1复合物含有在胰岛素转录的生理调节中重要的DNA结合蛋白。包含C1元件的序列与任何已知的转录因子结合的序列无关，这强烈表明RIPE 3b 1将是一种新的DNA结合转录因子。我们的第一个目标是分离和表征RIPE 3b 1蛋白的激活特性。我们的第二个目标将是研究胰腺发育和胰岛β细胞功能如何在缺乏RIPE 3b 1的小鼠中受到影响。这些实验将确定RIPE 3b 1蛋白在细胞特异性和葡萄糖调节的胰岛素基因转录调节中以及在胰腺发生期间的作用。

The 5'-flanking region sequences located between-340 to -91 base pairs (bp) mediate pancreatic beta cell-specific and glucose-regulated transcription of the insulin gene. The C2 (-317/-311 bp)), A3 (-301 to - 196 bp), C1 (-118 and -107 bp), and E1 (-100 to -91 bp) elements are essential in control. The activators of insulin C2-, A3-, and E1- complement stimulated transcriptions are PAX6, PDX-1 and BETA2, respectively. Strikingly, gene ablation experiments performed have also clearly established an essential function in mice for each of these islet- enriched transcription factor during pancreatic development. In addition, heterozygous mutations in the Pdx-1 and BETA2 genes contribute to beta cell dysfunction in type 2 diabetes. These findings illustrate how the identification and characterization of the critical transcription regulators of islet-enriched products, like insulin, are essential for our understanding of the disease process affecting the beta cell. However, little is known about the protein(s) involved in C1 element stimulation. The RIPE3b1 factor DNA complex formed with these element in gel mobility shift assays is uniquely detected in beta cells extracts, and is selectively regulated in parallel with changes in insulin gene transcription in glucose- treated beta cells. These results strongly imply that the RIPE3b1 complex contains a DNA-binding protein(s) important in the physiological regulation of insulin transcription. The sequences comprising the C1 element are unrelated to those bound by any known transcription factor, strongly suggesting that RIPE3b1 will be a novel DNA-binding transcription. Our first objective will be to isolate and characterize the activation properties of the RIPE3b1 protein(s). Our second objective will be to examine how pancreatic development and islet beta cell function is affected in mice lacking RIPE3b1. These experiments will determine the role of the RIPE3b1 protein(s) in both cell-specific and glucose- modulated regulation of insulin gene transcription and during pancreaogenesis.