A NOVEL TRANSGENIC MOUSE MODEL FOR DIABETES

描述（由申请人提供）： 该提案旨在建立一种新的转基因小鼠系，称为D2 D，可以作为糖尿病和肥胖症研究的模型。我们的实验室一直在研究葡萄糖调节蛋白GRP 78的转录调控，GRP 78是位于内质网（ER）的主要分子伴侣。为了了解生理应激如何在体内激活Grp 78启动子，我们创建了一系列转基因小鼠品系。这些品系之一，D2 D，含有Grp 78启动子的遗传修饰版本，其驱动编码β-半乳糖苷酶的细菌lacZ基因的表达。在该细胞系中，lacZ转基因活性在所有胰腺β细胞中强烈表达，并且在肝脏和大脑（包括控制葡萄糖感知的下丘脑）中也检测到一些表达。令我们惊讶的是，我们发现D2 D创始人小鼠随着年龄的增长变得越来越肥胖。对创始人及其F1和F2后代的进一步分析表明，D2 D系表现出II型糖尿病和肥胖症年龄依赖性发作的特性。D2 D胰腺切片的检查显示正常范围的β细胞质量、增殖和凋亡。总之，我们的初步结果表明，D2 D可以为II型糖尿病和肥胖提供一种新的模型，并为研究可能与肝脏和大脑问题有关的β细胞缺陷提供一种新的实验系统。在具体目标1中，我们建议对D2 D小鼠和表现出相似但不同的lacZ表达谱的其他两个独立衍生系进行葡萄糖代谢和表型测试的综合分析。在具体目标2中，我们将确定可以解释D2 D中观察到的糖尿病表型的各种机制。该试点项目有可能通过D2 D的整合位点分析来识别对葡萄糖稳态至关重要的新基因，并且它将为未来的研究提供基础，以破译D2 D模型对糖尿病和肥胖症治疗的详细机制和临床前应用。

DESCRIPTION (provided by applicant): This proposal aims to establish a novel transgenic mouse line, referred to as D2D that can serve as a model for the study of diabetes and obesity. Our laboratory has been studying the transcriptional regulation of a glucose regulated protein GRP78 that is a major molecular chaperone localized in the endoplasmic reticulum (ER). To understand how physiological stress activates the Grp78 promoter in vivo, we have created a series of transgenic mouse lines. One of these lines, D2D, contains a genetically modified version of the Grp78 promoter driving the expression of the bacterial lacZ gene encoding for beta-galactosidase. In this line, the lacZ transgene activity is strongly expressed in all pancreatic beta-cells, and some expression is also detected in the liver and brain including the hypothalamus controlling glucose sensing. To our surprise, we discovered that the D2D founder mouse became increasingly obese with age. Further analysis of the founder and its F1 and F2 offspring reveals that the D2D line exhibits properties of type II diabetes and age dependent onset of obesity. Examination of the D2D pancreatic sections showed normal range of beta-cell mass, proliferation and apoptosis. Taken together, our preliminary results suggest that D2D could offer a novel model for type II diabetes and obesity, and provide a new experimental system for the study of beta-cell defect with possible connection to liver and brain problems. In Specific Aim 1, we propose to perform comprehensive analyses of glucose metabolism and phenotypic tests for the D2D mice and two other independently derived lines that exhibit similar but distinct lacZ expression profile. In Specific Aim 2, we will determine the various mechanism(s) that could account for the diabetic phenotype observed in D2D. This pilot project has the potential to identify a new gene critical for glucose homeostasis through integration site analysis of D2D and it will provide the foundation for future studies to decipher the detail mechanism and preclinical applications of the D2D model towards therapy of diabetes and obesity.