Role of CREG1 in metabolic homeostasis

项目摘要 2型糖尿病（T2 DM）是由胰岛素抵抗和胰岛素分泌减少引起的。蜂窝 E1 A刺激基因1（CREG 1）的阻遏物，一种参与细胞膜运输的小糖蛋白， 内吞和分泌途径，可能参与T2 DM的发病机制，如胰岛素 抵抗、葡萄糖耐受不良、升高的胰岛素抵抗和低胰岛素血症。 使用培养的肝细胞和肝脏特异性Creg 1敲除小鼠进行的功能获得和丧失研究 表明CREG 1自主调节细胞胰岛素信号传导、胰岛素敏感性和表达。 胰岛素受体的表达。在胰腺？-细胞特异性Creg 1敲除胰岛，增加 胰岛素原和胰岛素水平降低导致胰岛素分泌受损。此外，CREG 1表达是 营养调节，并通过高脂肪饮食消耗逐渐下调。本项目将测试（1） CREG 1的缺失是否抑制胰岛素受体再循环并因此损害胰岛素信号传导和胰岛素 作用，（2）CREG 1下调在多大程度上有助于代谢疾病中的胰岛素抵抗，以及（3） Creg 1消融是否阻碍胰岛素颗粒运输并增强胰岛素降解。在第一个目标中， 我们将描述CREG 1在调节胰岛素受体运输中的作用及其对肝细胞凋亡的影响。 胰岛素作用和细胞胰岛素信号传导。我们将在高脂饮食喂养的小鼠中通过腺病毒介导的方法恢复CREG 1的表达。 相关病毒介导的CREG 1基因传递，并测试这是否改善胰岛素敏感性和胰岛素信号传导。 在第二个目标中，我们将阐明CREG 1的丢失如何导致？细胞胰岛素含量，重点是 胰岛素原加工和胰岛素降解。脉冲追踪标记和活细胞成像，电子显微镜， 和生化分析结合复杂的生理研究协议将用于拟议的 问题研究我们的长期目标是阐明CREG 1如何调节肝脏胰岛素的作用，细胞胰岛素 分泌，并靶向CREG 1以治疗T2 DM。

Project Summary Type 2 diabetes mellitus (T2DM) is caused by insulin resistance and reduced insulin secretion. Cellular repressor of E1A-stimulated genes 1 (CREG1), a small glycoprotein involved in membrane trafficking in the endocytic and secretory pathways, may be involved in the pathogenesis of T2DM, as suggested by the insulin resistance, glucose intolerance, elevated glycemia and hypoinsulinemia in whole-body Creg1 knockout mice. Gain- and loss-of-function studies using cultured hepatocytes and liver-specific Creg1 knockout mice demonstrate that CREG1 autonomously regulates cellular insulin signaling, insulin sensitivity, and the expression of insulin receptor on the plasma membrane. In pancreatic ?-cell-specific Creg1 knockout islets, increased proinsulin and diminished insulin levels lead to impaired insulin secretion. Furthermore, CREG1 expression is nutritionally regulated and is progressively downregulated by high-fat diet consumption. This project will test (1) whether loss of CREG1 inhibits insulin receptor recycling and consequently impairs insulin signaling and insulin action, (2) to what degree CREG1 downregulation contributes to insulin resistance in metabolic disease, and (3) whether Creg1 ablation impedes insulin granule trafficking and enhances insulin degradation. In the first Aim, we will delineate the role of CREG1 in the regulation of insulin receptor trafficking and its contribution to hepatic insulin action and cellular insulin signaling. We will restore CREG1 expression in high fat diet fed mice via adeno- associated virus-mediated CREG1 gene delivery and test if this improves insulin sensitivity and insulin signaling. In the second Aim, we will elucidate how loss of CREG1 leads to reduced ?-cell insulin content with a focus on proinsulin processing and insulin degradation. Pulse-chase labeling and live cell imaging, electron microscopy, and biochemical analysis combined with complex physiological study protocols will be used in the proposed studies. Our long-term goals are to elucidate how CREG1 regulates hepatic insulin action and ?-cell insulin secretion, and to target CREG1 to treat T2DM.