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 E1a刺激基因抑制因子1(CREG1)是一种参与细胞膜转运的小糖蛋白。 胰岛素提示，内吞和分泌途径可能参与了T2 DM的发病机制 全身Creg1基因敲除小鼠的抵抗力、糖耐量异常、高血糖和低胰岛素血症。 利用培养的肝细胞和肝脏特异性Creg1基因敲除小鼠的功能获得和功能丧失研究 证明CREG1自主调节细胞胰岛素信号、胰岛素敏感性和 质膜上的胰岛素受体。在胰腺？-细胞特异性Creg1基因敲除的胰岛中，增加 胰岛素原和胰岛素水平降低会导致胰岛素分泌受损。此外，CREG1的表达为 在营养上受到调节，并被高脂肪饮食的摄入量逐渐下调。此项目将测试(%1) CREG1的缺失是否会抑制胰岛素受体的循环，从而损害胰岛素信号和胰岛素 作用，(2)CREG1下调在多大程度上促进代谢性疾病中的胰岛素抵抗，以及(3) Creg1消融是否阻碍胰岛素颗粒转运和增强胰岛素降解。第一个目标是， 我们将描述CREG1在调节胰岛素受体转运中的作用及其对肝脏的贡献 胰岛素作用与细胞内胰岛素信号传导。我们将通过腺病毒载体恢复高脂饮食小鼠CREG1的表达。 相关病毒介导的CREG1基因传递，并测试这是否改善了胰岛素敏感性和胰岛素信号。 在第二个目标中，我们将阐明CREG1的缺失是如何导致？细胞胰岛素含量降低的，重点是 胰岛素原加工和胰岛素降解。脉冲追逐标记和活细胞成像，电子显微镜， 生化分析和复杂的生理研究方案将在建议中使用 学习。我们的长期目标是阐明CREG1是如何调节肝脏胰岛素作用和细胞胰岛素的。 分泌，并靶向CREG1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.