Regulation of hepatic insulin sensitivity by CREB

描述(申请人提供)：这项研究的目的是研究转录因子CREB如何调节肝脏胰岛素敏感性。在禁食期间，CREB诱导肝脏中的糖异生基因，而这些基因在餐后胰岛素的反应中被抑制。拟议的研究将检验这一假设，即在禁食期间，CREB通过激活包括胰岛素受体IRS-2在内的胰岛素信号通路中的基因表达，为肝脏有效地停止糖异生做准备。具体地说，我将研究依赖CREB转录的胰岛素途径基因的分子机制，以及这个调控环如何调节葡萄糖稳态。我将评估CREB、其共激活因子TORC2和FOXO转录因子通过RNAi介导的敲除在原代肝细胞中转录这些基因的需求。我还将在体内通过腺病毒感染急性敲除CREB、TORC2和FOXO来研究这一途径对空腹肝脏胰岛素敏感性的影响，然后测量空腹血糖水平、胰岛素耐量和肝脏葡萄糖输出。这项研究将有助于理解在禁食和饮食状态下调节葡萄糖输出和储存之间的平衡的机制。

DESCRIPTION (provided by applicant): The objective of this study is to examine how the transcription factor CREB modulates hepatic insulin sensitivity. During fasting, CREB induces gluconeogenic genes in liver, which are repressed in response to insulin after a meal. The proposed studies will test the hypothesis that during fasting CREB primes the liver for efficient cessation of gluconeogenesis by activating expression of genes in the insulin signaling pathway, including the insulin receptor IRS-2. Specifically, I will investigate the molecular mechanisms of CREB- dependent transcription of insulin pathway genes and how this regulatory loop modulates glucose homeostasis. I will assess the requirements of CREB, its co-activator TORC2, and Foxo transcription factors for transcription of these genes by RNAi-mediated knockdown in primary hepatocytes. I will also examine the effects of this pathway on fasting hepatic insulin sensitivity by acute knockdown of CREB, TORC2 and Foxo by adenovirus infection in vivo followed by measurements of fasting blood glucose levels, insulin tolerance, and hepatic glucose output. This study will contribute to an understanding of the mechanisms regulating the balance between glucose output and storage in fasted versus fed states.