The Distinct Role of CBP and p300 in Regulating Hepatic Glucose Production

描述（由申请人提供）：糖尿病在全球范围内变得越来越普遍，1980年至2005年期间，美国新诊断的成人人数几乎增加了两倍。2型糖尿病中的空腹高血糖症是由胰岛素抵抗和胰高血糖素水平升高引起的，这导致不可抑制的肝脏葡萄糖产生。我们已经证明，抗糖尿病药物二甲双胍和胰岛素都通过PKC β/β在丝氨酸436处磷酸化转录辅激活因子CBP，导致肝葡萄糖产生的抑制。一个相关的辅激活因子p300，缺乏这个磷酸化位点，也是调节葡萄糖产生的重要介质。我们在这个K99/R 00奖项中提出了3个目标，以进一步了解p300/CBP类共激活因子对肝脏肿瘤发生的转录调控。在目的1中，我们将在p300突变小鼠的空腹和进食状态下表征胰岛素信号传导和促胰岛素生成酶基因表达谱，其中PKC？/？磷酸化位点已被重建。在目标2中，我们将确定蛋白磷酸酶介导的胰高血糖素去磷酸化的CBP在Ser 436。在目标3中，我们将确定CREB-p300/CBP-TORC 2复合物中的每种共激活剂在增强肝脏新生中的作用以及CBP和p300的相互乙酰化在介导肝脏葡萄糖产生中的重要性。目标1中的研究将在辅导K99阶段完成，而目标2和3将在独立R 00阶段完成。本提案中的机制研究探索了胰岛素和胰高血糖素在控制肝脏葡萄糖产生中的作用，对于开发有效的糖尿病治疗新模式至关重要。 公共卫生相关性：本研究拟探讨p300在肝脏葡萄糖生成中的作用，确定CBP的胰高血糖素去磷酸化过程，以及CBP和p300的乙酰化在调节肝脏葡萄糖生成中的作用。我们希望为2型糖尿病患者中发现的高血糖的发展提供机制上的理解。

DESCRIPTION (provided by applicant): Diabetes mellitus is becoming more prevalent worldwide, with the number of newly diagnosed adults nearly tripling between 1980 and 2005 in the US. Fasting hyperglycemia in type 2 diabetes mellitus is caused by insulin resistance and elevated glucagon levels, which result in non-suppressible hepatic glucose production. We have shown that both the anti-diabetic agent metformin and insulin phosphorylate the transcriptional co-activator CBP at serine 436 via PKC?/?, leading to the suppression of hepatic glucose production. A related co-activator, p300, lacking this phosphorylation site, is also am important mediator in regulation glucose production. We propose 3 aims in this K99/R00 award to further understand transcriptional regulation of hepatic gluconeogenesis by the p300/CBP class of co-activators. In Aim 1, we will characterize the insulin signaling and gluconeogenic enzyme gene expression profile in the fasted and fed states in p300 mutant mice where the PKC?/??phosphorylation site has been reconstituted. In Aim 2, we will identify the protein phosphatase mediating glucagon dephosphorylation of CBP at Ser436. In Aim 3, we will define the role of each co-activator in the CREB-p300/CBP-TORC2 complex in augmenting gluconeogenesis and the importance of inter-acetylation of CBP and p300 in mediating hepatic glucose production. The studies in Aim 1 will be finished in mentored K99 phase, while Aims 2 and 3 will be finished in the independent R00 phase. The mechanistic studies in this proposal, which explore the actions of insulin and glucagon in controlling hepatic glucose production, will be critical for the development of effective new modalities in the treatment of diabetes mellitus. PUBLIC HEALTH RELEVANCE: in this proposal, we will attempt to define the roles of p300 in gluconeogenesis; identify the protein phosphatase mediated glucagon dephosphorylation of CBP; determine the acetylation of CBP and p300 in regulating glucose production in the liver. We hope to provide mechanistic understanding for the development of hyperglycemia found in patients with type 2 diabetes mellitus.