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

描述(申请人提供)：糖尿病正在世界范围内变得越来越普遍，美国新诊断的成年人数量在1980年至2005年间几乎增加了两倍。2型糖尿病的空腹高血糖是由胰岛素抵抗和高血糖素水平升高引起的，这会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？/？使转录辅助激活因子CBP在丝氨酸436处磷酸化，从而抑制肝脏葡萄糖的产生。一个相关的共激活因子p300缺乏这个磷酸化位点，也是调节葡萄糖产生的重要介质。我们在这项K99/R00奖中提出了3个目标，以进一步了解p300/CBP类共激活剂对肝脏糖异生的转录调控。在目标1中，我们将表征p300突变小鼠在禁食和进食状态下的胰岛素信号和糖异生酶基因表达谱，其中p300突变小鼠的PKC？/？磷酸化位点已被重组。在目标2中，我们将鉴定介导CBP在Ser436处的胰高血糖素去磷酸化的蛋白磷酸酶。在目标3中，我们将确定CREB-p300/CBP-TORC2复合体中每个辅助激活子在促进糖异生中的作用，以及CBP和p300之间的乙酰化在调节肝脏葡萄糖产生中的重要性。目标1的研究将在指导K99阶段完成，目标2和目标3将在独立的R00阶段完成。这项建议中的机制研究，探索胰岛素和胰升糖素在控制肝脏葡萄糖产生中的作用，将对开发有效的糖尿病治疗新方法至关重要。 公共卫生相关性：在这项提案中，我们将尝试确定p300在糖异生中的作用；确定蛋白磷酸酶介导的CBP的胰升糖素去磷酸化；确定CBP和p300的乙酰化在调节肝脏葡萄糖产生中的作用。我们希望为2型糖尿病患者高血糖的发生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.