REGULATION OF BETA CELL GENES BY GLUCOSE AND INCRETINS

葡萄糖和肠促胰素对 β 细胞基因的调节

• 批准号: 8171328
• 负责人: MARC R MONTMINY
• 金额: $ 0.24万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8171328
• 关键词: 14-3-3 Proteins; Address; Beta Cell; CREB1 gene; Calcineurin inhibitor; Calcium; Calcium Signaling; Cell Death; Cell Nucleus; Cell Survival; Complex; Complication; Computer Retrieval of Information on Scientific Projects Database; Cues; Cyclic AMP; Cytoplasm; Diabetes Mellitus; EP300 gene; FK506; Family; Funding; Gene Expression; Genes; Genetic Programming; Genetic Transcription; Glucose; Grant; Immunosuppression; Institution; Insulin; Islet Cell; Islets of Langerhans; Knock-out; Mediating; Modification; Mus; Mutation; Nuclear; Pathway interactions; Patients; Phosphorylation; Process; Protein Kinase; Proteins; RNA Interference; Regulation; Relative (related person); Research; Research Personnel; Resources; Role; Source; Transducers; Transplantation; United States National Institutes of Health; calcineurin phosphatase; feeding; incretin hormone; inhibitor/antagonist; islet; mutant; novel; pancreatic islet function; paralogous gene; polypeptide; promoter; response

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Glucose and incretin hormones trigger the expression of genetic programs that enhance islet cell survival and promote insulin release during feeding. The activation of cAMP and calcium pathways in response to these cues promotes islet gene expression and beta cell survival in part by stimulating the phosphorylation of CREB at Ser133, a modification that stimulates recruitment of the coactivator paralogs CBP and P300 to the promoter. Mice with knockin mutations in CBP and P300 that disrupt their association with CREB show only modest changes in cAMP dependent transcription, however, suggesting the potential involvement of additional CREB coactivators in this process. The current proposal focuses on the role of a novel family of CREB coactivators, designated TORCs for Transducers of Regulated CREB activity, in promoting islet gene expression. Preliminary studies reveal that islet TORC proteins are retained in the cytoplasm under basal conditions, migrating to the nucleus in response to cAMP and calcium signals where they potentiate CREB target gene expression. Specific Aim I addresses the mechanism by which TORC activity is suppressed under basal conditions, focusing on the role of a TORC associated protein kinase in promoting TORC phosphorylation and cytoplasmic retention via an interaction with 14-3-3 proteins. Aim II addresses the mechanism of TORC activation in response to cAMP and calcium, with particular emphasis on the role of the ser/thr phosphatase calcineurin in dephosphorylating and promoting nuclear entry of TORC. Aim III examines the relative importance of CREB:TORC and CREB:CBP complexes for pancreatic islet gene expression by using mutant CREB polypeptides that are defective in either CBP or TORC interaction. Regulatory contributions of TORC and CBP/P300 towards CREB target gene expression islet cells will also be explored by disrupting the expression of each coactivator through RNAi mediated knockdown. Finally, the role of TORCs in pancreatic islet function will be determined by generating mice with a conditional knockout of the TORC genes. Post-transplant diabetes is a frequent complication in patients receiving calcineurin inhibitors such as FK506 for immunosuppression. The proposed studies will reveal whether these inhibitors promote islet cell death, in part by interfering with expression of islet survival genes through the CREB:TORC pathway.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 葡萄糖和肠促胰岛素激素触发遗传程序的表达，增强胰岛细胞存活并促进进食期间胰岛素的释放。响应于这些信号的cAMP和钙途径的激活部分地通过刺激CREB在Ser 133处的磷酸化来促进胰岛基因表达和β细胞存活，这是一种刺激共激活因子旁系同源物CBP和P300募集到启动子的修饰。CBP和P300敲入突变破坏其与CREB的关联的小鼠仅显示cAMP依赖性转录的适度变化，然而，这表明在该过程中可能涉及额外的CREB共激活因子。目前的建议集中在一个新的CREB共激活因子家族的作用，指定为调节CREB活性的换能器的TORCs，在促进胰岛基因表达。初步研究表明，胰岛TORC蛋白在基础条件下保留在细胞质中，响应cAMP和钙信号迁移到细胞核，在那里它们增强CREB靶基因表达。具体目标I解决了基础条件下TORC活性被抑制的机制，重点关注TORC相关蛋白激酶通过与14-3-3蛋白的相互作用在促进TORC磷酸化和细胞质保留中的作用。目的II解决响应cAMP和钙的TORC激活的机制，特别强调Ser/Thr磷酸酶钙调神经磷酸酶在TORC去磷酸化和促进核进入的作用。目的III通过使用CBP或TORC相互作用缺陷的突变CREB多肽来检查CREB：TORC和CREB：CBP复合物对胰岛基因表达的相对重要性。TORC和CBP/P300对CREB靶基因表达胰岛细胞的调节作用也将通过RNAi介导的敲低破坏每种辅激活因子的表达来探索。最后，将通过产生具有条件性敲除TORC基因的小鼠来确定TORC在胰岛功能中的作用。移植后糖尿病是接受钙调磷酸酶抑制剂（如FK 506）用于免疫抑制的患者的常见并发症。拟议的研究将揭示这些抑制剂是否会促进胰岛细胞死亡，部分原因是通过CREB：TORC途径干扰胰岛存活基因的表达。