A stress inducible Pdx1 transcriptional complex governing beta cell survival

项目摘要 胰腺β细胞的衰竭是所有形式糖尿病进展的基础。β细胞是独一无二的 由于胰岛素生物合成的高需求，对应激诱导的细胞死亡敏感， 分泌和氧化应激导致的充分记录的低抗氧化酶 活动胰腺和十二指肠同源框1（PDX 1）是人类糖尿病基因， 在饮食诱导的胰岛代偿期间β细胞功能和存活所需的因子 胰岛素抵抗我们发现Pdx 1与激活转录因子（ATF）复合， 协调细胞应激反应。我们假设PDX 1、ATF 4和 ATF 5形成应激应答转录调控复合物，其在应激下指导β细胞命运。 应力条件这将在三个具体目标中进行测试：1。描述压力引起的 PDX 1转录复合物，2.确定应激诱导的PDX 1的转录靶点 转录复合物，和3.阐明PDX 1靶点在β细胞存活中的功能作用。 我们将采用最先进的蛋白质组学技术来鉴定压力的组成部分- 诱导的PDX 1转录复合物和任何相关的翻译后修饰。 此外，我们将整合小鼠和人β细胞的ChIPExo和RNASeq谱， 生理学和病理生理学相关的压力，以获得全面的全基因组 利用近碱基对分辨率鉴定该复合物的转录靶点 的ChIP-Exo来解析转录因子结合的结构上不同的模式，从而使 对β细胞中应激反应基因调控的新见解。最后，我们将继续 Pdx 1-Atf 4-Atf 5靶Gpt 2在原代小鼠和人胰岛中的功能作用，以测试 假设β细胞通过燃料过量以类似的方式代谢重编程 在癌细胞转化过程中发生的变化。这些结果将描述新的 调节细胞命运决定的基因靶点对β细胞存活很重要， 糖尿病相关的压力，并扩大人类糖尿病的翻译应用， PDX 1应激反应转录复合物。

Project Summary Failure of pancreatic β cells underlies the progression of all forms of diabetes. β cells are uniquely susceptible to stress induced cell death due to the high demand of insulin biosynthesis and secretion and to oxidative stresses resulting from well-documented low antioxidant enzyme activity. Pancreatic and duodenal homeobox 1 (PDX1) is a human diabetes gene and transcription factor that is required for β cell function and survival during islet compensation for diet induced insulin resistance. We find Pdx1 in complex with Activating Transcription Factors (ATFs) which are well known to coordinate cellular stress responses. We hypothesize that PDX1, ATF4, and ATF5 form a stress responsive transcriptional regulatory complex that directs β cell fate under stress conditions. This will be tested in three Specific Aims: 1. Characterize the stress-induced PDX1 transcriptional complex, 2. Identify the transcriptional targets of the stress-induced PDX1 transcriptional complex, and 3. Elucidate the functional roles of PDX1 targets in β cell survival. We will employ cutting edge proteomic techniques to identify the components of the stress- induced PDX1 transcriptional complex and any associated post-translational modifications. Further, we will integrate ChIPExo and RNASeq profiles of mouse and human β cells under physiologically and pathophysiologically relevant stress to obtain a comprehensive genome wide identification of the transcriptional targets of this complex, leveraging the near base pair resolution of ChIP-Exo to resolve structurally distinct modes of transcription factor binding, thereby enabling new insights into stress responsive gene regulation in the beta cell. Finally, we will pursue the functional role of the Pdx1-Atf4-Atf5 target Gpt2 in primary mouse and human islets to test the hypothesis that the beta cell is metabolically reprogrammed by fuel excess in a manner analogous to what occurs during transformation of cancer cells. Together these results will describe new gene targets that regulate the cell fate decisions important for β cell survival in response to diabetes related stresses, and expand the translational applications for human diabetes of the PDX1 stress responsive transcriptional complex.