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的糖尿病进展的基础。β细胞是唯一的 由于对胰岛素生物合成的高需求而易受应激诱导的细胞死亡 分泌物和低抗氧化酶引起的氧化应激 活动。胰腺和十二指肠同源框1(PDX1)是人类糖尿病基因及其转录产物 饮食诱导的胰岛代偿过程中β细胞功能和存活所需的因子 胰岛素抵抗。我们在激活转录因子(ATF)的复合体中发现了Pdx1 是众所周知的协调细胞应激反应的物质。我们假设PDX1、ATF4和 ATF5形成一个应激反应转录调控复合体，指导β细胞在 压力条件。这将在三个具体目标上进行测试：1.描述应激诱导的 PDX1转录复合体，2.确定应激诱导的PDX1的转录靶点 转录复合体；3.阐明PDX1靶标在β细胞存活中的功能作用。 我们将使用尖端的蛋白质组学技术来确定压力的成分- 诱导的PDX1转录复合体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图谱 生理和病理生理相关的压力，以获得全面的基因组范围 利用近碱基对的分辨率鉴定该复合体的转录靶标 以解析转录因子结合的结构上不同的模式，从而使 对β细胞应激反应基因调控的新见解。最后，我们将继续推进 Pdx1-ATF4-Atf5靶向Gpt2在原代小鼠和人胰岛中的功能作用 假设β细胞被燃料过剩以类似的方式代谢重新编程 在癌细胞转化过程中发生了什么。综合起来，这些结果将描述新的 调控细胞命运决定的基因靶点对β细胞的生存至关重要 糖尿病相关压力，并扩大对人类糖尿病的翻译应用 PDX1应激反应转录复合体。

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.