Transcriptional events controlling enteroendocrine cell differentiation

项目说明 肠内分泌细胞(EECS)是肠道中起源于肠道的五种上皮细胞系之一 干细胞。EECs以分泌多肽激素和生物胺而著称。隐秘产品 调节食物摄入量、能量平衡、胰岛素分泌和大多数消化器官的功能。 人们对驱动肠内分泌细胞分化的转录程序知之甚少。直到 最近，很难分离出足够的EEC用于基因表达分析，因为EEC代表的EEC少于 2%的肠上皮细胞。从转基因小鼠中收集荧光标记的EECs的能力 结合高通量测序的技术进步，使考虑基因成为可能 在EECS中以前无法完成的表达研究。两种基本螺旋环状螺旋转录因子 对欧共体的分化至关重要。神经原蛋白3(Neurogenin3，Neurog3)是EEC早期所必需的 规格，但可引起非内分泌细胞类型。BHLH蛋白NeuroD_1的表达 在所有的EEC中表达，限制细胞内分泌细胞的命运。作为一种相对较弱的转录激活因子， 目前尚不清楚NeuroD1是如何驱动细胞成为EECs的。我们的理解进一步受到匮乏的限制 肠内分泌细胞中已识别的NeuroD1靶点。越来越多的信息表明 组织特异性表达取决于局部染色质环境和增强子占有率 多种组织特异性转录因子。该提案的总体目标是确定NeuroD1 转录靶点，以确定占据NeuroD1附近位置的其他蛋白质，并确定如何 NeuroD1活性受局部染色质环境的影响。此外，无处不在的贡献 表达的转录因子结合到附近的位置，与NeuroD1的转录活性将被检测。这个 目标1的目标是在EECS中识别由NeuroD1激活的基因，并识别其他转录 与DNA结合的与NeuroD1紧密结合的因子，以增强靶基因的表达。AIM 2中的研究 将研究RREB1和LSD1的广泛作用，这两个成员是CtBP共抑制物复合体的两个成员 与NeuroD1联合增强转录。目标3的目标是确定开放的重要性 NeuroD1驱动的组织特异性染色质亚型和多种转录因子对增强子的占有率 基因表达。Aim3的最终目标将是确定是否有任何已发现的NeuroD1增强子簇 与GWAS目录中的疾病相关变异(SNPs)相关联。建议的研究完成后， 扩大我们对肠内分泌细胞分化及其对常见疾病的潜在影响的知识 糖尿病和肥胖症等疾病。

Project Description Enteroendocrine cells (EECs) are one of five epithelial cell lineages in the intestine that arise from intestinal stem cells. EECs are notable for their secretion of peptide hormones and biogenic amines. Secreted products regulate food intake, energy homeostasis, insulin secretion and the function of most digestive organs. Relatively little is known about the transcriptional programs that drive enteroendocrine cell differentiation. Until recently, it has difficult to isolate enough EECs for gene expression analysis since EECs represent less than 2% of the intestinal epithelium. The ability to collect fluorescently labeled EECs from transgenic mice combined with technological improvements in high throughput sequencing, make it possible to consider gene expression studies in EECs that previously could not be done. Two basic helix loop helix transcription factors are critical for EEC differentiation. Neurogenin3 (Neurog3) is required for the earliest stages of EEC specification but can give rise to nonendocrine cell types. Expression of the bHLH protein NeuroD1 is expressed in all EECs, restricting cells to an endocrine cell fate. As a relatively weak transcriptional activator, it is not known how NeuroD1 drives cells to become EECs. Our understanding is further limited by the paucity of identified NeuroD1 targets in enteroendocrine cells. An increasing body of information has revealed that tissue specific expression depends on both the local chromatin environment and enhancer occupancy by multiple tissue specific transcription factors. The overall goals of this proposal are to identify NeuroD1 transcriptional targets, to identify other proteins that occupy sites close to NeuroD1, and determine how NeuroD1 activity is influenced by the local chromatin environment. In addition, the contribution of ubiquitously expressed transcription factors bound to nearby sites, to NeuroD1 transcriptional activity will be examined. The goal of Aim 1 is to identify genes that are activated by NeuroD1 in EECs and to identify other transcription factors that bind to DNA in close proximity with NeuroD1 to enhance target gene expression. Studies in Aim 2 will examine the broad role of RREB1 and LSD1, two members of the CtBP co-repressor complex that associate with NeuroD1 to potentiate transcription. The goal of Aim 3 is to determine the importance open chromatin subtypes and enhancer occupancy by multiple transcription factors in NeuroD1 driven tissue specific gene expression. The final goal of Aim3 will be to determine if any identified NeuroD1 enhancer clusters are linked to disease associated variants (SNPs) in the GWAS catalogue. Completion of the proposed studies will expand our knowledge about enteroendocrine cell differentiation and their potential impact on common diseases like diabetes and obesity.