Transcriptional events controlling enteroendocrine cell differentiation

项目描述 肠内分泌细胞（EECs）是肠道中的五种上皮细胞谱系之一，其来源于肠上皮细胞。 干细胞值得注意的是，内皮细胞分泌肽激素和生物胺。分泌产物 调节食物摄入、能量平衡、胰岛素分泌和大多数消化器官的功能。 相对而言，我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，由于EECs代表的基因表达少于 2%的肠上皮。从转基因小鼠中收集荧光标记的内皮细胞的能力 结合高通量测序的技术改进，使考虑基因 在EECs中的表达研究，以前不能做。两种基本螺旋环螺旋转录因子 对EEC分化至关重要。神经生成素3（Neurog3）是EEC最早期所必需的 但可以产生非内分泌细胞类型。bHLH蛋白NeuroD1的表达是 在所有内皮细胞中表达，将细胞限制为内分泌细胞命运。作为一种相对较弱的转录激活因子， NeuroD1是如何驱动细胞成为EECs的尚不清楚。我们的理解进一步受到缺乏 在肠内分泌细胞中鉴定的NeuroD1靶点。越来越多的信息表明， 组织特异性表达依赖于局部染色质环境和增强子占据， 多种组织特异性转录因子。本提案的总体目标是确定NeuroD1 转录靶点，以确定其他蛋白质占据的网站接近NeuroD1，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 将检测与附近位点结合的表达的转录因子对NeuroD1转录活性的影响。的 目的1的目标是鉴定在EECs中由NeuroD1激活的基因，并鉴定其他转录 与NeuroD1紧密结合的DNA因子，以增强靶基因表达。研究目的2 将研究RREB1和LSD1的广泛作用，这两个CtBP共阻遏复合物的成员， 与NeuroD1结合以增强转录。目标3的目标是确定 在NeuroD1驱动的组织特异性中，多种转录因子的染色质亚型和增强子占据 基因表达Aim3的最终目标将是确定是否有任何识别的NeuroD1增强子簇， 与GWAS目录中的疾病相关变异（SNP）相关。完成拟议的研究将 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认识。 比如糖尿病和肥胖症。

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.