Mechanisms of Intestinal Epithelial Differentiation

肠道上皮的适当分化几乎是肠道健康的各个方面的基础。例如, 上皮屏障功能不正常是炎症性肠病的关键因素，而且不正确 分化会导致末端消化和营养吸收不良，并增加癌症的易感性。 促进肠上皮细胞分化的转录因子是已知的，但存在缺口。 了解这些因素是如何与转录机制相互作用来驱动肠道分化的。 现在，新技术使测量染色质环事件和RNA聚合酶动力学成为可能 活着。这些过程在肠道中尚未被探索，可能具有肠道特有的机制。 我们工作的长期目标是解决和操纵肠道分化的机制；我们的 中心假设是，未探索的转录机制作为细胞动态调节 在肠道中分化。这些机制包括：1)增强子-启动子染色质环，2)RNA 聚合酶负荷，以及3)转录延长。该提案还将研究亲政府如何- 分化的BMP/Smad4信号通路与转录因子相交，驱动分化。 一种新的HNF4a和HNF4G转录因子的复合敲除导致严重干扰 肠道分化。ChIP-seq和rna-seq识别数百个在绒毛上被激活的基因。 分化依赖于HNF4的表达。这一新的转基因模型提供了一个严格的系统 应用新技术，明确推动分化的肠道调节机制。 这项提议的基本原理是发现肠道特异的转录调控机制，它可以 为了人类健康的利益而被剥削。新的转基因小鼠将被用来定义调控 激活体内分化基因所需的机制。AIM 1将应用新技术来解决 驱动分化的未知转录机制。目标2将探索肠道的新范式 通过BMP信号和HNF4因子的协同作用而分化。我们希望能找到新的 实现肠细胞分化的机制。 目标1和目标2很重要，因为它们可以帮助我们了解基因变异对增强子的影响， 确定新的协同调节剂，并导致改变肠道内环境平衡的治疗方法 与IBD、癌症和再生医学的治疗相关的分化。HNF4和Smad4 都与人类炎症性肠病和结肠癌密切相关。 拟议的研究在使用新的转基因模型、最先进的表观基因组学方面具有创新性。 方法和人类器官培养。创新的想法包括差异化控制的新范式 通过HNF4和BMP信号的协同努力，并提供了一个新的概念，通过它可以移动场 期待找到控制上皮细胞分化的治疗机会。

Proper differentiation of the intestinal epithelium underlies nearly all aspects of intestinal health. For example, improper epithelial barrier function is a critical contributor to inflammatory bowel diseases, and improper differentiation leads to poor terminal digestion and nutrient absorption, and increases susceptibility to cancers. Transcription factors that promote differentiation in the intestinal epithelium are known, but a gap exists in understanding how these factors interact with the transcriptional machinery to drive intestinal differentiation. New technologies now make it feasible to measure chromatin looping events and RNA Polymerase kinetics in vivo. These processes are unexplored in the intestine and likely to have intestine-specific mechanisms. The long term goal of our work is to resolve and manipulate the mechanisms of intestinal differentiation; our central hypothesis is that unexplored transcriptional mechanisms are dynamically regulated as cells differentiate in the intestine. These mechanisms include: 1) enhancer-promoter chromatin looping, 2) RNA polymerase loading, and 3) transcriptional elongation. The proposal will also examine how the pro- differentiation BMP/SMAD4 signaling pathway intersects with transcription factors to drive differentiation. A new, compound knockout of both HNF4A and HNF4G transcription factors leads to severe disruption of intestinal differentiation. ChIP-seq and RNA-seq identify hundreds of genes that are activated upon villus differentiation and depend upon HNF4 for expression. This novel transgenic model provides a rigorous system to apply new technologies and define intestinal regulatory mechanisms driving differentiation. The rationale of this proposal is to discover intestine-specific transcriptional regulatory mechanisms that can be exploited for the gain of human health. The novel transgenic mouse will be leveraged to define regulatory mechanisms required to activate differentiation genes in vivo. Aim 1 will apply new technologies to tackle unexplored transcriptional mechanisms driving differentiation. Aim 2 will explore a new paradigm for intestinal differentiation through the coordinated actions of BMP signaling and HNF4 factors. We expect to identify new mechanisms through which differentiation of enterocytes is achieved. Aims 1 & 2 are significant in that they can help us understand the impacts of genetic variants at enhancers, identify novel co-regulators, and lead to therapeutics that alter the homeostatic balance of intestinal differentiation that are relevant for treatments of IBD, cancer, and in regenerative medicine. HNF4 and SMAD4 are both strongly implicated in human IBD and Colon Cancer. The proposed research is innovative in the use of novel transgenic models, state-of-the-art epigenomics approaches, and human organoid cultures. Innovative ideas include the new paradigm of differentiation control by concerted efforts of HNF4 and BMP signaling, and provide a new concept through which the field can move forward to find therapeutic opportunities to control epithelial differentiation.