Defining the molecular mechanisms driving intestinal epithelial cell specification

肠道上皮是一个动态系统，在整个生物体的生命过程中不断地、快速地再生。这种上皮由隐窝和绒毛隔间组成，具有不同的细胞群和功能。肠隐窝含有上皮干细胞，周围环绕着分化的潘氏细胞。这些后者的细胞表达促进生长和细胞保护的多肽，以确保从干细胞产生最佳的祖细胞。肠绒毛含有分化的肠上皮细胞亚型，包括肠细胞、杯状细胞和肠内分泌细胞。尽管在过去的几年里已经收集了一些关于在这种特殊情况下上皮细胞规范和维持所需的分子机制的性质的线索，但涉及的确切调控电路仍然没有很好的定义。此次Discovery Grant的续签旨在推进这一研究计划，并提议在未来五年内整合一系列蛋白质之间的互动转录网络，其中包括我们在过去几年中研究的一些蛋白质。更准确地说，我们拟议的工作将集中在GATA4转录因子上，我们最近发现了GATA4转录因子的特定新的肠上皮细胞功能，以期随着其他相关转录调控因子的发现，对其转录和生物学综合影响。我们还打算利用我们最近在实验室优化的创新系统模型。这个生物系统由体外生长的微小上皮肠组成，完美地概括了肠上皮的增殖和细胞分化。本研究旨在明确GATA4蛋白复合体在干细胞和分化细胞中调节肠上皮转录组的易感性，并结合最相关的相互作用转录调控因子(S)，确定GATA4的全球肠上皮遗传靶点。我们希望这些策略将为上皮干细胞和分化细胞中上皮细胞特异性转录相互作用组(S)的性质提供关键信息。这将使人们更好地了解对肠上皮细胞规范至关重要的调控因子的性质，并可能提供新的长期靶向策略，以替代产生丰富和特定亚型的肠上皮细胞的独特培养集，这些模型仍有待优化。

The intestinal epithelium is a dynamic system that constantly and rapidly regenerates throughout the organism life. This epithelium is organized in crypt and villus compartments harbouring distinct cell populations and functions. Intestinal crypts contain epithelial stem cells surrounded by differentiated Paneth cells. These latter cells express growth-promoting and cell-protective peptides to ensure optimal production of progenitors from the stem cells. Intestinal villi contain differentiated subtypes of epithelial cells including enterocytes, goblet and enteroendocrine cells. Although some clues have been collected over the past years on the nature of the molecular mechanisms that are required for epithelial cell specification and maintenance in this particular context, the exact regulatory circuit involved is still not well defined. This renewal of Discovery Grant intends to pursue this program of research and proposes to integrate, over the next five years, the interactive transcriptional network between a set of proteins including some of which we have studied over the past years. More precisely, our proposed work will focus on the GATA4 transcription factor, for which we have recently identified specific novel intestinal epithelial cell functions, toward its integrated transcriptional and biological impact with the discovery of other relevant transcriptional regulators. We also intend to take advantage of an innovative system model that we have recently optimized in the laboratory. This biological system consists of mini epithelial guts growing ex vivo that perfectly recapitulate proliferation and cytodifferentiation of the intestinal epithelium. This research program will aim to define the nature of GATA4 protein complexes susceptible to regulate the intestinal epithelial transcriptome in stem and differentiated cells and to define the global intestinal epithelial genetic targets of GATA4 in combination to most relevant identified interacting transcription regulator(s). It is our hope that these strategies will provide crucial information on the nature of the epithelial cell specific transcriptional interactome(s) in both epithelial stem and differentiated cells. This will allow a better understanding of the nature of regulators important for intestinal epithelial cell specification and perhaps provide novel long-term targeting strategies to alternatively produce unique culture sets of enriched and specific subtypes of intestinal epithelial cells, models that still await to be optimized.