Decoding LRH-1 Activity in Gut Regeneration and Differentiation

项目摘要/摘要 背景： 肠道中的初级上皮干细胞已经被知道了十多年，导致了重要的 上皮更新和损伤修复的观察。这些基础性研究表明， 肠上皮是在隐窝底部的干性和分化为 粘膜表面，具有复杂的信号网络，影响分化的茎和命运 祖细胞。几个研究小组现在已经表明，破坏肠道干细胞和/或广泛 上皮损伤可以通过祖细胞的去分化来修复。因此，两者之间的平衡 茎和分化可以通过尚不明确的分子机制来解释。 我们发现核受体肝脏受体Homolog-1(LRH-1；NR5A2)对两者都是必不可少的 干细胞维持和指导高度专业化的肠内分泌细胞谱系的分化。 因此，这种不寻常的转录因子具有促进干细胞和细胞分化的双重作用，使其 是阐明肠道上皮细胞更新和愈合机制的一个有吸引力的靶点。 方法： 在这个应用中，我们将1)确定LRH-1在上皮修复和干细胞重建中的作用 肠炎模型，2)确定LRH-1的SUMO化如何调节干和祖细胞的受体功能 细胞，以及3)确定和验证细胞特异性肠道LRH-1“靶点组”。我们将通过以下方式实现这一目标 使用血统追踪的小鼠模型和肠道器官平台的新实现。 在我们的目标成功完成后，我们将机械地评估一项 可药物核受体用于1)平衡干细胞更新、分化和受损的修复 2)提供了有史以来第一次对肠道中Sumoylated LRH-1的详细评估，以及3)产生了 真正的LRH-1肠道靶点对受体药物的开发将是无价的。 目标： 这项建议旨在扩大我资助的K08调查期间发现的一个关键发现，并 推进我们对肠道如何在正常和 疾病缠身的国家。这项工作的基础是我们的假设，即LRH-1在唯一的 干细胞和祖细胞中的细胞环境同时驱动支持细胞的不同基因程序 更新和特化细胞分化。我们的实验旨在最大限度地利用 LRH-1框架下的肠上皮生理学和核受体生物学的非凡融合。

Project Summary/Abstract Background: The primary epithelial stem cell in the intestine has been known for over a decade, leading to important observations in epithelial renewal and injury recovery. These fundamental studies have demonstrated that the intestinal epithelium is a balanced continuum between stemness in the crypt base and differentiation towards the mucosal surface, with complex signaling networks influencing stemness and fate of the differentiating progenitor cells. Several groups have now shown that destruction of intestinal stem cells and/or extensive epithelial damage can be repaired by the dedifferentiation of progenitor cells. Thus, the balance between stemness and differentiation can be tipped by as yet undefined molecular mechanisms. We discovered that the nuclear receptor Liver Receptor Homolog-1 (LRH-1; NR5A2) is essential for both stem cell maintenance and for directing differentiation of the highly specialized enteroendocrine cell lineage. Therefore, this unusual transcription factor has dual roles promoting stemness and cell differentiation, making it an attractive target for elucidating the mechanisms responsible for gut epithelial renewal and healing. Approach: In this application, we will 1) determine the contribution of LRH-1 to epithelial repair and stem cell restitution in enteritis models, 2) determine how SUMOylation of LRH-1 modulates receptor function in stem and progenitor cells, and 3) determine and validate the cell-specific gut LRH-1 “targetome.” We will accomplish this through the use of lineage-traced mouse models and novel implementations of the intestinal organoid platform. Following successful completion of our aims, we will have mechanistically evaluated the contribution of a druggable nuclear receptor to 1) balancing stem cell renewal, differentiation, and restitution of damaged epithelium 2) provided the first ever detailed evaluation of SUMOylated LRH-1 in the gut, and 3) generated a bona fide LRH-1 gut targetome that will be invaluable for receptor drug development. Goals: This proposal is designed to expand upon a key finding uncovered during my funded K08 investigation and advance our mechanistic understanding of how the gut balances stemness vs differentiation during normal and diseased states. Underlying this work is our hypothesis that LRH-1 is differentially modulated within unique cellular contexts in stem and progenitor cells to drive diverse gene programs simultaneously supporting cell renewal and specialized cell differentiation. Our experiments are designed to maximally exploit the extraordinary confluence of intestinal epithelial physiology and nuclear receptor biology framed by LRH-1.