Mechanisms underlying YY1 control of intestinal epithelial homeostasis

描述（由申请人提供）：在肠上皮中，介导增殖和分化之间平衡作用的调节机制尚未完全确定，但对于维持正常稳态及其从疾病中恢复至关重要。肠上皮细胞的体内平衡需要精确的调节：过度增殖可导致肿瘤形成，但增殖不足会导致组织塌陷。本申请的目的是通过研究一种意想不到的转录因子在这一过程中的重要作用来弥合我们对肠道稳态理解的差距。初步研究表明，成年小鼠肠上皮中转录因子YY 1的失活引发上皮稳态的严重失衡：祖细胞群体扩张，而分化的群体收缩。因此，确定YY 1如何控制上皮更新可以提供一个新的治疗切入点，在恢复疾病的上皮稳态。这个项目的第一个目标是测试3个合理的，非排他性的解释 对于缺乏YY 1的肠上皮细胞中增殖的隐窝细胞的增加：1）YY 1控制干细胞更新，2）YY 1控制隐窝细胞增殖，或3）YY 1介导细胞周期停滞和终末分化。小鼠遗传学和组织学方法将测量YY 1丢失后的上皮细胞群体和行为。这个目标的完成应该定义YY 1维持内稳态平衡的特定过程。该项目的第二个目标是确定YY 1控制上皮细胞周转的转录调控机制。ChIP-seq将用于绘制YY 1与分离的肠上皮细胞群体基因组的相互作用。YY 1的基因组结合位置的鉴定将使我们能够确定其直接的调节靶基因，确定其调节伴侣转录因子，并确定YY 1是否在活性或抑制的染色质结构中运作。这些分析将与YY 1敲除的基因表达分析整合，并通过从当前K 01收集的染色质ChIP-seq数据进行补充。拟议的研究是创新的，因为它有望揭示一种新的，YY 1依赖的调节机制，通过使用尖端的表观基因组技术来管理增殖/分化决定。完成拟议的工作将揭示新的机制下的稳态细胞周转，并应具有重要价值的领域，如伤口愈合和肿瘤发生。最后，正如R 03机制的目的一样，为该项目提供资金应能提高获得K 01奖的研究人员开展研究的能力。建立新的调查人员加入对抗肠道疾病的斗争是NIDDK的优先事项，作为解决该国最大的医疗问题之一的长期目标的一部分。YY 1调控机制的研究非常适合于这一目的，因为它可以在很短的时间内完成，但我可能会打开一个新的研究领域的肠上皮更新的机制。

DESCRIPTION (provided by applicant): In the intestinal epithelium, the regulatory mechanisms that mediate the balancing act between proliferation and differentiation are incompletely defined, but are critical for maintaining normal homeostasis and its recovery from disease. Intestinal epithelial homoeostasis requires precise regulation: excess proliferation can lead to tumor formation, but insufficient proliferation would cause tissue collapse. The objective of this application is to bridge the gap in our understanding of intestinal homeostasis by investigating an unexpected transcription factor's essential role in this process. Preliminary studies show that inactivation of the transcription factor YY1 in the adult murine intestinal epithelium triggers massive imbalance of epithelial homeostasis: the progenitor population expands while the differentiated population contracts. Therefore, defining how YY1 controls epithelial turnover could provide a novel therapeutic entry point in restoring epithelial homeostasis in disease. This project's first Aim is to test 3 plausible, non-exclusive explanations for the increase in proliferating crypt cells in intestinal epithelia lacking YY1: 1) YY1 controls stem cell turnover, 2) YY1 controls crypt cell proliferation, or 3) YY1 mediates cell cycle arrest and terminal differentiation. Mouse genetic and histological approaches will measure epithelial cell populations and behaviors upon YY1 loss. Completion of this aim should define the specific process(es) by which YY1 maintains homeostatic balance. The second Aim of the project will define the transcriptional regulatory mechanisms underlying YY1's control of epithelial turnover. ChIP-seq will be employed to map YY1 interactions with the genome of isolated intestinal epithelial cell populations. Identification of YY1's genomic binding locations will allow us to identify its direct regulatory target genes, identify its regulatory partner transcription factors,and determine whether YY1 operates in active or repressed chromatin structure. These analyses will be integrated with gene expression analysis of the YY1 knockout, and complemented by chromatin ChIP-seq data collected from the current K01. The proposed research is innovative in that it is expected to reveal a novel, YY1-dependent regulatory mechanism governing the proliferation/differentiation decision by using cutting-edge epigenomic technologies. Completion of the proposed work will reveal new mechanisms underlying homeostatic cell turnover and should be of significant value to fields as diverse as wound healing and oncogenesis. Finally, as is intended for this R03 mechanism, funding this project should enhance the capability of the K01-awarded investigator to conduct research. Establishing new investigators to join the fight against intestinal disease is a priority for the NIDDK as part of a long-term goal to solve one of the Country's largest medical problems. The proposed research on the regulatory mechanisms of YY1 is perfectly suited for this purpose in that it can be completed in a short timeframe, yet i likely to open a new area of research on the mechanisms of intestinal epithelial renewal.