Investigating a master regulator of large intestine stem cells

项目总结 结肠是肠道的主要部分，在以下方面与小肠有很大不同 形态、细胞类型、生理功能和疾病易感性。毁灭性的和普遍的 疾病，包括结直肠癌和溃疡性结肠炎，由结肠而不是小肠引起。 结肠吸收水分，但不能吸收大部分营养物质，如小肠，因此 严重的小肠缺失会导致消化衰竭，而结肠无法弥补。 尽管取得了重大进展，但对结肠生物学的各个方面仍然知之甚少。分子 区分结肠和小肠并支配结肠特异细胞谱系的决定因素 分化和动态平衡在很大程度上仍然没有特征，阻碍了对 将肠道疾病区域化。在初步研究中，我们鉴定了SATB2，一种染色质因子 在结肠上皮的限制性表达，作为结肠识别和识别的关键分子调节因子 差异化。成人肠道SATB2缺失导致结肠的同源异型性转化 在细胞组成和基因表达上类似于小肠回肠的上皮细胞， 突变的结肠可以吸收营养，这是小肠独有的功能。这些数据 提示SATB2是一种潜在的结肠上皮“主调节器”。SATB2的鉴定 提供了一个独特的机会来研究结肠个体发育和命运决定，并评估其 治疗方面的影响。在这个项目中，目标1将评估结肠干细胞的假设 港湾预涂回肠增强剂，因此对回肠具有染色质水平的通透性 转录激活和细胞命运可塑性。Aim 2研究将评估SATB2的假设 招募两个染色质重塑因子，MTA2和SMARCD2，以分离结肠和 回肠增强剂修饰局部染色质，允许肠道转录因子的差异化访问 并实现转录调控。在目标3中，使用短肠综合征的小鼠模型 (SBS)，我们将评估促进结肠营养吸收是否可以对抗消化衰竭 以及与SBS相关的病理生理学。这些研究将共同阐明细胞和 SATB2保留结肠特性和影响结肠回肠的分子机制 转化，可作为治疗SBS的一种新方法。

PROJECT SUMMARY The colon is a major segment of the intestine and differs significantly from the small intestine in morphology, cell types, physiological function and disease susceptibility. Devastating and prevalent diseases, including colorectal cancers and ulcerative colitis, arise from colon but not small intestine. Colon absorbs water but cannot uptake most nutrients like the small intestine and consequently a significant loss of the small intestine will lead to digestive failure that the colon cannot compensate. Despite significant progress, aspects of the colon biology remain poorly understood. Molecular determinants that distinguish the colon from the small intestine and govern colon-specific cell lineage differentiation and homeostasis remain largely uncharacterized, hindering a deeper understanding of regionalized intestinal diseases. In preliminary studies, we identified SATB2, a chromatin factor with restricted expression in the colonic epithelium, as a crucial molecular regulator of colon identity and differentiation. SATB2 deletion from adult intestine led to a homeotic-like transformation of colonic epithelium into one that resembles small intestine ileum in cellular composition and gene expression, and the mutant colon can absorb nutrients, a function unique to the small intestine. These data suggest that SATB2 is a potential “master regulator” of colonic epithelium. The identification of SATB2 offers a unique opportunity to study colonic ontogeny and fate determination, and assess its therapeutic implications. In this project, Aim 1 will evaluate the hypothesis that colonic stem cells harbor primed ileal enhancers and thus harbor a chromatin-level permissiveness for ileal transcriptional activation and cell fate plasticity. Aim 2 studies will evaluate the hypothesis that SATB2 recruits two chromatin remodeling factors, MTA2 and SMARCD2, to separate pools of colonic and ileal enhancers to modify local chromatin, allowing differential access of intestinal transcription factors and effecting transcriptional regulation. In Aim 3, using mouse models of Short bowel syndrome (SBS), we will evaluate whether promoting colonic nutrient absorption can combat digestive failure and the associated pathophysiology in SBS. These studies together will elucidate the cellular and molecular mechanisms by which SATB2 preserves colonic identity and effects a colonic to ileal conversion, which may be exploited as a novel therapeutic approach to treat SBS.