Cellular and molecular characterization of the digestive tract sub-epithelium

项目描述 消化道上皮细胞的发育、完整性和更新依赖于来自相邻细胞的信号。 间充质细胞和缺陷的信号传导可能是疾病的基础，如炎症性肠病， 疾病、感染病理反应、吸收不良和癌症。关键的间质信号 包括Wnt因子和骨形态发生蛋白（BMP）激动剂和拮抗剂，以及最近研究 提示多种（CD 34+、Foxl 1+、PDGFRA+、Gli 1+）细胞类型为可能的来源。然而，精确 这些人群的身份、重叠和需求仍不清楚。综合考虑高- 分辨率显微解剖学，不同标记物定义的细胞的分子特征分析，以及单细胞RNA 分析使我们鉴定出小鼠小肠中3种不同的间充质细胞类型。细胞 表达高血小板衍生生长因子受体A（PDGFRAhi）的细胞最靠近上皮， 对应于最近描述的Foxl 1+端细胞。这些细胞表达丰富的骨形成蛋白， 特别是在隐窝-绒毛连接处，而两个PDGFRAlo细胞群在解剖学上和 分子上不同的：那些位于隐窝干细胞区附近的独特的共表达PDGFRA， 四跨膜蛋白CD 81和BMP拮抗剂Gremlin 1，以及缺乏表面的绒毛固有层中的细胞 CD81。这些数据共同提出了一个新的假设，即重要的隐窝-绒毛BMP梯度反映了 绒毛基部的激动剂和隐窝基部的拮抗剂的密集来源。具体目标1将测试这一点 假设，并进一步解决间充质PDGFRAhi的独特特征和功能， 小鼠小肠中的PDGFRAlo细胞。基于未分级PDGFRAlo的初步数据， 细胞支持ISCs的体外扩增，我们将研究胞膜内分泌的可能相反的功能。 CD 81+和绒毛CD 81-亚群。为了应对ISC损伤，间充质触发隐窝 这可能是通过维持未损伤的ISC的相同可溶性因子。目的2 提出了一个系统的，公正的方法，以确定具体的细胞来源的关键恢复 信号.我们还将检验间充质PDGFRAhi和PDGFRAlo细胞依赖于PDGFRAlo表达的假设。 肠上皮提供不同浓度的配体PDGFA，用于它们的存活，增殖， 和不同的生理功能。ISC和隐窝祖细胞在胃上皮中具有对应物， 其翻转更慢，更少地依赖于Wnt信号传导，并且不延伸绒毛。充质 PDGFRA+细胞在两个器官中同样丰富，在以下方面可能具有重要的相似性和差异： 组织和职能。为了更好地了解胃干/祖细胞的控制和潜在的 在这两个器官的信号逻辑，目的3将表征胃间充质PDGFRA+细胞在相同的 我们在肠道中达到的深度。总之，这些研究应用了创新的实验 方法来检查解决消化道生物学的基本问题的具体假设。

Project Description Epithelial development, integrity, and turnover in the digestive tract depend on signals from adjacent mesenchymal cells, and defective signaling may underlie aspects of disorders such as Inflammatory Bowel Disease, pathologic response to infection, malabsorption, and cancer. Crucial mesenchymal signals include Wnt factors and bone morphogenetic protein (BMP) agonists and antagonists, and recent research implicates various (CD34+, Foxl1+, PDGFRA+, Gli1+) cell types as possible sources. However, the precise identities, overlap, and requirements of these populations remain unclear. Integrated consideration of high- resolution microscopic anatomy, molecular profiling of diverse marker-defined cells, and single-cell RNA analysis has led us to identify 3 distinct mesenchymal cell types in the mouse small intestine. Cells expressing high platelet-derived growth factor receptor A (PDGFRAhi) lie closest to the epithelium and correspond to recently described Foxl1+ telocytes. These cells express abundant BMPs and congregate particularly at the crypt-villus junction, whereas two PDGFRAlo cell populations are anatomically and molecularly distinct: those located near the crypt stem-cell zone that uniquely co-express PDGFRA, tetraspanin CD81, and the BMP antagonist Gremlin1, and cells in the villus lamina propria that lack surface CD81. These data collectively suggest the novel hypothesis that crucial crypt-villus BMP gradients reflect dense sources of agonists at the villus base and antagonists at the crypt base. Specific Aim 1 will test this hypothesis and further resolve the distinctive features and functions of mesenchymal PDGFRAhi and PDGFRAlo cells in the mouse small intestine. Building on preliminary data that unfractionated PDGFRAlo cells support expansion of ISCs in vitro, we will investigate the possibly opposing functions of pericryptal CD81+ and villus CD81- subpopulations. In response to ISC damage, the mesenchyme triggers crypt progenitors to dedifferentiate, likely through the same soluble factors that maintain uninjured ISC. Aim 2 proposes a systematic, unbiased approach to identify the specific cellular sources of key restitutional signals. We will also test the hypothesis that mesenchymal PDGFRAhi and PDGFRAlo cells depend on the intestinal epithelium to provide varying concentrations of the ligand PDGFA for their survival, proliferation, and distinct physiologic functions. ISC and crypt progenitors have counterparts in the stomach epithelium, which turns over more slowly, depends less on Wnt signaling, and does not extend villi. Mesenchymal PDGFRA+ cells are equally abundant in both organs, with likely important similarities and differences in organization and functions. To better understand gastric stem/progenitor cell control and the underlying signaling logic in both organs, Aim 3 will characterize stomach mesenchymal PDGFRA+ cells in the same depth that we have achieved in the intestine. Together, these studies apply innovative experimental approaches to examine specific hypotheses that address fundamental questions in digestive tract biology.