Wnt Pathway Regulation of Gastric Stem Cell Function

项目摘要 重新提交的新R 01申请提出定义胃干细胞调节的机制， 研究Wnt信号传导在维持组织稳态和促进上皮细胞增殖中的作用 在胃里。我们提出的研究与人类疾病直接相关，重点是 家族性腺瘤性息肉病（FAP）患者胃息肉形成。FAP是一种遗传性疾病 由于生殖系APC基因突变导致Wnt信号转导失调，伴有极胃肠（GI） 由Wnt促进干细胞增殖引起的增殖性疾病。尽管Wnt众所周知， 调节胃肠道干细胞，问题仍然是关于胃肠道不同区域对Wnt失调的敏感性 道。FAP患者的结肠表现是极端的，具有侵袭性疾病，其特征在于早期 腺瘤和癌症的发展，这通常导致结肠切除术在年轻的时候。的后果 胃干细胞中Wnt的失调还不太清楚，尽管息肉、腺瘤和癌 在FAP患者胃中的发育得到增强。值得注意的是，几乎所有的FAP患者都表现出频繁的 过度增生性息肉局限于胃的近端胃底/胃体区域，而相反， 胃的远端胃窦/幽门区域相对不受这些息肉的影响， 腺瘤样生长FAP突变对胃体干细胞和胃窦干细胞区域效应的基础， 胃组织反应未知。为了解决这个重要的问题，本项目的重点是定义Wnt 调节胃干细胞以揭示近端与远端通路激活的差异效应 胃我们将从功能和遗传学角度探讨胃FAP息肉形成的机制。 来自人FAP胃组织生物库的胃息肉和非息肉类器官和组织的分析 将作为本研究的组成部分构建的样本。人类FAP类器官研究将补充 小鼠遗传、药理学和类器官模型，以更深入地了解区域Wnt机制 调节胃干细胞。这些研究都是由“恰到好处的假设”，定义 基于区域特异性干细胞对不同水平的 Wnt激活。这些拟议的研究将共同确定Wnt信号转导失调如何导致 近端胃与远端胃中不同的胃上皮细胞增殖和息肉形成。这 这些信息将建立一个科学的框架，以帮助定义FAP患者的胃部表现。在 此外，这些研究将提供功能性见解，以加深对Wnt通路的理解 调节胃肠道干细胞。此外，了解Wnt途径调控的机制， 胃干细胞的功能对于完善在培养中增殖成体干细胞的策略是重要的， 再生疗法，以及制定诊断标准和潜在的治疗胃溃疡 过度增殖性疾病

PROJECT SUMMARY This resubmission of a new R01 application proposes to define mechanisms of gastric stem cell regulation, investigating the role of Wnt signaling to maintain tissue homeostasis and to promote epithelial cell proliferation in the stomach. Our proposed studies are directly relevant to human disease, focusing on mechanisms of gastric polyp formation in patients with familial adenomatous polyposis (FAP). FAP is a genetic disorder resulting from germline APC gene mutations that dysregulate Wnt signaling, with extreme gastrointestinal (GI) proliferative disease resulting from Wnt promotion of stem cell proliferation. Although Wnt is well known to regulate GI stem cells, questions remain regarding sensitivity to Wnt dysregulation in different regions of the GI tract. Colonic manifestations in FAP patients are extreme, with aggressive disease characterized by early adenoma and cancer development, which commonly leads to colectomy at a young age. The consequences of Wnt dysregulation in gastric stem cells is less well understood, although polyp, adenoma and cancer development are enhanced in the FAP patient stomach. Notably, almost all FAP patients exhibit frequent hyperproliferative polyps localized to the proximal fundic/corpus region of the stomach, while, in contrast, the distal antral/pylorus region of the stomach is relatively spared from these polyps and develops more occasional adenomatous growths. The basis for the regional effect of FAP mutations on corpus vs. antral stem cells and gastric tissue responses is unknown. To address this important question, this project focuses on defining Wnt regulation of gastric stem cells to uncover the differential effects of pathway activation in the proximal vs. distal stomach. We will pursue the mechanisms of FAP polyp formation in the stomach by functional and genetic analysis of gastric polyp and non-polyp organoids and tissues from a biobank of human FAP gastric tissue samples that will be built as a component of this study. Human FAP organoid studies will be complemented by mouse genetic, pharmacologic and organoid models to gain deeper mechanistic insight into regional Wnt regulation of gastric stem cells. The studies are framed by the “Just Right Hypothesis” which defines differential sensitivities along the GI tract based on region-specific stem cell responses to different levels of Wnt activation. Together the proposed studies will determine how dysregulated Wnt signaling leads to differential gastric epithelial cell proliferation and polyp formation in proximal vs. distal stomach. This information will establish a scientific framework to help define the gastric manifestations in FAP patients. In addition, the studies will provide functional insights to develop a deeper understanding of Wnt pathway regulation of gastrointestinal stem cells. Furthermore, understanding mechanisms of Wnt pathway regulation of gastric stem cell function is important to refine strategies to propagate adult stem cells in culture for regenerative therapies as well as to develop diagnostic criteria and potential therapies for gastric hyperproliferative diseases.