Epithelial-Mesenchymal Interactions in Gut Morphogenesis

描述(由申请人提供)：在肠道形态发生的个体发育过程中，上皮-间充质的相互作用是必需的，并且在上皮癌的发生中起关键作用。表吗啡是一种间充质/肌成纤维细胞蛋白，与分泌性囊泡停靠蛋白的合成素家族具有同源性。我们培育了表吗啡-/-(Epi-/-)小鼠，这些小鼠仍然存活，但小肠长度、粘膜表面积、隐窝细胞增殖和隐窝分裂都有所增加。EPI-/-小鼠对葡聚糖硫酸钠诱导的急性结肠炎有部分保护作用。我们的数据表明，Epi-/-小鼠的肠道表型来自骨形态发生蛋白(BMP)、WNT-β-连环蛋白和Hedgehog(HH)信号通路的影响。这与我们的观察一致，即衰老的Epi-/-小鼠小肠腺瘤性息肉的发病率显著增加，偶尔还会发展为浸润性癌症。假设1.表吗啡是肠道上皮细胞增殖的基质抑制因子，它通过直接调节BMPS和其他肌成纤维细胞生长因子的合成和/或分泌而发挥作用。2.表吗啡通过调节隐窝细胞的增殖和分裂来防止息肉的形成。3.表吗啡缺失通过减少间质BMP和其他生长因子的分泌，从而调节WNT-β-连环蛋白和HH信号通路，从而促进肠息肉的发生和癌变。4.表吗啡缺失可通过促进急性损伤后隐窝细胞的增殖来促进结肠上皮的修复。5.在损伤/慢性炎症性癌症模型中，长期丢失表吗啡将促进肿瘤的形成。具体目的是：1.确定表吗啡缺失如何导致隐窝细胞增殖增强和小肠息肉形成。2.通过肌成纤维细胞-上皮细胞共培养，阐明肌成纤维细胞抑制上皮细胞增殖的机制。3.确定表吗啡缺失减轻DSS诱导的损伤的机制，以及这是否增强了与DSS诱导的损伤/炎症相关的癌变。意义：我们有一个独特的小肠息肉形成和致癌模型，由单个肌成纤维细胞基因缺失产生。Epi-/-小鼠模型为调节隐窝细胞增殖、隐窝分裂和小肠息肉的形成提供了一个新的范例，并为我们提供了工具来确定肌成纤维细胞及其分泌产物在肠道上皮细胞动态平衡、癌变以及上皮损伤和修复过程中的作用。

DESCRIPTION (provided by applicant): Epithelial-mesenchymal interactions are required during ontogeny for gut morphogenesis and serve a critical role in epithelial carcinogenesis. Epimorphin is a mesenchymal/myofibroblast protein with homology to the syntaxin family of secretory vesicle docking proteins. We generated Epimorphin-/- (Epi-/-) mice, which are viable yet have increased small bowel length, mucosal surface area, crypt cell proliferation and crypt fission. Epi-/- mice were partially protected from acute colitis induced by dextran sodium sulfate. Our data suggest that the gut phenotype of the Epi-/- mouse derives from effects on bone morphogenetic protein (Bmp), wnt-¿- catenin and Hedgehog (Hh) signaling pathways. This is consistent with our observation that aged Epi-/- mice have a significantly increased incidence of small bowel adenomatous polyps, and occasionally develop invasive cancer. The hypotheses are 1. Epimorphin is a stromal inhibitor of epithelial proliferation in the gut, which acts by directly regulating synthesis and/or secretion of Bmps and other myofibroblast growth factors. 2. Epimorphin protects against polyp formation by modulating crypt cell proliferation and fission. 3. Epimorphin deletion predisposes to intestinal polyposis and carcinogenesis by reducing secretion of stromal Bmp and other growth factors, thus modulating wnt-¿-catenin and Hh signaling pathways. 4. Epimorphin deletion enhances colonic epithelial repair by increasing crypt cell proliferation after acute injury. 5. Long term loss of epimorphin will enhance tumor formation in an injury/chronic inflammation cancer model. The Specific Aims are: 1. Determine how epimorphin deletion leads to enhanced crypt cell proliferation and small intestinal polyp formation. 2. Clarify mechanisms by which myofibroblast epimorphin inhibits epithelial proliferation, using myofibroblast-epithelial co-cultures. 3. Determine mechanisms by which epimorphin deletion ameliorates injury induced by DSS, and whether this enhances carcinogenesis associated with DSS-induced injury/inflammation. Significance: we have a unique model of small bowel polyp formation and carcinogenesis, produced by deletion of a single myofibroblast gene. The Epi-/- mouse model has suggested a novel paradigm for the regulation of crypt cell proliferation, crypt fission, and small bowel polyp formation and has provided us with the tools to define the role of myofibroblasts and their secretory products in gut epithelial homeostasis, carcinogenesis and in epithelial injury and repair processes.