Fritsch Christine, Swietlicki Elzbieta A, Lefebvre Olivier, Kedinger Michele, Iordanov Hristo, Levin Marc S, Rubin Deborah C
Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.
J Clin Invest. 2002 Dec;110(11):1629-41. doi: 10.1172/JCI13588.
The formation of the crypt-villus axis during gut ontogeny requires continued reciprocal interactions between the endoderm and mesenchyme. Epimorphin/syntaxin 2 (epimorphin) is a mesenchymal protein expressed in the fetal gastrointestinal tract during villus morphogenesis. To elucidate its role in gut ontogeny, the epimorphin cDNA was transfected, in sense and antisense orientations, into a rat intestinal myofibroblast cell line, MIC 216. To determine the effects of epimorphin on the epithelium, myofibroblasts were cocultured with the Caco2 cell line. Caco2 cells spread in a simple monolayer over antisense-transfected cells lacking epimorphin. In contrast, sense-transfected myofibroblasts induced Caco2 cells to form compact, round clusters with small lumens. These morphologic differences were preserved in Transwell cocultures in which cell-cell contact was prevented, suggesting that epimorphin's effects were mediated by secreted factor(s). To determine the effects of epimorphin on crypt-villus axis formation in an in vivo model, rat gut endoderm was combined with epimorphin-transfected myofibroblasts and implanted into the chick intracoelomic cavity. The grafts in which epimorphin was overexpressed revealed multiple well-formed villi with crypt-like units, whereas those in which epimorphin expression was inhibited developed into round cystic structures without crypts or villi. Of several potential secreted morphogens, only the expression of bone morphogenetic protein 4 (Bmp4) was increased in the epimorphin-transfected cells. Incubation with noggin partially blocked the transfected myofibroblasts' effects on Caco2 colony morphology. These results indicate that mesenchymal epimorphin has profound effects on crypt-villus morphogenesis, mediated in part by secreted factor(s) including the Bmp's.
肠道个体发育过程中隐窝 - 绒毛轴的形成需要内胚层和间充质之间持续的相互作用。上皮形态发生素/ syntaxin 2（上皮形态发生素）是一种在绒毛形态发生过程中于胎儿胃肠道表达的间充质蛋白。为了阐明其在肠道个体发育中的作用，将上皮形态发生素cDNA以正义和反义方向转染到大鼠肠道肌成纤维细胞系MIC 216中。为了确定上皮形态发生素对上皮的影响，将肌成纤维细胞与Caco2细胞系共培养。Caco2细胞在缺乏上皮形态发生素的反义转染细胞上呈简单单层铺展。相反，正义转染的肌成纤维细胞诱导Caco2细胞形成紧密的圆形簇，管腔较小。这些形态学差异在防止细胞 - 细胞接触的Transwell共培养中得以保留，表明上皮形态发生素的作用是由分泌因子介导的。为了确定上皮形态发生素在体内模型中对隐窝 - 绒毛轴形成的影响，将大鼠肠道内胚层与上皮形态发生素转染的肌成纤维细胞结合并植入鸡的体腔。上皮形态发生素过表达的移植物显示出多个具有隐窝样单位的发育良好的绒毛，而那些上皮形态发生素表达受到抑制的移植物则发育成没有隐窝或绒毛的圆形囊性结构。在几种潜在的分泌形态发生素中，只有骨形态发生蛋白4（Bmp4）的表达在上皮形态发生素转染的细胞中增加。用诺金蛋白孵育部分阻断了转染的肌成纤维细胞对Caco2集落形态的影响。这些结果表明，间充质上皮形态发生素对隐窝 - 绒毛形态发生有深远影响，部分由包括Bmp在内的分泌因子介导。
