Cdx in GI Differentiation and Transdifferentiation

描述(申请人摘要)：多个基因的复杂相互作用 在内胚层和中胚层中的表达是分化和 胃肠道的发育。专门性与独特性 食道、胃、肠和结肠的上皮细胞起源于 胚胎发生过程中的内胚层。这些器官的独特特征是 通常在一生中保持，然而，转分化或肠道 发生肠型粘膜上皮化生可发生在食道或 胃。这一重要的人类癌前病变的起源尚不清楚，但 具有明显的临床相关性。CDX1和CDX2，肠特异性同源异型盒 转录因子，是指导发育的候选基因， 肠道表型的分化和维持。此外，CDX1 CDX2虽然在正常胃或食道中不表达，但 表达于胃和食道粘膜的肠化生。这个 研究人员假设CDX1和CDX2指导转分化 发生在肠化生中的程序。这一假设将会得到解决。 通过相互关联的特定目标，利用转基因小鼠模型来探索 CDX1和CDX2在发育胃和成人胃中的作用 通过这两个基因的错误表达导致的食道上皮细胞。具体目标1 检测CDX表达在早期胚胎发育中的生物学后果。 Cdx1和Cdx2的编码区将置于 HNF3Gamma顺式调控元件，将指导CDX1的异位表达 或转基因小鼠发育胃内胚层中的CDX2。这个 申请人已经通过这种方法成功地表达了CDX2，并且已经 肠型细胞的证据。《特定目标2》利用第二种转基因技术 用小鼠模型研究CDX表达对分化成纤维细胞的影响 放置CDX1或CDX2编码区的食道和胃粘膜 在四环素可诱导启动子的控制下。两者的表型 转基因模型将被检查形态和基因的变化。 表情。肠道特异基因的表达将被确定和 后续的分析将包括消减杂交进行详细研究 在表达转基因的组织中差异表达的基因。在……里面 此外，由于肠化生是人类的一种癌前状态， 将对动物进行癌症易感性增加的评估。总而言之， 这个项目的总体目标是阐明cdxl的生物学作用。 和CDX2在肠化生中的作用及其分子机制 Cdx1和cdx2诱导的转分化程序。

DESCRIPTION (Applicant's Abstract): Complex interactions of multiple genes expressed in the endoderm and mesoderm are necessary for differentiation and development of the gastrointestinal tract. The specialized and distinct epithelia of the esophagus, stomach, intestine and colon arise from the endoderm during embryogenesis. The unique characteristics of these organs are usually maintained throughout life, however, transdifferentiation or intestinal metaplasia can occur in which intestinal-type mucosa arises in the esophagus or stomach. The origin of this important human premalignant lesion is unknown but of clear clinical relevance. CDX1 and CDX2, intestine specific homeobox transcription factors, are candidate genes for directing development, differentiation and the maintenance of the intestinal phenotype. Moreover, CDX1 and CDX2, although not expressed in the normal stomach or esophagus, are expressed in intestinal metaplasia of the gastric and esophageal mucosa. The investigator hypothesizes that CDX1 and CDX2 direct the transdifferentiation program that occurs in intestinal metaplasia. This hypothesis will be addressed by interrelated specific aims, which employ transgenic mouse models to explore the effects of Cdxl and Cdx2 in the developing stomach and adult gastric and esophageal epithelia through misexpression of both genes. Specific aim 1 examines the biological consequences of Cdx expression in early embryogenesis. The coding regions of Cdxl and Cdx2 will be placed under the control of Hnf3gamma cis-regulatory elements, which will direct ectopic expression of Cdxl or Cdx2 in the endoderm of the developing stomach of transgenic mice. The applicant has already successfully expressed Cdx2 by this method and has evidence of intestinal type cells. Specific aim 2 utilizes a second transgenic mouse model to define the effect of Cdx expression on the differentiated esophageal and gastric mucosa by placing the coding regions of Cdxl or Cdx2 under the control of a tetracycline inducible promoter. The phenotype of both transgenic models will be examined for changes in morphology and gene expression. The expression of intestine specific genes will be determined and subsequent analysis will include subtractive hybridization to study in detail genes that are differentially expressed in tissue expressing the transgene. In addition, as intestinal metaplasia is a premalignant condition in humans, the animals will be assessed for increased susceptibility to cancer. In summary, the overall goal of this project is to elucidate the biological roles of Cdxl and Cdx2 in intestinal metaplasia and the molecular mechanisms of the transdifferentiation program induced by Cdxl and Cdx2.