Cdx in GI Differentiation and Transdifferentiation

GI 分化和转分化中的 Cdx

• 批准号: 6322225
• 负责人: DEBRA G. SILBERG
• 金额: $ 28.53万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6322225
• 关键词: cell differentiation; developmental genetics; embryogenesis; gastric mucosa; gastrointestinal system; genetic regulatory element; genetically modified animals; goblet cells; histogenesis; homeobox genes; laboratory mouse; metaplasia; oral mucosa; preneoplastic state; subtraction hybridization; transcription factor

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.

描述（申请人的摘要）：多个基因的复杂相互作用 在内胚层和中胚层中表达是分化所必需的 胃肠道的发育。专业化、特色鲜明 食道、胃、肠和结肠的上皮由 胚胎发生过程中的内胚层。这些器官的独特特征是 通常维持终生，然而，转分化或肠 化生可能发生在食管或食管中出现肠型粘膜的情况下 胃。这种重要的人类癌前病变的起源尚不清楚，但 具有明确的临床相关性。 CDX1 和 CDX2，肠道特异性同源盒 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 表达于胃和食管粘膜的肠化生中。这 研究人员假设 CDX1 和 CDX2 指导转分化 发生在肠化生中的程序。这个假设将得到解决 通过相互关联的具体目标，利用转基因小鼠模型来探索 Cdxl 和 Cdx2 对发育中的胃和成人胃的影响 通过这两个基因的错误表达来影响食管上皮细胞。具体目标1 检查早期胚胎发生中 Cdx 表达的生物学后果。 Cdxl和Cdx2的编码区将置于 Hnf3gamma 顺式调节元件，将指导 Cdxl 的异位表达 或转基因小鼠发育中胃的内胚层中的Cdx2。这 申请人已通过该方法成功表达了Cdx2，并已 肠型细胞的证据。具体目标2利用第二个转基因 小鼠模型来定义 Cdx 表达对分化的影响 通过放置Cdxl或Cdx2的编码区来食管和胃粘膜 在四环素诱导型启动子的控制下。两者的表型 将检查转基因模型的形态和基因变化 表达。将确定肠道特定基因的表达并 后续分析将包括消减杂交以进行详细研究 在表达转基因的组织中差异表达的基因。在 此外，由于肠化生是人类的一种癌前病变， 将评估动物对癌症的易感性是否增加。总之， 该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。