HOMEODOMAIN GENES IN INTESTINAL DEVELOPMENT

描述（改编自申请人的摘要）： 哺乳动物的肠道是由一个简单的 胚胎内胚层通过复杂的形态变化过程 和基因表达。 然而，人们对这种分子结构知之甚少。 指导和整合发展转型的机制 导致成熟的肠上皮结构。 使用表达克隆，申请人已经鉴定了编码 一种与转录有高亲和力结合并激活转录的蛋白 一种特异性的DNA调控元件。 编码的蛋白质 通过该cDNA是尾相关同源结构域家族的成员， 转录因子（Cdx）：同源结构域蛋白是核心重要性 在许多生物体的整个胚胎发生的发育过程中， 和器官形成。 该提议基于Cdx 基因对于指导细胞的发育和分化是重要的。 小鼠肠上皮细胞 因此，这一总体目标 应用是研究Cdx基因在肠道中的作用， 器官发生和分化。 为了实现这一目标，第一个目标 是克隆Cdx家族的同源结构域基因的成员， 在肠道发育过程中表达，并表征其 表达的时间和细胞模式。 克隆人将会 通过使用RNA的cDNA末端快速扩增（RACE）程序实现 从小肠和结肠的发育中， 用原位杂交技术在发育中的肠道中检测 和免疫组化。第二个目的是检查功能 Cdx基因在肠上皮分化中的作用 肠细胞系 几种细胞系来源于 肠组织或结肠癌，如功能的获得和丧失 Cdx基因的功能。 第三个目的是检查功能 Cdx基因在消化道发育中的作用 小鼠 将进行功能获得和功能丧失研究 在使用绒毛蛋白基因的启动子表达的转基因小鼠中， 含有Cdx基因编码区的构建体及其对Cdx基因的影响 将对发展进行评估。 该战略将允许评估 Cdx基因的过早和异位表达在 完整小鼠。

DESCRIPTION (Adapted from Applicants' Abstract): The epithelial lining of the mammalian intestinal tract develops from a simple tube of embryonic endoderm through a complex process of changes in morphology and gene expression. However, little is known about the molecular mechanisms that direct and integrate the developmental transitions leading to the mature configuration of the adult intestinal epithelium. Using expression cloning, the applicant has identified a cDNA encoding a protein that binds with high affinity to, and activates transcription of, an intestine-specific DNA regulatory element. The protein encoded by this cDNA is a member of the caudal-related homeodomain family of transcription factors (Cdx): homeodomain proteins are central importance in may organisms for developmental processes throughout embryogenesis and organogenesis. This proposal is based on the hypothesis that Cdx genes are important for directing development and differentiation of the mouse intestinal epithelim. Therefore, the overall goal of this application is to investigate the role of Cdx genes in intestinal organogenesis and differentiation. To achieve this goal, the first aim is to clone members of the Cdx family of homeodomain genes that are expressed during intestinal developmental and to characterize their temporal and cellular patterns of expression. The clonings will be achieved by Rapid Amplification of cDNA Ends (RACE) procedure using RNA from developing small intestine and colon and the patterns of expression examined in the developing intestinal tract using in situ hybridization and immunohistochemistry.The second aim is to examine the functional role of Cdx genes in differentiation of the intestinal epithelium using intestinal cell lines. Several cell lines that have been derived from intestinal tissue or colon carcinomas, as the gain of function and loss of function of Cdx genes. The third aim is to examine the functional role of Cdx genes ind development of digestive tract using the transgenic mice. Gain of function and loss of function studies will be performed in transgenic mice using the promoter of the villin gene to express constructs that contain coding regions for Cdx genes and the effect on development will be evaluated. The strategy will allow an assessment of the effect of premature and ectopic expression of Cdx genes in the intact mouse.