SURGICAL STUDIES OF ONTOGENY, AGING AND THE GUT

肠道的分化和随后的发育代表了 重要的临床课题，但迄今为止，人们对它知之甚少。 基因组的开启或关闭是有序和同步的， 肠从未分化的内胚层演变为 它的成年分化形式;这些基因表达的变化是 主要由基因的激活或抑制介导 转录。我们之前的发现已经确定了晚期- 分化的神经降压素（NT）基因（命名为NT/N）作为一个优秀的 分子模型来描绘复杂的细胞机制， 导致分化区域特异性表达模式 专门的功能。我们已经证明，NT/N表达是 在不同的时间和空间上受到发育调控 特定模式; NT/N表达最初在胎儿中较低，但 在出生后迅速增加， 地形分布与增加NT/N表达沿着 小肠的纵轴。在人类结肠中，NT/N是 在胎儿中短暂表达，但在成人中被抑制; 然而，NT/N在某些结肠癌中重新表达。中央 我们的建议的假设仍然是，严格的表达 肠道中的NT/N模式受以下机制调节： 主要是转录调控。为了检验这个假设，我们有 具有以下具体目标的实验：（l）我们将进一步 明确NT/N发展模式的调控因素 在肠道中的表达。(2)我们将确定导致 在结肠癌中异位NT/N表达。(3)我们将描述 年龄相关的NT/N表达变化和NT介导的生长， 直觉(4)我们将在体内分析所需的NT/N调控元件 肠道中严格的表达模式。为了实现这一目标，我们 将开发具有人NT/N调节区的转基因品系 连接到报告基因，以确定所需的元件， 概括了NT/N表达的正常发育模式。的 我们研究的最终目标是确定分子机制 在体内调节NT/N表达。了解蛋白质-DNA 限制NT/N表达所需的相互作用将 产生重要的信息的监管和实现的 分化的肠道表型。此外，分析这些细胞 不仅能更好地理解正常的肠道 发展和功能，但也可以提供一个模型，以更好地 阐明导致肠道肿瘤形成的细胞事件。

Differentiation and subsequent development of the gut represents an important clinical topic but one that is, to date, poorly understood. Sets of genes are turned on or off in an ordered and synchronized pattern as the intestine evolves from an undifferentiated endoderm into its adult differentiated form; these changes in gene expression are mediated primarily by the activation or repression of gene transcription. Our previous findings have identified the terminally- differentiated neurotensin (NT) gene (designated NT/N) as an excellent molecular model to delineate the complex cellular mechanisms regulating the region-specific patterns of expression which lead to differentiation and specialized function. We have shown that NT/N expression is developmentally regulated in a distinctive temporal- and spatial- specific pattern; NT/N expression is initially low in the fetus but rapidly increases after birth to assume the distinctive adult topographical distribution with increasing NT/N expression along the longitudinal axis of the small bowel. In the human colon, NT/N is transiently expressed in the fetus but is repressed in the adult; however, NT/N is reexpressed in certain colon cancers. The central hypothesis of our proposal continues to be that the strict expression pattern of NT/N in the gut is regulated by mechanisms which involve mainly transcriptional regulation. To examine this hypothesis we have panned experiments with the following SPECIFIC AIMS: (l) We will further define the factors regulating the developmental pattern of NT/N expression in the gut. (2) We will determine the mechanisms leading to ectopic NT/N expression in colon cancers. (3) We will characterize the age-related alterations of NT/N expression and NT-mediated growth in the gut. (4) We will analyze in vivo the NT/N regulatory elements required for the strict expression pattern in the gut. To achieve this goal, we will develop transgenic lines with the human NT/N regulatory region linked to a reporter gene to determine the elements that are required to recapitulate the normal developmental pattern of NT/N expression. The ultimate goal of our studies is to define the molecular mechanisms regulating NT/N expression in vivo. Understanding the protein-DNA interactions that are required for restricting NT/N expression will yield important information on the regulation and attainment of the differentiated gut phenotype. In addition, analysis of these cellular processes will provide a better understanding of not only normal gut development and function but may also provide a model to better elucidate the cellular events leading to gut neoplasia.