DEVELOPMENTAL REGULATION OF LACTASE GENE TRANSCRIPTION

描述(摘自申请人的摘要) 这项建议的主要目标是促进 在分子和生物科学领域的独立和富有成效的研究者 胃肠道发育生物学。长期的研究 这项建议的目的是要了解调控的分子机制 肠道乳糖酶基因转录的成熟性下降。 肠道乳糖酶是肠细胞二糖酶，负责 消化乳糖，牛奶中的主要碳水化合物。乳糖酶活性为 最大值在断奶前，然后在成熟期显著下降。 乳糖酶活性降低与过量饮用牛奶的结果 在大多数成熟哺乳动物的碳水化合物吸收不良症状中，包括 人类。调节这种成熟性衰退的机制 肠道乳糖酶活性尚未完全确定。 最近的报告表明，控制乳糖酶的下降主要是 在基因转录水平上。另外，我们的初步数据 提示乳糖酶启动子顺式元件在 肠道成熟至少由两种不同的核蛋白组成。我们的 基于这一数据的假设是，乳糖酶的成熟下降 表达是由其启动子和启动子之间的差异相互作用所介导的 特定的核转录因子。具体的研究目标， 因此，都是针对乳糖酶基因调控元件的表征 以及鉴定与这些元素相互作用的核蛋白。我们 目的通过分析确定乳糖酶DNA调控元件的特性。 表达与报告基因连锁的基因组缺失 转基因小鼠。我们将鉴定与乳糖酶相互作用的核蛋白 使用DNase I超敏、足迹和凝胶移位的基因片段 化验。我们的目标是通过改变它们的蛋白质的功能来表征它们 在细胞培养和转基因小鼠中的表达及检测 转录活性。 候选人在勾勒出研究调查的一个领域后，将进行 在一位导师的建议和指导下进行的研究 发育生物学。研究经验，辅以 分子和发育领域的课程和研讨会 生物学，将为候选人提供过渡到 作为一名独立而富有成效的科学家从事关于 肠道发育的分子生物学。

DESCRIPTION (Taken from the applicant's Abstract) The broad objective of this proposal is to foster the development of an independent and productive investigator in the area of molecular and developmental biology of the gastrointestinal tract. The long term research goal of this proposal is to understand the molecular mechanisms regulating the maturational decline in intestinal lactase gene transcription. Intestinal lactase is the enterocyte disaccharidase responsible for digestion of lactose, the primary carbohydrate in milk. Lactase activity is maximal prior to weaning and then declines significantly during maturation. Decreased lactase activity combined with excessive milk consumption results in symptoms of carbohydrate malabsorption in most mature mammals, including humans. The mechanisms involved in regulating this maturational decline in intestinal lactase activity have not been fully defined. Recent reports suggest that control of the decline in lactase is primarily at the level of gene transcription. In addition, our preliminary data suggest that a lactase promoter cis element is bound differentially during intestinal maturation by at least two distinct nuclear proteins. Our hypothesis, based on this data, is that the maturational decline in lactase expression is mediated by differential interaction between its promoter and specific nuclear transcription factors. Specific research objectives, therefore, are aimed at characterization of lactase gene regulatory elements and identification of nuclear proteins interacting with those elements. We aim to characterize the lactase DNA regulatory elements by analyzing expression of genomic deletions linked to a reporter gene and expressed in transgenic mice. We will identify nuclear proteins interacting with lactase gene fragments using DNase I hypersensitivity, footprint, and gel shift assays. We aim to functionally characterize the proteins by altering their expression in cell culture and in transgenic mice and assaying for transcriptional activity. The candidate, having delineated an area of research inquiry, will conduct the research with the advice and guidance of a mentor in the field of developmental biology. The research experience, supplemented with coursework and seminars in the fields of molecular and developmental biology, will provide the candidate with the tools needed to transition to a career as an independent and productive scientist performing research on the molecular biology of intestinal development.