Spatiotemporal Regulation of Intestinal Gene Expression

描述（由申请方提供）：乳糖酶不持久性（成人型乳糖酶缺乏）导致消化系统乳糖吸收不良，乳糖是牛奶中存在的碳水化合物常量营养素。与肠道乳糖酶持久性和非持久性相关的人类DNA序列变异最近已被确定。本研究项目的重点是表征人类肠道乳糖酶持久性的遗传决定因素。我们以前的特点是调节大鼠乳糖酶基因在细胞培养和活动物中的精氨酸特异性表达的分子机制。我们现在将注意力集中在表征介导人类乳糖酶基因持久性和非持久性的分子机制，以及啮齿类动物乳糖酶的时间下降。初步研究表明，乳糖酶基因多态性区域的DNA序列可以结合核蛋白并增强乳糖酶启动子活性。我们推测，DNA多态性与乳糖酶持久性功能，以调节乳糖酶基因转录在成人肠上皮细胞通过不同的相互作用与特定的核蛋白转录因子。因此，研究目标旨在确定人类乳糖酶持久性的遗传决定因素的机械作用。在目标1中，我们将描述与人类乳糖酶基因转录持续性相关的DNA多态性的功能作用。将在细胞培养和转基因小鼠体内研究乳糖酶基因多态性的功能表征。在目标2中，我们将确定调节人乳糖酶持久性基因转录的分子机制。这个目标的目的将是确定和表征核蛋白能够相互作用的DNA序列的乳糖酶基因多态性与乳糖酶的持久性和表征是否核蛋白的功能，以调节乳糖酶的转录。在目标3中，为了补充我们对人类乳糖酶持续性机制的研究，我们将进一步阐明调节啮齿动物乳糖酶时间下降的机制。调节人乳糖酶基因表达的机制的知识可能会提供未来的新的诊断，治疗或预后的胃肠道疾病，导致上皮细胞消化功能的损失或不适当的增益策略。我们的体外和体内实验方法的结合将阐明与乳糖酶持久性和非持久性相关的遗传决定因素的作用。公共卫生相关性：成人型乳糖酶缺乏症，即乳糖酶不持久性，使世界上许多成年人对牛奶和其他乳制品的过度消费不耐受。然而，在一些成年人中，高水平的乳糖酶活性在成年期持续存在，这可能是由于遗传了阻止乳糖酶表达正常成熟下降的基因突变。了解消化乳糖酶基因表达的调控机制可能为增强肠道疾病中消化酶的表达提供新的策略，并将对了解其他基因与衰老的调控产生广泛的影响。

DESCRIPTION (provided by applicant): Lactase non-persistence (adult-type hypolactasia) results in digestive system malabsorption of lactose, the carbohydrate macronutrient present in milk. Human DNA sequence variants associated with intestinal lactase persistence and non-persistence have recently been identified. This research project focuses on characterization of the genetic determinants of intestinal lactase persistence in humans. We have previously characterized molecular mechanisms regulating intestine-specific expression of the rat lactase gene in cell culture and in living animals. We will now direct attention to characterization of the molecular mechanisms mediating human lactase gene persistence and non- persistence and the temporal decline of lactase in rodents. Preliminary studies have shown that DNA sequences in the region of lactase gene polymorphisms can bind nuclear proteins and enhance lactase promoter activity. We hypothesize that DNA polymorphisms associated with lactase persistence function to regulate lactase gene transcription in adult human enterocytes via differential interaction with specific nuclear protein transcription factors. Research objectives are therefore aimed at defining the mechanistic roles of genetic determinants of human lactase persistence. In Aim 1, we will characterize a functional role for DNA polymorphisms associated with persistence of lactase gene transcription in humans. Functional characterization of lactase gene polymorphisms will be investigated in cell culture and in vivo in transgenic mice. In Aim 2, we will define the molecular mechanisms regulating human lactase persistence gene transcription. The goals of this aim will be to identify and characterize nuclear proteins capable of interacting with DNA sequences in the region of lactase gene polymorphisms associated with lactase persistence and to characterize whether the nuclear proteins function to regulate lactase transcription. In Aim 3, to complement our investigation of the mechanism of lactase persistence in humans, we will further elucidate mechanisms regulating the temporal decline of lactase in rodents. Knowledge of mechanisms regulating human lactase gene expression may provide future novel diagnostic, therapeutic or prognostic strategies for gastrointestinal disorders that result in loss or inappropriate gain of epithelial cell digestive function. Our combination of in vitro and in vivo experimental approaches will elucidate roles for the genetic determinants associated with lactase persistence and non-persistence. PUBLIC HEALTH RELEVANCE: Adult-onset hypolactasia, lactase non-persistence, renders much of the world's adult human population intolerant of excessive consumption of milk and other dairy products. In some adults, however, high levels of lactase enzyme activity persist in adulthood presumably due to inheritance of a genetic mutation that prevents the normal maturational decline in lactase expression. Knowledge of mechanisms regulating expression of the digestive lactase gene may provide novel strategies for enhancing expression of digestive enzymes in intestinal diseases and will have broad implications for understanding regulation of other genes with aging.