Regulation of Intestinal Nutrient Transporters

描述：（由申请人提供）钠/葡萄糖协同转运蛋白（SGLT 1） 主要由小肠细胞表达， 单糖，葡萄糖和半乳糖，穿过顶膜。为 SGLT 1是管腔葡萄糖和半乳糖的唯一转运蛋白，其功能是 对于充分吸收富含乳制品和其他食品的饮食至关重要 加工糖SGLT 1基因的遗传突变导致 常染色体隐性遗传疾病，葡萄糖/半乳糖吸收不良，通常 出生后不久出现严重的危及生命的吸收不良。在 人类SGLT 1的表达，主要在 转录，以昼夜模式变化。调查人员仔细地 解剖SGLT 1基因的启动子近端元件，并确定 SP1和HNF-1在驱动罗勒表达中起着关键作用， 细胞系然而，仅凭这一地区还不足以建立 在肠中报告的荧光素酶的一致表达， 转基因小鼠品系这些数据被解释为， 必须存在远端调控元件，以驱动精氨酸特异性的 SGLT 1的表达。为了开始确定关键的基因控制区域， SGLT 1基因，研究者已经克隆了40 kb的5-上游区域， 它的整个核苷酸序列已经确定。他现在打算测试 SGLT 1基因的表达受一个远端的 调节位点这将通过实现两个具体目标来实现。第一 是为了确定组织特异性DNase 1超敏位点， SGLT 1基因周围的区域。二是在体内和体内同时使用 体外模型，以评估DNA元件的潜在作用， DNA酶1超敏反应试验，以控制SGLT 1表达。监管 SGLT 1基因的控制区必须包含各种核蛋白 调控元件以独特的方式控制其转录调控， 组织和时间表达模式。确定和进一步 这些顺式元件的表征将提供对 肠细胞特异性细胞命运的分子机制和各种因素 调解其规则。

DESCRIPTION: (provided by applicant) The sodium/glucose cotransporter (SGLT1) is expressed primarily by small intestinal cells and transports the monosaccharides, glucose and galactose, across the apical membrane. As the exclusive transporter of luminal glucose and galactose, SGLT1's function is essential for adequate assimilation of a diet rich in dairy products and other processed sugars. Inherited mutations of the SGLT1 gene result in the autosomal recessive disorder, glucose/galactose malabsorption, that typically presents shortly after birth with severe life-threatening malabsorption. In humans expression of SGLT1, which is controlled primarily at the level of transcription, varies in a diurnal pattern. The investigator has carefully dissected the promoter-proximal element of the SGLT1 gene and determined the critical role that SP1 and HNF-1 play in driving basil expression in various cell lines. However, this region alone is not sufficient to establish consistent expression of the luciferase reported in the intestine of transgenic mouse lines. These data were interpreted to suggest that other distal regulatory elements must exist in order to drive intestine-specific expression of SGLT1. To begin identifying the critical locus control region of the SGLT1 gene, the investigator has cloned 40 kb of the 5-upstream region and its entire nucleotide sequence has been determined. He now proposes to test the hypothesis that expression of SGLT1 gene is controlled by a distal regulatory locus. This will be done by achieving two specific aims. The first is to identify the tissue-specific DNase1 hypersensitivity sites in the regions surrounding the SGLT1 gene. The second is to use both in vivo and in vitro models to assess the potential role of the DNA elements identified by DNase1 hypersensitivity assays to control SGLT1 expression. The regulatory control regions of the SGLT1 gene must contain various nuclear protein regulatory elements that control its transcriptional regulation in a unique tissue and temporal pattern of expression. The identification and further characterization of these cis elements will provide better insight into the molecular mechanism of enterocyte-specific cell fate and the various factors mediating its regulation.