大鼠丝氨酸脱水酶基因中多个糖皮质激素反应元件的定位与特性分析

Location and characterization of multiple glucocorticoid-responsive elements in the rat serine dehydratase gene.

作者信息

Su Y, Pitot H C

机构信息

McArdle Laboratory for Cancer Research, Department of Oncology, Medical School, University of Wisconsin, Madison 53706.

出版信息

Arch Biochem Biophys. 1992 Sep;297(2):239-43. doi: 10.1016/0003-9861(92)90667-l.

DOI:10.1016/0003-9861(92)90667-l

PMID:1497343

Abstract

Transcription of the gene coding for serine dehydratase (SDH, EC 4.2.1.13) in the rat in vivo is dramatically increased by glucocorticoid hormones. To identify DNA elements mediating the glucocorticoid-regulated expression of the SDH gene, we transiently transfected 7AD-7 rat hepatoma cells with fusion genes consisting of various regions of the SDH 5' flanking sequence linked to the coding sequence of the gene for chloramphenicol acetyltransferase (CAT). Analysis of the CAT activities from these 5' deletion mutants identified three closely associated glucocorticoid-responsive elements (GREs), located more than 5 kb upstream relative to the cap site. Two distal GREs act synergistically to confer strong glucocorticoid inducibility to the gene, whereas the proximal GRE functions independently of the distal GREs and confers only a weak hormone response to the gene. The purified DNA-binding domain of rat glucocorticoid receptor binds to the sequence of each GRE as shown by footprinting experiments. However, only one of these sequences contains the TGTTCT consensus sequence reportedly associated with many other GREs.

摘要

在大鼠体内，丝氨酸脱水酶（SDH，EC 4.2.1.13）编码基因的转录会因糖皮质激素而显著增加。为了鉴定介导糖皮质激素调节SDH基因表达的DNA元件，我们用融合基因瞬时转染了7AD - 7大鼠肝癌细胞，这些融合基因由SDH 5'侧翼序列的不同区域与氯霉素乙酰转移酶（CAT）基因的编码序列相连组成。对这些5'缺失突变体的CAT活性分析确定了三个紧密相连的糖皮质激素反应元件（GREs），它们相对于帽位点位于上游超过5 kb处。两个远端GRE协同作用，赋予该基因强大的糖皮质激素诱导性，而近端GRE独立于远端GRE起作用，仅赋予该基因微弱的激素反应。足迹实验表明，大鼠糖皮质激素受体的纯化DNA结合结构域与每个GRE的序列结合。然而，这些序列中只有一个包含据报道与许多其他GRE相关的TGTTCT共有序列。