Kelly E J, Sandgren E P, Brinster R L, Palmiter R D
Department of Biochemistry, Howard Hughes Medical Institute, University of Washington, Box 357370, Seattle, WA 98195, USA.
Proc Natl Acad Sci U S A. 1997 Sep 16;94(19):10045-50. doi: 10.1073/pnas.94.19.10045.
Synthesis of mouse metallothionein (MT)-I and MT-II is transcriptionally induced by the synthetic glucocorticoid, dexamethasone (DEX) or both in vivo as well as in numerous cell lines. However, the location(s) of a glucocorticoid response element (GRE) has not been described. The observation that a marked MT-I gene, as well as heterologous genes, when placed in the context of 17 kb of flanking sequence from the MT locus, are inducible by DEX and lipopolysaccharide in transgenic mice renewed the search for the GRE. Analysis of a series of deletion constructs from this 17-kb region in cultured cells identified a single 455-bp region that conferred DEX induction on a reporter gene. This 455-bp region contains two GREs that bind to the glucocorticoid receptor as assessed by gel mobility shift. Deletion of this fragment from the 17-kb flanking region eliminates the DEX responsiveness of reporter genes. The two GREs, which are located approximately 1 kb upstream of the MT-II gene and approximately 7 kb upstream of the MT-I gene, are necessary for induction of both genes and can function independently of elements within the proximal promoter region of either gene.
合成糖皮质激素地塞米松（DEX）在体内以及众多细胞系中均可转录诱导小鼠金属硫蛋白（MT）-I和MT-II的合成。然而，糖皮质激素反应元件（GRE）的位置尚未明确。当将一个显著的MT-I基因以及异源基因置于来自MT基因座的17 kb侧翼序列的背景下时，在转基因小鼠中可被DEX和脂多糖诱导，这一观察结果重新引发了对GRE的寻找。对培养细胞中该17 kb区域的一系列缺失构建体进行分析，确定了一个455 bp的单一区域，该区域可赋予报告基因DEX诱导作用。通过凝胶迁移率变动分析评估，这个455 bp区域包含两个与糖皮质激素受体结合的GRE。从17 kb侧翼区域删除该片段会消除报告基因的DEX反应性。这两个GRE分别位于MT-II基因上游约1 kb处和MT-I基因上游约7 kb处，是诱导这两个基因所必需的，并且其功能独立于任一基因近端启动子区域内的元件。
