Chandler V L, Maler B A, Yamamoto K R
Cell. 1983 Jun;33(2):489-99. doi: 10.1016/0092-8674(83)90430-0.
Glucocorticoids stimulate transcriptional initiation within integrated mammary tumor virus (MTV) DNA sequences in infected cells. We report here that production of herpes simplex virus thymidine kinase (tk) RNA is stimulated as much as 50-fold by the glucocorticoid, dexamethasone, when sequences from a particular region of MTV DNA are fused upstream of the normally constitutive tk promoter region. Three cloned fragments of MTV DNA were tested, each itself lacking the sequences required for transcription initiation. We monitored the effects of dexamethasone on the efficiency with which these recombinants transfect a tk- rat cell line to a tk+ phenotype, and measured tk enzymatic activity, the size and abundance of tk mRNA, and the 5' termini of tk transcripts in the transfectants. We conclude that the MTV promoter region contains a "glucocorticoid response element" that can be separated from a second element essential for MTV transcription initiation. The hormone response element maps within a 340-base pair MTV DNA fragment that contains specific binding sites for purified glucocorticoid receptor protein in vitro, implying that receptor binding at these sites in vivo may mediate hormone responsiveness. Comparison of several different constructions indicates that the location and orientation of the glucocorticoid response element relative to the transcription start site is not rigidly constrained.
糖皮质激素可刺激受感染细胞中整合的乳腺肿瘤病毒（MTV）DNA序列内的转录起始。我们在此报告，当将MTV DNA特定区域的序列融合到正常组成型胸苷激酶（tk）启动子区域的上游时，单纯疱疹病毒胸苷激酶（tk）RNA的产生会被糖皮质激素地塞米松刺激多达50倍。测试了MTV DNA的三个克隆片段，每个片段本身都缺乏转录起始所需的序列。我们监测了地塞米松对这些重组体将tk -大鼠细胞系转染为tk +表型的效率的影响，并测量了转染子中的tk酶活性、tk mRNA的大小和丰度以及tk转录本的5'末端。我们得出结论，MTV启动子区域包含一个“糖皮质激素反应元件”，该元件可以与MTV转录起始所必需的第二个元件分开。激素反应元件位于一个340碱基对的MTV DNA片段内，该片段在体外含有纯化的糖皮质激素受体蛋白的特异性结合位点，这意味着体内这些位点的受体结合可能介导激素反应性。几种不同构建体的比较表明，糖皮质激素反应元件相对于转录起始位点的位置和方向并非严格受限。
