Bahouth S W, Park E A, Beauchamp M, Cui X, Malbon C C
Department of Pharmacology, College of Medicine, University of Tennessee Memphis 38163, USA.
Recept Signal Transduct. 1996;6(3-4):141-9.
The expression of the gene encoding the rat beta 1-adrenergic receptor is suppressed by glucocorticoids (Kiely et al., 1994). Within the 3.2-kb 5'-flanking region of the promoter, two potential glucocorticoid response elements (GREs) at -950 and -2791 relative to the translational ATG were identified. Characterization of the glucocorticoid-responsive sequences in the 5'-flanking region of the beta 1-adrenergic receptor gene was explored in rat C6 glioma cells and human HepG2 hepatoma cells using transient expression of beta 1-adrenergic receptor-luciferase fusion genes. The ability of glucocorticoids to suppress luciferase expression was not altered when the most 5'-localized GRE was deleted. Deleting the potential GRE at -950, in contrast, abolished glucocorticoid-induced suppression of the beta 1-adrenergic receptor-luciferase gene transcription. A 25-bp element containing the GRE sequence between nucleotides -950 and -926 confers glucocorticoid-dependent inhibition of transcription to a neutral promoter. Gel mobility shift assays with the alpha-subunit of the human glucocorticoid receptor (hGR alpha) expressed in reticulocyte lysates demonstrated specific binding to the 25-bp sequence harboring the putative GRE. We report an inhibitory GRE in the promoter of the rat beta 1-adrenergic receptor gene that is conserved among the rat, human, and mouse genes.
大鼠β1 - 肾上腺素能受体编码基因的表达受到糖皮质激素的抑制（基利等人，1994年）。在启动子的3.2 kb 5'侧翼区域内，相对于翻译起始密码子ATG，在 - 950和 - 2791处鉴定出两个潜在的糖皮质激素反应元件（GREs）。利用β1 - 肾上腺素能受体 - 荧光素酶融合基因的瞬时表达，在大鼠C6胶质瘤细胞和人HepG2肝癌细胞中探索了β1 - 肾上腺素能受体基因5'侧翼区域中糖皮质激素反应序列的特征。当最靠近5'端的GRE被删除时，糖皮质激素抑制荧光素酶表达的能力没有改变。相比之下，删除 - 950处的潜在GRE则消除了糖皮质激素诱导的β1 - 肾上腺素能受体 - 荧光素酶基因转录抑制。一个包含 - 950至 - 926核苷酸之间GRE序列的25 bp元件赋予了糖皮质激素依赖性转录抑制作用给一个中性启动子。用在网织红细胞裂解物中表达的人糖皮质激素受体（hGRα）的α亚基进行凝胶迁移率变动分析，结果表明其与含有假定GRE的25 bp序列有特异性结合。我们报道了大鼠β1 - 肾上腺素能受体基因启动子中的一个抑制性GRE，该GRE在大鼠、人和小鼠基因中是保守的。
