Rosewicz S, McDonald A R, Maddux B A, Goldfine I D, Miesfeld R L, Logsdon C D
Cell Biology Laboratory, Mount Zion Hospital and Medical Center, San Francisco, California 94120.
J Biol Chem. 1988 Feb 25;263(6):2581-4.
The effect of glucocorticoids on the regulation of glucocorticoid receptor mRNA was studied in two different cell lines, human IM-9 lymphocytes and rat pancreatic acinar AR42J cells. Using a glucocorticoid receptor cDNA probe, glucocorticoid receptor mRNA was examined by Northern blot hybridization and quantitated by slot-blot hybridization. In IM-9 and AR42J cells, dexamethasone decreased steady-state glucocorticoid receptor mRNA levels to approximately 50% of control. This decrease occurred with a one-half time of 3 h for IM-9 cells and 6 h for AR42J cells. Dexamethasone was the most potent steroid tested with a one-half maximal effect occurring at 10 nM and a maximal effect occurring at 100 nM. Glucocorticoid receptor mRNA half-life and gene transcription were then studied to determine the mechanism of decreased mRNA levels. The glucocorticoid mRNA half-life was approximately 120 min in IM-9 cells and 240 min in AR42J cells; these rates were not affected by dexamethasone treatment. In contrast, the rate of glucocorticoid gene transcription as measured by run-on assays in IM-9 cells was decreased to 50 +/- 6% of control by dexamethasone. These results indicate therefore that glucocorticoids regulate glucocorticoid receptor mRNA levels by influencing gene transcription.
在两种不同的细胞系，即人IM-9淋巴细胞和大鼠胰腺腺泡AR42J细胞中，研究了糖皮质激素对糖皮质激素受体mRNA调节的影响。使用糖皮质激素受体cDNA探针，通过Northern印迹杂交检测糖皮质激素受体mRNA，并通过狭缝印迹杂交进行定量。在IM-9和AR42J细胞中，地塞米松使糖皮质激素受体mRNA的稳态水平降至对照的约50%。这种下降在IM-9细胞中的半衰期为3小时而在AR42J细胞中为6小时。地塞米松是所测试的最有效的类固醇，其最大效应的一半出现在10 nM，最大效应出现在100 nM。随后研究了糖皮质激素受体mRNA的半衰期和基因转录，以确定mRNA水平降低的机制。糖皮质激素mRNA在IM-9细胞中的半衰期约为120分钟，在AR42J细胞中为240分钟；这些速率不受地塞米松处理的影响。相反，通过IM-9细胞中的连续分析测量的糖皮质激素基因转录速率被地塞米松降低至对照的50±6%。因此，这些结果表明糖皮质激素通过影响基因转录来调节糖皮质激素受体mRNA水平。
