Ree A H, Taskén K, Hansson V
Institute of Medical Biochemistry, University of Oslo, Norway.
J Steroid Biochem Mol Biol. 1994 Jan;48(1):23-9. doi: 10.1016/0960-0760(94)90247-x.
Treatment of MCF-7 cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (10(-7) M) was associated with a time-dependent increase in specific binding of [3H]dexamethasone (34.8 +/- 4.6 fmol/mg protein after 9 h of TPA treatment compared with 16.0 +/- 2.3 fmol/mg protein in control cells) as well as a transient induction in the level of glucocorticoid receptor (GR) mRNA (4- to 8-fold stimulation after 2-3 h, followed by a decline towards the control value after 6 h). In the presence of the transcription inhibitor actinomycin D (AMD) (5.0 micrograms/ml) the TPA-dependent induction of GR mRNA was completely abolished, and GR mRNA showed a gradual decline with a half-life of 2-3 h. In contrast, treatment with TPA and the protein synthesis inhibitor cycloheximide (50 microM) resulted in a superinduction of GR mRNA (> 50-fold after 6 h). Inhibition of a half-life of 2-3 h, which is identical to that observed in non-treated cells. We conclude that the increase in GR mRNA in the presence of TPA is dependent on ongoing transcription, whereas the rate by which GR transcripts are degraded, is not altered by TPA.
用佛波酯12 - O -十四烷酰佛波醇- 13 -乙酸酯（TPA）（10⁻⁷M）处理MCF - 7细胞，会导致[³H]地塞米松的特异性结合随时间增加（TPA处理9小时后为34.8±4.6 fmol/mg蛋白，而对照细胞为16.0±2.3 fmol/mg蛋白），同时糖皮质激素受体（GR）mRNA水平会有短暂诱导（2 - 3小时后刺激4至8倍，6小时后降至对照值）。在转录抑制剂放线菌素D（AMD）（5.0微克/毫升）存在的情况下，TPA依赖的GR mRNA诱导完全被消除，并且GR mRNA以2 - 3小时的半衰期逐渐下降。相反，用TPA和蛋白质合成抑制剂环己酰亚胺（50微摩尔）处理导致GR mRNA超诱导（6小时后>50倍）。半衰期为2 - 3小时的抑制作用，这与未处理细胞中观察到的相同。我们得出结论，在TPA存在下GR mRNA的增加依赖于正在进行的转录，而GR转录本的降解速率不受TPA影响。
