Villarete L H, Remick D G
Department of Pathology, University of Michigan Medical School, Ann Arbor, USA.
Am J Pathol. 1996 Nov;149(5):1685-93.
Steady-state mRNA for interleukin (IL) 8 persists significantly longer than mRNA for tumor necrosis factor (TNF)-alpha in lipopolysaccharide (LPS) stimulated human whole blood. Nuclear run-ons demonstrated consistent levels of transcriptional activity of the IL-8 gene at 2 and 26 hours after LPS stimulation when compared with the rapid induction and arrest of the TNF-alpha gene. Inhibition of cellular transcription with actinomycin D added at 2 hours after LPS resulted in the substantial decrease of both IL-8 and TNF-alpha mRNAs, demonstrating half-lives of 4.6 and 2.3 hours, respectively. In contrast, inhibition of transcription at 23 hours after LPS revealed extremely stable IL-8 mRNA with a half-life of > 10 hours. The half-life of beta-actin in the same actinomycin-D-treated samples did not vary significantly from the half-life calculated at the 2-hour time point (5.5 hours versus 5.6 hours), indicating that the observed IL-8 mRNA stability was not an artifact of the system. Both IL-8 and TNF-alpha protein levels decreased when actinomycin D was added 2 hours after LPS stimulation. However, no effect in IL-8 protein levels was evident when actinomycin D was added at 23 hours after LPS. These results demonstrate that IL-8 mRNA stability is controlled at both the transcriptional and posttranscriptional levels of gene regulation.
在脂多糖（LPS）刺激的人全血中，白细胞介素（IL）-8的稳态mRNA持续时间比肿瘤坏死因子（TNF）-α的mRNA长得多。核转录实验表明，与TNF-α基因的快速诱导和停止相比，LPS刺激后2小时和26小时，IL-8基因的转录活性水平保持一致。在LPS刺激后2小时添加放线菌素D抑制细胞转录，导致IL-8和TNF-α mRNA均大幅下降，表明它们的半衰期分别为4.6小时和2.3小时。相比之下，在LPS刺激后23小时抑制转录，显示IL-8 mRNA极其稳定，半衰期大于10小时。在相同的放线菌素D处理样本中，β-肌动蛋白的半衰期与在2小时时间点计算的半衰期相比没有显著差异（5.5小时对5.6小时），这表明观察到的IL-8 mRNA稳定性不是该系统的假象。当在LPS刺激后2小时添加放线菌素D时，IL-8和TNF-α蛋白水平均下降。然而，在LPS刺激后23小时添加放线菌素D时，IL-8蛋白水平没有明显变化。这些结果表明，IL-8 mRNA稳定性在基因调控的转录和转录后水平均受到控制。
