Adam Emmanuelle, Quivy Vincent, Bex Françoise, Chariot Alain, Collette Yves, Vanhulle Caroline, Schoonbroodt Sonia, Goffin Véronique, Nguyên Thi Liên-Anh, Gloire Geoffrey, Carrard Géraldine, Friguet Bertrand, De Launoit Yvan, Burny Arsène, Bours Vincent, Piette Jacques, Van Lint Carine
Institut de Biologie et de Médecine Moléculaires, Service de Chimie Biologique, Laboratoire de Virologie Moléculaire, Université Libre de Bruxelles, 6041 Gosselies, Belgium.
Mol Cell Biol. 2003 Sep;23(17):6200-9. doi: 10.1128/MCB.23.17.6200-6209.2003.
Previous studies have implicated acetylases and deacetylases in regulating the transcriptional activity of NF-kappa B. Here, we show that inhibitors of deacetylases such as trichostatin A (TSA) and sodium butyrate (NaBut) potentiated TNF-induced expression of several natural NF-kappa B-driven promoters. This transcriptional synergism observed between TNF and TSA (or NaBut) required intact kappa B sites in all promoters tested and was biologically relevant as demonstrated by RNase protection on two instances of endogenous NF-kappa B-regulated gene transcription. Importantly, TSA prolonged both TNF-induced DNA-binding activity and the presence of NF-kappa B in the nucleus. We showed that the p65 subunit of NF-kappa B was acetylated in vivo. However, this acetylation was weak, suggesting that other mechanisms could be implicated in the potentiated binding and transactivation activities of NF-kappa B after TNF plus TSA versus TNF treatment. Western blot and immunofluorescence confocal microscopy experiments revealed a delay in the cytoplasmic reappearance of the I kappa B alpha inhibitor that correlated temporally with the prolonged intranuclear binding and presence of NF-kappa B. This delay was due neither to a defect in I kappa B alpha mRNA production nor to a nuclear retention of I kappa B alpha but was rather due to a persistent proteasome-mediated degradation of I kappa B alpha. A prolongation of I kappa B kinase activity could explain, at least partially, the delayed I kappa B alpha cytoplasmic reappearance observed in presence of TNF plus TSA.
以往的研究表明，乙酰化酶和去乙酰化酶参与调节核因子-κB（NF-κB）的转录活性。在此，我们发现去乙酰化酶抑制剂，如曲古抑菌素A（TSA）和丁酸钠（NaBut），可增强肿瘤坏死因子（TNF）诱导的多个天然NF-κB驱动启动子的表达。在TNF与TSA（或NaBut）之间观察到的这种转录协同作用，在所有测试的启动子中都需要完整的κB位点，并且具有生物学相关性，这通过对两例内源性NF-κB调节的基因转录进行核糖核酸酶保护得以证明。重要的是，TSA延长了TNF诱导的DNA结合活性以及NF-κB在细胞核中的存在时间。我们发现NF-κB的p65亚基在体内发生了乙酰化。然而，这种乙酰化作用较弱，这表明在TNF加TSA处理与TNF处理后，NF-κB结合和反式激活活性增强可能涉及其他机制。蛋白质印迹和免疫荧光共聚焦显微镜实验显示，IκBα抑制剂在细胞质中重新出现的时间延迟，这与NF-κB在细胞核内结合和存在时间的延长在时间上相关。这种延迟既不是由于IκBα mRNA产生缺陷，也不是由于IκBα在细胞核内滞留，而是由于蛋白酶体介导的IκBα持续降解。IκB激酶活性的延长至少可以部分解释在TNF加TSA存在的情况下观察到的IκBα细胞质重新出现延迟的现象。
