Potentiation of tumor necrosis factor-induced NF-κB activation by deacetylase inhibitors is associated with a delayed cytoplasmic reappearance of IκBα
Potentiation of tumor necrosis factor-induced NF-κB activation by deacetylase inhibitors is associated with a delayed cytoplasmic reappearance of IκBα
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DOI：
10.1128/mcb.23.17.6200-6209.2003
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发表时间：
2003-09-01
影响因子：
5.3
通讯作者：
Van Lint, CV
中科院分区：
文献类型：
--
作者：
Adam, E;Quivy, V;Van Lint, CV
先前的研究表明乙酰化酶和去乙酰化酶在调节核因子 - κB（NF - κB）的转录活性中起作用。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）诱导的几种天然的由NF - κB驱动的启动子的表达。在TNF和TSA（或NaBut）之间观察到的这种转录协同作用需要在所有测试的启动子中κB位点完整，并且如通过对两种内源性NF - κB调节的基因转录进行核糖核酸酶保护所证明的那样具有生物学相关性。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亚基在体内被乙酰化。然而，这种乙酰化作用较弱，这表明在TNF加TSA与TNF处理后，NF - κB的增强结合和反式激活活性可能涉及其他机制。蛋白质印迹和免疫荧光共聚焦显微镜实验显示，IκBα抑制剂在细胞质中的重新出现延迟，这在时间上与NF - κB在细胞核内结合时间延长和存在相关。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，而是由于蛋白酶体持续介导的IκBα降解。IκB激酶活性的延长至少可以部分解释在TNF加TSA存在时观察到的IκBα在细胞质中重新出现延迟的现象。
Previous studies have implicated acetylases and deacetylases in regulating the transcriptional activity of NF-kappaB. Here, we show that inhibitors of deacetylases such as trichostatin A (TSA) and sodium butyrate (NaBut) potentiated TNF-induced expression of several natural NF-kappaB-driven promoters. This transcriptional synergism observed between TNF and TSA (or NaBut) required intact kappaB sites in all promoters tested and was biologically relevant as demonstrated by RNase protection on two instances of endogenous NF-kappaB-regulated gene transcription. Importantly, TSA prolonged both TNF-induced DNA-binding activity and the presence of NF-kappaKB in the nucleus. We showed that the p65 subunit of NF-kappaB 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-kappaB after TNF plus TSA versus TNF treatment. Western blot and immunofluorescence confocal microscopy experiments revealed a delay in the cytoplasmic reappearance of the IkappaBalpha inhibitor that correlated temporally with the prolonged intranuclear binding and presence of NF-kappaB. This delay was due neither to a defect in IkappaBalpha mRNA production nor to a nuclear retention of IkappaBalpha but was rather due to a persistent proteasome-mediated degradation of IkappaBalpha. A prolongation of IkappaB kinase activity could explain, at least partially, the delayed IkappaBalpha cytoplasmic reappearance observed in presence of TNF plus TSA.