Nonstructural proteins 4A and 4B of hepatitis C virus transactivate the interleukin 8 promoter
Nonstructural proteins 4A and 4B of hepatitis C virus transactivate the interleukin 8 promoter
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DOI：
10.1111/j.1348-0421.2005.tb03728.x
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发表时间：
2005-01-01
影响因子：
2.6
通讯作者：
Hotta, H
中科院分区：
文献类型：
--
作者：
Kadoya, H;Nagano-Fujii, M;Hotta, H
白介素8(IL-8)在包括病毒感染在内的多种刺激下在多种细胞类型中被诱导。据报道，丙型肝炎病毒非结构蛋白5A(NS5A)在mRNA和蛋白水平均参与诱导培养的人细胞表达IL-8。在这项研究中，我们旨在通过IL-8启动子驱动的荧光素酶报告基因分析和内源性IL-8mRNA和分泌IL-8蛋白水平的测定，来确定另一种丙型肝炎病毒蛋白(S)是否反式激活IL-8基因的表达。我们观察到，NS4B和NS4A在较小程度上显著反式激活了IL-8启动子，导致IL-8蛋白的产生增加。此外，与对照细胞相比，携带丙型肝炎病毒亚基因组RNA复制子的Huh-7细胞中IL-8的表达增强。IL-8启动子的缺失突变分析表明，转录因子AP-1可能参与了NS4A和NS4B介导的IL-8基因激活。此外，NS4B而不是NS4A对IL-8基因的激活可能涉及到核因子-kappaB和/或NFIL-6。NS4B和NS4A的反式激活程度在不同的人类细胞系中有所不同，其中HeLa细胞表现出最强的激活，其次是Huh-7细胞，而HepG2细胞表现出微弱的激活水平。综上所述，我们的结果提示NS4B和NS4A在某些细胞条件下在诱导IL-8基因表达方面发挥重要作用，这可能是建立持续性丙型肝炎病毒感染的策略之一。
Interleukin 8 (IL-8) is induced in many cell types by various stimuli including virus infection. It was reported that nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) was involved in induction of IL-8 expression at both mRNA and protein levels in cultured human cells. In this study, we aimed to determine whether or not another HCV protein(s) transactivates the IL-8 gene expression, by means of an IL-8 promoter-driven luciferase reporter assay and measurement of endogenous IL-8 mRNA and secreted IL-8 protein levels. We observed that NS4B, and NS4A to a lesser extent, significantly transactivated the IL-8 promoter, which resulted in enhanced production of IL-8 protein. Also, the IL-8 expression was augmented in Huh-7 cells harboring an HCV subgenomic RNA replicon, compared with the control cells. Deletion mutational analysis of the IL-8 promoter revealed the possible involvement of the transcription factor AP-1 in both NS4A- and NS4B-mediated IL-8 gene activation. In addition, the IL-8 gene activation by NS4B, but not that by NS4A, was likely to involve NF-kappa B and/or NFIL-6. The degree of the transactivation by NS4B and NS4A varied with different human cell lines, with HeLa cells showing the strongest activation followed by Huh-7 cells, and with HepG2 cells exhibiting a marginal level of activation. Taken together, our present results suggest the possibility that NS4B and NS4A play an important role in inducing the IL-8 gene expression under certain cellular conditions, which might be one of the strategies to establish persistent HCV infection.