Prinarakis Efthimios, Chantzoura Eleni, Thanos Dimitris, Spyrou Giannis
Center of Basic Research I-Biochemistry Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece.
EMBO J. 2008 Mar 19;27(6):865-75. doi: 10.1038/emboj.2008.28. Epub 2008 Feb 28.
Interferon regulatory factor 3 (IRF3) is an essential transcriptional regulator of the interferon genes. IRF3 is constitutively present in a latent conformation in the cell cytoplasm. In cells infected by Sendai virus, IRF3 becomes phosphorylated, homodimerizes, translocates to the nucleus, binds to target genes and activates transcription by interacting with CBP/p300 co-activators. In this study, we report that in non-infected cells IRF3 is post-translationally modified by S-glutathionylation. Upon viral-infection, it undergoes a deglutathionylation step that is controlled by the cytoplasmic enzyme glutaredoxin-1 (GRX-1). In virus-infected GRX-1 knockdown cells, phosphorylation, homodimerization and nuclear translocation of IRF3 were not affected, but the transcriptional activity of IRF3 and the expression of interferon-beta (IFNbeta), were severely reduced. We show that deglutathionylation of IRF3 is necessary for efficient interaction of IRF3 with CBP, an event essential for transcriptional activation of the interferon genes. Taken together, these findings reveal a crucial role for S-glutathionylation and GRX-1 in controlling the activation of IRF3 and IFNbeta gene expression.
干扰素调节因子3（IRF3）是干扰素基因的重要转录调节因子。IRF3以潜伏构象组成性地存在于细胞质中。在仙台病毒感染的细胞中，IRF3发生磷酸化、形成同源二聚体、转位至细胞核，与靶基因结合并通过与CBP/p300共激活因子相互作用激活转录。在本研究中，我们报道在未感染的细胞中，IRF3通过S-谷胱甘肽化进行翻译后修饰。病毒感染后，它经历一个由细胞质酶谷氧还蛋白-1（GRX-1）控制的去谷胱甘肽化步骤。在病毒感染的GRX-1敲低细胞中，IRF3的磷酸化、同源二聚化和核转位未受影响，但IRF3的转录活性和干扰素-β（IFNβ）的表达严重降低。我们表明，IRF3的去谷胱甘肽化对于IRF3与CBP的有效相互作用是必需的，而这一事件对于干扰素基因的转录激活至关重要。综上所述，这些发现揭示了S-谷胱甘肽化和GRX-1在控制IRF3激活和IFNβ基因表达中的关键作用。
