期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2007
卷号：104
期号：9
页码：3402-3407
DOI：10.1073/pnas.0611559104
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Host defense consists of two main aspects, namely, immune response to invading pathogens and suppression of tumor development. A family of transcription factors, IFN regulatory factors (IRFs), has recently gained much attention in terms of its critical role in linking these two aspects of host defense, wherein IRF5 was previously shown to play a critical role in the induction of proinflammatory cytokines by activation of Toll-like receptors. In the present study, using IRF5 gene-targeted mice (Irf5-/- mice), we demonstrate another facet of the IRF5 function in the regulation of immune response and tumor suppression. We show that IRF5 is critical for antiviral immunity by showing that Irf5-/- mice are highly vulnerable to viral infections, accompanied by a decrease in type I IFN induction in the sera. Furthermore, we show that Irf5-/- fibroblasts are resistant to apoptosis upon viral infection, resulting in an enhanced viral propagation. Finally, we provide evidence that IRF5 is critical for the induction of apoptosis, but not in cell cycle arrest, in response to DNA damage and that IRF5 functions as a tumor suppressor by acting on a pathway that may be distinct from that for p53. These results, together with the dual regulation of IRF5 gene expression by IFN signaling and p53, may provide a new link in the transcriptional network underlying antiviral immunity and tumor suppression.
