NF90 Exerts Antiviral Activity through Regulation of PKR Phosphorylation and Stress Granules in Infected Cells
NF90 Exerts Antiviral Activity through Regulation of PKR Phosphorylation and Stress Granules in Infected Cells
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DOI：
10.4049/jimmunol.1302813
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发表时间：
2014-04
期刊：
影响因子：
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通讯作者：
Xi Wen;Xiaofeng Huang;B. Mok;Yixin Chen;Min Zheng;S. Lau;Pui Wang;Wenjun Song;D. Jin;K. Yuen;Honglin Chen
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文献类型：
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作者：
Xi Wen;Xiaofeng Huang;B. Mok;Yixin Chen;Min Zheng;S. Lau;Pui Wang;Wenjun Song;D. Jin;K. Yuen;Honglin Chen
NF 90被证明对几种病毒表现出广泛的抗病毒活性，但详细的机制仍不清楚。在这项研究中，我们研究了NF 90通过蛋白激酶（PKR）相关的翻译调控介导的病毒复制抑制作用的分子基础。我们首先在哺乳动物细胞中验证了NF 90和PKR之间的相互作用，并表明NF 90通过其C-末端与PKR相互作用，并且这种相互作用不依赖于NF 90 RNA结合特性。我们进一步表明，NF 90的敲低导致响应dsRNA诱导和流感病毒感染的PKR磷酸化水平显著降低。我们还发现，高浓度的NF 90对PKR磷酸化表现出负调节作用，可能是通过C-末端RNA结合结构域竞争dsRNA。PKR活化对于响应dsRNA诱导的应激颗粒的形成是必不可少的。我们的研究结果表明，NF 90是一个组成部分的应力颗粒。在NF 90敲除细胞中，dsRNA处理诱导的应激颗粒水平显著低于对照细胞。使用特异性减弱其抑制PKR活化能力的NS 1突变甲型流感病毒获得了NF 90-PKR抗病毒途径的进一步证据。这种突变病毒在NF 90敲低的细胞中从野生型病毒复制，但在乱序对照细胞或Vero细胞中没有，这表明NF 90的抗病毒功能是通过与PKR相互作用发生的。综上所述，这些结果揭示了一个尚未确定的宿主抗病毒机制，其中NF 90上调PKR磷酸化限制病毒感染。
NF90 was shown to exhibit broad antiviral activity against several viruses, but detailed mechanisms remain unclear. In this study, we examined the molecular basis for the inhibitory effect of NF90 on virus replication mediated through protein kinase (PKR)-associated translational regulation. We first verified the interaction between NF90 and PKR in mammalian cells and showed that NF90 interacts with PKR through its C-terminal and that the interaction is independent of NF90 RNA-binding properties. We further showed that knockdown of NF90 resulted in significantly lower levels of PKR phosphorylation in response to dsRNA induction and influenza virus infection. We also showed that high concentrations of NF90 exhibit negative regulatory effects on PKR phosphorylation, presumably through competition for dsRNA via the C-terminal RNA-binding domain. PKR activation is essential for the formation of stress granules in response to dsRNA induction. Our results showed that NF90 is a component of stress granules. In NF90-knockdown cells, dsRNA treatment induced significantly lower levels of stress granules than in control cells. Further evidence for an NF90–PKR antiviral pathway was obtained using an NS1 mutated influenza A virus specifically attenuated in its ability to inhibit PKR activation. This mutant virus replicated indistinguishably from wild-type virus in NF90-knockdown cells, but not in scrambled control cells or Vero cells, indicating that NF90’s antiviral function occurs through interaction with PKR. Taken together, these results reveal a yet-to-be defined host antiviral mechanism in which NF90 upregulation of PKR phosphorylation restricts virus infection.