The RNA Helicase DHX16 Provides Specific Viral RNA for RIG-I to Trigger Innate Antiviral Immunity
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PROVIDER: PRJNA706691 | ENA |
REPOSITORIES: ENA
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2019-10-02 | PXD013191 | Pride
Project description:RIG-I is thought to be the most important sensor of influenza virus infection and plays critical roles in the recognition of cytoplasmic dsRNA and activation of type I IFNs and initiates the innate antiviral immune responses. How the binding of viral RNA to and activation of RIG-I are regulated remains enigmatic. Here, by an affinity proteomics approach with viral RNA as the bait, we found that IFI16, previously identified as a DNA sensor, was significantly induced both in vitro and in vivo during influenza virus infection. Using an IFI16 knockout cells and p204-deficient mice model, we demonstrated that IFI16 enhanced RIG-I-mediated production of type I IFNs and thereby inhibited viral replication during influenza virus infection. Furthermore, we showed that IFI16 regulated the RIG-I signaling by enhancing its transcriptional expression through recruitment of RNA Pol II to the RIG-I promoter. We also verified that IFI16 directly interacted with both viral RNA by HINa domain and associated with RIG-I through its PYRIN domain as well as promoted influenza virus-induced K63-linked polyubiquitination of RIG-I. In addition, we found that IFI16 lost its ability to inhibit viral replication in the absence of RIG-I in virus-infected cells. These results indicate that IFI16 is a key regulator of the RIG-I signaling during antiviral innate immune responses, which highlights a novel mechanism of IFI16 in IAV and other RNA viruses infection, expands our knowledge in antiviral innate immunity, and suggests its possible use as a new strategies to manipulate antiviral responses.
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2020-09-17 | GSE158122 | GEO
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Project description:In mammalian somatic cells, the relative contribution of RNAi and the type I interferon response during viral infection is unclear. The apparent inefficiency of antiviral RNAi might be due to self-limiting properties and mitigating co-factors of the key enzyme Dicer. In particular, the helicase domain of human Dicer appears to be an important restriction factor of its activity. Here, we study the involvement of several helicase-truncated mutants of human Dicer in the antiviral response. All deletion mutants display a PKR-dependent antiviral phenotype against certain viruses, and one of them, Dicer N1, acts in a completely RNAi-independent manner. Transcriptomic analyses show that many genes from the interferon and inflammatory response pathways are upregulated in Dicer N1-expressing cells. We show that some of these genes are controlled by NF-kB and that blocking this pathway abrogates the antiviral phenotype of Dicer N1. Our findings highlight the crosstalk between Dicer, PKR, and the NF-kB pathway, and suggest that human Dicer may have repurposed its helicase domain to prevent basal activation of antiviral and inflammatory pathways.
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