Grass Carp Reovirus Nonstructural Proteins Avoid Host Antiviral Immune Response by Targeting the RLR Signaling Pathway

ABSTRACT The phosphatase Cdc25A plays an important role in cell cycle regulation by dephosphorylating its substrates, such as cyclin-dependent kinases. In this study, we demonstrate that Cdc25A negatively regulates RIG-I-mediated antiviral signaling. We found that ectopic expression of Cdc25A in 293T cells inhibits the activation of beta interferon (IFN-β) induced by Sendai virus and poly(I·C), while knockdown of Cdc25A enhances the transcription of IFN-β stimulated by RNA virus infection. The inhibitory effect of Cdc25A on the antiviral immune response is mainly dependent on its phosphatase activity. Data from a luciferase assay indicated that Cdc25A can inhibit TBK1-mediated activation of IFN-β. Further analysis indicated that Cdc25A can interact with TBK1 and reduce the phosphorylation of TBK1 at S172, which in turn decreases the phosphorylation of its downstream substrate IRF3. Consistently, knockdown of Cdc25A upregulates the phosphorylation of both TBK1-S172 and IRF3 in Sendai virus-infected or TBK1-transfected 293T cells. In addition, we confirmed that Cdc25A can directly dephosphorylate TBK1-S172-p. These results demonstrate that Cdc25A inhibits the antiviral immune response by reducing the active form of TBK1. Using herpes simplex virus 1 (HSV-1) infection, an IFN-β reporter assay, and reverse transcription-quantitative PCR (RT-qPCR), we demonstrated that Cdc25A can also inhibit DNA virus-induced activation of IFN-β. Using a vesicular stomatitis virus (VSV) infection assay, we confirmed that Cdc25A can repress the RIG-I-like receptor (RLR)-mediated antiviral immune response and influence the antiviral status of cells. In conclusion, we demonstrate that Cdc25A negatively regulates the antiviral immune response by inhibiting TBK1 activity. IMPORTANCE The RLR-mediated antiviral immune response is critical for host defense against RNA virus infection. However, the detailed mechanism for balancing the RLR signaling pathway in host cells is not well understood. We found that the phosphatase Cdc25A negatively regulates the RNA virus-induced innate immune response. Our studies indicate that Cdc25A inhibits the RLR signaling pathway via its phosphatase activity. We demonstrated that Cdc25A reduces TBK1 activity and consequently restrains the activation of IFN-β transcription as well as the antiviral status of nearby cells. We showed that Cdc25A can also inhibit DNA virus-induced activation of IFN-β. Taken together, our findings uncover a novel function and mechanism for Cdc25A in regulating antiviral immune signaling. These findings reveal Cdc25A as an important negative regulator of antiviral immunity and demonstrate its role in maintaining host cell homeostasis following viral infection.

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Grass Carp Reovirus (GCRV) Giving Its All to Suppress IFN Production by Countering MAVS-TBK1 Activation

10.1101/792408 ◽

2019 ◽

Author(s):

Long-Feng Lu ◽

Zhuo-Cong Li ◽

Can Zhang ◽

Xiao-Yu Zhou ◽

Yu Zhou ◽

...

Keyword(s):

Signaling Pathway ◽

Grass Carp ◽

Biological Effects ◽

Viral Proteins ◽

Host Cells ◽

Signaling Transduction ◽

Grass Carp Reovirus ◽

Fish Virus ◽

Fish Viruses ◽

Mitochondrial Antiviral Signaling

AbstractAs a crucial signaling pathway for interferon (IFN) production, the RIG-I-like receptor (RLR) axis is usually the host target of viruses to enhance viral infection. To date, though immune evasion methods to contrapose IFN production have been characterized for a series of terrestrial viruses, the strategies employed by fish viruses remain unclear. Here, we report that all grass carp reovirus (GCRV) proteins encoded by segments S1 to S11 interact with fish RLR factors, specifically for mitochondrial antiviral signaling protein-TANK-binding kinase 1 (MAVS-TBK1) signaling transduction, leading to decreased IFN expression. First, the GCRV viral proteins blunted the MAVS-induced expression of IFN but had little effect on TBK1-induced IFN expression. Subsequently, interestingly, co-immunoprecipitation experiments demonstrated that all GCRV viral proteins interacted with several RLR cascades, especially with TBK1. To further illustrate the mechanisms of these interactions between GCRV viral proteins and host RLRs, two of the viral proteins, NS79 (S4) and VP3 (S3), were selected as representative proteins for the study. The obtained data demonstrated that NS79 did not affect the stability of the host RLR protein, but was phosphorylated by gcTBK1, leading to the reduction of host substrate gcIRF3/7 phosphorylation. On the other hand, VP3 degraded gcMAVS and the degradation was significantly reversed by 3-MA. The biological effects of both NS79 and VP3 were consistently found to be related to the suppression of IFN expression and the promotion of viral evasion. Our findings shed light on the special evasion mechanism utilized by fish virus through IFN regulation, which might differ between fish and mammals.Author summaryThe RLR signaling pathway is crucial for IFN induction when host cells are infected with virus and RLR factors are targeted by virus. To date, the evasion mechanisms of fish viruses remain mysterious. In this study, we reveal that all 11 GCRV proteins interact with fish RLR factors and suppress the activation of MAVS-TBK1 signaling transduction, leading to the reduction of IFN expression. Two viral proteins were employed as examples to investigate the different evasion mechanisms of GCRV. These findings reveal the novel countermeasures used by fish virus to avoid the host IFN response.

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Histone H2A Nuclear/Cytoplasmic Trafficking Is Essential for Negative Regulation of Antiviral Immune Response and Lysosomal Degradation of TBK1 and IRF3

Frontiers in Immunology ◽

10.3389/fimmu.2021.771277 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xiao Man Wu ◽

Hong Fang ◽

Jie Zhang ◽

Yong Hong Bi ◽

Ming Xian Chang

Keyword(s):

Immune Response ◽

Protein Degradation ◽

Signaling Pathway ◽

Early Stage ◽

Negative Regulation ◽

Histone H2a ◽

Antiviral Immune Response ◽

Functional Complex ◽

Host Innate Immune Response

Histone H2A is a nuclear molecule tightly associated in the form of the nucleosome. Our previous studies have demonstrated the antibacterial property of piscine H2A variants against gram-negative bacteria Edwardsiella piscicida and Gram-positive bacteria Streptococcus agalactiae. In this study, we show the function and mechanism of piscine H2A in the negative regulation of RLR signaling pathway and host innate immune response against spring viremia of carp virus (SVCV) infection. SVCV infection significantly inhibits the expression of histone H2A during an early stage of infection, but induces the expression of histone H2A during the late stage of infection such as at 48 and 72 hpi. Under normal physiological conditions, histone H2A is nuclear-localized. However, SVCV infection promotes the migration of histone H2A from the nucleus to the cytoplasm. The in vivo studies revealed that histone H2A overexpression led to the increased expression of SVCV gene and decreased survival rate. The overexpression of histone H2A also significantly impaired the expression levels of those genes involved in RLR antiviral signaling pathway. Furthermore, histone H2A targeted TBK1 and IRF3 to promote their protein degradation via the lysosomal pathway and impair the formation of TBK1-IRF3 functional complex. Importantly, histone H2A completely abolished TBK1-mediated antiviral activity and enormously impaired the protein expression of IRF3, especially nuclear IRF3. Further analysis demonstrated that the inhibition of histone H2A nuclear/cytoplasmic trafficking could relieve the protein degradation of TBK1 and IRF3, and blocked the negative regulation of histone H2A on the SVCV infection. Collectively, our results suggest that histone H2A nuclear/cytoplasmic trafficking is essential for negative regulation of RLR signaling pathway and antiviral immune response in response to SVCV infection.

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Involvement of interferon regulatory factor 3 from the barbel chub Squaliobarbus curriculus in the immune response against grass carp reovirus

Gene ◽

10.1016/j.gene.2018.01.048 ◽

2018 ◽

Vol 648 ◽

pp. 5-11 ◽

Cited By ~ 6

Author(s):

Ronghua Wang ◽

Yaoguo Li ◽

Zhiyu Zhou ◽

Qiaolin Liu ◽

Lingbing Zeng ◽

...

Keyword(s):

Immune Response ◽

Grass Carp ◽

Interferon Regulatory Factor ◽

Regulatory Factor ◽

Interferon Regulatory Factor 3 ◽

Grass Carp Reovirus ◽

Squaliobarbus Curriculus

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5-Hydroxymethylfurfural Enhances the Antiviral Immune Response in Macrophages through the Modulation of RIG-I-Mediated Interferon Production and the JAK/STAT Signaling Pathway

ACS Omega ◽

10.1021/acsomega.1c03862 ◽

2021 ◽

Author(s):

Han Zou ◽

Tingyue Wu ◽

Yuan Wang ◽

Yanhua Kang ◽

Qingye Shan ◽

...

Keyword(s):

Immune Response ◽

Signaling Pathway ◽

Interferon Production ◽

Antiviral Immune Response ◽

Stat Signaling

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HIV-1 and HIV-2 differentially regulate NF-κB activity during the late stages of the replication cycle through BST-2/tetherin antagonism

10.1101/2020.05.11.088385 ◽

2020 ◽

Author(s):

François E. Dufrasne ◽

Géraldine Dessilly ◽

Mara Lucchetti ◽

Kate Soumillion ◽

Eléonore Ngyuvula ◽

...

Keyword(s):

Immune Response ◽

T Cells ◽

Viral Replication ◽

Signaling Pathway ◽

Replication Cycle ◽

Immune Control ◽

Antiviral Immune Response ◽

Late Stages ◽

Hiv 1 ◽

Tetherin Antagonism

ABSTRACTHIV-2 is the second causative agent of AIDS and is commonly considered as an attenuated form of retroviral infection. Most of HIV-2-infected individuals display a slow-progressing disease, lower viral loads and a stronger immunological control of viral infection as compared with HIV-1-infected patients. The main hypothesis that could explain the difference of disease progression between HIV-1 and HIV-2 implies a more efficient T cell–mediated immunity in the control of HIV-2 infection. Herein, we investigate the effects of the HIV-2 envelope glycoprotein (Env) and its antitetherin function in the NF-κB signaling pathway during single-round infection of CD4+ T cells. First, we report an essential role of the Env cytoplasmic tail (CT) in the activation of this signaling pathway and we also demonstrate that the HIV-2 Env CT activates NF-κB in a TRAF6-dependent but TAK1-independent manner. Further, we show that HIV-2 reference strains and clinical isolates are unable to completely inhibit NF-κB mainly via the Env-mediated BST-2/tetherin antagonism in the late stages of the viral replication cycle in CD4+ T cells, in striking contrast to the HIV-1 Vpu-mediated counteraction of tetherin. We observe that this inability of HIV-2 to suppress NF-κB signaling pathway promotes stimulation of numerous genes involved in the antiviral immune response, such as il-6, il-21 and ifn-β genes. Therefore, HIV-1 and HIV-2 differentially regulate the NF-κB-induced antiviral immune response mainly through the BST-2/tetherin antagonism. These new insights highlight molecular mechanisms determining, at least partly, the distinct immune control and disease outcomes of HIV-1 and HIV-2 infections.IMPORTANCEThis study explores how HIV-1 and HIV-2 diverge in their regulation of the NF-κB signaling pathway. We revealed that HIV-2 fails to completely inhibit NF-κB activity, thereby inducing a stronger antiviral response than HIV-1. We demonstrated that the ability to antagonize the cellular restriction factor BST-2/tetherin largely governs the regulation of the NF-κB pathway: at the late stages of the viral replication cycle, HIV-1 Vpu blocks this pathway whereas HIV-2 Env does not. We also demonstrated that several NF-κB-targeted genes are upregulated in CD4+ T cells infected with HIV-2, but not with HIV-1. This stronger NF-κB-induced antiviral response may explain the better immune control of HIV-2 infection and the differences between HIV-1 and HIV-2 pathogenesis. Moreover, we observed in this study that non-pathogenic isolates of HIV-2 have an impaired NF-κB inhibitory capacity compared to pathogenic ones.

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