scholarly journals Interferon Regulatory Factor 3 Is a Cellular Partner of Rotavirus NSP1

2002 ◽  
Vol 76 (18) ◽  
pp. 9545-9550 ◽  
Author(s):  
Joel W. Graff ◽  
Dana N. Mitzel ◽  
Carla M. Weisend ◽  
Michelle L. Flenniken ◽  
Michele E. Hardy
Keyword(s):  
Nonstructural Protein ◽  
Interferon Regulatory Factor ◽  
Interferon Response ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
C Terminus ◽  
Cellular Partner ◽  
Infected Cells ◽  
Two Hybrid ◽  
Interaction Trap

ABSTRACT The rotavirus nonstructural protein NSP1 is the least conserved protein in the rotavirus genome, and its function in the replication cycle is not known. We employed NSP1 as bait in the yeast two-hybrid interaction trap to identify candidate cellular partners of NSP1 that may provide clues to its function. Interferon regulatory factor 3 (IRF-3) was identified as an NSP1 interactor. NSP1 synthesized in rotavirus-infected cells bound IRF-3 in a glutathione S-transferase pull-down assay, indicating that the interaction was not unique to the two-hybrid system. NSP1 of murine rotavirus strain EW also interacted with IRF-3. NSP1 deletion and point mutants were constructed to map domains important in the interaction between NSP1 and IRF-3. The data suggest that a binding domain resides in the C terminus of NSP1 and that the N-terminal conserved zinc finger is important but not sufficient to mediate binding to IRF-3. We predict that a role for NSP1 in rotavirus-infected cells is to inhibit activation of IRF-3 and diminish the cellular interferon response.

scholarly journals Human Rhinovirus Attenuates the Type I Interferon Response by Disrupting Activation of Interferon Regulatory Factor 3

2006 ◽  
Vol 80 (10) ◽  
pp. 5021-5031 ◽  
Author(s):  
Tao Peng ◽  
Swathi Kotla ◽  
Roger E. Bumgarner ◽  
Kurt E. Gustin
Keyword(s):  
Type I Interferon ◽  
Transcriptional Response ◽  
Interferon Regulatory Factor ◽  
Alveolar Epithelial Cells ◽  
Interferon Response ◽  
Type I ◽  
Regulatory Factor ◽  
Full Spectrum ◽  
Interferon Regulatory Factor 3 ◽  
Infected Cells

ABSTRACT The type I interferon (IFN) response requires the coordinated activation of the latent transcription factors NF-κB, interferon regulatory factor 3 (IRF-3), and ATF-2, which in turn activate transcription from the IFN-β promoter. Synthesis and subsequent secretion of IFN-β activate the Jak/STAT signaling pathway, resulting in the transcriptional induction of the full spectrum of antiviral gene products. We utilized high-density microarrays to examine the transcriptional response to rhinovirus type 14 (RV14) infection in HeLa cells, with particular emphasis on the type I interferon response and production of IFN-β. We found that, although RV14 infection results in altered levels of a wide variety of host mRNAs, induction of IFN-β mRNA or activation of the Jak/STAT pathway is not seen. Prior work has shown, and our results have confirmed, that NF-κB and ATF-2 are activated following infection. Since many viruses are known to target IRF-3 to inhibit the induction of IFN-β mRNA, we analyzed the status of IRF-3 in infected cells. IRF-3 was translocated to the nucleus and phosphorylated in RV14-infected cells. Despite this apparent activation, very little homodimerization of IRF-3 was evident following infection. Similar results in A549 lung alveolar epithelial cells demonstrated the biological relevance of these findings to RV14 pathogenesis. In addition, prior infection of cells with RV14 prevented the induction of IFN-β mRNA following treatment with double-stranded RNA, indicating that RV14 encodes an activity that specifically inhibits this innate host defense pathway. Collectively, these results indicate that RV14 infection inhibits the host type I interferon response by interfering with IRF-3 activation.

scholarly journals Loss of Interferon Regulatory Factor 3 in Cells Infected with Classical Swine Fever Virus Involves the N-Terminal Protease, Npro

2005 ◽  
Vol 79 (11) ◽  
pp. 7239-7247 ◽  
Author(s):  
S. Anna La Rocca ◽  
Rebecca J. Herbert ◽  
Helen Crooke ◽  
Trevor W. Drew ◽  
Thomas E. Wileman ◽  
...  
Keyword(s):  
Classical Swine Fever Virus ◽  
Viral Protein ◽  
Sindbis Virus ◽  
Classical Swine Fever ◽  
Interferon Regulatory Factor ◽  
Fever Virus ◽  
Luciferase Reporter ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Infected Cells

ABSTRACT We show that cells infected with the pestivirus classical swine fever virus (CSFV) fail to produce alpha/beta interferon not only following treatment with double-stranded RNA but also after superinfection with a heterologous virus, the alphavirus Sindbis virus, a virus shown to normally induce interferon. We investigated whether the inhibition of interferon synthesis by CSFV involved a block in interferon regulatory factor 3 (IRF3) activity. Cells infected with CSFV exhibited a lack of translocation of green fluorescent protein-IRF3 to the nucleus; however, constitutive shuttling of IRF3 was not blocked, since it could still accumulate in the nucleus in the presence of leptomycin B. Interestingly subcellular fractionation analysis showed that IRF3 was lost from the cytoplasm of infected cells from 18 h postinfection onwards. Using IRF3 promoter-luciferase reporter constructs, we demonstrate that loss of IRF3 was due to an inhibition of transcription of the IRF3 gene in CSFV-infected cells. Further, we investigated which viral protein may be responsible for the inhibition of interferon and loss of IRF3. We used cell lines expressing the CSFV N-terminal protease (Npro) to show that this single viral protein, unique to pestiviruses, inhibited interferon production in response to Sindbis virus. In addition to being lost from CSFV-infected cells, IRF3 was lost from Npro-expressing cells. The results demonstrate a novel viral evasion of innate host defenses, where interferon synthesis is prevented by inhibiting transcription of IRF3 in CSFV-infected cells.

scholarly journals Hsp90 Regulates Activation of Interferon Regulatory Factor 3 and TBK-1 Stabilization in Sendai Virus-infected Cells

2006 ◽  
Vol 17 (3) ◽  
pp. 1461-1471 ◽  
Author(s):  
Kai Yang ◽  
Hexin Shi ◽  
Rong Qi ◽  
Shaogang Sun ◽  
Yujie Tang ◽  
...  
Keyword(s):  
Sendai Virus ◽  
Specific Interaction ◽  
Hybrid Approach ◽  
Specific Inhibitor ◽  
Interferon Regulatory Factor ◽  
Dominant Negative ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Infected Cells ◽  
Irf3 Activation

Interferon regulatory factor 3 (IRF3) plays a crucial role in mediating cellular responses to virus intrusion. The protein kinase TBK1 is a key regulator inducing phosphorylation of IRF3. The regulatory mechanisms during IRF3 activation remain poorly characterized. In the present study, we have identified by yeast two-hybrid approach a specific interaction between IRF3 and chaperone heat-shock protein of 90 kDa (Hsp90). The C-terminal truncation mutant of Hsp90 is a strong dominant-negative inhibitor of IRF3 activation. Knockdown of endogenous Hsp90 by RNA interference attenuates IRF3 activation and its target gene expressions. Alternatively, Hsp90-specific inhibitor geldanamycin (GA) dramatically reduces expression of IRF3-regulated interferon-stimulated genes and abolishes the cytoplasm-to-nucleus translocation and DNA binding activity of IRF3 in Sendai virus-infected cells. Significantly, virus-induced IRF3 phosphorylation is blocked by GA, whereas GA does not affect the protein level of IRF3. In addition, TBK1 is found to be a client protein of Hsp90 in vivo. Treatment of 293 cells with GA interferes with the interaction of TBK1 and Hsp90, resulting in TBK1 destabilization and its subsequent proteasome-mediated degradation. Besides maintaining stability of TBK1, Hsp90 also forms a novel complex with TBK1 and IRF3, which brings TBK1 and IRF3 dynamically into proximity and facilitates signal transduction from TBK1 to IRF3. Our study uncovers an essential role of Hsp90 in the virus-induced activation of IRF3.

scholarly journals Bunyamwera Virus Nonstructural Protein NSs Counteracts Interferon Regulatory Factor 3-Mediated Induction of Early Cell Death

2003 ◽  
Vol 77 (14) ◽  
pp. 7999-8008 ◽  
Author(s):  
Alain Kohl ◽  
Reginald F. Clayton ◽  
Friedemann Weber ◽  
Anne Bridgen ◽  
Richard E. Randall ◽  
...  
Keyword(s):  
Cell Death ◽  
Defense Mechanism ◽  
Nonstructural Protein ◽  
Interferon Regulatory Factor ◽  
Wild Type Virus ◽  
Wild Type ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Viral Spread ◽  
Bunyamwera Virus

ABSTRACT The genome of Bunyamwera virus (BUN; family Bunyaviridae, genus Orthobunyavirus) consists of three segments of negative-sense RNA. The smallest segment, S, encodes two proteins, the nonstructural protein NSs, which is nonessential for viral replication and transcription, and the nucleocapsid protein N. Although a precise role in the replication cycle has yet to be attributed to NSs, it has been shown that NSs inhibits the induction of alpha/beta interferon, suggesting that it plays a part in counteracting the host antiviral defense. A defense mechanism to limit viral spread is programmed cell death by apoptosis. Here we show that a recombinant BUN that does not express NSs (BUNdelNSs) induces apoptotic cell death more rapidly than wild-type virus. Screening for apoptosis pathways revealed that the proapoptotic transcription factor interferon regulatory factor 3 (IRF-3) was activated by both wild-type BUN and BUNdelNSs infection, but only wild-type BUN was able to suppress signaling downstream of IRF-3. Studies with a BUN minireplicon system showed that active replication induced an IRF-3-dependent promoter, which was suppressed by the NSs protein. In a cell line (P2.1) defective in double-stranded RNA signaling due to low levels of IRF-3, induction of apoptosis was similar for wild-type BUN and BUNdelNSs. These data suggest that the BUN NSs protein can delay cell death in the early stages of BUN infection by inhibiting IRF-3-mediated apoptosis.

scholarly journals Identification of TRAIL as an Interferon Regulatory Factor 3 Transcriptional Target

2005 ◽  
Vol 79 (14) ◽  
pp. 9320-9324 ◽  
Author(s):  
Jessica R. Kirshner ◽  
Alla Y. Karpova ◽  
Maren Kops ◽  
Peter M. Howley
Keyword(s):  
Viral Infection ◽  
Virus Production ◽  
Interferon Regulatory Factor ◽  
Progeny Virus ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Apoptosis Pathway ◽  
Infected Cells ◽  
Transcriptional Induction ◽  
Transcriptional Target

ABSTRACT Interferon production and apoptosis in virus-infected cells are necessary to prevent progeny virus production and to eliminate infected cells. Paramyxovirus infection induces apoptosis through interferon regulatory factor 3 (IRF-3), but the exact mechanism of how IRF-3 functions is unknown. We show that IRF-3 is involved in the transcriptional induction of TRAIL, a key player in the apoptosis pathway. IRF-3 upregulates TRAIL transcription following viral infection and binds an interferon-stimulated response element in the TRAIL promoter. The mRNA for TRAIL and its receptor, DR5, are induced following viral infection. These studies identify TRAIL as a novel IRF-3 transcriptional target.

scholarly journals Classical Swine Fever Virus Can Remain Virulent after Specific Elimination of the Interferon Regulatory Factor 3-Degrading Function of Npro

2008 ◽  
Vol 83 (2) ◽  
pp. 817-829 ◽  
Author(s):  
Nicolas Ruggli ◽  
Artur Summerfield ◽  
Ana R. Fiebach ◽  
Laurence Guzylack-Piriou ◽  
Oliver Bauhofer ◽  
...  
Keyword(s):  
Classical Swine Fever Virus ◽  
Nonstructural Protein ◽  
Classical Swine Fever ◽  
Interferon Regulatory Factor ◽  
Fever Virus ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Amino Terminal ◽  
Alpha Beta

ABSTRACT Pestiviruses prevent alpha/beta interferon (IFN-α/β) production by promoting proteasomal degradation of interferon regulatory factor 3 (IRF3) by means of the viral Npro nonstructural protein. Npro is also an autoprotease, and its amino-terminal coding sequence is involved in translation initiation. We previously showed with classical swine fever virus (CSFV) that deletion of the entire Npro gene resulted in attenuation in pigs. In order to elaborate on the role of the Npro-mediated IRF3 degradation in classical swine fever pathogenesis, we searched for minimal amino acid substitutions in Npro that would specifically abrogate this function. Our mutational analyses showed that degradation of IRF3 and autoprotease activity are two independent but structurally overlapping functions of Npro. We describe two mutations in Npro that eliminate Npro-mediated IRF3 degradation without affecting the autoprotease activity. We also show that the conserved standard sequence at these particular positions is essential for Npro to interact with IRF3. Surprisingly, when these two mutations are introduced independently in the backbones of highly and moderately virulent CSFV, the resulting viruses are not attenuated, or are only partially attenuated, in 8- to 10-week-old pigs. This contrasts with the fact that these mutant viruses have lost the capacity to degrade IRF3 and to prevent IFN-α/β induction in porcine cell lines and monocyte-derived dendritic cells. Taken together, these results demonstrate that contrary to previous assumptions and to the case for other viral systems, impairment of IRF3-dependent IFN-α/β induction is not a prerequisite for CSFV virulence.

scholarly journals HIV Vpu Interferes with NF-κB Activity but Not with Interferon Regulatory Factor 3

2015 ◽  
Vol 89 (19) ◽  
pp. 9781-9790 ◽  
Author(s):  
Lara Manganaro ◽  
Elisa de Castro ◽  
Ana M. Maestre ◽  
Kevin Olivieri ◽  
Adolfo García-Sastre ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Surface Expression ◽  
Interferon Regulatory Factor ◽  
Interferon Response ◽  
Cell Surface Expression ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Type 1 Interferon ◽  
Innate Immune Signaling

ABSTRACTThe accessory HIV protein Vpu inhibits a number of cellular pathways that trigger host innate restriction mechanisms. HIV Vpu-mediated degradation of tetherin allows efficient particle release and hampers the activation of the NF-κB pathway thereby limiting the expression of proinflammatory genes. In addition, Vpu reduces cell surface expression of several cellular molecules such as newly synthesized CD4. However, the role of HIV Vpu in regulating the type 1 interferon response to viral infection by degradation of the interferon regulatory factor 3 (IRF3) has been subject of conflicting reports. We therefore systematically investigated the expression of IRF3 in primary CD4+T cells and macrophages infected with HIV at different time points. In addition, we also tested the ability of Vpu to interfere with innate immune signaling pathways such as the NF-κB and the IRF3 pathways. We report here that HIV Vpu failed to degrade IRF3 in infected primary cells. Moreover, we observed that HIV NL4.3 Vpu had no effect on IRF3-dependent gene expression in reporter assays. On the other hand, HIV NL4.3 Vpu downmodulated NF-κB-dependent transcription. Mutation of two serines (positions 52 and 56) involved in the binding of NL4.3 Vpu to the βTrCP ubiquitin ligase abolishes its ability to inhibit NF-κB activity. Taken together, these results suggest that HIV Vpu regulates antiviral innate response in primary human cells by acting specifically on the NF-κB pathway.IMPORTANCEHIV Vpu plays a pivotal role in enhancing HIV infection by counteraction of Tetherin. However, Vpu also regulates host response to HIV infection by hampering the type 1 interferon response. The molecular mechanism by which Vpu inhibits the interferon response is still controversial. Here we report that Vpu affects interferon expression by inhibiting NF-κB activity without affecting IRF3 levels or activity. These data suggest that Vpu facilitates HIV infection by regulating NF-κB transcription to levels sufficient for viral transcription while limiting cellular responses to infection.

scholarly journals Interferon Regulatory Factor 3 Is Necessary for Induction of Antiviral Genes during Human Cytomegalovirus Infection

2006 ◽  
Vol 80 (2) ◽  
pp. 1032-1037 ◽  
Author(s):  
Victor R. DeFilippis ◽  
Bridget Robinson ◽  
Thomas M. Keck ◽  
Scott G. Hansen ◽  
Jay A. Nelson ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Global Gene Expression ◽  
Interferon Regulatory Factor ◽  
Dominant Negative ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Interferon Stimulated Genes ◽  
Antiviral Genes ◽  
Infected Cells ◽  
Interfering Rna

ABSTRACT Viral infection activates interferon regulatory factor 3 (IRF3), a cofactor for the induction of interferon-stimulated genes (ISGs). The role of IRF3 in the activation of ISGs by human cytomegalovirus (HCMV) is controversial despite the fact that HCMV has consistently been shown to induce ISGs during infection of fibroblasts. To address the function of IRF3 in HCMV-mediated ISG induction, we monitored ISG expression and global gene expression in HCMV-infected cells in which IRF3 function had been depleted by small interfering RNA or blocked by dominant negative IRF3. A specific reduction of ISG induction was observed, whereas other transcripts were unaffected. We therefore conclude that IRF3 specifically regulates ISG induction during the initial phase of HCMV infection.

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