scholarly journals Inhibition of Beta Interferon Induction by Severe Acute Respiratory Syndrome Coronavirus Suggests a Two-Step Model for Activation of Interferon Regulatory Factor 3

2005 ◽  
Vol 79 (4) ◽  
pp. 2079-2086 ◽  
Author(s):  
Martin Spiegel ◽  
Andreas Pichlmair ◽  
Luis Martínez-Sobrido ◽  
Jerome Cros ◽  
Adolfo García-Sastre ◽  
...  
Keyword(s):  
Virus Infection ◽  
Severe Acute Respiratory Syndrome ◽  
Promoter Activity ◽  
Nuclear Transport ◽  
Interferon Regulatory Factor ◽  
Creb Binding Protein ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Control Virus ◽  
Novel Coronavirus

ABSTRACT Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus termed SARS-CoV. We and others have previously shown that the replication of SARS-CoV can be suppressed by exogenously added interferon (IFN), a cytokine which is normally synthesized by cells as a reaction to virus infection. Here, we demonstrate that SARS-CoV escapes IFN-mediated growth inhibition by preventing the induction of IFN-β. In SARS-CoV-infected cells, no endogenous IFN-β transcripts and no IFN-β promoter activity were detected. Nevertheless, the transcription factor interferon regulatory factor 3 (IRF-3), which is essential for IFN-β promoter activity, was transported from the cytoplasm to the nucleus early after infection with SARS-CoV. However, at a later time point in infection, IRF-3 was again localized in the cytoplasm. By contrast, IRF-3 remained in the nucleus of cells infected with the IFN-inducing control virus Bunyamwera delNSs. Other signs of IRF-3 activation such as hyperphosphorylation, homodimer formation, and recruitment of the coactivator CREB-binding protein (CBP) were found late after infection with the control virus but not with SARS-CoV. Our data suggest that nuclear transport of IRF-3 is an immediate-early reaction to virus infection and may precede its hyperphosphorylation, homodimer formation, and binding to CBP. In order to escape activation of the IFN system, SARS-CoV appears to block a step after the early nuclear transport of IRF-3.

Interferon regulatory factor 3-dependent responses to lipopolysaccharide are selectively blunted in cord blood cells

Blood ◽  
2006 ◽  
Vol 109 (7) ◽  
pp. 2887-2893 ◽  
Author(s):  
Ezra Aksoy ◽  
Valentina Albarani ◽  
Muriel Nguyen ◽  
Jean-Francois Laes ◽  
Jean-Louis Ruelle ◽  
...  
Keyword(s):  
Cord Blood ◽  
Blood Cells ◽  
Nuclear Translocation ◽  
Interferon Regulatory Factor ◽  
Creb Binding Protein ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Altered Expression ◽  
Neonatal Blood ◽  
Inducible Genes

AbstractThe synthesis of interferon-β (IFNβ) and IFN-inducible factors elicited by lipopolysaccharide (LPS) depends on the transcriptional activity of interferon regulatory factor 3 (IRF-3) downstream of Toll-like receptor-4 (TLR4). To examine the ability of human newborns to mount TLR4-mediated IRF-3–dependent responses, we analyzed the pattern of genes expressed on the addition of LPS to cord blood or cord blood monocyte-derived dendritic cells (moDCs). Expression of IFNβ and IFN-inducible genes was selectively impaired in neonatal blood and moDCs as compared with their adult counterparts. This selective defect was confirmed by microarray experiments on moDCs. Altered expression of IFN-inducible genes was related to impaired IFNβ synthesis because IFNβ signaling was functional in neonatal moDCs. However, addition of exogenous IFNβ failed to restore LPS-induced IL-12p70 synthesis which was previously shown to be defective in neonatal moDCs. Although LPS-induced IRF-3 nuclear translocation was observed both in adult and neonatal moDCs, IRF-3 DNA-binding activity and association with the coactivator CREB-binding protein (CBP) were decreased in neonatal as compared with adult moDCs. We conclude that impaired IRF-3/CBP interaction in neonatal blood cells exposed to LPS is associated with impaired expression of IFNβ and IFN-inducible genes. Because IRF-3 activity is also required for IL-12p70 synthesis, our findings provide a molecular basis for the decreased ability of LPS-stimulated neonatal moDCs to elicit Th1-type responses.

scholarly journals Transcriptional Profiling of Interferon Regulatory Factor 3 Target Genes: Direct Involvement in the Regulation of Interferon-Stimulated Genes

2002 ◽  
Vol 76 (11) ◽  
pp. 5532-5539 ◽  
Author(s):  
Nathalie Grandvaux ◽  
Marc J. Servant ◽  
Benjamin tenOever ◽  
Ganes C. Sen ◽  
Siddarth Balachandran ◽  
...  
Keyword(s):  
Virus Infection ◽  
Target Genes ◽  
Expression Profiles ◽  
Expression System ◽  
Active Form ◽  
Interferon Regulatory Factor ◽  
Inducible Expression ◽  
Immediate Early ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3

ABSTRACT Ubiquitously expressed interferon regulatory factor 3 (IRF-3) is directly activated after virus infection and functions as a key activator of the immediate-early alpha/beta interferon (IFN) genes, as well as the RANTES chemokine gene. In the present study, a tetracycline-inducible expression system expressing a constitutively active form of IRF-3 (IRF-3 5D) was combined with DNA microarray analysis to identify target genes regulated by IRF-3. Changes in mRNA expression profiles of 8,556 genes were monitored after Tet-inducible expression of IRF-3 5D. Among the genes upregulated by IRF-3 were transcripts for several known IFN-stimulated genes (ISGs). Subsequent analysis revealed that IRF-3 directly induced the expression of ISG56 in an IFN-independent manner through the IFN-stimulated responsive elements (ISREs) of the ISG56 promoter. These results demonstrate that, in addition to its role in the formation of a functional immediate-early IFN-β enhanceosome, IRF-3 is able to discriminate among ISRE-containing genes involved in the establishment of the antiviral state as a direct response to virus infection.

scholarly journals Structural and Functional Analysis of Interferon Regulatory Factor 3: Localization of the Transactivation and Autoinhibitory Domains

1999 ◽  
Vol 19 (4) ◽  
pp. 2465-2474 ◽  
Author(s):  
Rongtuan Lin ◽  
Yael Mamane ◽  
John Hiscott
Keyword(s):  
Amino Acids ◽  
Dna Binding ◽  
Virus Infection ◽  
Nuclear Translocation ◽  
Sendai Virus ◽  
Interferon Regulatory Factor ◽  
Phosphorylation Sites ◽  
Transactivation Domain ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3

ABSTRACT The interferon regulatory factor 3 (IRF-3) gene encodes a 55-kDa protein which is expressed constitutively in all tissues. In unstimulated cells, IRF-3 is present in an inactive cytoplasmic form; following Sendai virus infection, IRF-3 is posttranslationally modified by protein phosphorylation at multiple serine and threonine residues located in the carboxy terminus. Virus-induced phosphorylation of IRF-3 leads to cytoplasmic to nuclear translocation of phosphorylated IRF-3, association with the transcriptional coactivator CBP/p300, and stimulation of DNA binding and transcriptional activities of virus-inducible genes. Using yeast and mammalian one-hybrid analysis, we now demonstrate that an extended, atypical transactivation domain is located in the C terminus of IRF-3 between amino acids (aa) 134 and 394. We also show that the C-terminal domain of IRF-3 located between aa 380 and 427 participates in the autoinhibition of IRF-3 activity via an intramolecular association with the N-terminal region between aa 98 and 240. After Sendai virus infection, an intermolecular association between IRF-3 proteins is detected, demonstrating a virus-dependent formation of IRF-3 homodimers; this interaction is also observed in the absence of virus infection with a constitutively activated form of IRF-3. Substitution of the C-terminal Ser-Thr phosphorylation sites with the phosphomimetic Asp in the region ISNSHPLSLTSDQ between amino acids 395 and 407 [IRF-3(5D)], but not the adjacent S385 and S386 residues, generates a constitutively activated DNA binding form of IRF-3. In contrast, substitution of S385 and S386 with either Ala or Asp inhibits both DNA binding and transactivation activities of the IRF-3(5D) protein. These studies thus define the transactivation domain of IRF-3, two domains that participate in the autoinhibition of IRF-3 activity, and the regulatory phosphorylation sites controlling IRF-3 dimer formation, DNA binding activity, and association with the CBP/p300 coactivator.

scholarly journals Analysis of Genes Induced by Sendai Virus Infection of Mutant Cell Lines Reveals Essential Roles of Interferon Regulatory Factor 3, NF-κB, and Interferon but Not Toll-Like Receptor 3

2005 ◽  
Vol 79 (7) ◽  
pp. 3920-3929 ◽  
Author(s):  
Christopher P. Elco ◽  
Jeanna M. Guenther ◽  
Bryan R. G. Williams ◽  
Ganes C. Sen
Keyword(s):  
Virus Infection ◽  
Cell Lines ◽  
Sendai Virus ◽  
Mutant Cell ◽  
Gene Induction ◽  
Interferon Regulatory Factor ◽  
Toll Like Receptor ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Infected Cells

ABSTRACT Sendai virus (SeV) infection causes the transcriptional induction of many cellular genes that are also induced by interferon (IFN) or double-stranded RNA (dsRNA). We took advantage of various mutant cell lines to investigate the putative roles of the components of the IFN and dsRNA signaling pathways in the induction of those genes by SeV. Profiling the patterns of gene expression in SeV-infected cells demonstrated that Toll-like receptor 3, although essential for gene induction by dsRNA, was dispensable for gene induction by SeV. In contrast, Jak1, which mediates IFN signaling, was required for the induction of a small subset of genes by SeV. NF-κB and interferon regulatory factor 3 (IRF-3), the two major transcription factors activated by virus infection, were essential for the induction of two sets of genes by SeV. As expected, some of the IRF-3-dependent genes, such as ISG56, were more strongly induced by SeV in IRF-3-overexpressing cells. Surprisingly, in those cells, a number of NF-κB-dependent genes, such as the A20 gene, were induced poorly. Using a series of cell lines expressing increasing levels of IRF-3, we demonstrated that the degree of induction of A20 mRNA, upon SeV infection, was inversely proportional to the cellular level of IRF-3, whereas that of ISG56 mRNA was directly proportional. Thus, IRF-3 can suppress the expression of NF-κB-dependent genes in SeV-infected cells.

scholarly journals Pestivirus NproDirectly Interacts with Interferon Regulatory Factor 3 Monomer and Dimer

2016 ◽  
Vol 90 (17) ◽  
pp. 7740-7747 ◽  
Author(s):  
Keerthi Gottipati ◽  
Luis Marcelo F. Holthauzen ◽  
Nicolas Ruggli ◽  
Kyung H. Choi
Keyword(s):  
Viral Infection ◽  
Binding Site ◽  
Classical Swine Fever Virus ◽  
Active Form ◽  
Classical Swine Fever ◽  
Proteasomal Degradation ◽  
Interferon Regulatory Factor ◽  
Creb Binding Protein ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3

ABSTRACTInterferon regulatory factor 3 (IRF3) is a transcription factor involved in the activation of type I alpha/beta interferon (IFN-α/β) in response to viral infection. Upon viral infection, the IRF3 monomer is activated into a phosphorylated dimer, which induces the transcription of interferon genes in the nucleus. Viruses have evolved several ways to target IRF3 in order to subvert the innate immune response. Pestiviruses, such as classical swine fever virus (CSFV), target IRF3 for ubiquitination and subsequent proteasomal degradation. This is mediated by the viral protein Nprothat interacts with IRF3, but the molecular details for this interaction are largely unknown. We used recombinant Nproand IRF3 proteins and show that Nprointeracts with IRF3 directly without additional proteins and forms a soluble 1:1 complex. The full-length IRF3 but not merely either of the individual domains is required for this interaction. The interaction between Nproand IRF3 is not dependent on the activation state of IRF3, since Nprobinds to a constitutively active form of IRF3 in the presence of its transcriptional coactivator, CREB-binding protein (CBP). The results indicate that the Npro-binding site on IRF3 encompasses a region that is unperturbed by the phosphorylation and subsequent activation of IRF3 and thus excludes the dimer interface and CBP-binding site.IMPORTANCEThe pestivirus N-terminal protease, Npro, is essential for evading the host's immune system by facilitating the degradation of interferon regulatory factor 3 (IRF3). However, the nature of the Nprointeraction with IRF3, including the IRF3 species (inactive monomer versus activated dimer) that Nprotargets for degradation, is largely unknown. We show that classical swine fever virus Nproand porcine IRF3 directly interact in solution and that full-length IRF3 is required for interaction with Npro. Additionally, Nprointeracts with a constitutively active form of IRF3 bound to its transcriptional cofactor, the CREB-binding protein. This is the first study to demonstrate that Nprois able to bind both inactive IRF3 monomer and activated IRF3 dimer and thus likely targets both IRF3 species for ubiquitination and proteasomal degradation.

scholarly journals Cytomegalovirus Activates Interferon Immediate-Early Response Gene Expression and an Interferon Regulatory Factor 3-Containing Interferon-Stimulated Response Element-Binding Complex

1998 ◽  
Vol 18 (7) ◽  
pp. 3796-3802 ◽  
Author(s):  
Lorena Navarro ◽  
Kerri Mowen ◽  
Steven Rodems ◽  
Brian Weaver ◽  
Nancy Reich ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Kinase Inhibitors ◽  
Nuclear Translocation ◽  
Early Response ◽  
Interferon Regulatory Factor ◽  
Immediate Early ◽  
Creb Binding Protein ◽  
Regulatory Factor ◽  
Response Element ◽  
Interferon Regulatory Factor 3

ABSTRACTInterferon establishes an antiviral state in numerous cell types through the induction of a set of immediate-early response genes. Activation of these genes is mediated by phosphorylation of latent transcription factors of the STAT family. We found that infection of primary foreskin fibroblasts with human cytomegalovirus (HCMV) causes selective transcriptional activation of the alpha/beta-interferon-responsive ISG54 gene. However, no activation or nuclear translocation of STAT proteins was detected. Activation of ISG54 occurs independent of protein synthesis but is prevented by protein tyrosine kinase inhibitors. Further analysis revealed that HCMV infection induced the DNA binding of a novel complex, tentatively called cytomegalovirus-induced interferon-stimulated response element binding factor (CIF). CIF is composed, at least in part, of the recently identified interferon regulatory factor 3 (IRF3), but it does not contain the STAT1 and STAT2 proteins that participate in the formation of interferon-stimulated gene factor 3. IRF3, which has previously been shown to possess no intrinsic transcriptional activation potential, interacts with the transcriptional coactivator CREB binding protein, but not with p300, to form CIF. Activating interferon-stimulated genes without the need for prior synthesis of interferons might provide the host cell with a potential shortcut in the activation of its antiviral defense.

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