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Simons KH, Peters HAB, Jukema JW, de Vries MR, Quax PHA. A protective role of IRF3 and IRF7 signalling downstream TLRs in the development of vein graft disease via type I interferons. J Intern Med 2017; 282:522-536. [PMID: 28857295 DOI: 10.1111/joim.12679] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Toll like receptors (TLR) play an important role in vein graft disease (VGD). Interferon regulatory factors (IRF) 3 and 7 are the transcriptional regulators of type I interferons (IFN) and type I IFN responsive genes and are downstream factors of TLRs. Relatively little is known with regard to the interplay of IRFs and TLRs in VGD development. The aim of this study was to investigate the role of IRF3 and IRF7 signaling downstream TLRs and the effect of IRF3 and IRF7 in VGD. METHODS AND RESULTS In vitro activation of TLR3 induced IRF3 and IRF7 dependent IFNβ expression in bone marrow macrophages and vascular smooth muscle cells. Activation of TLR4 showed to regulate pro-inflammatory cytokines via IRF3. Vein graft surgery was performed in Irf3-/- , Irf7-/- and control mice. After 14 days Irf3-/- vein grafts had an increased vessel wall thickness compared to both control (P = 0.01) and Irf7-/- (P = 0.02) vein grafts. After 28 days, vessel wall thickness increased in Irf3-/- (P = 0.0003) and Irf7-/- (P = 0.04) compared to control vein grafts and also increased in Irf7-/- compared to Irf3-/- vein grafts (P = 0.02). Immunohistochemical analysis showed a significant higher influx of macrophages after 14 days in Irf3-/- vein grafts and after 28 days in Irf7-/- vein grafts compared to control vein grafts. CONCLUSIONS The present study is the first to describe a protective role of both IRF3 and IRF7 in VGD. IRFs regulate VGD downstream TLRs since Irf3-/- and Irf7-/- vein grafts show increased vessel wall thickening after respectively 14 and 28 days after surgery.
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Affiliation(s)
- K H Simons
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.,Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands
| | - H A B Peters
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.,Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands
| | - J W Jukema
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - M R de Vries
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.,Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands
| | - P H A Quax
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.,Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands
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52
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Human Metapneumovirus M2-2 Protein Acts as a Negative Regulator of Alpha Interferon Production by Plasmacytoid Dendritic Cells. J Virol 2017; 91:JVI.00579-17. [PMID: 28768858 DOI: 10.1128/jvi.00579-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/24/2017] [Indexed: 12/20/2022] Open
Abstract
Human metapneumovirus (HMPV) has the ability to inhibit Toll-like receptor 7 (TLR7)- and TLR9-dependent alpha interferon (IFN-α) production by plasmacytoid dendritic cells (pDCs). However, the inhibition mechanism remains largely unknown. To identify viral proteins responsible for this inhibition, we performed a screening of HMPV open reading frames (ORFs) for the ability to block TLR7/9-dependent signaling reconstituted in HEK293T cells by transfection with myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF6), IKKα, and IFN regulatory factor 7 (IRF7). This screening demonstrated that the M2-2 protein was the most potent inhibitor of TLR7/9-dependent IFN-α induction. A recombinant HMPV in which the M2-2 ORF was silenced indeed induced greater IFN-α production by human pDCs than wild-type HMPV did. Immunoprecipitation experiments showed direct physical association of the M2-2 protein with the inhibitory domain (ID) of IRF7. As a natural consequence of this, transfection of IRF7 lacking the ID, a constitutively active mutant, resulted in activation of the IFN-α promoter even in the presence of M2-2. Bioluminescence resonance energy transfer assays and split Renilla luciferase complementation assays revealed that M2-2 inhibited MyD88/TRAF6/IKKα-induced homodimerization of IRF7. In contrast, expression of the M2-2 protein did not result in inhibition of IPS-1-induced homodimerization and resultant activation of IRF7. This indicates that inhibition of MyD88/TRAF6/IKKα-induced IRF7 homodimerization does not result from a steric effect of M2-2 binding. Instead, it was found that M2-2 inhibited MyD88/TRAF6/IKKα-induced phosphorylation of IRF7 on Ser477. These results suggest that M2-2 blocks TLR7/9-dependent IFN-α induction by preventing IRF7 homodimerization, possibly through its effects on the phosphorylation status of IRF7.IMPORTANCE The family Paramyxoviridae is divided into two subfamilies, the Paramyxovirinae and the Pneumovirinae Members of the subfamily Paramyxovirinae have the ability to inhibit TLR7/9-dependent IFN-α production, and the underlying inhibition mechanism has been intensively studied. In contrast, little is known about how members of the subfamily Pneumovirinae regulate IFN-α production by pDCs. We identified the M2-2 protein of HMPV, a member of the subfamily Pneumovirinae, as a negative regulator of IFN-α production by pDCs and uncovered the underlying mechanism. This study explains in part why the M2-2 knockout recombinant HMPV is attenuated and further suggests that M2-2 is a potential target for HMPV therapy.
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53
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Positive and Negative Regulation of Type I Interferons by the Human T Cell Leukemia Virus Antisense Protein HBZ. J Virol 2017; 91:JVI.00853-17. [PMID: 28768861 DOI: 10.1128/jvi.00853-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/14/2017] [Indexed: 01/11/2023] Open
Abstract
The pathogenesis of human T cell leukemia virus type 1 (HTLV-1) is strongly linked to the viral regulatory proteins Tax1 and HBZ, whose opposing functions contribute to the clinical outcome of infection. Type I interferons alpha and beta (IFN-α and IFN-β) are key cytokines involved in innate immunity, and IFN-α, in combination with other antivirals, is extensively used in the treatment of HTLV-1 infection. The relationship between HTLV-1 and IFN signaling is unclear, and to date the effect of HBZ on this pathway has not been examined. Here we report that HBZ significantly enhances interferon regulatory factor 7 (IRF7)-induced IFN-α- and IFN-stimulated response element (ISRE) promoter activities and IFN-α production and can counteract the inhibitory effect of Tax1. In contrast to this, we show that HBZ and Tax1 cooperate to inhibit the induction of IFN-β and ISRE promoters by IRF3 and IFN-β production. In addition, we reveal that HBZ enhances ISRE activation by IFN-α. We further show that HBZ enhances IRF7 and suppresses IRF3 activation by TBK1 and IKKε. We demonstrate that HBZ has no effect on virus-induced nuclear accumulation of IRF3, suggesting that it may inhibit IRF3 activity at a transcriptional level. We show that HBZ physically interacts with IRF7 and IKKε but not with IRF3 or TBK1. Overall, our findings suggest that both HBZ and Tax1 are negative regulators of immediate early IFN-β innate immune responses, while HBZ but not Tax1 positively regulates the induction of IFN-α and downstream IFN-α signaling.IMPORTANCE Type I interferons are powerful antiviral cytokines and are used extensively in the treatment of HTLV-1-induced adult T cell leukemia (ATL). To date, the relationship between HTLV-1 and the IFN pathway is poorly understood, and studies so far have focused on Tax1. Our study is unique in that it examined the effect of HBZ, alone or in combination with Tax1, on type I IFN signaling. This is important because HBZ is frequently the only viral protein expressed in infected cells, particularly at later stages of infection. A better understanding of the how HBZ regulates IFN signaling may lead to the development of therapeutics that can modify such responses and improve the clinical outcome for infected individuals.
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54
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Du X, Pan T, Xu J, Zhang Y, Song W, Yi Z, Yuan Z. Hepatitis C virus replicative double-stranded RNA is a potent interferon inducer that triggers interferon production through MDA5. J Gen Virol 2016; 97:2868-2882. [PMID: 27655134 DOI: 10.1099/jgv.0.000607] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The cytoplasmic RNA sensors, retinoic acid-inducible gene I and melanoma differentiation-associated gene 5, play crucial roles in innate sensing of hepatitis C virus (HCV). However, the exact identity of the IFN inducer generated during HCV infection is poorly understood. To identify the IFN inducer, we extracted the RNAs from HCV-replicating cells and introduced these into IFN signalling-competent cells to examine IFN production. RNAs isolated from HCV-replicating cells triggered robust IFN-β and IFN-λ production in Huh7 cells in a viral replication-dependent manner, preferentially through the melanoma differentiation-associated gene 5 but not through the retinoic acid-inducible gene I-mediated pathway. The IFN-inducing capacity of HCV RNA survived after calf intestinal alkaline phosphatase and ssRNA-specific S1 nuclease treatment, but was completely eliminated by dsRNA-specific RNase III digestion, suggesting that viral replicative dsRNA is an IFN inducer. Furthermore, HCV viral RNA extracted from replicating cells was sensitive to 5'-monophosphate-dependent 5'→3' exonuclease (TER) digestion, suggesting that the HCV genome lacks a 5'-triphosphate or -diphosphate. In semi-permeabilized cells, the HCV IFN inducer primarily resided in an enclosed membranous structure that protects the IFN inducer from RNase digestion. Taken together, we identified HCV replicative dsRNA as a viral IFN inducer enclosed within the viral replication factory.
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Affiliation(s)
- Xiaoting Du
- Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Tingting Pan
- Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Jun Xu
- Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Yang Zhang
- Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Wuhui Song
- Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Zhigang Yi
- Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Zhenghong Yuan
- Institute of Biomedical Sciences, Fudan University, Shanghai, PR China.,Key Laboratory of Medical Molecular Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China.,Institute of Medical Microbiology, Fudan University, Shanghai, PR China
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55
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Wang L, Zhao J, Ren J, Hall KH, Moorman JP, Yao ZQ, Ning S. Protein phosphatase 1 abrogates IRF7-mediated type I IFN response in antiviral immunity. Eur J Immunol 2016; 46:2409-2419. [PMID: 27469204 DOI: 10.1002/eji.201646491] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/12/2016] [Accepted: 07/26/2016] [Indexed: 02/04/2023]
Abstract
Interferon (IFN) regulatory factor 7 (IRF7) plays a key role in the production of IFN-α in response to viral infection, and phosphorylation at IRF7 C-terminal serine sites is prelude to its function. However, phosphatases that negatively regulate IRF7 phosphorylation and activity have not been reported. In this study, we have identified a conserved protein phosphatase 1 (PP1)-binding motif in human and mouse IRF7 proteins, and shown that PP1 physically interacts with IRF7. Exogenous expression of PP1 subunits (PP1α, β, or γ) ablates IKKε-stimulated IRF7 phosphorylation and dramatically attenuates IRF7 transcriptional activity. Inhibition of PP1 activity significantly increases IRF7 phosphorylation and IRF7-mediated IFN-α production in response to Newcastle disease virus (NDV) infection or Toll-like receptor 7 (TLR7) challenge, leading to impaired viral replication. In addition, IFN treatment, TLR challenges and viral infection induce PP1 expression. Our findings disclose for the first time a pivotal role for PP1 in impeding IRF7-mediated IFN-α production in host immune responses.
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Affiliation(s)
- Ling Wang
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.,Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA
| | - Juan Zhao
- Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA
| | - Junping Ren
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.,Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA
| | - Kenton H Hall
- Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA
| | - Jonathan P Moorman
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.,Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA.,Hepatitis (HCV/HIV) Program, James H Quillen VA Medical Center, Johnson City, TN, USA
| | - Zhi Q Yao
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA.,Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA.,Hepatitis (HCV/HIV) Program, James H Quillen VA Medical Center, Johnson City, TN, USA
| | - Shunbin Ning
- Center of Excellence for Inflammation, Infectious Diseases and Immunity, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, USA. .,Department of Internal Medicine, East Tennessee State University, Quillen College of Medicine, Johnson City, TN, USA.
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56
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Tremblay N, Baril M, Chatel-Chaix L, Es-Saad S, Park AY, Koenekoop RK, Lamarre D. Spliceosome SNRNP200 Promotes Viral RNA Sensing and IRF3 Activation of Antiviral Response. PLoS Pathog 2016; 12:e1005772. [PMID: 27454487 PMCID: PMC4959778 DOI: 10.1371/journal.ppat.1005772] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 06/27/2016] [Indexed: 12/18/2022] Open
Abstract
Spliceosomal SNRNP200 is a Ski2-like RNA helicase that is associated with retinitis pigmentosa 33 (RP33). Here we found that SNRNP200 promotes viral RNA sensing and IRF3 activation through the ability of its amino-terminal Sec63 domain (Sec63-1) to bind RNA and to interact with TBK1. We show that SNRNP200 relocalizes into TBK1-containing cytoplasmic structures upon infection, in contrast to the RP33-associated S1087L mutant, which is also unable to rescue antiviral response of SNRNP200 knockdown cells. This functional rescue correlates with the Sec63-1-mediated binding of viral RNA. The hindered IFN-β production of knockdown cells was further confirmed in peripheral blood cells of RP33 patients bearing missense mutation in SNRNP200 upon infection with Sendai virus (SeV). This work identifies a novel immunoregulatory role of the spliceosomal SNRNP200 helicase as an RNA sensor and TBK1 adaptor for the activation of IRF3-mediated antiviral innate response. The innate immune system is the first line of defense against pathogens and relies on the recognition of molecular structures specific to pathogens by sensor receptors. These receptors activate a signaling cascade and induce a protective cellular innate immune response. In this study, we provide evidence for a role of the spliceosomal SNRNP200 RNA helicase in promoting antiviral response that is clearly distinguishable of the one in pre-mRNA splicing. The depletion of SNRNP200 in human cells resulted in a reduced interferon-β (IFNB1) production and increased susceptibility to viral infection. We showed that SNRNP200 positively regulates activation of the key transcription factor IRF3 via interaction with TANK kinase 1 (TBK1). Upon infection, SNRNP200 binds viral RNA and relocalizes into TBK1-containing cytoplasmic structures to promote IRF3 activation and IFNB1 production. Of clinical relevance, we observed a significantly hindered antiviral response of PBMCs from patients carrying a dominant SNRNP200 mutation associated with retina pigmentosa type 33 (RP33), an inherited degenerative eye disease. We showed that the RP33-associated S1087L SNRNP200 mutant has lost the ability to bind RNA and that its expression fails to rescue antiviral response in SNRNP200 silenced cells. Our study provides new insights into a role within the antiviral response for spliceosome SNRNP200 helicase as an RNA sensor and TBK1 adaptor in IRF3 signaling.
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Affiliation(s)
- Nicolas Tremblay
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Canada
| | - Martin Baril
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
| | | | - Salwa Es-Saad
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
| | - Alex Young Park
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Canada
| | - Robert K. Koenekoop
- Departments of Pediatric Surgery, Human Genetics and Ophthalmology, McGill University, Montréal, Canada
| | - Daniel Lamarre
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Canada
- * E-mail:
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57
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Interferon regulatory factor 3 is a key regulation factor for inducing the expression of SAMHD1 in antiviral innate immunity. Sci Rep 2016; 6:29665. [PMID: 27411355 PMCID: PMC4944147 DOI: 10.1038/srep29665] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 06/21/2016] [Indexed: 01/07/2023] Open
Abstract
SAMHD1 is a type I interferon (IFN) inducible host innate immunity restriction factor that inhibits an early step of the viral life cycle. The underlying mechanisms of SAMHD1 transcriptional regulation remains elusive. Here, we report that inducing SAMHD1 upregulation is part of an early intrinsic immune response via TLR3 and RIG-I/MDA5 agonists that ultimately induce the nuclear translocation of the interferon regulation factor 3 (IRF3) protein. Further studies show that IRF3 plays a major role in upregulating endogenous SAMHD1 expression in a mechanism that is independent of the classical IFN-induced JAK-STAT pathway. Both overexpression and activation of IRF3 enhanced the SAMHD1 promoter luciferase activity, and activated IRF3 was necessary for upregulating SAMHD1 expression in a type I IFN cascade. We also show that the SAMHD1 promoter is a direct target of IRF3 and an IRF3 binding site is sufficient to render this promoter responsive to stimulation. Collectively, these findings indicate that upregulation of endogenous SAMHD1 expression is attributed to the phosphorylation and nuclear translocation of IRF3 and we suggest that type I IFN induction and induced SAMHD1 expression are coordinated.
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58
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Zhou Q, Lavorgna A, Bowman M, Hiscott J, Harhaj EW. Aryl Hydrocarbon Receptor Interacting Protein Targets IRF7 to Suppress Antiviral Signaling and the Induction of Type I Interferon. J Biol Chem 2015; 290:14729-39. [PMID: 25911105 DOI: 10.1074/jbc.m114.633065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Indexed: 12/25/2022] Open
Abstract
The transcription factor IRF7 (interferon regulatory factor 7) is a key regulator of type I interferon and plays essential roles in restricting virus infection and spread. IRF7 activation is tightly regulated to prevent excessive inflammation and autoimmunity; however, how IRF7 is suppressed by negative regulators remains poorly understood. Here, we have identified AIP (aryl hydrocarbon receptor interacting protein) as a new binding partner of IRF7. The interaction between AIP and IRF7 is enhanced upon virus infection, and AIP potently inhibits IRF7-induced type I IFN (IFNα/β) production. Overexpression of AIP blocks virus-induced activation of IFN, whereas knockdown of AIP by siRNA potentiates virally activated IFN production. Consistently, AIP-deficient murine embryonic fibroblasts are highly resistant to virus infection because of increased production of IFNα/β. AIP inhibits IRF7 function by antagonizing the nuclear localization of IRF7. Together, our study identifies AIP as a novel inhibitor of IRF7 and a negative regulator of innate antiviral signaling.
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Affiliation(s)
- Qinjie Zhou
- From the Department of Microbiology and Immunology, The University of Miami, Miller School of Medicine, Miami, Florida 33136
| | - Alfonso Lavorgna
- the Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Melissa Bowman
- the Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287, the Graduate Program in Cellular and Molecular Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, and
| | - John Hiscott
- the Division of Infectious Diseases, Vaccine & Gene Therapy Institute of Florida, Port Saint Lucie, Florida 34987
| | - Edward W Harhaj
- the Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21287,
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59
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Ciancanelli MJ, Huang SXL, Luthra P, Garner H, Itan Y, Volpi S, Lafaille FG, Trouillet C, Schmolke M, Albrecht RA, Israelsson E, Lim HK, Casadio M, Hermesh T, Lorenzo L, Leung LW, Pedergnana V, Boisson B, Okada S, Picard C, Ringuier B, Troussier F, Chaussabel D, Abel L, Pellier I, Notarangelo LD, García-Sastre A, Basler CF, Geissmann F, Zhang SY, Snoeck HW, Casanova JL. Infectious disease. Life-threatening influenza and impaired interferon amplification in human IRF7 deficiency. Science 2015; 348:448-53. [PMID: 25814066 DOI: 10.1126/science.aaa1578] [Citation(s) in RCA: 340] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/12/2015] [Indexed: 12/24/2022]
Abstract
Severe influenza disease strikes otherwise healthy children and remains unexplained. We report compound heterozygous null mutations in IRF7, which encodes the transcription factor interferon regulatory factor 7, in an otherwise healthy child who suffered life-threatening influenza during primary infection. In response to influenza virus, the patient's leukocytes and plasmacytoid dendritic cells produced very little type I and III interferons (IFNs). Moreover, the patient's dermal fibroblasts and induced pluripotent stem cell (iPSC)-derived pulmonary epithelial cells produced reduced amounts of type I IFN and displayed increased influenza virus replication. These findings suggest that IRF7-dependent amplification of type I and III IFNs is required for protection against primary infection by influenza virus in humans. They also show that severe influenza may result from single-gene inborn errors of immunity.
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Affiliation(s)
- Michael J Ciancanelli
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Sarah X L Huang
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, NY, USA. Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - Priya Luthra
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Hannah Garner
- Centre for Molecular and Cellular Biology of Inflammation (CMCBI), King's College London, London SE1 1UL, UK
| | - Yuval Itan
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Stefano Volpi
- Division of Immunology and Manton Center for Orphan Disease Research, Children's Hospital, Harvard Medical School, Boston, MA, USA. Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
| | - Fabien G Lafaille
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Céline Trouillet
- Centre for Molecular and Cellular Biology of Inflammation (CMCBI), King's College London, London SE1 1UL, UK
| | - Mirco Schmolke
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Randy A Albrecht
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Elisabeth Israelsson
- Department of Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Hye Kyung Lim
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Melina Casadio
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Tamar Hermesh
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Lazaro Lorenzo
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM UMR1163, Paris, France. University Paris Descartes, Imagine Institute, Paris, France
| | - Lawrence W Leung
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Vincent Pedergnana
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM UMR1163, Paris, France. University Paris Descartes, Imagine Institute, Paris, France
| | - Bertrand Boisson
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
| | - Satoshi Okada
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA. Department of Pediatrics, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
| | - Capucine Picard
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA. Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM UMR1163, Paris, France. University Paris Descartes, Imagine Institute, Paris, France. Study Centre for Primary Immunodeficiencies, AP-HP, Necker Hospital, Paris, France
| | | | | | - Damien Chaussabel
- Department of Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA. Department of Systems Biology, Sidra Medical and Research Center, Doha, Qatar
| | - Laurent Abel
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA. Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM UMR1163, Paris, France. University Paris Descartes, Imagine Institute, Paris, France
| | - Isabelle Pellier
- Pediatric Immunology, Hematology and Oncology Unit, University Hospital Centre of Angers, Angers, France. INSERM U892, CNRS U6299, Angers, France
| | - Luigi D Notarangelo
- Division of Immunology and Manton Center for Orphan Disease Research, Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Christopher F Basler
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Frédéric Geissmann
- Centre for Molecular and Cellular Biology of Inflammation (CMCBI), King's College London, London SE1 1UL, UK
| | - Shen-Ying Zhang
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA. Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM UMR1163, Paris, France. University Paris Descartes, Imagine Institute, Paris, France
| | - Hans-Willem Snoeck
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, NY, USA. Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - Jean-Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA. Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM UMR1163, Paris, France. University Paris Descartes, Imagine Institute, Paris, France. Pediatric Immuno-Hematology Unit, Necker Hospital for Sick Children, AP-HP, Paris, France. Howard Hughes Medical Institute, New York, NY, USA.
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Abstract
Recent findings unexpectedly revealed that human TLR4 can be directly activated by nickel ions. This activation is due to the coordination of nickel by a cluster of histidine residues on the ectodomain of human TLR4, which is absent in most other species. We aimed to elucidate the role of MD-2 in the molecular mechanism of TLR4/MD-2 activation by nickel, as nickel binding site on TLR4 is remote from MD-2, which directly binds the endotoxin as the main pathological activator of TLR4. We identified MD-2 and TLR4 mutants which abolished TLR4/MD-2 receptor activation by endotoxin but could nevertheless be significantly activated by nickel, which acts in synergy with LPS. Human TLR4/MD-2 was also activated by cobalt ions, while copper and cadmium were toxic in the tested concentration range. Activation of TLR4 by cobalt required MD-2 and was abolished by human TLR4 mutations of histidine residues at positions 456 and 458. We demonstrated that activation of TLR4 by nickel and cobalt ions can trigger both the MyD88-dependent and the -independent pathway. Based on our results we propose that predominantly hydrophobic interactions between MD-2 and TLR4 contribute to the stabilization of the TLR4/MD-2/metal ion complex in a conformation that enables activation.
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61
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Oblak A, Pohar J, Jerala R. MD-2 determinants of nickel and cobalt-mediated activation of human TLR4. PLoS One 2015; 10:e0120583. [PMID: 25803856 PMCID: PMC4372398 DOI: 10.1371/journal.pone.0120583] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/24/2015] [Indexed: 11/19/2022] Open
Abstract
Recent findings unexpectedly revealed that human TLR4 can be directly activated by nickel ions. This activation is due to the coordination of nickel by a cluster of histidine residues on the ectodomain of human TLR4, which is absent in most other species. We aimed to elucidate the role of MD-2 in the molecular mechanism of TLR4/MD-2 activation by nickel, as nickel binding site on TLR4 is remote from MD-2, which directly binds the endotoxin as the main pathological activator of TLR4. We identified MD-2 and TLR4 mutants which abolished TLR4/MD-2 receptor activation by endotoxin but could nevertheless be significantly activated by nickel, which acts in synergy with LPS. Human TLR4/MD-2 was also activated by cobalt ions, while copper and cadmium were toxic in the tested concentration range. Activation of TLR4 by cobalt required MD-2 and was abolished by human TLR4 mutations of histidine residues at positions 456 and 458. We demonstrated that activation of TLR4 by nickel and cobalt ions can trigger both the MyD88-dependent and the -independent pathway. Based on our results we propose that predominantly hydrophobic interactions between MD-2 and TLR4 contribute to the stabilization of the TLR4/MD-2/metal ion complex in a conformation that enables activation.
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Affiliation(s)
- Alja Oblak
- Department of Biotechnology, National institute of Chemistry, Ljubljana, Slovenia
- Centre of Excellence EN-FIST, Ljubljana, Slovenia
| | - Jelka Pohar
- Department of Biotechnology, National institute of Chemistry, Ljubljana, Slovenia
- Centre of Excellence EN-FIST, Ljubljana, Slovenia
| | - Roman Jerala
- Department of Biotechnology, National institute of Chemistry, Ljubljana, Slovenia
- Centre of Excellence EN-FIST, Ljubljana, Slovenia
- * E-mail:
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62
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Interferon regulatory factors: critical mediators of human lupus. Transl Res 2015; 165:283-95. [PMID: 25445206 PMCID: PMC4306637 DOI: 10.1016/j.trsl.2014.10.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/01/2014] [Accepted: 10/02/2014] [Indexed: 12/22/2022]
Abstract
The pathogenesis of systemic lupus erythematosus (SLE) is multifactorial, and the interferon regulatory factors (IRFs) play an important role. Autoantibodies formed in SLE target nuclear antigens, and immune complexes formed by these antibodies contain nucleic acid. These immune complexes can activate antiviral pattern recognition receptors (PRRs), resulting in the downstream activation of IRFs, which can induce type I interferon (IFN-I) and other inflammatory mediators. Genetic variations in IRFs have been associated with susceptibility to SLE, and current evidence supports the idea that these polymorphisms are gain of function in humans. Recent studies suggest that these genetic variations contribute to the break in humoral tolerance that allows for nucleic acid binding autoantibodies, and that the same polymorphisms also augment IFN-I production in the presence of these autoantibody immune complexes, forming a feed-forward loop. In this review, we will outline major features of the PRR/IRF systems and describe the role of the IRFs in human SLE pathogenesis.
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63
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Lee KJ, Ye JS, Choe H, Nam YR, Kim N, Lee U, Joo CH. Serine cluster phosphorylation liberates the C-terminal helix of IFN regulatory factor 7 to bind histone acetyltransferase p300. THE JOURNAL OF IMMUNOLOGY 2014; 193:4137-48. [PMID: 25225665 DOI: 10.4049/jimmunol.1401290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
IFN regulatory factor 7 (IRF7) is a major regulator of type I (αβ) IFN secretion. A growing body of evidence shows that IRF7 is involved in a wide variety of pathologic conditions in addition to infections; however, the detailed mechanism of IRF7 transactivation remains elusive. Our current knowledge of IRF7 transactivation is based on studies of IRF3, another major regulator of IFN-β secretion. IRF3 and IRF7 are closely related homologs with high sequence similarity in their C-terminal regions, and both proteins are activated by phosphorylation of a specific serine cluster (SC). Nevertheless, the functional domains of the two proteins are arranged in an inverted manner. We generated a model structure of the IRF7 C-terminal region using homology modeling and used it to guide subsequent functional domain studies. The model structure led to the identification of a tripod-helix structure containing the SC. Based on the model and experimental data, we hypothesized that phosphorylation-mediated IRF7 transactivation is controlled by a tripod-helix structure. Inducible IκB kinase binds a tripod-helix structure. Serial phosphorylation of the SC by the kinase liberates C-terminal helix from an inhibitory hydrophobic pocket. A histone acetyltransferase P300 binds the liberated helix. The difference in the P300 binding sites explains why the domain arrangement of IRF7 is inverted relative to that of IRF3.
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Affiliation(s)
- Kyoung Jin Lee
- Department of Microbiology, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Jung Sook Ye
- Department of Microbiology, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Han Choe
- Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul 138-736, Korea; Department of Physiology, University of Ulsan College of Medicine, Seoul 138-736, Korea; and
| | - Young Ran Nam
- Department of Microbiology, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Nari Kim
- Department of Microbiology, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Uk Lee
- Department of Microbiology, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Chul Hyun Joo
- Department of Microbiology, University of Ulsan College of Medicine, Seoul 138-736, Korea; Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul 138-736, Korea
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64
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Zhou P, Cowled C, Mansell A, Monaghan P, Green D, Wu L, Shi Z, Wang LF, Baker ML. IRF7 in the Australian black flying fox, Pteropus alecto: evidence for a unique expression pattern and functional conservation. PLoS One 2014; 9:e103875. [PMID: 25100081 PMCID: PMC4123912 DOI: 10.1371/journal.pone.0103875] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 07/02/2014] [Indexed: 12/21/2022] Open
Abstract
As the only flying mammal, bats harbor a number of emerging and re-emerging viruses, many of which cause severe diseases in humans and other mammals yet result in no clinical symptoms in bats. As the master regulator of the interferon (IFN)-dependent immune response, IFN regulatory factor 7 (IRF7) plays a central role in innate antiviral immunity. To explore the role of bat IRF7 in the regulation of the IFN response, we performed sequence and functional analysis of IRF7 from the pteropid bat, Pteropus alecto. Our results demonstrate that bat IRF7 retains the ability to bind to MyD88 and activate the IFN response despite unique changes in the MyD88 binding domain. We also demonstrate that bat IRF7 has a unique expression pattern across both immune and non-immune related tissues and is inducible by double-strand RNA. The broad tissue distribution of IRF7 may provide bats with an enhanced ability to rapidly activate the IFN response in a wider range of tissues compared to other mammals. The importance of IRF7 in antiviral activity against the bat reovirus, Pulau virus was confirmed by siRNA knockdown of IRF7 in bat cells resulting in enhanced viral replication. Our results highlight the importance of IRF7 in innate antiviral immunity in bats.
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Affiliation(s)
- Peng Zhou
- CSIRO, Australian Animal Health Laboratory, Geelong, Victoria, Australia
| | - Chris Cowled
- CSIRO, Australian Animal Health Laboratory, Geelong, Victoria, Australia
| | - Ashley Mansell
- Centre for Innate Immunity and Infectious Diseases, Monash Institute of Medical Research-Prince Henry Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Paul Monaghan
- CSIRO, Australian Animal Health Laboratory, Geelong, Victoria, Australia
| | - Diane Green
- CSIRO, Australian Animal Health Laboratory, Geelong, Victoria, Australia
| | - Lijun Wu
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Zhengli Shi
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Lin-Fa Wang
- CSIRO, Australian Animal Health Laboratory, Geelong, Victoria, Australia
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Michelle L. Baker
- CSIRO, Australian Animal Health Laboratory, Geelong, Victoria, Australia
- * E-mail:
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65
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Hu GB, Zhao MY, Lin JY, Liu QM, Zhang SC. Molecular cloning and characterization of interferon regulatory factor 9 (IRF9) in Japanese flounder, Paralichthys olivaceus. FISH & SHELLFISH IMMUNOLOGY 2014; 39:138-144. [PMID: 24837327 DOI: 10.1016/j.fsi.2014.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/10/2014] [Accepted: 05/02/2014] [Indexed: 06/03/2023]
Abstract
Interferon regulatory factor 9 (IRF9) in mammals is known to be involved in antiviral response. In this study, we studied the structure, mRNA tissue distribution and regulation of IRF9 from Japanese flounder, Paralichthys olivaceus. The cDNA sequence of IRF9 is 3305 bp long, containing an open reading frame (ORF) of 1308 bp that encodes a peptide of 435 amino acids. The predicted protein sequence shares 33.7-72.0% identity to other fish IRF9s. Japanese flounder IRF9 possesses a DNA-binding domain (DBD), an IRF association domain (IAD), two nuclear localization signals (NLSs) and a proline-rich domain (PRD). The IRF9 transcripts were detectable in all examined tissues of healthy Japanese flounders, with higher levels in the head kidney, kidney, liver and spleen. The IRF9 mRNA levels were up-regulated in the gills, head kidney, spleen and muscle when challenged with polyinosinic:polycytidylic acid (poly I:C) or lymphocystis disease virus (LCDV). The up-regulations were stronger and arose earlier in the case of poly I:C treatment in most tested organs in a 7-day time course, with maximum increases ranging from 1.37- to 8.59-fold and peak time points from 3 h to 3 d post injection depending on different organs, relative to those in the case of LCDV treatment which ranged from 1.32- to 3.21-fold and from 18 h to 3 d post injection, respectively. The highest and earliest inductions were detected in the spleen in both challenge cases, while the inductions by LCDV in the muscle were quite faint. These results demonstrate a role of Japanese flounder IRF9 in the host's antiviral responses.
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Affiliation(s)
- Guo-Bin Hu
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Ming-Yu Zhao
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Jing-Yun Lin
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Qiu-Ming Liu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Shi-Cui Zhang
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
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66
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Jakob U, Kriwacki R, Uversky VN. Conditionally and transiently disordered proteins: awakening cryptic disorder to regulate protein function. Chem Rev 2014; 114:6779-805. [PMID: 24502763 PMCID: PMC4090257 DOI: 10.1021/cr400459c] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Ursula Jakob
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048, United States
| | - Richard Kriwacki
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Vladimir N. Uversky
- Department of Molecular Medicine, University of South Florida, Tampa, Florida 33612, United States
- Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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67
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Kwa MQ, Nguyen T, Huynh J, Ramnath D, De Nardo D, Lam PY, Reynolds EC, Hamilton JA, Sweet MJ, Scholz GM. Interferon regulatory factor 6 differentially regulates Toll-like receptor 2-dependent chemokine gene expression in epithelial cells. J Biol Chem 2014; 289:19758-68. [PMID: 24872416 DOI: 10.1074/jbc.m114.584540] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Epidermal and mucosal epithelial cells are integral to host defense. They not only act as a physical barrier but also utilize pattern recognition receptors, such as the Toll-like receptors (TLRs), to detect and respond to pathogens. Members of the interferon regulatory factor (IRF) family of transcription factors are key components of TLR signaling as they impart specificity to downstream responses. Although IRF6 is a critical regulator of epithelial cell proliferation and differentiation, its role in TLR signaling has not previously been addressed. We show here that IRF6 is activated by IRAK1 as well as by MyD88 but not by TRIF or TBK1. Co-immunoprecipitation experiments further demonstrated that IRF6 can interact with IRAK1. Gene silencing in epithelial cells along with gene promoter reporter assays showed that IRAK1 mediates TLR2-inducible CCL5 gene expression at least in part by promoting IRF6 activation. Conversely, IRAK1 regulated CXCL8 gene expression independently of IRF6, thus identifying a molecular mechanism by which TLR2 signaling differentially regulates the expression of specific chemokines in epithelial cells. Bioinformatics analysis and mutagenesis-based experiments identified Ser-413 and Ser-424 as key regulatory sites in IRF6. Phosphomimetic mutation of these residues resulted in greatly enhanced IRF6 dimerization and trans-activator function. Collectively, our findings suggest that, in addition to its importance for epithelial barrier function, IRF6 also contributes to host defense by providing specificity to the regulation of inflammatory chemokine expression by TLR2 in epithelial cells.
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Affiliation(s)
- Mei Qi Kwa
- From the Oral Health Cooperative Research Centre, Melbourne Dental School, and Bio21 Institute, and Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
| | - Thao Nguyen
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
| | - Jennifer Huynh
- From the Oral Health Cooperative Research Centre, Melbourne Dental School, and Bio21 Institute, and Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
| | - Divya Ramnath
- the Institute for Molecular Bioscience, and Australian Infectious Disease Research Centre, The University of Queensland, Queensland 4072, Australia
| | - Dominic De Nardo
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
| | - Pui Yeng Lam
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
| | - Eric C Reynolds
- From the Oral Health Cooperative Research Centre, Melbourne Dental School, and Bio21 Institute, and
| | - John A Hamilton
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
| | - Matthew J Sweet
- the Institute for Molecular Bioscience, and Australian Infectious Disease Research Centre, The University of Queensland, Queensland 4072, Australia
| | - Glen M Scholz
- From the Oral Health Cooperative Research Centre, Melbourne Dental School, and Bio21 Institute, and Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Victoria 3010, Australia, and
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68
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MicroRNA 155 regulates Japanese encephalitis virus-induced inflammatory response by targeting Src homology 2-containing inositol phosphatase 1. J Virol 2014; 88:4798-810. [PMID: 24522920 DOI: 10.1128/jvi.02979-13] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED MicroRNAs (miRNAs) are single-stranded small RNA molecules that regulate various cellular processes. miRNA 155 (miR-155) regulates various aspects of innate and adaptive immune responses and plays a key role in various viral infections and the resulting neuroinflammation. The present study evaluated the involvement of miR-155 in modulating Japanese encephalitis virus (JEV)-induced neuroinflammation. We observed that miR-155 expression was upregulated during JEV infection of mouse primary microglia, the BV-2 microglia cell line, and in both mouse and human brains. In vitro and in vivo knockdown of miR-155 minimized JEV-induced inflammatory responses. In the present study, we confirmed targeting of the Src homology 2-containing inositol phosphatase 1 (SHIP1) 3' untranslated region (UTR) by miR-155 in the context of JEV infection. Inhibition of SHIP1 by miR-155 resulted in higher beta interferon (IFN-β) and proinflammatory cytokine production through activation of TANK-binding kinase 1 (TBK-1). Based on these observations, we conclude that miR-155 modulates the neuroinflammatory response during JEV infection via negative regulation of SHIP1 expression. Thus, modulation of miR-155 could be a novel strategy to regulate JEV-induced neuroinflammation. IMPORTANCE Japanese encephalitis virus (JEV), a member of the family Flaviviridae that causes Japanese encephalitis (JE), is the most common mosquito-borne encephalitis virus in the Asia-Pacific region. The disease is feared, as currently there are no specific antiviral drugs available. JEV targets the central nervous system, leading to high mortality and neurological and psychiatric sequelae in some of those who survive. The level of inflammation correlates well with the clinical outcome in patients. Recently, microRNA (miRNA), a single-stranded noncoding RNA, has been implicated in various brain disorders. The present study investigates the role of miRNA in JEV-induced neuroinflammation. Our results show that miRNA 155 (miR-155) targets the Src homology 2-containing inositol phosphatase 1 (SHIP1) protein and promotes inflammation by regulating the NF-κB pathway, increasing the expression of various proinflammatory cytokines and the antiviral response. Thus, miR-155 is a potential therapeutic target to develop antivirals in JE and other brain disorders where inflammation plays a significant role in disease progression.
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69
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Rustagi A, Gale M. Innate antiviral immune signaling, viral evasion and modulation by HIV-1. J Mol Biol 2013; 426:1161-77. [PMID: 24326250 DOI: 10.1016/j.jmb.2013.12.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/26/2013] [Accepted: 12/02/2013] [Indexed: 02/08/2023]
Abstract
The intracellular innate antiviral response in human cells is an essential component of immunity against virus infection. As obligate intracellular parasites, all viruses must evade the actions of the host cell's innate immune response in order to replicate and persist. Innate immunity is induced when pathogen recognition receptors of the host cell sense viral products including nucleic acid as "non-self". This process induces downstream signaling through adaptor proteins to activate latent transcription factors that drive the expression of genes encoding antiviral and immune modulatory effector proteins that restrict virus replication and regulate adaptive immunity. The interferon regulatory factors (IRFs) are transcription factors that play major roles in innate immunity. In particular, IRF3 is activated in response to infection by a range of viruses including RNA viruses, DNA viruses and retroviruses. Among these viruses, human immunodeficiency virus type 1 (HIV-1) remains a major global health problem mediating chronic infection in millions of people wherein recent studies show that viral persistence is linked with the ability of the virus to dysregulate and evade the innate immune response. In this review, we discuss viral pathogen sensing, innate immune signaling pathways and effectors that respond to viral infection, the role of IRF3 in these processes and how it is regulated by pathogenic viruses. We present a contemporary overview of the interplay between HIV-1 and innate immunity, with a focus on understanding how innate immune control impacts infection outcome and disease.
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Affiliation(s)
- Arjun Rustagi
- Departments of Immunology and Global Health, University of Washington, Seattle, WA 98195-8059, USA
| | - Michael Gale
- Departments of Immunology and Global Health, University of Washington, Seattle, WA 98195-8059, USA.
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70
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Schmid S, Sachs D, tenOever BR. Mitogen-activated protein kinase-mediated licensing of interferon regulatory factor 3/7 reinforces the cell response to virus. J Biol Chem 2013; 289:299-311. [PMID: 24275658 DOI: 10.1074/jbc.m113.519934] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The induction of the intrinsic antiviral defense in mammals relies on the accumulation of foreign genetic material. As such, complete engagement of this response is limited to replication-competent viruses. Interferon regulatory factors (IRFs) are mediators of this defense with shared enhancer elements but display a spectrum of transcriptional potential. Here we describe a mechanism designed to enhance this response should a pathogen not be successfully inhibited. We find that activation of IRF7 results in the induction of MAP3K8 and restructuring of the antiviral transcriptome. MAP3K8 mediates the phosphorylation and repression of IRF3 homodimers to promote greater transcriptional activity through utilization of IRF3:IRF7 heterodimers. Among the genes influenced by the MAP3K8/IRF7 signaling axis are members of the SP100 gene family that serve as general transcriptional enhancers of the antiviral defense. We propose that this feed forward loop serves to reinforce the cellular response and is reserved for imminent threats to the host.
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71
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Perrotti E, Marsili G, Sgarbanti M, Remoli AL, Fragale A, Acchioni C, Orsatti R, Battistini A. IRF-7: an antiviral factor and beyond. Future Virol 2013. [DOI: 10.2217/fvl.13.88] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This review will summarize main characteristics and functions of IRF-7. IRF-7 and the highly homologous IRF-3 are two members of the IRF family of transcription factors that have emerged as crucial regulators of type I interferon (IFN) in response to pathogenic infections downstream pathogen recognition receptors. IRF-7 is also part of a positive-feedback regulatory loop essential for sustained IFN responses. Thus, tight regulation of its expression and activity is necessary to balance IFN-mediated beneficial effects and unwanted pathological consequences of IFN overproduction. Its role as an antiviral factor independent of IFN expression, and its involvement in other cellular functions beyond antiviral functions, including regulation of oncogenesis and metabolism, underscore its important role in the regulation of cellular homeostasis.
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Affiliation(s)
- Edvige Perrotti
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Giulia Marsili
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Marco Sgarbanti
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Anna Lisa Remoli
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Alessandra Fragale
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Chiara Acchioni
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Roberto Orsatti
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Angela Battistini
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
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72
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Bosinger SE, Johnson ZP, Folkner KA, Patel N, Hashempour T, Jochems SP, del Rio Estrada PM, Paiardini M, Lin R, Vanderford TH, Hiscott J, Silvestri G. Intact type I Interferon production and IRF7 function in sooty mangabeys. PLoS Pathog 2013; 9:e1003597. [PMID: 24009514 PMCID: PMC3757038 DOI: 10.1371/journal.ppat.1003597] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 07/20/2013] [Indexed: 11/19/2022] Open
Abstract
In contrast to pathogenic HIV/SIV infections of humans and rhesus macaques (RMs), natural SIV infection of sooty mangabeys (SMs) is typically non-pathogenic despite high viremia. Several studies suggested that low immune activation and relative resistance of CD4+ central memory T-cells from virus infection are mechanisms that protect SMs from AIDS. In 2008 it was reported that plasmacytoid dendritic cells (pDCs) of SMs exhibit attenuated interferon-alpha (IFN-α) responses to TLR7/9 ligands in vitro, and that species-specific amino acid substitutions in SM Interferon Regulatory Factor-7 (IRF7) are responsible for this observation. Based on these findings, these authors proposed that "muted" IFN-α responses are responsible for the benign nature of SIV infection in SMs. However, other studies indicated that acutely SIV-infected SMs show robust IFN-α responses and marked upregulation of Interferon Stimulated Genes (ISGs). To investigate this apparent disparity, we first examined the role of the reported IRF7 amino acid substitutions in SMs. To this end, we sequenced all IRF7 exons in 16 breeders, and exons displaying variability (exons 2,3,5,6,7,8) in the remainder of the colony (177 animals). We found that the reported Ser-Gly substitution at position 191 was a sequencing error, and that several of the remaining substitutions represent only minor alleles. In addition, functional assays using recombinant SM IRF7 showed no defect in its ability to translocate in the nucleus and drive transcription from an IFN-α promoter. Furthermore, in vitro stimulation of SM peripheral blood mononuclear cells with either the TLR7 agonist CL097 or SIV(mac239) induced an 500-800-fold induction of IFN-α and IFN-β mRNA, and levels of IFN-α production by pDCs similar to those of RMs or humans. These data establish that IFN-α and IRF7 signaling in SMs are largely intact, with differences with RMs that are minor and unlikely to play any role in the AIDS resistance of SIV-infected SMs.
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Affiliation(s)
- Steven E. Bosinger
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
- Non-Human Primate Genomics Core, Yerkes National Primate Research Center, Robert W. Woodruff Health Sciences Center, Emory University, Atlanta, Georgia, United States of America
| | - Zachary P. Johnson
- Non-Human Primate Genomics Core, Yerkes National Primate Research Center, Robert W. Woodruff Health Sciences Center, Emory University, Atlanta, Georgia, United States of America
- Division of Cognitive and Developmental Biology, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - Kathryn A. Folkner
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - Nirav Patel
- Non-Human Primate Genomics Core, Yerkes National Primate Research Center, Robert W. Woodruff Health Sciences Center, Emory University, Atlanta, Georgia, United States of America
| | - Tayebeh Hashempour
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - Simon P. Jochems
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - Perla M. del Rio Estrada
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - Mirko Paiardini
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - Rongtuan Lin
- Lady Davis Institute-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Thomas H. Vanderford
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
| | - John Hiscott
- Lady Davis Institute-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
- Vaccine and Gene Therapy Institute of Florida Port Saint Lucie, Florida, United States of America
| | - Guido Silvestri
- Divison of Microbiology and Immunology, Emory Vaccine Center, Yerkes National Primate Research Center, Atlanta, Georgia, United States of America
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Wang J, Yang B, Hu Y, Zheng Y, Zhou H, Wang Y, Ma Y, Mao K, Yang L, Lin G, Ji Y, Wu X, Sun B. Negative regulation of Nmi on virus-triggered type I IFN production by targeting IRF7. THE JOURNAL OF IMMUNOLOGY 2013; 191:3393-9. [PMID: 23956435 DOI: 10.4049/jimmunol.1300740] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Viral infection causes host cells to produce type I IFNs, which play a critical role in viral clearance. IFN regulatory factor (IRF) 7 is the master regulator of type I IFN-dependent immune responses. In this article, we report that N-Myc and STATs interactor (Nmi), a Sendai virus-inducible protein, interacted with IRF7 and inhibited virus-triggered type I IFN production. The overexpression of Nmi inhibited the Sendai virus-triggered induction of type I IFNs, whereas the knockdown of Nmi promoted IFN production. Furthermore, the enhanced production of IFNs resulting from Nmi knockdown was sufficient to protect cells from infection by vesicular stomatitis virus. In addition, Nmi was found to promote the K48-linked ubiquitination of IRF7 and the proteasome-dependent degradation of this protein. Finally, an impairment of antiviral responses is also detectable in Nmi-transgenic mice. These findings suggest that Nmi is a negative regulator of the virus-triggered induction of type I IFNs that targets IRF7.
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Affiliation(s)
- Jie Wang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
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74
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Ersing I, Bernhardt K, Gewurz BE. NF-κB and IRF7 pathway activation by Epstein-Barr virus Latent Membrane Protein 1. Viruses 2013; 5:1587-606. [PMID: 23793113 PMCID: PMC3717723 DOI: 10.3390/v5061587] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 06/17/2013] [Accepted: 06/18/2013] [Indexed: 12/22/2022] Open
Abstract
The principal Epstein-Barr virus (EBV) oncoprotein, Latent Membrane Protein 1 (LMP1), is expressed in most EBV-associated human malignancies. LMP1 mimics CD40 receptor signaling to provide infected cells with constitutive NF-κB, MAP kinase, IRF7, and PI3 kinase pathway stimulation. EBV-transformed B-cells are particularly dependent on constitutive NF-κB activity, and rapidly undergo apoptosis upon NF-κB blockade. Here, we review LMP1 function, with special attention to current understanding of the molecular mechanisms of LMP1-mediated NF-κB and IRF7 pathway activation. Recent advances include the elucidation of transmembrane motifs important for LMP1 trafficking and ligand-independent signaling, analysis of genome-wide LMP1 gene targets, and the identification of novel cell proteins that mediate LMP1 NF-κB and IRF7 pathway activation.
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Affiliation(s)
| | | | - Benjamin E. Gewurz
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-011-617-525-4263; Fax: +1-011-615-525-4251
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75
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Baril M, Es-Saad S, Chatel-Chaix L, Fink K, Pham T, Raymond VA, Audette K, Guenier AS, Duchaine J, Servant M, Bilodeau M, Cohen É, Grandvaux N, Lamarre D. Genome-wide RNAi screen reveals a new role of a WNT/CTNNB1 signaling pathway as negative regulator of virus-induced innate immune responses. PLoS Pathog 2013; 9:e1003416. [PMID: 23785285 PMCID: PMC3681753 DOI: 10.1371/journal.ppat.1003416] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/26/2013] [Indexed: 12/24/2022] Open
Abstract
To identify new regulators of antiviral innate immunity, we completed the first genome-wide gene silencing screen assessing the transcriptional response at the interferon-β (IFNB1) promoter following Sendai virus (SeV) infection. We now report a novel link between WNT signaling pathway and the modulation of retinoic acid-inducible gene I (RIG-I)-like receptor (RLR)-dependent innate immune responses. Here we show that secretion of WNT2B and WNT9B and stabilization of β-catenin (CTNNB1) upon virus infection negatively regulate expression of representative inducible genes IFNB1, IFIT1 and TNF in a CTNNB1-dependent effector mechanism. The antiviral response is drastically reduced by glycogen synthase kinase 3 (GSK3) inhibitors but restored in CTNNB1 knockdown cells. The findings confirm a novel regulation of antiviral innate immunity by a canonical-like WNT/CTNNB1 signaling pathway. The study identifies novel avenues for broad-spectrum antiviral targets and preventing immune-mediated diseases upon viral infection.
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Affiliation(s)
- Martin Baril
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Salwa Es-Saad
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Laurent Chatel-Chaix
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Karin Fink
- Centre de Recherche du CHUM (CRCHUM), Hôpital Saint-Luc, Montréal, Québec, Canada
| | - Tram Pham
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Valérie-Ann Raymond
- Centre de Recherche du CHUM (CRCHUM), Hôpital Saint-Luc, Montréal, Québec, Canada
| | - Karine Audette
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Anne-Sophie Guenier
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Jean Duchaine
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Marc Servant
- Faculté de Pharmacie, Université de Montréal, Montréal, Québec, Canada
| | - Marc Bilodeau
- Centre de Recherche du CHUM (CRCHUM), Hôpital Saint-Luc, Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
| | - Éric Cohen
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Nathalie Grandvaux
- Centre de Recherche du CHUM (CRCHUM), Hôpital Saint-Luc, Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
| | - Daniel Lamarre
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
- Centre de Recherche du CHUM (CRCHUM), Hôpital Saint-Luc, Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
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76
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Human parainfluenza virus type 2 V protein inhibits TRAF6-mediated ubiquitination of IRF7 to prevent TLR7- and TLR9-dependent interferon induction. J Virol 2013; 87:7966-76. [PMID: 23678181 DOI: 10.1128/jvi.03525-12] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Paramyxovirus V proteins block Toll-like receptor 7 (TLR7)- and TLR9-dependent signaling leading to alpha interferon production. Our recent study has provided evidence that interaction of the V proteins with IRF7 is important for the blockade. However, the detailed mechanisms still remain unclear. Here we reexamined the interaction of the human parainfluenza virus type 2 (HPIV2) V protein with signaling molecules involved in TLR7/9-dependent signaling. Immunoprecipitation experiments in HEK293T cells transfected with V protein and one of the signaling molecules revealed that the V protein interacted with not only IRF7 but also TRAF6, IKKα, and MyD88. Whereas overexpression of TRAF6 markedly enhanced the level of V protein associating with IRF7, IKKα, and MyD88 in HEK293T cells, the level of V protein associating with TRAF6 was little affected by overexpression of IRF7, IKKα, and MyD88. Moreover, knockdown or knockout of endogenous TRAF6 in HEK293T or mouse embryonic fibroblast cells resulted in dissociation of the V protein from IRF7, IKKα, and MyD88. These results demonstrate that binding of the V protein to IRF7, IKKα, and MyD88 is largely indirect and mediated by endogenous TRAF6. It was found that the V protein inhibited TRAF6-mediated lysine 63 (K63)-linked polyubiquitination of IRF7, which is prerequisite for IRF7 activation. Disruption of the tryptophan-rich motif of the V protein significantly affected its TRAF6-binding efficiency, which correlated well with the magnitude of inhibition of K63-linked polyubiquitination and the resultant activation of IRF7. Taken together, these results suggest that the HPIV2 V protein prevents TLR7/9-dependent interferon induction by inhibiting TRAF6-mediated K63-linked polyubiquitination of IRF7.
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77
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Marion JD, Roberts CF, Call RJ, Forbes JL, Nelson KT, Bell JE, Bell JK. Mechanism of endogenous regulation of the type I interferon response by suppressor of IκB kinase epsilon (SIKE), a novel substrate of TANK-binding kinase 1 (TBK1). J Biol Chem 2013; 288:18612-23. [PMID: 23649622 DOI: 10.1074/jbc.m112.440859] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
TANK-binding kinase 1 (TBK1) serves as a key convergence point in multiple innate immune signaling pathways. In response to receptor-mediated pathogen detection, TBK1 phosphorylation promotes production of pro-inflammatory cytokines and type I interferons. Increasingly, TBK1 dysregulation has been linked to autoimmune disorders and cancers, heightening the need to understand the regulatory controls of TBK1 activity. Here, we describe the mechanism by which suppressor of IKKε (SIKE) inhibits TBK1-mediated phosphorylation of interferon regulatory factor 3 (IRF3), which is essential to type I interferon production. Kinetic analyses showed that SIKE not only inhibits IRF3 phosphorylation but is also a high affinity TBK1 substrate. With respect to IRF3 phosphorylation, SIKE functioned as a mixed-type inhibitor (K(i, app) = 350 nM) rather than, given its status as a TBK1 substrate, as a competitive inhibitor. TBK1 phosphorylation of IRF3 and SIKE displayed negative cooperativity. Both substrates shared a similar Km value at low substrate concentrations (∼50 nM) but deviated >8-fold at higher substrate concentrations (IRF3 = 3.5 μM; SIKE = 0.4 μM). TBK1-SIKE interactions were modulated by SIKE phosphorylation, clustered in the C-terminal portion of SIKE (Ser-133, -185, -187, -188, -190, and -198). These sites exhibited striking homology to the phosphorylation motif of IRF3. Mutagenic probing revealed that phosphorylation of Ser-185 controlled TBK1-SIKE interactions. Taken together, our studies demonstrate for the first time that SIKE functions as a TBK1 substrate and inhibits TBK1-mediated IRF3 phosphorylation by forming a high affinity TBK1-SIKE complex. These findings provide key insights into the endogenous control of a critical catalytic hub that is achieved not by direct repression of activity but by redirection of catalysis through substrate affinity.
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Affiliation(s)
- James D Marion
- Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, USA
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78
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The microRNA miR-155 controls CD8(+) T cell responses by regulating interferon signaling. Nat Immunol 2013; 14:593-602. [PMID: 23603793 PMCID: PMC3664306 DOI: 10.1038/ni.2576] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 02/26/2013] [Indexed: 02/07/2023]
Abstract
We found upregulation of expression of the microRNA miR-155 in primary effector and effector memory CD8(+) T cells, but low miR-155 expression in naive and central memory cells. Antiviral CD8(+) T cell responses and viral clearance were impaired in miR-155-deficient mice, and this defect was intrinsic to CD8(+) T cells, as miR-155-deficient CD8(+) T cells mounted greatly diminished primary and memory responses. Conversely, miR-155 overexpression augmented antiviral CD8(+) T cell responses in vivo. Gene-expression profiling showed that miR-155-deficient CD8(+) T cells had enhanced type I interferon signaling and were more susceptible to interferon's antiproliferative effect. Inhibition of the type I interferon-associated transcription factors STAT1 or IRF7 resulted in enhanced responses of miR-155-deficient CD8(+) T cells in vivo. We have thus identified a previously unknown role for miR-155 in regulating responsiveness to interferon and CD8(+) T cell responses to pathogens in vivo.
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79
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Hew K, Dahlroth SL, Venkatachalam R, Nasertorabi F, Lim BT, Cornvik T, Nordlund P. The crystal structure of the DNA-binding domain of vIRF-1 from the oncogenic KSHV reveals a conserved fold for DNA binding and reinforces its role as a transcription factor. Nucleic Acids Res 2013; 41:4295-306. [PMID: 23435230 PMCID: PMC3627575 DOI: 10.1093/nar/gkt082] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus encodes four viral homologues to cellular interferon regulatory factors (IRFs), where the most studied is vIRF-1. Even though vIRF-1 shows sequence homology to the N-terminal DNA-binding domain (DBD) of human IRFs, a specific role for this domain in vIRF-1’s function has remained uncertain. To provide insights into the function of the vIRF-1 DBD, we have determined the crystal structure of it in complex with DNA and in its apo-form. Using a thermal stability shift assay (TSSA), we show that the vIRF-1 DBD binds DNA, whereas full-length vIRF-1 does not, suggesting a cis-acting regulatory mechanism in similarity to human IRFs. The complex structure of vIRF-1 DBD reveals interactions with the DNA backbone and the positioning of two arginines for specific recognition in the major grove. A superimposition with human IRF-3 reveals a similar positioning of the two specificity-determining arginines, and additional TSSAs indicate binding of vIRF-1 to an IRF-3 operator consensus sequence. The results from this study, therefore, provide support that vIRF-1 has evolved to bind DNA and plays a role in DNA binding in the context of transcriptional regulation and might act on some of the many operator sequences controlled by human IRF-3.
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Affiliation(s)
- Kelly Hew
- Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
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80
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Epstein-Barr virus latent membrane protein 1 regulates the function of interferon regulatory factor 7 by inducing its sumoylation. J Virol 2012; 86:12251-61. [PMID: 22951831 DOI: 10.1128/jvi.01407-12] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) induces multiple signal transduction pathways during latent EBV infection via its C-terminal activating region 1 (CTAR1), CTAR2, and the less-studied CTAR3. One mechanism by which LMP1 regulates cellular activation is through the induction of protein posttranslational modifications, including phosphorylation and ubiquitination. We recently documented that LMP1 induces a third major protein modification by physically interacting with the SUMO-conjugating enzyme Ubc9 through CTAR3 and inducing the sumoylation of cellular proteins in latently infected cells. We have now identified a specific target of LMP1-induced sumoylation, interferon regulatory factor 7 (IRF7). We hypothesize that during EBV latency, LMP1 induces the sumoylation of IRF7, limiting its transcriptional activity and modulating the activation of innate immune responses. Our data show that endogenously sumoylated IRF7 is detected in latently infected EBV lymphoblastoid cell lines. LMP1 expression coincided with increased sumoylation of IRF7 in a CTAR3-dependent manner. Additional experiments show that LMP1 CTAR3-induced sumoylation regulates the expression and function of IRF7 by decreasing its turnover, increasing its nuclear retention, decreasing its DNA binding, and limiting its transcriptional activation. Finally, we identified that IRF7 is sumoylated at lysine 452. These data demonstrate that LMP1 CTAR3 does in fact function in intracellular signaling, leading to biologic effects. We propose that CTAR3 is an important signaling region of LMP1 that regulates protein function by sumoylation. We have shown specifically that LMP1 CTAR3, in cooperation with CTAR2, can limit the ability of IRF7 to induce innate immune responses by inducing the sumoylation of IRF7.
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81
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Shi J, Zhang YB, Liu TK, Sun F, Gui JF. Subcellular localization and functional characterization of a fish IRF9 from crucian carp Carassius auratus. FISH & SHELLFISH IMMUNOLOGY 2012; 33:258-266. [PMID: 22626811 DOI: 10.1016/j.fsi.2012.05.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 04/19/2012] [Accepted: 05/07/2012] [Indexed: 06/01/2023]
Abstract
Mammalian interferon (IFN) regulatory factor 9 (IRF-9) has long been recognized as the DNA sequence recognition subunit of IFN-stimulated gene factor 3 (ISGF3) complex, which is critical for type I IFN to induce the expression of IFN-stimulated genes (ISGs) against viral infection. Recent studies have shown that fish IFN exerts antiviral effects by induction of a number of ISGs and also of itself; however, little is known about the role of fish IRF9 in IFN signaling. Here we identify a fish IRF9 orthologue (CaIRF9) from IFN-producing cell line, crucian carp Carassius auratus blastulae embryonic (CAB) cells. Analysis of subcellular distribution of CaIRF9-green fluorescent protein indicates that CaIRF9 is constitutively present in the nucleus, which is driven by two nuclear localization signals (NLS), one locating within DNA-binding domain (DBD) of CaIRF9 and the other immediately behind DBD, although human IRF9 contains only one NLS analogous to the former of CaIRF9. Overexpression of CaIRF9 together with CaSTAT2 not only activates ISRE-containing promoter but also upregulates the expression of fish ISGs. Strikingly, CaIRF9 together with CaSTAT2 also exhibits an ability to activate crucian carp IFN promoter, and blockade of cellular CaIRF9 attenuates IFN itself-induced activation of crucian carp IFN promoter. Taken together, these data suggest that crucian carp IFN induces the expression of ISGs and also of itself possibly by the JAK-STAT signaling pathway that is conserved from fish to mammals.
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Affiliation(s)
- Jun Shi
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Wuhan, China
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82
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ORF45 of Kaposi's sarcoma-associated herpesvirus inhibits phosphorylation of interferon regulatory factor 7 by IKKε and TBK1 as an alternative substrate. J Virol 2012; 86:10162-72. [PMID: 22787218 DOI: 10.1128/jvi.05224-11] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Open reading frame 45 (ORF45) of Kaposi's sarcoma-associated herpesvirus (KSHV) is an immediate-early and tegument protein that plays critical roles in antagonizing host antiviral responses. We have previously shown (Zhu et al, Proc. Natl. Acad. Sci. U. S. A., 99:5573-5578, 2002) that ORF45 suppresses activation of interferon regulatory factor 7 (IRF7), a crucial regulator of type I interferon gene expression, by blocking its virus-induced phosphorylation and nuclear accumulation. We report here further characterization of the mechanisms by which ORF45 inhibits IRF7 phosphorylation. In most cell types, IRF7 is phosphorylated and activated by IKKε and TBK1 after viral infection. We found that phosphorylation of IRF7 on Ser477 and Ser479 by IKKε or TBK1 is inhibited by ORF45. The inhibition is specific to IRF7 because phosphorylation of its close relative IRF3 is not affected by ORF45, implying that ORF45 does not inactivate the kinases directly. In fact, we found that ORF45 is phosphorylated efficiently on Ser41 and Ser162 by IKKε and TBK1. We demonstrated that ORF45 competes with the associated IRF7 and inhibits its phosphorylation by IKKε or TBK1 by acting as an alternative substrate.
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83
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Yue X, Wang H, Zhao F, Liu S, Wu J, Ren W, Zhu Y. Hepatitis B Virus-Induced Calreticulin Protein Is Involved in IFN Resistance. THE JOURNAL OF IMMUNOLOGY 2012; 189:279-86. [DOI: 10.4049/jimmunol.1103405] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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84
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Chang Foreman HC, Van Scoy S, Cheng TF, Reich NC. Activation of interferon regulatory factor 5 by site specific phosphorylation. PLoS One 2012; 7:e33098. [PMID: 22412986 PMCID: PMC3297630 DOI: 10.1371/journal.pone.0033098] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 02/09/2012] [Indexed: 12/17/2022] Open
Abstract
The cellular defense to infection depends on accurate activation of transcription factors and expression of select innate immunity genes. Interferon regulatory factor 5 (IRF5), a risk factor for systemic lupus erythematosus, is activated in response to pathogen recognition receptor engagement and downstream effector molecules. We find the nucleotide-binding oligomerization domain containing protein 2 (NOD2) receptor to be a significant activator of IRF5. Phosphorylation is key to the regulation of IRF5, but the precise phosphorylation sites in IRF5 remained to be identified. We used mass spectrometry to identify for the first time specific residues that are phosphorylated in response to TANK-binding kinase-1 (TBK-1), tumor necrosis factor receptor-associated factor 6 (TRAF6), or receptor interacting protein 2 (RIP2). RIP2, a kinase known to function downstream of NOD2, was the most effective activator of IRF5-regulated gene expression. To determine if the phosphorylated residues are required or sufficient for IRF5 activity, aspartic acid phosphomimetic substitutions or inactivating alanine substitutions were tested. Phosphorylation of carboxyl serines 451 and 462 appear the primary trigger of IRF5 function in nuclear accumulation, transcription, and apoptosis. Results indicate polyubiquitination of IRF5 does not play a major role in its transcriptional activity, and that ubiquitination and phosphorylation are independent modifications.
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Affiliation(s)
| | | | | | - Nancy C. Reich
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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85
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A20 (Tnfaip3) deficiency in myeloid cells protects against influenza A virus infection. PLoS Pathog 2012; 8:e1002570. [PMID: 22396652 PMCID: PMC3291650 DOI: 10.1371/journal.ppat.1002570] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 01/24/2012] [Indexed: 12/12/2022] Open
Abstract
The innate immune response provides the first line of defense against viruses and other pathogens by responding to specific microbial molecules. Influenza A virus (IAV) produces double-stranded RNA as an intermediate during the replication life cycle, which activates the intracellular pathogen recognition receptor RIG-I and induces the production of proinflammatory cytokines and antiviral interferon. Understanding the mechanisms that regulate innate immune responses to IAV and other viruses is of key importance to develop novel therapeutic strategies. Here we used myeloid cell specific A20 knockout mice to examine the role of the ubiquitin-editing protein A20 in the response of myeloid cells to IAV infection. A20 deficient macrophages were hyperresponsive to double stranded RNA and IAV infection, as illustrated by enhanced NF-κB and IRF3 activation, concomitant with increased production of proinflammatory cytokines, chemokines and type I interferon. In vivo this was associated with an increased number of alveolar macrophages and neutrophils in the lungs of IAV infected mice. Surprisingly, myeloid cell specific A20 knockout mice are protected against lethal IAV infection. These results challenge the general belief that an excessive host proinflammatory response is associated with IAV-induced lethality, and suggest that under certain conditions inhibition of A20 might be of interest in the management of IAV infections. Influenza virus or flu epidemics represent a recurrent threat to the public health, especially for individuals which are part of a high-risk group such as children, elderly or immune-compromised people. Sporadic pandemic flu outbreaks, such as the Spanish flu of 1918, may cause high grades of mortality among healthy persons. A better understanding of how the immune system deals with these pathogens is of key importance. The protein A20 is an important negative regulator of both innate and adaptive immune responses. We show that the specific deletion of A20 in myeloid cells, such as macrophages and neutrophils, improves the resistance against otherwise lethal influenza infections. This protective effect is mediated by an enhanced innate immune response following respiratory challenge with influenza virus. Although exaggerated pulmonary immune responses are believed to be the primary cause of often life threatening influenza virus induced pneumonia, we demonstrate that boosting the innate immune response by selectively targeting the functionality of A20 in myeloid cells is beneficial for the host survival. This finding provides us with a novel valuable approach for treating influenza and potentially other respiratory viral infections.
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86
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Virus-activated interferon regulatory factor 7 upregulates expression of the interferon-regulated BST2 gene independently of interferon signaling. J Virol 2012; 86:3513-27. [PMID: 22301143 DOI: 10.1128/jvi.06971-11] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BST-2/tetherin is an interferon (IFN)-inducible host restriction factor that inhibits the release of many enveloped viruses and functions as a negative-feedback regulator of IFN production by plasmacytoid dendritic cells. Currently, mechanisms underlying BST2 transcriptional regulation by type I IFN remain largely unknown. Here, we demonstrate that the BST2 promoter is a secondary target of the IFN cascade and show that a single IRF binding site is sufficient to render this promoter responsive to IFN-α. Interestingly, expression of IRF-1 or virus-activated forms of IRF-3 and IRF-7 stimulated the BST2 promoter even under conditions where type I IFN signaling was inhibited. Indeed, vesicular stomatitis virus could directly upregulate BST-2 during infection of mouse embryonic fibroblasts through a process that required IRF-7 but was independent from the type I IFN cascade; however, in order to achieve optimal BST-2 induction, the type I IFN cascade needed to be engaged through activation of IRF-3. Furthermore, using human peripheral blood mononuclear cells, we show that BST-2 upregulation is part of an early intrinsic immune response since TLR8 and TLR3 agonists, known to trigger pathways that mediate activation of IRF proteins, could upregulate BST-2 prior to engagement of the type I IFN pathway. Collectively, our findings reveal that BST2 is activated by the same signals that trigger type I IFN production, outlining a regulatory mechanism ensuring that production of type I IFN and expression of a host restriction factor involved in the IFN negative-feedback loop are closely coordinated.
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Contribution of a TANK-binding kinase 1-interferon (IFN) regulatory factor 7 pathway to IFN-γ-induced gene expression. Mol Cell Biol 2012; 32:1032-43. [PMID: 22252317 DOI: 10.1128/mcb.06021-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Signal transducers and activators of transcription (STATs) and interferon regulatory factors (IRFs) share common target genes. Here we show that the Irf7 gene is regulated by transcription factors STAT1 and IRF9 in response to the type II interferon (IFN) IFN-γ. IRF7 cooperated with STAT1 and IRF1 to stimulate the expression of a subset of IFN-γ-induced STAT1 target genes. IRF7-mediated control of the Gbp2 gene required the presence and basal activity of the S/T kinase TANK-binding kinase 1 (TBK1), whereas the binding of IRF7 to the Gbp2 promoter did not. Analysis of RNA polymerase II (Pol II) recruitment to the Gbp2 promoter revealed a role for IRF7 at later stages of the IFN-γ response. In support of the role of IRF7 in establishing an effective antibacterial response, IFN-γ-pretreated Irf7(-/-) macrophages showed an increased bacterial burden after infection with Listeria monocytogenes. Our data thus describe a biologically relevant basal activity of TBK1 and identify IRF7 as a novel player in the IFN-γ response.
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88
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Bose J, Pottosin II, Shabala SS, Palmgren MG, Shabala S. Calcium efflux systems in stress signaling and adaptation in plants. FRONTIERS IN PLANT SCIENCE 2011; 2:85. [PMID: 22639615 PMCID: PMC3355617 DOI: 10.3389/fpls.2011.00085] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 11/04/2011] [Indexed: 05/18/2023]
Abstract
Transient cytosolic calcium ([Ca(2+)](cyt)) elevation is an ubiquitous denominator of the signaling network when plants are exposed to literally every known abiotic and biotic stress. These stress-induced [Ca(2+)](cyt) elevations vary in magnitude, frequency, and shape, depending on the severity of the stress as well the type of stress experienced. This creates a unique stress-specific calcium "signature" that is then decoded by signal transduction networks. While most published papers have been focused predominantly on the role of Ca(2+) influx mechanisms to shaping [Ca(2+)](cyt) signatures, restoration of the basal [Ca(2+)](cyt) levels is impossible without both cytosolic Ca(2+) buffering and efficient Ca(2+) efflux mechanisms removing excess Ca(2+) from cytosol, to reload Ca(2+) stores and to terminate Ca(2+) signaling. This is the topic of the current review. The molecular identity of two major types of Ca(2+) efflux systems, Ca(2+)-ATPase pumps and Ca(2+)/H(+) exchangers, is described, and their regulatory modes are analyzed in detail. The spatial and temporal organization of calcium signaling networks is described, and the importance of existence of intracellular calcium microdomains is discussed. Experimental evidence for the role of Ca(2+) efflux systems in plant responses to a range of abiotic and biotic factors is summarized. Contribution of Ca(2+)-ATPase pumps and Ca(2+)/H(+) exchangers in shaping [Ca(2+)](cyt) signatures is then modeled by using a four-component model (plasma- and endo-membrane-based Ca(2+)-permeable channels and efflux systems) taking into account the cytosolic Ca(2+) buffering. It is concluded that physiologically relevant variations in the activity of Ca(2+)-ATPase pumps and Ca(2+)/H(+) exchangers are sufficient to fully describe all the reported experimental evidence and determine the shape of [Ca(2+)](cyt) signatures in response to environmental stimuli, emphasizing the crucial role these active efflux systems play in plant adaptive responses to environment.
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Affiliation(s)
- Jayakumar Bose
- School of Agricultural Science, University of TasmaniaHobart, TAS, Australia
| | - Igor I. Pottosin
- Centro Universitario de Investigaciones Biomédicas, Universidad de ColimaColima, México
| | | | | | - Sergey Shabala
- School of Agricultural Science, University of TasmaniaHobart, TAS, Australia
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89
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90
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Evasion and subversion of interferon-mediated antiviral immunity by Kaposi's sarcoma-associated herpesvirus: an overview. J Virol 2011; 85:10934-44. [PMID: 21775463 DOI: 10.1128/jvi.00687-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Viral invasion of a host cell triggers immune responses with both innate and adaptive components. The innate immune response involving the induction of type I interferons (alpha and beta interferons [IFN-α and -β]) constitutes the first line of antiviral defenses. The type I IFNs signal the transcription of a group of antiviral effector proteins, the IFN-stimulated genes (ISGs), which target distinct viral components and distinct stages of the viral life cycle, aiming to eliminate invading viruses. In the case of Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma (KS), a sudden upsurge of type I IFN-mediated innate antiviral signals is seen immediately following both primary de novo infection and viral lytic reactivation from latency. Potent subversion of these responses thus becomes mandatory for the successful establishment of a primary infection following viral entry as well as for efficient viral assembly and egress. This review gives a concise overview of the induction of the type I IFN signaling pathways in response to viral infection and provides a comprehensive understanding of the antagonizing effects exerted by KSHV on type I IFN pathways wielded at various stages of the viral life cycle. Information garnered from this review should result in a better understanding of KSHV biology essential for the development of immunotherapeutic strategies targeted toward KSHV-associated malignancies.
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91
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Oncogenic IRFs provide a survival advantage for Epstein-Barr virus- or human T-cell leukemia virus type 1-transformed cells through induction of BIC expression. J Virol 2011; 85:8328-37. [PMID: 21680528 DOI: 10.1128/jvi.00570-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
miR-155, processed from the B-cell integration cluster (BIC), is one of the few well-studied microRNAs (miRNAs) and is involved in both innate immunity and tumorigenesis. BIC/miR-155 is induced by distinct signaling pathways, but little is known about the underlying mechanisms. We have identified two conserved potential interferon (IFN) regulatory factor (IRF)-binding/interferon-stimulated response element motifs in the Bic gene promoter. Two oncogenic IRFs, IRF4 and -7, in addition to some other members of the family, bind to and significantly transactivate the Bic promoter. Correspondingly, the endogenous levels of IRF4 and -7 are correlated with that of the BIC transcript in Epstein-Barr virus (EBV)-transformed cells. However, RNA interference studies have shown that depletion of IRF4, rather than of IRF7, dramatically decreases the endogenous level of BIC by up to 70% in EBV- or human T-cell leukemia virus type 1 (HTLV1)-transformed cell lines and results in apoptosis and reduction of proliferation rates that are restored by transient expression of miR-155. Moreover, the endogenous levels of the miR-155 target, SHIP1, are consistently elevated in EBV- and HTLV1-transformed cell lines stably expressing shIRF4. In contrast, transient expression of IRF4 decreases the SHIP1 level in EBV-negative B cells. Furthermore, the level of IRF4 mRNA is significantly correlated with that of BIC in adult T-cell lymphoma/leukemia (ATLL) tumors. These results show that IRF4 plays an important role in the regulation of BIC in the context of EBV and HTLV1 infection. Our findings have identified Bic as the first miRNA-encoding gene for IRFs and provide evidence for a novel molecular mechanism underlying the IRF/BIC pathway in viral oncogenesis.
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92
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Yu Y, Hayward GS. The ubiquitin E3 ligase RAUL negatively regulates type i interferon through ubiquitination of the transcription factors IRF7 and IRF3. Immunity 2011; 33:863-77. [PMID: 21167755 DOI: 10.1016/j.immuni.2010.11.027] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 09/14/2010] [Accepted: 11/29/2010] [Indexed: 11/28/2022]
Abstract
In the course of combating infectious agents, type I interferon (IFN) needs a timely downregulation mechanism to avoid detrimental overreaction. Here we showed a mechanism for restraining type I IFN responses, which relied on a HECT domain ubiquitin (Ub) E3 ligase, RAUL. RAUL limited type I IFN production by directly catalyzing lysine 48-linked polyubiquitination of both interferon regulatory factor 7 (IRF7) and IRF3 followed by proteasome-dependent degradation. Suppression of RAUL by dominant-negative RAUL or siRNA augmented both basal and virus-induced production of type I IFN, which resulted in reduced viral replication. The Kaposi's sarcoma-associated herpes virus immediate-early lytic cycle trigger protein RTA recruited this mechanism to augment its countermeasures against the host antiviral response. These results unveil a previously unrecognized "brake mechanism" for type I IFN that maintains proper low amounts of type I IFN under physiological conditions and restrains its magnitude when the antiviral response intensifies.
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Affiliation(s)
- Yanxing Yu
- Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 1650 Orleans Street, CRB1 3M09, Baltimore, MD 21231, USA.
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93
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Abstract
Interferon regulatory factor 7 (IRF7) was originally identified in the context of Epstein-Barr virus (EBV) infection, and has since emerged as the crucial regulator of type I interferons (IFNs) against pathogenic infections, which activate IRF7 by triggering signaling cascades from pathogen recognition receptors (PRRs) that recognize pathogenic nucleic acids. Moreover, IRF7 is a multifunctional transcription factor, underscored by the fact that it is associated with EBV latency, in which IRF7 is induced as well as activated by the EBV principal oncoprotein latent membrane protein-1 (LMP1). Aberrant production of type I IFNs is associated with many types of diseases such as cancers and autoimmune disorders. Thus, tight regulation of IRF7 expression and activity is imperative in dictating appropriate type I IFN production for normal IFN-mediated physiological functions. Posttranslational modifications have important roles in regulation of IRF7 activity, exemplified by phosphorylation, which is indicative of its activation. Furthermore, mounting evidence has shed light on the importance of regulatory ubiquitination in activation of IRF7. Albeit these exciting findings have been made in the past decade since its discovery, many questions related to IRF7 remain to be addressed.
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94
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A tryptophan-rich motif in the human parainfluenza virus type 2 V protein is critical for the blockade of toll-like receptor 7 (TLR7)- and TLR9-dependent signaling. J Virol 2011; 85:4606-11. [PMID: 21345944 DOI: 10.1128/jvi.02012-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmacytoid dendritic cells (pDCs) do not produce alpha interferon (IFN-α) unless viruses cause a systemic infection or overcome the first-line defense provided by conventional DCs and macrophages. We show here that even paramyxoviruses, whose infections are restricted to the respiratory tract, have a V protein able to prevent Toll-like receptor 7 (TLR7)- and TLR9-dependent IFN-α induction specific to pDCs. Mutational analysis of human parainfluenza virus type 2 demonstrates that the second Trp residue of the Trp-rich motif (Trp-X(3)-Trp-X(9)-Trp) in the C-terminal domain unique to V, a determinant for IRF7 binding, is critical for the blockade of TLR7/9-dependent signaling.
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95
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Wen X, Abe T, Kukihara H, Taguwa S, Mori Y, Tani H, Kato N, Suzuki T, Tatsumi M, Moriishi K, Matsuura Y. Elimination of hepatitis C virus from hepatocytes by a selective activation of therapeutic molecules. PLoS One 2011; 6:e15967. [PMID: 21253612 PMCID: PMC3017098 DOI: 10.1371/journal.pone.0015967] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 12/07/2010] [Indexed: 12/28/2022] Open
Abstract
To eliminate hepatitis C virus (HCV) from infected hepatocytes, we generated two therapeutic molecules specifically activated in cells infected with HCV. A dominant active mutant of interferon (IFN) regulatory factor 7 (IRF7) and a negative regulator of HCV replication, VAP-C (Vesicle-associated membrane protein-associated protein subtype C), were fused with the C-terminal region of IPS-1 (IFNβ promoter stimulator-1), which includes an HCV protease cleavage site that was modified to be localized on the ER membrane, and designated cIRF7 and cVAP-C, respectively. In cells expressing the HCV protease, cIRF7 was cleaved and the processed fragment was migrated into the nucleus, where it activated various IFN promoters, including promoters of IFNα6, IFNβ, and IFN stimulated response element. Activation of the IFN promoters and suppression of viral RNA replication were observed in the HCV replicon cells and in cells infected with the JFH1 strain of HCV (HCVcc) by expression of cIRF7. Suppression of viral RNA replication was observed even in the IFN-resistant replicon cells by the expression of cIRF7. Expression of the cVAP-C also resulted in suppression of HCV replication in both the replicon and HCVcc infected cells. These results suggest that delivery of the therapeutic molecules into the liver of hepatitis C patients, followed by selective activation of the molecules in HCV-infected hepatocytes, is a feasible method for eliminating HCV.
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Affiliation(s)
- Xiaoyu Wen
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takayuki Abe
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Hiroshi Kukihara
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shuhei Taguwa
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yoshio Mori
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Hideki Tani
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Nobuyuki Kato
- Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan
| | - Tetsuro Suzuki
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masashi Tatsumi
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kohji Moriishi
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yoshiharu Matsuura
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- * E-mail:
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96
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Diversity of interferon antagonist activities mediated by NSP1 proteins of different rotavirus strains. J Virol 2010; 85:1970-9. [PMID: 21177809 DOI: 10.1128/jvi.01801-10] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Studies involving limited numbers of rotavirus (RV) strains have shown that the viral gene 5 product, NSP1, can antagonize beta interferon (IFN-β) expression by inducing the degradation of IFN-regulatory factors (IRFs) (IRF3, IRF5, and IRF7) or a component of the E3 ubiquitin ligase complex responsible for activating NF-κB (β-transducin repeat-containing protein [β-TrCP]). To gain a broader perspective of NSP1 activities, we examined various RV strains for the ability to inhibit IFN-β expression in human cells. We found that all strains encoding wild-type NSP1 impeded IFN-β expression but not always through IRF3 degradation. To identify other degradation targets involved in suppressing IFN-β expression, we used transient expression vectors to test the abilities of a diverse collection of NSP1 proteins to target IRF3, IRF5, IRF7, and β-TrCP for degradation. The results indicated that human RVs rely predominantly on the NSP1-induced degradation of IRF5 and IRF7 to suppress IFN signaling, whereas NSP1 proteins of animal RVs tended to target IRF3, IRF5, and IRF7, allowing the animal viruses a broader attack on the IFN-β signaling pathway. The results also suggested that the NSP1-induced degradation of β-TrCP is an uncommon mechanism of subverting IFN-β signaling but is one that can be shared with NSP1 proteins that induce IRF degradation. Our analysis reveals that the activities of NSP1 proteins are diverse, with no obvious correlations between degradations of pairs of target proteins. Thus, RVs have evolved functionally distinct approaches for subverting the host antiviral response, a property consistent with the immense sequence variation noted for NSP1 proteins.
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97
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Liang Q, Deng H, Sun CW, Townes TM, Zhu F. Negative regulation of IRF7 activation by activating transcription factor 4 suggests a cross-regulation between the IFN responses and the cellular integrated stress responses. THE JOURNAL OF IMMUNOLOGY 2010; 186:1001-10. [PMID: 21148039 DOI: 10.4049/jimmunol.1002240] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cells react to viral infection by exhibiting IFN-based innate immune responses and integrated stress responses, but little is known about the interrelationships between the two. In this study, we report a linkage between these two host-protective cellular mechanisms. We found that IFN regulatory factor (IRF)7, the master regulator of type I IFN gene expression, interacts with activating transcription factor (ATF)4, a key component of the integrated stress responses whose translation is induced by viral infection and various stresses. We have demonstrated that IRF7 upregulates ATF4 activity and expression, whereas ATF4 in return inhibits IRF7 activation, suggesting a cross-regulation between the IFN response and the cellular integrated stress response that controls host innate immune defense against viral infection.
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Affiliation(s)
- Qiming Liang
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
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98
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Sathish N, Zhu FX, Golub EE, Liang Q, Yuan Y. Mechanisms of autoinhibition of IRF-7 and a probable model for inactivation of IRF-7 by Kaposi's sarcoma-associated herpesvirus protein ORF45. J Biol Chem 2010; 286:746-56. [PMID: 20980251 DOI: 10.1074/jbc.m110.150920] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
IRF-7 is the master regulator of type I interferon-dependent immune responses controlling both innate and adaptive immunity. Given the significance of IRF-7 in the induction of immune responses, many viruses have developed strategies to inhibit its activity to evade or antagonize host antiviral responses. We previously demonstrated that ORF45, a KSHV immediate-early protein as well as a tegument protein of virions, interacts with IRF-7 and inhibits virus-mediated type I interferon induction by blocking IRF-7 phosphorylation and nuclear translocation (Zhu, F. X., King, S. M., Smith, E. J., Levy, D. E., and Yuan, Y. (2002) Proc. Natl. Acad. Sci. U.S.A. 99, 5573-5578). In this report, we sought to reveal the mechanism underlying the ORF45-mediated inactivation of IRF-7. We found that ORF45 interacts with the inhibitory domain of IRF-7. The most striking feature in the IRF-7 inhibitory domain is two α-helices H3 and H4 that contain many hydrophobic residues and two β-sheets located between the helices that are also very hydrophobic. These hydrophobic subdomains mediate intramolecular interactions that keep the molecule in a closed (inactive) form. Mutagenesis studies confirm the contribution of the hydrophobic helices and sheets to the autoinhibition of IRF-7 in the absence of viral signal. The binding of ORF45 to the critical domain of IRF-7 leads to a hypothesis that ORF45 may maintain the IRF-7 molecule in the closed form and prevent it from being activated in response to viral infection.
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Affiliation(s)
- Narayanan Sathish
- Department of Microbiology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania 19104, USA
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99
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Differential regulation of human papillomavirus type 8 by interferon regulatory factors 3 and 7. J Virol 2010; 85:178-88. [PMID: 20980500 DOI: 10.1128/jvi.00998-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The genus β human papillomavirus (HPV) type 8 is associated with nonmelanoma skin cancer in patients with epidermodysplasia verruciformis, and evidence for its protumorigenic potential in the general population increases. To date, strategies to suppress genus β HPV infections are limited. Interferon regulatory factors IRF-3 and IRF-7 play key roles in the activation of the innate immune response to viral infections. In this study, we show for the first time that both IRF-3 and IRF-7 regulate transcription of a papillomavirus, but with opposing effects. IRF-7, expressed in the suprabasal layers of human epidermis, increased HPV8 late promoter activity via direct binding to viral DNA. UV-B light-induced activation of the HPV8 promoter involved IRF-7 as a downstream effector. In contrast, IRF-3, expressed in all layers of human epidermis, induced strong HPV8 suppression in primary keratinocytes. IRF-3-mediated suppression prevailed over IRF-7-induced HPV8 transcription. Unlike the E6 oncoprotein of the mucosal high-risk HPV16, the HPV8 E6 protein did not bind to IRF-3 and only weakly antagonized its activity. Strong antiviral activity was also observed, when keratinocytes were treated with potent IRF-3 activators, poly(I:C) or RNA bearing 5' phosphates. In conclusion, we show that IRF-3 activation induces a state of cell-autonomous immunity against HPV in primary human keratinocytes. Our study suggests that local application of IRF-3-activating compounds might constitute an attractive novel therapeutic strategy against HPV8-associated diseases, particularly in epidermodysplasia verruciformis patients.
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100
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Siednienko J, Halle A, Nagpal K, Golenbock DT, Miggin SM. TLR3-mediated IFN-β gene induction is negatively regulated by the TLR adaptor MyD88 adaptor-like. Eur J Immunol 2010; 40:3150-60. [PMID: 20957750 DOI: 10.1002/eji.201040547] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 08/11/2010] [Accepted: 08/19/2010] [Indexed: 12/30/2022]
Abstract
There is limited insight into the mechanisms involved in the counterregulation of TLR. Given the important role of TLR3/TIR domain-containing adaptor-inducing IFN-β (TRIF)-dependent signalling in innate immunity, novel insights into its modulation is of significance in the context of many physiological and pathological processes. Herein, we sought to perform analysis to definitively assign a mechanistic role for MyD88 adaptor-like (Mal), an activator of TLR2/4 signalling, in the negative regulation of TLR3/TRIF signalling. Biochemical and functional analysis demonstrates that Mal negatively regulates TLR3, but not TLR4, mediated IFN-β production. Co-immunoprecipitation experiments demonstrate that Mal associates with IRF7 (IRF, IFN regulatory factor), not IRF3, and Mal specifically blocks IRF7 activation. In doing so, Mal impedes TLR3 ligand-induced IFN-β induction. Interestingly, Mal does not affect the induction of IL-6 and TNF-α upon TLR3 ligand engagement. Together, these data show that the TLR adaptor Mal interacts with IRF7 and, in doing so, impairs IFN-β induction through the positive regulatory domains I-III enhancer element of the IFN-β gene following poly(I:C) stimulation. Our findings offer a new mechanistic insight into TLR3/TRIF signalling through a hitherto unknown mechanism whereby Mal inhibits poly(I:C)-induced IRF7 activation and concomitant IFN-β production. Thus, Mal is essential in restricting TLR3 signalling thereby protecting the host from unwanted immunopathologies associated with excessive IFN-β production.
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Affiliation(s)
- Jakub Siednienko
- Institute of Immunology, Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Kildare, Ireland
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