251
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Uchikawa E, Lethier M, Malet H, Brunel J, Gerlier D, Cusack S. Structural Analysis of dsRNA Binding to Anti-viral Pattern Recognition Receptors LGP2 and MDA5. Mol Cell 2017; 62:586-602. [PMID: 27203181 PMCID: PMC4885022 DOI: 10.1016/j.molcel.2016.04.021] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 03/21/2016] [Accepted: 04/19/2016] [Indexed: 12/14/2022]
Abstract
RIG-I and MDA5 sense virus-derived short 5′ppp blunt-ended or long dsRNA, respectively, causing interferon production. Non-signaling LGP2 appears to positively and negatively regulate MDA5 and RIG-I signaling, respectively. Co-crystal structures of chicken (ch) LGP2 with dsRNA display a fully or semi-closed conformation depending on the presence or absence of nucleotide. LGP2 caps blunt, 3′ or 5′ overhang dsRNA ends with 1 bp longer overall footprint than RIG-I. Structures of 1:1 and 2:1 complexes of chMDA5 with short dsRNA reveal head-to-head packing rather than the polar head-to-tail orientation described for long filaments. chLGP2 and chMDA5 make filaments with a similar axial repeat, although less co-operatively for chLGP2. Overall, LGP2 resembles a chimera combining a MDA5-like helicase domain and RIG-I like CTD supporting both stem and end binding. Functionally, RNA binding is required for LGP2-mediated enhancement of MDA5 activation. We propose that LGP2 end-binding may promote nucleation of MDA5 oligomerization on dsRNA. chLPG2-dsRNA structures reveal RIG-I like end binding, but overhangs are possible chMDA5-dsRNA complex structures show head-to-head packing on short dsRNAs LGP2 also has MDA5-like behavior, coating dsRNA but with less cooperativity Both human and chicken LGP2 enhance MDA5 signaling in an RNA-dependent manner
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MESH Headings
- Adenosine Diphosphate/metabolism
- Adenosine Triphosphatases/chemistry
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/metabolism
- Adenosine Triphosphate/metabolism
- Animals
- Avian Proteins/chemistry
- Avian Proteins/genetics
- Avian Proteins/metabolism
- Binding Sites
- Cell Line
- Chickens
- DEAD Box Protein 58/chemistry
- DEAD Box Protein 58/genetics
- DEAD Box Protein 58/metabolism
- Humans
- Hydrolysis
- Interferon-Induced Helicase, IFIH1/chemistry
- Interferon-Induced Helicase, IFIH1/genetics
- Interferon-Induced Helicase, IFIH1/metabolism
- Models, Molecular
- Nucleic Acid Conformation
- Protein Binding
- Protein Interaction Domains and Motifs
- RNA, Double-Stranded/chemistry
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Receptors, Pattern Recognition/chemistry
- Receptors, Pattern Recognition/genetics
- Receptors, Pattern Recognition/metabolism
- Structure-Activity Relationship
- Transfection
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Affiliation(s)
- Emiko Uchikawa
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; University Grenoble Alpes, Centre National de la Recherche Scientifique, EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Mathilde Lethier
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; University Grenoble Alpes, Centre National de la Recherche Scientifique, EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Hélène Malet
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; University Grenoble Alpes, Centre National de la Recherche Scientifique, EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Joanna Brunel
- CIRI, International Center for Infectiology Research, Université de Lyon, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; Université Lyon 1, Centre International de Recherche en Infectiologie, 69007 Lyon, France
| | - Denis Gerlier
- CIRI, International Center for Infectiology Research, Université de Lyon, 69007 Lyon, France; Inserm, U1111, 69007 Lyon, France; CNRS, UMR5308, 69007 Lyon, France; Ecole Normale Supérieure de Lyon, 69007 Lyon, France; Université Lyon 1, Centre International de Recherche en Infectiologie, 69007 Lyon, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; University Grenoble Alpes, Centre National de la Recherche Scientifique, EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France.
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252
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Lui PY, Wong LYR, Ho TH, Au SWN, Chan CP, Kok KH, Jin DY. PACT Facilitates RNA-Induced Activation of MDA5 by Promoting MDA5 Oligomerization. THE JOURNAL OF IMMUNOLOGY 2017; 199:1846-1855. [PMID: 28760879 DOI: 10.4049/jimmunol.1601493] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 06/27/2017] [Indexed: 12/24/2022]
Abstract
MDA5 is a RIG-I-like cytoplasmic sensor of dsRNA and certain RNA viruses, such as encephalomyocarditis virus, for the initiation of the IFN signaling cascade in the innate antiviral response. The affinity of MDA5 toward dsRNA is low, and its activity becomes optimal in the presence of unknown cellular coactivators. In this article, we report an essential coactivator function of dsRNA-binding protein PACT in mediating the MDA5-dependent type I IFN response. Virus-induced and polyinosinic-polycytidylic acid-induced activation of MDA5 were severely impaired in PACT-knockout cells and attenuated in PACT-knockdown cells, but they were potentiated when PACT was overexpressed. PACT augmented IRF3-dependent type I IFN production subsequent to dsRNA-induced activation of MDA5. In contrast, PACT had no influence on MDA5-mediated activation of NF-κB. PACT required dsRNA interaction for its action on MDA5 and promoted dsRNA-induced oligomerization of MDA5. PACT had little stimulatory effect on MDA5 mutants deficient for oligomerization and filament assembly. PACT colocalized with MDA5 in the cytoplasm and potentiated MDA5 recruitment to the dsRNA ligand. Taken together, these findings suggest that PACT functions as an essential cellular coactivator of RIG-I, as well as MDA5, and it facilitates RNA-induced formation of MDA5 oligomers.
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Affiliation(s)
- Pak-Yin Lui
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong.,Shenzhen Institute of Research and Innovation, The University of Hong Kong, Nanshan, Shenzhen, China 518057
| | - Lok-Yin Roy Wong
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong.,Shenzhen Institute of Research and Innovation, The University of Hong Kong, Nanshan, Shenzhen, China 518057
| | - Ting-Hin Ho
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong.,Shenzhen Institute of Research and Innovation, The University of Hong Kong, Nanshan, Shenzhen, China 518057
| | - Shannon Wing Ngor Au
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong; and
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong.,Shenzhen Institute of Research and Innovation, The University of Hong Kong, Nanshan, Shenzhen, China 518057
| | - Kin-Hang Kok
- Shenzhen Institute of Research and Innovation, The University of Hong Kong, Nanshan, Shenzhen, China 518057; .,Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong; .,Shenzhen Institute of Research and Innovation, The University of Hong Kong, Nanshan, Shenzhen, China 518057
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253
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Ma Z, Yu Y, Xiao Y, Opriessnig T, Wang R, Yang L, Nan Y, Samal SK, Halbur PG, Zhang YJ. The middle half genome of interferon-inducing porcine reproductive and respiratory syndrome virus strain A2MC2 is essential for interferon induction. J Gen Virol 2017; 98:1720-1729. [PMID: 28699875 DOI: 10.1099/jgv.0.000819] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is known to antagonize the innate immune response. An atypical PRRSV strain A2MC2 is capable of inducing synthesis of type I interferons (IFNs) in cultured cells. Here, we show that the middle half of the A2MC2 genome is needed for triggering the IFN synthesis. First, a cDNA infectious clone of this atypical strain was constructed as a DNA-launched version. Virus recovery was achieved from the infectious clone and the recovered virus, rA2MC2, was characterized. The rA2MC2 retained the feature of IFN induction in cultured cells. Infection of pigs with the rA2MC2 virus caused viremia similar to that of the wild-type virus. Chimeric infectious clones were constructed by swapping genomic fragments with a cDNA clone of a moderately virulent strain VR-2385 that antagonizes IFN induction. Analysis of the rescued chimeric viruses demonstrated that the middle two fragments, ranging from nt4545 to nt12709 of the A2MC2 genome, were needed for the IFN induction, whereas the chimeric viruses containing any one of the two A2MC2 fragments failed to do so. The results and the cDNA infectious clone of the IFN-inducing A2MC2 will facilitate further study of its biology, ultimately leading towards the development of an improved vaccine against PRRS.
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Affiliation(s)
- Zexu Ma
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Ying Yu
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Yueqiang Xiao
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Tanja Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.,The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, Scotland, UK
| | - Rong Wang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Liping Yang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Yuchen Nan
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Siba K Samal
- Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
| | - Patrick G Halbur
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Yan-Jin Zhang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA
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254
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Lamborn IT, Jing H, Zhang Y, Drutman SB, Abbott JK, Munir S, Bade S, Murdock HM, Santos CP, Brock LG, Masutani E, Fordjour EY, McElwee JJ, Hughes JD, Nichols DP, Belkadi A, Oler AJ, Happel CS, Matthews HF, Abel L, Collins PL, Subbarao K, Gelfand EW, Ciancanelli MJ, Casanova JL, Su HC. Recurrent rhinovirus infections in a child with inherited MDA5 deficiency. J Exp Med 2017; 214:1949-1972. [PMID: 28606988 PMCID: PMC5502429 DOI: 10.1084/jem.20161759] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 04/13/2017] [Accepted: 05/26/2017] [Indexed: 12/15/2022] Open
Abstract
MDA5 is a cytosolic sensor of double-stranded RNA (ds)RNA including viral byproducts and intermediates. We studied a child with life-threatening, recurrent respiratory tract infections, caused by viruses including human rhinovirus (HRV), influenza virus, and respiratory syncytial virus (RSV). We identified in her a homozygous missense mutation in IFIH1 that encodes MDA5. Mutant MDA5 was expressed but did not recognize the synthetic MDA5 agonist/(ds)RNA mimic polyinosinic-polycytidylic acid. When overexpressed, mutant MDA5 failed to drive luciferase activity from the IFNB1 promoter or promoters containing ISRE or NF-κB sequence motifs. In respiratory epithelial cells or fibroblasts, wild-type but not knockdown of MDA5 restricted HRV infection while increasing IFN-stimulated gene expression and IFN-β/λ. However, wild-type MDA5 did not restrict influenza virus or RSV replication. Moreover, nasal epithelial cells from the patient, or fibroblasts gene-edited to express mutant MDA5, showed increased replication of HRV but not influenza or RSV. Thus, human MDA5 deficiency is a novel inborn error of innate and/or intrinsic immunity that causes impaired (ds)RNA sensing, reduced IFN induction, and susceptibility to the common cold virus.
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Affiliation(s)
- Ian T Lamborn
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
- Department of Pathology and Laboratory Medicine, Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Huie Jing
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Yu Zhang
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Scott B Drutman
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Jordan K Abbott
- Immunodeficiency Diagnosis and Treatment Program, Division of Allergy and Immunology, Department of Pediatrics, National Jewish Health, Denver, CO
| | - Shirin Munir
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | | | - Heardley M Murdock
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Celia P Santos
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Linda G Brock
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Evan Masutani
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Emmanuel Y Fordjour
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | | | | | - Dave P Nichols
- Division of Pediatric Pulmonary Medicine, Department of Pediatrics, National Jewish Health, Denver, CO
| | - Aziz Belkadi
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale UMR1163, Necker Hospital for Sick Children, Paris, France
- Paris Descartes University, Imagine Institute, Necker Hospital for Sick Children, Paris, France
| | - Andrew J Oler
- Bioinformatics and Computational Biosciences Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Corinne S Happel
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Helen F Matthews
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Laurent Abel
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale UMR1163, Necker Hospital for Sick Children, Paris, France
- Paris Descartes University, Imagine Institute, Necker Hospital for Sick Children, Paris, France
| | - Peter L Collins
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Kanta Subbarao
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Erwin W Gelfand
- Immunodeficiency Diagnosis and Treatment Program, Division of Allergy and Immunology, Department of Pediatrics, National Jewish Health, Denver, CO
| | - Michael J Ciancanelli
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY
| | - Jean-Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale UMR1163, Necker Hospital for Sick Children, Paris, France
- Paris Descartes University, Imagine Institute, Necker Hospital for Sick Children, Paris, France
- Pediatric Immuno-Hematology Unit, Necker Hospital for Sick Children, AP-HP, Paris, France
- Howard Hughes Medical Institute, New York, NY
| | - Helen C Su
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
- Department of Pathology and Laboratory Medicine, Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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255
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Aouadi W, Eydoux C, Coutard B, Martin B, Debart F, Vasseur JJ, Contreras JM, Morice C, Quérat G, Jung ML, Canard B, Guillemot JC, Decroly E. Toward the identification of viral cap-methyltransferase inhibitors by fluorescence screening assay. Antiviral Res 2017; 144:330-339. [PMID: 28676301 PMCID: PMC7113892 DOI: 10.1016/j.antiviral.2017.06.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/28/2017] [Accepted: 06/29/2017] [Indexed: 11/26/2022]
Abstract
Two highly pathogenic human coronaviruses associated with severe respiratory syndromes emerged since the beginning of the century. The severe acute respiratory syndrome SARS-coronavirus (CoV) spread first in southern China in 2003 with about 8000 infected cases in few months. Then in 2012, the Middle East respiratory syndrome (MERS-CoV) emerged from the Arabian Peninsula giving a still on-going epidemic associated to a high fatality rate. CoVs are thus considered a major health threat. This is especially true as no vaccine nor specific therapeutic are available against either SARS- or MERS-CoV. Therefore, new drugs need to be identified in order to develop antiviral treatments limiting CoV replication. In this study, we focus on the nsp14 protein, which plays a key role in virus replication as it methylates the RNA cap structure at the N7 position of the guanine. We developed a high-throughput N7-MTase assay based on Homogenous Time Resolved Fluorescence (HTRF®) and screened chemical libraries (2000 compounds) on the SARS-CoV nsp14. 20 compounds inhibiting the SARS-CoV nsp14 were further evaluated by IC50 determination and their specificity was assessed toward flavivirus- and human cap N7-MTases. Our results reveal three classes of compounds: 1) molecules inhibiting several MTases as well as the dengue virus polymerase activity unspecifically, 2) pan MTases inhibitors targeting both viral and cellular MTases, and 3) inhibitors targeting one viral MTase more specifically showing however activity against the human cap N7-MTase. These compounds provide a first basis towards the development of more specific inhibitors of viral methyltransferases.
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Affiliation(s)
- Wahiba Aouadi
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Cécilia Eydoux
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Bruno Coutard
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Baptiste Martin
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Françoise Debart
- IBMM, CNRS, Université Montpellier, ENSCM, Campus Triolet, Place E. Bataillon, 34095, Montpellier Cedex 05, France
| | - Jean Jacques Vasseur
- IBMM, CNRS, Université Montpellier, ENSCM, Campus Triolet, Place E. Bataillon, 34095, Montpellier Cedex 05, France
| | | | | | - Gilles Quérat
- UMR "Emergence des Pathologies Virales" (EPV: Aix-Marseille Université - IRD 190 - Inserm 1207 - EHESP), Marseille, France
| | | | - Bruno Canard
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | | | - Etienne Decroly
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France.
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256
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Okamoto M, Tsukamoto H, Kouwaki T, Seya T, Oshiumi H. Recognition of Viral RNA by Pattern Recognition Receptors in the Induction of Innate Immunity and Excessive Inflammation During Respiratory Viral Infections. Viral Immunol 2017; 30:408-420. [PMID: 28609250 DOI: 10.1089/vim.2016.0178] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The innate immune system is the first line of defense against virus infection that triggers the expression of type I interferon (IFN) and proinflammatory cytokines. Pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns, resulting in the induction of innate immune responses. Viral RNA in endosomes is recognized by Toll-like receptors, and cytoplasmic viral RNA is recognized by RIG-I-like receptors. The host innate immune response is critical for protection against virus infection. However, it has been postulated that an excessive inflammatory response in the lung caused by the innate immune response is harmful to the host and is a cause of lethality during influenza A virus infection. Although the deletion of genes encoding PRRs or proinflammatory cytokines does not improve the mortality of mice infected with influenza A virus, a partial block of the innate immune response is successful in decreasing the mortality rate of mice without a loss of protection against virus infection. In addition, morbidity and mortality rates are influenced by other factors. For example, secondary bacterial infection increases the mortality rate in patients with influenza A virus and in animal models of the disease, and environmental factors, such as cigarette smoke and fine particles, also affect the innate immune response. In this review, we summarize recent findings related to the role of PRRs in innate immune response during respiratory viral infection.
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Affiliation(s)
- Masaaki Okamoto
- 1 Department of Immunology, Faculty of Life Sciences, Graduate School of Medical Sciences, Kumamoto University , Kumamoto, Japan
| | - Hirotake Tsukamoto
- 1 Department of Immunology, Faculty of Life Sciences, Graduate School of Medical Sciences, Kumamoto University , Kumamoto, Japan
| | - Takahisa Kouwaki
- 1 Department of Immunology, Faculty of Life Sciences, Graduate School of Medical Sciences, Kumamoto University , Kumamoto, Japan
| | - Tsukasa Seya
- 2 Department of Microbiology and Immunology, Graduate School of Medicine, Hokkaido University , Sapporo, Japan
| | - Hiroyuki Oshiumi
- 1 Department of Immunology, Faculty of Life Sciences, Graduate School of Medical Sciences, Kumamoto University , Kumamoto, Japan .,3 PRESTO JST, Kumamoto, Japan
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257
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Abstract
RIG-I-like receptors (RLRs) are cytosolic innate immune sensors that detect pathogenic RNA and induce a systemic antiviral response. During the last decade, many studies focused on their molecular characterization and the identification of RNA agonists. Therefore, it became more and more clear that RLR activation needs to be carefully regulated, because constitutive signaling or detection of endogenous RNA through loss of specificity is detrimental. Here, we review the current understanding of RLR activation and selectivity. We specifically focus upon recent findings on the function of the helicase domain in discriminating between different RNAs, and whose malfunctioning causes serious autoimmune diseases.
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Affiliation(s)
- Charlotte Lässig
- From the Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, 81377 Munich and
| | - Karl-Peter Hopfner
- From the Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, 81377 Munich and
- the Center for Integrated Protein Sciences, 81377 Munich, Germany
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258
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Vajjhala PR, Ve T, Bentham A, Stacey KJ, Kobe B. The molecular mechanisms of signaling by cooperative assembly formation in innate immunity pathways. Mol Immunol 2017; 86:23-37. [PMID: 28249680 DOI: 10.1016/j.molimm.2017.02.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/16/2017] [Accepted: 02/19/2017] [Indexed: 12/25/2022]
Abstract
The innate immune system is the first line of defense against infection and responses are initiated by pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs). PRRs also detect endogenous danger-associated molecular patterns (DAMPs) that are released by damaged or dying cells. The major PRRs include the Toll-like receptor (TLR) family members, the nucleotide binding and oligomerization domain, leucine-rich repeat containing (NLR) family, the PYHIN (ALR) family, the RIG-1-like receptors (RLRs), C-type lectin receptors (CLRs) and the oligoadenylate synthase (OAS)-like receptors and the related protein cyclic GMP-AMP synthase (cGAS). The different PRRs activate specific signaling pathways to collectively elicit responses including the induction of cytokine expression, processing of pro-inflammatory cytokines and cell-death responses. These responses control a pathogenic infection, initiate tissue repair and stimulate the adaptive immune system. A central theme of many innate immune signaling pathways is the clustering of activated PRRs followed by sequential recruitment and oligomerization of adaptors and downstream effector enzymes, to form higher-order arrangements that amplify the response and provide a scaffold for proximity-induced activation of the effector enzymes. Underlying the formation of these complexes are co-operative assembly mechanisms, whereby association of preceding components increases the affinity for downstream components. This ensures a rapid immune response to a low-level stimulus. Structural and biochemical studies have given key insights into the assembly of these complexes. Here we review the current understanding of assembly of immune signaling complexes, including inflammasomes initiated by NLR and PYHIN receptors, the myddosomes initiated by TLRs, and the MAVS CARD filament initiated by RIG-1. We highlight the co-operative assembly mechanisms during assembly of each of these complexes.
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Affiliation(s)
- Parimala R Vajjhala
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - Adam Bentham
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; School of Biological Sciences, Flinders University, Adelaide, SA 5001, Australia
| | - Katryn J Stacey
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia.
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259
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Ding Z, An K, Xie L, Wu W, Zhang R, Wang D, Fang Y, Chen H, Xiao S, Fang L. Transmissible gastroenteritis virus infection induces NF-κB activation through RLR-mediated signaling. Virology 2017; 507:170-178. [PMID: 28448848 PMCID: PMC7111708 DOI: 10.1016/j.virol.2017.04.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 04/15/2017] [Accepted: 04/19/2017] [Indexed: 12/25/2022]
Abstract
Transmissible gastroenteritis virus (TGEV) is a porcine enteric coronavirus which causes lethal severe watery diarrhea in piglets. The pathogenesis of TGEV is strongly associated with inflammation. In this study, we found that TGEV infection activates transcription factors NF-κB, IRF3 and AP-1 in a time- and dose-dependent manner in porcine kidney cells. Treatment with the NF-κB-specific inhibitor BAY11-7082 significantly decreased TGEV-induced proinflammatory cytokine production, but did not affect virus replication. Phosphorylation of NF-κB subunit p65 and proinflammatory cytokine production were greatly decreased after knockdown of retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) or its adaptors MAVS and STING, while only slight reduction was observed in cells following silencing of Toll-like receptor adaptors, MyD88 and TRIF. Furthermore, TGEV infection significantly upregulated mRNA expression of RIG-I and MDA5. Taken together, our results indicate that the RLR signaling pathway is involved in TGEV-induced inflammatory responses. Transmissible gastroenteritis virus (TGEV) infection activates NF-κB. Inhibition of NF-κB activation does not affect TGEV replication. RLR signaling pathway is involved in TGEV-induced inflammatory responses. TGEV infection significantly upregulates mRNA expression of RIG-I and MDA5.
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Affiliation(s)
- Zhen Ding
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Kang An
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Lilan Xie
- College of Life Science and Technology, Wuhan Institute of Bioengineering, Wuhan 430415, China
| | - Wei Wu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Ruoxi Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Dang Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Ying Fang
- College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
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260
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Chemical and structural effects of base modifications in messenger RNA. Nature 2017; 541:339-346. [PMID: 28102265 DOI: 10.1038/nature21351] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/26/2016] [Indexed: 12/18/2022]
Abstract
A growing number of nucleobase modifications in messenger RNA have been revealed through advances in detection and RNA sequencing. Although some of the biochemical pathways that involve modified bases have been identified, research into the world of RNA modification - the epitranscriptome - is still in an early phase. A variety of chemical tools are being used to characterize base modifications, and the structural effects of known base modifications on RNA pairing, thermodynamics and folding are being determined in relation to their putative biological roles.
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261
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Abstract
Adenosine deaminases acting on RNA (ADARs) are zinc-containing enzymes that deaminate adenosine bases to inosines within dsRNA regions in transcripts. In short, structured dsRNA hairpins individual adenosine bases may be targeted specifically and edited with up to one hundred percent efficiency, leading to the production of alternative protein variants. However, the majority of editing events occur within longer stretches of dsRNA formed by pairing of repetitive sequences. Here, many different adenosine bases are potential targets but editing efficiency is usually much lower. Recent work shows that ADAR-mediated RNA editing is also required to prevent aberrant activation of antiviral innate immune sensors that detect viral dsRNA in the cytoplasm. Missense mutations in the ADAR1 RNA editing enzyme cause a fatal auto-inflammatory disease, Aicardi–Goutières syndrome (AGS) in affected children. In addition RNA editing by ADARs has been observed to increase in many cancers and also can contribute to vascular disease. Thus the role of RNA editing in the progression of various diseases can no longer be ignored. The ability of ADARs to alter the sequence of RNAs has also been used to artificially target model RNAs in vitro and in cells for RNA editing. Potentially this approach may be used to repair genetic defects and to alter genetic information at the RNA level. In this review we focus on the role of ADARs in disease development and progression and on their potential use to artificially modify RNAs in a targeted manner.
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Affiliation(s)
- Prajakta Bajad
- a Medical University of Vienna, Center of Anatomy and Cell Biology , Department of Cell- and Developmental Biology , Schwarzspanierstrasse, Vienna , Austria
| | - Michael F Jantsch
- a Medical University of Vienna, Center of Anatomy and Cell Biology , Department of Cell- and Developmental Biology , Schwarzspanierstrasse, Vienna , Austria
| | - Liam Keegan
- b CEITEC at Masaryk University , Kamenice, Czech Republic
| | - Mary O'Connell
- b CEITEC at Masaryk University , Kamenice, Czech Republic
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262
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Abstract
During viral and bacterial infections, pathogen-derived cytosolic nucleic acids are recognized by the intracellular RNA sensors retinoic acid-inducible gene I and melanoma-differentiated gene 5 and intracellular DNA sensors, including cyclic-di-GMP-AMP synthase, absent in melanoma 2, interferon (IFN)-gamma inducible protein 16, polymerase III, and so on. Binding of intracellular nucleic acids to these sensors activates downstream signaling cascades, resulting in the production of type I IFNs and pro-inflammatory cytokines to induce appropriate systematic immune responses. While these sensors also recognize endogenous nucleic acids and activate immune responses, they can discriminate between self- and non-self-nucleic acids. However, dysfunction of these sensors or failure of regulatory mechanisms causes aberrant activation of immune response and autoimmune disorders. In this review, we focus on how intracellular immune sensors recognize exogenous nucleic acids and activate the innate immune system, and furthermore, how autoimmune diseases result from dysfunction of these sensors.
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Affiliation(s)
- Daisuke Ori
- a Laboratory of Molecular Immunobiology , Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Takayama-cho , Ikoma , Nara , Japan
| | - Motoya Murase
- a Laboratory of Molecular Immunobiology , Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Takayama-cho , Ikoma , Nara , Japan
| | - Taro Kawai
- a Laboratory of Molecular Immunobiology , Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Takayama-cho , Ikoma , Nara , Japan
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263
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Modelling viral infections using zebrafish: Innate immune response and antiviral research. Antiviral Res 2017; 139:59-68. [DOI: 10.1016/j.antiviral.2016.12.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 12/21/2016] [Indexed: 12/20/2022]
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264
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Fitzgerald ME, Rawling DC, Potapova O, Ren X, Kohlway A, Pyle AM. Selective RNA targeting and regulated signaling by RIG-I is controlled by coordination of RNA and ATP binding. Nucleic Acids Res 2017; 45:1442-1454. [PMID: 28180316 PMCID: PMC5388420 DOI: 10.1093/nar/gkw816] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/31/2016] [Accepted: 09/03/2016] [Indexed: 12/25/2022] Open
Abstract
RIG-I is an innate immune receptor that detects and responds to infection by deadly RNA viruses such as influenza, and Hepatitis C. In the cytoplasm, RIG-I is faced with a difficult challenge: it must sensitively detect viral RNA while ignoring the abundance of host RNA. It has been suggested that RIG-I has a ‘proof-reading’ mechanism for rejecting host RNA targets, and that disruptions of this selectivity filter give rise to autoimmune diseases. Here, we directly monitor RNA proof-reading by RIG-I and we show that it is controlled by a set of conserved amino acids that couple RNA and ATP binding to the protein (Motif III). Mutations of this motif directly modulate proof-reading by eliminating or enhancing selectivity for viral RNA, with major implications for autoimmune disease and cancer. More broadly, the results provide a physical explanation for the ATP-gated behavior of SF2 RNA helicases and receptor proteins.
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MESH Headings
- Adenosine Triphosphatases/chemistry
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/metabolism
- Adenosine Triphosphate/metabolism
- Amino Acid Substitution
- Autoimmunity
- Binding Sites/genetics
- DEAD Box Protein 58/genetics
- DEAD Box Protein 58/immunology
- DEAD Box Protein 58/metabolism
- HEK293 Cells
- Humans
- Immunity, Innate
- Models, Molecular
- Mutagenesis, Site-Directed
- Neoplasms/genetics
- Neoplasms/metabolism
- Protein Interaction Domains and Motifs
- RNA/chemistry
- RNA/genetics
- RNA/metabolism
- RNA Viruses/genetics
- RNA Viruses/immunology
- RNA Viruses/pathogenicity
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Receptors, Immunologic
- Receptors, Pattern Recognition/chemistry
- Receptors, Pattern Recognition/genetics
- Receptors, Pattern Recognition/metabolism
- Signal Transduction
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Affiliation(s)
- Megan E. Fitzgerald
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - David C. Rawling
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Olga Potapova
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Xiaoming Ren
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Andrew Kohlway
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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265
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Morse ZJ, Horwitz MS. Innate Viral Receptor Signaling Determines Type 1 Diabetes Onset. Front Endocrinol (Lausanne) 2017; 8:249. [PMID: 29018409 PMCID: PMC5623193 DOI: 10.3389/fendo.2017.00249] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 09/12/2017] [Indexed: 12/25/2022] Open
Abstract
Heritable susceptibility of the autoimmune disorder, type 1 diabetes (T1D), only partially equates for the incidence of the disease. Significant evidence attributes several environmental stressors, such as vitamin D deficiency, gut microbiome, dietary antigens, and most notably virus infections in triggering the onset of T1D in these genetically susceptible individuals. Extensive epidemiological and clinical studies have provided credibility to this causal relationship. Infection by the enterovirus, coxsackievirus B, has been closely associated with onset of T1D and is considered a significant etiological agent for disease induction. Recognition of viral antigens via innate pathogen-recognition receptors induce inflammatory events which contribute to autoreactivity of pancreatic self-antigens and ultimately the destruction of insulin-secreting beta cells. The activation of these specific innate pathways and expression of inflammatory molecules, including type I and III interferon, prime the immune system to elicit either a protective regulatory response or a diabetogenic effector response. Therefore, sensing of viral antigens by retinoic acid-inducible gene I-like receptors and toll-like receptors may be detrimental to inducing autoreactivity initiated by viral stress and resulting in T1D.
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Affiliation(s)
- Zachary J. Morse
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Marc S. Horwitz
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Marc S. Horwitz,
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266
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Si Y, Zhang Y, Chen Z, Zhou R, Zhang Y, Hao D, Yan D. Posttranslational Modification Control of Inflammatory Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1024:37-61. [DOI: 10.1007/978-981-10-5987-2_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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267
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Lang X, Tang T, Jin T, Ding C, Zhou R, Jiang W. TRIM65-catalized ubiquitination is essential for MDA5-mediated antiviral innate immunity. J Exp Med 2016; 214:459-473. [PMID: 28031478 PMCID: PMC5294850 DOI: 10.1084/jem.20160592] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 09/07/2016] [Accepted: 12/01/2016] [Indexed: 12/24/2022] Open
Abstract
MDA5 plays a critical role in antiviral innate immunity by functioning as a cytoplasmic double-stranded RNA sensor that can activate type I interferon signaling pathways, but the mechanism for the activation of MDA5 is poorly understood. Here, we show that TRIM65 specifically interacts with MDA5 and promotes K63-linked ubiquitination of MDA5 at lysine 743, which is critical for MDA5 oligomerization and activation. Trim65 deficiency abolishes MDA5 agonist or encephalomyocarditis virus (EMCV)-induced interferon regulatory factor 3 (IRF3) activation and type I interferon production but has no effect on retinoic acid-inducible I (RIG-I), Toll-like receptor 3 (TLR3), or cyclic GMP-AMP synthase signaling pathways. Importantly, Trim65-/- mice are more susceptible to EMCV infection than controls and cannot produce type I interferon in vivo. Collectively, our results identify TRIM65 as an essential component for the MDA5 signaling pathway and provide physiological evidence showing that ubiquitination is important for MDA5 oligomerization and activation.
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Affiliation(s)
- Xueting Lang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei 230027, China.,Innovation Center for Cell Signaling Network, University of Science and Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230027, China
| | - Tiantian Tang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei 230027, China
| | - Tengchuan Jin
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei 230027, China
| | - Chen Ding
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai 200433, China .,State Key Laboratory of Proteomics, National Center for Protein Sciences (The PHOENIX Center, Beijing), Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 102206, China
| | - Rongbin Zhou
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei 230027, China .,Innovation Center for Cell Signaling Network, University of Science and Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230027, China
| | - Wei Jiang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei 230027, China .,Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230027, China
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268
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Domsgen E, Lind K, Kong L, Hühn MH, Rasool O, van Kuppeveld F, Korsgren O, Lahesmaa R, Flodström-Tullberg M. An IFIH1 gene polymorphism associated with risk for autoimmunity regulates canonical antiviral defence pathways in Coxsackievirus infected human pancreatic islets. Sci Rep 2016; 6:39378. [PMID: 28000722 PMCID: PMC5175199 DOI: 10.1038/srep39378] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/23/2016] [Indexed: 02/08/2023] Open
Abstract
The IFIH1 gene encodes the pattern recognition receptor MDA5. A common polymorphism in IFIH1 (rs1990760, A946T) confers increased risk for autoimmune disease, including type 1-diabetes (T1D). Coxsackievirus infections are linked to T1D and cause beta-cell damage in vitro. Here we demonstrate that the rs1990760 polymorphism regulates the interferon (IFN) signature expressed by human pancreatic islets following Coxsackievirus infection. A strong IFN signature was associated with high expression of IFNλ1 and IFNλ2, linking rs1990760 to the expression of type III IFNs. In the high-responding genotype, IRF-1 expression correlated with that of type III IFN, suggesting a positive-feedback on type III IFN transcription. In summary, our study uncovers an influence of rs1990760 on the canonical effector function of MDA5 in response to an acute infection of primary human parenchymal cells with a clinically relevant virus linked to human T1D. It also highlights a previously unrecognized connection between the rs1990760 polymorphism and the expression level of type III IFNs.
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Affiliation(s)
- Erna Domsgen
- The Center for Infectious Medicine, Department of Medicine HS, Karolinska Institutet, Karolinska University Hospital, Stockholm, 141 86, Sweden
| | - Katharina Lind
- The Center for Infectious Medicine, Department of Medicine HS, Karolinska Institutet, Karolinska University Hospital, Stockholm, 141 86, Sweden
| | - Lingjia Kong
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, 205 20, Finland
| | - Michael H Hühn
- The Center for Infectious Medicine, Department of Medicine HS, Karolinska Institutet, Karolinska University Hospital, Stockholm, 141 86, Sweden
| | - Omid Rasool
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, 205 20, Finland
| | - Frank van Kuppeveld
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, 3584, The Netherlands
| | - Olle Korsgren
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, 751 05, Sweden
| | - Riitta Lahesmaa
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, 205 20, Finland
| | - Malin Flodström-Tullberg
- The Center for Infectious Medicine, Department of Medicine HS, Karolinska Institutet, Karolinska University Hospital, Stockholm, 141 86, Sweden.,Institute of Biosciences and Medical Technologies, University of Tampere, Tampere, 33520, Finland
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269
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McFadden MJ, Gokhale NS, Horner SM. Protect this house: cytosolic sensing of viruses. Curr Opin Virol 2016; 22:36-43. [PMID: 27951430 PMCID: PMC5346041 DOI: 10.1016/j.coviro.2016.11.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/22/2016] [Indexed: 02/06/2023]
Abstract
Cells are equipped with pattern recognition receptors to sense invading viruses. Nucleic acids of RNA viruses are sensed by RIG-I like receptors in the cytosol. Foreign DNA is sensed by cGAS and other DNA sensors in the cytosol. These pattern recognition receptors activate adaptor proteins to initiate antiviral innate immune responses.
The ability to recognize invading viral pathogens and to distinguish their components from those of the host cell is critical to initiate the innate immune response. The efficiency of this detection is an important factor in determining the susceptibility of the cell to viral infection. Innate sensing of viruses is, therefore, an indispensable step in the line of defense for cells and organisms. Recent discoveries have uncovered novel sensors of viral components and hallmarks of infection, as well as mechanisms by which cells discriminate between self and non-self. This review highlights the mechanisms used by cells to detect viral pathogens in the cytosol, and recent advances in the field of cytosolic sensing of viruses.
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Affiliation(s)
- Michael J McFadden
- Department of Molecular Genetics & Microbiology, Duke University Medical Center Durham, NC 27710, USA
| | - Nandan S Gokhale
- Department of Molecular Genetics & Microbiology, Duke University Medical Center Durham, NC 27710, USA
| | - Stacy M Horner
- Department of Molecular Genetics & Microbiology, Duke University Medical Center Durham, NC 27710, USA; Department of Medicine, Duke University Medical Center Durham, NC 27710, USA.
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270
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Chiang C, Gack MU. Post-translational Control of Intracellular Pathogen Sensing Pathways. Trends Immunol 2016; 38:39-52. [PMID: 27863906 PMCID: PMC5580928 DOI: 10.1016/j.it.2016.10.008] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 01/15/2023]
Abstract
Mammalian cells recognize virus-derived nucleic acids using a defined set of intracellular sensors including the DNA sensors cyclic GMP–AMP (cGAMP) synthase (cGAS) and interferon gamma (IFNγ)-inducible protein 16 (IFI16) as well as viral RNA receptors of the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) family. Following innate immune recognition, these sensors launch an immune response that is characterized by the transcriptional upregulation of many antiviral molecules, including proinflammatory cytokines, chemokines, and IFN-stimulated genes. Recent studies have demonstrated that the signal transduction initiated by these sensors is sophisticatedly regulated by post-translational modifications (PTMs) resulting in a robust yet ‘tunable’ cytokine response to maintain immune homeostasis. Here we summarize recent advances in our understanding of how PTMs and regulatory enzymes control the signaling activity of RLRs, cGAS, and IFI16 as well as their proximal adaptor proteins. Positive feedforward regulatory mechanisms serve as an important means of signal amplification to ensure an effective innate immune response. However, negative regulatory circuits are essential for the prevention of premature or overactive proinflammatory responses, which could have harmful consequences for the host organism. Phosphorylation and different types of polyubiquitin chains, particularly K63-linked ubiquitination, are important for fine-tuning signaling initiated by intracellular viral RNA and DNA receptors. Acetylation, glutamylation, and deamidation of innate immune sensors or components in their signaling pathways also dynamically modulate antiviral cytokine induction. Insight into the molecular mechanisms and regulatory enzymes that modulate innate sensing pathways may lead to therapeutics to boost antiviral immunity or dampen proinflammatory/autoimmune responses.
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Affiliation(s)
- Cindy Chiang
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, USA
| | - Michaela U Gack
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, USA.
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271
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Vabret N, Bhardwaj N, Greenbaum BD. Sequence-Specific Sensing of Nucleic Acids. Trends Immunol 2016; 38:53-65. [PMID: 27856145 DOI: 10.1016/j.it.2016.10.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 12/25/2022]
Abstract
Innate immune cells are endowed with many nucleic acid receptors, but the role of sequence in the detection of foreign organisms remains unclear. Can sequence patterns influence recognition? In addition, how can we infer those patterns from sequence data? Here, we detail recent computational and experimental evidence associated with sequence-specific sensing. We review the mechanisms underlying the detection and discrimination of foreign sequences from self. We also describe quantitative approaches used to infer the stimulatory capacity of a given pathogen nucleic acid species, and the influence of sequence-specific sensing on host-pathogen coevolution, including endogenous sequences of foreign origin. Finally, we speculate how further studies of sequence-specific sensing will be useful to improve vaccine design, gene therapy and cancer treatment.
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Affiliation(s)
- Nicolas Vabret
- Tisch Cancer Institute, Departments of Medicine, Hematology, and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Departments of Oncological Sciences and Pathology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Nina Bhardwaj
- Tisch Cancer Institute, Departments of Medicine, Hematology, and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Benjamin D Greenbaum
- Tisch Cancer Institute, Departments of Medicine, Hematology, and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Departments of Oncological Sciences and Pathology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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272
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Pugh C, Kolaczkowski O, Manny A, Korithoski B, Kolaczkowski B. Resurrecting ancestral structural dynamics of an antiviral immune receptor: adaptive binding pocket reorganization repeatedly shifts RNA preference. BMC Evol Biol 2016; 16:241. [PMID: 27825296 PMCID: PMC5101713 DOI: 10.1186/s12862-016-0818-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 10/28/2016] [Indexed: 02/07/2023] Open
Abstract
Background Although resurrecting ancestral proteins is a powerful tool for understanding the molecular-functional evolution of gene families, nearly all studies have examined proteins functioning in relatively stable biological processes. The extent to which more dynamic systems obey the same ‘rules’ governing stable processes is unclear. Here we present the first detailed investigation of the functional evolution of the RIG-like receptors (RLRs), a family of innate immune receptors that detect viral RNA in the cytoplasm. Results Using kinetic binding assays and molecular dynamics simulations of ancestral proteins, we demonstrate how a small number of adaptive protein-coding changes repeatedly shifted the RNA preference of RLRs throughout animal evolution by reorganizing the shape and electrostatic distribution across the RNA binding pocket, altering the hydrogen bond network between the RLR and its RNA target. In contrast to observations of proteins involved in metabolism and development, we find that RLR-RNA preference ‘flip flopped’ between two functional states, and shifts in RNA preference were not always coupled to gene duplications or speciation events. We demonstrate at least one reversion of RLR-RNA preference from a derived to an ancestral function through a novel structural mechanism, indicating multiple structural implementations of similar functions. Conclusions Our results suggest a model in which frequent shifts in selection pressures imposed by an evolutionary arms race preclude the long-term functional optimization observed in stable biological systems. As a result, the evolutionary dynamics of immune receptors may be less constrained by structural epistasis and historical contingency. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0818-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Charles Pugh
- Department of Microbiology & Cell Science and Institute for Food and Agricultural Sciences, University of Florida, Gainesville, USA
| | - Oralia Kolaczkowski
- Department of Microbiology & Cell Science and Institute for Food and Agricultural Sciences, University of Florida, Gainesville, USA
| | - Austin Manny
- Department of Microbiology & Cell Science and Institute for Food and Agricultural Sciences, University of Florida, Gainesville, USA
| | - Bryan Korithoski
- Department of Microbiology & Cell Science and Institute for Food and Agricultural Sciences, University of Florida, Gainesville, USA
| | - Bryan Kolaczkowski
- Department of Microbiology & Cell Science and Institute for Food and Agricultural Sciences, University of Florida, Gainesville, USA. .,Genetics Institute, University of Florida, Gainesville, USA.
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273
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Ubiquitin in Influenza Virus Entry and Innate Immunity. Viruses 2016; 8:v8100293. [PMID: 27783058 PMCID: PMC5086625 DOI: 10.3390/v8100293] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 12/20/2022] Open
Abstract
Viruses are obligatory cellular parasites. Their mission is to enter a host cell, to transfer the viral genome, and to replicate progeny whilst diverting cellular immunity. The role of ubiquitin is to regulate fundamental cellular processes such as endocytosis, protein degradation, and immune signaling. Many viruses including influenza A virus (IAV) usurp ubiquitination and ubiquitin-like modifications to establish infection. In this focused review, we discuss how ubiquitin and unanchored ubiquitin regulate IAV host cell entry, and how histone deacetylase 6 (HDAC6), a cytoplasmic deacetylase with ubiquitin-binding activity, mediates IAV capsid uncoating. We also discuss the roles of ubiquitin in innate immunity and its implications in the IAV life cycle.
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274
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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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275
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Loss of RIG-I leads to a functional replacement with MDA5 in the Chinese tree shrew. Proc Natl Acad Sci U S A 2016; 113:10950-5. [PMID: 27621475 DOI: 10.1073/pnas.1604939113] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The function of the RIG-I-like receptors (RLRs; including RIG-I, MDA5, and LGP2) as key cytoplasmic sensors of viral pathogen-associated molecular patterns (PAMPs) has been subjected to numerous pathogenic challenges and has undergone a dynamic evolution. We found evolutionary evidence that RIG-I was lost in the Chinese tree shrew lineage. Along with the loss of RIG-I, both MDA5 (tMDA5) and LGP2 (tLGP2) have undergone strong positive selection in the tree shrew. tMDA5 or tMDA5/tLGP2 could sense Sendai virus (an RNA virus posed as a RIG-I agonist) for inducing type I IFN, although conventional RIG-I and MDA5 were thought to recognize distinct RNA structures and viruses. tMDA5 interacted with adaptor tMITA (STINGTMEM173/ERIS), which was reported to bind only with RIG-I. The positively selected sites in tMDA5 endowed the substitute function for the lost RIG-I. These findings provided insights into the adaptation and functional diversity of innate antiviral activity in vertebrates.
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276
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Windgassen TA, Keck JL. An aromatic-rich loop couples DNA binding and ATP hydrolysis in the PriA DNA helicase. Nucleic Acids Res 2016; 44:9745-9757. [PMID: 27484483 PMCID: PMC5175346 DOI: 10.1093/nar/gkw690] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 11/13/2022] Open
Abstract
Helicases couple ATP hydrolysis to nucleic acid binding and unwinding via molecular mechanisms that remain poorly defined for most enzyme subfamilies within the superfamily 2 (SF2) helicase group. A crystal structure of the PriA SF2 DNA helicase, which governs restart of prematurely terminated replication processes in bacteria, revealed the presence of an aromatic-rich loop (ARL) on the presumptive DNA-binding surface of the enzyme. The position and sequence of the ARL was similar to loops known to couple ATP hydrolysis with DNA binding in a subset of other SF2 enzymes, however, the roles of the ARL in PriA had not been investigated. Here, we show that changes within the ARL sequence uncouple PriA ATPase activity from DNA binding. In vitro protein-DNA crosslinking experiments define a residue- and nucleotide-specific interaction map for PriA, showing that the ARL binds replication fork junctions whereas other sites bind the leading or lagging strands. We propose that DNA binding to the ARL allosterically triggers ATP hydrolysis in PriA. Additional SF2 helicases with similarly positioned loops may also couple DNA binding to ATP hydrolysis using related mechanisms.
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Affiliation(s)
- Tricia A Windgassen
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
| | - James L Keck
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
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277
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Chatterjee S, Basler CF, Amarasinghe GK, Leung DW. Molecular Mechanisms of Innate Immune Inhibition by Non-Segmented Negative-Sense RNA Viruses. J Mol Biol 2016; 428:3467-82. [PMID: 27487481 DOI: 10.1016/j.jmb.2016.07.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/25/2016] [Accepted: 07/25/2016] [Indexed: 12/25/2022]
Abstract
The host innate immune system serves as the first line of defense against viral infections. Germline-encoded pattern recognition receptors detect molecular patterns associated with pathogens and activate innate immune responses. Of particular relevance to viral infections are those pattern recognition receptors that activate type I interferon responses, which establish an antiviral state. The order Mononegavirales is composed of viruses that possess single-stranded, non-segmented negative-sense (NNS) RNA genomes and are important human pathogens that consistently antagonize signaling related to type I interferon responses. NNS viruses have limited encoding capacity compared to many DNA viruses, and as a likely consequence, most open reading frames encode multifunctional viral proteins that interact with host factors in order to evade host cell defenses while promoting viral replication. In this review, we will discuss the molecular mechanisms of innate immune evasion by select NNS viruses. A greater understanding of these interactions will be critical in facilitating the development of effective therapeutics and viral countermeasures.
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Affiliation(s)
- Srirupa Chatterjee
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Christopher F Basler
- Center of Microbial Pathogenesis, Georgia State University, Atlanta, GA 30303, USA.
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Daisy W Leung
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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278
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Abstract
Immune sensing of foreign nucleic acids among abundant self nucleic acids is a hallmark of virus detection and antiviral defence. Efficient antiviral defence requires a balanced process of sensing foreign nucleic acids and ignoring self nucleic acids. This balance is accomplished by a multilevel, fail-safe system which combines immune sensing of pathogen-specific nucleic acid structures with specific labelling of self nucleic acids and nuclease-mediated degradation. Cellular localization of nucleic acids, nucleic acid secondary structure, nucleic acid sequence and chemical modification all contribute to selective recognition of foreign nucleic acids. Nucleic acid sensing occurs in immune cells and non-immune cells and results in antiviral responses that include the induction of antiviral effector proteins, the secretion of cytokines alarming neighbouring cells, the secretion of chemokines, which attract immune cells, and the induction of cell death. Vertebrate cells cannot completely avoid the occurrence of endogenous self nucleic acid structures with immunostimulatory properties. Therefore, additional mechanisms involving self-nucleic acid modification and nuclease-mediated degradation are necessary to diminish uncontrolled immune activation. Viruses have established sophisticated mechanisms to exploit and adopt endogenous tolerance mechanisms or to avoid the presentation of characteristic molecular features recognized by nucleic acid sensing receptors.
The detection of viruses by the immune system is mediated predominantly by the sensing of nucleic acids. Here, the authors review our current understanding of how this complex immune sensory system discriminates self from non-self nucleic acids to reliably detect pathogenic viruses, and discuss the future perspectives and implications for human disease. Innate immunity against pathogens relies on an array of immune receptors to detect molecular patterns that are characteristic of the pathogens, including receptors that are specialized in the detection of foreign nucleic acids. In vertebrates, nucleic acid sensing is the dominant antiviral defence pathway. Stimulation of nucleic acid receptors results in antiviral immune responses with the production of type I interferon (IFN), as well as the expression of IFN-stimulated genes, which encode molecules such as cell-autonomous antiviral effector proteins. This Review summarizes the tremendous progress that has been made in understanding how this sophisticated immune sensory system discriminates self from non-self nucleic acids in order to reliably detect pathogenic viruses.
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Affiliation(s)
- Martin Schlee
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany
| | - Gunther Hartmann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany
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279
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Yan Q, Liu Q, Li MM, Li FH, Zhu B, Wang JZ, Lu YP, Liu J, Wu J, Zheng X, Lu MJ, Wang BJ, Yang DL. Molecular cloning, characterization and expression analysis of woodchuck retinoic acid-inducible gene I. ACTA ACUST UNITED AC 2016; 36:335-343. [PMID: 27376800 DOI: 10.1007/s11596-016-1588-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/17/2016] [Indexed: 12/25/2022]
Abstract
Cytosolic retinoic acid-inducible gene I (RIG-I) is an important innate immune RNA sensor and can induce antiviral cytokines, e.g., interferon-β (IFN-β). Innate immune response to hepatitis B virus (HBV) plays a pivotal role in viral clearance and persistence. However, knowledge of the role that RIG-I plays in HBV infection is limited. The woodchuck is a valuable model for studying HBV infection. To characterize the molecular basis of woodchuck RIG-I (wRIG-I), we analyzed the complete coding sequences (CDSs) of wRIG-I, containing 2778 base pairs that encode 925 amino acids. The deduced wRIG-I protein was 106.847 kD with a theoretical isoelectric point (pI) of 6.07, and contained three important functional structures [caspase activation and recruitment domains (CARDs), DExD/H-box helicases, and a repressor domain (RD)]. In woodchuck fibroblastoma cell line (WH12/6), wRIG-I-targeted small interfering RNA (siRNA) down-regulated RIG-I and its downstrean effector-IFN-β transcripts under RIG-I' ligand, 5'-ppp double stranded RNA (dsRNA) stimulation. We also measured mRNA levels of wRIG-I in different tissues from healthy woodchucks and in the livers from woodchuck hepatitis virus (WHV)-infected woodchucks. The basal expression levels of wRIG-I were abundant in the kidney and liver. Importantly, wRIG-I was significantly up-regulated in acutely infected woodchuck livers, suggesting that RIG-I might be involved in WHV infection. These results may characterize RIG-I in the woodchuck model, providing a strong basis for further study on RIG-I-mediated innate immunity in HBV infection.
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Affiliation(s)
- Qi Yan
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Qin Liu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Meng-Meng Li
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Fang-Hui Li
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Bin Zhu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jun-Zhong Wang
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Yin-Ping Lu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jia Liu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jun Wu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xin Zheng
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Meng-Ji Lu
- Institute of Virology, University of Duisburg-Essen, Essen, 45149, Germany
| | - Bao-Ju Wang
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Dong-Liang Yang
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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280
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Liddicoat BJ, Hartner JC, Piskol R, Ramaswami G, Chalk AM, Kingsley PD, Sankaran VG, Wall M, Purton LE, Seeburg PH, Palis J, Orkin SH, Lu J, Li JB, Walkley CR. Adenosine-to-inosine RNA editing by ADAR1 is essential for normal murine erythropoiesis. Exp Hematol 2016; 44:947-63. [PMID: 27373493 DOI: 10.1016/j.exphem.2016.06.250] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 06/02/2016] [Indexed: 11/17/2022]
Abstract
Adenosine deaminases that act on RNA (ADARs) convert adenosine residues to inosine in double-stranded RNA. In vivo, ADAR1 is essential for the maintenance of hematopoietic stem/progenitors. Whether other hematopoietic cell types also require ADAR1 has not been assessed. Using erythroid- and myeloid-restricted deletion of Adar1, we demonstrate that ADAR1 is dispensable for myelopoiesis but is essential for normal erythropoiesis. Adar1-deficient erythroid cells display a profound activation of innate immune signaling and high levels of cell death. No changes in microRNA levels were found in ADAR1-deficient erythroid cells. Using an editing-deficient allele, we demonstrate that RNA editing is the essential function of ADAR1 during erythropoiesis. Mapping of adenosine-to-inosine editing in purified erythroid cells identified clusters of hyperedited adenosines located in long 3'-untranslated regions of erythroid-specific transcripts and these are ADAR1-specific editing events. ADAR1-mediated RNA editing is essential for normal erythropoiesis.
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Affiliation(s)
- Brian J Liddicoat
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
| | - Jochen C Hartner
- Taconic Biosciences, Cologne, Germany; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology and Stem Cell Program, Children's Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA, USA
| | - Robert Piskol
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Gokul Ramaswami
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Alistair M Chalk
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
| | - Paul D Kingsley
- Center for Pediatric Biomedical Research, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Vijay G Sankaran
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology and Stem Cell Program, Children's Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA, USA
| | - Meaghan Wall
- Victorian Cancer Cytogenetics Service, St. Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Louise E Purton
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
| | - Peter H Seeburg
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - James Palis
- Center for Pediatric Biomedical Research, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Stuart H Orkin
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology and Stem Cell Program, Children's Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Boston, MA, USA
| | - Jun Lu
- Department of Genetics and Yale Stem Cell Center, Yale University, New Haven, CT, USA
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Carl R Walkley
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia.
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281
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Innate immunity against hepatitis C virus. Curr Opin Immunol 2016; 42:98-104. [PMID: 27366996 DOI: 10.1016/j.coi.2016.06.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 06/09/2016] [Accepted: 06/15/2016] [Indexed: 12/24/2022]
Abstract
Hepatitis C virus (HCV) infection tends persistent and causes chronic liver diseases, including inflammation, cirrhosis and hepatocellular carcinoma. Innate immune responses triggered by HCV infection, particularly the production of interferons and pro-inflammatory cytokines, shape the early host antiviral defense, and orchestrate subsequent HCV-specific adaptive immunity. Host has evolved multifaceted means to sense HCV infection to induce innate immune responses, whereas HCV has also developed elaborate strategies to evade immune attack. Recent studies in the field have provided many new insights into the interplay of HCV and innate immunity. In this review, we summarized these recent advances, focusing on pathogen recognition by innate sensors, newly discovered anti-HCV innate effectors and new viral strategies to evade innate immunity.
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282
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Abstract
The co-evolution of viruses with their hosts has led to the emergence of viral pathogens that are adept at evading or actively suppressing host immunity. Pattern recognition receptors (PRRs) are key components of antiviral immunity that detect conserved molecular features of viral pathogens and initiate signalling that results in the expression of antiviral genes. In this Review, we discuss the strategies that viruses use to escape immune surveillance by key intracellular sensors of viral RNA or DNA, with a focus on RIG-I-like receptors (RLRs), cyclic GMP-AMP synthase (cGAS) and interferon-γ (IFNγ)-inducible protein 16 (IFI16). Such viral strategies include the sequestration or modification of viral nucleic acids, interference with specific post-translational modifications of PRRs or their adaptor proteins, the degradation or cleavage of PRRs or their adaptors, and the sequestration or relocalization of PRRs. An understanding of viral immune-evasion mechanisms at the molecular level may guide the development of vaccines and antivirals.
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Affiliation(s)
- Ying Kai Chan
- grid.38142.3c000000041936754XDepartment of Microbiology and Immunobiology, Harvard Medical School, Boston, 02115 Massachusetts USA
| | - Michaela U. Gack
- grid.170205.10000 0004 1936 7822Department of Microbiology, The University of Chicago, Chicago, 60637 Illinois USA
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283
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Buers I, Nitschke Y, Rutsch F. Novel interferonopathies associated with mutations in RIG-I like receptors. Cytokine Growth Factor Rev 2016; 29:101-7. [PMID: 26993858 DOI: 10.1016/j.cytogfr.2016.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Type I interferonopathies are a relatively new class of inherited autoimmune disorders associated with an inborn elevated interferon response. Activation of cytosolic receptors which recognize viral double stranded RNA including the RIG-I (retinoic acid-inducible gene I) like receptors RIG-I and MDA5 (melanoma differentiation-associated gene 5) has been shown to induce the transcription of type I interferon genes. Within recent years, with the help of next generation sequencing techniques in syndromic families, mutations in the genes encoding for RIG-I and MDA5 have been identified to cause rare diseases including Aicardi-Goutières syndrome, Systemic Lupus Erythematosus in certain individuals as well as classic and atypical Singleton-Merten syndrome. Patients carrying mono-allelic mutations in MDA5 and RIG-I show constitutive activation of the RIG-I receptors and downstream signalling associated with increased type I interferon production. Although differing in the degree of phenotypic expression and severity, the phenotype of these "novel" diseases shows a considerable overlap reflecting their common pathogenetic pathway.
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Affiliation(s)
- Insa Buers
- Department of General Pediatrics, Muenster University Children's Hospital, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster, Germany.
| | - Yvonne Nitschke
- Department of General Pediatrics, Muenster University Children's Hospital, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster, Germany.
| | - Frank Rutsch
- Department of General Pediatrics, Muenster University Children's Hospital, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster, Germany.
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284
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Oshiumi H, Kouwaki T, Seya T. Accessory Factors of Cytoplasmic Viral RNA Sensors Required for Antiviral Innate Immune Response. Front Immunol 2016; 7:200. [PMID: 27252702 PMCID: PMC4879126 DOI: 10.3389/fimmu.2016.00200] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/09/2016] [Indexed: 12/18/2022] Open
Abstract
Type I interferon (IFN) induces many antiviral factors in host cells. RIG-I-like receptors (RLRs) are cytoplasmic viral RNA sensors that trigger the signal to induce the innate immune response that includes type I IFN production. RIG-I and MDA5 are RLRs that form nucleoprotein filaments along viral double-stranded RNA, resulting in the activation of MAVS adaptor molecule. The MAVS protein forms a prion-like aggregation structure, leading to type I IFN production. RIG-I and MDA5 undergo post-translational modification. TRIM25 and Riplet ubiquitin ligases deliver a K63-linked polyubiquitin moiety to the RIG-I N-terminal caspase activation and recruitment domains (CARDs) and C-terminal region; the polyubiquitin chain then stabilizes the two-CARD tetramer structure required for MAVS assembly. MDA5 activation is regulated by phosphorylation. RIOK3 is a protein kinase that phosphorylates the MDA5 protein in a steady state, and PP1α/γ dephosphorylate this protein, resulting in its activation. RIG-I and MDA5 require cytoplasmic RNA helicases for their efficient activation. LGP2, another RLR, is an RNA helicase involved in RLR signaling. This protein does not possess N-terminal CARDs and, thus, cannot trigger downstream signaling by itself. Recent studies have revealed that this protein modulates MDA5 filament formation, resulting in enhanced type I IFN production. Several other cytoplasmic RNA helicases are involved in RLR signaling. DDX3, DHX29, DHX36, and DDX60 RNA helicases have been reported to be involved in RLR-mediated type I IFN production after viral infection. However, the underlying mechanism is largely unknown. Future studies are required to reveal the role of RNA helicases in the RLR signaling pathway.
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Affiliation(s)
- Hiroyuki Oshiumi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kumamoto, Japan
| | - Takahisa Kouwaki
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Tsukasa Seya
- Department of Microbiology and Immunology, Graduate School of Medicine, Hokkaido University , Sapporo, Hokkaido , Japan
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285
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Bang BR, Elmasry S, Saito T. Organ system view of the hepatic innate immunity in HCV infection. J Med Virol 2016; 88:2025-2037. [PMID: 27153233 DOI: 10.1002/jmv.24569] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2016] [Indexed: 12/12/2022]
Abstract
An orchestration of innate and adaptive immunity determines the infection outcome and whether the host achieves clearance or allows the pathogen to establish persistent infection. The robust activation of the innate immune response plays the most critical role in both limiting viral replication and halting the spread of the pathogen immediately after infection. The magnitude of innate immune activation is coupled with the efficient mounting of the adaptive immunity. Although immunity against HCV infection is known to be inadequate as most cases transitions to chronicity, approximately 25% of acute infection cases result in spontaneous clearance. The exact immune mechanisms that govern the infection outcome remain largely unknown; recent discoveries suggest that the innate immune system facilitates this event. Both infected hepatocytes and local innate immune cells trigger the front line defense program of the liver as well as the recruitment of diverse adaptive immune cells to the site of infection. Although hepatocyte is the target of HCV infection, nearly all cell types that exist in the liver are involved in the innate defense and contribute to the pathophysiology of hepatic inflammation. The main focus of this comprehensive review is to discuss the current knowledge on how each hepatic cell type contributes to the organ system level innate immunity against HCV infection as well as interplays with the viral evasion program. Furthermore, this review article also aims to synchronize the observations from both molecular biological studies and clinical studies with the ultimate goal of improving our understanding of HCV mediated hepatitis. J. Med. Virol. 88:2025-2037, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Bo-Ram Bang
- Division of Gastrointestinal and Liver Diseases, Department of Medicine, USC Research Center for Liver Diseases, University of Southern California, Keck School of Medicine, Los Angeles, California
| | - Sandra Elmasry
- Division of Gastrointestinal and Liver Diseases, Department of Medicine, USC Research Center for Liver Diseases, University of Southern California, Keck School of Medicine, Los Angeles, California
| | - Takeshi Saito
- Division of Gastrointestinal and Liver Diseases, Department of Medicine, USC Research Center for Liver Diseases, University of Southern California, Keck School of Medicine, Los Angeles, California. .,Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California. .,Department of Pathology, University of Southern California, Keck School of Medicine, Los Angeles, California.
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286
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Ahmad S, Hur S. Helicases in Antiviral Immunity: Dual Properties as Sensors and Effectors. Trends Biochem Sci 2016; 40:576-585. [PMID: 26410598 DOI: 10.1016/j.tibs.2015.08.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 01/01/2023]
Abstract
Many helicases have a unique ability to couple cognate RNA binding to ATP hydrolysis, which can induce a large conformational change that affects its interaction with RNA, position along RNA, or oligomeric state. A growing number of these helicases contribute to the innate immune system, either as sensors that detect foreign nucleic acids and/or as effectors that directly participate in the clearance of such foreign species. In this review, we discuss a few examples, including retinoic acid-inducible gene-I (RIG-I), melanoma differentiation-associated gene 5 (MDA5), and Dicer, focusing on their dual functions as both sensors and effectors. We will also discuss the closely related, but less understood, helicases, laboratory of genetics and physiology 2 (LGP2) and Dicer-related helicase-1 and -3 (DRH-1 and -3).
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Affiliation(s)
- Sadeem Ahmad
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
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287
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The role of RNA editing by ADAR1 in prevention of innate immune sensing of self-RNA. J Mol Med (Berl) 2016; 94:1095-1102. [PMID: 27044320 DOI: 10.1007/s00109-016-1416-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/16/2016] [Accepted: 03/24/2016] [Indexed: 12/25/2022]
Abstract
The innate immune system is the first line of the cellular defence against invading pathogens. A critical component of this defence is the capacity to discriminate foreign RNA molecules, which are distinct from most cellular RNAs in structure and/or modifications. However, a series of rare autoimmune/autoinflammatory diseases in humans highlight the propensity for the innate immune sensing system to be activated by endogenous cellular double-stranded RNAs (dsRNAs), underscoring the fine line between distinguishing self from non-self. The RNA editing enzyme ADAR1 has recently emerged as a key regulator that prevents innate immune pathway activation, principally the cytosolic dsRNA sensor MDA5, from inducing interferon in response to double-stranded RNA structures within endogenous RNAs. Adenosine-to-Inosine RNA editing by ADAR1 is proposed to destabilise duplexes formed from inverted repetitive elements within RNAs, which appear to prevent MDA5 from sensing these RNA as virus-like in the cytoplasm. Aberrant activation of these pathways has catastrophic effects at both a cellular and organismal level, contributing to one of the causes of the conditions collectively known as the type I interferonopathies.
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288
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Sanchez David RY, Combredet C, Sismeiro O, Dillies MA, Jagla B, Coppée JY, Mura M, Guerbois Galla M, Despres P, Tangy F, Komarova AV. Comparative analysis of viral RNA signatures on different RIG-I-like receptors. eLife 2016; 5:e11275. [PMID: 27011352 PMCID: PMC4841775 DOI: 10.7554/elife.11275] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 03/24/2016] [Indexed: 12/17/2022] Open
Abstract
The RIG-I-like receptors (RLRs) play a major role in sensing RNA virus infection to initiate and modulate antiviral immunity. They interact with particular viral RNAs, most of them being still unknown. To decipher the viral RNA signature on RLRs during viral infection, we tagged RLRs (RIG-I, MDA5, LGP2) and applied tagged protein affinity purification followed by next-generation sequencing (NGS) of associated RNA molecules. Two viruses with negative- and positive-sense RNA genome were used: measles (MV) and chikungunya (CHIKV). NGS analysis revealed that distinct regions of MV genome were specifically recognized by distinct RLRs: RIG-I recognized defective interfering genomes, whereas MDA5 and LGP2 specifically bound MV nucleoprotein-coding region. During CHIKV infection, RIG-I associated specifically to the 3' untranslated region of viral genome. This study provides the first comparative view of the viral RNA ligands for RIG-I, MDA5 and LGP2 in the presence of infection.
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Affiliation(s)
- Raul Y Sanchez David
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS UMR-3569, Paris, France
- Ecole doctorale, Biochimie, Biothérapies, Biologie Moléculaire et Infectiologie (B3MI), Université Paris Diderot - Paris 7, Paris, France
| | - Chantal Combredet
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS UMR-3569, Paris, France
| | - Odile Sismeiro
- Transcriptome and Epigenome, BioMics Pole, Center for Innovation and Technological Research, Institut Pasteur, Paris, France
| | - Marie-Agnès Dillies
- Transcriptome and Epigenome, BioMics Pole, Center for Innovation and Technological Research, Institut Pasteur, Paris, France
| | - Bernd Jagla
- Transcriptome and Epigenome, BioMics Pole, Center for Innovation and Technological Research, Institut Pasteur, Paris, France
| | - Jean-Yves Coppée
- Transcriptome and Epigenome, BioMics Pole, Center for Innovation and Technological Research, Institut Pasteur, Paris, France
| | - Marie Mura
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS UMR-3569, Paris, France
- Unité Interactions Hôte-Agents Pathogens, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | | | - Philippe Despres
- Technology Platform CYROI, University of Reunion Island, Saint-Clotilde, France
| | - Frédéric Tangy
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS UMR-3569, Paris, France
| | - Anastassia V Komarova
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS UMR-3569, Paris, France
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289
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Radoshevich L, Dussurget O. Cytosolic Innate Immune Sensing and Signaling upon Infection. Front Microbiol 2016; 7:313. [PMID: 27014235 PMCID: PMC4789553 DOI: 10.3389/fmicb.2016.00313] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 02/26/2016] [Indexed: 12/13/2022] Open
Abstract
Cytosolic sensing of pathogens is essential to a productive immune response. Recent reports have emphasized the importance of signaling platforms emanating from organelles and cytosolic sensors, particularly during the response to intracellular pathogens. Here, we highlight recent discoveries identifying the key mediators of nucleic acid and cyclic nucleotide sensing and discuss their importance in host defense. This review will also cover strategies evolved by pathogens to manipulate these pathways.
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Affiliation(s)
- Lilliana Radoshevich
- Unité des Interactions Bactéries-Cellules, Institut PasteurParis, France; Institut National de la Santé et de la Recherche Médicale, U604Paris, France; Institut National de la Recherche Agronomique, USC2020Paris, France
| | - Olivier Dussurget
- Unité des Interactions Bactéries-Cellules, Institut PasteurParis, France; Institut National de la Santé et de la Recherche Médicale, U604Paris, France; Institut National de la Recherche Agronomique, USC2020Paris, France; Cellule Pasteur, Université Paris Diderot, Sorbonne Paris CitéParis, France
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290
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Yoneyama M, Jogi M, Onomoto K. Regulation of antiviral innate immune signaling by stress-induced RNA granules. J Biochem 2016; 159:279-86. [PMID: 26748340 PMCID: PMC4763080 DOI: 10.1093/jb/mvv122] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 09/24/2015] [Indexed: 12/17/2022] Open
Abstract
Activation of antiviral innate immunity is triggered by cellular pattern recognition receptors. Retinoic acid inducible gene-I (RIG-I)-like receptors (RLRs) detect viral non-self RNA in cytoplasm of virus-infected cells and play a critical role in the clearance of the invaded viruses through production of antiviral cytokines. Among the three known RLRs, RIG-I and melanoma differentiation-associated gene 5 recognize distinct non-self signatures of viral RNA and activate antiviral signaling. Recent reports have clearly described the molecular machinery underlying the activation of RLRs and interactions with the downstream adaptor, mitochondrial antiviral signaling protein (MAVS). RLRs and MAVS are thought to form large multimeric filaments around cytoplasmic organelles depending on the presence of Lys63-linked ubiquitin chains. Furthermore, RLRs have been shown to localize to stress-induced ribonucleoprotein aggregate known as stress granules and utilize them as a platform for recognition/activation of signaling. In this review, we will focus on the current understanding of RLR-mediated signal activation and the interactions with stress-induced RNA granules.
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Affiliation(s)
- Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan
| | - Michihiko Jogi
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan
| | - Koji Onomoto
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan
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291
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Pham AM, Santa Maria FG, Lahiri T, Friedman E, Marié IJ, Levy DE. PKR Transduces MDA5-Dependent Signals for Type I IFN Induction. PLoS Pathog 2016; 12:e1005489. [PMID: 26939124 PMCID: PMC4777437 DOI: 10.1371/journal.ppat.1005489] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 02/11/2016] [Indexed: 12/13/2022] Open
Abstract
Sensing invading pathogens early in infection is critical for establishing host defense. Two cytosolic RIG-like RNA helicases, RIG-I and MDA5, are key to type I interferon (IFN) induction in response to viral infection. Mounting evidence suggests that another viral RNA sensor, protein kinase R (PKR), may also be critical for IFN induction during infection, although its exact contribution and mechanism of action are not completely understood. Using PKR-deficient cells, we found that PKR was required for type I IFN induction in response to infection by vaccinia virus lacking the PKR antagonist E3L (VVΔE3L), but not by Sendai virus or influenza A virus lacking the IFN-antagonist NS1 (FluΔNS1). IFN induction required the catalytic activity of PKR, but not the phosphorylation of its principal substrate, eIF2α, or the resulting inhibition of host translation. In the absence of PKR, IRF3 nuclear translocation was impaired in response to MDA5 activators, VVΔE3L and encephalomyocarditis virus, but not during infection with a RIG-I-activating virus. Interestingly, PKR interacted with both RIG-I and MDA5; however, PKR was only required for MDA5-mediated, but not RIG-I-mediated, IFN production. Using an artificially activated form of PKR, we showed that PKR activity alone was sufficient for IFN induction. This effect required MAVS and correlated with IRF3 activation, but no longer required MDA5. Nonetheless, PKR activation during viral infection was enhanced by MDA5, as virus-stimulated catalytic activity was impaired in MDA5-null cells. Taken together, our data describe a critical and non-redundant role for PKR following MDA5, but not RIG-I, activation to mediate MAVS-dependent induction of type I IFN through a kinase-dependent mechanism.
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Affiliation(s)
- Alissa M. Pham
- Departments of Pathology and Microbiology and NYU Cancer Institute, NYU School of Medicine, New York, New York, United States of America
| | - Felicia Gilfoy Santa Maria
- Departments of Pathology and Microbiology and NYU Cancer Institute, NYU School of Medicine, New York, New York, United States of America
| | - Tanaya Lahiri
- Departments of Pathology and Microbiology and NYU Cancer Institute, NYU School of Medicine, New York, New York, United States of America
| | - Eugene Friedman
- Departments of Pathology and Microbiology and NYU Cancer Institute, NYU School of Medicine, New York, New York, United States of America
| | - Isabelle J. Marié
- Departments of Pathology and Microbiology and NYU Cancer Institute, NYU School of Medicine, New York, New York, United States of America
| | - David E. Levy
- Departments of Pathology and Microbiology and NYU Cancer Institute, NYU School of Medicine, New York, New York, United States of America
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292
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Oshiumi H, Mifsud EJ, Daito T. Links between recognition and degradation of cytoplasmic viral RNA in innate immune response. Rev Med Virol 2016; 26:90-101. [PMID: 26643446 DOI: 10.1002/rmv.1865] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/21/2015] [Accepted: 11/01/2015] [Indexed: 12/24/2022]
Abstract
Recognition and degradation of viral RNA are essential for antiviral innate immune responses. Cytoplasmic viral RNA is recognized by retinoic acid-inducible gene I (RIG-I)-like receptors, which trigger type I interferon (IFN) production. Secreted type I IFN activates ubiquitously expressed type I IFN receptor and induces IFN-stimulated genes (ISGs). To suppress viral replication, several nucleases degrade viral RNA. RNase L is an ISG with endonuclease activity that degrades viral RNA, producing small RNA that activates RIG-I, resulting in the amplification of type I IFN production. Moreover, recent studies have elucidated novel links between viral RNA recognition and degradation. The RNA exosome is a protein complex that includes nucleases and is essential for host and viral RNA decay. Although the small RNAs produced by the RNA exosome do not activate RIG-I, several accessory factors of the RNA exosome promote RIG-I activation. Zinc-finger antiviral protein (ZAP) is an accessory factor that recognizes viral RNA and promotes viral RNA degradation via the RNA exosome. ZAPS is an alternative splicing form of ZAP and promotes RIG-I oligomerization and ATPase activity, resulting in RIG-I activation. DDX60 is another cofactor involved in the viral RNA degradation via the RNA exosome. The DDX60 protein promotes RIG-I signaling in a cell-type specific manner. These observations imply that viral RNA degradation and recognition are linked to each other. In this review, I discuss the links between recognition and degradation of viral RNA.
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Affiliation(s)
- Hiroyuki Oshiumi
- Laboratory for Biologics Development, Research Center for Zoonosis Control, GI-CoRE Global Station for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Edin J Mifsud
- Laboratory for Biologics Development, Research Center for Zoonosis Control, GI-CoRE Global Station for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Takuji Daito
- Laboratory for Biologics Development, Research Center for Zoonosis Control, GI-CoRE Global Station for Zoonosis Control, Hokkaido University, Sapporo, Japan
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293
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Pestal K, Funk CC, Snyder JM, Price ND, Treuting PM, Stetson DB. Isoforms of RNA-Editing Enzyme ADAR1 Independently Control Nucleic Acid Sensor MDA5-Driven Autoimmunity and Multi-organ Development. Immunity 2016; 43:933-44. [PMID: 26588779 DOI: 10.1016/j.immuni.2015.11.001] [Citation(s) in RCA: 343] [Impact Index Per Article: 42.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/28/2015] [Accepted: 10/08/2015] [Indexed: 02/07/2023]
Abstract
Mutations in ADAR, which encodes the ADAR1 RNA-editing enzyme, cause Aicardi-Goutières syndrome (AGS), a severe autoimmune disease associated with an aberrant type I interferon response. How ADAR1 prevents autoimmunity remains incompletely defined. Here, we demonstrate that ADAR1 is a specific and essential negative regulator of the MDA5-MAVS RNA sensing pathway. Moreover, we uncovered a MDA5-MAVS-independent function for ADAR1 in the development of multiple organs. We showed that the p150 isoform of ADAR1 uniquely regulated the MDA5 pathway, whereas both the p150 and p110 isoforms contributed to development. Abrupt deletion of ADAR1 in adult mice revealed that both of these functions were required throughout life. Our findings delineate genetically separable roles for both ADAR1 isoforms in vivo, with implications for the human diseases caused by ADAR mutations.
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Affiliation(s)
- Kathleen Pestal
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Cory C Funk
- Institute for Systems Biology, Seattle, WA 98195, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
| | | | - Piper M Treuting
- Department of Comparative Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Daniel B Stetson
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA.
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294
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He Y, Xie Z, Dai J, Cao Y, Hou J, Zheng Y, Wei T, Mo M, Wei P. Responses of the Toll-like receptor and melanoma differentiation-associated protein 5 signaling pathways to avian infectious bronchitis virus infection in chicks. Virol Sin 2016; 31:57-68. [PMID: 26920710 PMCID: PMC7090632 DOI: 10.1007/s12250-015-3696-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/27/2016] [Indexed: 12/22/2022] Open
Abstract
Avian infectious bronchitis virus (IBV) is a Gammacoronavirus in the family Coronaviridae and causes highly contagious respiratory disease in chickens. Innate immunity plays significant roles in host defense against IBV. Here, we explored the interaction between IBV and the host innate immune system. Severe histopathological lesions were observed in the tracheal mucosa at 3-5 days post inoculation (dpi) and in the kidney at 8 dpi, with heavy viral loads at 1-11 and 1-28 dpi, respectively. The expression of mRNAs encoding Toll-like receptor (TLR) 3 and TLR7 were upregulated at 3-8 dpi, and that of TIR-domain-containing adapter-inducing interferon (IFN) β (TRIF) was upregulated at 21 dpi in the trachea and kidney. Myeloid differentiation primary response protein 88 (MyD88) was upregulated in the trachea during early infection. Tumor necrosis factor receptor-associated factor (TRAF) 3 and TRAF6 were upregulated expression in both tissues. Moreover, melanoma differentiation-associated protein 5 (MDA5), laboratory of genetics and physiology 2 (LGP2), stimulator of IFN genes (STING), and mitochondrial antiviral signaling protein (MAVS), as well as TANK binding kinase 1 (TBK1), inhibitor of kappaB kinase (IKK) ε, IKKα, IKKβ, IFN regulatory factor (IRF) 7, nuclear factor of kappaB (NF-ĸB), IFN-α, IFN-β, various interleukins(ILs), and macrophage inflammatory protein-1β (MIP-1β) were significantly upregulated in the trachea and downregulated in the kidney. These results suggested that the TLR and MDA5 signaling pathways and innate immune cytokine were induced after IBV infection. Additionally, consistent responses to IBV infection were observed during early infection, with differential and complicated responses in the kidney.![]()
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Affiliation(s)
- Yining He
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Zhiwen Xie
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Jinglong Dai
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Yanjie Cao
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Jinlian Hou
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Yansheng Zheng
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Tianchao Wei
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Meilan Mo
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China.
| | - Ping Wei
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China.
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295
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Yu X, Wang H, Li X, Guo C, Yuan F, Fisher PB, Wang XY. Activation of the MDA-5-IPS-1 Viral Sensing Pathway Induces Cancer Cell Death and Type I IFN-Dependent Antitumor Immunity. Cancer Res 2016; 76:2166-76. [PMID: 26893477 DOI: 10.1158/0008-5472.can-15-2142] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 02/04/2016] [Indexed: 01/08/2023]
Abstract
Melanoma differentiation-associated gene 5 (MDA-5, IFIH1), a cytosolic innate pattern recognition receptor, functions as a first line of defense against viral infection by sensing double-stranded RNA. Ectopic expression of MDA-5 has been shown to induce cancer cell death, but the mechanism of action by which MDA-5 exerts these cytotoxic effects is unclear. Here, we demonstrate that ectopic expression of MDA-5 via replication-incompetent adenovirus (Ad.Mda-5) initiates multiple signaling cascades, culminating in cytotoxicity and type I IFN production in mouse and human prostate cancer cells. This intrinsic dual activity of MDA-5 required the adaptor protein IFNβ promoter stimulator 1 (IPS-1, MAVS) and could be functionally uncoupled. MDA-5 lacking N-terminal caspase recruitment domains (CARD) engaged an intracellular death program in cancer cells but was unable to efficiently stimulate the expression of IFNβ. In contrast to cancer cells susceptible to MDA-5-mediated cytotoxicity, normal cells were highly resistant and instead developed a robust type I IFN response. Strikingly, intratumoral delivery of Ad.Mda-5 led to regression of preestablished prostate cancers and development of long-lasting antitumor immune memory, which was primarily attributed to the activation of tumor-reactive cytotoxic T lymphocytes and/or natural killer cells. Using the CARD-truncated MDA-5 mutant, silencing of IPS-1, and antibody blockade of the IFNα/β receptor, we further demonstrate that type I IFN signaling was crucial for in situ MDA-5-induced protective antitumor immunity. Therefore, deliberately targeting the evolutionarily conserved MDA-5-IPS-1 antiviral pathway in tumors can provoke parallel tumoricidal and immunostimulatory effects that bridge innate and adaptive immune responses for the therapeutic treatment of cancer. Cancer Res; 76(8); 2166-76. ©2016 AACR.
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Affiliation(s)
- Xiaofei Yu
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Hongxia Wang
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Xia Li
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Chunqing Guo
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Fang Yuan
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Paul B Fisher
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia. VCU Institute of Molecular Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia. VCU Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
| | - Xiang-Yang Wang
- Department of Human & Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia. VCU Institute of Molecular Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia. VCU Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
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296
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Sohn J, Hur S. Filament assemblies in foreign nucleic acid sensors. Curr Opin Struct Biol 2016; 37:134-44. [PMID: 26859869 DOI: 10.1016/j.sbi.2016.01.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/20/2016] [Accepted: 01/21/2016] [Indexed: 12/24/2022]
Abstract
Helical filamentous assembly is ubiquitous in biology, but was only recently realized to be broadly employed in the innate immune system of vertebrates. Accumulating evidence suggests that the filamentous assemblies and helical oligomerization play important roles in detection of foreign nucleic acids and activation of the signaling pathways to produce antiviral and inflammatory mediators. In this review, we focus on the helical assemblies observed in the signaling pathways of RIG-I-like receptors (RLRs) and AIM2-like receptors (ALRs). We describe ligand-dependent oligomerization of receptor, receptor-dependent oligomerization of signaling adaptor molecules, and their functional implications and regulations.
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Affiliation(s)
- Jungsan Sohn
- Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Sun Hur
- Harvard Medical School, Boston, MA, USA.
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297
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Leung DW, Amarasinghe GK. When your cap matters: structural insights into self vs non-self recognition of 5' RNA by immunomodulatory host proteins. Curr Opin Struct Biol 2016; 36:133-41. [PMID: 26916433 PMCID: PMC5218996 DOI: 10.1016/j.sbi.2016.02.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 02/04/2016] [Indexed: 12/13/2022]
Abstract
Cytosolic recognition of viral RNA is important for host innate immune responses. Differential recognition of self vs non-self RNA is a considerable challenge as the inability to differentiate may trigger aberrant immune responses. Recent work identified the composition of the RNA 5', including the 5' cap and its methylation state, as an important determinant of recognition by the host. Recent studies have advanced our understanding of the modified 5' RNA recognition and viral antagonism of RNA receptors. Here, we will discuss RIG-I and IFIT proteins as examples of host proteins that detect dsRNA and ssRNA, respectively.
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Affiliation(s)
- Daisy W Leung
- Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St Louis, MO 63110, United States.
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St Louis, MO 63110, United States.
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298
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Wong LYR, Lui PY, Jin DY. A molecular arms race between host innate antiviral response and emerging human coronaviruses. Virol Sin 2016; 31:12-23. [PMID: 26786772 PMCID: PMC7090626 DOI: 10.1007/s12250-015-3683-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Accepted: 01/07/2016] [Indexed: 02/07/2023] Open
Abstract
Coronaviruses have been closely related with mankind for thousands of years. Communityacquired human coronaviruses have long been recognized to cause common cold. However, zoonotic coronaviruses are now becoming more a global concern with the discovery of highly pathogenic severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronaviruses causing severe respiratory diseases. Infections by these emerging human coronaviruses are characterized by less robust interferon production. Treatment of patients with recombinant interferon regimen promises beneficial outcomes, suggesting that compromised interferon expression might contribute at least partially to the severity of disease. The mechanisms by which coronaviruses evade host innate antiviral response are under intense investigations. This review focuses on the fierce arms race between host innate antiviral immunity and emerging human coronaviruses. Particularly, the host pathogen recognition receptors and the signal transduction pathways to mount an effective antiviral response against SARS and MERS coronavirus infection are discussed. On the other hand, the counter-measures evolved by SARS and MERS coronaviruses to circumvent host defense are also dissected. With a better understanding of the dynamic interaction between host and coronaviruses, it is hoped that insights on the pathogenesis of newly-identified highly pathogenic human coronaviruses and new strategies in antiviral development can be derived.![]()
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Affiliation(s)
- Lok-Yin Roy Wong
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Pak-Yin Lui
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China.
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299
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Takashima K, Oshiumi H, Takaki H, Matsumoto M, Seya T. RIOK3-mediated phosphorylation of MDA5 interferes with its assembly and attenuates the innate immune response. Cell Rep 2016; 11:192-200. [PMID: 25865883 DOI: 10.1016/j.celrep.2015.03.027] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 01/23/2015] [Accepted: 03/11/2015] [Indexed: 12/24/2022] Open
Abstract
MDA5 is a cytoplasmic viral double-stranded RNA (dsRNA) sensor and triggers type I interferon (IFN) production. MDA5 assembles along viral dsRNA, leading to the formation of an MDA5 filament required for activating the MAVS adaptor. A recent study has revealed that PP1α and PP1γ phosphatases are responsible for dephosphorylating MDA5 and are essential for its activation. Here, we identified RIO kinase 3 (RIOK3) as a protein kinase that phosphorylates the MDA5 C-terminal region. RIOK3 knockout strongly enhanced type I IFN and IFN-inducible gene expression following measles virus infection. Conversely, the ectopic expression of RIOK3 or a phosphomimetic MDA5-S828D mutation attenuated MDA5-mediated signaling. Moreover, RIOK3-mediated MDA5 phosphorylation impaired MDA5 multimer formation, indicating that MDA5 C-terminal phosphorylation interferes with MDA5 filament formation and suppresses its signaling. Our data revealed a regulatory mechanism underlying the activation of the cytoplasmic viral RNA sensor MDA5 in both uninfected and virus-infected cells.
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Structural basis for m7G recognition and 2'-O-methyl discrimination in capped RNAs by the innate immune receptor RIG-I. Proc Natl Acad Sci U S A 2016; 113:596-601. [PMID: 26733676 DOI: 10.1073/pnas.1515152113] [Citation(s) in RCA: 234] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
RNAs with 5'-triphosphate (ppp) are detected in the cytoplasm principally by the innate immune receptor Retinoic Acid Inducible Gene-I (RIG-I), whose activation triggers a Type I IFN response. It is thought that self RNAs like mRNAs are not recognized by RIG-I because 5'ppp is capped by the addition of a 7-methyl guanosine (m7G) (Cap-0) and a 2'-O-methyl (2'-OMe) group to the 5'-end nucleotide ribose (Cap-1). Here we provide structural and mechanistic basis for exact roles of capping and 2'-O-methylation in evading RIG-I recognition. Surprisingly, Cap-0 and 5'ppp double-stranded (ds) RNAs bind to RIG-I with nearly identical Kd values and activate RIG-I's ATPase and cellular signaling response to similar extents. On the other hand, Cap-0 and 5'ppp single-stranded RNAs did not bind RIG-I and are signaling inactive. Three crystal structures of RIG-I complexes with dsRNAs bearing 5'OH, 5'ppp, and Cap-0 show that RIG-I can accommodate the m7G cap in a cavity created through conformational changes in the helicase-motif IVa without perturbing the ppp interactions. In contrast, Cap-1 modifications abrogate RIG-I signaling through a mechanism involving the H830 residue, which we show is crucial for discriminating between Cap-0 and Cap-1 RNAs. Furthermore, m7G capping works synergistically with 2'-O-methylation to weaken RNA affinity by 200-fold and lower ATPase activity. Interestingly, a single H830A mutation restores both high-affinity binding and signaling activity with 2'-O-methylated dsRNAs. Our work provides new structural insights into the mechanisms of host and viral immune evasion from RIG-I, explaining the complexity of cap structures over evolution.
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