1
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Watkins JM, Burke JM. A closer look at mammalian antiviral condensates. Biochem Soc Trans 2024; 52:1393-1404. [PMID: 38778761 DOI: 10.1042/bst20231296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/01/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024]
Abstract
Several biomolecular condensates assemble in mammalian cells in response to viral infection. The most studied of these are stress granules (SGs), which have been proposed to promote antiviral innate immune signaling pathways, including the RLR-MAVS, the protein kinase R (PKR), and the OAS-RNase L pathways. However, recent studies have demonstrated that SGs either negatively regulate or do not impact antiviral signaling. Instead, the SG-nucleating protein, G3BP1, may function to perturb viral RNA biology by condensing viral RNA into viral-aggregated RNA condensates, thus explaining why viruses often antagonize G3BP1 or hijack its RNA condensing function. However, a recently identified condensate, termed double-stranded RNA-induced foci, promotes the activation of the PKR and OAS-RNase L antiviral pathways. In addition, SG-like condensates known as an RNase L-induced bodies (RLBs) have been observed during many viral infections, including SARS-CoV-2 and several flaviviruses. RLBs may function in promoting decay of cellular and viral RNA, as well as promoting ribosome-associated signaling pathways. Herein, we review these recent advances in the field of antiviral biomolecular condensates, and we provide perspective on the role of canonical SGs and G3BP1 during the antiviral response.
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Affiliation(s)
- J Monty Watkins
- Department of Molecular Medicine, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, U.S.A
- Department of Immunology and Microbiology, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, U.S.A
- Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL, U.S.A
| | - James M Burke
- Department of Molecular Medicine, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, U.S.A
- Department of Immunology and Microbiology, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, U.S.A
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2
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Yoneyama M, Kato H, Fujita T. Physiological functions of RIG-I-like receptors. Immunity 2024; 57:731-751. [PMID: 38599168 DOI: 10.1016/j.immuni.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/19/2024] [Accepted: 03/04/2024] [Indexed: 04/12/2024]
Abstract
RIG-I-like receptors (RLRs) are crucial for pathogen detection and triggering immune responses and have immense physiological importance. In this review, we first summarize the interferon system and innate immunity, which constitute primary and secondary responses. Next, the molecular structure of RLRs and the mechanism of sensing non-self RNA are described. Usually, self RNA is refractory to the RLR; however, there are underlying host mechanisms that prevent immune reactions. Studies have revealed that the regulatory mechanisms of RLRs involve covalent molecular modifications, association with regulatory factors, and subcellular localization. Viruses have evolved to acquire antagonistic RLR functions to escape the host immune reactions. Finally, the pathologies caused by the malfunction of RLR signaling are described.
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Affiliation(s)
- Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba, Japan; Division of Pandemic and Post-disaster Infectious Diseases, Research Institute of Disaster Medicine, Chiba University, Chiba, Japan
| | - Hiroki Kato
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Takashi Fujita
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany; Laboratory of Regulatory Information, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan.
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3
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Defourny KAY, Pei X, van Kuppeveld FJM, Nolte-T Hoen ENM. Picornavirus security proteins promote the release of extracellular vesicle enclosed viruses via the modulation of host kinases. PLoS Pathog 2024; 20:e1012133. [PMID: 38662794 DOI: 10.1371/journal.ppat.1012133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 05/07/2024] [Accepted: 03/18/2024] [Indexed: 05/08/2024] Open
Abstract
The discovery that extracellular vesicles (EVs) serve as carriers of virus particles calls for a reevaluation of the release strategies of non-enveloped viruses. Little is currently known about the molecular mechanisms that determine the release and composition of EVs produced by virus-infected cells, as well as conservation of these mechanisms among viruses. We previously described an important role for the Leader protein of the picornavirus encephalomyocarditis virus (EMCV) in the induction of virus-carrying EV subsets with distinct molecular and physical properties. EMCV L acts as a 'viral security protein' by suppressing host antiviral stress and type-I interferon (IFN) responses. Here, we tested the ability of functionally related picornavirus proteins of Theilers murine encephalitis virus (TMEV L), Saffold virus (SAFV L), and coxsackievirus B3 (CVB3 2Apro), to rescue EV and EV-enclosed virus release when introduced in Leader-deficient EMCV. We show that all viral security proteins tested were able to promote virus packaging in EVs, but that only the expression of EMCV L and CVB3 2Apro increased overall EV production. We provide evidence that one of the main antiviral pathways counteracted by this class of picornaviral proteins, i.e. the inhibition of PKR-mediated stress responses, affected EV and EV-enclosed virus release during infection. Moreover, we show that the enhanced capacity of the viral proteins EMCV L and CVB3 2Apro to promote EV-enclosed virus release is linked to their ability to simultaneously promote the activation of the stress kinase P38 MAPK. Taken together, we demonstrate that cellular stress pathways involving the kinases PKR and P38 are modulated by the activity of non-structural viral proteins to increase the release EV-enclosed viruses during picornavirus infections. These data shed new light on the molecular regulation of EV production in response to virus infection.
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Affiliation(s)
- Kyra A Y Defourny
- Infection Biology Section, Division of Infectious Diseases & Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Xinyi Pei
- Infection Biology Section, Division of Infectious Diseases & Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Frank J M van Kuppeveld
- Virology Section, Division of Infectious Diseases & Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Esther N M Nolte-T Hoen
- Infection Biology Section, Division of Infectious Diseases & Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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4
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Burke JM, Ratnayake OC, Watkins JM, Perera R, Parker R. G3BP1-dependent condensation of translationally inactive viral RNAs antagonizes infection. SCIENCE ADVANCES 2024; 10:eadk8152. [PMID: 38295168 PMCID: PMC10830107 DOI: 10.1126/sciadv.adk8152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 12/28/2023] [Indexed: 02/02/2024]
Abstract
G3BP1 is an RNA binding protein that condenses untranslating messenger RNAs into stress granules (SGs). G3BP1 is inactivated by multiple viruses and is thought to antagonize viral replication by SG-enhanced antiviral signaling. Here, we show that neither G3BP1 nor SGs generally alter the activation of innate immune pathways. Instead, we show that the RNAs encoded by West Nile virus, Zika virus, and severe acute respiratory syndrome coronavirus 2 are prone to G3BP1-dependent RNA condensation, which is enhanced by limiting translation initiation and correlates with the disruption of viral replication organelles and viral RNA replication. We show that these viruses counteract condensation of their RNA genomes by inhibiting the RNA condensing function of G3BP proteins, hijacking the RNA decondensing activity of eIF4A, and/or maintaining efficient translation. These findings argue that RNA condensation can function as an intrinsic antiviral mechanism, which explains why many viruses inactivate G3BP proteins and suggests that SGs may have arisen as a vestige of this antiviral mechanism.
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Affiliation(s)
- James M. Burke
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL 33458, USA
- Department of Immunology and Microbiology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL 33458, USA
| | - Oshani C. Ratnayake
- Center for Vector-Borne and Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
- Center for Metabolism of Infectious Diseases, Colorado State University, Fort Collins, CO 80523, USA
| | - J. Monty Watkins
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL 33458, USA
- Department of Immunology and Microbiology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL 33458, USA
- Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL 33438, USA
| | - Rushika Perera
- Center for Vector-Borne and Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
- Center for Metabolism of Infectious Diseases, Colorado State University, Fort Collins, CO 80523, USA
| | - Roy Parker
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
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5
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Sadasivan J, Hyrina A, DaSilva R, Jan E. An Insect Viral Protein Disrupts Stress Granule Formation in Mammalian Cells. J Mol Biol 2023; 435:168042. [PMID: 36898623 DOI: 10.1016/j.jmb.2023.168042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 02/23/2023] [Accepted: 03/02/2023] [Indexed: 03/12/2023]
Abstract
Stress granules (SGs) are cytosolic RNA-protein aggregates assembled during stress-induced translation arrest. Virus infection, in general, modulates and blocks SG formation. We previously showed that the model dicistrovirus Cricket paralysis virus (CrPV) 1A protein blocks stress granule formation in insect cells, which is dependent on a specific arginine 146 residue. CrPV-1A also inhibits SG formation in mammalian cells suggesting that this insect viral protein may be acting on a fundamental process that regulates SG formation. The mechanism underlying this process is not fully understood. Here, we show that overexpression of wild-type CrPV-1A, but not the CrPV-1A(R146A) mutant protein, inhibits distinct SG assembly pathways in HeLa cells. CrPV-1A mediated SG inhibition is independent of the Argonaute-2 (Ago-2) binding domain and the E3 ubiquitin ligase recruitment domain. CrPV-1A expression leads to nuclear poly(A)+ RNA accumulation and is correlated with the localization of CrPV-1A to the nuclear periphery. Finally, we show that the overexpression of CrPV-1A blocks FUS and TDP-43 granules, which are pathological hallmarks of neurodegenerative diseases. We propose a model whereby CrPV-1A expression in mammalian cells blocks SG formation by depleting cytoplasmic mRNA scaffolds via mRNA export inhibition. CrPV-1A provides a new molecular tool to study RNA-protein aggregates and potentially uncouple SG functions.
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Affiliation(s)
- Jibin Sadasivan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada. https://twitter.com/@jibin_sadasivan
| | - Anastasia Hyrina
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rachel DaSilva
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.
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6
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Moon S, Namkoong S. Ribonucleoprotein Granules: Between Stress and Transposable Elements. Biomolecules 2023; 13:1027. [PMID: 37509063 PMCID: PMC10377603 DOI: 10.3390/biom13071027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
Transposable elements (TEs) are DNA sequences that can transpose and replicate within the genome, leading to genetic changes that affect various aspects of host biology. Evolutionarily, hosts have also developed molecular mechanisms to suppress TEs at the transcriptional and post-transcriptional levels. Recent studies suggest that stress-induced formation of ribonucleoprotein (RNP) granules, including stress granule (SG) and processing body (P-body), can play a role in the sequestration of TEs to prevent transposition, suggesting an additional layer of the regulatory mechanism for TEs. RNP granules have been shown to contain factors involved in RNA regulation, including mRNA decay enzymes, RNA-binding proteins, and noncoding RNAs, which could potentially contribute to the regulation of TEs. Therefore, understanding the interplay between TEs and RNP granules is crucial for elucidating the mechanisms for maintaining genomic stability and controlling gene expression. In this review, we provide a brief overview of the current knowledge regarding the interplay between TEs and RNP granules, proposing RNP granules as a novel layer of the regulatory mechanism for TEs during stress.
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Affiliation(s)
- Sungjin Moon
- Department of Biological Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Sim Namkoong
- Department of Biochemistry, Kangwon National University, Chuncheon 24341, Republic of Korea
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7
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Vermeulen A, Takken FLW, Sánchez-Camargo VA. Translation Arrest: A Key Player in Plant Antiviral Response. Genes (Basel) 2023; 14:1293. [PMID: 37372472 DOI: 10.3390/genes14061293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/15/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
Plants evolved several mechanisms to protect themselves against viruses. Besides recessive resistance, where compatible host factors required for viral proliferation are absent or incompatible, there are (at least) two types of inducible antiviral immunity: RNA silencing (RNAi) and immune responses mounted upon activation of nucleotide-binding domain leucine-rich repeat (NLR) receptors. RNAi is associated with viral symptom recovery through translational repression and transcript degradation following recognition of viral double-stranded RNA produced during infection. NLR-mediated immunity is induced upon (in)direct recognition of a viral protein by an NLR receptor, triggering either a hypersensitive response (HR) or an extreme resistance response (ER). During ER, host cell death is not apparent, and it has been proposed that this resistance is mediated by a translational arrest (TA) of viral transcripts. Recent research indicates that translational repression plays a crucial role in plant antiviral resistance. This paper reviews current knowledge on viral translational repression during viral recovery and NLR-mediated immunity. Our findings are summarized in a model detailing the pathways and processes leading to translational arrest of plant viruses. This model can serve as a framework to formulate hypotheses on how TA halts viral replication, inspiring new leads for the development of antiviral resistance in crops.
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Affiliation(s)
- Annemarie Vermeulen
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - Frank L W Takken
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - Victor A Sánchez-Camargo
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, 1098 XH Amsterdam, The Netherlands
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8
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Paget M, Cadena C, Ahmad S, Wang HT, Jordan TX, Kim E, Koo B, Lyons SM, Ivanov P, tenOever B, Mu X, Hur S. Stress granules are shock absorbers that prevent excessive innate immune responses to dsRNA. Mol Cell 2023; 83:1180-1196.e8. [PMID: 37028415 PMCID: PMC10170497 DOI: 10.1016/j.molcel.2023.03.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 09/08/2022] [Accepted: 03/08/2023] [Indexed: 04/09/2023]
Abstract
Proper defense against microbial infection depends on the controlled activation of the immune system. This is particularly important for the RIG-I-like receptors (RLRs), which recognize viral dsRNA and initiate antiviral innate immune responses with the potential of triggering systemic inflammation and immunopathology. Here, we show that stress granules (SGs), molecular condensates that form in response to various stresses including viral dsRNA, play key roles in the controlled activation of RLR signaling. Without the SG nucleators G3BP1/2 and UBAP2L, dsRNA triggers excessive inflammation and immune-mediated apoptosis. In addition to exogenous dsRNA, host-derived dsRNA generated in response to ADAR1 deficiency is also controlled by SG biology. Intriguingly, SGs can function beyond immune control by suppressing viral replication independently of the RLR pathway. These observations thus highlight the multi-functional nature of SGs as cellular "shock absorbers" that converge on protecting cell homeostasis by dampening both toxic immune response and viral replication.
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Affiliation(s)
- Max Paget
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Cristhian Cadena
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sadeem Ahmad
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Hai-Tao Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Tristan X Jordan
- Department of Microbiology, New York University, Grossman School of Medicine, New York, NY 10016, USA
| | - Ehyun Kim
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Beechui Koo
- Morrisey School of Arts and Science, Boston College, Boston, MA 02467, USA
| | - Shawn M Lyons
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Division of Rheumatology, Inflammation, and Immunity, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Pavel Ivanov
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Division of Rheumatology, Inflammation, and Immunity, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Benjamin tenOever
- Department of Microbiology, New York University, Grossman School of Medicine, New York, NY 10016, USA
| | - Xin Mu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sun Hur
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
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9
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Corbet GA, Burke JM, Parker R. Nucleic acid-protein condensates in innate immune signaling. EMBO J 2023; 42:e111870. [PMID: 36178199 PMCID: PMC10068312 DOI: 10.15252/embj.2022111870] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/24/2022] [Accepted: 09/19/2022] [Indexed: 11/09/2022] Open
Abstract
The presence of foreign nucleic acids in the cytosol is a marker of infection. Cells have sensors, also known as pattern recognition receptors (PRRs), in the cytosol that detect foreign nucleic acid and initiate an innate immune response. Recent studies have reported the condensation of multiple PRRs including PKR, NLRP6, and cGAS, with their nucleic acid activators into discrete nucleoprotein assemblies. Nucleic acid-protein condensates form due to multivalent interactions and can create high local concentrations of components. The formation of PRR-containing condensates may alter the magnitude or timing of PRR activation. In addition, unique condensates form following RNase L activation or during paracrine signaling from virally infected cells that may play roles in antiviral defense. These observations suggest that condensate formation may be a conserved mechanism that cells use to regulate activation of the innate immune response and open an avenue for further investigation into the composition and function of these condensates. Here we review the nucleic acid-protein granules that are implicated in the innate immune response, discuss general consequences of condensate formation and signal transduction, as well as what outstanding questions remain.
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Affiliation(s)
- Giulia A Corbet
- Department of BiochemistryUniversity of ColoradoBoulderCOUSA
| | - James M Burke
- Department of BiochemistryUniversity of ColoradoBoulderCOUSA
- Present address:
Department of Molecular MedicineUniversity of Florida Scripps Biomedical ResearchJupiterFLUSA
| | - Roy Parker
- Department of BiochemistryUniversity of ColoradoBoulderCOUSA
- Howard Hughes Medical InstituteChevy ChaseMDUSA
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10
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Li W, Wang Y. Stress granules: potential therapeutic targets for infectious and inflammatory diseases. Front Immunol 2023; 14:1145346. [PMID: 37205103 PMCID: PMC10185834 DOI: 10.3389/fimmu.2023.1145346] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 04/12/2023] [Indexed: 05/21/2023] Open
Abstract
Eukaryotic cells are stimulated by external pressure such as that derived from heat shock, oxidative stress, nutrient deficiencies, or infections, which induce the formation of stress granules (SGs) that facilitates cellular adaptation to environmental pressures. As aggregated products of the translation initiation complex in the cytoplasm, SGs play important roles in cell gene expression and homeostasis. Infection induces SGs formation. Specifically, a pathogen that invades a host cell leverages the host cell translation machinery to complete the pathogen life cycle. In response, the host cell suspends translation, which leads to SGs formation, to resist pathogen invasion. This article reviews the production and function of SGs, the interaction between SGs and pathogens, and the relationship between SGs and pathogen-induced innate immunity to provide directions for further research into anti-infection and anti-inflammatory disease strategies.
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Affiliation(s)
- Wenyuan Li
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Yao Wang
- Department of Infectious Diseases, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
- *Correspondence: Yao Wang,
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11
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Guan Y, Wang Y, Fu X, Bai G, Li X, Mao J, Yan Y, Hu L. Multiple functions of stress granules in viral infection at a glance. Front Microbiol 2023; 14:1138864. [PMID: 36937261 PMCID: PMC10014870 DOI: 10.3389/fmicb.2023.1138864] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/08/2023] [Indexed: 03/05/2023] Open
Abstract
Stress granules (SGs) are distinct RNA granules induced by various stresses, which are evolutionarily conserved across species. In general, SGs act as a conservative and essential self-protection mechanism during stress responses. Viruses have a long evolutionary history and viral infections can trigger a series of cellular stress responses, which may interact with SG formation. Targeting SGs is believed as one of the critical and conservative measures for viruses to tackle the inhibition of host cells. In this systematic review, we have summarized the role of SGs in viral infection and categorized their relationships into three tables, with a particular focus on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Moreover, we have outlined several kinds of drugs targeting SGs according to different pathways, most of which are potentially effective against SARS-CoV-2. We believe this review would offer a new view for the researchers and clinicians to attempt to develop more efficacious treatments for virus infection, particularly for the treatment of SARS-CoV-2 infection.
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Affiliation(s)
- Yuelin Guan
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yan Wang
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Xudong Fu
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Zhejiang Laboratory for Systems and Precision Medicine, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Guannan Bai
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Xue Li
- Department of Big Data in Health Science School of Public Health and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jianhua Mao
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yongbin Yan
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, China
- *Correspondence: Yongbin Yan,
| | - Lidan Hu
- The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
- Lidan Hu,
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12
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Brownsword MJ, Locker N. A little less aggregation a little more replication: Viral manipulation of stress granules. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1741. [PMID: 35709333 PMCID: PMC10078398 DOI: 10.1002/wrna.1741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 01/31/2023]
Abstract
Recent exciting studies have uncovered how membrane-less organelles, also known as biocondensates, are providing cells with rapid response pathways, allowing them to re-organize their cellular contents and adapt to stressful conditions. Their assembly is driven by the phase separation of their RNAs and intrinsically disordered protein components into condensed foci. Among these, stress granules (SGs) are dynamic cytoplasmic biocondensates that form in response to many stresses, including activation of the integrated stress response or viral infections. SGs sit at the crossroads between antiviral signaling and translation because they concentrate signaling proteins and components of the innate immune response, in addition to translation machinery and stalled mRNAs. Consequently, they have been proposed to contribute to antiviral activities, and therefore are targeted by viral countermeasures. Equally, SGs components can be commandeered by viruses for their own efficient replication. Phase separation processes are an important component of the viral life cycle, for example, driving the assembly of replication factories or inclusion bodies. Therefore, in this review, we will outline the recent understanding of this complex interplay and tug of war between viruses, SGs, and their components. This article is categorized under: RNA in Disease and Development > RNA in Disease Translation > Regulation RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Matthew J. Brownsword
- Faculty of Health and Medical Sciences, School of Biosciences and MedicineUniversity of SurreyGuildfordSurreyUK
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, School of Biosciences and MedicineUniversity of SurreyGuildfordSurreyUK
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13
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Sadasivan J, Vlok M, Wang X, Nayak A, Andino R, Jan E. Targeting Nup358/RanBP2 by a viral protein disrupts stress granule formation. PLoS Pathog 2022; 18:e1010598. [PMID: 36455064 PMCID: PMC9746944 DOI: 10.1371/journal.ppat.1010598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 12/13/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
Viruses have evolved mechanisms to modulate cellular pathways to facilitate infection. One such pathway is the formation of stress granules (SG), which are ribonucleoprotein complexes that assemble during translation inhibition following cellular stress. Inhibition of SG assembly has been observed under numerous virus infections across species, suggesting a conserved fundamental viral strategy. However, the significance of SG modulation during virus infection is not fully understood. The 1A protein encoded by the model dicistrovirus, Cricket paralysis virus (CrPV), is a multifunctional protein that can bind to and degrade Ago-2 in an E3 ubiquitin ligase-dependent manner to block the antiviral RNA interference pathway and inhibit SG formation. Moreover, the R146 residue of 1A is necessary for SG inhibition and CrPV infection in both Drosophila S2 cells and adult flies. Here, we uncoupled CrPV-1A's functions and provide insight into its underlying mechanism for SG inhibition. CrPV-1A mediated inhibition of SGs requires the E3 ubiquitin-ligase binding domain and the R146 residue, but not the Ago-2 binding domain. Wild-type but not mutant CrPV-1A R146A localizes to the nuclear membrane which correlates with nuclear enrichment of poly(A)+ RNA. Transcriptome changes in CrPV-infected cells are dependent on the R146 residue. Finally, Nup358/RanBP2 is targeted and degraded in CrPV-infected cells in an R146-dependent manner and the depletion of Nup358 blocks SG formation. We propose that CrPV utilizes a multiprong strategy whereby the CrPV-1A protein interferes with a nuclear event that contributes to SG inhibition in order to promote infection.
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Affiliation(s)
- Jibin Sadasivan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marli Vlok
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Xinying Wang
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Arabinda Nayak
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Raul Andino
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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14
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Abstract
Mammalian cells respond to dsRNA in multiple manners. One key response to dsRNA is the activation of PKR, an eIF2α kinase, which triggers translational arrest and the formation of stress granules. However, the process of PKR activation in cells is not fully understood. In response to increased endogenous or exogenous dsRNA, we observed that PKR forms novel cytosolic condensates, referred to as dsRNA-induced foci (dRIFs). dRIFs contain dsRNA, form in proportion to dsRNA, and are enhanced by longer dsRNAs. dRIFs enrich several other dsRNA-binding proteins, including ADAR1, Stau1, NLRP1, and PACT. Strikingly, dRIFs correlate with and form before translation repression by PKR and localize to regions of cells where PKR activation is initiated. We hypothesize that dRIF formation is a mechanism that cells use to enhance the sensitivity of PKR activation in response to low levels of dsRNA or to overcome viral inhibitors of PKR activation.
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15
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Harapas CR, Idiiatullina E, Al-Azab M, Hrovat-Schaale K, Reygaerts T, Steiner A, Laohamonthonkul P, Davidson S, Yu CH, Booty L, Masters SL. Organellar homeostasis and innate immune sensing. Nat Rev Immunol 2022; 22:535-549. [PMID: 35197578 DOI: 10.1038/s41577-022-00682-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2022] [Indexed: 02/06/2023]
Abstract
A cell is delimited by numerous borders that define specific organelles. The walls of some organelles are particularly robust, such as in mitochondria or endoplasmic reticulum, but some are more fluid such as in phase-separated stress granules. Either way, all organelles can be damaged at times, leading their contents to leak out into the surrounding environment. Therefore, an elegant way to construct an innate immune defence system is to recognize host molecules that do not normally reside within a particular compartment. Here, we provide several examples where organellar homeostasis is lost, leading to the activation of a specific innate immune sensor; these include NLRP3 activation owing to a disrupted trans-Golgi network, Pyrin activation due to cytoskeletal damage, and cGAS-STING activation following the leakage of nuclear or mitochondrial DNA. Frequently, organelle damage is observed downstream of pathogenic infection but it can also occur in sterile settings as associated with auto-inflammatory disease. Therefore, understanding organellar homeostasis is central to efforts that will identify new innate immune pathways, and therapeutics that balance organellar homeostasis, or target the breakdown pathways that trigger innate immune sensors, could be useful treatments for infection and chronic inflammatory diseases.
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Affiliation(s)
- Cassandra R Harapas
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Elina Idiiatullina
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China
| | - Mahmoud Al-Azab
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China
| | - Katja Hrovat-Schaale
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Thomas Reygaerts
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Annemarie Steiner
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia.,Institute of Structural Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Pawat Laohamonthonkul
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Sophia Davidson
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Chien-Hsiung Yu
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Lee Booty
- Immunology Network, Immunology Research Unit, GSK, Stevenage, UK
| | - Seth L Masters
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia. .,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia. .,Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China.
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16
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Sun M, Wu S, Zhang X, Liu Z, Zhang L, Kang S, Liao J, Liu M, Qin Q, Wei J. Grouper TIA-1 functions as a crucial antiviral molecule against nervous necrosis virus infection. FISH & SHELLFISH IMMUNOLOGY 2022; 121:478-486. [PMID: 35085738 DOI: 10.1016/j.fsi.2022.01.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/21/2022] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
T-cell intracellular antigen (TIA)-1 is a prion-related RNA-binding protein involved in splicing and translational repression, and regulates translation in response to stress conditions by isolating target mRNAs in stress granules (SGs). However, little is known about the potential roles of fish TIA-1 and how it works in viral infection. In this study, the TIA-1 (EcTIA-1) homolog from orange-spotted grouper (Epinephelus coioides) was cloned and characterized. The open reading frame (ORF) sequence of EcTIA-1 encoded a 388 amino acid protein with predicted molecular mass of 42.73 kDa. EcTIA-1 contains three conserved domains of RNA recognition motif (RRM) that may interact with RNA via its second and third RRMs. Overexpression of EcTIA-1 inhibited red-spotted grouper nervous necrosis virus (RGNNV) replication and positively regulated interferon immune response, which was increased by knockdown of EcTIA-1. RGNNV induced formation of SGs in cells with EcTIA-1 overexpression. These results provide a novel insight into understanding the roles of fish TIA-1 in response to RNA viruses.
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Affiliation(s)
- Mengshi Sun
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Siting Wu
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Xin Zhang
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Zetian Liu
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Luhao Zhang
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Shaozhu Kang
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Jiaming Liao
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Mengke Liu
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China
| | - Qiwei Qin
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China; Guangdong Laboratory for Lingnan Modern Agriculture, PR China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, PR China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 528478, PR China.
| | - Jingguang Wei
- University Joint Laboratory of Guangdong Province, Hong Kong and Macao Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, PR China.
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17
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Wang C, Wang T, Duan L, Chen H, Hu R, Wang X, Jia Y, Chu Z, Liu H, Wang X, Zhang S, Xiao S, Wang J, Dang R, Yang Z. Evasion of Host Antiviral Innate Immunity by Paramyxovirus Accessory Proteins. Front Microbiol 2022; 12:790191. [PMID: 35173691 PMCID: PMC8841848 DOI: 10.3389/fmicb.2021.790191] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/22/2021] [Indexed: 01/01/2023] Open
Abstract
For efficient replication, viruses have developed multiple strategies to evade host antiviral innate immunity. Paramyxoviruses are a large family of enveloped RNA viruses that comprises diverse human and animal pathogens which jeopardize global public health and the economy. The accessory proteins expressed from the P gene by RNA editing or overlapping open reading frames (ORFs) are major viral immune evasion factors antagonizing type I interferon (IFN-I) production and other antiviral innate immune responses. However, the antagonistic mechanisms against antiviral innate immunity by accessory proteins differ among viruses. Here, we summarize the current understandings of immune evasion mechanisms by paramyxovirus accessory proteins, specifically how accessory proteins directly or indirectly target the adaptors in the antiviral innate immune signaling pathway to facilitate virus replication. Additionally, some cellular responses, which are also involved in viral replication, will be briefly summarized.
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18
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Deater M, Tamhankar M, Lloyd RE. TDRD3 is an antiviral restriction factor that promotes IFN signaling with G3BP1. PLoS Pathog 2022; 18:e1010249. [PMID: 35085371 PMCID: PMC8824378 DOI: 10.1371/journal.ppat.1010249] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 02/08/2022] [Accepted: 01/05/2022] [Indexed: 12/19/2022] Open
Abstract
Stress granules (SGs) are highly dynamic cytoplasmic foci that form in response to activation of the integrated stress response (ISR) that results in eIF2α phosphorylation and global translation shutdown. Stress granules, which are largely nucleated by G3BP1, serve as hubs for mRNA triage, but there is mounting evidence that they also perform cell signaling functions that are vital to cell survival, particularly during viral infection. We previously showed that SG formation leads to NFκB activation and JNK signaling and that this association may be due in part to G3BP1-dependent recruitment of PKR to SGs. Others have reported close associations between G3BP1 and various innate immune PRRs of the type 1 interferon signaling system, including RIG-I. We also reported SG assembly dynamics is dependent on the arginine-methylation status of G3BP1. Another protein that rapidly localizes to SGs, TDRD3, is a methyl reader protein that performs transcriptional activation and adaptor functions within the nucleus, but neither the mechanism nor its function in SGs is clear. Here, we present evidence that TDRD3 localizes to SGs partly based upon methylation potential of G3BP1. We also characterize granules that TDRD3 forms during overexpression and show that these granules can form in the absence of G3BP but also contain translation components found in canonical SGs. We also show for the first time that SGs recruit additional interferon effectors IRF3, IRF7, TBK1, and Sting, and provide evidence that TDRD3 may play a role in recruitment of these factors. We also present evidence that TDRD3 is a novel antiviral protein that is cleaved by enteroviral 2A proteinase. G3BP1 and TDRD3 knockdown in cells results in altered transcriptional regulation of numerous IFN effectors in complex modulatory patterns that are distinctive for G3BP1 and TDRD3. Overall, we describe a novel role of TDRD3 in innate immunity in which G3BP1 and TDRD3 may coordinate to play important roles in regulation of innate antiviral defenses. When cells are exposed to environmental stresses, such as oxidative stress and viral infection, it induces a cellular response leading to the formation of Stress Granules (SGs) composed of stalled translation initiation complexes (RNA-binding proteins and mRNA) and many other cellular proteins. SGs are also considered to be antiviral structures when they form during viral infection, but viruses can block SG formation to facilitate their survival, often by targeting the essential SG protein G3BP1. Here, we show that a methyl reader protein, TDRD3, localizes to SGs partly based on the methylation potential of G3BP1, and may play a role in the recruitment of innate immune factors to SGs. Further, when overexpressed, TDRD3 can also form SG-like structures independently of G3BP1. We also present evidence that TDRD3 is a novel antiviral protein. Virus replication is enhanced in the absence of both TDRD3 and G3BP1, and virus infection leads to cleavage of TDRD3 by the enterovirus proteinase 2A. Finally, we also show that depletion of TDRD3 and G3BP1 together in cells leads to restriction of transcriptional activation of numerous IFN effectors in response to dsRNA. The patterns of transcriptional activation are distinctive for G3BP1 and TDRD3. We conclude that TDRD3 may play a novel and important role in the regulation of the host antiviral response.
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Affiliation(s)
- Matthew Deater
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Manasi Tamhankar
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Richard E. Lloyd
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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19
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Abstract
Cells respond to viral infections through sensors that detect non-self-molecules, and through effectors, which can have direct antiviral activities or adapt cell physiology to limit viral infection and propagation. Eukaryotic translation initiation factor 2 alpha kinase 2, better known as PKR, acts as both a sensor and an effector in the response to viral infections. After sensing double-stranded RNA molecules in infected cells, PKR self-activates and majorly exerts its antiviral function by blocking the translation machinery and inducing apoptosis. The antiviral potency of PKR is emphasized by the number of strategies developed by viruses to antagonize the PKR pathway. In this review, we present an update on the diversity of such strategies, which range from preventing double-stranded RNA recognition upstream from PKR activation, to activating eIF2B downstream from PKR targets.
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Affiliation(s)
- Teresa Cesaro
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Thomas Michiels
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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20
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Embarc-Buh A, Francisco-Velilla R, Martinez-Salas E. RNA-Binding Proteins at the Host-Pathogen Interface Targeting Viral Regulatory Elements. Viruses 2021; 13:952. [PMID: 34064059 PMCID: PMC8224014 DOI: 10.3390/v13060952] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/10/2021] [Accepted: 05/17/2021] [Indexed: 12/16/2022] Open
Abstract
Viral RNAs contain the information needed to synthesize their own proteins, to replicate, and to spread to susceptible cells. However, due to their reduced coding capacity RNA viruses rely on host cells to complete their multiplication cycle. This is largely achieved by the concerted action of regulatory structural elements on viral RNAs and a subset of host proteins, whose dedicated function across all stages of the infection steps is critical to complete the viral cycle. Importantly, not only the RNA sequence but also the RNA architecture imposed by the presence of specific structural domains mediates the interaction with host RNA-binding proteins (RBPs), ultimately affecting virus multiplication and spreading. In marked difference with other biological systems, the genome of positive strand RNA viruses is also the mRNA. Here we focus on distinct types of positive strand RNA viruses that differ in the regulatory elements used to promote translation of the viral RNA, as well as in the mechanisms used to evade the series of events connected to antiviral response, including translation shutoff induced in infected cells, assembly of stress granules, and trafficking stress.
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Affiliation(s)
| | | | - Encarnacion Martinez-Salas
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain; (A.E.-B.); (R.F.-V.)
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21
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Huoh YS, Hur S. Death domain fold proteins in immune signaling and transcriptional regulation. FEBS J 2021; 289:4082-4097. [PMID: 33905163 DOI: 10.1111/febs.15901] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/07/2021] [Accepted: 04/23/2021] [Indexed: 01/02/2023]
Abstract
Death domain fold (DDF) superfamily comprises of the death domain (DD), death effector domain (DED), caspase activation recruitment domain (CARD), and pyrin domain (PYD). By utilizing a conserved mode of interaction involving six distinct surfaces, a DDF serves as a building block that can densely pack into homomultimers or filaments. Studies of immune signaling components have revealed that DDF-mediated filament formation plays a central role in mediating signal transduction and amplification. The unique ability of DDFs to self-oligomerize upon external signals and induce oligomerization of partner molecules underlies key processes in many innate immune signaling pathways, as exemplified by RIG-I-like receptor signalosome and inflammasome assembly. Recent studies showed that DDFs are not only limited to immune signaling pathways, but also are involved with transcriptional regulation and other biological processes. Considering that DDF annotation still remains a challenge, the current list of DDFs and their functions may represent just the tip of the iceberg within the full spectrum of DDF biology. In this review, we discuss recent advances in our understanding of DDF functions, structures, and assembly architectures with a focus on CARD- and PYD-containing proteins. We also discuss areas of future research and the potential relationship of DDFs with biomolecular condensates formed by liquid-liquid phase separation (LLPS).
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Affiliation(s)
- Yu-San Huoh
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute at Harvard Medical School, Boston, MA, USA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA, USA
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute at Harvard Medical School, Boston, MA, USA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA, USA
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22
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Porcine Epidemic Diarrhea Virus Infection Induces Caspase-8-Mediated G3BP1 Cleavage and Subverts Stress Granules To Promote Viral Replication. J Virol 2021; 95:JVI.02344-20. [PMID: 33568512 DOI: 10.1128/jvi.02344-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/03/2021] [Indexed: 12/19/2022] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) is an α-coronavirus causing severe diarrhea and high mortality rates in suckling piglets and posing significant economic impact. PEDV replication is completed and results in a large amount of RNA in the cytoplasm. Stress granules (SGs) are dynamic cytosolic RNA granules formed under various stress conditions, including viral infections. Several previous studies suggested that SGs were involved in the antiviral activity of host cells to limit viral propagation. However, the underlying mechanisms are poorly understood. This study aimed to delineate the molecular mechanisms regulating the SG response to PEDV infection. SG formation is induced early during PEDV infection, but as infection proceeds, this ability is lost and SGs disappear at late stages of infection (>18 h postinfection). PEDV infection resulted in the cleavage of Ras-GTPase-activating protein-binding protein 1 (G3BP1) mediated by caspase-8. Using mutational analysis, the PEDV-induced cleavage site within G3BP1 was identified, which differed from the 3C protease cleavage site previously identified. Furthermore, G3BP1 cleavage by caspase-8 at D168 and D169 was confirmed in vitro as well as in vivo The overexpression of cleavage-resistant G3BP1 conferred persistent SG formation and suppression of viral replication. Additionally, the knockdown of endogenous G3BP1 abolished SG formation and potentiated viral replication. Taken together, these data provide new insights into novel strategies in which PEDV limits the host stress response and antiviral responses and indicate that caspase-8-mediated G3BP1 cleavage is important in the failure of host defense against PEDV infection.IMPORTANCE Coronaviruses (CoVs) are drawing extensive attention again since the outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019. CoVs are prone to variation and own the transmission capability by crossing the species barrier resulting in reemergence. How CoVs manipulate the antiviral responses of their hosts needs to be explored. Overall, the study provides new insight into how porcine epidemic diarrhea virus (PEDV) impaired SG assembly by targeting G3BP1 via the host proteinase caspase-8. These findings enhanced the understanding of PEDV infection and might help identify new antiviral targets that could inhibit viral replication and limit the pathogenesis of PEDV.
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23
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Mateju D, Chao JA. Stress granules: regulators or by-products? FEBS J 2021; 289:363-373. [PMID: 33725420 DOI: 10.1111/febs.15821] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/07/2021] [Accepted: 03/12/2021] [Indexed: 12/13/2022]
Abstract
Cells have to deal with conditions that can cause damage to biomolecules and eventually cell death. To protect against these adverse conditions and promote recovery, cells undergo dramatic changes upon exposure to stress. This involves activation of signaling pathways, cell cycle arrest, translational reprogramming, and reorganization of the cytoplasm. Notably, many stress conditions cause a global inhibition of mRNA translation accompanied by the formation of cytoplasmic condensates called stress granules (SGs), which sequester mRNA together with RNA-binding proteins, translation initiation factors, and other components. SGs are highly conserved in eukaryotes, suggesting that they perform an important function during the stress response. Over the years, many different roles have been assigned to SGs, including translational control, mRNA storage, regulation of mRNA decay, antiviral innate immune response, and modulation of signaling pathways. Most of our understanding, however, has been deduced from correlative data based upon the composition of SGs and only recently have technological innovations allowed hypotheses for SG function to be directly tested. Here, we discuss these challenges and explore the evidence related to the function of SGs.
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Affiliation(s)
- Daniel Mateju
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jeffrey A Chao
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
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24
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Onomoto K, Onoguchi K, Yoneyama M. Regulation of RIG-I-like receptor-mediated signaling: interaction between host and viral factors. Cell Mol Immunol 2021; 18:539-555. [PMID: 33462384 PMCID: PMC7812568 DOI: 10.1038/s41423-020-00602-7] [Citation(s) in RCA: 170] [Impact Index Per Article: 56.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/17/2020] [Indexed: 01/31/2023] Open
Abstract
Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are RNA sensor molecules that play essential roles in innate antiviral immunity. Among the three RLRs encoded by the human genome, RIG-I and melanoma differentiation-associated gene 5, which contain N-terminal caspase recruitment domains, are activated upon the detection of viral RNAs in the cytoplasm of virus-infected cells. Activated RLRs induce downstream signaling via their interactions with mitochondrial antiviral signaling proteins and activate the production of type I and III interferons and inflammatory cytokines. Recent studies have shown that RLR-mediated signaling is regulated by interactions with endogenous RNAs and host proteins, such as those involved in stress responses and posttranslational modifications. Since RLR-mediated cytokine production is also involved in the regulation of acquired immunity, the deregulation of RLR-mediated signaling is associated with autoimmune and autoinflammatory disorders. Moreover, RLR-mediated signaling might be involved in the aberrant cytokine production observed in coronavirus disease 2019. Since the discovery of RLRs in 2004, significant progress has been made in understanding the mechanisms underlying the activation and regulation of RLR-mediated signaling pathways. Here, we review the recent advances in the understanding of regulated RNA recognition and signal activation by RLRs, focusing on the interactions between various host and viral factors.
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Affiliation(s)
- Koji Onomoto
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8673, Japan
| | - Kazuhide Onoguchi
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8673, Japan
| | - Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8673, Japan.
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25
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Aoyama-Ishiwatari S, Okazaki T, Iemura SI, Natsume T, Okada Y, Gotoh Y. NUDT21 Links Mitochondrial IPS-1 to RLR-Containing Stress Granules and Activates Host Antiviral Defense. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2021; 206:154-163. [PMID: 33219146 DOI: 10.4049/jimmunol.2000306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 10/23/2020] [Indexed: 11/19/2022]
Abstract
Viral RNA in the cytoplasm of mammalian host cells is recognized by retinoic acid-inducible protein-I-like receptors (RLRs), which localize to cytoplasmic stress granules (SGs). Activated RLRs associate with the mitochondrial adaptor protein IPS-1, which activates antiviral host defense mechanisms, including type I IFN induction. It has remained unclear, however, how RLRs in SGs and IPS-1 in the mitochondrial outer membrane associate physically and engage in information transfer. In this study, we show that NUDT21, an RNA-binding protein that regulates alternative transcript polyadenylation, physically associates with IPS-1 and mediates its localization to SGs in response to transfection with polyinosinic-polycytidylic acid [poly(I:C)], a mimic of viral dsRNA. We found that despite its well-established function in the nucleus, a fraction of NUDT21 localizes to mitochondria in resting cells and becomes localized to SGs in response to poly(I:C) transfection. NUDT21 was also found to be required for efficient type I IFN induction in response to viral infection in both human HeLa cells and mouse macrophage cell line RAW264.7 cells. Our results together indicate that NUDT21 links RLRs in SGs to mitochondrial IPS-1 and thereby activates host defense responses to viral infection.
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Affiliation(s)
| | - Tomohiko Okazaki
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan;
| | - Shun-Ichiro Iemura
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan
| | - Tohru Natsume
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan
| | - Yasushi Okada
- Laboratory for Cell Dynamics Observation, Center for Biosystems Dynamics Research, RIKEN, Osaka 565-0874, Japan
- Department of Physics, Universal Biology Institute, Tokyo 113-0033, Japan; and
- International Research Center for Neurointelligence, World Premier International Research Center Initiative, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yukiko Gotoh
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- International Research Center for Neurointelligence, World Premier International Research Center Initiative, The University of Tokyo, Tokyo 113-0033, Japan
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Zhu H, Zheng C. The Race between Host Antiviral Innate Immunity and the Immune Evasion Strategies of Herpes Simplex Virus 1. Microbiol Mol Biol Rev 2020; 84:e00099-20. [PMID: 32998978 PMCID: PMC7528619 DOI: 10.1128/mmbr.00099-20] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Herpes simplex virus 1 (HSV-1) is very successful in establishing acute and latent infections in humans by counteracting host antiviral innate immune responses. HSV-1 has evolved various strategies to evade host antiviral innate immunity and some cellular survival-associated pathways. Since there is still no vaccine available for HSV-1, a continuous update of information regarding the interaction between HSV-1 infection and the host antiviral innate immunity will provide novel insights to develop new therapeutic strategies for HSV-1 infection and its associated diseases. Here, we update recent studies about how HSV-1 evades the host antiviral innate immunity, specifically how HSV-1 proteins directly or indirectly target the adaptors in the antiviral innate immunity signaling pathways to downregulate the signal transduction. Additionally, some classical intracellular stress responses, which also play important roles in defense of viral invasion, will be discussed here. With a comprehensive review of evasion mechanisms of antiviral innate immunity by HSV-1, we will be able to develop potential new targets for therapies and a possible vaccine against HSV-1 infections.
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Affiliation(s)
- Huifang Zhu
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Neonatal/Pediatric Intensive Care Unit, Children's Medical Center, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Chunfu Zheng
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
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27
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Beauclair G, Streicher F, Chazal M, Bruni D, Lesage S, Gracias S, Bourgeau S, Sinigaglia L, Fujita T, Meurs EF, Tangy F, Jouvenet N. Retinoic Acid Inducible Gene I and Protein Kinase R, but Not Stress Granules, Mediate the Proinflammatory Response to Yellow Fever Virus. J Virol 2020; 94:e00403-20. [PMID: 32878892 PMCID: PMC7592215 DOI: 10.1128/jvi.00403-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/27/2020] [Indexed: 12/21/2022] Open
Abstract
Yellow fever virus (YFV) is an RNA virus primarily targeting the liver. Severe YF cases are responsible for hemorrhagic fever, plausibly precipitated by excessive proinflammatory cytokine response. Pathogen recognition receptors (PRRs), such as the cytoplasmic retinoic acid inducible gene I (RIG-I)-like receptors (RLRs), and the viral RNA sensor protein kinase R (PKR), are known to initiate a proinflammatory response upon recognition of viral genomes. Here, we sought to reveal the main determinants responsible for the acute cytokine expression occurring in human hepatocytes following YFV infection. Using a RIG-I-defective human hepatoma cell line, we found that RIG-I largely contributes to cytokine secretion upon YFV infection. In infected RIG-I-proficient hepatoma cells, RIG-I was localized in stress granules. These granules are large aggregates of stalled translation preinitiation complexes known to concentrate RLRs and PKR and are so far recognized as hubs orchestrating RNA virus sensing. Stable knockdown of PKR in hepatoma cells revealed that PKR contributes to both stress granule formation and cytokine induction upon YFV infection. However, stress granule disruption did not affect the cytokine response to YFV infection, as assessed by small interfering RNA (siRNA)-knockdown-mediated inhibition of stress granule assembly. Finally, no viral RNA was detected in stress granules using a fluorescence in situ hybridization approach coupled with immunofluorescence. Our findings suggest that both RIG-I and PKR mediate proinflammatory cytokine induction in YFV-infected hepatocytes, in a stress granule-independent manner. Therefore, by showing the uncoupling of the cytokine response from the stress granule formation, our model challenges the current view in which stress granules are required for the mounting of the acute antiviral response.IMPORTANCE Yellow fever is a mosquito-borne acute hemorrhagic disease caused by yellow fever virus (YFV). The mechanisms responsible for its pathogenesis remain largely unknown, although increased inflammation has been linked to worsened outcome. YFV targets the liver, where it primarily infects hepatocytes. We found that two RNA-sensing proteins, RIG-I and PKR, participate in the induction of proinflammatory mediators in human hepatocytes infected with YFV. We show that YFV infection promotes the formation of cytoplasmic structures, termed stress granules, in a PKR- but not RIG-I-dependent manner. While stress granules were previously postulated to be essential platforms for immune activation, we found that they are not required for the production of proinflammatory mediators upon YFV infection. Collectively, our work uncovered molecular events triggered by the replication of YFV, which could prove instrumental in clarifying the pathogenesis of the disease, with possible repercussions for disease management.
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Affiliation(s)
| | - Felix Streicher
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Maxime Chazal
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Daniela Bruni
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Sarah Lesage
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
- Université de Paris, Paris, France
| | - Ségolène Gracias
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Salomé Bourgeau
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Laura Sinigaglia
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Takashi Fujita
- Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Eliane F Meurs
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Frédéric Tangy
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
| | - Nolwenn Jouvenet
- Department of Virology, Institut Pasteur, UMR3569 CNRS, Paris, France
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28
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Eiermann N, Haneke K, Sun Z, Stoecklin G, Ruggieri A. Dance with the Devil: Stress Granules and Signaling in Antiviral Responses. Viruses 2020; 12:v12090984. [PMID: 32899736 PMCID: PMC7552005 DOI: 10.3390/v12090984] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 02/07/2023] Open
Abstract
Cells have evolved highly specialized sentinels that detect viral infection and elicit an antiviral response. Among these, the stress-sensing protein kinase R, which is activated by double-stranded RNA, mediates suppression of the host translation machinery as a strategy to limit viral replication. Non-translating mRNAs rapidly condensate by phase separation into cytosolic stress granules, together with numerous RNA-binding proteins and components of signal transduction pathways. Growing evidence suggests that the integrated stress response, and stress granules in particular, contribute to antiviral defense. This review summarizes the current understanding of how stress and innate immune signaling act in concert to mount an effective response against virus infection, with a particular focus on the potential role of stress granules in the coordination of antiviral signaling cascades.
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Affiliation(s)
- Nina Eiermann
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany; (N.E.); (K.H.); (G.S.)
| | - Katharina Haneke
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany; (N.E.); (K.H.); (G.S.)
| | - Zhaozhi Sun
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research (CIID), University of Heidelberg, 69120 Heidelberg, Germany;
| | - Georg Stoecklin
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany; (N.E.); (K.H.); (G.S.)
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research (CIID), University of Heidelberg, 69120 Heidelberg, Germany;
- Correspondence:
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29
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Nevers Q, Albertini AA, Lagaudrière-Gesbert C, Gaudin Y. Negri bodies and other virus membrane-less replication compartments. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118831. [PMID: 32835749 PMCID: PMC7442162 DOI: 10.1016/j.bbamcr.2020.118831] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 12/25/2022]
Abstract
Viruses reshape the organization of the cell interior to achieve different steps of their cellular cycle. Particularly, viral replication and assembly often take place in viral factories where specific viral and cellular proteins as well as nucleic acids concentrate. Viral factories can be either membrane-delimited or devoid of any cellular membranes. In the latter case, they are referred as membrane-less replication compartments. The most emblematic ones are the Negri bodies, which are inclusion bodies that constitute the hallmark of rabies virus infection. Interestingly, Negri bodies and several other viral replication compartments have been shown to arise from a liquid-liquid phase separation process and, thus, constitute a new class of liquid organelles. This is a paradigm shift in the field of virus replication. Here, we review the different aspects of membrane-less virus replication compartments with a focus on the Mononegavirales order and discuss their interactions with the host cell machineries and the cytoskeleton. We particularly examine the interplay between viral factories and the cellular innate immune response, of which several components also form membrane-less condensates in infected cells. Viral factories harbor essential steps of the viral cycle. Some viral factories are devoid of membranes and have liquid organelle properties. Liquid viral factories concentrate cellular factors required for replication. Innate immunity sensors and several ISGs are found in membrane-less condensates. A subtle interplay exists between liquid viral factories and innate immunity actors.
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Affiliation(s)
- Quentin Nevers
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Aurélie A Albertini
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Cécile Lagaudrière-Gesbert
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Yves Gaudin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France.
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30
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Visser LJ, Aloise C, Swatek KN, Medina GN, Olek KM, Rabouw HH, de Groot RJ, Langereis MA, de los Santos T, Komander D, Skern T, van Kuppeveld FJM. Dissecting distinct proteolytic activities of FMDV Lpro implicates cleavage and degradation of RLR signaling proteins, not its deISGylase/DUB activity, in type I interferon suppression. PLoS Pathog 2020; 16:e1008702. [PMID: 32667958 PMCID: PMC7384677 DOI: 10.1371/journal.ppat.1008702] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 07/27/2020] [Accepted: 06/12/2020] [Indexed: 01/12/2023] Open
Abstract
The type I interferon response is an important innate antiviral pathway. Recognition of viral RNA by RIG-I-like receptors (RLRs) activates a signaling cascade that leads to type I interferon (IFN-α/β) gene transcription. Multiple proteins in this signaling pathway (e.g. RIG-I, MDA5, MAVS, TBK1, IRF3) are regulated by (de)ubiquitination events. Most viruses have evolved mechanisms to counter this antiviral response. The leader protease (Lpro) of foot-and-mouth-disease virus (FMDV) has been recognized to reduce IFN-α/β gene transcription; however, the exact mechanism is unknown. The proteolytic activity of Lpro is vital for releasing itself from the viral polyprotein and for cleaving and degrading specific host cell proteins, such as eIF4G and NF-κB. In addition, Lpro has been demonstrated to have deubiquitination/deISGylation activity. Lpro’s deubiquitination/deISGylation activity and the cleavage/degradation of signaling proteins have both been postulated to be important for reduced IFN-α/β gene transcription. Here, we demonstrate that TBK1, the kinase that phosphorylates and activates the transcription factor IRF3, is cleaved by Lpro in FMDV-infected cells as well as in cells infected with a recombinant EMCV expressing Lpro. In vitro cleavage experiments revealed that Lpro cleaves TBK1 at residues 692–694. We also observed cleavage of MAVS in HeLa cells infected with EMCV-Lpro, but only observed decreasing levels of MAVS in FMDV-infected porcine LFPK αVβ6 cells. We set out to dissect Lpro’s ability to cleave RLR signaling proteins from its deubiquitination/deISGylation activity to determine their relative contributions to the reduction of IFN-α/β gene transcription. The introduction of specific mutations, of which several were based on the recently published structure of Lpro in complex with ISG15, allowed us to identify specific amino acid substitutions that separate the different proteolytic activities of Lpro. Characterization of the effects of these mutations revealed that Lpro’s ability to cleave RLR signaling proteins but not its deubiquitination/deISGylation activity correlates with the reduced IFN-β gene transcription. Outbreaks of the picornavirus foot-and-mouth disease virus (FMDV) have significant consequences for animal health and product safety and place a major economic burden on the global livestock industry. Understanding how this notorious animal pathogen suppresses the antiviral type I interferon (IFN-α/β) response may help to develop countermeasures to control FMDV infections. FMDV suppresses the IFN-α/β response through the activity of its Leader protein (Lpro), a protease that can cleave host cell proteins. Lpro was also shown to have deubiquitinase and deISGylase activity, raising the possibility that Lpro suppresses IFN-α/β by removing ubiquitin and/or ISG15, two posttranslational modifications that can regulate the activation, interactions and localization of (signaling) proteins. Here, we show that TBK1 and MAVS, two signaling proteins that are important for activation of IFN-α/β gene transcription, are cleaved by Lpro. By generating Lpro mutants lacking either of these two activities, we demonstrate that Lpro’s ability to cleave signaling proteins, but not its deubiquitination/deISGylase activity, correlates with suppression of IFN-β gene transcription.
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Affiliation(s)
- Linda J. Visser
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | - Chiara Aloise
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | - Kirby N. Swatek
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Gisselle N. Medina
- United States Department of Agriculture, Agricultural Research Service, Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Orient, New York, United States of America
| | - Karin M. Olek
- Department of Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
| | - Huib H. Rabouw
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | - Raoul J. de Groot
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | - Martijn A. Langereis
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | - Teresa de los Santos
- United States Department of Agriculture, Agricultural Research Service, Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Orient, New York, United States of America
| | - David Komander
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
- Ubiquitin Signaling Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Tim Skern
- Department of Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
| | - Frank J. M. van Kuppeveld
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
- * E-mail:
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31
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Dash S, Aydin Y, Wu T. Integrated stress response in hepatitis C promotes Nrf2-related chaperone-mediated autophagy: A novel mechanism for host-microbe survival and HCC development in liver cirrhosis. Semin Cell Dev Biol 2020; 101:20-35. [PMID: 31386899 PMCID: PMC7007355 DOI: 10.1016/j.semcdb.2019.07.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/26/2019] [Accepted: 07/30/2019] [Indexed: 02/06/2023]
Abstract
The molecular mechanism(s) how liver damage during the chronic hepatitis C virus (HCV) infection evolve into cirrhosis and hepatocellular carcinoma (HCC) is unclear. HCV infects hepatocyte, the major cell types in the liver. During infection, large amounts of viral proteins and RNA replication intermediates accumulate in the endoplasmic reticulum (ER) of the infected hepatocyte, which creates a substantial amount of stress response. Infected hepatocyte activates a different type of stress adaptive mechanisms such as unfolded protein response (UPR), antioxidant response (AR), and the integrated stress response (ISR) to promote virus-host cell survival. The hepatic stress is also amplified by another layer of innate and inflammatory response associated with cellular sensing of virus infection through the production of interferon (IFN) and inflammatory cytokines. The interplay between various types of cellular stress signal leads to different forms of cell death such as apoptosis, necrosis, and autophagy depending on the intensity of the stress and nature of the adaptive cellular response. How do the adaptive cellular responses decode such death programs that promote host-microbe survival leading to the establishment of chronic liver disease? In this review, we discuss how the adaptive cellular response through the Nrf2 pathway that promotes virus and cell survival. Furthermore, we provide a glimpse of novel stress-induced Nrf2 mediated compensatory autophagy mechanisms in virus-cell survival that degrade tumor suppressor gene and activation of oncogenic signaling during HCV infection. Based on these facts, we hypothesize that the balance between hepatic stress, inflammation and different types of cell death determines liver disease progression outcomes. We propose that a more nuanced understanding of virus-host interactions under excessive cellular stress may provide an answer to the fundamental questions why some individuals with chronic HCV infection remain at risk of developing cirrhosis, cancer and some do not.
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Affiliation(s)
- Srikanta Dash
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA, 70112, USA.
| | - Yucel Aydin
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA, 70112, USA
| | - Tong Wu
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA, 70112, USA
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32
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Gaete-Argel A, Márquez CL, Barriga GP, Soto-Rifo R, Valiente-Echeverría F. Strategies for Success. Viral Infections and Membraneless Organelles. Front Cell Infect Microbiol 2019; 9:336. [PMID: 31681621 PMCID: PMC6797609 DOI: 10.3389/fcimb.2019.00336] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 09/18/2019] [Indexed: 12/12/2022] Open
Abstract
Regulation of RNA homeostasis or “RNAstasis” is a central step in eukaryotic gene expression. From transcription to decay, cellular messenger RNAs (mRNAs) associate with specific proteins in order to regulate their entire cycle, including mRNA localization, translation and degradation, among others. The best characterized of such RNA-protein complexes, today named membraneless organelles, are Stress Granules (SGs) and Processing Bodies (PBs) which are involved in RNA storage and RNA decay/storage, respectively. Given that SGs and PBs are generally associated with repression of gene expression, viruses have evolved different mechanisms to counteract their assembly or to use them in their favor to successfully replicate within the host environment. In this review we summarize the current knowledge about the viral regulation of SGs and PBs, which could be a potential novel target for the development of broad-spectrum antiviral therapies.
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Affiliation(s)
- Aracelly Gaete-Argel
- Molecular and Cellular Virology Laboratory, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Chantal L Márquez
- Molecular and Cellular Virology Laboratory, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Gonzalo P Barriga
- Emerging Viruses Laboratory, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Ricardo Soto-Rifo
- Molecular and Cellular Virology Laboratory, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Fernando Valiente-Echeverría
- Molecular and Cellular Virology Laboratory, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
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33
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The Leader Protein of Theiler's Virus Prevents the Activation of PKR. J Virol 2019; 93:JVI.01010-19. [PMID: 31292248 DOI: 10.1128/jvi.01010-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
Leader (L) proteins encoded by cardioviruses are multifunctional proteins that contribute to innate immunity evasion. L proteins of Theiler's murine encephalomyelitis virus (TMEV), Saffold virus (SAFV), and encephalomyocarditis virus (EMCV) were reported to inhibit stress granule assembly in infected cells. Here, we show that TMEV L can act at two levels in the stress granule formation pathway: on the one hand, it can inhibit sodium arsenite-induced stress granule assembly without preventing eIF2α phosphorylation and, thus, acts downstream of eIF2α; on the other hand, it can inhibit eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation and the consequent PKR-mediated eIF2α phosphorylation. Interestingly, coimmunostaining experiments revealed that PKR colocalizes with viral double-stranded RNA (dsRNA) in cells infected with L-mutant viruses but not in cells infected with the wild-type virus. Furthermore, PKR coprecipitated with dsRNA from cells infected with L-mutant viruses significantly more than from cells infected with the wild-type virus. These data strongly suggest that L blocks PKR activation by preventing the interaction between PKR and viral dsRNA. In infected cells, L also rendered PKR refractory to subsequent activation by poly(I·C). However, no interaction was observed between L and either dsRNA or PKR. Taken together, our results suggest that, unlike other viral proteins, L indirectly acts on PKR to negatively regulate its responsiveness to dsRNA.IMPORTANCE The leader (L) protein encoded by cardioviruses is a very short multifunctional protein that contributes to evasion of the host innate immune response. This protein notably prevents the formation of stress granules in infected cells. Using Theiler's virus as a model, we show that L proteins can act at two levels in the stress response pathway leading to stress granule formation, the most striking one being the inhibition of eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation. Interestingly, the leader protein appears to inhibit PKR via a novel mechanism by rendering this kinase unable to detect double-stranded RNA, its typical activator. Unlike other viral proteins, such as influenza virus NS1, the leader protein appears to interact with neither PKR nor double-stranded RNA, suggesting that it acts indirectly to trigger the inhibition of the kinase.
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34
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Sun D, Wen X, Wang M, Mao S, Cheng A, Yang X, Jia R, Chen S, Yang Q, Wu Y, Zhu D, Liu M, Zhao X, Zhang S, Wang Y, Xu Z, Chen Z, Zhu L, Luo Q, Liu Y, Yu Y, Zhang L, Chen X. Apoptosis and Autophagy in Picornavirus Infection. Front Microbiol 2019; 10:2032. [PMID: 31551969 PMCID: PMC6733961 DOI: 10.3389/fmicb.2019.02032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/19/2019] [Indexed: 12/13/2022] Open
Abstract
Cell death is a fundamental process in maintaining cellular homeostasis, which can be either accidental or programed. Programed cell death depends on the specific signaling pathways, resulting in either lytic or non-lytic morphology. It exists in two primary forms: apoptosis and autophagic cell death. Apoptosis is a non-lytic and selective cell death program, which is executed by caspases in response to non-self or external stimuli. In contrast, autophagy is crucial for maintaining cellular homeostasis via the degradation and recycling of cellular components. These two mechanisms also function in the defense against pathogen attack. However, picornaviruses have evolved to utilize diverse strategies and target critical components to regulate the apoptotic and autophagic processes for optimal replication and the release from the host cell. Although an increasing number of investigations have shown that the apoptosis and autophagy are altered in picornavirus infection, the mechanism by which viruses take advantage of these two processes remains unknown. In this review, we discuss the mechanisms of picornavirus executes cellular apoptosis and autophagy at the molecular level and the relationship between these interactions and viral pathogenesis.
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Affiliation(s)
- Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xingjian Wen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaoyao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Dekang Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yin Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhiwen Xu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhengli Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qihui Luo
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yunya Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yanling Yu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaoyue Chen
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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Law LMJ, Razooky BS, Li MMH, You S, Jurado A, Rice CM, MacDonald MR. ZAP's stress granule localization is correlated with its antiviral activity and induced by virus replication. PLoS Pathog 2019; 15:e1007798. [PMID: 31116799 PMCID: PMC6548403 DOI: 10.1371/journal.ppat.1007798] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 06/04/2019] [Accepted: 04/29/2019] [Indexed: 11/24/2022] Open
Abstract
Cellular antiviral programs encode molecules capable of targeting multiple steps in the virus lifecycle. Zinc-finger antiviral protein (ZAP) is a central and general regulator of antiviral activity that targets pathogen mRNA stability and translation. ZAP is diffusely cytoplasmic, but upon infection ZAP is targeted to particular cytoplasmic structures, termed stress granules (SGs). However, it remains unclear if ZAP’s antiviral activity correlates with SG localization, and what molecular cues are required to induce this localization event. Here, we use Sindbis virus (SINV) as a model infection and find that ZAP’s localization to SGs can be transient. Sometimes no apparent viral infection follows ZAP SG localization but ZAP SG localization always precedes accumulation of SINV non-structural protein, suggesting virus replication processes trigger SG formation and ZAP recruitment. Data from single-molecule RNA FISH corroborates this finding as the majority of cells with ZAP localization in SGs contain low levels of viral RNA. Furthermore, ZAP recruitment to SGs occurred in ZAP-expressing cells when co-cultured with cells replicating full-length SINV, but not when co-cultured with cells replicating a SINV replicon. ZAP recruitment to SGs is functionally important as a panel of alanine ZAP mutants indicate that the anti-SINV activity is correlated with ZAP’s ability to localize to SGs. As ZAP is a central component of the cellular antiviral programs, these data provide further evidence that SGs are an important cytoplasmic antiviral hub. These findings provide insight into how antiviral components are regulated upon virus infection to inhibit virus spread. Organisms encode immune programs, present in most somatic cells, to combat pathogens. The components of these antiviral programs are both constitutively expressed and highly upregulated upon pathogen recognition. Interestingly, a broadly acting antiviral factor is the zinc-finger antiviral protein (ZAP). ZAP is a primarily cytoplasmic protein that upon various cellular stresses, such as virus infection, can localize to specific cytoplasmic complexes termed stress granules (SGs). SGs are hubs that regulate mRNA stability and translation. Here, we show that SG localization is (i) correlated with ZAP’s antiviral function, (ii) most likely triggered during the early stages of virus replication, and (iii) a highly dynamic and transient process. Collectively, our data highlight the genetic and dynamic components of ZAP-mediated antiviral activity.
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Affiliation(s)
- Lok Man John Law
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
| | - Brandon S. Razooky
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
| | - Melody M. H. Li
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
| | - Shihyun You
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
| | - Andrea Jurado
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
| | - Charles M. Rice
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
| | - Margaret R. MacDonald
- The Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, United States of America
- * E-mail:
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Essential Role of Enterovirus 2A Protease in Counteracting Stress Granule Formation and the Induction of Type I Interferon. J Virol 2019; 93:JVI.00222-19. [PMID: 30867299 DOI: 10.1128/jvi.00222-19] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 03/04/2019] [Indexed: 12/20/2022] Open
Abstract
Most viruses have acquired mechanisms to suppress antiviral alpha/beta interferon (IFN-α/β) and stress responses. Enteroviruses (EVs) actively counteract the induction of IFN-α/β gene transcription and stress granule (SG) formation, which are increasingly implicated as a platform for antiviral signaling, but the underlying mechanisms remain poorly understood. Both viral proteases (2Apro and 3Cpro) have been implicated in the suppression of these responses, but these conclusions predominantly rely on ectopic overexpression of viral proteases or addition of purified viral proteases to cell lysates. Here, we present a detailed and comprehensive comparison of the effect of individual enterovirus proteases on the formation of SGs and the induction of IFN-α/β gene expression in infected cells for representative members of the enterovirus species EV-A to EV-D. First, we show that SG formation and IFN-β induction are suppressed in cells infected with EV-A71, coxsackie B3 virus (CV-B3), CV-A21, and EV-D68. By introducing genes encoding CV-B3 proteases in a recombinant encephalomyocarditis virus (EMCV) that was designed to efficiently activate antiviral responses, we show that CV-B3 2Apro, but not 3Cpro, is the major antagonist that counters SG formation and IFN-β gene transcription and that 2Apro's proteolytic activity is essential for both functions. 2Apro efficiently suppressed SG formation despite protein kinase R (PKR) activation and α subunit of eukaryotic translation initiation factor 2 phosphorylation, suggesting that 2Apro antagonizes SG assembly or promotes its disassembly. Finally, we show that the ability to suppress SG formation and IFN-β gene transcription is conserved in the 2Apro of EV-A71, CV-A21, and EV-D68. Collectively, our results indicate that enterovirus 2Apro plays a key role in inhibiting innate antiviral cellular responses.IMPORTANCE Enteroviruses are important pathogens that can cause a variety of diseases in humans, including aseptic meningitis, myocarditis, hand-foot-and-mouth disease, conjunctivitis, and acute flaccid paralysis. Like many other viruses, enteroviruses must counteract antiviral cellular responses to establish an infection. It has been suggested that enterovirus proteases cleave cellular factors to perturb antiviral pathways, but the exact contribution of viral proteases 2Apro and 3Cpro remains elusive. Here, we show that 2Apro, but not 3Cpro, of all four human EV species (EV-A to EV-D) inhibits SG formation and IFN-β gene transcription. Our observations suggest that enterovirus 2Apro has a conserved function in counteracting antiviral host responses and thereby is the main enterovirus "security protein." Understanding the molecular mechanisms of enterovirus immune evasion strategies may help to develop countermeasures to control infections with these viruses.
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Small molecule ISRIB suppresses the integrated stress response within a defined window of activation. Proc Natl Acad Sci U S A 2019; 116:2097-2102. [PMID: 30674674 PMCID: PMC6369741 DOI: 10.1073/pnas.1815767116] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The integrated stress response (ISR) protects cells from a variety of harmful stressors by temporarily halting protein synthesis. However, chronic ISR activation has pathological consequences and is linked to several neurological disorders. Pharmacological inhibition of chronic ISR activity emerges as a powerful strategy to treat ISR-mediated neurodegeneration but is typically linked to adverse effects due to the ISR’s importance for normal cellular function. Paradoxically, the small-molecule ISR inhibitor ISRIB has promising therapeutic potential in vivo without overt side effects. We demonstrate here that ISRIB inhibits low-level ISR activity, but does not affect strong ISR signaling. We thereby provide a plausible mechanism of how ISRIB counteracts toxic chronic ISR activity, without disturbing the cytoprotective effects of a strong acute ISR. Activation of the integrated stress response (ISR) by a variety of stresses triggers phosphorylation of the α-subunit of translation initiation factor eIF2. P-eIF2α inhibits eIF2B, the guanine nucleotide exchange factor that recycles inactive eIF2•GDP to active eIF2•GTP. eIF2 phosphorylation thereby represses translation. Persistent activation of the ISR has been linked to the development of several neurological disorders, and modulation of the ISR promises new therapeutic strategies. Recently, a small-molecule ISR inhibitor (ISRIB) was identified that rescues translation in the presence of P-eIF2α by facilitating the assembly of more active eIF2B. ISRIB enhances cognitive memory processes and has therapeutic effects in brain-injured mice without displaying overt side effects. While using ISRIB to investigate the ISR in picornavirus-infected cells, we observed that ISRIB rescued translation early in infection when P-eIF2α levels were low, but not late in infection when P-eIF2α levels were high. By treating cells with varying concentrations of poly(I:C) or arsenite to induce the ISR, we provide additional proof that ISRIB is unable to inhibit the ISR when intracellular P-eIF2α concentrations exceed a critical threshold level. Together, our data demonstrate that the effects of pharmacological activation of eIF2B are tuned by P-eIF2α concentration. Thus, ISRIB can mitigate undesirable outcomes of low-level ISR activation that may manifest neurological disease but leaves the cytoprotective effects of acute ISR activation intact. The insensitivity of cells to ISRIB during acute ISR may explain why ISRIB does not cause overt toxic side effects in vivo.
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38
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Abstract
Detection of double-stranded RNAs (dsRNAs) is a central mechanism of innate immune defense in many organisms. We here discuss several families of dsRNA-binding proteins involved in mammalian antiviral innate immunity. These include RIG-I-like receptors, protein kinase R, oligoadenylate synthases, adenosine deaminases acting on RNA, RNA interference systems, and other proteins containing dsRNA-binding domains and helicase domains. Studies suggest that their functions are highly interdependent and that their interdependence could offer keys to understanding the complex regulatory mechanisms for cellular dsRNA homeostasis and antiviral immunity. This review aims to highlight their interconnectivity, as well as their commonalities and differences in their dsRNA recognition mechanisms.
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Affiliation(s)
- Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA; .,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA
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39
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Foot-and-Mouth Disease Virus Leader Protease Cleaves G3BP1 and G3BP2 and Inhibits Stress Granule Formation. J Virol 2019; 93:JVI.00922-18. [PMID: 30404792 DOI: 10.1128/jvi.00922-18] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 10/26/2018] [Indexed: 12/31/2022] Open
Abstract
Like other viruses, the picornavirus foot-and-mouth disease virus (FMDV; genus Aphthovirus), one of the most notorious pathogens in the global livestock industry, needs to navigate antiviral host responses to establish an infection. There is substantial insight into how FMDV suppresses the type I interferon (IFN) response, but it is largely unknown whether and how FMDV modulates the integrated stress response. Here, we show that the stress response is suppressed during FMDV infection. Using a chimeric recombinant encephalomyocarditis virus (EMCV), in which we functionally replaced the endogenous stress response antagonist by FMDV leader protease (Lpro) or 3Cpro, we demonstrate an essential role for Lpro in suppressing stress granule (SG) formation. Consistently, infection with a recombinant FMDV lacking Lpro resulted in SG formation. Additionally, we show that Lpro cleaves the known SG scaffold proteins G3BP1 and G3BP2 but not TIA-1. We demonstrate that the closely related equine rhinitis A virus (ERAV) Lpro also cleaves G3BP1 and G3BP2 and also suppresses SG formation, indicating that these abilities are conserved among aphthoviruses. Neither FMDV nor ERAV Lpro interfered with phosphorylation of RNA-dependent protein kinase (PKR) or eIF2α, indicating that Lpro does not affect SG formation by inhibiting the PKR-triggered signaling cascade. Taken together, our data suggest that aphthoviruses actively target scaffolding proteins G3BP1 and G3BP2 and antagonize SG formation to modulate the integrated stress response.IMPORTANCE The picornavirus foot-and-mouth disease virus (FMDV) is a notorious animal pathogen that puts a major economic burden on the global livestock industry. Outbreaks have significant consequences for animal health and product safety. Like many other viruses, FMDV must manipulate antiviral host responses to establish infection. Upon infection, viral double-stranded RNA (dsRNA) is detected, which results in the activation of the RNA-dependent protein kinase (PKR)-mediated stress response, leading to a stop in cellular and viral translation and the formation of stress granules (SG), which are thought to have antiviral properties. Here, we show that FMDV can suppress SG formation via its leader protease (Lpro). Simultaneously, we observed that Lpro can cleave the SG scaffolding proteins G3BP1 and G3BP2. Understanding the molecular mechanisms of the antiviral host response evasion strategies of FMDV may help to develop countermeasures to control FMDV infections in the future.
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40
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SG formation relies on eIF4GI-G3BP interaction which is targeted by picornavirus stress antagonists. Cell Discov 2019; 5:1. [PMID: 30603102 PMCID: PMC6312541 DOI: 10.1038/s41421-018-0068-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/07/2018] [Accepted: 10/11/2018] [Indexed: 01/16/2023] Open
Abstract
Typical stress granules (tSGs) are stalled translation pre-initiation complex aggregations in the cytoplasm, and their formation is a common consequence of translation initiation inhibition under stress. We previously found that 2A protease of picornaviruses blocks tSG formation and induces atypical SG formation, but the molecular mechanism by which 2A inhibits tSG formation remains unclear. Here, we found that eukaryotic translation initiation factor 4 gamma1 (eIF4GI) is critical for tSG formation by interacting with Ras-GTPase-activating protein SH3-domain-binding protein (G3BP), and this interaction is mediated by aa 182-203 of eIF4GI and the RNA-binding domain of G3BP. Upon eIF4GI-G3BP interaction, eIF4GI can assemble into tSGs and rescue tSG formation. Finally, we found that 2A or L protein of picornaviruses blocks tSG formation by disrupting eIF4GI-G3BP interaction. Our findings provide the first evidence that eIF4GI-G3BP interaction is indispensable for tSG formation, and 2A or L protein of picornaviruses interferes eIF4GI-G3BP interaction, thereby blocking tSG formation.
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41
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Intracellular RNA Sensing in Mammalian Cells: Role in Stress Response and Cancer Therapies. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2019; 344:31-89. [DOI: 10.1016/bs.ircmb.2018.08.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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42
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Medina GN, Segundo FDS, Stenfeldt C, Arzt J, de Los Santos T. The Different Tactics of Foot-and-Mouth Disease Virus to Evade Innate Immunity. Front Microbiol 2018; 9:2644. [PMID: 30483224 PMCID: PMC6241212 DOI: 10.3389/fmicb.2018.02644] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/17/2018] [Indexed: 12/18/2022] Open
Abstract
Like all pathogens, foot-and-mouth disease virus (FMDV) is recognized by the immune system inducing a heightened immune response mainly mediated by type I and type III IFNs. To overcome the strong antiviral response induced by these cytokines, FMDV has evolved many strategies exploiting each region of its small RNA genome. These include: (a) inhibition of IFN induction at the transcriptional and translational level, (b) inhibition of protein trafficking; (c) blockage of specific post-translational modifications in proteins that regulate innate immune signaling; (d) modulation of autophagy; (e) inhibition of stress granule formation; and (f) in vivo modulation of immune cell function. Here, we summarize and discuss FMDV virulence factors and the host immune footprint that characterize infection in cell culture and in the natural hosts.
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Affiliation(s)
- Gisselle N Medina
- Plum Island Animal Disease Center, United States Department of Agriculture, Agricultural Research Service, Orient, NY, United States.,Codagenix Inc., Farmingdale, NY, United States
| | - Fayna Díaz-San Segundo
- Plum Island Animal Disease Center, United States Department of Agriculture, Agricultural Research Service, Orient, NY, United States.,Animal and Plant Health Inspection Service, Plum Island Animal Disease Center, United States Department of Agriculture, Orient, NY, United States
| | - Carolina Stenfeldt
- Plum Island Animal Disease Center, United States Department of Agriculture, Agricultural Research Service, Orient, NY, United States.,Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, United States
| | - Jonathan Arzt
- Plum Island Animal Disease Center, United States Department of Agriculture, Agricultural Research Service, Orient, NY, United States
| | - Teresa de Los Santos
- Plum Island Animal Disease Center, United States Department of Agriculture, Agricultural Research Service, Orient, NY, United States
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43
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Freundt EC, Drappier M, Michiels T. Innate Immune Detection of Cardioviruses and Viral Disruption of Interferon Signaling. Front Microbiol 2018; 9:2448. [PMID: 30369921 PMCID: PMC6194174 DOI: 10.3389/fmicb.2018.02448] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/25/2018] [Indexed: 12/24/2022] Open
Abstract
Cardioviruses are members of the Picornaviridae family and infect a variety of mammals, from mice to humans. Replication of cardioviruses produces double stranded RNA that is detected by helicases in the RIG-I-like receptor family and leads to a signaling cascade to produce type I interferon. Like other viruses within Picornaviridae, however, cardioviruses have evolved several mechanisms to inhibit interferon production. In this review, we summarize recent findings that have uncovered several proteins enabling efficient detection of cardiovirus dsRNA and discuss which cell types may be most important for interferon production in vivo. Additionally, we describe how cardiovirus proteins L, 3C and L∗ disrupt interferon production and antagonize the antiviral activity of interferon effector molecules.
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Affiliation(s)
- Eric C Freundt
- Department of Biology, The University of Tampa, Tampa, FL, United States
| | - Melissa Drappier
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Thomas Michiels
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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44
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Inhibition of Stress Granule Formation by Middle East Respiratory Syndrome Coronavirus 4a Accessory Protein Facilitates Viral Translation, Leading to Efficient Virus Replication. J Virol 2018; 92:JVI.00902-18. [PMID: 30068649 DOI: 10.1128/jvi.00902-18] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/26/2018] [Indexed: 12/13/2022] Open
Abstract
Stress granule (SG) formation is generally triggered as a result of stress-induced translation arrest. The impact of SG formation on virus replication varies among different viruses, and the significance of SGs in coronavirus (CoV) replication is largely unknown. The present study examined the biological role of SGs in Middle East respiratory syndrome (MERS)-CoV replication. The MERS-CoV 4a accessory protein is known to inhibit SG formation in cells in which it was expressed by binding to double-stranded RNAs and inhibiting protein kinase R (PKR)-mediated phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α). Replication of MERS-CoV lacking the genes for 4a and 4b (MERS-CoV-Δp4), but not MERS-CoV, induced SG accumulation in MERS-CoV-susceptible HeLa/CD26 cells, while replication of both viruses failed to induce SGs in Vero cells, demonstrating cell type-specific differences in MERS-CoV-Δp4-induced SG formation. MERS-CoV-Δp4 replicated less efficiently than MERS-CoV in HeLa/CD26 cells, and inhibition of SG formation by small interfering RNA-mediated depletion of the SG components promoted MERS-CoV-Δp4 replication, demonstrating that SG formation was detrimental for MERS-CoV replication. Inefficient MERS-CoV-Δp4 replication was not due to either the induction of type I and type III interferons or the accumulation of viral mRNAs in the SGs. Rather, it was due to the inefficient translation of viral proteins, which was caused by high levels of PKR-mediated eIF2α phosphorylation and likely by the confinement of various factors that are required for translation in the SGs. Finally, we established that deletion of the 4a gene alone was sufficient for inducing SGs in infected cells. Our study revealed that 4a-mediated inhibition of SG formation facilitates viral translation, leading to efficient MERS-CoV replication.IMPORTANCE Middle East respiratory syndrome coronavirus (MERS-CoV) causes respiratory failure with a high case fatality rate in patients, yet effective antivirals and vaccines are currently not available. Stress granule (SG) formation is one of the cellular stress responses to virus infection and is generally triggered as a result of stress-induced translation arrest. SGs can be beneficial or detrimental for virus replication, and the biological role of SGs in CoV infection is unclear. The present study showed that the MERS-CoV 4a accessory protein, which was reported to block SG formation in cells in which it was expressed, inhibited SG formation in infected cells. Our data suggest that 4a-mediated inhibition of SG formation facilitates the translation of viral mRNAs, resulting in efficient virus replication. To our knowledge, this report is the first to show the biological significance of SG in CoV replication and provides insight into the interplay between MERS-CoV and antiviral stress responses.
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45
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Defining the Role of Stress Granules in Innate Immune Suppression by the Herpes Simplex Virus 1 Endoribonuclease VHS. J Virol 2018; 92:JVI.00829-18. [PMID: 29793959 DOI: 10.1128/jvi.00829-18] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 05/16/2018] [Indexed: 12/20/2022] Open
Abstract
In response to virus-induced shutoff host protein synthesis, dynamic aggregates containing mRNA, RNA-binding proteins and translation factors termed stress granules (SGs) often accumulate within the cytoplasm. SGs typically form following phosphorylation and inactivation of the eukaryotic translation initiation factor 2α (eIF2α), a substrate of the double-stranded RNA (dsRNA)-activated kinase protein kinase R (PKR). The detection of innate immune sensors and effectors like PKR at SGs suggests a role in pathogen nucleic acid sensing. However, the functional importance of SGs in host innate responses is unclear and has primarily been examined in response to infection with select RNA viruses. During infection with the DNA virus herpes simplex virus 1 (HSV-1), the virus-encoded virion host shutoff (VHS) endoribonuclease is required to restrict interferon production, PKR activation, and SG formation, although the relationship between these activities remains incompletely understood. Here, we show that in cells infected with a VHS-deficient HSV-1 (ΔVHS) dsRNA accumulated and localized to SGs. Surprisingly, formation of dsRNA and its concentration at SGs was not required for beta interferon mRNA induction, indicating that suppression of type I interferon induction by VHS does not stem from its control of dsRNA accumulation. Instead, STING signaling downstream of cGMP-AMP synthase (cGAS)-dependent DNA sensing is required for beta interferon induction. In contrast, significantly less PKR activation is observed when SG assembly is disrupted by ISRIB, an inhibitor of phosphorylated eIF2α-mediated translation repression, or depleting SG scaffolding proteins G3BP1 or TIA1. This demonstrates that PKR activation is intimately linked to SG formation and that SGs form important hubs to potentiate PKR activation during infection.IMPORTANCE Formation of cytoplasmic stress granules that are enriched for innate immune sensors and effectors is suppressed during many viral infections. It is unclear, however, to what extent this is a side effect of viral efforts to maintain protein synthesis or intentional disruption of a hub for innate immune sensing. In this study, we utilize a herpes simplex virus 1 mutant lacking the RNA nuclease VHS which upon infection induces SGs, PKR activation, and beta interferon to address this question. We show that dsRNA is localized to SGs and that SGs can function to promote PKR activation in the context of a DNA virus infection, but we find no evidence to support their importance for interferon induction during HSV-1 infection.
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46
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Kang JS, Hwang YS, Kim LK, Lee S, Lee WB, Kim-Ha J, Kim YJ. OASL1 Traps Viral RNAs in Stress Granules to Promote Antiviral Responses. Mol Cells 2018; 41:214-223. [PMID: 29463066 PMCID: PMC5881095 DOI: 10.14348/molcells.2018.2293] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/11/2017] [Accepted: 12/17/2017] [Indexed: 12/24/2022] Open
Abstract
Oligoadenylate synthetase (OAS) protein family is the major interferon (IFN)-stimulated genes responsible for the activation of RNase L pathway upon viral infection. OAS-like (OASL) is also required for inhibition of viral growth in human cells, but the loss of one of its mouse homolog, OASL1, causes a severe defect in termination of type I interferon production. To further investigate the antiviral activity of OASL1, we examined its subcellular localization and regulatory roles in IFN production in the early and late stages of viral infection. We found OASL1, but not OASL2, formed stress granules trapping viral RNAs and promoted efficient RLR signaling in early stages of infection. Stress granule formation was dependent on RNA binding activity of OASL1. But in the late stages of infection, OASL1 interacted with IRF7 transcripts to inhibit translation resulting in down regulation of IFN production. These results implicate that OASL1 plays context dependent functions in the antiviral response for the clearance and resolution of viral infections.
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Affiliation(s)
- Ji-Seon Kang
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722,
Korea
- Severance Biomedical Science Institute and BK21 PLUS project to Medical Sciences, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 06230,
Korea
| | - Yune-Sahng Hwang
- Department for Integrated OMICs for Biomedical Science, Yonsei University, Seoul 03722,
Korea
| | - Lark Kyun Kim
- Severance Biomedical Science Institute and BK21 PLUS project to Medical Sciences, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 06230,
Korea
| | - Sujung Lee
- Department of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 05006,
Korea
| | - Wook-Bin Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722,
Korea
- Korea Institute of Science and Technology (KIST) Gangneung Institute of Natural Products, Gangneung 25451,
Korea
| | - Jeongsil Kim-Ha
- Department of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 05006,
Korea
| | - Young-Joon Kim
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722,
Korea
- Department for Integrated OMICs for Biomedical Science, Yonsei University, Seoul 03722,
Korea
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Hu Z, Wang Y, Tang Q, Yang X, Qin Y, Chen M. Inclusion bodies of human parainfluenza virus type 3 inhibit antiviral stress granule formation by shielding viral RNAs. PLoS Pathog 2018. [PMID: 29518158 PMCID: PMC5860793 DOI: 10.1371/journal.ppat.1006948] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Viral invasion triggers the activation of the host antiviral response. Besides the innate immune response, stress granules (SGs) also act as an additional defense response to combat viral replication. However, many viruses have evolved various strategies to suppress SG formation to facilitate their own replication. Here, we show that viral mRNAs derived from human parainfluenza virus type 3 (HPIV3) infection induce SG formation in an eIF2α phosphorylation- and PKR-dependent manner in which viral mRNAs are sequestered and viral replication is inhibited independent of the interferon signaling pathway. Furthermore, we found that inclusion body (IB) formation by the interaction of the nucleoprotein (N) and phosphoprotein (P) of HPIV3 correlated with SG suppression. In addition, co-expression of P with NL478A (a point mutant of N, which is unable to form IBs with P) or with NΔN10 (lacking N-terminal 10 amino acids of N, which could form IBs with P but was unable to synthesize or shield viral RNAs) failed to inhibit SG formation, suggesting that inhibition of SG formation also correlates with the capacity of IBs to synthesize and shield viral RNAs. Therefore, we provide a model whereby viral IBs escape the antiviral effect of SGs by concealing their own newly synthesized viral RNAs and offer new insights into the emerging role of IBs in viral replication. Human parainfluenza virus type 3 (HPIV3) is one of the major causes of acute respiratory tract diseases such as pneumonia and bronchitis in infants and children. Virus invasion activates cellular stress responses. One of these responses is the formation of SGs which counteract viral replication. However, many viruses have evolved various strategies to suppress SG formation, thus facilitating their own replication. We sought to determine if (and how) HPIV3 modulates SG formation to facilitate its replication and found that the viral messenger RNAs (mRNAs) of HPIV3 trigger SG formation in infected cells. As time increased post-infection, the number of cells containing SGs increased as well. To escape this response, HPIV3 forms IBs that shield viral RNAs, thereby preventing SG formation and allowing the virus to replicate and survive—and potentially invade other cells.
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Affiliation(s)
- Zhulong Hu
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, LuoJia Hill, Wuhan, China
| | - Yuang Wang
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, LuoJia Hill, Wuhan, China
| | - Qiaopeng Tang
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, LuoJia Hill, Wuhan, China
| | - Xiaodan Yang
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, LuoJia Hill, Wuhan, China
| | - Yali Qin
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, LuoJia Hill, Wuhan, China
| | - Mingzhou Chen
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, LuoJia Hill, Wuhan, China
- * E-mail:
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48
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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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49
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Scutigliani EM, Kikkert M. Interaction of the innate immune system with positive-strand RNA virus replication organelles. Cytokine Growth Factor Rev 2017; 37:17-27. [PMID: 28709747 PMCID: PMC7108334 DOI: 10.1016/j.cytogfr.2017.05.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 05/15/2017] [Indexed: 02/08/2023]
Abstract
All +RNA viruses induce replication organelles to shield viral RNA from innate immune surveillance. Recent literature suggests that non-self or aberrant-self membrane structures can be tagged with LC3 or ubiquitin. Interferon-induced GTPases then recognize these tags and destroy the membrane structures, thereby exposing PAMPs. More research will have to indicate whether this is a general antiviral mechanism affecting +RNA virus infections.
The potential health risks associated with (re-)emerging positive-strand RNA (+RNA) viruses emphasizes the need for understanding host-pathogen interactions for these viruses. The innate immune system forms the first line of defense against pathogenic organisms like these and is responsible for detecting pathogen-associated molecular patterns (PAMPs). Viral RNA is a potent inducer of antiviral innate immune signaling, provoking an antiviral state by directing expression of interferons (IFNs) and pro-inflammatory cytokines. However, +RNA viruses developed various methods to avoid detection and downstream signaling, including isolation of viral RNA replication in membranous viral replication organelles (ROs). These structures therefore play a central role in infection, and consequently, loss of RO integrity might simultaneously result in impaired viral replication and enhanced antiviral signaling. This review summarizes the first indications that the innate immune system indeed has tools to disrupt viral ROs and other non- or aberrant-self membrane structures, and may do this by marking these membranes with proteins such as microtubule-associated protein 1A/1B-light chain 3 (LC3) and ubiquitin, resulting in the recruitment of IFN-inducible GTPases. Further studies should evaluate whether this process forms a general effector mechanism in +RNA virus infection, thereby creating the opportunity for development of novel antiviral therapies.
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Affiliation(s)
- Enzo Maxim Scutigliani
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marjolein Kikkert
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.
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50
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Abstract
Efficient viral gene expression is threatened by cellular stress response programmes that rapidly reprioritize the translation machinery in response to varied environmental assaults, including virus infection. This results in inhibition of bulk synthesis of housekeeping proteins and causes the aggregation of messenger ribonucleoprotein complexes into cytoplasmic foci that are known as stress granules, which can entrap viral mRNAs. There is accumulating evidence for the antiviral nature of stress granules, which is supported by the discovery of many viral factors that interfere with stress granule formation and/or function. This Review focuses on recent advances in our understanding of the role of translation inhibition and stress granules in antiviral immune responses.
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