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Huang W, Kew C, Fernandes SDA, Löhrke A, Han L, Demetriades C, Antebi A. Decreased spliceosome fidelity and egl-8 intron retention inhibit mTORC1 signaling to promote longevity. Nat Aging 2022; 2:796-808. [PMID: 37118503 PMCID: PMC10154236 DOI: 10.1038/s43587-022-00275-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 07/28/2022] [Indexed: 11/09/2022]
Abstract
AbstractChanges in splicing fidelity are associated with loss of homeostasis and aging, yet only a handful of splicing factors have been shown to be causally required to promote longevity, and the underlying mechanisms and downstream targets in these paradigms remain elusive. Surprisingly, we found a hypomorphic mutation within ribonucleoprotein RNP-6/poly(U)-binding factor 60 kDa (PUF60), a spliceosome component promoting weak 3′-splice site recognition, which causes aberrant splicing, elevates stress responses and enhances longevity in Caenorhabditis elegans. Through genetic suppressor screens, we identify a gain-of-function mutation within rbm-39, an RNP-6-interacting splicing factor, which increases nuclear speckle formation, alleviates splicing defects and curtails longevity caused by rnp-6 mutation. By leveraging the splicing changes induced by RNP-6/RBM-39 activities, we uncover intron retention in egl-8/phospholipase C β4 (PLCB4) as a key splicing target prolonging life. Genetic and biochemical evidence show that neuronal RNP-6/EGL-8 downregulates mammalian target of rapamycin complex 1 (mTORC1) signaling to control organismal lifespan. In mammalian cells, PUF60 downregulation also potently and specifically inhibits mTORC1 signaling. Altogether, our results reveal that splicing fidelity modulates lifespan through mTOR signaling.
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2
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Tiku V, Kew C, Kofoed EM, Peng Y, Dikic I, Tan MW. Acinetobacter baumannii Secretes a Bioactive Lipid That Triggers Inflammatory Signaling and Cell Death. Front Microbiol 2022; 13:870101. [PMID: 35615509 PMCID: PMC9125205 DOI: 10.3389/fmicb.2022.870101] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 03/28/2022] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is a highly pathogenic Gram-negative bacterium that causes severe infections with very high fatality rates. A. baumannii infection triggers innate as well as adaptive immunity, however, our understanding of the inflammatory factors secreted by A. baumannii that alarm the immune system remains limited. In this study, we report that the lab adapted and clinical strains of A. baumannii secrete an inflammatory bioactive factor which activates TLR2, leading to canonical IRAK4-dependent NF-κB signaling and production of pro-inflammatory cytokines interleukin (IL)-6 and IL-8 and activation of the inflammasome pathway causing pyroptotic cell death. Biochemical fractionation of the A. baumannii culture filtrate revealed the hydrophobic nature of the inflammatory factor. Concordantly, lipase treatment of the culture filtrate or TLR2 inhibition in macrophages abrogated NF-κB activation and cell death induction. Culture filtrates from the LPS- and lipoprotein-deficient A. baumannii mutants retain immuno-stimulatory properties suggesting that a lipid other than these known stimulatory molecules can trigger inflammation during A. baumannii infection. Our results reveal that A. baumannii secretes a previously unappreciated inflammatory bioactive lipid that activates multiple pro-inflammatory signaling pathways and induces cell death in human and murine macrophages.
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Affiliation(s)
- Varnesh Tiku
- Department of Infectious Diseases, Genentech, South San Francisco, CA, United States
- *Correspondence: Varnesh Tiku,
| | - Chun Kew
- Faculty of Medicine, Institute of Biochemistry II, Goethe University Frankfurt, Frankfurt, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Eric M. Kofoed
- Department of Infectious Diseases, Genentech, South San Francisco, CA, United States
| | - Yutian Peng
- Department of Infectious Diseases, Genentech, South San Francisco, CA, United States
| | - Ivan Dikic
- Faculty of Medicine, Institute of Biochemistry II, Goethe University Frankfurt, Frankfurt, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Max Planck Institute of Biophysics, Frankfurt, Germany
- Ivan Dikic,
| | - Man-Wah Tan
- Department of Infectious Diseases, Genentech, South San Francisco, CA, United States
- Man-Wah Tan,
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Kew C, Huang W, Fischer J, Ganesan R, Robinson N, Antebi A. Evolutionarily conserved regulation of immunity by the splicing factor RNP-6/PUF60. eLife 2020; 9:57591. [PMID: 32538777 PMCID: PMC7332298 DOI: 10.7554/elife.57591] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/14/2020] [Indexed: 12/25/2022] Open
Abstract
Splicing is a vital cellular process that modulates important aspects of animal physiology, yet roles in regulating innate immunity are relatively unexplored. From genetic screens in C. elegans, we identified splicing factor RNP-6/PUF60 whose activity suppresses immunity, but promotes longevity, suggesting a tradeoff between these processes. Bacterial pathogen exposure affects gene expression and splicing in a rnp-6 dependent manner, and rnp-6 gain and loss-of-function activities reveal an active role in immune regulation. Another longevity promoting splicing factor, SFA-1, similarly exerts an immuno-suppressive effect, working downstream or parallel to RNP-6. RNP-6 acts through TIR-1/PMK-1/MAPK signaling to modulate immunity. The mammalian homolog, PUF60, also displays anti-inflammatory properties, and its levels swiftly decrease after bacterial infection in mammalian cells, implying a role in the host response. Altogether our findings demonstrate an evolutionarily conserved modulation of immunity by specific components of the splicing machinery.
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Affiliation(s)
- Chun Kew
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Wenming Huang
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Julia Fischer
- Department I of Internal Medicine, University of Cologne, Cologne, Germany.,Division of Infectious Diseases, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), Cologne, Germany
| | - Raja Ganesan
- Cellular-Stress and Immune Response Laboratory, Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Nirmal Robinson
- Cellular-Stress and Immune Response Laboratory, Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Adam Antebi
- Max Planck Institute for Biology of Ageing, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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Cheung PHH, Lee TWT, Kew C, Chen H, Yuen KY, Chan CP, Jin DY. Virus subtype-specific suppression of MAVS aggregation and activation by PB1-F2 protein of influenza A (H7N9) virus. PLoS Pathog 2020; 16:e1008611. [PMID: 32511263 PMCID: PMC7302872 DOI: 10.1371/journal.ppat.1008611] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 06/18/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022] Open
Abstract
Human infection with avian influenza A (H5N1) and (H7N9) viruses causes severe respiratory diseases. PB1-F2 protein is a critical virulence factor that suppresses early type I interferon response, but the mechanism of its action in relation to high pathogenicity is not well understood. Here we show that PB1-F2 protein of H7N9 virus is a particularly potent suppressor of antiviral signaling through formation of protein aggregates on mitochondria and inhibition of TRIM31-MAVS interaction, leading to prevention of K63-polyubiquitination and aggregation of MAVS. Unaggregated MAVS accumulated on fragmented mitochondria is prone to degradation by both proteasomal and lysosomal pathways. These properties are proprietary to PB1-F2 of H7N9 virus but not shared by its counterpart in WSN virus. A recombinant virus deficient of PB1-F2 of H7N9 induces more interferon β in infected cells. Our findings reveal a subtype-specific mechanism for destabilization of MAVS and suppression of interferon response by PB1-F2 of H7N9 virus. Exactly why avian influenza A (H5N1) and (H7N9) viruses cause severe diseases in humans remains unclear. PB1-F2 protein encoded by influenza A virus is one virulence factor that might make a difference. In this study we show that PB1-F2 protein of H7N9 virus is particularly strong in the suppression of host antiviral defense. This was achieved by inhibiting a key protein in cell signaling named MAVS. PB1-F2 directs MAVS for degradation and prevents MAVS from forming protein aggregates required for full activation. A recombinant virus in which PB1-F2 of H7N9 has been deleted can activate host antiviral response robustly. Our findings reveal a novel mechanism by which PB1-F2 protein of H7N9 virus prevents MAVS aggregation and promotes MAVS degradation, leading to the suppression of host antiviral defense.
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Affiliation(s)
| | | | - Chun Kew
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Honglin Chen
- State Key Laboratory for Emerging Infectious Diseases and Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kwok-Yung Yuen
- State Key Laboratory for Emerging Infectious Diseases and Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
- * E-mail: (CPC); (DYJ)
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
- * E-mail: (CPC); (DYJ)
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Tiku V, Kew C, Mehrotra P, Ganesan R, Robinson N, Antebi A. Nucleolar fibrillarin is an evolutionarily conserved regulator of bacterial pathogen resistance. Nat Commun 2018; 9:3607. [PMID: 30190478 PMCID: PMC6127302 DOI: 10.1038/s41467-018-06051-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 07/19/2018] [Indexed: 02/04/2023] Open
Abstract
Innate immunity is the first line of defense against infections. Pathways regulating innate responses can also modulate other processes, including stress resistance and longevity. Increasing evidence suggests a role for the nucleolus in regulating cellular processes implicated in health and disease. Here we show the highly conserved nucleolar protein, fibrillarin, is a vital factor regulating pathogen resistance. Fibrillarin knockdown enhances resistance in C. elegans against bacterial pathogens, higher levels of fibrillarin induce susceptibility to infection. Pathogenic infection reduces nucleolar size, ribsosomal RNA, and fibrillarin levels. Genetic epistasis reveals fibrillarin functions independently of the major innate immunity mediators, suggesting novel mechanisms of pathogen resistance. Bacterial infection also reduces nucleolar size and fibrillarin levels in mammalian cells. Fibrillarin knockdown prior to infection increases intracellular bacterial clearance, reduces inflammation, and enhances cell survival. Collectively, these findings reveal an evolutionarily conserved role of fibrillarin in infection resistance and suggest the nucleolus as a focal point in innate immune responses.
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Affiliation(s)
- Varnesh Tiku
- Max Planck Institute for Biology of Ageing, Joseph Stelzmann Strasse 9b, 50931, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50674, Cologne, Germany.,Department of Infectious Diseases, Genentech Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Chun Kew
- Max Planck Institute for Biology of Ageing, Joseph Stelzmann Strasse 9b, 50931, Cologne, Germany
| | - Parul Mehrotra
- Max Planck Institute for Biology of Ageing, Joseph Stelzmann Strasse 9b, 50931, Cologne, Germany.,VIB-Center for Inflammation Research, VIB - Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Raja Ganesan
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50674, Cologne, Germany.,Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, 50674, Cologne, Germany
| | - Nirmal Robinson
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50674, Cologne, Germany. .,Centre for Cancer Biology, University of South Australia, HB11-35 UniSA CRI Building, North Terrace, 5001, Adelaide, Australia.
| | - Adam Antebi
- Max Planck Institute for Biology of Ageing, Joseph Stelzmann Strasse 9b, 50931, Cologne, Germany. .,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50674, Cologne, Germany.
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6
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Kew C, Lui PY, Chan CP, Jin DY, Kok KH. Inhibition of RIG-I-dependent innate immunity by herpes simplex virus type I Us11 protein. Hong Kong Med J 2016; 22 Suppl 7:46-47. [PMID: 29941695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Affiliation(s)
- C Kew
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong
| | - P Y Lui
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong
| | - C P Chan
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong
| | - D Y Jin
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong
| | - K H Kok
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong
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Chan CP, Yuen CK, Fung SY, Kew C, Yuen KY, Kok KH, Jin DY. Antagonising roles between PACT and influenza A virus polymerase subunits in viral replication and innate immune response. The Journal of Immunology 2016. [DOI: 10.4049/jimmunol.196.supp.132.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Interplay between host innate immune responses and viral antagonism determines the effectiveness of viral replication and pathogenicity. Influenza A virus (IAV) confronts host antiviral responses including type I interferon production using multiple viral proteins such as NS1. We have previously shown that double stranded RNA-binding protein PACT is an essential coactivator of RIG-I in innate antiviral response. In this study, we have further shown that PACT has dual antiviral activity in both interferon-dependent and interferon-independent manners. We found that antiviral activity of PACT is mediated through not only the activation of RIG-I and interferon production but also the direct suppression of IAV polymerase activity. We found that PACT associates with IAV polymerase subunits, namely PB2, PB1 and PA, and inhibits viral replication. On the other hand, the three polymerase subunits also counteract PACT/RIG-I-mediated production of type-I interferon. Taken together, our findings reveal a new mechanism of virus-host interaction demonstrating the mutual antagonism between PACT and IAV polymerases during IAV infection and replication.
Supported by RGC (HKU1/CRF/11G, N-HKU712/12, T11-707/15-R and C7011-15R), HMRF (12111312, 14130862, HKM-15-M01 and 15140662) and S. K. Yee MRF (2011).
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Ho TH, Kew C, Lui PY, Chan CP, Satoh T, Akira S, Jin DY, Kok KH. PACT- and RIG-I-Dependent Activation of Type I Interferon Production by a Defective Interfering RNA Derived from Measles Virus Vaccine. J Virol 2016; 90:1557-68. [PMID: 26608320 PMCID: PMC4719617 DOI: 10.1128/jvi.02161-15] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 11/17/2015] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED The live attenuated measles virus vaccine is highly immunostimulatory. Identification and characterization of its components that activate the innate immune response might provide new strategies and agents for the rational design and development of chemically defined adjuvants. In this study, we report on the activation of type I interferon (IFN) production by a defective interfering (DI) RNA isolated from the Hu-191 vaccine strain of measles virus. We found that the Hu-191 virus induced IFN-β much more potently than the Edmonston strain. In the search for IFN-inducing species in Hu-191, we identified a DI RNA specifically expressed by this strain. This DI RNA, which was of the copy-back type, was predicted to fold into a hairpin structure with a long double-stranded stem region of 206 bp, and it potently induced the expression of IFN-β. Its IFN-β-inducing activity was further enhanced when both cytoplasmic RNA sensor RIG-I and its partner, PACT, were overexpressed. On the contrary, this activity was abrogated in cells deficient in PACT or RIG-I. The DI RNA was found to be associated with PACT in infected cells. In addition, both the 5'-di/triphosphate end and the double-stranded stem region on the DI RNA were essential for its activation of PACT and RIG-I. Taken together, our findings support a model in which a viral DI RNA is sensed by PACT and RIG-I to initiate an innate antiviral response. Our work might also provide a foundation for identifying physiological PACT ligands and developing novel adjuvants or antivirals. IMPORTANCE The live attenuated measles virus vaccine is one of the most successful human vaccines and has largely contained the devastating impact of a highly contagious virus. Identifying the components in this vaccine that stimulate the host immune response and understanding their mechanism of action might help to design and develop better adjuvants, vaccines, antivirals, and immunotherapeutic agents. We identified and characterized a defective interfering RNA from the Hu-191 vaccine strain of measles virus which has safely been used in millions of people for many years. We further demonstrated that this RNA potently induces an antiviral immune response through cellular sensors of viral RNA known as PACT and RIG-I. Similar types of viral RNA that bind with and activate PACT and RIG-I might retain the immunostimulatory property of measles virus vaccines but would not induce adaptive immunity. They are potentially useful as chemically defined vaccine adjuvants, antivirals, and immunostimulatory agents.
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Affiliation(s)
- Ting-Hin Ho
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chun Kew
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Pak-Yin Lui
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Takashi Satoh
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Shizuo Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kin-Hang Kok
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
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Jowsey SG, Jacobs C, Gross CR, Hong BA, Messersmith EE, Gillespie BW, Beebe TJ, Kew C, Matas A, Yusen RD, Hill-Callahan M, Odim J, Taler SJ. Emotional well-being of living kidney donors: findings from the RELIVE Study. Am J Transplant 2014; 14:2535-44. [PMID: 25293374 PMCID: PMC4205186 DOI: 10.1111/ajt.12906] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 06/27/2014] [Accepted: 06/28/2014] [Indexed: 01/25/2023]
Abstract
Following kidney donation, short-term quality of life outcomes compare favorably to US normative data but long-term effects on mood are not known. In the Renal and Lung Living Donors Evaluation Study (RELIVE), records from donations performed 1963-2005 were reviewed for depression and antidepressant use predonation. Postdonation, in a cross-sectional cohort design 2010-2012, donors completed the Patient Health Questionnaire (PHQ-9) depression screening instrument, the Life Orientation Test-Revised, 36-Item Short Form Health Survey and donation experience questions. Of 6909 eligible donors, 3470 were contacted and 2455 participated (71%). The percent with depressive symptoms (8%; PHQ-9>10) was similar to National Health and Nutrition Examination Survey participants (7%, p=0.30). Predonation psychiatric disorders were more common in unrelated than related donors (p=0.05). Postdonation predictors of depressive symptoms included nonwhite race OR=2.00, p=0.020), younger age at donation (OR=1.33 per 10 years, p=0.002), longer recovery time from donation (OR=1.74, p=0.0009), greater financial burden (OR=1.32, p=0.013) and feeling morally obligated to donate (OR=1.23, p=0.003). While cross-sectional prevalence of depression is comparable to population normative data, some factors identifiable around time of donation, including longer recovery, financial stressors, younger age and moral obligation to donate may identify donors more likely to develop future depression, providing an opportunity for intervention.
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Affiliation(s)
- SG Jowsey
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN,The William J. von Liebig Transplant Center, Mayo Clinic, Rochester, MN
| | - C Jacobs
- College of Pharmacy and School of Nursing, University of Minnesota, Minneapolis, MN
| | - CR Gross
- College of Pharmacy and School of Nursing, University of Minnesota, Minneapolis, MN
| | - BA Hong
- Washington University School of Medicine, St. Louis, MO
| | | | - BW Gillespie
- Department of Biostatistics, University of Michigan, Ann Arbor, MI
| | - TJ Beebe
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | - C Kew
- University of Alabama at Birmingham, Birmingham, AL
| | - A Matas
- University of Minnesota, Minneapolis, MN
| | - RD Yusen
- Washington University School of Medicine, St. Louis, MO
| | | | - J Odim
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - SJ Taler
- The William J. von Liebig Transplant Center, Mayo Clinic, Rochester, MN,Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
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Siu KL, Yeung ML, Kok KH, Yuen KS, Kew C, Lui PY, Chan CP, Tse H, Woo PCY, Yuen KY, Jin DY. Middle east respiratory syndrome coronavirus 4a protein is a double-stranded RNA-binding protein that suppresses PACT-induced activation of RIG-I and MDA5 in the innate antiviral response. J Virol 2014; 88:4866-76. [PMID: 24522921 PMCID: PMC3993821 DOI: 10.1128/jvi.03649-13] [Citation(s) in RCA: 159] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/07/2014] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging pathogen that causes severe disease in human. MERS-CoV is closely related to bat coronaviruses HKU4 and HKU5. Evasion of the innate antiviral response might contribute significantly to MERS-CoV pathogenesis, but the mechanism is poorly understood. In this study, we characterized MERS-CoV 4a protein as a novel immunosuppressive factor that antagonizes type I interferon production. MERS-CoV 4a protein contains a double-stranded RNA-binding domain capable of interacting with poly(I · C). Expression of MERS-CoV 4a protein suppressed the interferon production induced by poly(I · C) or Sendai virus. RNA binding of MERS-CoV 4a protein was required for IFN antagonism, a property shared by 4a protein of bat coronavirus HKU5 but not by the counterpart in bat coronavirus HKU4. MERS-CoV 4a protein interacted with PACT in an RNA-dependent manner but not with RIG-I or MDA5. It inhibited PACT-induced activation of RIG-I and MDA5 but did not affect the activity of downstream effectors such as RIG-I, MDA5, MAVS, TBK1, and IRF3. Taken together, our findings suggest a new mechanism through which MERS-CoV employs a viral double-stranded RNA-binding protein to circumvent the innate antiviral response by perturbing the function of cellular double-stranded RNA-binding protein PACT. PACT targeting might be a common strategy used by different viruses, including Ebola virus and herpes simplex virus 1, to counteract innate immunity. IMPORTANCE Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging and highly lethal human pathogen. Why MERS-CoV causes severe disease in human is unclear, and one possibility is that MERS-CoV is particularly efficient in counteracting host immunity, including the sensing of virus invasion. It will therefore be critical to clarify how MERS-CoV cripples the host proteins that sense viruses and to compare MERS-CoV with its ancestral viruses in bats in the counteraction of virus sensing. This work not only provides a new understanding of the abilities of MERS-CoV and closely related bat viruses to subvert virus sensing but also might prove useful in revealing new strategies for the development of vaccines and antivirals.
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Affiliation(s)
- Kam-Leung Siu
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Man Lung Yeung
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Kin-Hang Kok
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Kit-San Yuen
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Chun Kew
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Pak-Yin Lui
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
| | - Herman Tse
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Patrick C. Y. Woo
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Kwok-Yung Yuen
- Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong
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11
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Kew C, Macnab GM. The dentist and hepatitis-B virus infection: three-way traffic in the dental surgery. J Dent Assoc S Afr 1979; 34:15-20. [PMID: 296592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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13
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