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Xiang Q, Yang Z, Nicholas J. STAT and Janus kinase targeting by human herpesvirus 8 interferon regulatory factor in the suppression of type-I interferon signaling. PLoS Pathog 2022; 18:e1010676. [PMID: 35776779 PMCID: PMC9307175 DOI: 10.1371/journal.ppat.1010676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 07/22/2022] [Accepted: 06/15/2022] [Indexed: 11/18/2022] Open
Abstract
Human herpesvirus 8 (HHV-8), also known as Kaposi’s sarcoma (KS)-associated herpesvirus, is involved etiologically in AIDS-associated KS, primary effusion lymphoma (PEL), and multicentric Castleman’s disease, in which both viral latent and lytic functions are important. HHV-8 encodes four viral interferon regulatory factors (vIRFs) that are believed to contribute to viral latency (in PEL cells, at least) and/or to productive replication via suppression of cellular antiviral and stress signaling. Here, we identify vIRF-1 interactions with signal transducer and activator of transcription (STAT) factors 1 and 2, interferon (IFN)-stimulated gene factor 3 (ISGF3) cofactor IRF9, and associated signal transducing Janus kinases JAK1 and TYK2. In naturally infected PEL cells and in iSLK epithelial cells infected experimentally with genetically engineered HHV-8, vIRF-1 depletion or ablation, respectively, led to increased levels of active (phosphorylated) STAT1 and STAT2 in IFNβ-treated, and untreated, cells during lytic replication and to associated cellular-gene induction. In transfected 293T cells, used for mechanistic studies, suppression by vIRF-1 of IFNβ-induced phospho-STAT1 (pSTAT1) was found to be highly dependent on STAT2, indicating vIRF-1-mediated inhibition and/or dissociation of ISGF3-complexing, resulting in susceptibility of pSTAT1 to inactivating dephosphorylation. Indeed, coprecipitation experiments involving targeted precipitation of ISGF3 components identified suppression of mutual interactions by vIRF-1. In contrast, suppression of IFNβ-induced pSTAT2 was effected by regulation of STAT2 activation, likely via detected inhibition of TYK2 and its interactions with STAT2 and IFN type-I receptor (IFNAR). Our identified vIRF-1 interactions with IFN-signaling mediators STATs 1 and 2, co-interacting ISGF3 component IRF9, and STAT-activating TYK2 and the suppression of IFN signaling via ISGF3, TYK2-STAT2 and TYK2-IFNAR disruption and TYK2 inhibition represent novel mechanisms of vIRF function and HHV-8 evasion from host-cell defenses. Viral interferon regulatory factors (vIRFs) encoded by Kaposi’s sarcoma- and lymphoma-associated human herpesvirus 8 (HHV-8) are mediators of protection from cellular antiviral responses and therefore are considered to be pivotal for successful de novo infection, latency establishment and maintenance, and productive (lytic) replication. Identification and characterization of their interactions with cellular proteins, the functional consequences of these interactions, and the operation of these mechanisms in the context of infection has the potential to enable the development of novel antiviral strategies targeted to these interactions and mechanisms. In this report we identify vIRF-1 interactions with transcription factors STAT1 and STAT2, the co-interacting component, IRF9, of the antiviral interferon (IFN)-induced transcription complex ISGF3, and the ability of vIRF-1 to inhibit activation and functional associations of IFN-I receptor- and STAT1/2-kinase TYK2, suppress STAT1/2 activation, and dissociate STAT1 from IFN-induced ISGF3 to blunt IFN signaling and promote STAT1 inactivation. These interactions and activities, which mediate suppression of innate cellular defenses against virus replication, represent novel properties among vIRFs and could potentially be exploited for antiviral and therapeutic purposes.
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Affiliation(s)
- Qiwang Xiang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Zunlin Yang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - John Nicholas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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2
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Xiong Y, Tang YD, Zheng C. The crosstalk between the caspase family and the cGAS‒STING signaling pathway. J Mol Cell Biol 2021; 13:739-747. [PMID: 34718659 PMCID: PMC8718194 DOI: 10.1093/jmcb/mjab071] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 11/13/2022] Open
Abstract
Edited by Jiarui Wu Cytosolic nucleic acid sensors are critical for sensing nucleic acids and initiating innate immunity during microbial infections and/or cell death. Over the last decade, several key studies have characterized the conserved mechanism of cyclic guanosine monophosphate‒adenosine monophosphate synthase (cGAS) and the downstream signaling adaptor stimulator of interferon genes (STING) initiating the innate immune signaling pathways. Aside from its primary involvement in microbial infections and inflammatory diseases, there is growing interest in the alternate roles of cGAS‒STING-mediated signaling. Caspase family members are powerful functional proteins that respond to cellular stress, including cell death signals, inflammation, and innate immunity. Recent studies have uncovered how the caspase family cooperates with the cGAS‒STING signaling pathway. Most caspase family members negatively regulate the cGAS‒STING signaling pathway. In turn, some caspase family members can also be modulated by cGAS‒STING. This review gives a detailed account of the interplay between the caspase family and the cGAS‒STING signaling pathway, which will shed light on developing novel therapeutics targeting the caspase family and cGAS‒STING signaling in antiviral innate immunity, cancer, inflammatory, and autoimmunity.
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Affiliation(s)
- Yongai Xiong
- Department of Pharmaceutics, Key Laboratory of Basic Pharmacology of Guizhou Province and School of Pharmacy, Zunyi Medical University, Zunyi, China.,Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Yan-Dong Tang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.,State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 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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3
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Choi YB, Cousins E, Nicholas J. Novel Functions and Virus-Host Interactions Implicated in Pathogenesis and Replication of Human Herpesvirus 8. Recent Results Cancer Res 2021; 217:245-301. [PMID: 33200369 DOI: 10.1007/978-3-030-57362-1_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Human herpesvirus 8 (HHV-8) is classified as a γ2-herpesvirus and is related to Epstein-Barr virus (EBV), a γ1-herpesvirus. One important aspect of the γ-herpesviruses is their association with neoplasia, either naturally or in animal model systems. HHV-8 is associated with B-cell-derived primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD), endothelial-derived Kaposi's sarcoma (KS), and KSHV inflammatory cytokine syndrome (KICS). EBV is also associated with a number of B-cell malignancies, such as Burkitt's lymphoma, Hodgkin's lymphoma, and posttransplant lymphoproliferative disease, in addition to epithelial nasopharyngeal and gastric carcinomas. Despite the similarities between these viruses and their associated malignancies, the particular protein functions and activities involved in key aspects of virus biology and neoplastic transformation appear to be quite distinct. Indeed, HHV-8 specifies a number of proteins for which counterparts had not previously been identified in EBV, other herpesviruses, or even viruses in general, and these proteins are believed to play vital functions in virus biology and to be involved centrally in viral pathogenesis. Additionally, a set of microRNAs encoded by HHV-8 appears to modulate the expression of multiple host proteins to provide conditions conductive to virus persistence within the host and possibly contributing to HHV-8-induced neoplasia. Here, we review the molecular biology underlying these novel virus-host interactions and their potential roles in both virus biology and virus-associated disease.
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Affiliation(s)
- Young Bong Choi
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, 1650 Orleans Street, Baltimore, MD, 21287, USA.
| | - Emily Cousins
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, 1650 Orleans Street, Baltimore, MD, 21287, USA
| | - John Nicholas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, 1650 Orleans Street, Baltimore, MD, 21287, USA
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4
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Abstract
Viruses commonly antagonize the antiviral type I interferon response by targeting signal transducer and activator of transcription 1 (STAT1) and STAT2, key mediators of interferon signaling. Other STAT family members mediate signaling by diverse cytokines important to infection, but their relationship with viruses is more complex. Importantly, virus-STAT interaction can be antagonistic or stimulatory depending on diverse viral and cellular factors. While STAT antagonism can suppress immune pathways, many viruses promote activation of specific STATs to support viral gene expression and/or produce cellular conditions conducive to infection. It is also becoming increasingly clear that viruses can hijack noncanonical STAT functions to benefit infection. For a number of viruses, STAT function is dynamically modulated through infection as requirements for replication change. Given the critical role of STATs in infection by diverse viruses, the virus-STAT interface is an attractive target for the development of antivirals and live-attenuated viral vaccines. Here, we review current understanding of the complex and dynamic virus-STAT interface and discuss how this relationship might be harnessed for medical applications.
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5
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Bojagora A, Saridakis V. USP7 manipulation by viral proteins. Virus Res 2020; 286:198076. [DOI: 10.1016/j.virusres.2020.198076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 05/14/2020] [Accepted: 06/24/2020] [Indexed: 01/27/2023]
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Saeed AFUH, Ruan X, Guan H, Su J, Ouyang S. Regulation of cGAS-Mediated Immune Responses and Immunotherapy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1902599. [PMID: 32195086 PMCID: PMC7080523 DOI: 10.1002/advs.201902599] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/14/2020] [Indexed: 05/08/2023]
Abstract
Early detection of infectious nucleic acids released from invading pathogens by the innate immune system is critical for immune defense. Detection of these nucleic acids by host immune sensors and regulation of DNA sensing pathways have been significant interests in the past years. Here, current understandings of evolutionarily conserved DNA sensing cyclic GMP-AMP (cGAMP) synthase (cGAS) are highlighted. Precise activation and tight regulation of cGAS are vital in appropriate innate immune responses, senescence, tumorigenesis and immunotherapy, and autoimmunity. Hence, substantial insights into cytosolic DNA sensing and immunotherapy of indispensable cytosolic sensors have been detailed to extend limited knowledge available thus far. This Review offers a critical, in-depth understanding of cGAS regulation, cytosolic DNA sensing, and currently established therapeutic approaches of essential cytosolic immune agents for improved human health.
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Affiliation(s)
- Abdullah F. U. H. Saeed
- The Key Laboratory of Innate Immune Biology of Fujian ProvinceProvincial University Key Laboratory of Cellular Stress Response and Metabolic RegulationBiomedical Research Center of South ChinaKey Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of EducationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
- Fujian Key Laboratory of Special Marine Bio‐resources Sustainable UtilizationThe Public Service Platform for Industrialization Development Technology of Marine Biological Medicine and Product of State Oceanic AdministrationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
- Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and Technology (Qingdao)Qingdao266237China
- College of Chemistry and Materials ScienceFujian Normal UniversityFuzhou350117China
| | - Xinglin Ruan
- Department of NeurologyFujian Medical University Union Hospital29 Xinquan Road Gulou DistrictFuzhou350001China
| | - Hongxin Guan
- The Key Laboratory of Innate Immune Biology of Fujian ProvinceProvincial University Key Laboratory of Cellular Stress Response and Metabolic RegulationBiomedical Research Center of South ChinaKey Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of EducationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
- Fujian Key Laboratory of Special Marine Bio‐resources Sustainable UtilizationThe Public Service Platform for Industrialization Development Technology of Marine Biological Medicine and Product of State Oceanic AdministrationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
| | - Jingqian Su
- The Key Laboratory of Innate Immune Biology of Fujian ProvinceProvincial University Key Laboratory of Cellular Stress Response and Metabolic RegulationBiomedical Research Center of South ChinaKey Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of EducationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
- Fujian Key Laboratory of Special Marine Bio‐resources Sustainable UtilizationThe Public Service Platform for Industrialization Development Technology of Marine Biological Medicine and Product of State Oceanic AdministrationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
| | - Songying Ouyang
- The Key Laboratory of Innate Immune Biology of Fujian ProvinceProvincial University Key Laboratory of Cellular Stress Response and Metabolic RegulationBiomedical Research Center of South ChinaKey Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of EducationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
- Fujian Key Laboratory of Special Marine Bio‐resources Sustainable UtilizationThe Public Service Platform for Industrialization Development Technology of Marine Biological Medicine and Product of State Oceanic AdministrationCollege of Life SciencesFujian Normal UniversityFuzhou350117China
- Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and Technology (Qingdao)Qingdao266237China
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7
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Golas G, Jang SJ, Naik NG, Alonso JD, Papp B, Toth Z. Comparative analysis of the viral interferon regulatory factors of KSHV for their requisite for virus production and inhibition of the type I interferon pathway. Virology 2019; 541:160-173. [PMID: 32056714 DOI: 10.1016/j.virol.2019.12.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/19/2019] [Accepted: 12/27/2019] [Indexed: 01/23/2023]
Abstract
Unique among human viruses, Kaposi's sarcoma-associated herpesvirus (KSHV) encodes several homologs of cellular interferon regulatory factors (vIRFs). Since KSHV expresses multiple factors that can inhibit interferon (IFN) signaling to promote virus production, it is still unclear to what extent vIRFs contribute to these specific processes during KSHV infection. To study the function of vIRFs during viral infection, we engineered 3xFLAG-tagged-vIRF and vIRF-knockout recombinant KSHV clones, which were utilized to test vIRF expression, as well as their requirement for viral replication, virus production, and inhibition of the type I IFN pathway in different models of lytic KSHV infection. Our data show that all vIRFs can be expressed as lytic viral proteins, yet were dispensable for KSHV production and inhibition of type I IFN. Nevertheless, as vIRFs were able to suppress IFN-stimulated antiviral genes, vIRFs may still promote the KSHV lytic cycle in the presence of an ongoing antiviral response.
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Affiliation(s)
- Gavin Golas
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Seung Jin Jang
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Nenavath Gopal Naik
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Juan D Alonso
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Bernadett Papp
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA; UF Genetics Institute, Gainesville, FL, 32610, USA; UF Health Cancer Center, Gainesville, FL, 32610, USA; UF Informatics Institute, Gainesville, FL, 32610, USA
| | - Zsolt Toth
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA; UF Genetics Institute, Gainesville, FL, 32610, USA; UF Health Cancer Center, Gainesville, FL, 32610, USA.
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8
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Koch S, Damas M, Freise A, Hage E, Dhingra A, Rückert J, Gallo A, Kremmer E, Tegge W, Brönstrup M, Brune W, Schulz TF. Kaposi's sarcoma-associated herpesvirus vIRF2 protein utilizes an IFN-dependent pathway to regulate viral early gene expression. PLoS Pathog 2019; 15:e1007743. [PMID: 31059555 PMCID: PMC6522069 DOI: 10.1371/journal.ppat.1007743] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 05/16/2019] [Accepted: 03/31/2019] [Indexed: 12/14/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) belongs to the subfamily of Gammaherpesvirinae and is the etiological agent of Kaposi’s sarcoma as well as of two lymphoproliferative diseases: primary effusion lymphoma and multicentric Castleman disease. The KSHV life cycle is divided into a latent and a lytic phase and is highly regulated by viral immunomodulatory proteins which control the host antiviral immune response. Among them is a group of proteins with homology to cellular interferon regulatory factors, the viral interferon regulatory factors 1–4. The KSHV vIRFs are known as inhibitors of cellular interferon signaling and are involved in different oncogenic pathways. Here we characterized the role of the second vIRF protein, vIRF2, during the KSHV life cycle. We found the vIRF2 protein to be expressed in different KSHV positive cells with early lytic kinetics. Importantly, we observed that vIRF2 suppresses the expression of viral early lytic genes in both newly infected and reactivated persistently infected endothelial cells. This vIRF2-dependent regulation of the KSHV life cycle might involve the increased expression of cellular interferon-induced genes such as the IFIT proteins 1, 2 and 3, which antagonize the expression of early KSHV lytic proteins. Our findings suggest a model in which the viral protein vIRF2 allows KSHV to harness an IFN-dependent pathway to regulate KSHV early gene expression. The life cycle of Kaposi Sarcoma herpesvirus involves both persistence in a latent form and productive replication to generate new viral particles. How the virus switches between latency and productive (‘lytic’) replication is only partially understood. Here we show that a viral homologue of interferon regulatory factors, vIRF2, antagonizes lytic protein expression in endothelial cells. It does this by inducing the expression of cellular interferon-regulated genes such as IFIT 1–3, which in turn dampens early viral gene expression. This observation suggests that vIRF2 allows KSHV to harness the interferon pathway to regulate early viral gene expression in endothelial cells.
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Affiliation(s)
- Sandra Koch
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Modester Damas
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Anika Freise
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Elias Hage
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Akshay Dhingra
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Jessica Rückert
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Antonio Gallo
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
- German Centre for Infection Research, Hamburg Site, Germany
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, Helmholtz Centre Munich, German Research Center for Environmental Health, Munich, Germany
| | - Werner Tegge
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Mark Brönstrup
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Wolfram Brune
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
- German Centre for Infection Research, Hamburg Site, Germany
| | - Thomas F. Schulz
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
- * E-mail:
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9
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He B, Tran JT, Sanchez DJ. Manipulation of Type I Interferon Signaling by HIV and AIDS-Associated Viruses. J Immunol Res 2019; 2019:8685312. [PMID: 31089479 PMCID: PMC6476103 DOI: 10.1155/2019/8685312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 02/14/2019] [Indexed: 12/20/2022] Open
Abstract
Type I Interferons were first described for their profound antiviral abilities in cell culture and animal models, and later, they were translated into potent antiviral therapeutics. However, as additional studies into the function of Type I Interferons progressed, it was also seen that pathogenic viruses have coevolved to encode potent mechanisms allowing them to evade or suppress the impact of Type I Interferons on their replication. For chronic viral infections, such as HIV and many of the AIDS-associated viruses, including HTLV, HCV, KSHV, and EBV, the clinical efficacy of Type I Interferons is limited by these mechanisms. Here, we review some of the ways that HIV and AIDS-associated viruses thrive in Type I Interferon-rich environments via mechanisms that block the function of this important antiviral cytokine. Overall, a better understanding of these mechanisms creates avenues to better understand the innate immune response to these viruses as well as plan the development of antivirals that would allow the natural antiviral effect of Type I Interferons to manifest during these infections.
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Affiliation(s)
- Buyuan He
- Pharmaceutical Sciences Department, College of Pharmacy, Western University of Health Sciences, Pomona 91766, California, USA
| | - James T. Tran
- Pharmaceutical Sciences Department, College of Pharmacy, Western University of Health Sciences, Pomona 91766, California, USA
| | - David Jesse Sanchez
- Pharmaceutical Sciences Department, College of Pharmacy, Western University of Health Sciences, Pomona 91766, California, USA
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10
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Mariggiò G, Koch S, Schulz TF. Kaposi sarcoma herpesvirus pathogenesis. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0275. [PMID: 28893942 PMCID: PMC5597742 DOI: 10.1098/rstb.2016.0275] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2017] [Indexed: 12/15/2022] Open
Abstract
Kaposi sarcoma herpesvirus (KSHV), taxonomical name human gammaherpesvirus 8, is a phylogenetically old human virus that co-evolved with human populations, but is now only common (seroprevalence greater than 10%) in sub-Saharan Africa, around the Mediterranean Sea, parts of South America and in a few ethnic communities. KSHV causes three human malignancies, Kaposi sarcoma, primary effusion lymphoma, and many cases of the plasmablastic form of multicentric Castleman's disease (MCD) as well as occasional cases of plasmablastic lymphoma arising from MCD; it has also been linked to rare cases of bone marrow failure and hepatitis. As it has colonized humans physiologically for many thousand years, cofactors are needed to allow it to unfold its pathogenic potential. In most cases, these include immune defects of genetic, iatrogenic or infectious origin, and inflammation appears to play an important role in disease development. Our much improved understanding of its life cycle and its role in pathogenesis should now allow us to develop new therapeutic strategies directed against key viral proteins or intracellular pathways that are crucial for virus replication or persistence. Likewise, its limited (for a herpesvirus) distribution and transmission should offer an opportunity for the development and use of a vaccine to prevent transmission. This article is part of the themed issue ‘Human oncogenic viruses’.
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Affiliation(s)
- Giuseppe Mariggiò
- Institute of Virology, Hannover Medical School, Carl Neuberg Strasse 1, 30625 Hannover, Germany.,German Centre for Infection Research, Hannover-Braunschweig site, Hannover, Germany
| | - Sandra Koch
- Institute of Virology, Hannover Medical School, Carl Neuberg Strasse 1, 30625 Hannover, Germany.,German Centre for Infection Research, Hannover-Braunschweig site, Hannover, Germany
| | - Thomas F Schulz
- Institute of Virology, Hannover Medical School, Carl Neuberg Strasse 1, 30625 Hannover, Germany .,German Centre for Infection Research, Hannover-Braunschweig site, Hannover, Germany
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11
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Role of Pattern Recognition Receptors in KSHV Infection. Cancers (Basel) 2018; 10:cancers10030085. [PMID: 29558453 PMCID: PMC5876660 DOI: 10.3390/cancers10030085] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 03/12/2018] [Accepted: 03/16/2018] [Indexed: 02/06/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus or Human herpesvirus-8 (KSHV/HHV-8), an oncogenic human herpesvirus and the leading cause of cancer in HIV-infected individuals, is a major public health concern with recurring reports of epidemics on a global level. The early detection of KSHV virus and subsequent activation of the antiviral immune response by the host’s immune system are crucial to prevent KSHV infection. The host’s immune system is an evolutionary conserved system that provides the most important line of defense against invading microbial pathogens, including viruses. Viruses are initially detected by the cells of the host innate immune system, which evoke concerted antiviral responses via the secretion of interferons (IFNs) and inflammatory cytokines/chemokines for elimination of the invaders. Type I IFN and cytokine gene expression are regulated by multiple intracellular signaling pathways that are activated by germline-encoded host sensors, i.e., pattern recognition receptors (PRRs) that recognize a conserved set of ligands, known as ‘pathogen-associated molecular patterns (PAMPs)’. On the contrary, persistent and dysregulated signaling of PRRs promotes numerous tumor-causing inflammatory events in various human cancers. Being an integral component of the mammalian innate immune response and due to their constitutive activation in tumor cells, targeting PRRs appears to be an effective strategy for tumor prevention and/or treatment. Cellular PRRs are known to respond to KSHV infection, and KSHV has been shown to be armed with an array of strategies to selectively inhibit cellular PRR-based immune sensing to its benefit. In particular, KSHV has acquired specific immunomodulatory genes to effectively subvert PRR responses during the early stages of primary infection, lytic reactivation and latency, for a successful establishment of a life-long persistent infection. The current review aims to comprehensively summarize the latest advances in our knowledge of role of PRRs in KSHV infections.
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12
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Marsili G, Perrotti E, Remoli AL, Acchioni C, Sgarbanti M, Battistini A. IFN Regulatory Factors and Antiviral Innate Immunity: How Viruses Can Get Better. J Interferon Cytokine Res 2018; 36:414-32. [PMID: 27379864 DOI: 10.1089/jir.2016.0002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The interferon regulatory factor (IRF) family consists of transcriptional regulators that exert multifaceted and versatile functions in multiple biological processes. Their crucial role as central mediators in the establishment and execution of host immunity in response to pathogen-derived signals downstream pattern recognition receptors (PRRs) makes IRFs a hallmark of the host antiviral response. They function as hub molecules at the crossroad of different signaling pathways for the induction of interferon (IFN) and inflammatory cytokines, as well as of antiviral and immunomodulatory genes even in an IFN-independent manner. By regulating the development and activity of immune cells, IRFs also function as a bridge between innate and adaptive responses. As such, IRFs represent attractive and compulsive targets in viral strategies to subvert antiviral signaling. In this study, we discuss current knowledge on the wide array of strategies put in place by pathogenic viruses to evade, subvert, and/or hijack these essential components of host antiviral immunity.
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Affiliation(s)
- Giulia Marsili
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità , Rome, Italy
| | - Edvige Perrotti
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità , Rome, Italy
| | - Anna Lisa Remoli
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità , Rome, Italy
| | - Chiara Acchioni
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità , Rome, Italy
| | - Marco Sgarbanti
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità , Rome, Italy
| | - Angela Battistini
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità , Rome, Italy
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Watanabe T, Sugimoto A, Hosokawa K, Fujimuro M. Signal Transduction Pathways Associated with KSHV-Related Tumors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1045:321-355. [PMID: 29896674 DOI: 10.1007/978-981-10-7230-7_15] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Signal transduction pathways play a key role in the regulation of cell growth, cell differentiation, cell survival, apoptosis, and immune responses. Bacterial and viral pathogens utilize the cell signal pathways by encoding their own proteins or noncoding RNAs to serve their survival and replication in infected cells. Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), is classified as a rhadinovirus in the γ-herpesvirus subfamily and was the eighth human herpesvirus to be discovered from Kaposi's sarcoma specimens. KSHV is closely associated with an endothelial cell malignancy, Kaposi's sarcoma, and B-cell malignancies, primary effusion lymphoma, and multicentric Castleman's disease. Recent studies have revealed that KSHV manipulates the cellular signaling pathways to achieve persistent infection, viral replication, cell proliferation, anti-apoptosis, and evasion of immune surveillance in infected cells. This chapter summarizes recent developments in our understanding of the molecular mechanisms used by KSHV to interact with the cell signaling machinery.
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Affiliation(s)
- Tadashi Watanabe
- Department of Cell Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Atsuko Sugimoto
- Department of Cell Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Kohei Hosokawa
- Department of Cell Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Masahiro Fujimuro
- Department of Cell Biology, Kyoto Pharmaceutical University, Kyoto, Japan.
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Awazawa R, Utsumi D, Katano H, Awazawa T, Miyagi T, Hayashi K, Matori S, Uezato H, Takahashi K. High Prevalence of Distinct Human Herpesvirus 8 Contributes to the High Incidence of Non-acquired Immune Deficiency Syndrome-Associated Kaposi's Sarcoma in Isolated Japanese Islands. J Infect Dis 2017; 216:850-858. [PMID: 28968717 DOI: 10.1093/infdis/jix424] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 08/16/2017] [Indexed: 12/20/2022] Open
Abstract
Background Non-acquired immune deficiency syndrome (AIDS) Kaposi's sarcoma (KS) is extremely rare in Japan but highly endemic in Okinawa, especially in Miyako Islands. We aimed to elucidate the exact incidence and cause of this high prevalence. Methods Non-AIDS KS cases in Okinawa Prefecture over the past 31 years were reviewed, and human herpesvirus 8 (HHV8) seroprevalence in Miyako Islands was determined. We examined whole-genome sequences of 3 HHV8 strains and performed whole-exome sequencing of 4 male patients from Miyako Islands. Results Approximately half of the non-AIDS KS cases in Okinawa Prefecture were from Miyako Islands. The age-adjusted incidence rate was 0.87/105 per year for Miyako Islands and 0.056/105 per year for the rest of Okinawa. Human herpesvirus 8 seroprevalence was 15.4% in Miyako Islands. The 3 HHV8 genomes isolated from Miyako islanders formed a phylogenetically branch distinct from those of previously sequenced HHV8 strains and shared specific mutations in 9 proteins. These mutations were verified in Okinawan patients other than those from Miyako Islands. Whole-exome sequencing of the 4 male Miyako Islanders did not reveal shared pathogenic mutations. Conclusions Miyako Islands are an endemic area of non-AIDS KS. The high rate of a distinct HHV8 may contribute to the high incidence of KS in the region.
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Affiliation(s)
- Ryoko Awazawa
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Daisuke Utsumi
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Harutaka Katano
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tsuyoshi Awazawa
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Takuya Miyagi
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Kentaro Hayashi
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Shigetaka Matori
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Hiroshi Uezato
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
| | - Kenzo Takahashi
- Department of Dermatology, University of the Ryukyus, Graduate School of Medicine, Okinawa, Japan
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The regulatory role of protein phosphorylation in human gammaherpesvirus associated cancers. Virol Sin 2017; 32:357-368. [PMID: 29116588 PMCID: PMC6704201 DOI: 10.1007/s12250-017-4081-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/23/2017] [Indexed: 12/12/2022] Open
Abstract
Activation of specific sets of protein kinases by intracellular signal molecules
has become more and more apparent in the past decade. Phosphorylation, one of key
posttranslational modification events, is activated by kinase or regulatory protein
and is vital for controlling many physiological functions of eukaryotic cells such
as cell proliferation, differentiation, malignant transformation, and signal
transduction mediated by external stimuli. Moreovers, the reversible modification of
phosphorylation and dephosphorylation can result in different features of the target
substrate molecules including DNA binding, protein-protein interaction, subcellular
location and enzymatic activity, and is often hijacked by viral infection.
Epstein-Barr virus (EBV) and Kaposi’s sarcomaassociated herpesvirus (KSHV), two
human oncogenic gamma-herpesviruses, are shown to tightly associate with many
malignancies. In this review, we summarize the recent progresses on understanding of
molecular properties and regulatory modes of cellular and viral proteins
phosphorylation influenced by these two tumor viruses, and highlight the potential
therapeutic targets and strategies against their related cancers. ![]()
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16
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Koch S, Schulz TF. Rhadinoviral interferon regulatory factor homologues. Biol Chem 2017; 398:857-870. [PMID: 28455950 DOI: 10.1515/hsz-2017-0111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/20/2017] [Indexed: 01/17/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8 (HHV8) is a gammaherpesvirus and the etiological agent of Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman disease. The KSHV genome contains genes for a unique group of proteins with homology to cellular interferon regulatory factors, termed viral interferon regulatory factors (vIRFs). This review will give an overview over the oncogenic, antiapoptotic and immunomodulatory characteristics of KSHV and related vIRFs.
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KSHV-encoded viral interferon regulatory factor 4 (vIRF4) interacts with IRF7 and inhibits interferon alpha production. Biochem Biophys Res Commun 2017; 486:700-705. [PMID: 28342865 DOI: 10.1016/j.bbrc.2017.03.101] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 03/21/2017] [Indexed: 01/26/2023]
Abstract
Before an infection can be completely established, the host immediately turns on the innate immune system through activating the interferon (IFN)-mediated antiviral pathway. Kaposi's sarcoma-associated herpesvirus (KSHV) utilizes a unique antagonistic mechanism of type I IFN-mediated host antiviral immunity by incorporating four viral interferon regulatory factors (vIRF1-4). Herein, we characterized novel immune evasion strategies of vIRF4 to inhibit the IRF7-mediated IFN-α production. KSHV vIRF4 specifically interacts with IRF7, resulting in inhibition of IRF7 dimerization and ultimately suppresses IRF7-mediated activation of type I IFN. These results suggest that each of the KSHV vIRFs, including vIRF4, subvert IFN-mediated anti-viral response via different mechanisms. Therefore, it is indicated that KSHV vIRFs are indeed a crucial immunomodulatory component of their life cycles.
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Narkwa PW, Blackbourn DJ, Mutocheluh M. Aflatoxin B 1 inhibits the type 1 interferon response pathway via STAT1 suggesting another mechanism of hepatocellular carcinoma. Infect Agent Cancer 2017; 12:17. [PMID: 28344639 PMCID: PMC5360051 DOI: 10.1186/s13027-017-0127-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/10/2017] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Aflatoxin B1 (AFB1) contamination of food is very high in most sub-Saharan African countries. AFB1 is known to cause hepatocellular carcinoma (HCC) by inducing mutation in the tumour suppressor gene TP53. The number of new HCC cases is high in West Africa with an accompanying high mortality. The type I interferon (IFN) pathway of the innate immune system limits viral infections and exerts its anti-cancer property by up-regulating tumour suppressor activities and pro-apoptotic pathways. Indeed, IFN-α is reported to show significant protective effects against hepatic fibrogenesis and carcinogenesis. However, the mechanism behind AFB1 deregulation of the type I interferon (IFN) signalling pathway, with consequent HCC is largely unknown. This current study seeks to test the hypothesis that AFB1 inhibits the type I IFN response by directly interfering with key signalling proteins and thus increase the risk of HCC in humans. METHODS We evaluated the effects of AFB1 on the type I IFN signalling pathway using IFN stimulated response element (ISRE)-based luciferase reporter gene assay. In addition, the effects of AFB1 on the transcript levels of JAK1, STAT1 and OAS3 were assessed by real-time quantitative polymerase chain reaction (RT-qPCR) and confirmed by immunoblot assay. RESULTS Our results indicated that AFB1 inhibited the type I IFN signalling pathway in human hepatoma cell line HepG2 cells by suppressing the transcript levels of JAK1, STAT1 and OAS3. AFB1 also decreased the accumulation of STAT1 protein. CONCLUSION The inhibition of the type I IFN anti-cancer response pathway by AFB1 suggest a novel mechanism by which AFB1 may induce hepatocellular carcinoma in humans.
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Affiliation(s)
- Patrick W. Narkwa
- Department of Clinical Microbiology, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - David J. Blackbourn
- Department of Microbial and Cellular Sciences, School of Biosciences and Medicine, University of Surrey, Surrey, GU2 7XH UK
| | - Mohamed Mutocheluh
- Department of Clinical Microbiology, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
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Gao H, Song Y, Liu C, Liang Q. KSHV strategies for host dsDNA sensing machinery. Virol Sin 2016; 31:466-471. [PMID: 27933565 DOI: 10.1007/s12250-016-3877-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/21/2016] [Indexed: 12/21/2022] Open
Abstract
The innate immune system utilizes pattern recognition receptors cyclic GMP-AMP synthase (cGAS) to sense cytosolic double-stranded (ds) DNA and initiate type 1 interferon signaling and autophagy pathway, which collaborate to limit pathogen infections as well as alarm the adaptive immune response. The genomes of herpesviruses are large dsDNA, which represent a major class of pathogen signatures recognized by cellular DNA sensor cGAS. However, to successfully establish the persistent infection, herpesviruses have evolved their viral genes to modulate different aspects of host immune signaling. This review summarizes the evasion strategies of host cGAS DNA sensing pathway by Kaposi's Sarcoma-associated Herpesvirus (KSHV) and their contributions to KSHV life cycles.
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Affiliation(s)
- Hang Gao
- Department of Bone and Joint Surgery, The First Hospital of Jilin University, Changchun, 130021, China
| | - Yanyan Song
- Department of Nephrology, The Second Hospital of Jilin University, Changchun, 130041, China
| | - Chengrong Liu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Qiming Liang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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20
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Crow MS, Lum KK, Sheng X, Song B, Cristea IM. Diverse mechanisms evolved by DNA viruses to inhibit early host defenses. Crit Rev Biochem Mol Biol 2016; 51:452-481. [PMID: 27650455 PMCID: PMC5285405 DOI: 10.1080/10409238.2016.1226250] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In mammalian cells, early defenses against infection by pathogens are mounted through a complex network of signaling pathways shepherded by immune-modulatory pattern-recognition receptors. As obligate parasites, the survival of viruses is dependent on the evolutionary acquisition of mechanisms that tactfully dismantle and subvert the cellular intrinsic and innate immune responses. Here, we review the diverse mechanisms by which viruses that accommodate DNA genomes are able to circumvent activation of cellular immunity. We start by discussing viral manipulation of host defense protein levels by either transcriptional regulation or protein degradation. We next review viral strategies used to repurpose or inhibit these cellular immune factors by molecular hijacking or by regulating their post-translational modification status. Additionally, we explore the infection-induced temporal modulation of apoptosis to facilitate viral replication and spread. Lastly, the co-evolution of viruses with their hosts is highlighted by the acquisition of elegant mechanisms for suppressing host defenses via viral mimicry of host factors. In closing, we present a perspective on how characterizing these viral evasion tactics both broadens the understanding of virus-host interactions and reveals essential functions of the immune system at the molecular level. This knowledge is critical in understanding the sources of viral pathogenesis, as well as for the design of antiviral therapeutics and autoimmunity treatments.
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Affiliation(s)
- Marni S. Crow
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Krystal K. Lum
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Xinlei Sheng
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Bokai Song
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
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21
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Genome-Wide Mapping of the Binding Sites and Structural Analysis of Kaposi's Sarcoma-Associated Herpesvirus Viral Interferon Regulatory Factor 2 Reveal that It Is a DNA-Binding Transcription Factor. J Virol 2015; 90:1158-68. [PMID: 26537687 DOI: 10.1128/jvi.01392-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 10/14/2015] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The oncogenic herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV) is known to encode four viral interferon regulatory factors (vIRF1 to -4) to subvert the host antiviral immune response, but their detailed DNA-binding profiles as transcription factors in the host remain uncharacterized. Here, we first performed genome-wide vIRF2-binding site mapping in the human genome using chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq). vIRF2 was capable of binding to the promoter regions of 100 putative target genes. Importantly, we confirmed that vIRF2 can specifically interact with the promoters of the genes encoding PIK3C3, HMGCR, and HMGCL, which are associated with autophagosome formation or tumor progression and metastasis, and regulate their transcription in vivo. The crystal structure of the vIRF2 DNA-binding domain (DBD) (referred to here as vIRF2DBD) showed variable loop conformations and positive-charge distributions different from those of vIRF1 and cellular IRFs that are associated with DNA-binding specificities. Structure-based mutagenesis revealed that Arg82 and Arg85 are required for the in vitro DNA-binding activity of vIRF2DBD and can abolish the transcription regulation function of vIRF2 on the promoter reporter activity of PIK3C3, HMGCR, and HMGCL. Collectively, our study provided unique insights into the DNA-binding potency of vIRF2 and suggested that vIRF2 could act as a transcription factor of its target genes in the host antiviral immune response. IMPORTANCE The oncogenic herpesvirus KSHV is the etiological agent of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. KSHV has developed a unique mechanism to subvert the host antiviral immune responses by encoding four homologues of cellular interferon regulatory factors (vIRF1 to -4). However, none of their DNA-binding profiles in the human genome have been characterized until now, and the structural basis for their diverse DNA-binding properties remain poorly understood. In this study, we performed the first genome-wide vIRF2-binding site mapping in the human genome and found vIRF2 can bind to the promoter regions of 100 target cellular genes. X-ray structure analysis and functional studies provided unique insights into its DNA-binding potency and regulation of target gene expression. Our study suggested that vIRF2 could act as a transcription factor of its target genes and contribute to KSHV infection and pathogenesis through versatile functions.
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22
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Lee HR, Amatya R, Jung JU. Multi-step regulation of innate immune signaling by Kaposi's sarcoma-associated herpesvirus. Virus Res 2015; 209:39-44. [PMID: 25796211 PMCID: PMC4575611 DOI: 10.1016/j.virusres.2015.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/06/2015] [Accepted: 03/09/2015] [Indexed: 12/15/2022]
Abstract
The innate immune system provides an immediate and relatively non-specific response to infection with the aim of eliminating the pathogen before an infection can be fully established. Activation of innate immune response is achieved by production of pro-inflammatory cytokines and type I interferon (IFN). The IFN response in particular is one of the primary defenses utilized by the host innate immune system to control pathogen infection, like virus infection. Hence, viruses have learned to manipulate host immune control mechanisms to facilitate their propagation. Due to this, much work has been dedicated to the elucidation of the Kaposi's sarcoma-associated herpesvirus (KSHV)-mediated immune evasion tactics that antagonize a host's immune system. This review presents our current knowledge of the immune evasion strategies employed by KSHV at distinct stages of its life cycle to control a host's immune system with a focus on interferon signaling.
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Affiliation(s)
- Hye-Ra Lee
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Harlyne J. Norris Cancer Research Tower, 1450 Biggy Street, Los Angeles, CA 90033, USA.
| | - Rina Amatya
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Harlyne J. Norris Cancer Research Tower, 1450 Biggy Street, Los Angeles, CA 90033, USA
| | - Jae U Jung
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Harlyne J. Norris Cancer Research Tower, 1450 Biggy Street, Los Angeles, CA 90033, USA; Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, HMR Rm 401, 2011 Zonal Avenue, Los Angeles, CA 90033, USA
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Schulz TF, Cesarman E. Kaposi Sarcoma-associated Herpesvirus: mechanisms of oncogenesis. Curr Opin Virol 2015; 14:116-28. [PMID: 26431609 DOI: 10.1016/j.coviro.2015.08.016] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 08/30/2015] [Indexed: 10/23/2022]
Abstract
Kaposi Sarcoma-associated Herpesvirus (KSHV, HHV8) causes three human malignancies, Kaposi Sarcoma (KS), an endothelial tumor, as well as Primary Effusion Lymphoma (PEL) and the plasma cell variant of Multicentric Castleman's Disease (MCD), two B-cell lymphoproliferative diseases. All three cancers occur primarily in the context of immune deficiency and/or HIV infection, but their pathogenesis differs. KS most likely results from the combined effects of an endotheliotropic virus with angiogenic properties and inflammatory stimuli and thus represents an interesting example of a cancer that arises in an inflammatory context. Viral and cellular angiogenic and inflammatory factors also play an important role in the pathogenesis of MCD. In contrast, PEL represents an autonomously growing malignancy that is, however, still dependent on the continuous presence of KSHV and the action of several KSHV proteins.
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Affiliation(s)
- Thomas F Schulz
- Institute of Virology, Hannover Medical School, Hannover, Germany; German Centre of Infection Research, Hannover-Braunschweig Site, Hannover, Germany.
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, USA.
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Varicella Viruses Inhibit Interferon-Stimulated JAK-STAT Signaling through Multiple Mechanisms. PLoS Pathog 2015; 11:e1004901. [PMID: 25973608 PMCID: PMC4431795 DOI: 10.1371/journal.ppat.1004901] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 04/21/2015] [Indexed: 12/17/2022] Open
Abstract
Varicella zoster virus (VZV) causes chickenpox in humans and, subsequently, establishes latency in the sensory ganglia from where it reactivates to cause herpes zoster. Infection of rhesus macaques with simian varicella virus (SVV) recapitulates VZV pathogenesis in humans thus representing a suitable animal model for VZV infection. While the type I interferon (IFN) response has been shown to affect VZV replication, the virus employs counter mechanisms to prevent the induction of anti-viral IFN stimulated genes (ISG). Here, we demonstrate that SVV inhibits type I IFN-activated signal transduction via the JAK-STAT pathway. SVV-infected rhesus fibroblasts were refractory to IFN stimulation displaying reduced protein levels of IRF9 and lacking STAT2 phosphorylation. Since previous work implicated involvement of the VZV immediate early gene product ORF63 in preventing ISG-induction we studied the role of SVV ORF63 in generating resistance to IFN treatment. Interestingly, SVV ORF63 did not affect STAT2 phosphorylation but caused IRF9 degradation in a proteasome-dependent manner, suggesting that SVV employs multiple mechanisms to counteract the effect of IFN. Control of SVV ORF63 protein levels via fusion to a dihydrofolate reductase (DHFR)-degradation domain additionally confirmed its requirement for viral replication. Our results also show a prominent reduction of IRF9 and inhibition of STAT2 phosphorylation in VZV-infected cells. In addition, cells expressing VZV ORF63 blocked IFN-stimulation and displayed reduced levels of the IRF9 protein. Taken together, our data suggest that varicella ORF63 prevents ISG-induction both directly via IRF9 degradation and indirectly via transcriptional control of viral proteins that interfere with STAT2 phosphorylation. SVV and VZV thus encode multiple viral gene products that tightly control IFN-induced anti-viral responses. In this manuscript we demonstrate that the immediate early protein ORF63 encoded by varicella zoster virus (VZV) and simian varicella virus (SVV) interferes with interferon type I-mediated activation of JAK-STAT signaling and thereby inhibits the expression of interferon stimulated genes. ORF63 blocks this pathway by degrading IRF9, which plays a central role in JAK-STAT signaling. In addition, both viruses code for immune evasion mechanisms affecting the JAK-STAT pathway upstream of IRF9, which results in the inhibition of STAT2 phosphorylation. By fusing a degradation domain derived from dihydrofolate reductase (DHFR) to ORF63 we further demonstrate that this protein is essential for SVV growth and gene expression, indicating that ORF63 also affects IFN-signaling indirectly by regulating the expression of other immune evasion genes.
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25
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A Rhesus Rhadinovirus Viral Interferon (IFN) Regulatory Factor Is Virion Associated and Inhibits the Early IFN Antiviral Response. J Virol 2015; 89:7707-21. [PMID: 25972548 DOI: 10.1128/jvi.01175-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 05/08/2015] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED The interferon (IFN) response is the earliest host immune response dedicated to combating viral infection. As such, viruses have evolved strategies to subvert this potent antiviral response. Two closely related gammaherpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV) and rhesus macaque rhadinovirus (RRV), are unique in that they express viral homologues to cellular interferon regulatory factors (IRFs), termed viral IRFs (vIRFs). Cellular IRFs are a family of transcription factors that are particularly important for the transcription of type I IFNs. Here, we demonstrate a strategy employed by RRV to ensure rapid inhibition of virus-induced type I IFN induction. We found that RRV vIRF R6, when expressed ectopically, interacts with a transcriptional coactivator, CREB-binding protein (CBP), in the nucleus. As a result, phosphorylated IRF3, an important transcriptional regulator in beta interferon (IFN-β) transcription, fails to effectively bind to the IFN-β promoter, thus inhibiting the activation of IFN-β genes. In addition, we found R6 within RRV virion particles via immunoelectron microscopy and, furthermore, that virion-associated R6 is capable of inhibiting the type I IFN response by preventing efficient binding of IRF3/CBP complexes to the IFN-β promoter in the context of infection. The work shown here is the first example of a vIRF being associated with either the KSHV or RRV virion. The presence of this immunomodulatory protein in the RRV virion provides the virus with an immediate mechanism to evade the host IFN response, thus enabling the virus to effectively establish an infection within the host. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) and the closely related rhesus macaque rhadinovirus (RRV) are the only viruses known to encode viral homologues to cellular interferon regulatory factors (IRFs), known as vIRFs. In KSHV, these proteins have been shown to play major roles in a variety of cellular processes and are particularly important in the evasion of the host type I interferon (IFN) response. In this study, we delineate the immunomodulatory mechanism of an RRV vIRF and its ability to assist the virus in rapid immune evasion by being prepackaged within the virion, thus providing evidence, for the first time, of a virion-associated vIRF. This work further contributes to our understanding of the mechanisms behind immunomodulation by the RRV vIRFs during infection.
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Abstract
ABSTRACT Viruses have evolved to subvert host cell pathways to enable their replication and persistence. In particular, virus-encoded gene products target the host's immune system to evade elimination by antiviral immune defenses. Cytokines are soluble, secreted proteins, which regulate many aspects of immune responses, by providing signals through cell surface receptors on target cells. Cytokine pathways are therefore attractive targets for modulation by viruses during their replication cycle. This review deals with modulation of cytokine pathways by the human herpesvirus, a family of viruses that are capable of life-long persistence in the host and cause severe disease particularly in immunocompromised individuals.
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Distinct roles of Kaposi's sarcoma-associated herpesvirus-encoded viral interferon regulatory factors in inflammatory response and cancer. J Virol 2013; 87:9398-410. [PMID: 23785197 DOI: 10.1128/jvi.03315-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent associated with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). Similar to other herpesviruses, KSHV has two life cycles, latency and lytic replication. In latency, the KSHV genome persists as a circular episome in the nucleus of the host cell and only a few viral genes are expressed. In this review, we focus on oncogenic, antiapoptotic, and immunomodulating properties of KSHV-encoded homologues of cellular interferon regulatory factors (IRFs)--viral IRF1 (vIRF1) to vIRF4--and their possible role in the KSHV-mediated antiviral response, apoptosis, and oncogenicity.
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Jochmann R, Pfannstiel J, Chudasama P, Kuhn E, Konrad A, Stürzl M. O-GlcNAc transferase inhibits KSHV propagation and modifies replication relevant viral proteins as detected by systematic O-GlcNAcylation analysis. Glycobiology 2013; 23:1114-30. [PMID: 23580777 DOI: 10.1093/glycob/cwt028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
O-GlcNAcylation is an inducible, highly dynamic and reversible post-translational modification, mediated by a unique enzyme named O-linked N-acetyl-d-glucosamine (O-GlcNAc) transferase (OGT). In response to nutrients, O-GlcNAc levels are differentially regulated on many cellular proteins involved in gene expression, translation, immune reactions, protein degradation, protein-protein interaction, apoptosis and signal transduction. In contrast to eukaryotic cells, little is known about the role of O-GlcNAcylation in the viral life cycle. Here, we show that the overexpression of the OGT reduces the replication efficiency of Kaposi's sarcoma-associated herpesvirus (KSHV) in a dose-dependent manner. In order to investigate the global impact of O-GlcNAcylation in the KSHV life cycle, we systematically analyzed the 85 annotated KSHV-encoded open reading frames for O-GlcNAc modification. For this purpose, an immunoprecipitation (IP) strategy with three different approaches was carried out and the O-GlcNAc signal of the identified proteins was properly controlled for specificity. Out of the 85 KSHV-encoded proteins, 18 proteins were found to be direct targets for O-GlcNAcylation. Selected proteins were further confirmed by mass spectrometry for O-GlcNAc modification. Correlation of the functional annotation and the O-GlcNAc status of KSHV proteins showed that the predominant targets were proteins involved in viral DNA synthesis and replication. These results indicate that O-GlcNAcylation plays a major role in the regulation of KSHV propagation.
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Affiliation(s)
- Ramona Jochmann
- Division of Molecular and Experimental Surgery, University Medical Center Erlangen, Friedrich-Alexander University of Erlangen-Nuremberg, Schwabachanlage 10, 91054 Erlangen, Germany
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Taylor KE, Mossman KL. Recent advances in understanding viral evasion of type I interferon. Immunology 2013; 138:190-7. [PMID: 23173987 PMCID: PMC3573272 DOI: 10.1111/imm.12038] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 10/11/2012] [Accepted: 11/14/2012] [Indexed: 12/21/2022] Open
Abstract
The type I interferon (IFN) system mediates a wide variety of antiviral effects and represents an important first barrier to virus infection. Consequently, viruses have developed an impressive diversity of tactics to circumvent IFN responses. Evasion strategies can involve preventing initial virus detection, via the disruption of the Toll‐like receptors or the retinoic acid inducible gene I (RIG‐I) ‐like receptors, or by avoiding the initial production of the ligands recognized by these receptors. An alternative approach is to preclude IFN production by disarming or degrading the transcription factors involved in the expression of IFN, such as interferon regulatory factor 3 (IRF3)/IRF7, nuclear factor‐κB (NF‐κB), or ATF‐2/c‐jun, or by inducing a general block on host cell transcription. Viruses also oppose IFN signalling, both by disturbing the type I IFN receptor and by impeding JAK/STAT signal transduction upon IFN receptor engagement. In addition, the global expression of IFN‐stimulated genes (ISGs) can be obstructed via interference with epigenetic signalling, and specific ISGs can also be selectively targeted for inhibition. Finally, some viruses disrupt IFN responses by co‐opting negative regulatory systems, whereas others use antiviral mechanisms to their own advantage. Here, we review recent developments in this field.
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Affiliation(s)
- Kathryne E Taylor
- Department of Biochemistry and Biomedical Sciences, McMaster Immunology Research Centre, Michael DeGroote Centre for Learning and Discovery, McMaster University, Hamilton, ON, Canada
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Hew K, Dahlroth SL, Venkatachalam R, Nasertorabi F, Lim BT, Cornvik T, Nordlund P. The crystal structure of the DNA-binding domain of vIRF-1 from the oncogenic KSHV reveals a conserved fold for DNA binding and reinforces its role as a transcription factor. Nucleic Acids Res 2013; 41:4295-306. [PMID: 23435230 PMCID: PMC3627575 DOI: 10.1093/nar/gkt082] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus encodes four viral homologues to cellular interferon regulatory factors (IRFs), where the most studied is vIRF-1. Even though vIRF-1 shows sequence homology to the N-terminal DNA-binding domain (DBD) of human IRFs, a specific role for this domain in vIRF-1’s function has remained uncertain. To provide insights into the function of the vIRF-1 DBD, we have determined the crystal structure of it in complex with DNA and in its apo-form. Using a thermal stability shift assay (TSSA), we show that the vIRF-1 DBD binds DNA, whereas full-length vIRF-1 does not, suggesting a cis-acting regulatory mechanism in similarity to human IRFs. The complex structure of vIRF-1 DBD reveals interactions with the DNA backbone and the positioning of two arginines for specific recognition in the major grove. A superimposition with human IRF-3 reveals a similar positioning of the two specificity-determining arginines, and additional TSSAs indicate binding of vIRF-1 to an IRF-3 operator consensus sequence. The results from this study, therefore, provide support that vIRF-1 has evolved to bind DNA and plays a role in DNA binding in the context of transcriptional regulation and might act on some of the many operator sequences controlled by human IRF-3.
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Affiliation(s)
- Kelly Hew
- Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
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31
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Jacobs SR, Gregory SM, West JA, Wollish AC, Bennett CL, Blackbourn DJ, Heise MT, Damania B. The viral interferon regulatory factors of kaposi's sarcoma-associated herpesvirus differ in their inhibition of interferon activation mediated by toll-like receptor 3. J Virol 2013; 87:798-806. [PMID: 23115281 PMCID: PMC3554052 DOI: 10.1128/jvi.01851-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/23/2012] [Indexed: 01/11/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) infection is correlated with three human malignancies and can establish lifelong latent infection in multiple cell types within its human host. In order to establish and maintain infection, KSHV utilizes multiple mechanisms to evade the host immune response. One such mechanism is the expression of a family of genes with homology to cellular interferon (IFN) regulatory factors (IRFs), known as viral IRFs (vIRFs). We demonstrate here that KSHV vIRF1, -2, and -3 have a differential ability to block type I interferon signaling mediated by Toll-like receptor 3 (TLR3), a receptor we have previously shown to be activated upon KSHV infection. vIRF1, -2, and -3 inhibited TLR3-driven activation of IFN transcription reporters. However, only vIRF1 and vIRF2 inhibited increases in both IFN-β message and protein levels following TLR3 activation. The expression of vIRF1 and vIRF2 also allowed for increased replication of a virus known to activate TLR3 signaling. Furthermore, vIRF1 and vIRF2 may block TLR3-mediated signaling via different mechanisms. Altogether, this report indicates that vIRFs are able to block IFN mediated by TLRs but that each vIRF has a unique function and mechanism for blocking antiviral IFN responses.
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Affiliation(s)
- Sarah R. Jacobs
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Sean M. Gregory
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - John A. West
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Amy C. Wollish
- Department of Genetics and Department of Microbiology and Immunology, the Carolina Vaccine Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Christopher L. Bennett
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - David J. Blackbourn
- School of Cancer Sciences and Cancer Research United Kingdom Centre, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Mark T. Heise
- Department of Genetics and Department of Microbiology and Immunology, the Carolina Vaccine Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Blossom Damania
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Lee HR, Brulois K, Wong L, Jung JU. Modulation of Immune System by Kaposi's Sarcoma-Associated Herpesvirus: Lessons from Viral Evasion Strategies. Front Microbiol 2012; 3:44. [PMID: 22403573 PMCID: PMC3293256 DOI: 10.3389/fmicb.2012.00044] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Accepted: 01/27/2012] [Indexed: 12/14/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), a member of the herpesvirus family, has evolved to establish a long-term, latent infection of cells such that while they carry the viral genome gene expression is highly restricted. Latency is a state of cryptic viral infection associated with genomic persistence in their host and this hallmark of KSHV infection leads to several clinical-epidemiological diseases such as KS, a plasmablastic variant of multicentric Castleman's disease, and primary effusion lymphoma upon immune suppression of infected hosts. In order to sustain efficient life-long persistency as well as their life cycle, KSHV dedicates a large portion of its genome to encode immunomodulatory proteins that antagonize its host's immune system. In this review, we will describe our current knowledge of the immune evasion strategies employed by KSHV at distinct stages of its viral life cycle to control the host's immune system.
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Affiliation(s)
- Hye-Ra Lee
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
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