1
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Morales AE, Gumenick R, Genovese CM, Jang YY, Ouedraogo A, Ibáñez de Garayo M, Pannellini T, Patel S, Bott ME, Alvarez J, Mun SS, Totonchy J, Gautam A, Delgado de la Mora J, Chang S, Wirth D, Horenstein M, Dao T, Scheinberg DA, Rubinstein PG, Semeere A, Martin J, Godfrey CC, Moser CB, Matining RM, Campbell TB, Borok MZ, Krown SE, Cesarman E. Wilms' tumor 1 (WT1) antigen is overexpressed in Kaposi Sarcoma and is regulated by KSHV vFLIP. PLoS Pathog 2024; 20:e1011881. [PMID: 38190392 PMCID: PMC10898863 DOI: 10.1371/journal.ppat.1011881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 02/27/2024] [Accepted: 12/04/2023] [Indexed: 01/10/2024] Open
Abstract
In people living with HIV, Kaposi Sarcoma (KS), a vascular neoplasm caused by KS herpesvirus (KSHV/HHV-8), remains one of the most common malignancies worldwide. Individuals living with HIV, receiving otherwise effective antiretroviral therapy, may present with extensive disease requiring chemotherapy. Hence, new therapeutic approaches are needed. The Wilms' tumor 1 (WT1) protein is overexpressed and associated with poor prognosis in several hematologic and solid malignancies and has shown promise as an immunotherapeutic target. We found that WT1 was overexpressed in >90% of a total 333 KS biopsies, as determined by immunohistochemistry and image analysis. Our largest cohort from ACTG, consisting of 294 cases was further analyzed demonstrating higher WT1 expression was associated with more advanced histopathologic subtypes. There was a positive correlation between the proportion of infected cells within KS tissues, assessed by expression of the KSHV-encoded latency-associated nuclear antigen (LANA), and WT1 positivity. Areas with high WT1 expression showed sparse T-cell infiltrates, consistent with an immune evasive tumor microenvironment. We show that major oncogenic isoforms of WT1 are overexpressed in primary KS tissue and observed WT1 upregulation upon de novo infection of endothelial cells with KSHV. KSHV latent viral FLICE-inhibitory protein (vFLIP) upregulated total and major isoforms of WT1, but upregulation was not seen after expression of mutant vFLIP that is unable to bind IKKƴ and induce NFκB. siRNA targeting of WT1 in latent KSHV infection resulted in decreased total cell number and pAKT, BCL2 and LANA protein expression. Finally, we show that ESK-1, a T cell receptor-like monoclonal antibody that recognizes WT1 peptides presented on MHC HLA-A0201, demonstrates increased binding to endothelial cells after KSHV infection or induction of vFLIP expression. We propose that oncogenic isoforms of WT1 are upregulated by KSHV to promote tumorigenesis and immunotherapy directed against WT1 may be an approach for KS treatment.
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Affiliation(s)
- Ayana E. Morales
- Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Ruby Gumenick
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Caitlyn M. Genovese
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Yun Yeong Jang
- Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Ariene Ouedraogo
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Maite Ibáñez de Garayo
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Tania Pannellini
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Sanjay Patel
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Matthew E. Bott
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Julio Alvarez
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Sung Soo Mun
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Jennifer Totonchy
- School of Pharmacy, Chapman University, Irvine, California, United States of America
| | - Archana Gautam
- Department of Allergy and Immunology, Icahn School of Medicine, New York, New York, United States of America
| | - Jesus Delgado de la Mora
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Stephanie Chang
- Cornell University, Ithaca, New York, United States of America
| | - Dagmar Wirth
- Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Marcelo Horenstein
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Tao Dao
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - David A. Scheinberg
- Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Paul G. Rubinstein
- Section of Hematology/Oncology, John H. Stroger Jr Hospital of Cook County (Cook County Hospital), Ruth M. Rothstein Core Center, University of Illinois, Chicago, Illinois, United States of America
| | - Aggrey Semeere
- Infectious Diseases Institute, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Jeffrey Martin
- Department of Epidemiology and Biostatistics, University of California, San Francisco, California, United States of America
| | - Catherine C. Godfrey
- Office of the Global AIDS Coordinator, Department of State, Washington, DC, United States of America
| | - Carlee B. Moser
- Center for Biostatistics in AIDS Research, Harvard T H Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Roy M. Matining
- Center for Biostatistics in AIDS Research, Harvard T H Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Thomas B. Campbell
- Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Margaret Z. Borok
- Department of Internal Medicine, University of Zimbabwe, Harare, Zimbabwe
| | - Susan E. Krown
- Memorial Sloan Kettering Cancer Center (emerita), New York, New York, United States of America
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, United States of America
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2
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Fang Y, Peng K. Regulation of innate immune responses by cell death-associated caspases during virus infection. FEBS J 2021; 289:4098-4111. [PMID: 34089572 DOI: 10.1111/febs.16051] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/04/2021] [Accepted: 06/03/2021] [Indexed: 01/04/2023]
Abstract
Viruses are obligate intracellular pathogens that rely on cellular machinery for successful replication and dissemination. The host cells encode a number of different strategies to sense and restrict the invading viral pathogens. Caspase-mediated programmed cell death pathways that are triggered by virus infection, such as apoptosis and pyroptosis, provide a means for the infected cells to limit viral proliferation, leading to suicidal cell death (apoptosis) or lytic cell death and alerting uninfected cells to mount anti-viral responses (pyroptosis). However, some viruses can employ activated caspases to dampen the anti-viral responses and facilitate viral replication through cleavage of critical molecules of the innate immune pathways. The regulation of innate immune responses by caspase activation during virus infection has recently become an important topic. In this review, we briefly introduce the characteristics of different classes of caspases and the cell death pathways regulated by these caspases. We then describe how viruses trigger or dampen caspase activation during infection and how these activated caspases regulate three major innate immune response pathways of viral infections: the retinoic acid-inducible gene I-like receptor, toll-like receptor and cyclic GMP-AMP synthase-stimulator of interferon genes pathways.
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Affiliation(s)
- Yujie Fang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ke Peng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
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3
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Bais SS, Ratra Y, Khan NA, Pandey R, Kushawaha PK, Tomar S, Medigeshi G, Singh A, Basak S. Chandipura Virus Utilizes the Prosurvival Function of RelA NF-κB for Its Propagation. J Virol 2019; 93:e00081-19. [PMID: 31043529 PMCID: PMC6600208 DOI: 10.1128/jvi.00081-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/23/2019] [Indexed: 11/20/2022] Open
Abstract
Chandipura virus (CHPV), a cytoplasmic RNA virus, has been implicated in several outbreaks of acute encephalitis in India. Despite the relevance of CHPV to human health, how the virus interacts with the host signaling machinery remains obscure. In response to viral infections, mammalian cells activate RelA/NF-κB heterodimers, which induce genes encoding interferon beta (IFN-β) and other immune mediators. Therefore, RelA is generally considered to be an antiviral transcription factor. However, RelA activates a wide spectrum of genes in physiological settings, and there is a paucity of direct genetic evidence substantiating antiviral RelA functions. Using mouse embryonic fibroblasts, we genetically dissected the role of RelA in CHPV pathogenesis. We found that CHPV indeed activated RelA and that RelA deficiency abrogated the expression of IFN-β in response to virus infections. Unexpectedly, infection of Rela-/- fibroblasts led to a decreased CHPV yield. Our investigation clarified that RelA-dependent synthesis of prosurvival factors restrained infection-inflicted cell death and that exacerbated cell death processes prevented multiplication of CHPV in RelA-deficient cells. Chikungunya virus, a cytopathic RNA virus associated also with epidemics, required RelA, and Japanese encephalitis virus, which produced relatively minor cytopathic effects in fibroblasts, circumvented the need of RelA for their propagation. In sum, we documented a proviral function of the pleiotropic factor RelA linked to its prosurvival properties. RelA promoted the growth of cytopathic RNA viruses by extending the life span of infected cells, which serve as the replicative niche of intracellular pathogens. We argue that our finding bears significance for understanding host-virus interactions and may have implications for antiviral therapeutic regimes.IMPORTANCE RelA/NF-κB participates in a wide spectrum of physiological processes, including shaping immune responses against invading pathogens. In virus-infected cells, RelA typically induces the expression of IFN-β, which restrains viral propagation in neighboring cells involving paracrine mechanisms. Our study suggested that RelA might also play a proviral role. A cell-autonomous RelA activity amplified the yield of Chandipura virus, a cytopathic RNA virus associated with human epidemics, by extending the life span of infected cells. Our finding necessitates a substantial revision of our understanding of host-virus interactions and indicates a dual role of NF-κB signaling during the course of RNA virus infections. Our study also bears significance for therapeutic regimes which alter NF-κB activities while alleviating the viral load.
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Affiliation(s)
- Sachendra S Bais
- Systems Immunology Laboratory, National Institute of Immunology, New Delhi, India
| | - Yashika Ratra
- Systems Immunology Laboratory, National Institute of Immunology, New Delhi, India
| | - Naseem A Khan
- Translational Health Sciences and Technology Institute, Faridabad, India
| | - Rakesh Pandey
- Systems Immunology Laboratory, National Institute of Immunology, New Delhi, India
| | - Pramod K Kushawaha
- Systems Immunology Laboratory, National Institute of Immunology, New Delhi, India
| | - Shailly Tomar
- Department of Biotechnology, Indian Institute of Technology, Roorkee, India
| | | | - Abhyudai Singh
- Biomedical Engineering Department, University of Delaware, Newark, New Jersey, USA
| | - Soumen Basak
- Systems Immunology Laboratory, National Institute of Immunology, New Delhi, India
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Abstract
Immunosuppression is essential to prevent graft rejection. However, immunosuppression impairs the ability of the host immune system to control viral infection and decreases tumor immunosurveillance. Therefore, immunosuppression after organ transplantation is a major risk factor for posttransplantation cancer. Notably, recent reports suggest that immunosuppressive agents can activate tumorigenic pathways independent of the involvement of the host immune system. In this review, we focus on cell-intrinsic tumorigenic pathways directly activated by immunosuppressive agents and discuss the much-described infection- and immune-mediated mechanisms of cancer development in organ transplant recipients.
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Affiliation(s)
- Murugabaskar Balan
- Division of Nephrology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Samik Chakraborty
- Division of Nephrology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Soumitro Pal
- Division of Nephrology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
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5
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Ruder B, Murtadak V, Stürzl M, Wirtz S, Distler U, Tenzer S, Mahapatro M, Greten FR, Hu Y, Neurath MF, Cesarman E, Ballon G, Günther C, Becker C. Chronic intestinal inflammation in mice expressing viral Flip in epithelial cells. Mucosal Immunol 2018; 11:1621-1629. [PMID: 30104627 PMCID: PMC8063487 DOI: 10.1038/s41385-018-0068-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 07/04/2018] [Accepted: 07/10/2018] [Indexed: 02/04/2023]
Abstract
Viruses are present in the intestinal microflora and are currently discussed as a potential causative mechanism for the development of inflammatory bowel disease. A number of viruses, such as Human Herpesvirus-8, express homologs to cellular FLIPs, which are major contributors for the regulation of epithelial cell death. In this study we analyzed the consequences of constitutive expression of HHV8-viral FLIP in intestinal epithelial cells (IECs) in mice. Surprisingly, expression of vFlip disrupts tissue homeostasis and induces severe intestinal inflammation. Moreover vFlipIEC-tg mice showed reduced Paneth cell numbers, associated with excessive necrotic cell death. On a molecular level vFlip expression altered classical and alternative NFκB activation. Blocking of alternative NFκB signaling by deletion of Ikka in vivo largely protected mice from inflammation and Paneth cell loss induced by vFLIP. Collectively, our data provide functional evidence that expression of a single viral protein in IECs can be sufficient to disrupt epithelial homeostasis and to initiate chronic intestinal inflammation.
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Affiliation(s)
- Barbara Ruder
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Vinay Murtadak
- Division of Molecular and Experimental Surgery, Department of Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Michael Stürzl
- Division of Molecular and Experimental Surgery, Department of Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Stefan Wirtz
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Ute Distler
- Institute for Immunology, University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Stefan Tenzer
- Institute for Immunology, University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Mousumi Mahapatro
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Florian R. Greten
- Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt am Main, Germany
| | - Yinling Hu
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Markus F. Neurath
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY, USA
| | - Gianna Ballon
- Department of Pathology and Laboratory Medicine, Northwell Health, Lake Success, NY, USA
| | - Claudia Günther
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Christoph Becker
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
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6
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Mariggiò G, Koch S, Zhang G, Weidner-Glunde M, Rückert J, Kati S, Santag S, Schulz TF. Kaposi Sarcoma Herpesvirus (KSHV) Latency-Associated Nuclear Antigen (LANA) recruits components of the MRN (Mre11-Rad50-NBS1) repair complex to modulate an innate immune signaling pathway and viral latency. PLoS Pathog 2017; 13:e1006335. [PMID: 28430817 PMCID: PMC5415203 DOI: 10.1371/journal.ppat.1006335] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 05/03/2017] [Accepted: 04/05/2017] [Indexed: 12/31/2022] Open
Abstract
Kaposi Sarcoma Herpesvirus (KSHV), a γ2-herpesvirus and class 1 carcinogen, is responsible for at least three human malignancies: Kaposi Sarcoma (KS), Primary Effusion Lymphoma (PEL) and Multicentric Castleman's Disease (MCD). Its major nuclear latency protein, LANA, is indispensable for the maintenance and replication of latent viral DNA in infected cells. Although LANA is mainly a nuclear protein, cytoplasmic isoforms of LANA exist and can act as antagonists of the cytoplasmic DNA sensor, cGAS. Here, we show that cytosolic LANA also recruits members of the MRN (Mre11-Rad50-NBS1) repair complex in the cytosol and thereby inhibits their recently reported role in the sensing of cytoplasmic DNA and activation of the NF-κB pathway. Inhibition of NF-κB activation by cytoplasmic LANA is accompanied by increased lytic replication in KSHV-infected cells, suggesting that MRN-dependent NF-κB activation contributes to KSHV latency. Cytoplasmic LANA may therefore support the activation of KSHV lytic replication in part by counteracting the activation of NF-κB in response to cytoplasmic DNA. This would complement the recently described role of cytoplasmic LANA in blocking an interferon response triggered by cGAS and thereby promoting lytic reactivation. Our findings highlight a second point at which cytoplasmic LANA interferes with the innate immune response, as well as the importance of the recently discovered role of cytoplasmic MRN complex members as innate sensors of cytoplasmic DNA for the control of KSHV replication.
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MESH Headings
- Acid Anhydride Hydrolases
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Antigens, Viral/metabolism
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cytoplasm/metabolism
- DNA Repair Enzymes/genetics
- DNA Repair Enzymes/metabolism
- DNA Replication
- DNA, Viral/genetics
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- HEK293 Cells
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/immunology
- Herpesvirus 8, Human/physiology
- Humans
- Immunity, Innate
- MRE11 Homologue Protein
- Models, Biological
- NF-kappa B/genetics
- NF-kappa B/metabolism
- Nuclear Proteins/genetics
- Nuclear Proteins/immunology
- Nuclear Proteins/metabolism
- Protein Isoforms
- Sarcoma, Kaposi/immunology
- Sarcoma, Kaposi/virology
- Signal Transduction
- Virus Latency
- Virus Replication
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Affiliation(s)
- Giuseppe Mariggiò
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Sandra Koch
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Guigen Zhang
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Magdalena Weidner-Glunde
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Jessica Rückert
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Semra Kati
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Susann Santag
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Thomas F. Schulz
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
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Resveratrol induces cell death and inhibits human herpesvirus 8 replication in primary effusion lymphoma cells. Chem Biol Interact 2015; 242:372-9. [PMID: 26549478 DOI: 10.1016/j.cbi.2015.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 09/18/2015] [Accepted: 10/31/2015] [Indexed: 11/23/2022]
Abstract
Resveratrol (3,4',5-trihydroxy-trans-stilbene) has been reported to inhibit proliferation of various cancer cells. However, the effects of resveratrol on the human herpesvirus 8 (HHV8) harboring primary effusion lymphoma (PEL) cells remains unclear. The anti-proliferation effects and possible mechanisms of resveratrol in the HHV8 harboring PEL cells were examined in this study. Results showed that resveratrol induced caspase-3 activation and the formation of acidic vacuoles in the HHV8 harboring PEL cells, indicating resveratrol treatment could cause apoptosis and autophagy in PEL cells. In addition, resveratrol treatment increased ROS generation but did not lead to HHV8 reactivation. ROS scavenger (N-acetyl cysteine, NAC) could attenuate both the resveratrol induced caspase-3 activity and the formation of acidic vacuoles, but failed to attenuate resveratrol induced PEL cell death. Caspase inhibitor, autophagy inhibitors and necroptosis inhibitor could not block resveratrol induced PEL cell death. Moreover, resveratrol disrupted HHV8 latent infection, inhibited HHV8 lytic gene expression and decreased virus progeny production. Overexpression of HHV8-encoded viral FLICE inhibitory protein (vFLIP) could partially block resveratrol induced cell death in PEL cells. These data suggest that resveratrol-induced cell death in PEL cells may be mediated by disruption of HHV8 replication. Resveratrol may be a potential anti-HHV8 drug and an effective treatment for HHV8-related tumors.
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8
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Murtadak V, Becker C, Stürzl M. Cell death inhibition by KSHV. Aging (Albany NY) 2015; 7:750-1. [PMID: 26525482 PMCID: PMC4637202 DOI: 10.18632/aging.100829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/21/2015] [Indexed: 05/07/2023]
Affiliation(s)
- Vinay Murtadak
- Division of Molecular and Experimental Surgery, Translational Research Center Erlangen, Department of Surgery, 91054 Erlangen, Germany
| | - Christoph Becker
- Department of Medicine 1, Kußmaul-Campus für medizinische Forschung, Universitätsklinikum Erlangen, 91054 Erlangen, Germany
| | - Michael Stürzl
- Division of Molecular and Experimental Surgery, Translational Research Center Erlangen, Department of Surgery, 91054 Erlangen, Germany
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Identification of Caspase Cleavage Sites in KSHV Latency-Associated Nuclear Antigen and Their Effects on Caspase-Related Host Defense Responses. PLoS Pathog 2015. [PMID: 26218605 PMCID: PMC4517896 DOI: 10.1371/journal.ppat.1005064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, is the causative agent of three hyperproliferative disorders: Kaposi’s sarcoma, primary effusion lymphoma (PEL) and multicentric Castleman’s disease. During viral latency a small subset of viral genes are produced, including KSHV latency-associated nuclear antigen (LANA), which help the virus thwart cellular defense responses. We found that exposure of KSHV-infected cells to oxidative stress, or other inducers of apoptosis and caspase activation, led to processing of LANA and that this processing could be inhibited with the pan-caspase inhibitor Z-VAD-FMK. Using sequence, peptide, and mutational analysis, two caspase cleavage sites within LANA were identified: a site for caspase-3 type caspases at the N-terminus and a site for caspase-1 and-3 type caspases at the C-terminus. Using LANA expression plasmids, we demonstrated that mutation of these cleavage sites prevents caspase-1 and caspase-3 processing of LANA. This indicates that these are the principal sites that are susceptible to caspase cleavage. Using peptides spanning the identified LANA cleavage sites, we show that caspase activity can be inhibited in vitro and that a cell-permeable peptide spanning the C-terminal cleavage site could inhibit cleavage of poly (ADP-ribose) polymerase and increase viability in cells undergoing etoposide-induced apoptosis. The C-terminal peptide of LANA also inhibited interleukin-1beta (IL-1β) production from lipopolysaccharide-treated THP-1 cells by more than 50%. Furthermore, mutation of the two cleavage sites in LANA led to a significant increase in IL-1β production in transfected THP-1 cells; this provides evidence that these sites function to blunt the inflammasome, which is known to be activated in latently infected PEL cells. These results suggest that specific caspase cleavage sites in KSHV LANA function to blunt apoptosis as well as interfere with the caspase-1-mediated inflammasome, thus thwarting key cellular defense mechanisms. Upon infecting a target cell, viruses must be able to overcome cellular defense responses to survive. Two of the most important cellular defense responses against viruses are apoptosis and the inflammasome, a component of the innate immune response. Apoptosis, a programmed cell death, functions to limit the spread of viruses by destroying the infected cell while innate immune responses control viral infections through other means. Both apoptosis and the inflammasome are mediated by caspases. However, many viruses are known to encode proteins that block, suppress or delay caspase activity following cellular infection in order to block cell death and interfere with the inflammasome. We show that LANA undergoes caspase-dependent cleavage in Kaposi’s sarcoma associated herpesvirus (KSHV)-infected cells, especially when exposed to oxidative stress. Through peptide, sequence and mutational analysis, we identified two sites for caspase cleavage in KSHV LANA, one in the N-terminal region and the other in the C-terminal region. Using synthetic peptides of these cleavage sites, we show that the C-terminal site can inhibit cleavage of poly (ADP-ribose) polymerase and enhance cellular survival. Furthermore, we demonstrate that this synthetic peptide inhibits the inflammasome response as evidenced by decreased interleukin-1beta (IL-1β) production. Mutation of these cleavage sites in LANA leads to a significant increase in the inflammasome response indicated by increased IL-1β production compared to wild-type LANA. Taken in total, these results provide evidence that these cleavage sites in LANA participate both in delaying apoptosis and blunting aspects of the innate immune response. These studies provide new insights into the mechanisms by which KSHV obviates the cellular defense responses that are activated following virus infection.
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Abstract
Molluscum contagiosum virus (MCV) is the causative agent of molluscum contagiosum (MC), the third most common viral skin infection in children, and one of the five most prevalent skin diseases worldwide. No FDA-approved treatments, vaccines, or commercially available rapid diagnostics for MCV are available. This review discusses several aspects of this medically important virus including: physical properties of MCV, MCV pathogenesis, MCV replication, and immune responses to MCV infection. Sequencing of the MCV genome revealed novel immune evasion molecules which are highlighted here. Special attention is given to the MCV MC159 and MC160 proteins. These proteins are FLIPs with homologs in gamma herpesviruses and in the cell. They are of great interest because each protein regulates apoptosis, NF-κB, and IRF3. However, the mechanism that each protein uses to impart its effects is different. It is important to elucidate how MCV inhibits immune responses; this knowledge contributes to our understanding of viral pathogenesis and also provides new insights into how the immune system neutralizes virus infections.
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11
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Kaposi's sarcoma-associated herpesvirus induces Nrf2 activation in latently infected endothelial cells through SQSTM1 phosphorylation and interaction with polyubiquitinated Keap1. J Virol 2014; 89:2268-86. [PMID: 25505069 DOI: 10.1128/jvi.02742-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Nuclear factor erythroid 2-related factor 2 (Nrf2), the cellular master regulator of the antioxidant response, dissociates from its inhibitor Keap1 when activated by stress signals and participates in the pathogenesis of viral infections and tumorigenesis. Early during de novo infection of endothelial cells, KSHV induces Nrf2 through an intricate mechanism involving reactive oxygen species (ROS) and prostaglandin E2 (PGE2). When we investigated the Nrf2 activity during latent KSHV infection, we observed increased nuclear serine-40-phosphorylated Nrf2 in human KS lesions compared to that in healthy tissues. Using KSHV long-term-infected endothelial cells (LTC) as a cellular model for KS, we demonstrated that KSHV infection induces Nrf2 constitutively by extending its half-life, increasing its phosphorylation by protein kinase Cζ (PKCζ) via the infection-induced cyclooxygenase-2 (COX-2)/PGE2 axis and inducing its nuclear localization. Nrf2 knockdown in LTC decreased expression of antioxidant genes and genes involved in KS pathogenesis such as the NAD(P)H quinone oxidase 1 (NQO1), gamma glutamylcysteine synthase heavy unit (γGCSH), the cysteine transporter (xCT), interleukin 6 (IL-6), and vascular endothelial growth factor A (VEGF-A) genes. Nrf2 activation was independent of oxidative stress but dependent on the autophagic protein sequestosome-1 (SQSTM1; p62). SQSTM1 levels were elevated in LTC, a consequence of protein accumulation due to decreased autophagy and Nrf2-mediated transcriptional activation. SQSTM1 was phosphorylated on serine-351 and -403, while Keap1 was polyubiquitinated with lysine-63-ubiquitin chains, modifications known to increase their mutual affinity and interaction, leading to Keap1 degradation and Nrf2 activation. The latent KSHV protein Fas-associated death domain-like interleukin-1β-converting enzyme-inhibitory protein (vFLIP) increased SQSTM1 expression and activated Nrf2. Collectively, these results demonstrate that KSHV induces SQSTM1 to constitutively activate Nrf2, which is involved in the regulation of genes participating in KSHV oncogenesis. IMPORTANCE The transcription factor Nrf2 is activated by stress signals, including viral infection, and responds by activating the transcription of cytoprotective genes. Recently, Nrf2 has been implicated in oncogenesis and was shown to be activated during de novo KSHV infection of endothelial cells through ROS-dependent pathways. The present study was undertaken to determine the mechanism of Nrf2 activation during prolonged latent infection of endothelial cells, using an endothelial cell line latently infected with KSHV. We show that Nrf2 activation was elevated in KSHV latently infected endothelial cells independently of oxidative stress but dependent on the autophagic protein sequestosome-1 (SQSTM1), which was involved in the degradation of the Nrf2 inhibitor Keap1. Furthermore, our results indicated that the KSHV latent protein vFLIP participates in Nrf2 activation. This study suggests that KSHV hijacks the host's autophagic protein SQSTM1 to induce Nrf2 activation, thereby manipulating the infected host gene regulation to promote KS pathogenesis.
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OWEN CHRISTOPHERB, HUGHES DAVIDJ, BAQUERO-PEREZ BELINDA, BERNDT ANJA, SCHUMANN SOPHIE, JACKSON BRIANR, WHITEHOUSE ADRIAN. Utilising proteomic approaches to understand oncogenic human herpesviruses (Review). Mol Clin Oncol 2014; 2:891-903. [PMID: 25279171 PMCID: PMC4179824 DOI: 10.3892/mco.2014.341] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 06/10/2014] [Indexed: 12/16/2022] Open
Abstract
The γ-herpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus are successful pathogens, each infecting a large proportion of the human population. These viruses persist for the life of the host and may each contribute to a number of malignancies, for which there are currently no cures. Large-scale proteomic-based approaches provide an excellent means of increasing the collective understanding of the proteomes of these complex viruses and elucidating their numerous interactions within the infected host cell. These large-scale studies are important for the identification of the intricacies of viral infection and the development of novel therapeutics against these two important pathogens.
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Affiliation(s)
- CHRISTOPHER B. OWEN
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - DAVID J. HUGHES
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - BELINDA BAQUERO-PEREZ
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - ANJA BERNDT
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - SOPHIE SCHUMANN
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - BRIAN R. JACKSON
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - ADRIAN WHITEHOUSE
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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13
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Ojala PM, Schulz TF. Manipulation of endothelial cells by KSHV: implications for angiogenesis and aberrant vascular differentiation. Semin Cancer Biol 2014; 26:69-77. [PMID: 24486643 DOI: 10.1016/j.semcancer.2014.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/16/2014] [Accepted: 01/16/2014] [Indexed: 12/21/2022]
Abstract
Kaposi sarcoma (KS), a viral cancer associated to Kaposi sarcoma herpesvirus (KSHV) infection, is currently the most common tumor in men in sub-Saharan Africa. KS is an angiogenic tumor and characterized by the presence of aberrant vascular structures in the lesion. Although our understanding of how KSHV causes the aberrant differentiation of endothelial cells and the typical vascular abnormalities in KS tumors is far from complete, the experimental evidence reviewed here provides a comprehensive description of the role of KSHV in the pathogenesis of this unusual tumor. In contrast to other tumor viruses, whose interference with cellular processes relating to cell cycle, apoptosis and DNA damage may be at the heart of their oncogenic properties, KSHV may cause KS primarily by its ability to engage with the differentiation and function of endothelial cells. Although the intracellular pathways engaged by KSHV in the endothelial cells are being explored as drug targets, a better understanding of the impact of KSHV on endothelial cell differentiation and vasculogenesis is needed before the encouraging findings can form the basis for new targeted therapeutic approaches to KS.
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Affiliation(s)
- Päivi M Ojala
- Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 University of Helsinki, Finland; Foundation for the Finnish Cancer Institute, Helsinki, Finland; Section of Virology, Imperial College Faculty of Medicine, Norfolk Place, London W2 1PG, UK.
| | - Thomas F Schulz
- Institute of Virology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Kapoor R, Rizvi F, Kakkar P. Naringenin prevents high glucose-induced mitochondria-mediated apoptosis involving AIF, Endo-G and caspases. Apoptosis 2013. [PMID: 23192364 DOI: 10.1007/s10495-012-0781-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Oxidative stress is implicated in hyperglycemia-induced alterations in cell signaling pathways. We examined the toxicity of high glucose in primary rat hepatocytes and its amelioration by naringenin. Incubation of hepatocytes with 40 mM glucose for 1.5 h exhibited significant decrease in cell viability confirmed by MTT reduction and Alamar blue assay. At the same time primary rat hepatocytes exhibited significant decrease in mitochondrial membrane potential indicating organelle dysfunction. Enhanced translocation of Cyt-c from mitochondria to cytosol and AIF/Endo-G from mitochondria to nucleus, activation of caspase-9/3, DNA damage, and chromatin condensation were observed in glucose-stressed hepatocytes, indicating the involvement of mitochondrial pathway in high glucose-induced apoptosis. Transcript levels of antioxidant enzymes were significantly altered along with corresponding changes in their enzymatic activities. The level of intracellular antioxidant glutathione as well as superoxide dismutase, catalase, and glutathione peroxidase activities were observed to be significantly decreased in hepatocytes treated with high concentration of glucose. Naringenin, a flavanone, was effective in preventing loss of cell viability, reactive oxygen species generation, and decline in antioxidant defense. Translocation of AIF, Endo-G, and Cyt-c from mitochondria was also inhibited by naringenin in glucose-stressed cells. Messenger RNA expression of anti-apoptotic and apoptotic genes, externalization of phosphatidyl serine, DNA damage, chromatin condensation, and sub-diploid cell population were effectively altered by naringenin indicating its anti-apoptotic potential in vitro. Our data suggests that naringenin can prevent apoptosis induced by high glucose through scavenging of reactive oxygen species and modulation of mitochondria-mediated apoptotic pathway.
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Affiliation(s)
- Radhika Kapoor
- Herbal Research Section, CSIR-Indian Institute of Toxicology Research, Lucknow, 226001, India
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15
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Xue M, Guo Y, Yan Q, Qin D, Lu C. Preparation and application of polyclonal antibodiesagainst KSHV v-cyclin. J Biomed Res 2013; 27:421-9. [PMID: 24086175 PMCID: PMC3783827 DOI: 10.7555/jbr.27.20120085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/20/2012] [Accepted: 12/04/2012] [Indexed: 12/12/2022] Open
Abstract
We prepared rabbit polyclonal antibodies against Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded v-cyclin (ORF 72) and detected the natural viral protein using these polyclonal antibodies. Three antigenic polypeptides of v-cyclin were designed and synthesized. A fragment of the v-cyclin gene was cloned into a eukaryotic expression vector pEF-MCS-Flag-IRES/Puro to construct a recombinant vector, pEF v-cyclin. Then, pEF v-cyclin was transfected into 293T and EA.hy926 cells to obtain v-cyclin-Flag fusion proteins. Six New Zealand white rabbits were immunized with KLH-conjugated peptides to generate polyclonal antibodies against v-cyclin. The polyclonal antibodies were then characterized by ELISA and Western blotting assays. Finally, the polyclonal antibodies against v-cyclin were used to detect natural viral protein expressed in BCBL-1, BC-3, and JSC-1 cells. The results showed that using the Flag antibody, v-cyclin-Flag fusion protein was detected in 293T and EA.hy926 cells transfected with pEF-v-cyclin. Furthermore, ELISA showed that the titer of the induced polyclonal rabbit anti-v-cyclin antibodies was higher than 1:8,000. In Western blotting assays, the antibodies reacted specifically with the v-cyclin-Flag fusion protein as well as the natural viral protein. The recombinant expression vector pEF-v-cyclin was constructed successfully, and the polyclonal antibodies prepared can be used for various biological tests including ELISA and Western blotting assays.
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Affiliation(s)
- Min Xue
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing 210029, P. R. China; ; Department of Physiology, Xuzhou Medical College, Xuzhou, Jiangsu, 221000, P. R. China; Jiangsu 223300, China
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16
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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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17
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Sakakibara S, Espigol-Frigole G, Gasperini P, Uldrick TS, Yarchoan R, Tosato G. A20/TNFAIP3 inhibits NF-κB activation induced by the Kaposi's sarcoma-associated herpesvirus vFLIP oncoprotein. Oncogene 2013; 32:1223-32. [PMID: 22525270 PMCID: PMC3594048 DOI: 10.1038/onc.2012.145] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 03/02/2012] [Accepted: 03/05/2012] [Indexed: 12/29/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) K13/vFLIP (viral Flice-inhibitory protein) induces transcription of numerous genes through NF-κB activation, including pro-inflammatory cytokines, which contribute to the pathogenesis of Kaposi's sarcoma (KS). In this study, we report that KSHV vFLIP induces the expression of the NF-κB regulatory proteins A20, ABIN-1 and ABIN-3 (A20-binding NF-κB inhibitors) in primary human endothelial cells, and that KS spindle cells express A20 in KS tissue. In reporter assays, A20 strongly impaired vFLIP-induced NF-κB activation in 293T cells, but ABIN-1 and ABIN-3 did not. Mutational analysis established that the C-terminal domain (residues 427-790) is critical for A20 modulation of NF-κB, but the ubiquitin-editing OTU (ovarian tumor) domain is not. In functional assays, A20 inhibited vFLIP-induced expression of the chemokine IP-10, reduced vFLIP-induced cell proliferation and increased IKK1 protein levels. Thus, we demonstrate that A20 negatively regulates NF-κB activation directly induced by KSHV vFLIP. By attenuating excessive and prolonged vFLIP-induced NF-κB activation that could be harmful to KSHV-infected cells, A20 likely has an important role in the pathogenesis of KSHV-associated diseases, in which vFLIP is expressed.
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Affiliation(s)
- S Sakakibara
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - G Espigol-Frigole
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - P Gasperini
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - TS Uldrick
- HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - R Yarchoan
- HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - G Tosato
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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18
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Bhatt AP, Damania B. AKTivation of PI3K/AKT/mTOR signaling pathway by KSHV. Front Immunol 2013; 3:401. [PMID: 23316192 PMCID: PMC3539662 DOI: 10.3389/fimmu.2012.00401] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 12/12/2012] [Indexed: 12/21/2022] Open
Abstract
As an obligate intracellular parasite, Kaposi sarcoma-associated herpesvirus (KSHV) relies on the host cell machinery to meet its needs for survival, viral replication, production, and dissemination of progeny virions. KSHV is a gammaherpesvirus that is associated with three different malignancies: Kaposi sarcoma (KS), and two B cell lymphoproliferative disorders, primary effusion lymphoma (PEL) and multicentric Castleman’s disease. KSHV viral proteins modulate the cellular phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway, which is a ubiquitous pathway that also controls B lymphocyte proliferation and development. We review the mechanisms by which KSHV manipulates the PI3K/AKT/mTOR pathway, with a specific focus on B cells.
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Affiliation(s)
- Aadra P Bhatt
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Department of Microbiology and Immunology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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Stürzl M, Gaus D, Dirks WG, Ganem D, Jochmann R. Kaposi's sarcoma-derived cell line SLK is not of endothelial origin, but is a contaminant from a known renal carcinoma cell line. Int J Cancer 2012; 132:1954-8. [PMID: 22987579 DOI: 10.1002/ijc.27849] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 09/03/2012] [Indexed: 11/10/2022]
Abstract
Kaposi's sarcoma (KS) is an endothelial cell-derived tumor. Investigations of the molecular mechanisms of KS pathogenesis and the identification of drugs for treatment of KS depend critically on valid cell-culture models. Two major immortalized cell lines are available for KS research. Recently, the KS cell line KS Y-1 has been shown to be cross-contaminated with the T24 urinary bladder cancer cell line (ATCC HTB-4). Here, we show by short tandem repeat profiling that the second KS cell line, SLK, is indistinguishable from the clear-cell renal-cell carcinoma cell line Caki-1. Immunocytochemical detection of cytokeratin expression confirmed the epithelial-cell origin of SLK cells. Our findings indicate that SLK cells are not of endothelial origin and should not be used in future studies as a model for KS-derived endothelial tumor cells. We suggest that in the future, more attention needs to be paid to the authenticity of cells in lines derived from human tissues.
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Affiliation(s)
- Michael Stürzl
- Division of Molecular and Experimental Surgery, Clinical Center Erlangen, Erlangen, Germany.
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20
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Kapoor R, Kakkar P. Protective role of morin, a flavonoid, against high glucose induced oxidative stress mediated apoptosis in primary rat hepatocytes. PLoS One 2012; 7:e41663. [PMID: 22899998 PMCID: PMC3416810 DOI: 10.1371/journal.pone.0041663] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 06/22/2012] [Indexed: 01/24/2023] Open
Abstract
Apoptosis is an early event of liver damage in diabetes and oxidative stress has been linked to accelerate the apoptosis in hepatocytes. Therefore, the compounds that can scavenge ROS may confer regulatory effects on high-glucose induced apoptosis. In the present study, primary rat hepatocytes were exposed to high concentration (40 mM) of glucose. At this concentration decreased cell viability and enhanced ROS generation was observed. Depleted antioxidant status of hepatocytes under high glucose stress was also observed as evident from transcriptional level and activities of antioxidant enzymes. Further, mitochondrial depolarisation was accompanied by the loss of mitochondrial integrity and altered expression of Bax and Bcl-2. Increased translocation of apoptotic proteins like AIF (Apoptosis inducing factor) & Endo-G (endonuclease-G) from its resident place mitochondria to nucleus was also observed. Cyt-c residing in the inter-membrane space of mitochondria also translocated to cytoplasm. These apoptotic proteins initiated caspase activation, DNA fragmentation, chromatin condensation, increased apoptotic DNA content in glucose treated hepatocytes, suggesting mitochondria mediated apoptotic mode of cell death. Morin, a dietary flavonoid from Psidium guajava was effective in increasing the cell viability and decreasing the ROS level. It maintained mitochondrial integrity, inhibited release of apoptotic proteins from mitochondria, prevented DNA fragmentation, chromatin condensation and hypodiploid DNA upon exposure to high glucose. This study confirms the capacity of dietary flavonoid Morin in regulating apoptosis induced by high glucose via mitochondrial mediated pathway through intervention of oxidative stress.
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Affiliation(s)
- Radhika Kapoor
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Poonam Kakkar
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
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Viral FLICE inhibitory protein of rhesus monkey rhadinovirus inhibits apoptosis by enhancing autophagosome formation. PLoS One 2012; 7:e39438. [PMID: 22745754 PMCID: PMC3380001 DOI: 10.1371/journal.pone.0039438] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 05/23/2012] [Indexed: 11/19/2022] Open
Abstract
Rhesus monkey rhadinovirus (RRV) is a gamma-2 herpesvirus closely related to human herpesvirus 8 (HHV8). RRV encodes viral FLICE inhibitory protein (vFLIP), which has death effector domains. Little is known about RRV vFLIP. This study intended to examine its function in apoptosis. Here we found that RRV vFLIP inhibits apoptosis induced by tumor necrosis factor-α (TNF-α) and cycloheximide. In HeLa cells with vFLIP expression, the cleavage of poly [ADP-ribose] polymerase 1 (PARP-1) and activities of caspase 3, 7, and 9 were much lower than those in controls. Cell viability of HeLa cells with vFLIP expression was significantly higher than control cells after apoptosis induction. However, RRV vFLIP appears unable to induce NF-κB signaling when tested in NF-κB reporter assay. RRV vFLIP was able to enhance cell survival under starved conditions or apoptosis induction. At early time points after apoptosis induction, autophagosome formation was enhanced and LC3-II level was elevated in cells with vFLIP and, when autophagy was blocked with chemical inhibitors, these cells underwent apoptosis. Moreover, RRV latent infection of BJAB B-lymphoblastoid cells protects the cells against apoptosis by enhancing autophagy to maintain cell survival. Knockdown of vFLIP expression in the RRV-infected BJAB cells with siRNA abolished the protection against apoptosis. These results indicate that vFLIP protects cells against apoptosis by enhancing autophagosome formation to extend cell survival. The finding of vFLIP’s inhibition of apoptosis via the autophagy pathway provides insights of vFLIP in RRV pathogenesis.
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Deletion of Kaposi's sarcoma-associated herpesvirus FLICE inhibitory protein, vFLIP, from the viral genome compromises the activation of STAT1-responsive cellular genes and spindle cell formation in endothelial cells. J Virol 2011; 85:10375-88. [PMID: 21795355 DOI: 10.1128/jvi.00226-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Kaposi's sarcoma herpesvirus (KSHV) Fas-associated death domain (FADD)-like interleukin-1 beta-converting enzyme (FLICE)-inhibitory protein, vFLIP, has antiapoptotic properties, is a potent activator of the NF-κB pathway, and induces the formation of endothelial spindle cells, the hallmark of Kaposi's sarcoma, when overexpressed in primary endothelial cells. We used a reverse genetics approach to study several functions of KSHV vFLIP in the context of the whole viral genome. Deletion of the gene encoding vFLIP from a KSHV genome cloned in a bacterial artificial chromosome (BAC) reduced the ability of the virus to persist and induce spindle cell formation in primary human umbilical vein endothelial cells (HUVECs). Only a few, mainly interferon (IFN)-responsive, genes were expressed in wild-type KSHV (KSHV-wt)-infected endothelial cells at levels higher than those in KSHV-ΔFLIP-infected endothelial cells, in contrast to the plethora of cellular genes induced by overexpressed vFLIP. In keeping with this observation, vFLIP induces the phosphorylation of STAT1 and STAT2 in an NF-κB-dependent manner in endothelial cells. vFLIP-dependent phosphorylation of STAT1 and STAT2 could be demonstrated after endothelial cells were infected with KSHV-wt, KSHV-ΔFLIP, and a KSHV-vFLIP revertant virus. These findings document the impact of KSHV vFLIP on the transcriptome of primary endothelial cells during viral persistence and highlight the role of vFLIP in the activation of STAT1/STAT2 and STAT-responsive cellular genes by KSHV.
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Guryanova OA, Drazba JA, Frolova EI, Chumakov PM. Actin cytoskeleton remodeling by the alternatively spliced isoform of PDLIM4/RIL protein. J Biol Chem 2011; 286:26849-59. [PMID: 21636573 DOI: 10.1074/jbc.m111.241554] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
RIL (product of PDLIM4 gene) is an actin-associated protein that has previously been shown to stimulate actin bundling by interacting with actin-cross-linking protein α-actinin-1 and increasing its affinity to filamentous actin. Here, we report that the alternatively spliced isoform of RIL, denoted here as RILaltCterm, functions as a dominant-negative modulator of RIL-mediated actin reorganization. RILaltCterm is regulated at the level of protein stability, and this protein isoform accumulates particularly in response to oxidative stress. We show that the alternative C-terminal segment of RILaltCterm has a disordered structure that directs the protein to rapid degradation in the core 20 S proteasomes. Such degradation is ubiquitin-independent and can be blocked by binding to NAD(P)H quinone oxidoreductase NQO1, a detoxifying enzyme induced by prolonged exposure to oxidative stress. We show that either overexpression of RILaltCterm or its stabilization by stresses counteracts the effects produced by full-length RIL on organization of actin cytoskeleton and cell motility. Taken together, the data suggest a mechanism for fine-tuning actin cytoskeleton rearrangement in response to stresses.
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Affiliation(s)
- Olga A Guryanova
- Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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Konrad A, Jochmann R, Kuhn E, Naschberger E, Chudasama P, Stürzl M. Reverse transfected cell microarrays in infectious disease research. Methods Mol Biol 2011; 706:107-18. [PMID: 21104058 DOI: 10.1007/978-1-61737-970-3_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Several human pathogenic viruses encode large genomes with often more than 100 genes. Viral pathogenicity is determined by carefully orchestrated co-operative activities of several different viral genes which trigger the phenotypic functions of the infected cells. Systematic analyses of these complex interactions require high-throughput transfection technology. Here we have provided a laboratory manual for the reverse transfected cell microarray (RTCM; alternative name: cell chip) as a high-throughput transfection procedure, which has been successfully applied for the systematic analyses of single and combination effects of genes encoded by the human herpesvirus-8 on the NF-kappaB signal transduction pathway. In order to quantitatively determine the effects of viral genes in transfected cells, protocols for the use of GFP as an indicator gene and for indirect immunofluorescence staining of cellular target proteins have been included. RTCM provides a useful methodological approach to investigate systematically combination effects of viral genes on cellular functions.
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Affiliation(s)
- Andreas Konrad
- Division of Molecular and Experimental Surgery, Department of Surgery, University Medical Center Erlangen, Erlangen, Germany.
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Saha A, Kaul R, Murakami M, Robertson ES. Tumor viruses and cancer biology: Modulating signaling pathways for therapeutic intervention. Cancer Biol Ther 2010; 10:961-78. [PMID: 21084867 DOI: 10.4161/cbt.10.10.13923] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Tumor viruses have provided relatively simple genetic systems, which can be manipulated for understanding the molecular mechanisms of the cellular transformation process. A growing body of information in the tumor virology field provides several prospects for rationally targeted therapies. However, further research is needed to better understand the multiple mechanisms utilized by these viruses in cancer progression in order to develop therapeutic strategies. Initially viruses were believed to be associated with cancers as causative agents only in animals. It was almost half a century before the first human tumor virus, Epstein-Barr virus (EBV), was identified in 1964. Subsequently, several human tumor viruses have been identified including Kaposi sarcoma associated herpesvirus (KSHV), human Papillomaviruses (HPV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human T lymphotropic virus (HTLV-1) and recently identified Merkel cell Polyomavirus (MCPyV). Tumor viruses are sub-categorized as either DNA viruses, which include EBV, KSHV, HPV, HBV, and MCPyV, or RNA viruses such as HCV and HTLV-1. Tumor-viruses induce oncogenesis through manipulating an array of different cellular pathways. These viruses initiate a series of cellular events, which lead to immortalization and proliferation of the infected cells by disrupting the mitotic checkpoint upon infection of the host cell. This is often accomplished by functional inhibition or proteasomal degradation of many tumor suppressor proteins by virally encoded gene products. The virally infected cells can either be eliminated via cell-mediated apoptosis or persist in a state of chronic infection. Importantly, the chronic persistence of infection by tumor viruses can lead to oncogenesis. This review discusses the major human tumor associated viruses and their ability to modulate numerous cell signaling pathways, which can be targeted for potential therapeutic approaches.
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Affiliation(s)
- Abhik Saha
- Department of Microbiology and Tumor Virology, University of Pennsylvania School of Medicine, Philadelphia, USA
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Ahmad A, Groshong JS, Matta H, Schamus S, Punj V, Robinson LJ, Gill PS, Chaudhary PM. Kaposi sarcoma-associated herpesvirus-encoded viral FLICE inhibitory protein (vFLIP) K13 cooperates with Myc to promote lymphoma in mice. Cancer Biol Ther 2010; 10:1033-40. [PMID: 20818173 DOI: 10.4161/cbt.10.10.13291] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Primary effusion lymphoma (PEL) is an aggressive form of lymphoma that is associated with infection by Kaposi's sarcoma-associated herpesvirus (KSHV). One of the KSHV genes expressed in PEL cells is K13, a potent activator of the NF-κB pathway. K13 transgenic mice develop lymphomas, but after a long period of latency. A possible candidate that could cooperate with K13 in the development of PEL is c-Myc, whose expression is frequently dysregulated in PEL cells. To study the cooperative interaction between K13 and c-Myc in the pathogenesis of PEL, we crossed the K13 transgenic mice to iMyc(Eμ) transgenic mice that overexpress Myc. We report that lymphomas in the K13/iMyc(Eμ) double transgenic mice developed with shorter latency and were histologically distinct from those observed in the iMyc(Eμ) mice. Lymphomas in the K13/iMyc(Eμ) mice also lacked the expression of B- and T-cell markers, thus resembling the immunophenotype of PEL. The accelerated development of lymphoma in the K13/iMyc(Eμ) mice was associated with increased expression of K13, elevated NF-κB activity and decrease in apoptosis. Taken collectively, our results demonstrate a cooperative interaction between the NF-κB and Myc pathways in lymphomagenesis.
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Affiliation(s)
- Anwaar Ahmad
- Department of Medicine, University of Pittsburgh Cancer Institute, PA, USA
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Oxidative stress induces reactivation of Kaposi's sarcoma-associated herpesvirus and death of primary effusion lymphoma cells. J Virol 2010; 85:715-24. [PMID: 21068240 DOI: 10.1128/jvi.01742-10] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL) cells are predominantly infected with latent Kaposi's sarcoma-associated herpesvirus (KSHV), presenting a barrier to the destruction of tumor cells. Latent KSHV can be reactivated to undergo lytic replication. Here we report that in PEL cells, oxidative stress induced by upregulated reactive oxygen species (ROS) can lead to KSHV reactivation or cell death. ROS are upregulated by NF-κB inhibition and are required for subsequent KSHV reactivation. Disruption of the intracellular redox balance through depletion of the antioxidant glutathione or inhibition of the antioxidant enzyme catalase also induces KSHV reactivation, suggesting that hydrogen peroxide induces reactivation. In addition, p38 signaling is required for KSHV reactivation induced by ROS. Furthermore, treatment of PEL cells with a higher concentration of the NF-κB inhibitor than that used for inducing KSHV reactivation further upregulates ROS and induces massive cell death. ROS, but not p38 signaling, are required for PEL cell death induced by NF-κB inhibition as well as by glutathione depletion. Importantly, anticancer drugs, such as cisplatin and arsenic trioxide, also induce KSHV reactivation and PEL cell death in a ROS-dependent manner. Our study thus establishes a critical role for ROS and oxidative stress in the regulation of KSHV reactivation and PEL cell death. Disrupting the cellular redox balance may be a potential strategy for treating KSHV-associated lymphoma.
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Abstract
Latency is a state of cryptic viral infection associated with genomic persistence and highly restricted gene expression. Its hallmark is reversibility: under appropriate circumstances, expression of the entire viral genome can be induced, resulting in the production of infectious progeny. Among the small number of virus families capable of authentic latency, the herpesviruses stand out for their ability to produce such infections in every infected individual and for being completely dependent upon latency as a mode of persistence. Here, we review the molecular basis of latency, with special attention to the gamma-herpesviruses, in which the understanding of this process is most advanced.
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Affiliation(s)
- Samuel H Speck
- Emory Vaccine Center, Emory University, Atlanta, GA 30322, USA
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Human herpesvirus 8 viral FLICE-inhibitory protein retards cell proliferation via downregulation of Id2 and Id3 expression. Mol Cell Biochem 2010; 343:83-9. [PMID: 20512523 DOI: 10.1007/s11010-010-0501-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Accepted: 05/12/2010] [Indexed: 10/19/2022]
Abstract
Death receptor-mediated apoptosis is potently inhibited by viral FLIP (FLICE/caspase 8 inhibitory protein) through reduced activation of procaspase 8. In this study, we show that the human herpesvirus 8-encoded vFLIP retards cell proliferation. Overexpression of vFLIP caused cell cycle arrest, with an apparent decrease of cells in the S phase. The Id (inhibitor of DNA binding) proteins are considered as dominant negative regulators of differentiation pathways, but positive regulators of cellular proliferation. The mechanisms by which Id proteins promote the cell cycle are diverse, but appear to involve affecting the expression of cell cycle regulators. RT-PCR results demonstrated that the expression of vFLIP decreased the expression levels of Id2 and Id3 as well as cyclin E and cyclin A compared with the vFLIP-null cells. These indicate that vFLIP affects cell proliferation by decreasing the expression levels of cell cycle regulatory proteins.
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Ganem D. KSHV and the pathogenesis of Kaposi sarcoma: listening to human biology and medicine. J Clin Invest 2010; 120:939-49. [PMID: 20364091 DOI: 10.1172/jci40567] [Citation(s) in RCA: 274] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The linkage of Kaposi sarcoma (KS) to infection by a novel human herpesvirus (Kaposi sarcoma-associated herpesvirus [KSHV]) is one of the great successes of contemporary biomedical research and was achieved by using advanced genomic technologies in a manner informed by a nuanced understanding of epidemiology and clinical investigation. Ongoing efforts to understand the molecular mechanisms by which KSHV infection predisposes to KS continue to be powerfully influenced by insights emanating from the clinic. Here, recent developments in KS pathogenesis are reviewed, with particular emphasis on clinical, pathologic, and molecular observations that highlight the many differences between this process and tumorigenesis by other oncogenic viruses.
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Affiliation(s)
- Don Ganem
- Department of Medicine and Microbiology, University of California, 513 Parnassus Ave., San Francisco, CA 91413, USA.
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Qin Z, Freitas E, Sullivan R, Mohan S, Bacelieri R, Branch D, Romano M, Kearney P, Oates J, Plaisance K, Renne R, Kaleeba J, Parsons C. Upregulation of xCT by KSHV-encoded microRNAs facilitates KSHV dissemination and persistence in an environment of oxidative stress. PLoS Pathog 2010; 6:e1000742. [PMID: 20126446 PMCID: PMC2813276 DOI: 10.1371/journal.ppat.1000742] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Accepted: 12/29/2009] [Indexed: 01/13/2023] Open
Abstract
Upregulation of xCT, the inducible subunit of a membrane-bound amino acid transporter, replenishes intracellular glutathione stores to maintain cell viability in an environment of oxidative stress. xCT also serves as a fusion-entry receptor for the Kaposi's sarcoma-associated herpesvirus (KSHV), the causative agent of Kaposi's sarcoma (KS). Ongoing KSHV replication and infection of new cell targets is important for KS progression, but whether xCT regulation within the tumor microenvironment plays a role in KS pathogenesis has not been determined. Using gene transfer and whole virus infection experiments, we found that KSHV-encoded microRNAs (KSHV miRNAs) upregulate xCT expression by macrophages and endothelial cells, largely through miR-K12-11 suppression of BACH-1-a negative regulator of transcription recognizing antioxidant response elements within gene promoters. Correlative functional studies reveal that upregulation of xCT by KSHV miRNAs increases cell permissiveness for KSHV infection and protects infected cells from death induced by reactive nitrogen species (RNS). Interestingly, KSHV miRNAs simultaneously upregulate macrophage secretion of RNS, and biochemical inhibition of RNS secretion by macrophages significantly reduces their permissiveness for KSHV infection. The clinical relevance of these findings is supported by our demonstration of increased xCT expression within more advanced human KS tumors containing a larger number of KSHV-infected cells. Collectively, these data support a role for KSHV itself in promoting de novo KSHV infection and the survival of KSHV-infected, RNS-secreting cells in the tumor microenvironment through the induction of xCT.
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Affiliation(s)
- Zhiqiang Qin
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Craniofacial Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Eduardo Freitas
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Roger Sullivan
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Sarumathi Mohan
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Rocky Bacelieri
- Department of Dermatology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Drake Branch
- Department of Dermatology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Margaret Romano
- Department of Pathology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Patricia Kearney
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Jim Oates
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Medical Service, Ralph H. Johnson VA Medical Center, Charleston, South Carolina, United States of America
| | - Karlie Plaisance
- Department of Molecular Genetics and Microbiology, Shands Cancer Center, University of Florida, Gainesville, Florida, United States of America
| | - Rolf Renne
- Department of Molecular Genetics and Microbiology, Shands Cancer Center, University of Florida, Gainesville, Florida, United States of America
| | - Johnan Kaleeba
- Departments of Microbiology and Immunology and Molecular/Cell Biology, Uniformed Services University of the Health Sciences, F. Edward Herbert School of Medicine, Bethesda, Maryland, United States of America
| | - Chris Parsons
- Department of Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Craniofacial Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
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Punj V, Matta H, Schamus S, Tamewitz A, Anyang B, Chaudhary PM. Kaposi's sarcoma-associated herpesvirus-encoded viral FLICE inhibitory protein (vFLIP) K13 suppresses CXCR4 expression by upregulating miR-146a. Oncogene 2009; 29:1835-44. [PMID: 20023696 PMCID: PMC2845732 DOI: 10.1038/onc.2009.460] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Kaposi's sarcoma (KS)-associated herpesvirus (KSHV)-encoded viral FLICE inhibitory protein (vFLIP) K13 is a potent activator of the nuclear factor-kappaB (NF-kappaB) pathway. In this study, we show that infection with KHSV and ectopic expression of K13, but not its NF-kappaB-defective mutant, suppressed the expression of CXCR4. Suppression of CXCR4 by KSHV and K13 was associated with upregulated expression of miR-146a, a microRNA that is known to bind to the 3'-untranslated region of CXCR4 mRNA. Reporter studies identified two NF-kappaB sites in the promoter of miR-146a that were essential for its activation by K13. Accordingly, ectopic expression of K13, but not its NF-kappaB-defective mutant or other vFLIPs, strongly stimulated the miR-146a promoter activity, which could be blocked by specific genetic and pharmacological inhibitors of the NF-kappaB pathway. Finally, expression of CXCR4 was downregulated in clinical samples of KS and this was accompanied by an increased expression of miR-146a. Our results show that K13-induced NF-kappaB activity suppresses CXCR4 through upregulation of miR-146a. Downregulation of CXCR4 expression by K13 may contribute to KS development by promoting premature release of KSHV-infected endothelial progenitors into the circulation.
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Affiliation(s)
- V Punj
- Division of Hematology-Oncology, Department of Medicine, Hillman Cancer Center, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA 15213-1863, USA
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Punj V, Matta H, Schamus S, Chaudhary PM. Integrated microarray and multiplex cytokine analyses of Kaposi's Sarcoma Associated Herpesvirus viral FLICE Inhibitory Protein K13 affected genes and cytokines in human blood vascular endothelial cells. BMC Med Genomics 2009; 2:50. [PMID: 19660139 PMCID: PMC2732924 DOI: 10.1186/1755-8794-2-50] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Accepted: 08/06/2009] [Indexed: 11/10/2022] Open
Abstract
Background Kaposi's sarcoma (KS) associated herpesvirus (KSHV) is the etiological agent of KS, a neoplasm characterized by proliferating spindle cells, extensive neoangiogenesis and a prominent inflammatory infiltrate. Infection of blood vascular endothelial cells with KSHV in vitro results in their spindle cell transformation, which is accompanied by increased expression of inflammatory chemokines and cytokines, and acquisition of lymphatic endothelial markers. Mimicking the effect of viral infection, ectopic expression of KSHV-encoded latent protein vFLIP K13 is sufficient to induce spindle transformation of vascular endothelial cells. However, the effect of K13 expression on global gene expression and induction of lymphatic endothelial markers in vascular endothelial cells has not been studied. Methods We used gene array analysis to determine change in global gene expression induced by K13 in human vascular endothelial cells (HUVECs). Results of microarray analysis were validated by quantitative RT-PCR, immunoblotting and a multiplex cytokine array. Results K13 affected the expression of several genes whose expression is known to be modulated by KSHV infection, including genes involved in immune and inflammatory responses, anti-apoptosis, stress response, and angiogenesis. The NF-κB pathway was the major signaling pathway affected by K13 expression, and genetic and pharmacological inhibitors of this pathway effectively blocked K13-induced transcriptional activation of the promoter of CXCL10, one of the chemokines whose expression was highly upregulated by K13. However, K13, failed to induce expression of lymphatic markers in blood vascular endothelial cells. Conclusion While K13 may account for change in the expression of a majority of genes observed following KSHV infection, it is not sufficient for inducing lymphatic reprogramming of blood vascular endothelial cells.
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Affiliation(s)
- Vasu Punj
- Department of Medicine, Division of Hematology-Oncology, Hillman Cancer Center, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA, USA.
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O-linked N-acetylglucosaminylation of Sp1 inhibits the human immunodeficiency virus type 1 promoter. J Virol 2009; 83:3704-18. [PMID: 19193796 DOI: 10.1128/jvi.01384-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) gene expression and replication are regulated by the promoter/enhancer located in the U3 region of the proviral 5' long terminal repeat (LTR). The binding of cellular transcription factors to specific regulatory sites in the 5' LTR is a key event in the replication cycle of HIV-1. Since transcriptional activity is regulated by the posttranslational modification of transcription factors with the monosaccharide O-linked N-acetyl-D-glucosamine (O-GlcNAc), we evaluated whether increased O-GlcNAcylation affects HIV-1 transcription. In the present study we demonstrate that treatment of HIV-1-infected lymphocytes with the O-GlcNAcylation-enhancing agent glucosamine (GlcN) repressed viral transcription in a dose-dependent manner. Overexpression of O-GlcNAc transferase (OGT), the sole known enzyme catalyzing the addition of O-GlcNAc to proteins, specifically inhibited the activity of the HIV-1 LTR promoter in different T-cell lines and in primary CD4(+) T lymphocytes. Inhibition of HIV-1 LTR activity in infected T cells was most efficient (>95%) when OGT was recombinantly overexpressed prior to infection. O-GlcNAcylation of the transcription factor Sp1 and the presence of Sp1-binding sites in the LTR were found to be crucial for this inhibitory effect. From this study, we conclude that O-GlcNAcylation of Sp1 inhibits the activity of the HIV-1 LTR promoter. Modulation of Sp1 O-GlcNAcylation may play a role in the regulation of HIV-1 latency and activation and links viral replication to the glucose metabolism of the host cell. Hence, the establishment of a metabolic treatment might supplement the repertoire of antiretroviral therapies against AIDS.
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A systems biology approach to identify the combination effects of human herpesvirus 8 genes on NF-kappaB activation. J Virol 2009; 83:2563-74. [PMID: 19129458 DOI: 10.1128/jvi.01512-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Human herpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma and primary effusion lymphoma. Activation of the cellular transcription factor nuclear factor-kappa B (NF-kappaB) is essential for latent persistence of HHV-8, survival of HHV-8-infected cells, and disease progression. We used reverse-transfected cell microarrays (RTCM) as an unbiased systems biology approach to systematically analyze the effects of HHV-8 genes on the NF-kappaB signaling pathway. All HHV-8 genes individually (n = 86) and, additionally, all K and latent genes in pairwise combinations (n = 231) were investigated. Statistical analyses of more than 14,000 transfections identified ORF75 as a novel and confirmed K13 as a known HHV-8 activator of NF-kappaB. K13 and ORF75 showed cooperative NF-kappaB activation. Small interfering RNA-mediated knockdown of ORF75 expression demonstrated that this gene contributes significantly to NF-kappaB activation in HHV-8-infected cells. Furthermore, our approach confirmed K10.5 as an NF-kappaB inhibitor and newly identified K1 as an inhibitor of both K13- and ORF75-mediated NF-kappaB activation. All results obtained with RTCM were confirmed with classical transfection experiments. Our work describes the first successful application of RTCM for the systematic analysis of pathofunctions of genes of an infectious agent. With this approach, ORF75 and K1 were identified as novel HHV-8 regulatory molecules on the NF-kappaB signal transduction pathway. The genes identified may be involved in fine-tuning of the balance between latency and lytic replication, since this depends critically on the state of NF-kappaB activity.
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