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Molnar T, Lehoczki A, Fekete M, Varnai R, Zavori L, Erdo-Bonyar S, Simon D, Berki T, Csecsei P, Ezer E. Mitochondrial dysfunction in long COVID: mechanisms, consequences, and potential therapeutic approaches. GeroScience 2024; 46:5267-5286. [PMID: 38668888 PMCID: PMC11336094 DOI: 10.1007/s11357-024-01165-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Accepted: 04/15/2024] [Indexed: 08/22/2024] Open
Abstract
The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has introduced the medical community to the phenomenon of long COVID, a condition characterized by persistent symptoms following the resolution of the acute phase of infection. Among the myriad of symptoms reported by long COVID sufferers, chronic fatigue, cognitive disturbances, and exercise intolerance are predominant, suggesting systemic alterations beyond the initial viral pathology. Emerging evidence has pointed to mitochondrial dysfunction as a potential underpinning mechanism contributing to the persistence and diversity of long COVID symptoms. This review aims to synthesize current findings related to mitochondrial dysfunction in long COVID, exploring its implications for cellular energy deficits, oxidative stress, immune dysregulation, metabolic disturbances, and endothelial dysfunction. Through a comprehensive analysis of the literature, we highlight the significance of mitochondrial health in the pathophysiology of long COVID, drawing parallels with similar clinical syndromes linked to post-infectious states in other diseases where mitochondrial impairment has been implicated. We discuss potential therapeutic strategies targeting mitochondrial function, including pharmacological interventions, lifestyle modifications, exercise, and dietary approaches, and emphasize the need for further research and collaborative efforts to advance our understanding and management of long COVID. This review underscores the critical role of mitochondrial dysfunction in long COVID and calls for a multidisciplinary approach to address the gaps in our knowledge and treatment options for those affected by this condition.
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Affiliation(s)
- Tihamer Molnar
- Department of Anaesthesiology and Intensive Care, Medical School, University of Pecs, Pecs, Hungary
| | - Andrea Lehoczki
- Doctoral College, Health Sciences Program, Semmelweis University, Budapest, Hungary
- Department of Haematology and Stem Cell Transplantation, National Institute for Haematology and Infectious Diseases, South Pest Central Hospital, 1097, Budapest, Hungary
- Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Monika Fekete
- Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Reka Varnai
- Department of Primary Health Care, Medical School University of Pecs, Pecs, Hungary
| | | | - Szabina Erdo-Bonyar
- Department of Immunology and Biotechnology, Medical School, University of Pecs, Pecs, Hungary
| | - Diana Simon
- Department of Immunology and Biotechnology, Medical School, University of Pecs, Pecs, Hungary
| | - Tímea Berki
- Department of Immunology and Biotechnology, Medical School, University of Pecs, Pecs, Hungary
| | - Peter Csecsei
- Department of Neurosurgery, Medical School, University of Pecs, Ret U 2, 7624, Pecs, Hungary.
| | - Erzsebet Ezer
- Department of Anaesthesiology and Intensive Care, Medical School, University of Pecs, Pecs, Hungary
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2
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Wyżewski Z, Mielcarska MB, Gregorczyk-Zboroch KP, Myszka A. Virus-Mediated Inhibition of Apoptosis in the Context of EBV-Associated Diseases: Molecular Mechanisms and Therapeutic Perspectives. Int J Mol Sci 2022; 23:ijms23137265. [PMID: 35806271 PMCID: PMC9266970 DOI: 10.3390/ijms23137265] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 12/10/2022] Open
Abstract
Epstein-Barr virus (EBV), the representative of the Herpesviridae family, is a pathogen extensively distributed in the human population. One of its most characteristic features is the capability to establish latent infection in the host. The infected cells serve as a sanctuary for the dormant virus, and therefore their desensitization to apoptotic stimuli is part of the viral strategy for long-term survival. For this reason, EBV encodes a set of anti-apoptotic products. They may increase the viability of infected cells and enhance their resistance to chemotherapy, thereby contributing to the development of EBV-associated diseases, including Burkitt’s lymphoma (BL), Hodgkin’s lymphoma (HL), gastric cancer (GC), nasopharyngeal carcinoma (NPC) and several other malignancies. In this paper, we have described the molecular mechanism of anti-apoptotic actions of a set of EBV proteins. Moreover, we have reviewed the pro-survival role of non-coding viral transcripts: EBV-encoded small RNAs (EBERs) and microRNAs (miRNAs), in EBV-carrying malignant cells. The influence of EBV on the expression, activity and/or intracellular distribution of B-cell lymphoma 2 (Bcl-2) protein family members, has been presented. Finally, we have also discussed therapeutic perspectives of targeting viral anti-apoptotic products or their molecular partners.
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Affiliation(s)
- Zbigniew Wyżewski
- Institute of Biological Sciences, Cardinal Stefan Wyszyński University, Dewajtis 5, 01-815 Warsaw, Poland;
- Correspondence: ; Tel.: +48-728-208-338
| | - Matylda Barbara Mielcarska
- Institute of Veterinary Medicine, Warsaw University of Life Sciences—SGGW, Nowoursynowska 166, 02-787 Warsaw, Poland; (M.B.M.); (K.P.G.-Z.)
| | | | - Anna Myszka
- Institute of Biological Sciences, Cardinal Stefan Wyszyński University, Dewajtis 5, 01-815 Warsaw, Poland;
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3
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The interplay between Epstein-Bar virus (EBV) with the p53 and its homologs during EBV associated malignancies. Heliyon 2019; 5:e02624. [PMID: 31840114 PMCID: PMC6893087 DOI: 10.1016/j.heliyon.2019.e02624] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 07/26/2019] [Accepted: 10/08/2019] [Indexed: 12/12/2022] Open
Abstract
p53, p63, and p73, the members of the p53 family of proteins, are structurally similar proteins that play central roles regulating cell cycle and apoptotic cell death. Alternative splicing at the carboxyl terminus and the utilization of different promoters further categorizes these proteins as having different isoforms for each. Among such isoforms, TA and ΔN versions of each protein serve as the pro and the anti-apoptotic proteins, respectively. Changes in the expression patterns of these isoforms are noted in many human cancers. Proteins of certain human herpesviruses, like Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), interact with p53 family members and alter their expressions in many malignancies. Upon infections in the B cells and epithelial cells, EBV expresses different lytic or latent proteins during viral replication and latency respectively to preserve viral copy number, chromosomal integrity and viral persistence inside the host. In this review, we have surveyed and summarised the interactions of EBV gene products, known so far, with the p53 family proteins. The interactions between P53 and EBV oncoproteins are observed in stomach cancer, non-Hodgkin's lymphoma (NHL) of the head and neck, Nasopharyngeal Cancer (NPC), Gastric carcinoma (GC) and Burkitt's lymphoma (BL). EBV latent protein EBNA1, EBNA3C, LMP-1, and lytic proteins BZLF-1 can alter p53 expressions in many cancer cell lines. Interactions of p63 with EBNA-1, 2, 5, LMP-2A and BARF-1 have also been investigated in several cancers. Similarly, associations of p73 isoform with EBV latent proteins EBNA3C and LMP-1 have been reported. Methylation and single nucleotide polymorphisms in p53 have also been found to be correlated with EBV infection. Therefore, interactions and altered expression strategies of the isoforms of p53 family proteins in EBV associated cancers propose an important field for further molecular research.
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4
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Fitzsimmons L, Kelly GL. EBV and Apoptosis: The Viral Master Regulator of Cell Fate? Viruses 2017; 9:E339. [PMID: 29137176 PMCID: PMC5707546 DOI: 10.3390/v9110339] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/08/2017] [Accepted: 11/09/2017] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV) was first discovered in cells from a patient with Burkitt lymphoma (BL), and is now known to be a contributory factor in 1-2% of all cancers, for which there are as yet, no EBV-targeted therapies available. Like other herpesviruses, EBV adopts a persistent latent infection in vivo and only rarely reactivates into replicative lytic cycle. Although latency is associated with restricted patterns of gene expression, genes are never expressed in isolation; always in groups. Here, we discuss (1) the ways in which the latent genes of EBV are known to modulate cell death, (2) how these mechanisms relate to growth transformation and lymphomagenesis, and (3) how EBV genes cooperate to coordinately regulate key cell death pathways in BL and lymphoblastoid cell lines (LCLs). Since manipulation of the cell death machinery is critical in EBV pathogenesis, understanding the mechanisms that underpin EBV regulation of apoptosis therefore provides opportunities for novel therapeutic interventions.
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Affiliation(s)
- Leah Fitzsimmons
- Institute of Cancer and Genomic Sciences and Centre for Human Virology, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Gemma L Kelly
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute for Medical Research, Parkville, Melbourne, VIC 3052, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, Melbourne, VIC 3052, Australia.
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5
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Girkin JL, Hatchwell LM, Collison AM, Starkey MR, Hansbro PM, Yagita H, Foster PS, Mattes J. TRAIL signaling is proinflammatory and proviral in a murine model of rhinovirus 1B infection. Am J Physiol Lung Cell Mol Physiol 2016; 312:L89-L99. [PMID: 27836899 DOI: 10.1152/ajplung.00200.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 11/04/2016] [Indexed: 02/07/2023] Open
Abstract
the aim of this study is to elucidate the role of TRAIL during rhinovirus (RV) infection in vivo. Naïve wild-type and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-deficient (Tnfsf10-/-) BALB/c mice were infected intranasally with RV1B. In separate experiments, Tnfsf10-/- mice were sensitized and challenged via the airway route with house dust mite (HDM) to induce allergic airways disease and then challenged with RVIB or UV-RVIB. Airway hyperreactivity (AHR) was invasively assessed as total airways resistance in response to increasing methacholine challenge and inflammation was assessed in bronchoalveolar lavage fluid at multiple time points postinfection. Chemokines were quantified by ELISA of whole lung lysates and viral load was determined by quantitative RT-PCR and tissue culture infective dose (TCID50). Human airway epithelial cells (BEAS2B) were infected with RV1B and stimulated with recombinant TRAIL or neutralizing anti-TRAIL antibodies and viral titer assessed by TCID50 HDM-challenged Tnfsf10-/- mice were protected against RV-induced AHR and had suppressed cellular infiltration in the airways upon RV infection. Chemokine C-X-C-motif ligand 2 (CXCL2) production was suppressed in naïve Tnfsf10-/- mice infected with RV1B, with less RV1B detected 24 h postinfection. This was associated with reduced apoptotic cell death and a reduction of interferon (IFN)-λ2/3 but not IFN-α or IFN-β. TRAIL stimulation increased, whereas anti-TRAIL antibodies reduced viral replication in RV1B-infected BEAS2B cells in vitro. In conclusion, TRAIL promotes RV-induced AHR, inflammation and RV1B replication, implicating this molecule and its downstream signaling pathways as a possible target for the amelioration of RV1B-induced allergic and nonallergic lung inflammation and AHR.
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Affiliation(s)
- Jason L Girkin
- Experimental and Translational Respiratory Medicine Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Priority Research Centre for Healthy Lungs, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Luke M Hatchwell
- Experimental and Translational Respiratory Medicine Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Priority Research Centre GrowUpWell, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Adam M Collison
- Experimental and Translational Respiratory Medicine Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Priority Research Centre GrowUpWell, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Malcolm R Starkey
- Priority Research Centre for Healthy Lungs, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Priority Research Centre GrowUpWell, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Microbiology, Asthma, and Airways Research Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Philip M Hansbro
- Priority Research Centre for Healthy Lungs, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Microbiology, Asthma, and Airways Research Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Hideo Yagita
- Department of Immunology, Juntendo University, School of Medicine, Tokyo, Japan; and
| | - Paul S Foster
- Priority Research Centre for Healthy Lungs, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Joerg Mattes
- Experimental and Translational Respiratory Medicine Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia; .,Priority Research Centre GrowUpWell, University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia.,Paediatric Respiratory and Sleep Medicine Unit, John Hunter Children's Hospital, Newcastle, Australia
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6
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Nef Is Dispensable for Resistance of Simian Immunodeficiency Virus-Infected Macrophages to CD8+ T Cell Killing. J Virol 2015; 89:10625-36. [PMID: 26269172 DOI: 10.1128/jvi.01699-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/04/2015] [Indexed: 01/29/2023] Open
Abstract
UNLABELLED Simian immunodeficiency virus (SIV)-specific CD8(+) T cells kill SIV-infected CD4(+) T cells in an major histocompatibility complex class I (MHC-I)-dependent manner. However, they are reportedly less efficient at killing SIV-infected macrophages. Since the viral accessory protein Nef has been shown to downregulate MHC-I molecules and enhance cytotoxic T lymphocyte (CTL) evasion in human immunodeficiency virus type 1 (HIV-1)-infected CD4(+) T cells, we examined whether Nef played a role in protecting SIV-infected macrophages from killing by SIV-specific CD8(+) T cells. To explore the role of Nef in CD8(+) T cell evasion, we compared the ability of freshly sorted SIV-specific CD8(+) T cells to readily suppress viral replication or eliminate CD4(+) T cells or monocyte-derived macrophages infected with SIV variants containing wild-type (WT) or mutated nef genes. As expected, SIV-specific CD8(+) T cells suppressed viral replication and eliminated the majority of SIV-infected CD4(+) T cells, and this killing was enhanced in CD4(+) T cells infected with the nef variants. However, macrophages infected with nef variants that disrupt MHC-I downregulation did not promote rapid killing by freshly isolated CD8(+) T cells. These results suggest that mechanisms other than Nef-mediated MHC-I downregulation govern the resistance of SIV-infected macrophages to CD8(+) T cell-mediated killing. This study has implications for viral persistence and suggests that macrophages may afford primate lentiviruses some degree of protection from immune surveillance. IMPORTANCE Myeloid cells are permissive for HIV/SIV replication in vitro and may contribute to viral persistence in vivo. While many studies have been geared to understanding how CD8(+) T cells control viral replication in CD4(+) T cells, the role of these cells in controlling viral replication in macrophages is less clear. Primary, unstimulated CD8(+) T cells insignificantly suppress viral replication or eliminate SIV-infected macrophages. Since the viral Nef protein downregulates MHC-I and provides infected cells some degree of protection from CD8(+) T cell-mediated effector functions, we evaluated whether Nef may be contributing to the resistance of macrophages to CD8(+) T cell suppression. Our results suggest that Nef is not involved in protecting infected macrophages from CD8(+) T cell killing and suggest that other mechanisms are involved in macrophage evasion from CD8 surveillance.
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7
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Dysfunction of mitochondria due to environmental carcinogens in nasopharyngeal carcinoma in the ethnic group of Northeast Indian population. Tumour Biol 2014; 35:6715-24. [PMID: 24711137 DOI: 10.1007/s13277-014-1897-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/26/2014] [Indexed: 10/25/2022] Open
Abstract
Nasopharyngeal carcinoma (NPC) is a rare cancer worldwide, but in India, NPC is uncommon in its subcontinent except in the north-eastern part of the country. NPC is thought to be caused by the combined effects of environmental carcinogens, genetic susceptibility and Epstein-Barr virus (EBV). This is the first study that aimed to examine the selected risk factors, mostly dietary, viral environmental, metabolic gene polymorphisms, mitochondrial DNA (mtDNA) copy number variation and their risk, in subjects who are highly prone to NPC in the ethnic groups of Northeast India, which has included cases, first-degree relatives and controls. The cases and controls were selected from three ethnic groups (Manipuri, Naga and Mizo) of Northeast India with high prevalence of NPC. This case-control family study includes 64 NPC patients, 88 first-degree relatives and 100 controls having no history of cancer. PCR-based detection was done for EBV-latent membrane protein 1 (LMP1) gene and glutathione S-transferase Mu 1 (GSTM1)-glutathione S-transferase theta 1 (GSTT1) polymorphism. A comparative ΔCt method was used for the determination of mtDNA content. An increased risk of 2.00-6.06-folds to NPC was observed with those who intake smoked meat and fish, salted fish and fermented fish; betel nut chewers; tobacco smokers; alcohol drinkers; and those who have kitchen inside the living room, glutathione S-transferase null genotype and EBV infection. The risk of NPC increased in cases with decreased mtDNA copy number (P trend = 0.007). A significant difference between GST null genotypes and EBV infection with mtDNA content was found in the cases (P < 0.0001). The understandings of environment-genetic risk factors and their role in the etiology of NPC are helpful as preventive measures and screening.
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8
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Cleavage of the Junin virus nucleoprotein serves a decoy function to inhibit the induction of apoptosis during infection. J Virol 2012; 87:224-33. [PMID: 23077297 DOI: 10.1128/jvi.01929-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The regulation of apoptosis during infection is an important factor for host survival and, in some cases, also for the virus life cycle. At the same time, mechanisms to prevent the induction of apoptosis have been observed in numerous viral pathogens, but until now the role of apoptosis during arenavirus infection has not been investigated. Junin virus (JUNV) belongs to the New World arenavirus serogroup of the Arenaviridae and is the causative agent of Argentine hemorrhagic fever. We have demonstrated that infection with JUNV in cell culture does not induce apoptosis but leads to cleavage of the nucleoprotein (NP) into discrete products resembling caspase cleavage events. Similar specific NP degradation patterns were also observed in NP-transfected cell lines, and a closer examination of the sequence of NP showed several putative caspase cleavage motifs. Point mutations that abolished these cleavage motifs were consistent with the loss of certain cleavage products. Consistent with these data, further studies showed that treatment with a caspase inhibitor also reduced NP cleavage, indicating that the observed cleavage events were occurring as a result of caspase activity with NP as a substrate. Finally, we showed that expression of NP suppresses the cleavage of caspase 3 in cells treated with an apoptosis activator. Based on these findings, we propose that NP functions as a decoy substrate for caspase cleavage in order to inhibit the induction of apoptosis in JUNV-infected cells.
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Abstract
Mitochondria are involved in a variety of cellular metabolic processes, and their functions are regulated by extrinsic and intrinsic stimuli including viruses. Recent studies have shown that mitochondria play a central role in the primary host defense mechanisms against viral infections, and a number of novel viral and mitochondrial proteins are involved in these processes. Some viral proteins localize in mitochondria and interact with mitochondrial proteins to regulate cellular responses. This review summarizes recent findings on the functions and roles of these molecules as well as mitochondrial responses to viral infections.
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10
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Rowe M, Kelly GL, Bell AI, Rickinson AB. Burkitt's lymphoma: the Rosetta Stone deciphering Epstein-Barr virus biology. Semin Cancer Biol 2009; 19:377-88. [PMID: 19619657 PMCID: PMC3764430 DOI: 10.1016/j.semcancer.2009.07.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 07/10/2009] [Indexed: 02/07/2023]
Abstract
Epstein-Barr virus was originally identified in the tumour cells of a Burkitt's lymphoma, and was the first virus to be associated with the pathogenesis of a human cancer. Studies on the relationship of EBV with Burkitt's lymphoma have revealed important general principles that are relevant to other virus-associated cancers. In addition, the impact of such studies on the knowledge of EBV biology has been enormous. Here, we review some of the key historical observations arising from studies on Burkitt's lymphoma that have informed our understanding of EBV, and we summarise the current hypotheses regarding the role of EBV in the pathogenesis of Burkitt's lymphoma.
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Affiliation(s)
- Martin Rowe
- Institute for Cancer Studies, School of Cancer Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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11
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Shepard BD, Badley AD. The Biology of TRAIL and the Role of TRAIL-Based Therapeutics in Infectious Diseases. ACTA ACUST UNITED AC 2009; 8:87-101. [PMID: 21857885 DOI: 10.2174/187152109787846060] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
TNF-related apoptosis inducing ligand (TRAIL) is a key mediator of the innate immune response to infection. While TRAIL-mediated apoptosis plays an essential role in the clearance of virus-infected cells, its physiologic role also includes immunosurveilance for cancer cells. Therapeutics that induce TRAIL-mediated apoptosis in cancer cells remain a focus of ongoing investigation in clinical trials, and much has been learned from these studies regarding the efficacy and toxicity of these interventions. These data, combined with data from numerous preclinical studies that detail the important and multifaceted role of TRAIL during infection with human immunodeficiency virus and other viruses, suggest that therapeutic exploitation of TRAIL signaling offers a novel and efficacious strategy for the management of infectious diseases.
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Affiliation(s)
- Brett D Shepard
- Mayo Clinic College of Medicine, Division of Infectious Diseases, Rochester, MN, 55905, USA
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12
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Kelly GL, Long HM, Stylianou J, Thomas WA, Leese A, Bell AI, Bornkamm GW, Mautner J, Rickinson AB, Rowe M. An Epstein-Barr virus anti-apoptotic protein constitutively expressed in transformed cells and implicated in burkitt lymphomagenesis: the Wp/BHRF1 link. PLoS Pathog 2009; 5:e1000341. [PMID: 19283066 PMCID: PMC2652661 DOI: 10.1371/journal.ppat.1000341] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 02/12/2009] [Indexed: 02/07/2023] Open
Abstract
Two factors contribute to Burkitt lymphoma (BL) pathogenesis, a chromosomal translocation leading to c-myc oncogene deregulation and infection with Epstein-Barr virus (EBV). Although the virus has B cell growth–transforming ability, this may not relate to its role in BL since many of the transforming proteins are not expressed in the tumor. Mounting evidence supports an alternative role, whereby EBV counteracts the high apoptotic sensitivity inherent to the c-myc–driven growth program. In that regard, a subset of BLs carry virus mutants in a novel form of latent infection that provides unusually strong resistance to apoptosis. Uniquely, these virus mutants use Wp (a viral promoter normally activated early in B cell transformation) and express a broader-than-usual range of latent antigens. Here, using an inducible system to express the candidate antigens, we show that this marked apoptosis resistance is mediated not by one of the extended range of EBNAs seen in Wp-restricted latency but by Wp-driven expression of the viral bcl2 homologue, BHRF1, a protein usually associated with the virus lytic cycle. Interestingly, this Wp/BHRF1 connection is not confined to Wp-restricted BLs but appears integral to normal B cell transformation by EBV. We find that the BHRF1 gene expression recently reported in newly infected B cells is temporally linked to Wp activation and the presence of W/BHRF1-spliced transcripts. Furthermore, just as Wp activity is never completely eclipsed in in vitro–transformed lines, low-level BHRF1 transcripts remain detectable in these cells long-term. Most importantly, recognition by BHRF1-specific T cells confirms that such lines continue to express the protein independently of any lytic cycle entry. This work therefore provides the first evidence that BHRF1, the EBV bcl2 homologue, is constitutively expressed as a latent protein in growth-transformed cells in vitro and, in the context of Wp-restricted BL, may contribute to virus-associated lymphomagenesis in vivo. Cancer almost always develops through the cumulative effects of several independent changes in the target cell. For certain tumors, one step in the chain involves infection of the cell with a particular type of virus. The best example is Burkitt lymphoma (BL), a tumor of B lymphocytes which develops through the combined action of a genetic accident leading to uncontrolled expression of the c-myc oncogene and infection with a common herpesvirus, the Epstein-Barr virus (EBV). Recent evidence suggests that, although latent EBV infection can itself drive B cell growth, the virus plays a different role in the context of BL, namely to counteract the naturally poor survival ability of c-myc–expressing cells while leaving their c-myc–driven growth intact. Here we show that EBV achieves this by unexpectedly switching on a viral protein that was thought never to be seen in latent infection; this viral protein resembles one of the cell's own key survival proteins called bcl2. Furthermore, the work has led us to realise that this virally encoded bcl2-like protein is not only important in the context of BL but, contrary to conventional wisdom, is actually part of EBV's natural strategy for B cell growth transformation.
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Affiliation(s)
- Gemma L. Kelly
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Heather M. Long
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Julianna Stylianou
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Wendy A. Thomas
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Alison Leese
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Andrew I. Bell
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Georg W. Bornkamm
- GSF-Institut fur Klinische Molekularbiologie und Tumorgenetik GSF-Forschungszentrum fur Umwelt und Gesundheit, Munich, Germany
| | - Josef Mautner
- Munich University of Technology, Children's Hospital, Munich, Germany
| | - Alan B. Rickinson
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail:
| | - Martin Rowe
- Cancer Research UK Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham, United Kingdom
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Juanola S, Vives J, Milián E, Prats E, Cairó JJ, Gòdia F. Expression of BHRF1 improves survival of murine hybridoma cultures in batch and continuous modes. Appl Microbiol Biotechnol 2009; 83:43-57. [PMID: 19139878 DOI: 10.1007/s00253-008-1820-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 12/03/2008] [Accepted: 12/08/2008] [Indexed: 12/20/2022]
Abstract
Cell death by apoptosis limits growth and productivity in most animal cell cultures. It is therefore desirable to define genetic interventions to generate robust cell lines with superior performance in bioreactors, either by increasing specific productivity, life-span of the cultures or both. In this context, forced expression of BHRF1, an Epstein-Barr virus-encoded early protein with structural and functional homology with the anti-apoptotic protein Bcl-2, effectively protected hybridomas in culture and delayed cell death under conditions of glutamine starvation. In the present study, we explored the potential application of BHRF1 expression in hybridomas for long-term apoptosis protection under different biotechnological process designs (batch and continuous) and compared it to strategies based on Bcl-2 overexpression. Our results confirmed that long-term maintenance of the anti-apoptotic effect of BHRF1 can be obtained using bicistronic configurations conferring enhanced protection compared to Bcl-2, even in the absence of selective pressure. Such protective effect of BHRF1 is demonstrated both in batch and continuous culture. Moreover, a further analysis at high cell densities in semi-continuous perfusion cultures indicated that the mechanism of action of BHRF1 involves cell cycle arrest in G0-G1 state and this is translated in lower numbers of dead cells.
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Affiliation(s)
- Sandra Juanola
- Departament d'Enginyeria Química, Escola Tècnica Superior d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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14
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Swingler S, Mann AM, Zhou J, Swingler C, Stevenson M. Apoptotic killing of HIV-1-infected macrophages is subverted by the viral envelope glycoprotein. PLoS Pathog 2007; 3:1281-90. [PMID: 17907802 PMCID: PMC2323301 DOI: 10.1371/journal.ppat.0030134] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 07/26/2007] [Indexed: 11/18/2022] Open
Abstract
Viruses have evolved strategies to protect infected cells from apoptotic clearance. We present evidence that HIV-1 possesses a mechanism to protect infected macrophages from the apoptotic effects of the death ligand TRAIL (tumor necrosis factor–related apoptosis-inducing ligand). In HIV-1–infected macrophages, the viral envelope protein induced macrophage colony-stimulating factor (M-CSF). This pro-survival cytokine downregulated the TRAIL receptor TRAIL-R1/DR4 and upregulated the anti-apoptotic genes Bfl-1 and Mcl-1. Inhibition of M-CSF activity or silencing of Bfl-1 and Mcl-1 rendered infected macrophages highly susceptible to TRAIL. The anti-cancer agent Imatinib inhibited M-CSF receptor activation and restored the apoptotic sensitivity of HIV-1–infected macrophages, suggesting a novel strategy to curtail viral persistence in the macrophage reservoir. Much of our understanding regarding mechanisms of HIV-1 persistence has been derived from studies with lymphocytes. However, mechanisms governing persistent infection of macrophages are less well understood. We investigated whether HIV-1 modulates macrophage function in a way that promotes their persist infection. We focused on a cytokine called macrophage colony-stimulating factor (M-CSF), because this pro-survival factor is induced upon infection by HIV-1. We found that the viral envelope gene was necessary for M-CSF induction of macrophages. M-CSF upregulated anti-apoptotic genes in macrophages and restricted the expression of the death receptor (tumor necrosis factor–related apoptosis-inducing ligand [TRAIL]-R1). As a consequence, HIV-1–infected macrophages were resistant to the apoptotic effects of TRAIL. If M-CSF was blocked by antibody or if the anti-apoptotic genes were silenced by RNA interference, the apoptotic sensitivity of HIV-1–infected macrophages was restored. Also, the anti-cancer drug Imatinib, which impairs activation of the M-CSF receptor, promoted the death of HIV-1–infected macrophages but not of uninfected macrophages. We believe that HIV-1 regulates M-CSF to extend macrophage survival and promote viral persistence in the host. Agents that interfere with M-CSF signaling, such as Imatinib, warrant further examination for activity against macrophage reservoirs in vivo.
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Affiliation(s)
- Simon Swingler
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Angela M Mann
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jin Zhou
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Catherine Swingler
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Mario Stevenson
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
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15
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Abstract
Epstein-Barr virus (EBV) infection is linked to approximately 90% of B-cell lymphomas associated with posttransplant lymphoproliferative disease (PTLD), a serious complication for immunosuppressed transplant recipients. In this paper, we review the myriad ways by which EBV can inadvertently drive the genesis and persistence of B-cell lymphomas, particularly when the antiviral immune response is compromised. Probing the basic mechanisms by which EBV infection proceeds and contributes to malignancy in such cases will hopefully improve our understanding and treatment of PTLD and other EBV-associated malignancies.
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Affiliation(s)
- Andrew L Snow
- Program in Immunology, Stanford University School of Medicine, Stanford, California, USA
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16
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Li LY, Liu MY, Shih HM, Tsai CH, Chen JY. Human cellular protein VRK2 interacts specifically with Epstein-Barr virus BHRF1, a homologue of Bcl-2, and enhances cell survival. J Gen Virol 2006; 87:2869-2878. [PMID: 16963744 DOI: 10.1099/vir.0.81953-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BHRF1, an early gene product of Epstein-Barr virus (EBV), is structurally and functionally homologous to Bcl-2, a cellular anti-apoptotic protein. BHRF1 has been shown to protect cells from apoptosis induced by numerous external stimuli. Nasopharyngeal carcinoma is an epithelial cancer associated closely with EBV infection. Specific proteins that might interact with and modulate the BHRF1 anti-apoptotic activity in normal epithelial cells are of interest. Therefore, a cDNA library derived from normal human foreskin keratinocytes was screened by the yeast two-hybrid system and a cellular gene encoding human vaccinia virus B1R kinase-related kinase 2 (VRK2) was isolated. Interaction between the cellular VRK2 and viral BHRF1 proteins was further demonstrated by glutathione S-transferase pull-down assays, confocal laser-scanning microscopy and co-immunoprecipitation. Analyses of VRK2-deletion mutants revealed that a 108 aa fragment at the C terminus was important for VRK2 to interact with BHRF1. For BHRF1, aa 1-18 and 89-142 were crucial in interacting with VRK2 and these two regions are counterparts of Bcl-2 homology domains 4 and 1. Overexpressed VRK2 alone showed a modest effect in anti-apoptosis and appeared to enhance cell survival in the presence of BHRF1. However, this enhancement was not observed when VRK2 was co-expressed with Bcl-2. The results indicate that human VRK2 interacts specifically with EBV BHRF1 and that the interaction is involved in protecting cells from apoptosis.
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Affiliation(s)
- Long-Yuan Li
- Institute of Cancer Research, National Health Research Institutes, Taipei 114, Taiwan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Mei-Ying Liu
- Department of General Education, National Taipei College of Nursing, Taipei 112, Taiwan
- Institute of Cancer Research, National Health Research Institutes, Taipei 114, Taiwan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Hsiu-Ming Shih
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Taipei 115, Taiwan
| | - Ching-Hwa Tsai
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Jen-Yang Chen
- Institute of Cancer Research, National Health Research Institutes, Taipei 114, Taiwan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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17
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Zhang Y, Ohyashiki JH, Takaku T, Shimizu N, Ohyashiki K. Transcriptional profiling of Epstein-Barr virus (EBV) genes and host cellular genes in nasal NK/T-cell lymphoma and chronic active EBV infection. Br J Cancer 2006; 94:599-608. [PMID: 16449999 PMCID: PMC2361178 DOI: 10.1038/sj.bjc.6602968] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nasal NK/T-cell lymphoma is an aggressive subtype of non-Hodgkin lymphoma (NHL) that is closely associated with Epstein–Barr virus (EBV). The clonal expansion of EBV-infected NK or T cells is also seen in patients with chronic active EBV (CAEBV) infection, suggesting that two diseases might share a partially similar mechanism by which EBV affects host cellular gene expression. To understand the pathogenesis of EBV-associated NK/T-cell lymphoproliferative disorders (LPD) and design new therapies, we employed a novel EBV DNA microarray to compare patterns of EBV expression in six cell lines established from EBV-associated NK/T-cell LPD. We found that expression of BZLF1, which encodes the immediate-early gene product Zta, was expressed in SNK/T cells and the expression levels were preferentially high in cell lines from CAEBV infection. We also analyzsd the gene expression patterns of host cellular genes using a human oligonucleotide DNA microarray. We identified a subset of pathogenically and clinically relevant host cellular genes, including TNFRSF10D, CDK2, HSPCA, IL12A as a common molecular biological properties of EBV-associated NK/T-cell LPD and a subset of genes, such as PDCD4 as a putative contributor for disease progression. This study describes a novel approach from the aspects of viral and host gene expression, which could identify novel therapeutic targets in EBV-associated NK/T-cell LPD.
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Affiliation(s)
- Y Zhang
- First Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan
| | - J H Ohyashiki
- Intractable Immune System Disease Research Center, Tokyo Medical University, 6-7-1, Nishi-shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
- ntractable Immune System Disease Research Center, Tokyo Medical University, 6-7-1, Nishi-shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan. E-mail:
| | - T Takaku
- First Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan
| | - N Shimizu
- Department of Virology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - K Ohyashiki
- First Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan
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18
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Abstract
In response to invasion by microbial pathogens, host defense mechanisms get activated by both the innate and adaptive arms of the immune responses. TNF (tumor necrosis factor) is a potent proinflammatory cytokine expressed by activated macrophages and lymphocytes that induces diverse cellular responses that can vary from apoptosis to the expression of genes involved in both early inflammatory and acquired immune responses. A wide spectrum of microbes has acquired elegant mechanisms to overcome or deflect the host responses mediated by TNF. For example, modulatory proteins encoded by multiple families of viruses can block TNF and TNF-mediated responses at multiple levels, such as the inhibition of the TNF ligand or its receptors, or by modulating key transduction molecules of the TNF signaling pathway. Bacteria, on the other hand, tend to modify TNF-mediated responses specifically by regulating components of the TNF signaling pathway. Investigation of these diverse strategies employed by viral and bacterial pathogens has significantly advanced our understanding of both host TNF responses and microbial pathogenesis. This review summarizes the diverse microbial strategies to regulate TNF and how such insights into TNF modulation could benefit the treatment of inflammatory or autoimmune diseases.
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19
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Vernon SD, Whistler T, Cameron B, Hickie IB, Reeves WC, Lloyd A. Preliminary evidence of mitochondrial dysfunction associated with post-infective fatigue after acute infection with Epstein Barr virus. BMC Infect Dis 2006; 6:15. [PMID: 16448567 PMCID: PMC1373655 DOI: 10.1186/1471-2334-6-15] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 01/31/2006] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Acute infectious diseases are typically accompanied by non-specific symptoms including fever, malaise, irritability and somnolence that usually resolve on recovery. However, in some individuals these symptoms persist in what is commonly termed post-infective fatigue. The objective of this pilot study was to determine the gene expression correlates of post-infective fatigue following acute Epstein Barr virus (EBV) infection. METHODS We followed 5 people with acute mononucleosis who developed post-infective fatigue of more than 6 months duration and 5 HLA-matched control subjects who recovered within 3 months. Subjects had peripheral blood mononuclear cell (PBMC) samples collected at varying time points including at diagnosis, then every 2 weeks for 3 months, then every 3 months for a year. Total RNA was extracted from the PBMC samples and hybridized to microarrays spotted with 3,800 oligonucleotides. RESULTS Those who developed post-infective fatigue had gene expression profiles indicative of an altered host response during acute mononucleosis compared to those who recovered uneventfully. Several genes including ISG20 (interferon stimulated gene), DNAJB2 (DnaJ [Hsp40] homolog and CD99), CDK8 (cyclin-dependent kinase 8), E2F2 (E2F transcription factor 2), CDK8 (cyclin-dependent kinase 8), and ACTN2 (actinin, alpha 2), known to be regulated during EBV infection, were differentially expressed in post-infective fatigue cases. Several of the differentially expressed genes affect mitochondrial functions including fatty acid metabolism and the cell cycle. CONCLUSION These preliminary data provide insights into alterations in gene transcripts associated with the varied clinical outcomes from acute infectious mononucleosis.
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Affiliation(s)
- Suzanne D Vernon
- Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, Georgia 30333, USA
| | - Toni Whistler
- Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, Georgia 30333, USA
| | | | - Ian B Hickie
- Brain and Mind Research Institute, University of Sydney, New South Wales, Sydney 2006, Australia
| | - William C Reeves
- Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, Georgia 30333, USA
| | - Andrew Lloyd
- University of New South Wales, Sydney 2052, Australia
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20
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Boya P, Pauleau AL, Poncet D, Gonzalez-Polo RA, Zamzami N, Kroemer G. Viral proteins targeting mitochondria: controlling cell death. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1659:178-89. [PMID: 15576050 DOI: 10.1016/j.bbabio.2004.08.007] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Revised: 07/20/2004] [Accepted: 08/16/2004] [Indexed: 01/21/2023]
Abstract
Mitochondrial membrane permeabilization (MMP) is a critical step regulating apoptosis. Viruses have evolved multiple strategies to modulate apoptosis for their own benefit. Thus, many viruses code for proteins that act on mitochondria and control apoptosis of infected cells. Viral proapoptotic proteins translocate to mitochondrial membranes and induce MMP, which is often accompanied by mitochondrial swelling and fragmentation. From a structural point of view, all the viral proapoptotic proteins discovered so far contain amphipathic alpha-helices that are necessary for the proapoptotic effects and seem to have pore-forming properties, as it has been shown for Vpr from human immunodeficiency virus-1 (HIV-1) and HBx from hepatitis B virus (HBV). In contrast, antiapoptotic viral proteins (e.g., M11L from myxoma virus, F1L from vaccinia virus and BHRF1 from Epstein-Barr virus) contain mitochondrial targeting sequences (MTS) in their C-terminus that are homologous to tail-anchoring domains. These domains are similar to those present in many proteins of the Bcl-2 family and are responsible for inserting the protein in the outer mitochondrial membrane leaving the N-terminus of the protein facing the cytosol. The antiapoptotic proteins K7 and K15 from avian encephalomyelitis virus (AEV) and viral mitochondria inhibitor of apoptosis (vMIA) from cytomegalovirus are capable of binding host-specific apoptosis-modulatory proteins such as Bax, Bcl-2, activated caspase 3, CAML, CIDE-B and HAX. In conclusion, viruses modulate apoptosis at the mitochondrial level by multiple different strategies.
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Affiliation(s)
- Patricia Boya
- Centre National de la Recherche Scientifique, UMR 8125, Institut Gustave Roussy, Pavillon de Recherche 1, 39 rue Camille-Desmoulins, F-94805 Villejuif, France
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21
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D'Agostino DM, Bernardi P, Chieco-Bianchi L, Ciminale V. Mitochondria as Functional Targets of Proteins Coded by Human Tumor Viruses. Adv Cancer Res 2005; 94:87-142. [PMID: 16096000 DOI: 10.1016/s0065-230x(05)94003-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Molecular analyses of tumor virus-host cell interactions have provided key insights into the genes and pathways involved in neoplastic transformation. Recent studies have revealed that the human tumor viruses Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV), human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), and human T-cell leukemia virus type 1 (HTLV-1) express proteins that are targeted to mitochondria. The list of these viral proteins includes BCL-2 homologues (BHRF1 of EBV; KSBCL-2 of KSHV), an inhibitor of apoptosis (IAP) resembling Survivin (KSHV K7), proteins that alter mitochondrial ion permeability and/or membrane potential (HBV HBx, HPV E[wedge]14, HCV p7, and HTLV-1 p13(II)), and K15 of KSHV, a protein with undefined function. Consistent with the central role of mitochondria in energy production, cell death, calcium homeostasis, and redox balance, experimental evidence indicates that these proteins have profound effects on host cell physiology. In particular, the viral BCL-2 homologues BHRF1 and KSBCL-2 inhibit apoptosis triggered by a variety of stimuli. HBx, p7, E1[wedge]4, and p13(II) exert powerful effects on mitochondria either directly due to their channel-forming activity or indirectly through interactions with endogenous channels. Further investigation of these proteins and their interactions with mitochondria will provide important insights into the mechanisms of viral replication and tumorigenesis and could aid in the discovery of new targets for anti-tumor therapy.
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Affiliation(s)
- Donna M D'Agostino
- Department of Oncology and Surgical Sciences, University of Padova, Padova 35128, Italy
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22
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Esfandiarei M, Luo H, Yanagawa B, Suarez A, Dabiri D, Zhang J, McManus BM. Protein kinase B/Akt regulates coxsackievirus B3 replication through a mechanism which is not caspase dependent. J Virol 2004; 78:4289-98. [PMID: 15047842 PMCID: PMC374262 DOI: 10.1128/jvi.78.8.4289-4298.2004] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The role of signaling pathways including the mitogen-activated protein kinases (MAPKs) and phosphatidylinositol 3-kinase (PI3K) during viral infection has gained much recent attention. Our laboratory reported on an important regulatory role for extracellular signal-regulated kinases (ERK1/2), subfamily members of the MAPKs, during coxsackievirus B3 (CVB3) infection. However, the role of the PI3K pathway in CVB3 infection has not been well characterized. CVB3 is the most common known viral infectant of heart muscle that directly injures and kills infected cardiac myocytes during the myocarditic process. In the present study, we investigated the role of protein kinase B (PKB) (also known as Akt), a general downstream mediator of survival signals through the PI3K cascade, in regulating CVB3 replication and virus-induced apoptosis in a well-established HeLa cell model. We have demonstrated that CVB3 infection leads to phosphorylation of PKB/Akt on both Ser-473 and Thr-308 residues through a PI3K-dependent mechanism. Transfection of HeLa cells with a dominant negative mutant of Akt1 or pretreatment of wild-type HeLa cells with the specific PI3K inhibitor LY294002 significantly suppresses viral RNA expression, as reflected in diminished viral capsid protein expression and viral release. Dominant negative Akt1 and LY294002 also increase apoptosis in infected cells, which can be reversed by addition of the general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk). Interestingly, blocking of apoptosis by zVAD.fmk does not reverse the viral RNA translation blockade, indicating that the inhibitory effect of dominant negative Akt1 on viral protein expression is not caspase dependent. In addition, we showed that the attachment of virus to its receptor-coreceptor complex is not sufficient for PKB/Akt activation and that postentry viral replication is required for Akt phosphorylation. Taken together, these data illustrate a new and imperative role for Akt in CVB3 infection in HeLa cells and show that the PI3K/Akt signaling is beneficial to CVB3 replication.
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Affiliation(s)
- Mitra Esfandiarei
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Department of Pathology and Laboratory Medicine, St. Paul's Hospital/Providence Health Care-University of British Columbia, Vancouver, Canada
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23
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Polster BM, Pevsner J, Hardwick JM. Viral Bcl-2 homologs and their role in virus replication and associated diseases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1644:211-27. [PMID: 14996505 DOI: 10.1016/j.bbamcr.2003.11.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2003] [Accepted: 11/04/2003] [Indexed: 01/26/2023]
Abstract
Cellular Bcl-2 family proteins regulate a critical step in the mammalian programmed cell death pathway by modulating mitochondrial permeability and function. Bcl-2 family proteins are also encoded by several large DNA viruses, including all known gamma herpesviruses, adenoviruses, and several other unrelated viruses. Viral Bcl-2 proteins can prevent cell death but often escape cellular regulatory mechanisms that govern their cellular counterparts. By evading the "altruistic" suicide of infected cells, viruses can ensure replication and propagation in the infected host, but sometimes in surprising ways. Many human cancers and other disorders are associated with viruses that encode Bcl-2 homologs. Here we consider the available mechanistic data for viral compared to cellular Bcl-2 protein function along with relevance to the virus life cycle and human disease states.
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Affiliation(s)
- Brian M Polster
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
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24
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Huang Q, Petros AM, Virgin HW, Fesik SW, Olejniczak ET. Solution structure of the BHRF1 protein from Epstein-Barr virus, a homolog of human Bcl-2. J Mol Biol 2003; 332:1123-30. [PMID: 14499614 DOI: 10.1016/j.jmb.2003.08.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The three-dimensional structure of BHRF1, the Bcl-2 homolog from Epstein-Barr virus (EBV), has been determined by NMR spectroscopy. Although the overall structure is similar to other Bcl-2 family members, there are important structural differences. Unlike some of the other Bcl-2 family members, BHRF1 does not contain the prominent hydrophobic groove that mediates binding to pro-apoptotic family members. In addition, in contrast to the anti-apoptotic Bcl-2 proteins, BHRF1 does not bind tightly to peptides derived from the pro-apoptotic proteins Bak, Bax, Bik, and Bad. The lack of an exposed, pre-formed binding groove in BHRF1 and the lack of significant binding to peptides derived from pro-apoptotic family members that bind to other anti-apoptotic family members, suggest that the mechanism of the BHRF1 anti-apoptotic activity does not parallel that of cellular Bcl-x(L) or Bcl-2.
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Affiliation(s)
- Qiulong Huang
- Global Pharmaceutical Discovery Division, Abbott Laboratories, 100 Abbott Park Road, R46Y AP 10, Abbott Park, IL 0064-6098, USA
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25
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Tada-Oikawa S, Hiraku Y, Kawanishi M, Kawanishi S. Mechanism for generation of hydrogen peroxide and change of mitochondrial membrane potential during rotenone-induced apoptosis. Life Sci 2003; 73:3277-88. [PMID: 14561532 DOI: 10.1016/j.lfs.2003.06.013] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Rotenone, an inhibitor of NADH dehydrogenase complex, is a naturally occurring insecticide, which is capable of inducing apoptosis. Rotenone-induced apoptosis is considered to contribute to its anticancer effect and the etiology of Parkinson's disease (PD). We demonstrated that rotenone induced internucleosomal DNA fragmentation, DNA ladder formation, in human cultured cells, HL-60 (promyelocytic leukemia) and BJAB cells (B-cell lymphoma). Flow cytometry showed that rotenone induced H2O2 generation, followed by significant changes in the mitochondrial membrane potential (DeltaPsim). Caspase-3 activity increased in HL-60 cells in a time-dependent manner. These apoptotic events were delayed in HP100 cells, an H2O2-resistant clone of HL-60, confirming the involvement of H2O2 in apoptosis. Expression of anti-apoptotic protein, Bcl-2, in BJAB cells drastically inhibited DeltaPsim change and DNA ladder formation but not H2O2 generation, confirming the participation of mitochondrial dysfunction in apoptosis. NAD(P)H oxidase inhibitors prevented H2O2 generation and DNA ladder formation. These results suggest that rotenone induces O2(-)-derived H2O2 generation through inhibition of NADH dehydrogenase complex and/or activation of NAD(P)H oxidase, and H2O2 generation causes the disruption of mitochondrial membrane in rotenone-induced apoptosis.
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Affiliation(s)
- Saeko Tada-Oikawa
- Department of Environmental and Molecular Medicine, Mie University School of Medicine, 2-174 Edobashi, -Tsu-shi, Mie, 514-8507, Japan
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26
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Abstract
All members of the gamma-herpesvirus family encode genes capable of inhibiting apoptosis. Inhibition of a variety of types of apoptotic stimuli have been demonstrated for specific viral genes, including pathways induced by the immune system as well as internal pathways. Virally encoded genes inhibit the activation of caspase-8 by the TNF receptor and Fas; activate NF-kappaB to increase expression of antiapoptotic genes; inhibit interferon response; bind to p53, thereby blocking p53 dependent apoptosis; and interact with other pro- and antiapoptotic cellular genes. All gamma-herpesviruses also express viral homologues of cellular antiapoptotic genes, including one or two Bcl-2 homologues. The human gamma-herpesviruses encode genes that can inhibit apoptosis during both latent and lytic infection. During latent phase infection inhibition of apoptosis is likely important for persistence of the gamma-herpesviruses in the face of immune attack, but it is also required for maintenance of infected cells in culture. During lytic replication the virus inhibits apoptosis to prevent cell death before viral replication and spread occurs.
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Affiliation(s)
- Michael Lagunoff
- Department of Microbiology, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA.
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27
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Marshall NA, Vickers MA, Barker RN. Regulatory T cells secreting IL-10 dominate the immune response to EBV latent membrane protein 1. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:6183-9. [PMID: 12794149 DOI: 10.4049/jimmunol.170.12.6183] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Viruses exploit a number of strategies to evade immune recognition. In this study, we describe a novel mechanism by which EBV, rather than avoiding detection, subverts the immune response by stimulating regulatory T cells that secrete IL-10. Human PBMC from all EBV-seropositive, but not -seronegative, donors responded to both purified latent membrane protein 1 and the corresponding immunodominant peptides with high levels of IL-10 secretion by CD4(+) T cells. These IL-10 responses, characteristic of T regulatory 1 cells, inhibited T cell proliferation and IFN-gamma secretion induced by both mitogen and recall Ag. It was confirmed that the inhibition was IL-10 dependent by the use of neutralizing Ab. The deviation of the immune response toward suppression is likely to be important in maintaining latency and EBV-associated tumors.
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Affiliation(s)
- Neil A Marshall
- Department of Medicine and Therapeutics, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
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