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Epstein-Barr virus nuclear protein EBNA3C residues critical for maintaining lymphoblastoid cell growth. Proc Natl Acad Sci U S A 2009; 106:4419-24. [PMID: 19237563 DOI: 10.1073/pnas.0813134106] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) is essential for efficient conversion of primary human B lymphocytes to lymphoblastoid cell lines (LCLs) and for continued LCL growth. We used a transcomplementation assay in the context of LCLs transformed by an EBV with a conditional EBNA3C to identify the EBNA3C amino acids (aa) necessary for maintaining LCL growth. Surprisingly, we found that most EBNA3C aa were essential for continued LCL growth. Only EBNA3C mutants deleted for residues within aa 507-515, 516-620, 637-675, or 676-727 maintained full LCL growth, and EBNA3C mutants deleted for residues within aa 728-732 or 910-992 maintained slow LCL growth. In contrast, EBNA3C lacking aa 180-231, which mediate RBP-Jkappa association and are necessary for EBNA3C abrogation of EBNA2-induced transcription through RBP-Jkappa, could not support LCL growth. Furthermore, 2 EBNA3C alanine substitution mutants within aa 180-231, which were wild-type (wt) in abrogating EBNA2-mediated transcription through RBP-Jkappa, maintained LCL growth, and 2 alanine substitution mutants within aa 180-231, which were null in abrogating EBNA2-mediated transcription through RBP-Jkappa, did not maintain LCL growth. This indicates that EBNA3C regulation of transcription through RBP-Jkappa is critical to maintaining LCL growth. Several other EBNA3C functions also are critical for LCL growth, because EBNA3C mutants deleted for residues within aa 130-159, 251-506, or 733-909 were wt in abrogating transcription through RBP-Jkappa and expression level, but did not maintain LCL growth.
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103
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Tsimbouri P, Al-Sheikh Y, Drotar ME, Cushley W, Wilson JB. Epstein-Barr virus nuclear antigen-1 renders lymphocytes responsive to IL-2 but not IL-15 for survival. J Gen Virol 2009; 89:2821-2832. [PMID: 18931080 DOI: 10.1099/vir.0.83296-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Epstein-Barr virus nuclear antigen-1 (EBNA-1) is the only latent protein expressed in all virus-associated tumours. It plays a critical role in viral propagation and in the replication, episomal maintenance and partitioning of the viral genome. However, its tumorigenic potential is debated. We have previously shown that lymphocytes from a tumour-prone, EBNA-1-expressing, transgenic mouse line show increased responsiveness to interleukin-2 (IL-2). It was important to determine whether this property was unique to the transgenic line or whether it is a general consequence of EBNA-1 expression in B cells. In order to distinguish between these possibilities, explanted lymphocytes from two independent transgenic mouse lines were examined. The lymphocytes from both lines showed enhanced proliferation rates compared with controls. The transgenic lymphocytes survived for extended periods in culture, dependent on the dose of IL-2, while IL-15 (the receptor of which shares the beta and gamma chain components of the IL-2 receptor) induced little effect. In accordance with this, transgenic B cells showed enhanced induction of expression of the IL-2 receptor alpha chain (CD25), which modulates affinity for the ligand. As this phenotype is evident in lymphocytes from mice of both lines, it is necessarily independent of any transgene insertion site effects and may be attributed to EBNA-1 expression. Furthermore, 10/12 tumour-bearing transgenic mice had elevated IL-2 levels in serum and 4/6 tumours were CD25 positive. IL-2 is normally produced by activated T cells in vivo; thus, chronic immune activation or modulation could elicit this unique mode of virus-infected cell survival.
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Affiliation(s)
- Penelope Tsimbouri
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, UK
| | - Yazeed Al-Sheikh
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, UK
| | - Mark E Drotar
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, UK
| | - William Cushley
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, UK
| | - Joanna B Wilson
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, UK
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104
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The Epstein-Barr virus nuclear antigen-1 promotes genomic instability via induction of reactive oxygen species. Proc Natl Acad Sci U S A 2009; 106:2313-8. [PMID: 19139406 DOI: 10.1073/pnas.0810619106] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The Epstein-Barr virus (EBV) nuclear antigen (EBNA)-1 is the only viral protein expressed in all EBV-carrying malignancies, but its contribution to oncogenesis has remained enigmatic. We show that EBNA-1 induces chromosomal aberrations, DNA double-strand breaks, and engagement of the DNA damage response (DDR). These signs of genomic instability are associated with the production of reactive oxygen species (ROS) and are reversed by antioxidants. The catalytic subunit of the leukocyte NADPH oxidase, NOX2/gp91(phox), is transcriptionally activated in EBNA-1-expressing cells, whereas inactivation of the enzyme by chemical inhibitors or RNAi halts ROS production and DDR. These findings highlight a novel function of EBNA-1 and a possible mechanism by which expression of this viral protein could contribute to malignant transformation and tumor progression.
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105
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Kumar P, Murakami M, Kaul R, Saha A, Cai Q, Robertson ES. Deregulation of the cell cycle machinery by Epstein-Barr virus nuclear antigen 3C. Future Virol 2009; 4:79-91. [PMID: 25635182 DOI: 10.2217/17460794.4.1.79] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus associated with a large number of lymphoid and epithelial malignancies. As a successful pathogen it has co-evolved with its human host for millions of years. EBV has the unique ability to establish life-long latent infection in primary human B lymphocytes. During latent infection, a small subset of viral proteins is expressed. These proteins are essential for maintenance of the EBV genome as well as the deregulation of various signaling pathways that facilitate the proliferation and survival of the infected cells. Epstein-Barr nuclear antigen (EBNA)3C is one of the latent proteins shown to be essential for transformation of primary human B lymphocytes in vitro. EBNA3C primarily functions as a transcriptional regulator by interacting with a number of well known cellular and viral transcriptional factors. We have recently identified several binding partners for EBNA3C including proteins that regulate cell cycle and chromatin remodeling. We are actively engaged in discerning the biological significance of these interactions. This review summarizes our current understanding of how EBNA3C usurps cellular pathways that promote B-cell transformation.
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Affiliation(s)
- Pankaj Kumar
- Department of Microbiology & The Tumor Virology Program of the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, PA, USA
| | - Masanao Murakami
- Department of Microbiology & The Tumor Virology Program of the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, PA, USA
| | - Rajeev Kaul
- Department of Microbiology & The Tumor Virology Program of the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, PA, USA
| | - Abhik Saha
- Department of Microbiology & The Tumor Virology Program of the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, PA, USA
| | - Qiliang Cai
- Department of Microbiology & The Tumor Virology Program of the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, PA, USA
| | - Erle S Robertson
- Department of Microbiology & The Tumor Virology Program of the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, 201E Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104, USA, Tel.: +1 215 746 0114
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106
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Gargouri B, Van Pelt J, El Feki AEF, Attia H, Lassoued S. Induction of Epstein-Barr virus (EBV) lytic cycle in vitro causes oxidative stress in lymphoblastoid B cell lines. Mol Cell Biochem 2008; 324:55-63. [PMID: 19082543 DOI: 10.1007/s11010-008-9984-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 12/01/2008] [Indexed: 12/11/2022]
Abstract
Here, we investigated the effect of induction of the Epstein-Barr virus (EBV) viral lytic cycle on the oxidant/antioxidant balance in three lymphoblastoid cell lines: B95-8, Raji, and LCL C1. The induction of the EBV lytic cycle was done by a non-stressing dose of 12-0-tetradecanoylphorbol-13-acetate (8 nM). Oxidative stress was assessed by measuring malondialdehyde as a parameter of lipid peroxidation, the levels of glutathione, and the activities of three antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase). After 48 h (peak of lytic cycle), a significant decrease in superoxide dismutase activity was observed in B95-8, Raji, and LCL C1 cells (P < 0.05). In addition, in B95-8 cells also a significant decrease of catalase activity was detected (P < 0.05). The glutathione peroxidase activity and the glutathione level were not significantly modified by the induction in any of the cell lines. We found a significant rise in malondialdehyde levels in B95-8, Raji, and LCL C1 cells after the induction of the lytic cycle compared to controls (P < 0.05). In conclusion, induction of EBV lytic cycle in lymphoblastoid cells causes increased oxidative stress in the host cells within 48 h, a process that could be involved in malignant transformations.
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Affiliation(s)
- Bochra Gargouri
- Unité de Biotechnologie et Pathologies, Institut Supérieur de Biotechnologie de Sfax, Sfax, Tunisia.
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107
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Delecluse HJ, Feederle R, Behrends U, Mautner J. Contribution of viral recombinants to the study of the immune response against the Epstein-Barr virus. Semin Cancer Biol 2008; 18:409-15. [DOI: 10.1016/j.semcancer.2008.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Accepted: 09/23/2008] [Indexed: 12/26/2022]
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108
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Abstract
Burkitt's lymphoma is a rapidly fatal tumor if untreated, but it is curable with intensive polychemotherapy. Unfortunately, the toxicities reported for its treatment in adults are poorly tolerated. Novel therapies aimed at specific molecular targets might prove to be less toxic. A better knowledge of the mechanisms involved in the pathogenesis of Burkitt's lymphoma would facilitate the identification of such targets. This review explores the current knowledge on the alterations found in the three main Burkitt's lymphoma variants.
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Affiliation(s)
- M R Campanero
- Departamento de Biología del Cáncer, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.
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109
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Restricted expression of Epstein-Barr virus latent genes in murine B cells derived from embryonic stem cells. PLoS One 2008; 3:e1996. [PMID: 18414672 PMCID: PMC2289878 DOI: 10.1371/journal.pone.0001996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 03/10/2008] [Indexed: 12/15/2022] Open
Abstract
Background Several human malignancies are associated with Epstein-Barr virus (EBV) and more than 95% of the adult human population carries this virus lifelong. EBV efficiently infects human B cells and persists in this cellular compartment latently. EBV-infected B cells become activated and growth transformed, express a characteristic set of viral latent genes, and acquire the status of proliferating lymphoblastoid cell lines in vitro. Because EBV infects only primate cells, it has not been possible to establish a model of infection in immunocompetent rodents. Such a model would be most desirable in order to study EBV's pathogenesis and latency in a suitable and amenable host. Methodology/Principal Findings We stably introduced recombinant EBV genomes into mouse embryonic stem cells and induced their differentiation to B cells in vitro to develop the desired model. In vitro differentiated murine B cells maintained the EBV genomes but expression of viral genes was restricted to the latent membrane proteins (LMPs). In contrast to human B cells, EBV's nuclear antigens (EBNAs) were not expressed detectably and growth transformed murine B cells did not arise in vitro. Aberrant splicing and premature termination of EBNA mRNAs most likely prevented the expression of EBNA genes required for B-cell transformation. Conclusions/Significance Our findings indicate that fundamental differences in gene regulation between mouse and man might block the route towards a tractable murine model for EBV.
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110
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Abstract
To test whether transgenic Epstein-Barr virus nuclear antigen 1 (EBNA1) expression in C57BL/6 mouse lymphocytes causes lymphoma, EBNA1 expressed in three FVB lineages at two or three times the level of latent infection was crossed up to six successive times into C57BL/6J mice. After five or six crosses, 14/36, (38%) EBNA1 transgenic mice, 11/31 (36%) littermate EBNA1-negative controls, and 9/25 (36%) inbred C57BL/6J mice housed in the same facility had lymphoma. These data indicate that EBNA1 does not significantly increase lymphoma prevalence in C57BL/6J mice.
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111
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Dheekollu J, Deng Z, Wiedmer A, Weitzman MD, Lieberman PM. A role for MRE11, NBS1, and recombination junctions in replication and stable maintenance of EBV episomes. PLoS One 2007; 2:e1257. [PMID: 18040525 PMCID: PMC2094660 DOI: 10.1371/journal.pone.0001257] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/07/2007] [Indexed: 11/18/2022] Open
Abstract
Recombination-like structures formed at origins of DNA replication may contribute to replication fidelity, sister chromatid cohesion, chromosome segregation, and overall genome stability. The Epstein-Barr Virus (EBV) origin of plasmid replication (OriP) provides episomal genome stability through a poorly understood mechanism. We show here that recombinational repair proteins MRE11 and NBS1 are recruited to the Dyad Symmetry (DS) region of OriP in a TRF2- and cell cycle-dependent manner. Depletion of MRE11 or NBS1 by siRNA inhibits OriP replication and destabilized viral episomes. OriP plasmid maintenance was defective in MRE11 and NBS1 hypomorphic fibroblast cell lines and only integrated, non-episomal forms of EBV were detected in a lympoblastoid cell line derived from an NBS1-mutated individual. Two-dimensional agarose gel analysis of OriP DNA revealed that recombination-like structures resembling Holliday-junctions form at OriP in mid S phase. MRE11 and NBS1 association with DS coincided with replication fork pausing and origin activation, which preceded the formation of recombination structures. We propose that NBS1 and MRE11 promote replication-associated recombination junctions essential for EBV episomal maintenance and genome stability.
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Affiliation(s)
- Jayaraju Dheekollu
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Zhong Deng
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Andreas Wiedmer
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | | | - Paul M. Lieberman
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * To whom correspondence should be addressed. E-mail:
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112
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The LMP1 oncogene of EBV activates PERK and the unfolded protein response to drive its own synthesis. Blood 2007; 111:2280-9. [PMID: 18042799 DOI: 10.1182/blood-2007-07-100032] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The oncogene latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) without a ligand drives proliferation of EBV-infected B cells. Its levels vary in cells of clonal populations by more than 100-fold, which leads to multiple distinct activities of the oncogene. At intermediate levels it drives proliferation, and at high levels it inhibits general protein synthesis by inducing phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha). We have found that LMP1 activates PERK to induce phosphorylation of eIF2alpha, which upregulates activating transcription factor 4 (ATF4) expression. ATF4, in turn, transactivates LMP1's own promoter. LMP1 activates not only PERK but also inositol requiring kinase 1 (IRE1) and ATF6, 3 pathways of the unfolded protein response (UPR). Increasing expression levels of LMP1 induced a dose-dependent increase in IRE1 activity, as measured by its "splicing" of XBP-1. These infected B cells secrete immunoglobins independent of the levels of LMP1, indicating that only a threshold level of XBP-1 is required for the secretion. These findings indicate that LMP1's activation of the UPR is a normal event in a continuum of LMP1's expression that leads both to stimulatory and inhibitory functions and regulates the physiology of EBV-infected B cells in multiple, unexpected modes.
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113
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The latent membrane protein 1 oncogene modifies B-cell physiology by regulating autophagy. Oncogene 2007; 27:2833-42. [PMID: 18037963 DOI: 10.1038/sj.onc.1210946] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Epstein-Barr virus (EBV) is a herpes virus that is associated with several human cancers. Infection of B cells by EBV leads to their induction and maintenance of proliferation and requires the oncogene, latent membrane protein 1 (LMP1). LMP1 signals in a ligand-independent manner and is expressed at widely different levels in cells of a single clone. It is this unusual distribution that allows LMP1 to stimulate multiple, distinct pathways. Average levels of LMP1 induce proliferation while high levels induce cytostasis and inhibition of protein synthesis. These inhibitory pathways are induced by the six transmembrane domains of LMP1. We uncovered a novel function encoded by transmembrane domains 3-6 of LMP1; they induce autophagy in a dose-dependent manner and thus, modify the physiology of their host. Cells that express low levels of LMP1 display early stages of autophagy, autophagosomes; those that express high levels of this oncogene display late stages of autophagy, autolysosomes. Inhibition of autophagy in EBV-positive cells leads to an accumulation of LMP1 and a decreased ability to form colonies. These results indicate that LMP1's induction of autophagy contributes to its own regulation and that of its host cell.
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114
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Chiu YF, Tung CP, Lee YH, Wang WH, Li C, Hung JY, Wang CY, Kawaguchi Y, Liu ST. A comprehensive library of mutations of Epstein Barr virus. J Gen Virol 2007; 88:2463-2472. [PMID: 17698655 DOI: 10.1099/vir.0.82881-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A mutant library of 249 mutants with mutations that span the entire Epstein-Barr virus (EBV) genome was generated by transposition with EZ : : TN <KAN-2> and insertion with an apramycin resistance gene by a PCR-targeting method. This study also demonstrates the feasibility of generating deletions and site-specific mutations in the BRLF1 promoter on the EBV genome to determine the regions in the promoter that are crucial to transcription. Analysing BZLF1 and BRLF1 mutants by microarray analysis revealed that these two genes regulate the transcription of EBV lytic genes differently. A BZLF1 mutation affects global expression of EBV lytic genes; almost no lytic gene is expressed by the mutant after lytic induction. However, although a BRLF1 mutant still transcribes most lytic genes, the expression of these lytic genes is inefficient. Furthermore, this study shows that the proximal Zta-response element in the BRLF1 promoter is crucial to BRLF1 transcription from the EBV genome, despite the fact that another work demonstrated that this site was unimportant in transient transfection analysis. Furthermore, mutants with a mutation in BDLF1 and BORF1 cannot assemble viral capsids. Results of this study demonstrate the usefulness of a comprehensive mutant library in genetic analyses of EBV.
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Affiliation(s)
- Ya-Fang Chiu
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang Gung University, Taoyuan 333, Taiwan
| | - Chao-Ping Tung
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang Gung University, Taoyuan 333, Taiwan
| | - Yu-Hisu Lee
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang Gung University, Taoyuan 333, Taiwan
| | - Wen-Hung Wang
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang Gung University, Taoyuan 333, Taiwan
| | - Ching Li
- Department of Applied Microbiology, National Chiayi University, Chiayi City 600, Taiwan
| | - Jia-Yan Hung
- Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung 402, Taiwan
| | - Chen-Yu Wang
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang Gung University, Taoyuan 333, Taiwan
| | - Yasushi Kawaguchi
- Division of Viral Infection, Department of Infectious Disease Control, International Research Center for Infections Diseases, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-Ku, Tokyo 108-8639, Japan
| | - Shih-Tung Liu
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang Gung University, Taoyuan 333, Taiwan
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115
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Wood VHJ, O'Neil JD, Wei W, Stewart SE, Dawson CW, Young LS. Epstein-Barr virus-encoded EBNA1 regulates cellular gene transcription and modulates the STAT1 and TGFbeta signaling pathways. Oncogene 2007; 26:4135-47. [PMID: 17486072 DOI: 10.1038/sj.onc.1210496] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Epstein-Barr virus (EBV)-encoded EBNA1 protein is expressed in all virus-associated tumors where it plays an essential role in the maintenance, replication and transcription of the EBV genome. Transcriptional profiling of EBNA1-expressing carcinoma cells demonstrated that EBNA1 also influences the expression of a range of cellular genes including those involved in translation, transcription and cell signaling. Of particular interest was the ability of EBNA1 to enhance expression of STAT1 and sensitize cells to interferon-induced STAT1 activation with resultant enhancement of major histocompatibility complex expression. A negative effect of EBNA1 on the expression of TGFbeta1-responsive betaig-h3 and PAI-1 genes was confirmed at the protein level in EBV-infected carcinoma cells. This effect resulted from the ability of EBNA1 to repress TGFbeta1-induced transcription via a reduction in the interaction of SMAD2 with SMAD4. More detailed analysis revealed that EBNA1 induces a lower steady-state level of SMAD2 protein as a consequence of increased protein turnover. These data show that EBNA1 can influence cellular gene transcription resulting in effects that may contribute to the development of EBV-associated tumors.
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Affiliation(s)
- V H J Wood
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Edgbaston, Birmingham, UK
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116
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Lünemann JD, Kamradt T, Martin R, Münz C. Epstein-barr virus: environmental trigger of multiple sclerosis? J Virol 2007; 81:6777-84. [PMID: 17459939 PMCID: PMC1933281 DOI: 10.1128/jvi.00153-07] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
MESH Headings
- Animals
- Antibodies, Viral/immunology
- Antibody Formation
- Arthritis, Rheumatoid/epidemiology
- Arthritis, Rheumatoid/etiology
- Arthritis, Rheumatoid/genetics
- Arthritis, Rheumatoid/immunology
- B-Lymphocytes/immunology
- B-Lymphocytes/virology
- Chromosomes, Human, Pair 6/genetics
- Chromosomes, Human, Pair 6/immunology
- Environment
- Epstein-Barr Virus Infections/complications
- Epstein-Barr Virus Infections/epidemiology
- Epstein-Barr Virus Infections/genetics
- Epstein-Barr Virus Infections/immunology
- Epstein-Barr Virus Nuclear Antigens/genetics
- Epstein-Barr Virus Nuclear Antigens/immunology
- HLA-DQ Antigens/genetics
- HLA-DQ Antigens/immunology
- HLA-DR Antigens/genetics
- HLA-DR Antigens/immunology
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/immunology
- Humans
- Immunity, Cellular
- Immunoglobulin G/immunology
- Immunologic Memory
- Longitudinal Studies
- Lupus Erythematosus, Systemic/epidemiology
- Lupus Erythematosus, Systemic/etiology
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/immunology
- Multiple Sclerosis/epidemiology
- Multiple Sclerosis/etiology
- Multiple Sclerosis/genetics
- Multiple Sclerosis/immunology
- Prevalence
- Risk Factors
- Skin Diseases/epidemiology
- Skin Diseases/etiology
- Skin Diseases/genetics
- Skin Diseases/immunology
- T-Lymphocytes/immunology
- United States/epidemiology
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Affiliation(s)
- Jan D Lünemann
- Laboratory of Viral Immunobiology, Christopher H. Browne Center for Immunology and Immune Diseases, The Rockefeller University, Box 390, 1230 York Avenue, New York, NY 10021-6399, USA
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117
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Yamashita Y, Tsurumi T, Mori N, Kiyono T. Immortalization of Epstein-Barr virus-negative human B lymphocytes with minimal chromosomal instability. Pathol Int 2006; 56:659-67. [PMID: 17040288 DOI: 10.1111/j.1440-1827.2006.02026.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The genes required for immortalization of human B cells infected by Epstein-Barr virus are multiple, and the precise mechanism of this process remains to be elucidated. In the present study HPV16 E6 and E7 were retrovirally transduced into human primary B cells stimulated by CD40-CD40L interaction, thereby establishing an Epstein-Barr virus negative immortalized human B cell line, which continued to proliferate for more than 2 years (100 population doublings). The established cell line had a high telomerase activity from the beginning of the culture period, and no shortening of the telomere length was observed. A chromosomal analysis revealed that a large portion of the HPV16E6E7 transduced cells had retained a normal karyotype. Similar to human epithelial cells, human B lymphocytes seem to require two steps for immortalization, namely, the inactivation of the p16/Rb pathway and the activation of telomerase, the latter that can be induced by the CD40-CD40L interaction. Furthermore, using this system, it is possible to analyze the role of individual genes in human B lymphocyte immortalization without the influence of a pre-existing Epstein-Barr virus genome.
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Affiliation(s)
- Yoriko Yamashita
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
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118
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Manzini S, Vargiolu A, Stehle IM, Bacci ML, Cerrito MG, Giovannoni R, Zannoni A, Bianco MR, Forni M, Donini P, Papa M, Lipps HJ, Lavitrano M. Genetically modified pigs produced with a nonviral episomal vector. Proc Natl Acad Sci U S A 2006; 103:17672-7. [PMID: 17101993 PMCID: PMC1635978 DOI: 10.1073/pnas.0604938103] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Genetic modification of cells and animals is an invaluable tool for biotechnology and biomedicine. Currently, integrating vectors are used for this purpose. These vectors, however, may lead to insertional mutagenesis and variable transgene expression and can undergo silencing. Scaffold/matrix attachment region-based vectors are nonviral expression systems that replicate autonomously in mammalian cells, thereby making possible safe and reliable genetic modification of higher eukaryotic cells and organisms. In this study, genetically modified pig fetuses were produced with the scaffold/matrix attachment region-based vector pEPI, delivered to embryos by the sperm-mediated gene transfer method. The pEPI vector was detected in 12 of 18 fetuses in the different tissues analyzed and was shown to be retained as an episome. The reporter gene encoded by the pEPI vector was expressed in 9 of 12 genetically modified fetuses. In positive animals, all tissues analyzed expressed the reporter gene; moreover in these tissues, the positive cells were on the average 79%. The high percentage of EGFP-expressing cells and the absence of mosaicism have important implications for biotechnological and biomedical applications. These results are an important step forward in animal transgenesis and can provide the basis for the future development of germ-line gene therapy.
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Affiliation(s)
- Stefano Manzini
- *Department of Surgical Sciences, University of Milano-Bicocca, 20052 Milan,Italy
| | - Alessia Vargiolu
- *Department of Surgical Sciences, University of Milano-Bicocca, 20052 Milan,Italy
| | - Isa M Stehle
- Institute of Cell Biology, Witten/Herdecke University, 58448 Witten, Germany
| | - Maria Laura Bacci
- Department of Veterinary Morphophysiology and Animal Production, University of Bologna, 40064 Bologna, Italy
| | - Maria Grazia Cerrito
- *Department of Surgical Sciences, University of Milano-Bicocca, 20052 Milan,Italy
| | - Roberto Giovannoni
- *Department of Surgical Sciences, University of Milano-Bicocca, 20052 Milan,Italy
| | - Augusta Zannoni
- Department of Veterinary Morphophysiology and Animal Production, University of Bologna, 40064 Bologna, Italy
| | - Maria Rosaria Bianco
- Centro Regionale di Competenza Applicazioni Tecnologico-Industriali di Biomolecole e Biosistemi-BioTekNet-Seconda Università di Napoli, 80138 Naples, Italy; and
| | - Monica Forni
- Department of Veterinary Morphophysiology and Animal Production, University of Bologna, 40064 Bologna, Italy
| | - Pierluigi Donini
- Department of Cellular and Developmental Biology, La Sapienza University, 00185 Rome, Italy
| | - Michele Papa
- Centro Regionale di Competenza Applicazioni Tecnologico-Industriali di Biomolecole e Biosistemi-BioTekNet-Seconda Università di Napoli, 80138 Naples, Italy; and
| | - Hans J Lipps
- Institute of Cell Biology, Witten/Herdecke University, 58448 Witten, Germany
| | - Marialuisa Lavitrano
- *Department of Surgical Sciences, University of Milano-Bicocca, 20052 Milan,Italy
- To whom correspondence should be addressed. E-mail:
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119
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Cesarman E, Mesri EA. Kaposi sarcoma-associated herpesvirus and other viruses in human lymphomagenesis. Curr Top Microbiol Immunol 2006; 312:263-87. [PMID: 17089801 DOI: 10.1007/978-3-540-34344-8_10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV), also called human herpesvirus 8 (HHV-8), is associated with a specific subset of lymphoproliferative disorders. These include two main categories. The first is primary effusion lymphomas and related solid variants. The second is multicentric Castleman disease, from which KSHV-positive plasmablastic lymphomas can arise. KSHV contributes to lymphomagenesis by subverting the host cell molecular signaling machinery to deregulate cell growth and survival. KSHV expresses a selected set of genes in the lymphoma cells, encoding viral proteins that play important roles in KSHV lymphomagenesis. Deregulation of the NF-kappaB pathway is an important strategy used by KSHV to promote lymphoma cell survival, and the viral protein vFLIP is essential for this process. Two other viruses that are well documented to be causally associated with lymphoid neoplasia in humans are Epstein-Barr virus (EBV/HHV-4) and human T-cell lymphotropic virus (HTLV-1). Both of these are similar to KSHV in their use of viral proteins to promote cell survival by deregulating the NF-kappaB pathway. Here we review the basic information and recent developments that have contributed to our knowledge of lymphomas caused by KSHV and other viruses. The understanding of the mechanisms of viral lymphomagenesis should lead to the identification of novel therapeutic targets and to the development of rationally designed therapies.
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Affiliation(s)
- E Cesarman
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10021, USA.
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120
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Heller KN, Upshaw J, Seyoum B, Zebroski H, Münz C. Distinct memory CD4+ T-cell subsets mediate immune recognition of Epstein Barr virus nuclear antigen 1 in healthy virus carriers. Blood 2006; 109:1138-46. [PMID: 16985171 PMCID: PMC1785143 DOI: 10.1182/blood-2006-05-023663] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
CD4+ T cells, specific for transforming latent infection with the Epstein Barr virus (EBV), consistently recognize the nuclear antigen 1 of EBV (EBNA1). EBNA1-specific effector CD4+ T cells are primarily T-helper 1 (TH1) polarized. Here we show that most healthy EBV carriers have such IFN-secreting EBNA1-specific CD4+ T cells at a frequency of 0.03% of circulating CD4+ T cells. In addition, healthy carriers have a large pool of CD4+ T cells that proliferated in response to EBNA1 and consisted of distinct memory-cell subsets. Despite continuous antigen presence due to persistent EBV infection, half of the proliferating EBNA1-specific CD4+ T cells belonged to the central-memory compartment (TCM). The remaining EBNA1-specific CD4+ T cells displayed an effector-memory phenotype (TEM), of which a minority rapidly secreted IFN upon stimulation with EBNA1. Based on chemokine receptor analysis, all EBNA1-specific TCM CD4+ T cells were TH1 committed. Our results suggest that protective immune control of chronic infections, like EBV, includes a substantial reservoir of TCM CD4+ TH1 precursors, which continuously fuels TH1-polarized effector cells.
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Affiliation(s)
- Kevin N Heller
- Laboratory of Viral Immunobiology, Christopher H. Browne Center for Immunology and Immune Diseases, The Rockefeller University, New York, NY 10021, USA
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121
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Altmann M, Pich D, Ruiss R, Wang J, Sugden B, Hammerschmidt W. Transcriptional activation by EBV nuclear antigen 1 is essential for the expression of EBV's transforming genes. Proc Natl Acad Sci U S A 2006; 103:14188-93. [PMID: 16966603 PMCID: PMC1599932 DOI: 10.1073/pnas.0605985103] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
EBV is a paradigm for human tumor viruses because, although it infects most people benignly, it also can cause a variety of cancers. Both in vivo and in vitro, EBV infects B lymphocytes in G0, induces them to become blasts, and can maintain their proliferation in cell culture or in vivo as tumors. How EBV succeeds in these contrasting cellular environments in expressing its genes that control the host has not been explained. We have genetically dissected the EBV nuclear antigen 1 (EBNA1) gene that is required for replication of the viral genome, to elucidate its possible role in the transcription of viral genes. Strikingly, EBNA1 is essential to drive transcription of EBV's transforming genes after infection of primary B lymphocytes.
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Affiliation(s)
- Markus Altmann
- Department of Gene Vectors, GSF-National Research Center for Environment and Health, Marchioninistrasse 25, 81377 München, Germany; and
| | - Dagmar Pich
- Department of Gene Vectors, GSF-National Research Center for Environment and Health, Marchioninistrasse 25, 81377 München, Germany; and
| | - Romana Ruiss
- Department of Gene Vectors, GSF-National Research Center for Environment and Health, Marchioninistrasse 25, 81377 München, Germany; and
| | - Jindong Wang
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, WI 53706
| | - Bill Sugden
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, WI 53706
| | - Wolfgang Hammerschmidt
- Department of Gene Vectors, GSF-National Research Center for Environment and Health, Marchioninistrasse 25, 81377 München, Germany; and
- To whom correspondence should be addressed. E-mail:
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122
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Affiliation(s)
- Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Division of Hematology-Oncology, Department of Medicine, Weill Medical College of Cornell University and The New York Presbyterian Hospital, New York, NY, USA
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123
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Imai S, Kuroda M, Yamashita R, Ishiura Y. [Therapeutic inhibition of Epstein-Barr virus-associated tumor cell growth by dominant-negative EBNA1]. Uirusu 2006; 55:239-49. [PMID: 16557009 DOI: 10.2222/jsv.55.239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1), a latent viral protein consistently expressed in infected proliferating cells, is essentially required in trans to maintain EBV episomes in cells. Thus EBNA1 will be an appropriate target for specific molecular therapy against EBV-associated cancers. We constructed a mutant (mt) EBNA1 lacking the N-terminal-half, relative to wild-type (wt) EBNA1, and demonstrated that it exerted dominant-negative effects on maintenance of the viral episome from cells regardless of viral latency or tissue origin thereby leading to significant suppression of naturally EBV-harboring Burkitt's lymphoma cell growth in vitro and in vivo. Our mutant can act as dominant-negative (dn) EBNA1 and will afford an additional therapeutic strategy specifically targeting EBV-associated malignancies. The similar approach can be applicable to exploit novel remedial protocols against uncontrollable diseases caused by other persistently-infected viruses. In addition, dnEBNA1 may also provide a useful analytical tool for the possible oncogenic function(s) of wtEBNA1.
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Affiliation(s)
- Shosuke Imai
- Department of Molecular Microbiology and Infections, Kochi Medical School, Nankoku, Kochi, Japan.
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124
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Kitamura R, Sekimoto T, Ito S, Harada S, Yamagata H, Masai H, Yoneda Y, Yanagi K. Nuclear import of Epstein-Barr virus nuclear antigen 1 mediated by NPI-1 (Importin alpha5) is up- and down-regulated by phosphorylation of the nuclear localization signal for which Lys379 and Arg380 are essential. J Virol 2006; 80:1979-91. [PMID: 16439554 PMCID: PMC1367128 DOI: 10.1128/jvi.80.4.1979-1991.2006] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is essential for replication of episomal EBV DNAs and maintenance of latency. Multifunctional EBNA-1 is phosphorylated, but the significance of EBNA-1 phosphorylation is not known. Here, we examined the effects on nuclear translocation of Ser phosphorylation of the EBNA-1 nuclear localization signal (NLS) sequence, 379Lys-Arg-Pro-Arg-Ser-Pro-Ser-Ser386. We found that Lys379Ala and Arg380Ala substitutions greatly reduced nuclear transport and steady-state levels of green fluorescent protein (GFP)-EBNA1, whereas Pro381Ala, Arg382Ala, Pro384Ala, and Glu378Ala substitutions did not. Microinjection of modified EBNA-1 NLS peptide-inserted proteins and NLS peptides cross-linked to bovine serum albumin (BSA) showed that Ala substitution for three NLS Ser residues reduced the efficiency of nuclear import. Similar microinjection analyses demonstrated that phosphorylation of Ser385 accelerated the rate of nuclear import, but phosphorylation of Ser383 and Ser386 reduced it. However, transfection analyses of GFP-EBNA1 mutants with the Ser-to-Ala substitution causing reduced nuclear import efficiency did not result in a decrease in the nuclear accumulation level of EBNA-1. The results suggest dynamic nuclear transport control of phosphorylated EBNA-1 proteins, although the nuclear localization level of EBNA-1 that binds to cellular chromosomes and chromatin seems unchanged. The karyopherin alpha NPI-1 (importin alpha5), a nuclear import adaptor, bound more strongly to Ser385-phosphorylated NLS than to any other phosphorylated or nonphosphorylated forms. Rch1 (importin alpha1) bound only weakly and Qip1 (importin alpha3) did not bind to the Ser385-phosphorylated NLS. These findings suggest that the amino-terminal 379Lys-Arg380 is essential for the EBNA-1 NLS and that Ser385 phosphorylation up-regulates nuclear transport efficiency of EBNA-1 by increasing its binding affinity to NPI-1, while phosphorylation of Ser386 and Ser383 down-regulates it.
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Affiliation(s)
- Ryo Kitamura
- AIDS Research Center, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo 162-8640, Japan
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125
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Hong GK, Kumar P, Wang L, Damania B, Gulley ML, Delecluse HJ, Polverini PJ, Kenney SC. Epstein-Barr virus lytic infection is required for efficient production of the angiogenesis factor vascular endothelial growth factor in lymphoblastoid cell lines. J Virol 2006; 79:13984-92. [PMID: 16254334 PMCID: PMC1280197 DOI: 10.1128/jvi.79.22.13984-13992.2005] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Although Epstein-Barr virus (EBV)-associated malignancies are primarily composed of cells with one of the latent forms of EBV infection, a small subset of tumor cells containing the lytic form of infection is often observed. Whether the rare lytically infected tumor cells contribute to the growth of the latently infected tumor cells is unclear. Here we have investigated whether the lytically infected subset of early-passage lymphoblastoid cell lines (LCLs) could potentially contribute to tumor growth through the production of angiogenesis factors. We demonstrate that supernatants from early-passage LCLs infected with BZLF1-deleted virus (Z-KO LCLs) are highly impaired in promoting endothelial cell tube formation in vitro compared to wild-type (WT) LCL supernatants. Furthermore, expression of the BZLF1 gene product in trans in Z-KO LCLs restored angiogenic capacity. The supernatants of Z-KO LCLs, as well as supernatants from LCLs derived with a BRLF1-deleted virus (R-KO LCLs), contained much less vascular endothelial growth factor (VEGF) in comparison to WT LCLs. BZLF1 gene expression in Z-KO LCLs restored the VEGF level in the supernatant. However, the cellular level of VEGF mRNA was similar in Z-KO, R-KO, and WT LCLs, suggesting that lytic infection may enhance VEGF translation or secretion. Interestingly, a portion of the vasculature in LCL tumors in SCID mice was derived from the human LCLs. These results suggest that lytically infected cells may contribute to the growth of EBV-associated malignancies by enhancing angiogenesis. In addition, as VEGF is a pleiotropic factor with effects other than angiogenesis, lytically induced VEGF secretion may potentially contribute to viral pathogenesis.
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Affiliation(s)
- Gregory K Hong
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
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126
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Hong GK, Gulley ML, Feng WH, Delecluse HJ, Holley-Guthrie E, Kenney SC. Epstein-Barr virus lytic infection contributes to lymphoproliferative disease in a SCID mouse model. J Virol 2006; 79:13993-4003. [PMID: 16254335 PMCID: PMC1280209 DOI: 10.1128/jvi.79.22.13993-14003.2005] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Most Epstein-Barr virus (EBV)-positive tumor cells contain one of the latent forms of viral infection. The role of lytic viral gene expression in EBV-associated malignancies is unknown. Here we show that EBV mutants that cannot undergo lytic viral replication are defective in promoting EBV-mediated lymphoproliferative disease (LPD). Early-passage lymphoblastoid cell lines (LCLs) derived from EBV mutants with a deletion of either viral immediate-early gene grew similarly to wild-type (WT) virus LCLs in vitro but were deficient in producing LPD when inoculated into SCID mice. Restoration of lytic EBV gene expression enhanced growth in SCID mice. Acyclovir, which prevents lytic viral replication but not expression of early lytic viral genes, did not inhibit the growth of WT LCLs in SCID mice. Early-passage LCLs derived from the lytic-defective viruses had substantially decreased expression of the cytokine interleukin-6 (IL-6), and restoration of lytic gene expression reversed this defect. Expression of cellular IL-10 and viral IL-10 was also diminished in lytic-defective LCLs. These results suggest that lytic EBV gene expression contributes to EBV-associated lymphoproliferative disease, potentially through induction of paracrine B-cell growth factors.
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Affiliation(s)
- Gregory K Hong
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
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127
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Kenney S. Theodore E. Woodward Award: development of novel, EBV-targeted therapies for EBV-positive tumors. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2006; 117:55-74. [PMID: 18528464 PMCID: PMC1500921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The near universal presence of EBV in certain tumors suggests that new EBV-based therapies could be developed for these malignancies. We have explored one EBV-based therapy that involves the purposeful induction of lytic EBV infection in tumors. Induction of lytic EBV infection in tumors activates expression of EBV-encoded kinases that convert the prodrug, ganciclovir, to its active cytotoxic form. In mouse models for EBV-positive tumors, the combination of lytic-inducing chemotherapy and ganciclovir is much more effective than either agent alone for treating tumors. Another potential EBV-based target is the cellular protein, CD70. EBV-positive tumors commonly express CD70, while CD70 expression in normal cells is restricted to a few highly activated B cells and T cells. Anti-CD70 monoclonal antibody inhibits the growth of CD70-positive (but not CD70-negative) Burkitt's lymphomas in SCID mice. Finally, while completely lytic EBV infection is clearly incompatible with tumor cell growth, we recently discovered that small numbers of lytically-infected cells actually promote the growth of EBV-immortalized lymphocytes in SCID mice, through the release of paracrine growth factors as well as angiogenic factors. Thus, agents that prevent the earliest stage of lytic EBV infection (such as fatty acid synthase inhibitors), rather than the later stage of viral replication, might also be useful in the treatment of early-stage EBV-positive tumors.
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Affiliation(s)
- Shannon Kenney
- Department of Medicine and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, CB #7295, Chapel Hill, North Carolina 27599, USA.
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128
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Altmann M, Hammerschmidt W. Epstein-Barr virus provides a new paradigm: a requirement for the immediate inhibition of apoptosis. PLoS Biol 2005; 3:e404. [PMID: 16277553 PMCID: PMC1283332 DOI: 10.1371/journal.pbio.0030404] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Accepted: 09/27/2005] [Indexed: 11/19/2022] Open
Abstract
DNA viruses such as herpesviruses are known to encode homologs of cellular antiapoptotic viral Bcl-2 proteins (vBcl-2s), which protect the virus from apoptosis in its host cell during virus synthesis. Epstein-Barr virus (EBV), a human tumor virus and a prominent member of γ-herpesviruses, infects primary resting B lymphocytes to establish a latent infection and yield proliferating, growth-transformed B cells in vitro. In these cells, 11 viral genes that contribute to cellular transformation are consistently expressed. EBV also encodes two vBcl-2 genes whose roles are unclear. Here we show that the genetic inactivation of both vBcl-2 genes disabled EBV's ability to transform primary resting B lymphocytes. Primary B cells infected with a vBcl-2-negative virus did not enter the cell cycle and died of immediate apoptosis. Apoptosis was abrogated in infected cells in which vBcl-2 genes were maximally expressed within the first 24 h postinfection. During latent infection, however, the expression of vBcl-2 genes became undetectable. Thus, both vBcl-2 homologs are essential for initial cellular transformation but become dispensable once a latent infection is established. Because long-lived, latently infected memory B cells and EBV-associated B-cell lymphomas are derived from EBV-infected proapoptotic germinal center B cells, we conclude that vBcl-2 genes are essential for the initial evasion of apoptosis in cells in vivo in which the virus establishes a latent infection or causes cellular transformation or both. The transformation of resting B-lymphocytes by a human tumor virus is shown to require vBcl-2 genes, which abrogate host cell apoptosis. These genes are not required once latent infection is established.
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Affiliation(s)
- Markus Altmann
- 1Department of Gene Vectors, GSF-National Research Center for Environment and Health, München, Germany
| | - Wolfgang Hammerschmidt
- 1Department of Gene Vectors, GSF-National Research Center for Environment and Health, München, Germany
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129
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Mochida A, Gotoh E, Senpuku H, Harada S, Kitamura R, Takahashi T, Yanagi K. Telomere size and telomerase activity in Epstein-Barr virus (EBV)-positive and EBV-negative Burkitt’s lymphoma cell lines. Arch Virol 2005; 150:2139-50. [PMID: 15986178 DOI: 10.1007/s00705-005-0557-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Accepted: 03/30/2005] [Indexed: 11/26/2022]
Abstract
The telomere repeat lengths of BL cell lines were quantified by measuring terminal restriction fragment (TRF). Epstein-Barr virus (EBV)-positive Namalwa, Raji, and EB-3 cell lines have long telomeres, i.e. TRFs 10-19 kbp, whereas the Daudi cell line, producing a transformation-defective EBV mutant, has TRFs approximately 2.2 kbp. EBV-negative BJAB and DG75 cell lines have short TRFs 3.9-5.4 kbp, shorter than the approximately 12 kbp TRFs in PBLs. Telomerase activities of these BL cell lines are similar. TRFs of non-BL lymphoma cell lines are 2.3-5.5 kbp. Fluorescent in situ hybridization (FISH) studies of these cell lines showed remarkable heterogeneity of telomere size in chromosomes in the same BL cell. These results suggest that EBV-positive and EBV-negative BL cell lines have experienced various telomere dynamics.
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Affiliation(s)
- A Mochida
- Herpesvirus Laboratory, Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
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130
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Deng Z, Atanasiu C, Zhao K, Marmorstein R, Sbodio JI, Chi NW, Lieberman PM. Inhibition of Epstein-Barr virus OriP function by tankyrase, a telomere-associated poly-ADP ribose polymerase that binds and modifies EBNA1. J Virol 2005; 79:4640-50. [PMID: 15795250 PMCID: PMC1069541 DOI: 10.1128/jvi.79.8.4640-4650.2005] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Tankyrase (TNKS) is a telomere-associated poly-ADP ribose polymerase (PARP) that has been implicated along with several telomere repeat binding factors in the regulation of Epstein-Barr virus origin of plasmid replication (OriP). We now show that TNKS1 can bind to the family of repeats (FR) and dyad symmetry regions of OriP by using a chromatin immunoprecipitation assay and DNA affinity purification. TNKS1 and TNKS2 bound to EBNA1 in coimmunoprecipitation experiments with transfected cell lysates and with purified recombinant proteins in vitro. Two RXXPDG-like TNKS-interacting motifs in the EBNA1 amino-terminal domain mediated binding with the ankyrin repeat domain of TNKS. Mutations of both motifs at EBNA1 G81 and G425 abrogated TNKS binding and enhanced EBNA1-dependent replication of OriP. Small hairpin RNA targeted knock-down of TNKS1 enhanced OriP-dependent DNA replication. Overexpression of TNKS1 or TNKS2 inhibited OriP-dependent DNA replication, while a PARP-inactive form of TNKS2 (M1045V) was compromised for this inhibition. We show that EBNA1 is subject to PAR modification in vivo and to TNKS1-mediated PAR modification in vitro. These results indicate that TNKS proteins can interact directly with the EBNA1 protein, associate with the FR region of OriP in vivo, and inhibit OriP replication in a PARP-dependent manner.
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Affiliation(s)
- Zhong Deng
- The Wistar Institute, Philadelphia, PA 19104, USA
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131
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Saridakis V, Sheng Y, Sarkari F, Holowaty MN, Shire K, Nguyen T, Zhang RG, Liao J, Lee W, Edwards AM, Arrowsmith CH, Frappier L. Structure of the p53 binding domain of HAUSP/USP7 bound to Epstein-Barr nuclear antigen 1 implications for EBV-mediated immortalization. Mol Cell 2005; 18:25-36. [PMID: 15808506 DOI: 10.1016/j.molcel.2005.02.029] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2004] [Revised: 11/23/2004] [Accepted: 02/23/2005] [Indexed: 12/12/2022]
Abstract
USP7/HAUSP is a key regulator of p53 and Mdm2 and is targeted by the Epstein-Barr nuclear antigen 1 (EBNA1) protein of Epstein-Barr virus (EBV). We have determined the crystal structure of the p53 binding domain of USP7 alone and bound to an EBNA1 peptide. This domain is an eight-stranded beta sandwich similar to the TRAF-C domains of TNF-receptor associated factors, although the mode of peptide binding differs significantly from previously observed TRAF-peptide interactions in the sequence (DPGEGPS) and the conformation of the bound peptide. NMR chemical shift analyses of USP7 bound by EBNA1 and p53 indicated that p53 binds the same pocket as EBNA1 but makes less extensive contacts with USP7. Functional studies indicated that EBNA1 binding to USP7 can protect cells from apoptotic challenge by lowering p53 levels. The data provide a structural and conceptual framework for understanding how EBNA1 might contribute to the survival of Epstein-Barr virus-infected cells.
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Affiliation(s)
- Vivian Saridakis
- Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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132
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Chen A, Divisconte M, Jiang X, Quink C, Wang F. Epstein-Barr virus with the latent infection nuclear antigen 3B completely deleted is still competent for B-cell growth transformation in vitro. J Virol 2005; 79:4506-9. [PMID: 15767450 PMCID: PMC1061580 DOI: 10.1128/jvi.79.7.4506-4509.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Epstein-Barr virus (EBV) nuclear antigen 3B (EBNA-3B) is considered nonessential for EBV-mediated B-cell growth transformation in vitro based on three virus isolates with EBNA-3B mutations. Two of these isolates could potentially express truncated EBNA-3B products, and, similarly, we now show that the third isolate, IB4, has a point mutation and in-frame deletion of 263 amino acids. In order to test whether a virus with EBNA-3B completely deleted can immortalize B-cell growth, we first cloned the EBV genome as a bacterial artificial chromosome (BAC) and showed that the BAC-derived virus was B-cell immortalization competent. Deletion of the entire EBNA-3B open reading frame from the EBV BAC had no adverse impact on growth of EBV-immortalized B cells, providing formal proof that EBNA-3B is not essential for EBV-mediated B-cell growth transformation in vitro.
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Affiliation(s)
- Adrienne Chen
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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133
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Glover DJ, Lipps HJ, Jans DA. Towards safe, non-viral therapeutic gene expression in humans. Nat Rev Genet 2005; 6:299-310. [PMID: 15761468 DOI: 10.1038/nrg1577] [Citation(s) in RCA: 462] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The potential dangers of using viruses to deliver and integrate DNA into host cells in gene therapy have been poignantly highlighted in recent clinical trials. Safer, non-viral gene delivery approaches have been largely ignored in the past because of their inefficient delivery and the resulting transient transgene expression. However, recent advances indicate that efficient, long-term gene expression can be achieved by non-viral means. In particular, integration of DNA can be targeted to specific genomic sites without deleterious consequences and it is possible to maintain transgenes as small episomal plasmids or artificial chromosomes. The application of these approaches to human gene therapy is gradually becoming a reality.
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Affiliation(s)
- Dominic J Glover
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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134
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Bennett NJ, May JS, Stevenson PG. Gamma-herpesvirus latency requires T cell evasion during episome maintenance. PLoS Biol 2005; 3:e120. [PMID: 15769185 PMCID: PMC1065266 DOI: 10.1371/journal.pbio.0030120] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Accepted: 02/01/2005] [Indexed: 01/28/2023] Open
Abstract
The gamma-herpesviruses persist as latent episomes in a dynamic lymphocyte pool. Their consequent need to express a viral episome maintenance protein presents a potential immune target. The glycine-alanine repeat of the Epstein-Barr virus episome maintenance protein, EBNA-1, limits EBNA-1 epitope presentation to CD8(+) T lymphocytes (CTLs). However, CTL recognition occurs in vitro, so the significance of such evasion for viral fitness is unclear. We used the murine gamma-herpesvirus-68 (MHV-68) to define the in vivo contribution of cis-acting CTL evasion to host colonisation. Although the ORF73 episome maintenance protein of MHV-68 lacks a glycine-alanine repeat, it was equivalent to EBNA-1 in conferring limited presentation on linked epitopes. This was associated with reduced protein synthesis and reduced protein degradation. We bypassed the cis-acting evasion of ORF73 by using an internal ribosome entry site to express in trans-a CTL target from the same mRNA. This led to a severe, MHC class I-restricted and CTL-dependent reduction in viral latency. Thus, despite MHV-68 encoding at least two trans-acting CTL evasion proteins, cis-acting evasion during episome maintenance was essential for normal host colonisation.
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Affiliation(s)
- Neil J Bennett
- 1Division of Virology, Department of PathologyUniversity of CambridgeUnited Kingdom
| | - Janet S May
- 1Division of Virology, Department of PathologyUniversity of CambridgeUnited Kingdom
| | - Philip G Stevenson
- 1Division of Virology, Department of PathologyUniversity of CambridgeUnited Kingdom
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135
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Kang MS, Lu H, Yasui T, Sharpe A, Warren H, Cahir-McFarland E, Bronson R, Hung SC, Kieff E. Epstein-Barr virus nuclear antigen 1 does not induce lymphoma in transgenic FVB mice. Proc Natl Acad Sci U S A 2005; 102:820-5. [PMID: 15640350 PMCID: PMC545574 DOI: 10.1073/pnas.0408774102] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The lymphoma-inducing potential of Ig heavy-chain enhancer- and promoter-regulated Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) was evaluated in three transgenic FVB mouse lineages. EBNA1 was expressed at a higher level in transgenic B220(+) splenocytes than in EBV-infected lymphoblastoid cell lines. EBNA1 was also expressed in B220(-) transgenic splenocytes and thymocytes. Before killing and assessments at 18-26 months, EBNA1-transgenic mice did not differ from control mice in mortality. At 18-26 months EBNA1-transgenic mice did not differ from littermate control in ultimate body weight, in spleen size or weight, in lymph node, kidney, liver, or spleen histology, in splenocyte fractions positive for cluster of differentiation (CD)3epsilon, CD4, CD8, CD62L, B220, CD5, IgM, IgD, MHC class II, CD11b, or CD25, or in serum IgM, IgG, or total Ig levels. Lymphomas were not found in spleens or other organs of 18- to 26-month-old EBNA1-transgenic (n=86) or control (n=45) FVB mice. EBNA1-transgenic lineages had a higher pulmonary adenoma prevalence than did littermate controls (39% versus 7%). However, the adenoma prevalence was not higher in EBNA1-transgenic mice than has been described for FVB mice, and EBNA1 was not expressed in normal pulmonary epithelia or adenomas.
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Affiliation(s)
- Myung-Soo Kang
- Channing Laboratory, Infectious Disease Division, Department of Medicine and Microbiology and Molecular Genetics, and Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
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136
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Abstract
Malaria and Epstein-Barr virus (EBV), recognised cofactors for endemic Burkitt's lymphoma, are ubiquitous within the lymphoma belt of Africa, and, unless other cofactors are involved, the tumour should be much more common than it is. Malaria and EBV alone cannot account for the occasional shifting foci and space-time case clusters of endemic Burkitt's lymphoma. Arboviruses and plant tumour promoters are other possible local cofactors that could explain such characteristics. The geographical and age distributions of endemic Burkitt's lymphoma parallel those of potentially oncogenic, mosquito-borne arboviruses. Arboviruses seem to be associated with case clusters of endemic Burkitt's lymphoma, and symptoms compatible with arbovirus infection have been seen immediately before the onset of the tumour. RNA and DNA viruses, including EBV, are promoted by extracts of a commonly used plant, Euphorbia tirucalli, the distribution of which coincides with the boundaries of the lymphoma belt. Extracts of E tirucalli are tumour promoters and can induce the characteristic 8;14 translocation of endemic Burkitt's lymphoma in EBV-infected cell-lines. They also activate latent EBV in infected cells, enhance EBV-mediated cell transformation, and modulate EBV-specific immunity.
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137
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Abstract
Two proteins of Epstein-Barr Virus make formerly unrecognized contributions to maintaining the tumors of Burkitt's lymphomas and Hodgkin's disease. The Epstein-Barr nuclear antigen 1 (EBNA1) protein can support the synthesis and maintenance of the viral genome. New data show that inhibiting EBNA1 in Burkitt's lymphoma cells induces cell death by apoptosis. Therefore, EBNA1 inhibits apoptosis and, according to recent findings, does so independently of other viral genes. The latent membrane protein 2a (LMP2a) binds to signaling molecules that are engaged by the B-cell receptor and inhibits the signaling that is mediated by antigen binding. New findings have revealed how LMP2a overcomes the apoptosis that normally results from the absence of functional B-cell receptors, and explain how Hodgkin's disease tumor cells, which are B cells, survive but lack functional antibodies.
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Affiliation(s)
- Wolfgang Hammerschmidt
- Department of Gene Vectors, GSF-National Research Center for Environment and Health, Marchioninistrasse 25, 81377 Munich, Germany
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138
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Abstract
Epstein-Barr virus (EBV) was discovered 40 years ago from examining electron micrographs of cells cultured from Burkitt's lymphoma, a childhood tumour that is common in sub-Saharan Africa, where its unusual geographical distribution - which matches that of holoendemic malaria -indicated a viral aetiology. However, far from showing a restricted distribution, EBV - a gamma-herpesvirus - was found to be widespread in all human populations and to persist in the vast majority of individuals as a lifelong, asymptomatic infection of the B-lymphocyte pool. Despite such ubiquity, the link between EBV and 'endemic' Burkitt's lymphoma proved consistent and became the first of an unexpectedly wide range of associations discovered between this virus and tumours.
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MESH Headings
- Antigens, Viral/genetics
- Antigens, Viral/physiology
- B-Lymphocytes/pathology
- B-Lymphocytes/virology
- Burkitt Lymphoma/epidemiology
- Burkitt Lymphoma/virology
- Carcinoma/therapy
- Carcinoma/virology
- Cell Transformation, Neoplastic
- Cell Transformation, Viral
- Epstein-Barr Virus Infections/pathology
- Epstein-Barr Virus Infections/virology
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/pathogenicity
- Herpesvirus 4, Human/physiology
- Humans
- Immunocompromised Host
- Killer Cells, Natural/pathology
- Lymphoma/therapy
- Lymphoma/virology
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell/virology
- Lymphoma, T-Cell/virology
- Nasopharyngeal Neoplasms/epidemiology
- Nasopharyngeal Neoplasms/virology
- Stomach Neoplasms/virology
- Viral Proteins/genetics
- Viral Proteins/physiology
- Virus Latency
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Affiliation(s)
- Lawrence S Young
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham, B15 2TT, UK.
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139
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Damania B. Oncogenic gamma-herpesviruses: comparison of viral proteins involved in tumorigenesis. Nat Rev Microbiol 2004; 2:656-68. [PMID: 15263900 DOI: 10.1038/nrmicro958] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Blossom Damania
- Lineberger Comprehensive Cancer Center, Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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140
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Lee SP, Brooks JM, Al-Jarrah H, Thomas WA, Haigh TA, Taylor GS, Humme S, Schepers A, Hammerschmidt W, Yates JL, Rickinson AB, Blake NW. CD8 T cell recognition of endogenously expressed epstein-barr virus nuclear antigen 1. ACTA ACUST UNITED AC 2004; 199:1409-20. [PMID: 15148339 PMCID: PMC2211813 DOI: 10.1084/jem.20040121] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Epstein-Barr virus (EBV) nuclear antigen (EBNA)1 contains a glycine-alanine repeat (GAr) domain that appears to protect the antigen from proteasomal breakdown and, as measured in cytotoxicity assays, from major histocompatibility complex (MHC) class I–restricted presentation to CD8+ T cells. This led to the concept of EBNA1 as an immunologically silent protein that although unique in being expressed in all EBV malignancies, could not be exploited as a CD8 target. Here, using CD8+ T cell clones to native EBNA1 epitopes upstream and downstream of the GAr domain and assaying recognition by interferon γ release, we show that the EBNA1 naturally expressed in EBV-transformed lymphoblastoid cell lines (LCLs) is in fact presented to CD8+ T cells via a proteasome/peptide transporter–dependent pathway. Furthermore, LCL recognition by such CD8+ T cells, although slightly lower than seen with paired lines expressing a GAr-deleted EBNA1 protein, leads to strong and specific inhibition of LCL outgrowth in vitro. Endogenously expressed EBNA1 is therefore accessible to the MHC class I pathway despite GAr-mediated stabilization of the mature protein. We infer that EBNA1-specific CD8+ T cells do play a role in control of EBV infection in vivo and might be exploitable in the control of EBV+ malignancies.
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Affiliation(s)
- Steven P Lee
- Institute for Cancer Studies, University of Birmingham, Vincent Drive, Edgbaston, Birmingham B15 2TT, UK.
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141
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Münz C. Epstein-barr virus nuclear antigen 1: from immunologically invisible to a promising T cell target. ACTA ACUST UNITED AC 2004; 199:1301-4. [PMID: 15148332 PMCID: PMC2211815 DOI: 10.1084/jem.20040730] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1)--the one EBV antigen that is expressed in all EBV-associated malignancies--has long been thought to go undetected by the cell-mediated immune system. However, recent studies show that EBNA1 can be presented to both CD4+ and CD8+ T cells, making it a potential new target for immunotherapy of EBV-related cancers.
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Affiliation(s)
- Christian Münz
- Laboratory of Viral Immunobiology, The Rockefeller University, 1230 York Ave., New York, NY 10021, USA.
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142
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Zhang XS, Wang HH, Hu LF, Li A, Zhang RH, Mai HQ, Xia JC, Chen LZ, Zeng YX. V-val subtype of Epstein-Barr virus nuclear antigen 1 preferentially exists in biopsies of nasopharyngeal carcinoma. Cancer Lett 2004; 211:11-8. [PMID: 15194212 DOI: 10.1016/j.canlet.2004.01.035] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Revised: 01/27/2004] [Accepted: 01/28/2004] [Indexed: 10/26/2022]
Abstract
Epstein-Barr virus (EBV) has been suggested to be involved in pathogenesis of nasopharyngeal carcinoma (NPC). However, EBV infection is ubiquitous, whereas NPC occurs with strong geographic and racial distribution. Whether a substrain of EBV contributes to this phenomenon remains uncertain. Epstein-Barr virus nuclear antigen 1 (EBNA-1) is one of the most frequently detected EBV proteins in NPC tissues. Based on the polymorphism of amino acids at position 487, EBNA-1 is classified into five subtypes: P-ala, P-thr, V-val, V-leu and V-pro. To examine the relationship between subtypes of EBNA-1 and NPC, we determined the subtypes of EBNA-1 in biopsies of NPC, peripheral blood lymphocytes (PBL), and throat washings (TWs) obtained in endemic and non-endemic areas of NPC within China. The results revealed that V-val was the only subtype detected in NPC tissue, whereas three subtypes of EBNA-1, V-val, P-ala, and P-thr, were detected in PBL and TWs irrespective of origin, and mixed infection of V-val and P-ala was also observed. In addition, the variations of V-val derived from biopsies of NPC were identical to those derived from PBL and TWs in the context of N-terminus and C-terminus of EBNA-1. These facts indicate that a substrain of EBV with V-val subtype of EBNA-1 infects NPC preferentially and a susceptibility to a particular EBV isolate in the nasopharynx may exist during development of NPC.
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Affiliation(s)
- Xiao-Shi Zhang
- Department of Experimental Research, Cancer Center, Sun Yat-sen University, 651 Dongfeng Road East, Guangzhou 510060, People's Republic of China
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143
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Affiliation(s)
- Jenny O'Nions
- Faculty of Medicine, Department of Virology and Ludwig Institute for Cancer Research, Imperial College London, Norfolk Place, London W2 1PG, UK
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