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Lurain KA, Ramaswami R, Krug LT, Whitby D, Ziegelbauer JM, Wang HW, Yarchoan R. HIV-associated cancers and lymphoproliferative disorders caused by Kaposi sarcoma herpesvirus and Epstein-Barr virus. Clin Microbiol Rev 2024:e0002223. [PMID: 38899877 DOI: 10.1128/cmr.00022-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024] Open
Abstract
SUMMARYWithin weeks of the first report of acquired immunodeficiency syndrome (AIDS) in 1981, it was observed that these patients often had Kaposi sarcoma (KS), a hitherto rarely seen skin tumor in the USA. It soon became apparent that AIDS was also associated with an increased incidence of high-grade lymphomas caused by Epstein-Barr virus (EBV). The association of AIDS with KS remained a mystery for more than a decade until Kaposi sarcoma-associated herpesvirus (KSHV) was discovered and found to be the cause of KS. KSHV was subsequently found to cause several other diseases associated with AIDS and human immunodeficiency virus (HIV) infection. People living with HIV/AIDS continue to have an increased incidence of certain cancers, and many of these cancers are caused by EBV and/or KSHV. In this review, we discuss the epidemiology, virology, pathogenesis, clinical manifestations, and treatment of cancers caused by EBV and KSHV in persons living with HIV.
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Affiliation(s)
- Kathryn A Lurain
- The HIV and AIDS Malignancy Branch, Center for Cancer Research, Bethesda, Maryland, USA
| | - Ramya Ramaswami
- The HIV and AIDS Malignancy Branch, Center for Cancer Research, Bethesda, Maryland, USA
| | - Laurie T Krug
- The HIV and AIDS Malignancy Branch, Center for Cancer Research, Bethesda, Maryland, USA
| | - Denise Whitby
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Joseph M Ziegelbauer
- The HIV and AIDS Malignancy Branch, Center for Cancer Research, Bethesda, Maryland, USA
| | - Hao-Wei Wang
- Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland, USA
| | - Robert Yarchoan
- The HIV and AIDS Malignancy Branch, Center for Cancer Research, Bethesda, Maryland, USA
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Cable JM, Reinoso-Vizcaino NM, White RE, Luftig MA. Epstein-Barr virus protein EBNA-LP engages YY1 through leucine-rich motifs to promote naïve B cell transformation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.07.574580. [PMID: 38260266 PMCID: PMC10802455 DOI: 10.1101/2024.01.07.574580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Epstein-Barr Virus (EBV) is associated with numerous cancers including B cell lymphomas. In vitro, EBV transforms primary B cells into immortalized Lymphoblastoid Cell Lines (LCLs) which serves as a model to study the role of viral proteins in EBV malignancies. EBV induced cellular transformation is driven by viral proteins including EBV-Nuclear Antigens (EBNAs). EBNA-LP is important for the transformation of naïve but not memory B cells. While EBNA-LP was thought to promote gene activation by EBNA2, EBNA-LP Knock Out (LPKO) virus-infected cells express EBNA2-activated genes efficiently. Therefore, a gap in knowledge exists as to what roles EBNA-LP plays in naïve B cell transformation. We developed a trans-complementation assay wherein transfection with wild-type EBNA-LP rescues the transformation of peripheral blood- and cord blood-derived naïve B cells by LPKO virus. Despite EBNA-LP phosphorylation sites being important in EBNA2 co-activation; neither phospho-mutant nor phospho-mimetic EBNA-LP was defective in rescuing naïve B cell outgrowth. However, we identified conserved leucine-rich motifs in EBNA-LP that were required for transformation of adult naïve and cord blood B cells. Because cellular PPAR-γ coactivator (PGC) proteins use leucine-rich motifs to engage transcription factors including YY1, a key regulator of DNA looping and metabolism, we examined the role of EBNA-LP in engaging cellular transcription factors. We found a significant overlap between EBNA-LP and YY1 in ChIP-Seq data and confirmed their biochemical association in LCLs by endogenous co-immunoprecipitation. Moreover, we found that the EBNA-LP leucine-rich motifs were required for YY1 interaction in LCLs. Finally, we used Cas9 to knockout YY1 in primary total B cells and naïve B cells prior to EBV infection and found YY1 to be essential for EBV-mediated transformation. We propose that EBNA-LP engages YY1 through conserved leucine-rich motifs to promote EBV transformation of naïve B cells.
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Affiliation(s)
- Jana M Cable
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, United States
| | - Nicolás M Reinoso-Vizcaino
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, United States
| | - Robert E. White
- Section of Virology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Micah A Luftig
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, United States
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Zhao B. Epstein-Barr Virus B Cell Growth Transformation: The Nuclear Events. Viruses 2023; 15:832. [PMID: 37112815 PMCID: PMC10146190 DOI: 10.3390/v15040832] [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: 02/08/2023] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 03/29/2023] Open
Abstract
Epstein-Barr virus (EBV) is the first human DNA tumor virus identified from African Burkitt's lymphoma cells. EBV causes ~200,000 various cancers world-wide each year. EBV-associated cancers express latent EBV proteins, EBV nuclear antigens (EBNAs), and latent membrane proteins (LMPs). EBNA1 tethers EBV episomes to the chromosome during mitosis to ensure episomes are divided evenly between daughter cells. EBNA2 is the major EBV latency transcription activator. It activates the expression of other EBNAs and LMPs. It also activates MYC through enhancers 400-500 kb upstream to provide proliferation signals. EBNALP co-activates with EBNA2. EBNA3A/C represses CDKN2A to prevent senescence. LMP1 activates NF-κB to prevent apoptosis. The coordinated activity of EBV proteins in the nucleus allows efficient transformation of primary resting B lymphocytes into immortalized lymphoblastoid cell lines in vitro.
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Affiliation(s)
- Bo Zhao
- Department of Medicine, Division of Infectious Diseases, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
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4
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Wen KW, Wang L, Menke JR, Damania B. Cancers associated with human gammaherpesviruses. FEBS J 2022; 289:7631-7669. [PMID: 34536980 PMCID: PMC9019786 DOI: 10.1111/febs.16206] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 08/10/2021] [Accepted: 09/16/2021] [Indexed: 01/14/2023]
Abstract
Epstein-Barr virus (EBV; human herpesvirus 4; HHV-4) and Kaposi sarcoma-associated herpesvirus (KSHV; human herpesvirus 8; HHV-8) are human gammaherpesviruses that have oncogenic properties. EBV is a lymphocryptovirus, whereas HHV-8/KSHV is a rhadinovirus. As lymphotropic viruses, EBV and KSHV are associated with several lymphoproliferative diseases or plasmacytic/plasmablastic neoplasms. Interestingly, these viruses can also infect epithelial cells causing carcinomas and, in the case of KSHV, endothelial cells, causing sarcoma. EBV is associated with Burkitt lymphoma, classic Hodgkin lymphoma, nasopharyngeal carcinoma, plasmablastic lymphoma, lymphomatoid granulomatosis, leiomyosarcoma, and subsets of diffuse large B-cell lymphoma, post-transplant lymphoproliferative disorder, and gastric carcinoma. KSHV is implicated in Kaposi sarcoma, primary effusion lymphoma, multicentric Castleman disease, and KSHV-positive diffuse large B-cell lymphoma. Pathogenesis by these two herpesviruses is intrinsically linked to viral proteins expressed during the lytic and latent lifecycles. This comprehensive review intends to provide an overview of the EBV and KSHV viral cycles, viral proteins that contribute to oncogenesis, and the current understanding of the pathogenesis and clinicopathology of their related neoplastic entities.
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Affiliation(s)
- Kwun Wah Wen
- Department of Pathology and Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Linlin Wang
- Department of Laboratory Medicine, University of California, San Francisco, CA 94158
| | - Joshua R. Menke
- Department of Pathology, Stanford University, Palo Alto, CA 94304
| | - Blossom Damania
- Department of Microbiology & Immunology & Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
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5
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Rahman R, Gopinath D, Buajeeb W, Poomsawat S, Johnson NW. Potential Role of Epstein–Barr Virus in Oral Potentially Malignant Disorders and Oral Squamous Cell Carcinoma: A Scoping Review. Viruses 2022; 14:v14040801. [PMID: 35458531 PMCID: PMC9032208 DOI: 10.3390/v14040801] [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: 02/15/2022] [Revised: 03/31/2022] [Accepted: 04/01/2022] [Indexed: 12/25/2022] Open
Abstract
Though the oral cavity is anatomically proximate to the nasal cavity and acts as a key reservoir of EBV habitation and transmission, it is still unclear whether EBV plays a significant role in oral carcinogenesis. Many studies have detected EBV DNA in tissues and exfoliated cells from OSCC patients. However, very few studies have investigated the expression of functional EBV proteins implicated in its oncogenicity. The most studied are latent membrane protein 1 (LMP-1), a protein associated with the activation of signalling pathways; EBV determined nuclear antigen (EBNA)-1, a protein involved in the regulation of gene expression; and EBV-encoded small non-polyadenylated RNA (EBER)-2. LMP-1 is considered the major oncoprotein, and overexpression of LMP-1 observed in OSCC indicates that this molecule might play a significant role in oral carcinogenesis. Although numerous studies have detected EBV DNA and proteins from OSCC and oral potentially malignant disorders, heterogeneity in methodologies has led to discrepant results, hindering interpretation. Elucidating the exact functions of EBV and its proteins when expressed is vital in establishing the role of viruses in oral oncogenesis. This review summarises the current evidence on the potential role of EBV in oral oncogenesis and discusses the implications as well as recommendations for future research.
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Affiliation(s)
- Rifat Rahman
- Menzies Health Institute Queensland, School of Medicine and Dentistry, Griffith University, Gold Coast, QLD 4222, Australia; (R.R.); (N.W.J.)
| | - Divya Gopinath
- Clinical Oral Health Sciences Division, School of Dentistry, International Medical University, Kuala Lumpur 57000, Malaysia
- Correspondence:
| | - Waranun Buajeeb
- Department of Oral Medicine and Periodontology, Faculty of Dentistry, Mahidol University, Bangkok 10400, Thailand;
| | - Sopee Poomsawat
- Department of Oral and Maxillofacial Pathology, Faculty of Dentistry, Mahidol University, Bangkok 10400, Thailand;
| | - Newell W. Johnson
- Menzies Health Institute Queensland, School of Medicine and Dentistry, Griffith University, Gold Coast, QLD 4222, Australia; (R.R.); (N.W.J.)
- Faculty of Dentistry, Oral and Craniofacial Sciences, King’s College London, London WC2R 2LS, UK
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6
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Ranger-Rogez S. EBV Genome Mutations and Malignant Proliferations. Infect Dis (Lond) 2021. [DOI: 10.5772/intechopen.93194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The Epstein-Barr virus (EBV) is a DNA virus with a relatively stable genome. Indeed, genomic variability is reported to be around 0.002%. However, some regions are more variable such as those carrying latency genes and specially EBNA1, -2, -LP, and LMP1. Tegument genes, particularly BNRF1, BPLF1, and BKRF3, are also quite mutated. For a long time, it has been considered for this ubiquitous virus, which infects a very large part of the population, that particular strains could be the cause of certain diseases. However, the mutations found, in some cases, are more geographically restricted rather than associated with proliferation. In other cases, they appear to be involved in oncogenesis. The objective of this chapter is to provide an update on changes in viral genome sequences in malignancies associated with EBV. We focused on describing the structure and function of the proteins corresponding to the genes mentioned above in order to understand how certain mutations of these proteins could increase the tumorigenic character of this virus. Mutations described in the literature for these proteins were identified by reporting viral and/or cellular functional changes as they were described.
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Romero-Masters JC, Huebner SM, Ohashi M, Bristol JA, Benner BE, Barlow EA, Turk GL, Nelson SE, Baiu DC, Van Sciver N, Ranheim EA, Gumperz J, Sherer NM, Farrell PJ, Johannsen EC, Kenney SC. B cells infected with Type 2 Epstein-Barr virus (EBV) have increased NFATc1/NFATc2 activity and enhanced lytic gene expression in comparison to Type 1 EBV infection. PLoS Pathog 2020; 16:e1008365. [PMID: 32059024 PMCID: PMC7046292 DOI: 10.1371/journal.ppat.1008365] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 02/27/2020] [Accepted: 01/29/2020] [Indexed: 12/30/2022] Open
Abstract
Humans are infected with two distinct strains (Type 1 (T1) and Type 2 (T2)) of Epstein-Barr virus (EBV) that differ substantially in their EBNA2 and EBNA 3A/B/C latency genes and the ability to transform B cells in vitro. While most T1 EBV strains contain the "prototype" form of the BZLF1 immediate-early promoter ("Zp-P"), all T2 strains contain the "Zp-V3" variant, which contains an NFAT binding motif and is activated much more strongly by B-cell receptor signalling. Whether B cells infected with T2 EBV are more lytic than cells infected with T1 EBV is unknown. Here we show that B cells infected with T2 EBV strains (AG876 and BL5) have much more lytic protein expression compared to B cells infected with T1 EBV strains (M81, Akata, and Mutu) in both a cord blood-humanized (CBH) mouse model and EBV-transformed lymphoblastoid cell lines (LCLs). Although T2 LCLs grow more slowly than T1 LCLs, both EBV types induce B-cell lymphomas in CBH mice. T1 EBV strains (M81 and Akata) containing Zp-V3 are less lytic than T2 EBV strains, suggesting that Zp-V3 is not sufficient to confer a lytic phenotype. Instead, we find that T2 LCLs express much higher levels of activated NFATc1 and NFATc2, and that cyclosporine (an NFAT inhibitor) and knockdown of NFATc2 attenuate constitutive lytic infection in T2 LCLs. Both NFATc1 and NFATc2 induce lytic EBV gene expression when combined with activated CAMKIV (which is activated by calcium signaling and activates MEF2D) in Burkitt Akata cells. Together, these results suggest that B cells infected with T2 EBV are more lytic due to increased activity of the cellular NFATc1/c2 transcription factors in addition to the universal presence of the Zp-V3 form of BZLF1 promoter.
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Affiliation(s)
- James C. Romero-Masters
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Shane M. Huebner
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Makoto Ohashi
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Jillian A. Bristol
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Bayleigh E. Benner
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Elizabeth A. Barlow
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Gail L. Turk
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Scott E. Nelson
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Dana C. Baiu
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Nicholas Van Sciver
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Erik A. Ranheim
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Jenny Gumperz
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Nathan M. Sherer
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Paul J. Farrell
- Section of Virology, Imperial College Faculty of Medicine, Norfolk Place, London, United Kingdom
| | - Eric C. Johannsen
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Shannon C. Kenney
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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8
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Ayee R, Ofori MEO, Wright E, Quaye O. Epstein Barr Virus Associated Lymphomas and Epithelia Cancers in Humans. J Cancer 2020; 11:1737-1750. [PMID: 32194785 PMCID: PMC7052849 DOI: 10.7150/jca.37282] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 12/01/2019] [Indexed: 02/06/2023] Open
Abstract
Epstein Barr virus (EBV) is a cosmopolitan oncogenic virus, infecting about 90% of the world's population and it is associated to tumors originating from both epithelia and hematopoietic cells. Transmission of the virus is mainly through oral secretions; however, transmission through organ transplantation and blood transfusion has been reported. In order to evade immune recognition, EBV establishes latent infection in B lymphocytes where it expresses limited sets of proteins called EBV transcription programs (ETPs), including six nuclear antigens (EBNAs), three latent membrane proteins (LMP), and untranslated RNA called EBV encoded RNA (EBER), shown to efficiently transform B cells into lymphoblastic cells. These programs undergo different patterns of expression which determine the occurrence of distinct types of latency in the pathogenesis of a particular tumor. Hematopoietic cell derived tumors include but not limited to Burkitt's lymphoma, Hodgkin lymphoma, post-transplant lymphoproliferative disorders, and natural killer (NK)/T cell lymphoma. EBV undergoes lytic infection in epithelia cells for amplification of the viral particle for transmission where it expresses lytic stage genes. However, for reasons yet to be unveiled, EBV switches from the expression of lytic stage genes to the expression of ETPs in epithelia cells. The expression of the ETPs lead to the transformation of epithelia cells into permanently proliferating cells, resulting in epithelia cell derived malignancies such as nasopharyngeal cancer, gastric cancer, and breast cancer. In this review, we have summarized the current updates on EBV associated epithelial and B cell-derived malignancies, and the role of EBV latency gene products in the pathogenesis of the cancers, and have suggested areas for future studies when considering therapeutic measures.
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Affiliation(s)
- Richmond Ayee
- Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
- West African Center for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Legon, Accra, Ghana
| | | | - Edward Wright
- Department of Biochemistry, University of Sussex, Brighton, U.K
| | - Osbourne Quaye
- Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
- West African Center for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Legon, Accra, Ghana
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Mechanisms of B-Cell Oncogenesis Induced by Epstein-Barr Virus. J Virol 2019; 93:JVI.00238-19. [PMID: 30971472 PMCID: PMC6580952 DOI: 10.1128/jvi.00238-19] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 04/08/2019] [Indexed: 12/12/2022] Open
Abstract
Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus which asymptomatically infects the majority of the world population. Under immunocompromised conditions, EBV can trigger human cancers of epithelial and lymphoid origin. The oncogenic potential of EBV is demonstrated by in vitro infection and transformation of quiescent B cells into lymphoblastoid cell lines (LCLs). These cell lines, along with primary infection using genetically engineered viral particles coupled with recent technological advancements, have elucidated the underlying mechanisms of EBV-induced B-cell lymphomagenesis.
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Wang C, Zhou H, Xue Y, Liang J, Narita Y, Gerdt C, Zheng AY, Jiang R, Trudeau S, Peng CW, Gewurz BE, Zhao B. Epstein-Barr Virus Nuclear Antigen Leader Protein Coactivates EP300. J Virol 2018; 92:e02155-17. [PMID: 29467311 PMCID: PMC5899200 DOI: 10.1128/jvi.02155-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 02/10/2018] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus nuclear antigen (EBNA) leader protein (EBNALP) is one of the first viral genes expressed upon B-cell infection. EBNALP is essential for EBV-mediated B-cell immortalization. EBNALP is thought to function primarily by coactivating EBNA2-mediated transcription. Chromatin immune precipitation followed by deep sequencing (ChIP-seq) studies highlight that EBNALP frequently cooccupies DNA sites with host cell transcription factors (TFs), in particular, EP300, implicating a broader role in transcription regulation. In this study, we investigated the mechanisms of EBNALP transcription coactivation through EP300. EBNALP greatly enhanced EP300 transcription activation when EP300 was tethered to a promoter. EBNALP coimmunoprecipitated endogenous EP300 from lymphoblastoid cell lines (LCLs). EBNALP W repeat serine residues 34, 36, and 63 were required for EP300 association and coactivation. Deletion of the EP300 histone acetyltransferase (HAT) domain greatly reduced EBNALP coactivation and abolished the EBNALP association. An EP300 bromodomain inhibitor also abolished EBNALP coactivation and blocked the EP300 association with EBNALP. EBNALP sites cooccupied by EP300 had significantly higher ChIP-seq signals for sequence-specific TFs, including SPI1, RelA, EBF1, IRF4, BATF, and PAX5. EBNALP- and EP300-cooccurring sites also had much higher H3K4me1 and H3K27ac signals, indicative of activated enhancers. EBNALP-only sites had much higher signals for DNA looping factors, including CTCF and RAD21. EBNALP coactivated reporters under the control of NF-κB or SPI1. EP300 inhibition abolished EBNALP coactivation of these reporters. Clustered regularly interspaced short palindromic repeat interference targeting of EBNALP enhancer sites significantly reduced target gene expression, including that of EP300 itself. These data suggest a previously unrecognized mechanism by which EBNALP coactivates transcription through subverting of EP300 and thus affects the expression of LCL genes regulated by a broad range of host TFs.IMPORTANCE Epstein-Barr virus was the first human DNA tumor virus discovered over 50 years ago. EBV is causally linked to ∼200,000 human malignancies annually. These cancers include endemic Burkitt lymphoma, Hodgkin lymphoma, lymphoma/lymphoproliferative disease in transplant recipients or HIV-infected people, nasopharyngeal carcinoma, and ∼10% of gastric carcinoma cases. EBV-immortalized human B cells faithfully model key aspects of EBV lymphoproliferative diseases and are useful models of EBV oncogenesis. EBNALP is essential for EBV to transform B cells and transcriptionally coactivates EBNA2 by removing repressors from EBNA2-bound DNA sites. Here, we found that EBNALP can also modulate the activity of the key transcription activator EP300, an acetyltransferase that activates a broad range of transcription factors. Our data suggest that EBNALP regulates a much broader range of host genes than was previously appreciated. A small-molecule inhibitor of EP300 abolished EBNALP coactivation of multiple target genes. These findings suggest novel therapeutic approaches to control EBV-associated lymphoproliferative diseases.
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Affiliation(s)
- Chong Wang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Hufeng Zhou
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Yong Xue
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jun Liang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Yohei Narita
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Catherine Gerdt
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Amy Y Zheng
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Runsheng Jiang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Stephen Trudeau
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Chih-Wen Peng
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Benjamin E Gewurz
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Bo Zhao
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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11
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Szymula A, Palermo RD, Bayoumy A, Groves IJ, Ba abdullah M, Holder B, White RE. Epstein-Barr virus nuclear antigen EBNA-LP is essential for transforming naïve B cells, and facilitates recruitment of transcription factors to the viral genome. PLoS Pathog 2018; 14:e1006890. [PMID: 29462212 PMCID: PMC5834210 DOI: 10.1371/journal.ppat.1006890] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 03/02/2018] [Accepted: 01/21/2018] [Indexed: 12/11/2022] Open
Abstract
The Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) is the first viral latency-associated protein produced after EBV infection of resting B cells. Its role in B cell transformation is poorly defined, but it has been reported to enhance gene activation by the EBV protein EBNA2 in vitro. We generated EBNA-LP knockout (LPKO) EBVs containing a STOP codon within each repeat unit of internal repeat 1 (IR1). EBNA-LP-mutant EBVs established lymphoblastoid cell lines (LCLs) from adult B cells at reduced efficiency, but not from umbilical cord B cells, which died approximately two weeks after infection. Adult B cells only established EBNA-LP-null LCLs with a memory (CD27+) phenotype. Quantitative PCR analysis of virus gene expression after infection identified both an altered ratio of the EBNA genes, and a dramatic reduction in transcript levels of both EBNA2-regulated virus genes (LMP1 and LMP2) and the EBNA2-independent EBER genes in the first 2 weeks. By 30 days post infection, LPKO transcription was the same as wild-type EBV. In contrast, EBNA2-regulated cellular genes were induced efficiently by LPKO viruses. Chromatin immunoprecipitation revealed that EBNA2 and the host transcription factors EBF1 and RBPJ were delayed in their recruitment to all viral latency promoters tested, whereas these same factors were recruited efficiently to several host genes, which exhibited increased EBNA2 recruitment. We conclude that EBNA-LP does not simply co-operate with EBNA2 in activating gene transcription, but rather facilitates the recruitment of several transcription factors to the viral genome, to enable transcription of virus latency genes. Additionally, our findings suggest that EBNA-LP is essential for the survival of EBV-infected naïve B cells. Epstein-Barr virus (EBV) infects almost everyone. Once infected, people harbor the virus for life, shedding it in saliva. Infection of children is asymptomatic, but a first infection during adolescence or adulthood can cause glandular fever (infectious mononucleosis). EBV is also implicated in several different cancers. EBV infection of B cells (antibody-producing immune cells) can drive them to replicate almost indefinitely (‘transformation’), generating cell lines. We have investigated the role of an EBV protein (EBNA-LP) which is thought to support gene activation by the essential virus protein EBNA2. We have made an EBV in which the EBNA-LP gene has been disrupted. This virus (LPKO) shows several properties. 1. It is reduced in its ability to transform B cells; 2. ‘Naïve’ B cells (those whose antibodies have not adapted to fight infections) die two weeks after LPKO infection; 3. Some virus genes fail to turn on immediately after LPKO infection. 4. Binding of EBNA2 and various cellular factors to these genes is delayed. 5. EBNA-LP does not affect EBNA2-targeted cellular genes in the same way. This shows that EBNA-LP is more important in naïve B cells, and that it helps to turn on virus genes, but not cell genes.
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MESH Headings
- Adult
- B-Lymphocytes/pathology
- B-Lymphocytes/virology
- Cell Transformation, Viral/genetics
- Cells, Cultured
- Epstein-Barr Virus Infections/complications
- Epstein-Barr Virus Infections/genetics
- Epstein-Barr Virus Infections/pathology
- Female
- Gene Expression Regulation, Viral
- Genome, Viral
- HEK293 Cells
- Herpesvirus 4, Human/genetics
- Humans
- Infant, Newborn
- Leukemia, B-Cell/genetics
- Leukemia, B-Cell/pathology
- Leukemia, B-Cell/virology
- Pregnancy
- Promoter Regions, Genetic
- Protein Binding/genetics
- Transcription Factors/metabolism
- Viral Proteins/physiology
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Affiliation(s)
- Agnieszka Szymula
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Richard D. Palermo
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Amr Bayoumy
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Ian J. Groves
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Mohammed Ba abdullah
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Beth Holder
- Section of Pediatrics, Department of Medicine, Imperial College London, London, United Kingdom
| | - Robert E. White
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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12
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New Interactors of the Truncated EBNA-LP Protein Identified by Mass Spectrometry in P3HR1 Burkitt's Lymphoma Cells. Cancers (Basel) 2018; 10:cancers10010012. [PMID: 29303964 PMCID: PMC5789362 DOI: 10.3390/cancers10010012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 01/07/2023] Open
Abstract
The Epstein-Barr virus nuclear antigen leader protein (EBNA-LP) acts as a co-activator of EBNA-2, a transcriptional activator essential for Epstein-Barr virus (EBV)-induced B-cell transformation. Burkitt's lymphoma (BL) cells harboring a mutant EBV strain that lacks both the EBNA-2 gene and 3' exons of EBNA-LP express Y1Y2-truncated isoforms of EBNA-LP (tEBNA-LP) and better resist apoptosis than if infected with the wild-type virus. In such BL cells, tEBNA-LP interacts with the protein phosphatase 2A (PP2A) catalytic subunit (PP2A C), and this interaction likely plays a role in resistance to apoptosis. Here, 28 cellular and four viral proteins have been identified by mass spectrometry as further possible interactors of tEBNA-LP. Three interactions were confirmed by immunoprecipitation and Western blotting, namely with the A structural subunit of PP2A (PP2A A), the structure-specific recognition protein 1 (SSRP1, a component of the facilitate chromatin transcription (FACT) complex), and a new form of the transcription factor EC (TFEC). Thus, tEBNA-LP appears to be involved not only in cell resistance to apoptosis through its interaction with two PP2A subunits, but also in other processes where its ability to co-activate transcriptional regulators could be important.
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13
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Yoshida M, Murata T, Ashio K, Narita Y, Watanabe T, Masud HMAA, Sato Y, Goshima F, Kimura H. Characterization of a Suppressive Cis-acting Element in the Epstein-Barr Virus LMP1 Promoter. Front Microbiol 2017; 8:2302. [PMID: 29213259 PMCID: PMC5702780 DOI: 10.3389/fmicb.2017.02302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/08/2017] [Indexed: 01/08/2023] Open
Abstract
Latent membrane protein 1 (LMP1) is a major oncogene encoded by Epstein–Barr virus (EBV) and is essential for immortalization of B cells by the virus. Previous studies suggested that several transcription factors, such as PU.1, RBP-Jκ, NFκB, EBF1, AP-2 and STAT, are involved in LMP1 induction; however, the means by which the oncogene is negatively regulated remains unclear. Here, we introduced short mutations into the proximal LMP1 promoter that includes recognition sites for the E-box and Ikaros transcription factors in the context of EBV-bacterial artificial chromosome. Upon infection, the mutant exhibited increased LMP1 expression and EBV-mediated immortalization of B cells. However, single mutations of either the E-box or Ikaros sites had limited effects on LMP1 expression and transformation. Our results suggest that this region contains a suppressive cis-regulatory element, but other transcriptional repressors (apart from the E-box and Ikaros transcription factors) may remain to be discovered.
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Affiliation(s)
- Masahiro Yoshida
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takayuki Murata
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Department of Virology and Parasitology, Fujita Health University School of Medicine, Toyoake, Japan
| | - Keiji Ashio
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yohei Narita
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takahiro Watanabe
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - H M Abdullah Al Masud
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshitaka Sato
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Fumi Goshima
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Kimura
- Department of Virology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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14
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Poling BC, Price AM, Luftig MA, Cullen BR. The Epstein-Barr virus miR-BHRF1 microRNAs regulate viral gene expression in cis. Virology 2017; 512:113-123. [PMID: 28950226 DOI: 10.1016/j.virol.2017.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/05/2017] [Accepted: 09/18/2017] [Indexed: 10/18/2022]
Abstract
The Epstein-Barr virus (EBV) miR-BHRF1 microRNA (miRNA) cluster has been shown to facilitate B-cell transformation and promote the rapid growth of the resultant lymphoblastoid cell lines (LCLs). However, we find that expression of physiological levels of the miR-BHRF1 miRNAs in LCLs transformed with a miR-BHRF1 null mutant (∆123) fails to increase their growth rate. We demonstrate that the pri-miR-BHRF1-2 and 1-3 stem-loops are present in the 3'UTR of transcripts encoding EBNA-LP and that excision of pre-miR-BHRF1-2 and 1-3 by Drosha destabilizes these mRNAs and reduces expression of the encoded protein. Therefore, mutational inactivation of pri-miR-BHRF1-2 and 1-3 in the ∆123 mutant upregulates the expression of not only EBNA-LP but also EBNA-LP-regulated mRNAs and proteins, including LMP1. We hypothesize that this overexpression causes the reduced transformation capacity of the ∆123 EBV mutant. Thus, in addition to regulating cellular mRNAs in trans, miR-BHRF1-2 and 1-3 also regulate EBNA-LP mRNA expression in cis.
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Affiliation(s)
- Brigid Chiyoko Poling
- Department of Molecular Genetics & Microbiology and Center for Virology, Duke University Medical Center, Durham, NC, USA.
| | - Alexander M Price
- Department of Molecular Genetics & Microbiology and Center for Virology, Duke University Medical Center, Durham, NC, USA.
| | - Micah A Luftig
- Department of Molecular Genetics & Microbiology and Center for Virology, Duke University Medical Center, Durham, NC, USA.
| | - Bryan R Cullen
- Department of Molecular Genetics & Microbiology and Center for Virology, Duke University Medical Center, Durham, NC, USA.
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15
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Nakada R, Matsuura Y. Crystal structure of importin-α bound to the nuclear localization signal of Epstein-Barr virus EBNA-LP protein. Protein Sci 2017; 26:1231-1235. [PMID: 28383161 DOI: 10.1002/pro.3173] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 04/01/2017] [Accepted: 04/03/2017] [Indexed: 11/09/2022]
Abstract
Epstein-Barr virus EBNA-LP protein is a transcriptional coactivator of EBNA2. Efficient nuclear localization of EBNA-LP is essential for cooperation with EBNA2. Here, we report the crystal structure of the nuclear import adaptor importin-α1 bound to the nuclear localization signal (NLS) of EBNA-LP that shows EBNA-LP residues 44-RRVRRR-49 binding to the major NLS-binding site at the P0-P5 positions. In contrast to previously characterized classical NLSs that invariably have a basic residue [either lysine (in the vast majority of cases) or arginine] at the P2 position, the EBNA-LP NLS is unique in that it has valine at the P2 position. The loss of the critical P2 lysine (or arginine) is compensated by arginine at the P0 position in the EBNA-LP NLS.
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Affiliation(s)
- Ryohei Nakada
- Division of Biological Science, Graduate School of Science, Nagoya University, Japan
| | - Yoshiyuki Matsuura
- Division of Biological Science, Graduate School of Science, Nagoya University, Japan.,Structural Biology Research Center, Graduate School of Science, Nagoya University, Japan
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16
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Induction of Epstein-Barr Virus Oncoprotein LMP1 by Transcription Factors AP-2 and Early B Cell Factor. J Virol 2016; 90:3873-3889. [PMID: 26819314 DOI: 10.1128/jvi.03227-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 01/21/2016] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Latent membrane protein 1 (LMP1) is a major oncogene essential for primary B cell transformation by Epstein-Barr virus (EBV). Previous studies suggested that some transcription factors, such as PU.1, RBP-Jκ, NF-κB, and STAT, are involved in this expression, but the underlying mechanism is unclear. Here, we identified binding sites for PAX5, AP-2, and EBF in the proximal LMP1 promoter (ED-L1p). We first confirmed the significance of PU.1 and POU domain transcription factor binding for activation of the promoter in latency III. We then focused on the transcription factors AP-2 and early B cell factor (EBF). Interestingly, among the three AP-2-binding sites in the LMP1 promoter, two motifs were also bound by EBF. Overexpression, knockdown, and mutagenesis in the context of the viral genome indicated that AP-2 plays an important role in LMP1 expression in latency II in epithelial cells. In latency III B cells, on the other hand, the B cell-specific transcription factor EBF binds to the ED-L1p and activates LMP1 transcription from the promoter. IMPORTANCE Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) is crucial for B cell transformation and oncogenesis of other EBV-related malignancies, such as nasopharyngeal carcinoma and T/NK lymphoma. Its expression is largely dependent on the cell type or condition, and some transcription factors have been implicated in its regulation. However, these previous reports evaluated the significance of specific factors mostly by reporter assay. In this study, we prepared point-mutated EBV at the binding sites of such transcription factors and confirmed the importance of AP-2, EBF, PU.1, and POU domain factors. Our results will provide insight into the transcriptional regulation of the major oncogene LMP1.
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17
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Harter MR, Liu CD, Shen CL, Gonzalez-Hurtado E, Zhang ZM, Xu M, Martinez E, Peng CW, Song J. BS69/ZMYND11 C-Terminal Domains Bind and Inhibit EBNA2. PLoS Pathog 2016; 12:e1005414. [PMID: 26845565 PMCID: PMC4742278 DOI: 10.1371/journal.ppat.1005414] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 01/04/2016] [Indexed: 12/20/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) plays an important role in driving immortalization of EBV-infected B cells through regulating the expression of many viral and cellular genes. We report a structural study of the tumor suppressor BS69/ZMYND11 C-terminal region, comprised of tandem coiled-coil-MYND domains (BS69CC-MYND), in complex with an EBNA2 peptide containing a PXLXP motif. The coiled-coil domain of BS69 self-associates to bring two separate MYND domains in close proximity, thereby enhancing the BS69 MYND-EBNA2 interaction. ITC analysis of BS69CC-MYND with a C-terminal fragment of EBNA2 further suggests that the BS69CC-MYND homodimer synergistically binds to the two EBNA2 PXLXP motifs that are respectively located in the conserved regions CR7 and CR8. Furthermore, we showed that EBNA2 interacts with BS69 and down-regulates its expression at both mRNA and protein levels in EBV-infected B cells. Ectopic BS69CC-MYND is recruited to viral target promoters through interactions with EBNA2, inhibits EBNA2-mediated transcription activation, and impairs proliferation of lymphoblastoid cell lines (LCLs). Substitution of critical residues in the MYND domain impairs the BS69-EBNA2 interaction and abolishes the BS69 inhibition of the EBNA2-mediated transactivation and LCL proliferation. This study identifies the BS69 C-terminal domains as an inhibitor of EBNA2, which may have important implications in development of novel therapeutic strategies against EBV infection. Since the discovery of Epstein-Barr virus (EBV) 50 years ago, the etiologic links between EBV and a variety of human cancers have gained wide recognition. It is estimated that >90% of the worldwide population carry this virus, which causes over 200,000 cancers across the world every year. One of the key proteins in driving immortalization of EBV-infected B cells is Epstein-Barr virus nuclear antigen 2 (EBNA2), which regulates the expression of many cellular and viral genes. However, the molecular mechanism underlying the interactions between EBNA2 and cellular transcriptional regulators remains enigmatic. Here, we determined the crystal structure of the coiled-coil and MYND tandem domains of BS69/ZMYND11, a candidate tumor suppressor, in complex with an EBNA2 peptide containing a PXLXP motif. We found that the coiled-coil and MYND domains of BS69 cooperate in binding to EBNA2. We also showed that EBNA2 interacts with BS69 and down-regulates its expression at both mRNA and protein levels in EBV-associated B cells. Ectopic BS69 coiled-coil-MYND dual domain is recruited to viral target promoters through interaction with EBNA2, inhibits EBNA2-mediated transcription activation, and impairs proliferation of lymphoblastoid cell lines (LCLs). Together, this study identifies the BS69 C-terminal domains as an inhibitor of EBNA2.
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Affiliation(s)
- Matthew R. Harter
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
| | - Cheng-Der Liu
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Chih-Lung Shen
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Elsie Gonzalez-Hurtado
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
- MARC U-STAR Program, University of California, Riverside, Riverside, California, United States of America
| | - Zhi-Min Zhang
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
| | - Muyu Xu
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
| | - Ernest Martinez
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
- MARC U-STAR Program, University of California, Riverside, Riverside, California, United States of America
| | - Chih-Wen Peng
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
- * E-mail: (CWP); (JS)
| | - Jikui Song
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
- * E-mail: (CWP); (JS)
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18
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Abstract
While all herpesviruses can switch between lytic and latent life cycle, which are both driven by specific transcription programs, a unique feature of latent EBV infection is the expression of several distinct and well-defined viral latent transcription programs called latency I, II, and III. Growth transformation of B-cells by EBV in vitro is based on the concerted action of Epstein-Barr virus nuclear antigens (EBNAs) and latent membrane proteins(LMPs). EBV growth-transformed B-cells express a viral transcriptional program, termed latency III, which is characterized by the coexpression of EBNA2 and EBNA-LP with EBNA1, EBNA3A, -3B, and -3C as well as LMP1, LMP2A, and LMP2B. The focus of this review will be to discuss the current understanding of how two of these proteins, EBNA2 and EBNA-LP, contribute to EBV-mediated B-cell growth transformation.
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Affiliation(s)
- Bettina Kempkes
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Marchioninistr. 25, 81377, Munich, Germany.
| | - Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA.
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19
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McClellan MJ, Wood CD, Ojeniyi O, Cooper TJ, Kanhere A, Arvey A, Webb HM, Palermo RD, Harth-Hertle ML, Kempkes B, Jenner RG, West MJ. Modulation of enhancer looping and differential gene targeting by Epstein-Barr virus transcription factors directs cellular reprogramming. PLoS Pathog 2013; 9:e1003636. [PMID: 24068937 PMCID: PMC3771879 DOI: 10.1371/journal.ppat.1003636] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 08/03/2013] [Indexed: 12/28/2022] Open
Abstract
Epstein-Barr virus (EBV) epigenetically reprogrammes B-lymphocytes to drive immortalization and facilitate viral persistence. Host-cell transcription is perturbed principally through the actions of EBV EBNA 2, 3A, 3B and 3C, with cellular genes deregulated by specific combinations of these EBNAs through unknown mechanisms. Comparing human genome binding by these viral transcription factors, we discovered that 25% of binding sites were shared by EBNA 2 and the EBNA 3s and were located predominantly in enhancers. Moreover, 80% of potential EBNA 3A, 3B or 3C target genes were also targeted by EBNA 2, implicating extensive interplay between EBNA 2 and 3 proteins in cellular reprogramming. Investigating shared enhancer sites neighbouring two new targets (WEE1 and CTBP2) we discovered that EBNA 3 proteins repress transcription by modulating enhancer-promoter loop formation to establish repressive chromatin hubs or prevent assembly of active hubs. Re-ChIP analysis revealed that EBNA 2 and 3 proteins do not bind simultaneously at shared sites but compete for binding thereby modulating enhancer-promoter interactions. At an EBNA 3-only intergenic enhancer site between ADAM28 and ADAMDEC1 EBNA 3C was also able to independently direct epigenetic repression of both genes through enhancer-promoter looping. Significantly, studying shared or unique EBNA 3 binding sites at WEE1, CTBP2, ITGAL (LFA-1 alpha chain), BCL2L11 (Bim) and the ADAMs, we also discovered that different sets of EBNA 3 proteins bind regulatory elements in a gene and cell-type specific manner. Binding profiles correlated with the effects of individual EBNA 3 proteins on the expression of these genes, providing a molecular basis for the targeting of different sets of cellular genes by the EBNA 3s. Our results therefore highlight the influence of the genomic and cellular context in determining the specificity of gene deregulation by EBV and provide a paradigm for host-cell reprogramming through modulation of enhancer-promoter interactions by viral transcription factors. Epstein-Barr virus (EBV) is associated with numerous cancers. The ability of the virus to infect B-cells and convert them from short-lived into immortal cells is the key to its cancer-promoting properties. A small number of EBV transcription factors are required for immortalization and act in concert to drive cell growth by deregulating the expression of cellular genes through largely unknown mechanisms. We have demonstrated that four of these key transcription factors function cooperatively by targeting common genes via long-range enhancer elements and modulating their looping interactions with gene promoters. Specifically we show that gene repression by the EBV EBNA 3 family of proteins can be mediated through the modulation of enhancer-promoter looping. Our results also reveal that different subsets of EBNA 3 proteins are bound at different genes and that this differential binding can vary in lymphoma cells compared to cells immortalized in culture, indicating that cell-background-specific gene regulation may be important in lymphoma development. Our results demonstrate how cellular genes can be deregulated by an oncogenic virus through modulation of enhancer-promoter looping with the specificity of binding by viral transcription factors controlling cellular reprogramming in a gene and cell-type specific manner.
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Affiliation(s)
- Michael J. McClellan
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
| | - C. David Wood
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
| | - Opeoluwa Ojeniyi
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
| | - Tim J. Cooper
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
| | - Aditi Kanhere
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, Paul O'Gorman Building, University College London, London, United Kingdom
| | - Aaron Arvey
- Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Helen M. Webb
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
| | - Richard D. Palermo
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
| | - Marie L. Harth-Hertle
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany
| | - Bettina Kempkes
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany
| | - Richard G. Jenner
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, Paul O'Gorman Building, University College London, London, United Kingdom
| | - Michelle J. West
- School of Life Sciences, John Maynard-Smith Building, University of Sussex, Falmer, Brighton, United Kingdom
- * E-mail:
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20
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Epstein-Barr virus BamHI W repeat number limits EBNA2/EBNA-LP coexpression in newly infected B cells and the efficiency of B-cell transformation: a rationale for the multiple W repeats in wild-type virus strains. J Virol 2011; 85:12362-75. [PMID: 21957300 DOI: 10.1128/jvi.06059-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The genome of Epstein-Barr virus (EBV), a gammaherpesvirus with potent B-cell growth-transforming ability, contains multiple copies of a 3-kb BamHI W repeat sequence; each repeat carries (i) a promoter (Wp) that initiates transformation by driving EBNA-LP and EBNA2 expression and (ii) the W1W2 exons encoding the functionally active repeat domain of EBNA-LP. The W repeat copy number of a virus therefore influences two potential determinants of its transforming ability: the number of available Wp copies and the maximum size of the encoded EBNA-LP. Here, using recombinant EBVs, we show that optimal B-cell transformation requires a minimum of 5 W repeats (5W); the levels of transforming ability fall progressively with viruses carrying 4, 3, and 2 W repeats, as do the levels of Wp-initiated transcripts expressed early postinfection (p.i.), while viruses with 1 copy of the wild-type W repeat (1W) and 0W are completely nontransforming. We therefore suggest that genetic analyses of EBV transforming function should ensure that wild-type and mutant strains have equal numbers (ideally at least 5) of W copies if the analysis is not to be compromised. Attempts to enhance the transforming function of low-W-copy-number viruses, via the activity of helper EBV strains or by gene repair, suggested that the critical defect is not related to EBNA-LP size but to the failure to achieve sufficiently strong coexpression of EBNA-LP and EBNA2 early postinfection. We further show by the results of ex vivo assays that EBV strains in the blood of infected individuals typically have a mean of 5 to 8 W copies, consistent with the view that evolution has selected for viruses with an optimal transforming function.
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21
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C-terminal region of EBNA-2 determines the superior transforming ability of type 1 Epstein-Barr virus by enhanced gene regulation of LMP-1 and CXCR7. PLoS Pathog 2011; 7:e1002164. [PMID: 21857817 PMCID: PMC3145799 DOI: 10.1371/journal.ppat.1002164] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 05/30/2011] [Indexed: 12/22/2022] Open
Abstract
Type 1 Epstein-Barr virus (EBV) strains immortalize B lymphocytes in vitro much more efficiently than type 2 EBV, a difference previously mapped to the EBNA-2 locus. Here we demonstrate that the greater transforming activity of type 1 EBV correlates with a stronger and more rapid induction of the viral oncogene LMP-1 and the cell gene CXCR7 (which are both required for proliferation of EBV-LCLs) during infection of primary B cells with recombinant viruses. Surprisingly, although the major sequence differences between type 1 and type 2 EBNA-2 lie in N-terminal parts of the protein, the superior ability of type 1 EBNA-2 to induce proliferation of EBV-infected lymphoblasts is mostly determined by the C-terminus of EBNA-2. Substitution of the C-terminus of type 1 EBNA-2 into the type 2 protein is sufficient to confer a type 1 growth phenotype and type 1 expression levels of LMP-1 and CXCR7 in an EREB2.5 cell growth assay. Within this region, the RG, CR7 and TAD domains are the minimum type 1 sequences required. Sequencing the C-terminus of EBNA-2 from additional EBV isolates showed high sequence identity within type 1 isolates or within type 2 isolates, indicating that the functional differences mapped are typical of EBV type sequences. The results indicate that the C-terminus of EBNA-2 accounts for the greater ability of type 1 EBV to promote B cell proliferation, through mechanisms that include higher induction of genes (LMP-1 and CXCR7) required for proliferation and survival of EBV-LCLs. Epstein-Barr virus (EBV) is a common human virus that is involved in several types of cancer and directly causes human B lymphocytes to proliferate when they become infected. EBV occurs naturally as two different viral types (type 1 and type 2). The genomes of these viruses are mostly very similar but they differ in a few genes, particularly the EBNA-2 gene. For many years it has been known that type 1 EBV is much more effective than type 2 EBV at causing B lymphocyte proliferation and this difference is mediated by the EBNA-2 gene. Here we have shown that the greater ability of type 1 EBNA-2 to cause B cell proliferation is due to superior induction of the EBV LMP-1 and the cell CXCR7 genes, both of which are required for growth of EBV-infected lymphocytes. We mapped the section of type 1 EBNA-2 responsible for this to the C-terminus of the protein, including the transactivation and EBNA-LP interaction domains. The results provide a mechanism for the long-standing question of the functional difference between these two major types of EBV and will be important in understanding the significance of the EBV types in human infection.
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Niller HH, Wolf H, Ay E, Minarovits J. Epigenetic dysregulation of epstein-barr virus latency and development of autoimmune disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 711:82-102. [PMID: 21627044 DOI: 10.1007/978-1-4419-8216-2_7] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Epstein-Barr virus (EBV) is ahumanherpesvirus thatpersists in the memory B-cells of the majority of the world population in a latent form. Primary EBV infection is asymptomatic or causes a self-limiting disease, infectious mononucleosis. Virus latency is associated with a wide variety of neoplasms whereof some occur in immune suppressed individuals. Virus production does not occur in strict latency. The expression of latent viral oncoproteins and nontranslated RNAs is under epigenetic control via DNA methylation and histone modifications that results either in a complete silencing of the EBV genome in memory B cells, or in a cell-type dependent usage of a couple of latency promoters in tumor cells, germinal center B cells and lymphoblastoid cells (LCL, transformed by EBV in vitro). Both, latent and lytic EBV proteins elicit a strong immune response. In immune suppressed and infectious mononucleosis patients, an increased viral load can be detected in the blood. Enhanced lytic replication may result in new infection- and transformation-events and thus is a risk factor both for malignant transformation and the development of autoimmune diseases. An increased viral load or a changed presentation of a subset of lytic or latent EBV proteins that cross-react with cellular antigens may trigger pathogenic processes through molecular mimicry that result in multiple sclerosis (MS), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).
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Affiliation(s)
- Hans Helmut Niller
- Institute for Medical Microbiology and Hygiene of the University of Regensburg, Regensburg, Germany.
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White RE, Groves IJ, Turro E, Yee J, Kremmer E, Allday MJ. Extensive co-operation between the Epstein-Barr virus EBNA3 proteins in the manipulation of host gene expression and epigenetic chromatin modification. PLoS One 2010; 5:e13979. [PMID: 21085583 PMCID: PMC2981562 DOI: 10.1371/journal.pone.0013979] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 10/07/2010] [Indexed: 12/15/2022] Open
Abstract
Epstein-Barr virus (EBV) is able to drive the transformation of B-cells, resulting in the generation of lymphoblastoid cell lines (LCLs) in vitro. EBV nuclear proteins EBNA3A and EBNA3C are necessary for efficient transformation, while EBNA3B is dispensable. We describe a transcriptome analysis of BL31 cells infected with a series of EBNA3-knockout EBVs, including one deleted for all three EBNA3 genes. Using Affymetrix Exon 1.0 ST microarrays analysed with the MMBGX algorithm, we have identified over 1000 genes whose regulation by EBV requires one of the EBNA3s. Remarkably, a third of the genes identified require more than one EBNA3 for their regulation, predominantly EBNA3C co-operating with either EBNA3B, EBNA3A or both. The microarray was validated by real-time PCR, while ChIP analysis of a selection of co-operatively repressed promoters indicates a role for polycomb group complexes. Targets include genes involved in apoptosis, cell migration and B-cell differentiation, and show a highly significant but subtle alteration in genes involved in mitosis. In order to assess the relevance of the BL31 system to LCLs, we analysed the transcriptome of a set of EBNA3B knockout (3BKO) LCLs. Around a third of the genes whose expression level in LCLs was altered in the absence of EBNA3B were also altered in 3BKO-BL31 cell lines. Among these are TERT and TCL1A, implying that EBV-induced changes in the expression of these genes are not required for B-cell transformation. We also identify 26 genes that require both EBNA3A and EBNA3B for their regulation in LCLs. Together, this shows the complexity of the interaction between EBV and its host, whereby multiple EBNA3 proteins co-operate to modulate the behaviour of the host cell.
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Affiliation(s)
- Robert E. White
- Section of Virology, Imperial College London, London, United Kingdom
- * E-mail:
| | - Ian J. Groves
- Section of Virology, Imperial College London, London, United Kingdom
| | - Ernest Turro
- Department of Epidemiology and Biostatistics, Imperial College London, London, United Kingdom
| | - Jade Yee
- Section of Virology, Imperial College London, London, United Kingdom
| | - Elisabeth Kremmer
- Institute of Molecular Immunology Helmholtz Zentrum München - German Research Center for Environmental Health, Munich, Germany
| | - Martin J. Allday
- Section of Virology, Imperial College London, London, United Kingdom
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Klein G, Klein E, Kashuba E. Interaction of Epstein-Barr virus (EBV) with human B-lymphocytes. Biochem Biophys Res Commun 2010; 396:67-73. [PMID: 20494113 DOI: 10.1016/j.bbrc.2010.02.146] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 02/22/2010] [Indexed: 12/22/2022]
Abstract
Epstein-Barr virus, EBV, and humans have a common history that reaches back to our primate ancestors. The virus co-evolved with man and has established a largely harmless and highly complex co-existence. It is carried as silent infection by almost all human adults. A serendipitous discovery established that it is the causative agent of infectious mononucleosis. Still, EBV became known first in 1964, in a rare, geographically prevalent malignant lymphoma of B-cell origin, Burkitt lymphoma BL. Its association with a malignancy prompted intensive studies and its capacity to immortalize B-lymphocytes in vitro was soon demonstrated. Consequently EBV was classified therefore as a potentially tumorigenic virus. Despite of this property however, the virus carrier state itself does not lead to malignancies because the transformed cells are recognized by the immune response. Consequently the EBV induced proliferation of EBV carrying B-lymphocytes is manifested only under immunosuppressive conditions. The expression of EBV encoded genes is regulated by the cell phenotype. The virus genome can be found in malignancies originating from cell types other than the B-lymphocyte. Even in the EBV infected B-cell, the direct transforming capacity is restricted to a defined window of differentiation. A complex interaction between virally encoded proteins and B-cell specific cellular proteins constitute the proliferation inducing program. In this short review we touch upon aspects which are the subject of our present work. We describe the mechanisms of some of the functional interactions between EBV encoded and cellular proteins that determine the phenotype of latently infected B-cells. The growth promoting EBV encoded genes are not expressed in the virus carrying BL cells. Still, EBV seems to contribute to the etiology of this tumor by modifying events that influence cell survival and proliferation. We describe a possible growth promoting mechanism in the genesis of Burkitt lymphoma that depends on the presence of EBV.
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Affiliation(s)
- George Klein
- Karolinska Institutet, Department of Microbiology, Tumor and Cell Biology (MTC), Box 280, S17177 Stockholm, Sweden.
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Niller HH, Wolf H, Minarovits J. Regulation and dysregulation of Epstein–Barr virus latency: Implications for the development of autoimmune diseases. Autoimmunity 2009; 41:298-328. [DOI: 10.1080/08916930802024772] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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26
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Nuclear-cytoplasmic shuttling is not required for the Epstein-Barr virus EBNA-LP transcriptional coactivation function. J Virol 2009; 83:7109-16. [PMID: 19403674 DOI: 10.1128/jvi.00654-09] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) EBNA-LP is a transcriptional coactivator of EBNA2 that works though interaction with the promyelocytic leukemia nuclear-body-associated protein Sp100A. EBNA-LP localizes predominantly in the nucleus through the action of nuclear localization signals in the repeated regions of the protein. EBNA-LP has also been detected in the cytoplasm, and a previous study suggested that some of the EBNA-LP coactivation function is mediated by relocalizing histone deacetylase 4 (HDAC4) from the nucleus to the cytoplasm. Although EBNA-LP can be found in the cytoplasm, it has no obvious nuclear export signal, and there is no direct evidence for active shuttling between these cellular compartments. Whether active shuttling between the nucleus and cytoplasm is required for coactivation remains to be clarified. To address these issues, we tested a variety of EBNA-LP isoforms and mutants for nuclear-cytoplasmic shuttling activity in an interspecies heterokaryon assay and for the ability to associate with HDAC4. EBNA-LP isoforms smaller than 42 kDa shuttle efficiently in the heterokaryon assay via a crm-1-independent mechanism. In addition, no specific EBNA-LP domain that mediates nuclear export could be identified. In contrast, an EBNA-LP 62-kDa isoform does not demonstrate detectable shuttling in the heterokaryon assay yet still coactivates EBNA2 similarly to the smaller EBNA-LP isoforms. All of the EBNA-LP mutants tested, including the coactivation-deficient DeltaCR3 mutant and the nonshuttling 62-kDa isoform, were capable of associating with HDAC4. Taken together, our results suggest that simple diffusion may account for the nuclear export observed with smaller isoforms of EBNA-LP, that nuclear-cytoplasmic shuttling is not required for efficient EBNA-LP coactivation function, and that competence for HDAC4 association is not sufficient to mediate nuclear-cytoplasmic shuttling or EBNA-LP coactivation in the absence of a functional interaction with Sp100A.
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Abstract
A bioinformatic analysis identified two putative NF-kappaB binding sites in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) promoter. The ability of p65RelA to interact with the LMP1 promoter was shown by in vitro and in vivo assays. Using an EBV-transformed lymphoblastoid cell line as a reporter system for the activity of the +40/-328 LMP1 promoter region, the functional importance of NF-kappaB and other transcription factor binding sites was demonstrated. p65RelA could also induce LMP1 expression from the EBV genome in Daudi and P3HR1 Burkitt's lymphoma cell lines. Finally, it was shown that p65RelA could cooperate with EBNA2 or the aryl hydrocarbon receptor in the transactivation of the LMP1 promoter. Our study established the importance of NF-kappaB and several cis-acting elements in the regulation of the LMP1 promoter in a latency III environment and highlighted a complex interplay between NF-kappaB and other transcription factors in this process.
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Echendu CW, Ling PD. Regulation of Sp100A subnuclear localization and transcriptional function by EBNA-LP and interferon. J Interferon Cytokine Res 2008; 28:667-78. [PMID: 18844582 PMCID: PMC2988464 DOI: 10.1089/jir.2008.0023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2008] [Accepted: 04/30/2008] [Indexed: 01/12/2023] Open
Abstract
Epstein-Barr virus (EBV) efficiently immortalizes human B cells and is associated with several human malignancies. The EBV transcriptional activating protein EBNA2 and the EBNA2 coactivator EBNA-leader protein (EBNA-LP) are important for B cell immortalization. Recent observations from our laboratory indicate that EBNA-LP coactivation function is mediated through interactions with the interferon-inducible gene (ISG) Sp100, resulting in displacement from its normal location in promyelocytic leukemia nuclear bodies (PML NBs) into the nucleoplasm. The EBNA-LP- and interferon-mediated mechanisms that regulate Sp100 subnuclear localization and transcriptional function remain undefined. To clarify these issues, we generated a panel of Sp100 mutant proteins to ascertain whether EBNA-LP induces Sp100 displacement from PML NBs by interfering with Sp100 dimerization or through other domains. In addition, we tested EBNA-LP function in interferon-treated cells. Our results indicate that Sp100 dimerization, PML NB localization, and EBNA-LP interaction domains overlap significantly. We also show that IFN-beta does not inhibit EBNA-LP coactivation function. The results suggest that EBNA-LP might play a role in EBV-evasion of IFN-mediated antiviral responses.
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Affiliation(s)
- Chisaroka W Echendu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
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Ling PD, Tan J, Sewatanon J, Peng R. Murine gammaherpesvirus 68 open reading frame 75c tegument protein induces the degradation of PML and is essential for production of infectious virus. J Virol 2008; 82:8000-12. [PMID: 18508901 PMCID: PMC2519593 DOI: 10.1128/jvi.02752-07] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Accepted: 05/19/2008] [Indexed: 01/27/2023] Open
Abstract
Promyelocytic Leukemia nuclear body (PML NB) proteins mediate an intrinsic cellular host defense response against virus infections. Herpesviruses express proteins that modulate PML or PML-associated proteins by a variety of strategies, including degradation of PML or relocalization of PML NB proteins. The consequences of PML-herpesvirus interactions during infection in vivo have yet to be investigated in detail, largely because of the species-specific tropism of many human herpesviruses. Murine gammaherpesvirus 68 (gammaHV68) is emerging as a suitable model to study basic biological questions of virus-host interactions because it naturally infects mice. Therefore, we sought to determine whether gammaHV68 targets PML NBs as part of its natural life cycle. We found that gammaHV68 induces PML degradation through a proteasome-dependent mechanism and that loss of PML results in more robust virus replication in mouse fibroblasts. Surprisingly, gammaHV68-mediated PML degradation was mediated by the virion tegument protein ORF75c, which shares homology with the cellular formylglycinamide ribotide amidotransferase enzyme. In addition, we show that ORF75c is essential for production of infectious virus. ORF75 homologs are conserved in all rhadinoviruses but so far have no assigned functions. Our studies shed light on a potential role for this unusual protein in rhadinovirus biology and suggest that gammaHV68 will be a useful model for investigation of PML-herpesvirus interactions in vivo.
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Affiliation(s)
- Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Mail Stop BCM-385, One Baylor Plaza, Houston, Texas 77030, USA.
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Forsman A, Rüetschi U, Ekholm J, Rymo L. Identification of intracellular proteins associated with the EBV-encoded nuclear antigen 5 using an efficient TAP procedure and FT-ICR mass spectrometry. J Proteome Res 2008; 7:2309-19. [PMID: 18457437 DOI: 10.1021/pr700769e] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Epstein-Barr virus nuclear antigen 5 (EBNA5) is one of the first viral proteins detected after primary EBV infection and has been shown to be required for efficient transformation of B lymphocytes. EBNA5 is a protein that has many suggested functions but the underlying biology remains to be clarified. To gain further insight into the biological roles of the proposed multifunctional EBNA5, we isolated EBNA5 containing protein complexes using a modified tandem affinity purification (TAP) method and identified the protein components by LC-MS/MS analysis of tryptic digests on a LTQ-FT-ICR mass spectrometer. The modified TAP tag contained a Protein A domain and a StrepTagII sequence separated by two Tobacco Etch Virus protease cleavage sites and was fused to the C-terminus of EBNA5. Our results confirmed the wide applicability of this two-step affinity purification strategy for purification of protein complexes in mammalian cells. A total of 147 novel putative EBNA5 interaction partners were identified, 37 of which were validated with LC-MS/MS in split-tag experiments or in co-immuno precipitates from HEK293 cell extracts. This subgroup included the Bcl2-associated Athanogene 2 (BAG2) co-chaperone involved in protein folding and renaturation, the 26S proteasome subunit 2 involved in regulation of ubiquitin/proteasome protein degradation, and the heterogeneous ribonucleoprotein M (hnRNP M) involved in pre-mRNA processing. These EBNA5 interactors were further verified by co-immunoprecipitations from cell extracts of three EBV-positive lymphoblastoid lines. The combination of the Hsp70, Hsc70, BAG2 and 26S proteasome subunit 2 interactors suggests that EBNA5 might have a functional relationship with protein quality control systems that recognize proteins with abnormal structures and either refold them to normal conformation or target them for degradation. Our study also confirms previously identified interactors including HA95, Hsp70, Hsc70, Hsp27, HAX-1, Prolyl 4-hydroxylase, S3a, and alpha- and beta-tubulin.
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Affiliation(s)
- Alma Forsman
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
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Garibal J, Hollville E, Bell AI, Kelly GL, Renouf B, Kawaguchi Y, Rickinson AB, Wiels J. Truncated form of the Epstein-Barr virus protein EBNA-LP protects against caspase-dependent apoptosis by inhibiting protein phosphatase 2A. J Virol 2007; 81:7598-607. [PMID: 17494066 PMCID: PMC1933342 DOI: 10.1128/jvi.02435-06] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 05/03/2007] [Indexed: 12/31/2022] Open
Abstract
The Epstein-Barr virus (EBV)-encoded leader protein, EBNA-LP, strongly activates the EBNA2-mediated transcriptional activation of cellular and viral genes and is therefore important for EBV-induced B-cell transformation. However, a truncated form of EBNA-LP is produced in cells infected with variant EBV strains lacking EBNA2 due to a genetic deletion. The function of this truncated form is unknown. We show here that some Burkitt's lymphoma cells harboring defective EBV strains are specifically resistant to the caspase-dependent apoptosis induced by verotoxin 1 (VT-1) or staurosporine. These cells produced low-molecular-weight Y1Y2-truncated isoforms of EBNA-LP, which were partly localized in the cytoplasm. The transfection of sensitive cells with constructs encoding truncated EBNA-LP isoforms, but not full-length EBNA-LP, induced resistance to caspase-mediated apoptosis. Furthermore, VT-1 induced protein phosphatase 2A (PP2A) activation in sensitive cells but not in resistant cells, in which the truncated EBNA-LP interacted with this protein. Thus, the resistance to apoptosis observed in cells harboring defective EBV strains most probably results from the inactivation of PP2A via interactions with low-molecular-weight Y1Y2-truncated EBNA-LP isoforms.
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Affiliation(s)
- Julie Garibal
- UMR 8126 CNRS, University Paris-Sud, Institut Gustave Roussy, Rue Camille Desmoulins, 94805 Villejuif cedex, France
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32
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Peng CW, Zhao B, Chen HC, Chou ML, Lai CY, Lin SZ, Hsu HY, Kieff E. Hsp72 up-regulates Epstein-Barr virus EBNALP coactivation with EBNA2. Blood 2007; 109:5447-54. [PMID: 17341665 PMCID: PMC1890828 DOI: 10.1182/blood-2006-08-040634] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The Epstein-Barr virus (EBV) transcriptional coactivator EBNALP specifically associates and colocalizes with Hsp72 in lymphoblastoid cell lines. We now find that overexpression of Hsp72 more than doubled EBNALP coactivation with EBNA2 of a transfected EBV LMP1 promoter in B lymphoblasts, did not affect EBNA2 or EBNALP protein levels, and strongly up-regulated EBNA2 and EBNALP coactivation of LMP1 protein expression from the endogenous EBV genome in latency I infected Akata cells. The Hsp72 ATP, protein binding, and the C-terminal regulatory domains were required for full activity. An EBNALP deletion mutant, EBNALPd45, which does not associate with Hsp72, coactivated with EBNA2, but was not affected by Hsp72 overexpression, despite Hsp72 up-regulation of wild-type EBNALP coactivation with EBNA2 at all levels of EBNALP expression, indicating the importance of Hsp72 association with EBNALP for Hsp72 up-regulation of coactivation. Of importance, a 90% RNAi knockdown of Hsp72 reduced EBNALP coactivation with EBNA2 of transfected EBV LMP1 and Cp promoters by approximately 50%. Overexpression of the Hsp72 C-terminal interacting and regulatory protein, CHIP, strongly down-regulated EBNALP coactivation, independently of CHIP ubiquitin ligase activity. CHIP effects were Hsp72 dependent, indicating a background downmodulating role for CHIP in Hsp72 augmentation of EBNA2 and EBNALP coactivation. Based on these and other cited data, we favor a model in which Hsp72 chaperones EBNALP shuttling of repressors from EBNA2-enhanced promoters.
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Affiliation(s)
- Chih-Wen Peng
- Department of Life Science and Gene Therapy Division, Tzu-Chi University and Hospital, Hualien, Taiwan
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Abstract
EBV-associated malignancies remain a considerable problem in HIV-infected individuals, even in the era of HAART. Although EBV is a common factor, each disease has a unique pathogenesis. Study of these diseases reveals the viral proteins expressed in the malignancies that might contribute to the development of the disease as well as the molecular basis for pathogenesis. It is likely that this knowledge will contribute to the development of novel therapeutics that will result in more favorable outcomes in the future.
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Affiliation(s)
- Scott M Long
- Department of Biochemistry, St.Jude Children's Research Hospital, Memphis, TN, USA
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Jiménez-Ramírez C, Brooks AJ, Forshell LP, Yakimchuk K, Zhao B, Fulgham TZ, Sample CE. Epstein-Barr virus EBNA-3C is targeted to and regulates expression from the bidirectional LMP-1/2B promoter. J Virol 2006; 80:11200-8. [PMID: 16956945 PMCID: PMC1642179 DOI: 10.1128/jvi.00897-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Accepted: 08/24/2006] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) is essential for EBV-mediated immortalization of human B lymphocytes and regulates both the cell cycle and transcription. Transient reporter gene assays have implicated a pivotal role for EBNA-3C in the regulation of transcription of the majority of latency-associated genes expressed during the EBV growth program, including the viral oncoprotein LMP-1. To examine the regulation of latency gene expression by EBNA-3C, we generated an EBV-positive cell line that inducibly expresses EBNA-3C. This cell line allowed us to examine expression from the endogenous latency gene promoters in the context of an actual latent infection and the presence of other EBNA proteins, in particular EBNA-2, which is presumed to coregulate transcription with EBNA-3C. EBNA-3C induced the expression of both LMP-1 and LMP-2B mRNAs from the bidirectional LMP-1/LMP-2B promoter. In contrast, no effect was seen on expression from the common EBNA promoter Cp, which is responsive to EBNA-3C in reporter assays. Activation of LMP expression was not the consequence of increases in EBNA-2, PU.1 or Spi-B transcription factors, all of which are believed to be critical for activation of LMP-1. Chromatin immunoprecipitation assays furthermore indicated that EBNA-3C is present at the bidirectional LMP-1/LMP-2B promoter. These results indicate that EBNA-3C directly activates the expression of LMP-1 and LMP-2B but is unlikely to significantly regulate EBNA expression via Cp under normal growth conditions.
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35
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Law AHY, Lee DCW, Cheung BKW, Yim HCH, Lau ASY. Role for nonstructural protein 1 of severe acute respiratory syndrome coronavirus in chemokine dysregulation. J Virol 2006; 81:416-22. [PMID: 17035307 PMCID: PMC1797241 DOI: 10.1128/jvi.02336-05] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Severe acute respiratory syndrome (SARS) is an emerging infectious disease caused by a novel coronavirus. Since its associated morbidity and mortality have been postulated to be due to immune dysregulation, we investigated which of the viral proteins is responsible for chemokine overexpression. To delineate the viral and cellular factor interactions, the role of four SARS coronavirus proteins, including nonstructural protein 1 (nsp-1), nsp-5, envelope, and membrane, were examined in terms of cytokine induction. Our results showed that the SARS coronavirus nsp-1 plays an important role in CCL5, CXCL10, and CCL3 expression in human lung epithelial cells via the activation of NF-kappaB.
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Affiliation(s)
- Anna H Y Law
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Pokfulam, Hong Kong, Special Administrative Region, China
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36
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Goormachtigh G, Ouk TS, Mougel A, Tranchand-Bunel D, Masy E, Le Clorennec C, Feuillard J, Bornkamm GW, Auriault C, Manet E, Fafeur V, Adriaenssens E, Coll J. Autoactivation of the Epstein-Barr virus oncogenic protein LMP1 during type II latency through opposite roles of the NF-kappaB and JNK signaling pathways. J Virol 2006; 80:7382-93. [PMID: 16840319 PMCID: PMC1563735 DOI: 10.1128/jvi.02052-05] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Epstein-Barr virus (EBV) is associated with several human malignancies where it expresses limited subsets of latent proteins. Of the latent proteins, latent membrane protein 1 (LMP1) is a potent transforming protein that constitutively induces multiple cell signaling pathways and contributes to EBV-associated oncogenesis. Regulation of LMP1 expression has been extensively described during the type III latency of EBV. Nevertheless, in the majority of EBV-associated tumors, the virus is commonly found to display a type II latency program in which it is still unknown which viral or cellular protein is really involved in maintaining LMP1 expression. Here, we demonstrate that LMP1 activates its own promoter pLMP1 through the JNK signaling pathway emerging from the TES2 domain. Our results also reveal that this activation is tightly controlled by LMP1, since pLMP1 is inhibited by LMP1-activated NF-kappaB signaling pathway. By using our physiological models of EBV-infected cells displaying type II latency as well as lymphoblastoid cell lines expressing a type III latency, we also demonstrate that this balanced autoregulation of LMP1 is shared by both latency programs. Finally, we show that this autoactivation is the most important mechanism to maintain LMP1 expression during the type II latency program of EBV.
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Affiliation(s)
- Gautier Goormachtigh
- CNRS UMR 8527, Institut de Biologie de Lille (IBL), 1 rue du Pr. Calmette, 59021 Lille Cedex, France
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Reisinger J, Rumpler S, Lion T, Ambros PF. Visualization of episomal and integrated Epstein-Barr virus DNA by fiber fluorescencein situ hybridization. Int J Cancer 2006; 118:1603-8. [PMID: 16217752 DOI: 10.1002/ijc.21498] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
For many Epstein-Barr virus (EBV)-associated malignancies, it is still a matter of controversy whether infected cells harbor episomal or chromosomally integrated EBV genomes or both. It is well established that the expression of EBV genes per se carries oncogenic potential, but the discrimination between episomal and integrated forms is of great relevance because integration events can contribute to the oncogenic properties of EBV, whereas host cells that exclusively harbor viral episomes may not carry the risks mediated by chromosomal integration. This notion prompted us to establish a reliable technique that not only allows to unequivocally discriminate episomal from integrated EBV DNA, but also provides detailed insights into the genomic organization of the virus. Here, we show that dynamic molecular combing of host cell DNA combined with fluorescence in situ hybridization (FISH) using EBV-specific DNA probes facilitate unambiguous discrimination of episomal from integrated viral DNA. Furthermore, the detection of highly elongated internal repeat 1 (IR1) sequences provides evidence that this method permits detection of major genomic alterations within the EBV genome. Thus, fiber FISH may also provide valuable insights into the genomic organization of viral genomes other than EBV.
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Affiliation(s)
- Jürgen Reisinger
- Children's Cancer Research Institute, St. Anna Kinderspital, Kinderspitalgasse 6, A-1090 Vienna, Austria
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38
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Shaku F, Matsuda G, Furuya R, Kamagata C, Igarashi M, Tanaka M, Kanamori M, Nishiyama Y, Yamamoto N, Kawaguchi Y. Development of a monoclonal antibody against Epstein-Barr virus nuclear antigen leader protein (EBNA-LP) that can detect EBNA-LP expressed in P3HR1 cells. Microbiol Immunol 2005; 49:477-83. [PMID: 15905610 DOI: 10.1111/j.1348-0421.2005.tb03743.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mouse monoclonal antibody, LP4D3, was raised against purified Epstein-Barr virus nuclear antigen leader protein (EBNA-LP) fused to glutathione-S-transferase. The antibody detected endogenous and exogenous EBNA-LP in immunoblotting, immunofluorescence and immunoprecipitation assays, and the epitope of the antibody was mapped in the W2 domain of EBNA-LP. While another monoclonal antibody to EBNA-LP, JF186, which is widely used for analyses of the viral protein, did not react with truncated forms of EBNA-LP expressed in P3HR1 cells, as reported earlier, the LP4D3 antibody did. The LP4D3 antibody will be a useful tool for further studies of EBNA-LP, especially investigations into the phenotypes of mutant EBNA-LP expressed in P3HR1 cells.
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Affiliation(s)
- Fumio Shaku
- Department of Cell Regulation, Medical Research Institute, Tokyo, Japan
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39
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Ling PD, Peng RS, Nakajima A, Yu JH, Tan J, Moses SM, Yang WH, Zhao B, Kieff E, Bloch KD, Bloch DB. Mediation of Epstein-Barr virus EBNA-LP transcriptional coactivation by Sp100. EMBO J 2005; 24:3565-75. [PMID: 16177824 PMCID: PMC1276704 DOI: 10.1038/sj.emboj.7600820] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 08/25/2005] [Indexed: 12/15/2022] Open
Abstract
The Epstein-Barr virus (EBV) EBNA-LP protein is important for EBV-mediated B-cell immortalization and is a potent gene-specific coactivator of the viral transcriptional activator, EBNA2. The mechanism(s) by which EBNA-LP functions as a coactivator remains an important question in the biology of EBV-induced B-cell immortalization. In this study, we found that EBNA-LP interacts with the promyelocytic leukemia nuclear body (PML NB)-associated protein Sp100 and displaces Sp100 and heterochromatin protein 1alpha (HP1alpha) from PML NBs. Interaction between EBNA-LP and Sp100 was mediated through conserved region 3 in EBNA-LP and the PML NB targeting domain in Sp100. Overexpression of Sp100 lacking the N-terminal PML NB targeting domain, but not a mutant form of Sp100 lacking the HP1alpha interaction domain, was sufficient to coactivate EBNA2 in a gene-specific manner independent of EBNA-LP. These findings suggest that Sp100 is a major mediator of EBNA-LP coactivation. These studies indicate that modulation of PML NB-associated proteins may be important for establishment of latent viral infections, and also identify a convenient model system to investigate the functions of Sp100.
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Affiliation(s)
- Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Rong Sheng Peng
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Ayako Nakajima
- Department of Medicine, Harvard Medical School and Center for Immunology and Inflammatory Diseases of the General Medical Services, Massachusetts General Hospital, Boston, MA, USA
| | - Jiang H Yu
- Department of Medicine, Harvard Medical School and Center for Immunology and Inflammatory Diseases of the General Medical Services, Massachusetts General Hospital, Boston, MA, USA
| | - Jie Tan
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Stephanie M Moses
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Wei-Hong Yang
- Department of Medicine, Harvard Medical School and Center for Immunology and Inflammatory Diseases of the General Medical Services, Massachusetts General Hospital, Boston, MA, USA
| | - Bo Zhao
- Departments of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Elliott Kieff
- Departments of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Kenneth D Bloch
- Department of Medicine, Harvard Medical School and Cardiovascular Research Center of the General Medical Services, Massachusetts General Hospital, Boston, MA, USA
| | - Donald B Bloch
- Department of Medicine, Harvard Medical School and Center for Immunology and Inflammatory Diseases of the General Medical Services, Massachusetts General Hospital, Boston, MA, USA
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40
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Maruo S, Johannsen E, Illanes D, Cooper A, Zhao B, Kieff E. Epstein-Barr virus nuclear protein 3A domains essential for growth of lymphoblasts: transcriptional regulation through RBP-Jkappa/CBF1 is critical. J Virol 2005; 79:10171-9. [PMID: 16051810 PMCID: PMC1182629 DOI: 10.1128/jvi.79.16.10171-10179.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Experimental reverse genetic replacement of Epstein-Barr virus nuclear antigen 3A (EBNA3A) with a conditional mutant EBNA3A revealed that EBNA3A is critical for continued lymphoblastoid cell (LCL) growth. Wild-type (wt) EBNA3A expressed in the LCLs specifically sustained growth under nonpermissive conditions, whereas EBNA3B or EBNA3C expression had no effect (S. Mauro, E. Johannsen, D. Illanes, A. Cooper, and E. Kieff, J. Virol. 77:10437-10447, 2003). This genetic system and related biochemical assays have now been used to discover that EBNA3A lacking amino acid residues 170 to 240 (delta170-240), TLGC202 to AAGA202, or delta300-386, which are deficient in repression of EBNA2 activation of an RBP-Jkappa/CBF1-dependent EBV Cp enhancer, are null mutations for LCL growth, whereas EBNA3A delta2-124, delta410-439, delta440-470, delta470-500, delta500-523, delta523-612, and delta620-820, which are wt in repression are wt for LCL growth. Thus, EBNA3A regulation of transcription through RBP-Jkappa/CBF1 is critical for LCL growth. EBNA3A mutants deleted of amino acid residues 240 to 300, 386 to 410, or 827 to 944 were intermediate, null, or intermediate, respectively, for LCL growth despite being wt for RBP-Jkappa association and repression. Amino acid residues 240 to 300, 386 to 410, and, particularly, C-terminal residues 827 to 944 are therefore likely to contribute to LCL growth through RBP-Jkappa-independent mechanisms.
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Affiliation(s)
- Seiji Maruo
- Department of Medicine, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
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41
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Yue W, Gershburg E, Pagano JS. Hyperphosphorylation of EBNA2 by Epstein-Barr virus protein kinase suppresses transactivation of the LMP1 promoter. J Virol 2005; 79:5880-5. [PMID: 15827205 PMCID: PMC1082719 DOI: 10.1128/jvi.79.9.5880-5885.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [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) BGLF4 gene encodes a serine/threonine protein kinase (PK) that is expressed in the cytolytic cycle. EBV nuclear antigen 2 (EBNA2) is a key latency gene essential for immortalization of B lymphocytes and transactivation of viral and cellular promoters. Here we report that EBV PK phosphorylates EBNA2 at Ser-243 and that these two proteins physically associate. PK suppresses EBNA2's ability to transactivate the LMP1 promoter, and Ser-243 of EBNA2 is involved in this suppression. Moreover, EBNA2 is hyperphosphorylated during EBV reactivation in latently infected B cells, which is associated with decreased LMP1 protein levels. This is the first report about the effect of EBV PK on the function of one of its target proteins and regulation of EBNA2 phosphorylation during the EBV lytic cycle.
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Affiliation(s)
- Wei Yue
- Department of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina, Campus Box 7295, Chapel Hill, NC 27599, USA
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42
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Peng R, Moses SC, Tan J, Kremmer E, Ling PD. The Epstein-Barr virus EBNA-LP protein preferentially coactivates EBNA2-mediated stimulation of latent membrane proteins expressed from the viral divergent promoter. J Virol 2005; 79:4492-505. [PMID: 15767449 PMCID: PMC1061541 DOI: 10.1128/jvi.79.7.4492-4505.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanistic contribution of the Epstein-Barr virus (EBV) EBNA-LP protein to B-cell immortalization remains an enigma. However, previous studies have indicated that EBNA-LP may contribute to immortalization by enhancing EBNA2-mediated transcriptional activation of the LMP-1 gene. To gain further insight into the potential role EBNA-LP has in EBV-mediated B-cell immortalization, we asked whether it is a global or gene-specific coactivator of EBNA2 and whether coactivation requires interaction between these proteins. In type I Burkitt's lymphoma cells, we found that EBNA-LP strongly coactivated EBNA2 stimulation of LMP-1 and LMP2B RNAs, which are expressed from the viral divergent promoter. Surprisingly, the viral LMP2A gene and cellular CD21 and Hes-1 genes were induced by EBNA2 but showed no further induction after EBNA-LP coexpression. We also found that EBNA-LP did not stably interact with EBNA2 in coimmunoprecipitation assays, even though the conditions were adequate to observe specific interactions between EBNA2 and its cellular cofactor, CBF1. Colocalization between EBNA2 and EBNA-LP was not detectable in EBV-transformed cell lines or transfected type I Burkitt's cells. Finally, no significant interactions between EBNA2 and EBNA-LP were found with mammalian two-hybrid assays. From this data, we conclude that EBNA-LP is not a global coactivator of EBNA2 targets, but it preferentially coactivates EBNA2 stimulation of the viral divergent promoter. While this may require specific transient interactions between these proteins that only occur in the context of the divergent promoter, our data strongly suggest that EBNA-LP also cooperates with EBNA2 through mechanisms that do not require direct or indirect complex formation between these proteins.
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Affiliation(s)
- Rongsheng Peng
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
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43
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Chang Y, Lee HH, Chang SS, Hsu TY, Wang PW, Chang YS, Takada K, Tsai CH. Induction of Epstein-Barr virus latent membrane protein 1 by a lytic transactivator Rta. J Virol 2004; 78:13028-36. [PMID: 15542654 PMCID: PMC525024 DOI: 10.1128/jvi.78.23.13028-13036.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) is a transforming protein that affects multiple cell signaling pathways and contributes to EBV-associated oncogenesis. LMP1 can be expressed in some states of EBV latency, and significant induction of full-length LMP1 is also observed frequently during virus reactivation into the lytic cycle. It is still unknown how LMP1 expression is regulated during the lytic stage and whether any EBV lytic protein is involved in the induction of LMP1. In this study, we first identified that LMP1 expression is associated with the spontaneous virus reactivation in EBV-infected 293 cells and that its expression is a downstream event of the lytic cycle. We further found that LMP1 can be induced by ectopic expression of Rta, an EBV immediate-early lytic protein. The Rta-mediated LMP1 induction is independent of another immediate-early protein, Zta. Northern blotting and reverse transcription-PCR analysis revealed that Rta upregulates LMP1 at the RNA level. Reporter gene assays further demonstrated that Rta activates both the proximal and distal promoters of the LMP1 gene in EBV-negative cells. Both the amino and carboxyl termini of the Rta protein are required for the induction of LMP1. In addition, Rta transactivates LMP1 not only in epithelial cells but also in B-lymphoid cells. This study reveals a new mechanism to upregulate LMP1 expression, expanding the knowledge of LMP1 regulation in the EBV life cycle. Considering an equivalent case of Kaposi's sarcoma-associated herpesvirus, induction of a transforming membrane protein by a key lytic transactivator during virus reactivation is likely to be a conserved event for gammaherpesviruses.
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Affiliation(s)
- Yao Chang
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Room 714, Number 1, Section 1, Jen-Ai Rd., Taipei, Taiwan
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44
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Lee JM, Lee KH, Farrell CJ, Ling PD, Kempkes B, Park JH, Hayward SD. EBNA2 is required for protection of latently Epstein-Barr virus-infected B cells against specific apoptotic stimuli. J Virol 2004; 78:12694-7. [PMID: 15507659 PMCID: PMC525073 DOI: 10.1128/jvi.78.22.12694-12697.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In addition to functioning as a transcriptional transactivator, Epstein-Barr virus EBNA2 interacts with Nur77 to protect against Nur77-mediated apoptosis. Estrogen-regulated EBNA2 in EREB2-5 cells was replaced by either EBNA2 or EBNA2 with a deletion of conserved region 4 (EBNA2DeltaCR4). Both EBNA2-converted and EBNA2DeltaCR4-converted EREB2-5 cells grew in the absence of estrogen and expressed LMP1. Treatment with tumor necrosis factor alpha did not induce apoptosis of EBNA2- or EBNA2DeltaCR4-expressing cells, but EBNA2DeltaCR4 cells were susceptible to etoposide and 5-fluorouracil, Nur77-mediated inducers of apoptosis. Thus, EBNA2 protects B cells against specific apoptotic agents against which LMP1 is not effective.
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Affiliation(s)
- Jae Myun Lee
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, School of Medicine, Bunting-Blaustein Building CRB308, 1650 Orleans Street, Baltimore, MD 21231, USA
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45
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Abstract
EBNA2 transcriptional activation and regulated EBNALP coactivation are critical for Epstein-Barr virus-infected primary B-lymphocyte growth transformation. EBNALP coactivation requires the EBNA2 acidic activation domain (E2AD); EBNALP can bind to E2AD. EBNALP has now been found to bind less well to EBNA2 amino acids 1 to 58, which has been identified to be a second transcriptional activation domain, E2AD2. E2AD2 was specifically coactivated by EBNALP. Moreover, E2AD, E2AD2, EBNA2 RG domain, and the intermediate domain between RG and E2AD had significant roles in EBNA2-mediated activation and EBNALP coactivation.
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Affiliation(s)
- Chih-Wen Peng
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital, and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
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46
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Abstract
The Notch signaling pathway influences cell fate decisions, proliferation versus differentiation and cell survival. Viruses both utilize and manipulate the differentiation state of infected cells, promote or block cell cycling and employ a variety of mechanisms to evade innate cellular anti-viral responses and promote cell survival. In light of these commonalities, it is perhaps not surprising that several viruses have tapped into the Notch pathway to advance their own life cycles. This first became apparent from studies showing targeting of Epstein-Barr virus proteins to the nuclear effector of Notch signaling CSL (CBF1/RBPJk). More recently the Kaposi's sarcoma-associated herpesvirus RTA protein has been found to bind CSL. Notch pathway interactions have also been described for adenovirus SV40 and human papilloma virus. This review focuses on the herpesvirus protein interactions with the Notch pathway and the insights that these interactions have provided.
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Affiliation(s)
- S Diane Hayward
- Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, School of Medicine, CRB 308, 1650 Orleans Street, Baltimore, MD 21231, USA.
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47
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Abstract
EBV was the first human virus to be directly implicated in carcinogenesis. It infects >90% of the world's population. Although most humans coexist with the virus without serious sequelae, a small proportion will develop tumors. Normal host populations can have vastly different susceptibility to EBV-related tumors as demonstrated by geographical and immunological variations in the prevalence of these cancers. EBV has been implicated in the pathogenesis of Burkitt's lymphoma, Hodgkin's disease, non-Hodgkin's lymphoma, nasopharyngeal carcinoma, and lymphomas, as well as leiomyosarcomas arising in immunocompromised individuals. The presence of this virus has also been associated with epithelial malignancies arising in the gastric region and the breast, although some of this work remains in dispute. EBV uses its viral proteins, the actions of which mimic several growth factors, transcription factors, and antiapoptotic factors, to usurp control of the cellular pathways that regulate diverse homeostatic cellular functions. Recent advances in antiviral therapeutics, application of monoclonal antibodies, and generation of EBV-specific CTLs are beginning to show promise in the treatment of EBV-related disorders.
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Affiliation(s)
- Matthew P Thompson
- Department of Bioimmunotherapy, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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48
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Sutkowski N, Chen G, Calderon G, Huber BT. Epstein-Barr virus latent membrane protein LMP-2A is sufficient for transactivation of the human endogenous retrovirus HERV-K18 superantigen. J Virol 2004; 78:7852-60. [PMID: 15220463 PMCID: PMC434102 DOI: 10.1128/jvi.78.14.7852-7860.2004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Superantigens are microbial proteins that strongly stimulate T cells. We described previously that the Epstein-Barr virus (EBV) transactivates a superantigen encoded by the human endogenous retrovirus, HERV-K18. We now report that the transactivation is dependent upon the EBV latent cycle proteins. Moreover, LMP-2A is sufficient for induction of HERV-K18 superantigen activity.
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Affiliation(s)
- Natalie Sutkowski
- Department of Pathology, Tufts University School of Medicine, Boston, MA 02111, USA
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49
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Kanamori M, Watanabe S, Honma R, Kuroda M, Imai S, Takada K, Yamamoto N, Nishiyama Y, Kawaguchi Y. Epstein-Barr virus nuclear antigen leader protein induces expression of thymus- and activation-regulated chemokine in B cells. J Virol 2004; 78:3984-93. [PMID: 15047814 PMCID: PMC374277 DOI: 10.1128/jvi.78.8.3984-3993.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) plays a critical role in transformation of primary B lymphocytes to continuously proliferating lymphoblastoid cell lines (LCLs). To identify cellular genes in B cells whose expression is regulated by EBNA-LP, we performed microarray expression profiling on an EBV-negative human B-cell line, BJAB cells, that were transduced by a retroviral vector expressing the EBV EBNA-LP (BJAB-LP cells) and on BJAB cells that were transduced with a control vector (BJAB-vec cells). Microarray analysis led to the identification of a cellular gene encoding the CC chemokine TARC as a novel target gene that was induced by EBNA-LP. The levels of TARC mRNA expression and TARC secretion were significantly up-regulated in BJAB-LP compared with BJAB-vec cells. Induction of TARC was also observed when a subline of BJAB cells was converted by a recombinant EBV. Among the EBV-infected B-cell lines with the latency III phenotype that were tested, the LCLs especially secreted significantly high levels of TARC. The level of TARC secretion appeared to correlate with the level of full-length EBNA-LP expression. These results indicate that EBV infection induces TARC expression in B cells and that EBNA-LP is one of the viral gene products responsible for the induction.
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Affiliation(s)
- Mikiko Kanamori
- Department of Virology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya 466-8550, Japan
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50
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Gordadze AV, Onunwor CW, Peng R, Poston D, Kremmer E, Ling PD. EBNA2 amino acids 3 to 30 are required for induction of LMP-1 and immortalization maintenance. J Virol 2004; 78:3919-29. [PMID: 15047808 PMCID: PMC374290 DOI: 10.1128/jvi.78.8.3919-3929.2004] [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: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2), a direct transcriptional activator of viral and cellular genes, is required for EBV-induced B-cell transformation. The functional role of conserved regions within the amino terminus of the protein preceding the poly-proline region has yet to be fully characterized. Thus, we tested whether the EBNA2 amino-terminal 30 amino acid residues, containing evolutionarily conserved region 1, are required for stimulating viral and cellular gene expression necessary for B-cell transformation in a viral transcomplementation assay. We found that these residues are required for its ability to induce LMP-1 expression in lymphoblastoid cell lines (LCLs), to stimulate LMP-1 promoter reporter plasmids in transient-cotransfection assays, and to rescue LCL growth following inactivation of endogenous wild-type EBNA2 protein. Deletion of amino acid residues 3 to 30 also impaired its ability to self-associate in coimmunoprecipitation assays. These data indicate that EBNA2 residues 3 to 30 comprise an essential domain required for induction of LMP-1 expression and, consequently, for maintenance of the immortalized phenotype of LCLs. The ability to self-associate into dimers or multimers conferred by this domain may be an important mechanism for these effects.
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Affiliation(s)
- Alexey V Gordadze
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
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