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Dai YC, Yeh SY, Cheng YY, Huang WH, Liou GG, Yang TY, Chang CY, Fang TF, Chang CW, Su MT, Lee CP, Chen MR. BGLF4 kinase regulates the formation of the EBV cytoplasmic assembly compartment and the recruitment of cellular IQGAP1 for virion release. J Virol 2024; 98:e0189923. [PMID: 38294245 PMCID: PMC10878254 DOI: 10.1128/jvi.01899-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 12/26/2023] [Indexed: 02/01/2024] Open
Abstract
After Epstein-Barr virus (EBV) genome replication and encapsidation in the nucleus, nucleocapsids are translocated into the cytoplasm for subsequent tegumentation and maturation. The EBV BGLF4 kinase, which induces partial disassembly of the nuclear lamina, and the nuclear egress complex BFRF1/BFLF2 coordinately facilitate the nuclear egress of nucleocapsids. Here, we demonstrate that within EBV reactivated epithelial cells, viral capsids, tegument proteins, and glycoproteins are clustered in the juxtanuclear concave region, accompanied by redistributed cytoplasmic organelles and the cytoskeleton regulator IQ-domain GTPase-activation protein 1 (IQGAP1), close to the microtubule-organizing center (MTOC). The assembly compartment (AC) structure was diminished in BGLF4-knockdown TW01-EBV cells and BGLF4-knockout bacmid-carrying TW01 cells, suggesting that the formation of AC structure is BGLF4-dependent. Notably, glycoprotein gp350/220 was observed by confocal imaging to be distributed in the perinuclear concave region and surrounded by the endoplasmic reticulum (ER) membrane marker calnexin, indicating that the AC may be located within a globular structure derived from ER membranes, adjacent to the outer nuclear membrane. Moreover, the viral capsid protein BcLF1 and tegument protein BBLF1 were co-localized with IQGAP1 near the cytoplasmic membrane in the late stage of replication. Knockdown of IQGAP1 did not affect the AC formation but decreased virion release from both TW01-EBV and Akata+ cells, suggesting IQGAP1-mediated trafficking regulates EBV virion release. The data presented here show that BGLF4 is required for cytoskeletal rearrangement, coordination with the redistribution of cytoplasmic organelles and IQGAP1 for virus maturation, and subsequent IQGAP1-dependent virion release.IMPORTANCEEBV genome is replicated and encapsidated in the nucleus, and the resultant nucleocapsids are translocated to the cytoplasm for subsequent virion maturation. We show that a cytoplasmic AC, containing viral proteins, markers of the endoplasmic reticulum, Golgi, and endosomes, is formed in the juxtanuclear region of epithelial and B cells during EBV reactivation. The viral BGLF4 kinase contributes to the formation of the AC. The cellular protein IQGAP1 is also recruited to the AC and partially co-localizes with the virus capsid protein BcLF1 and tegument protein BBLF1 in EBV-reactivated cells, dependent on the BGLF4-induced cytoskeletal rearrangement. In addition, virion release was attenuated in IQGAP1-knockdown epithelial and B cells after reactivation, suggesting that IQGAP1-mediated trafficking may regulate the efficiency of virus maturation and release.
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Affiliation(s)
- Yu-Ching Dai
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Szu-Yun Yeh
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Ying Cheng
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Han Huang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Gunn-Guang Liou
- Office of Research and Development, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Tsung-Yu Yang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chao-Yuan Chang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Tien-Fang Fang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chou-Wei Chang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Mei-Tzu Su
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chung-Pei Lee
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Mei-Ru Chen
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Chao TY, Cheng YY, Wang ZY, Fang TF, Chang YR, Fuh CS, Su MT, Su YW, Hsu PH, Su YC, Chang YC, Lee TY, Chou WH, Middeldorp JM, Saraste J, Chen MR. Subcellular Distribution of BALF2 and the Role of Rab1 in the Formation of Epstein-Barr Virus Cytoplasmic Assembly Compartment and Virion Release. Microbiol Spectr 2023; 11:e0436922. [PMID: 36602343 PMCID: PMC9927466 DOI: 10.1128/spectrum.04369-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 12/06/2022] [Indexed: 01/06/2023] Open
Abstract
Epstein-Barr virus (EBV) replicates its genome in the nucleus and undergoes tegumentation and envelopment in the cytoplasm. We are interested in how the single-stranded DNA binding protein BALF2, which executes its function and distributes predominantly in the nucleus, is packaged into the tegument of virions. At the mid-stage of virus replication in epithelial TW01-EBV cells, a small pool of BALF2 colocalizes with tegument protein BBLF1, BGLF4 protein kinase, and the cis-Golgi marker GM130 at the perinuclear viral assembly compartment (AC). A possible nuclear localization signal (NLS) between amino acids 1100 and 1128 (C29), which contains positive charged amino acid 1113RRKRR1117, is able to promote yellow fluorescent protein (YFP)-LacZ into the nucleus. In addition, BALF2 interacts with the nucleocapsid-associated protein BVRF1, suggesting that BALF2 may be transported into the cytoplasm with nucleocapsids in a nuclear egress complex (NEC)-dependent manner. A group of proteins involved in intracellular transport were identified to interact with BALF2 in a proteomic analysis. Among them, the small GTPase Rab1A functioning in bi-directional trafficking at the ER-Golgi interface is also a tegument component. In reactivated TW01-EBV cells, BALF2 colocalizes with Rab1A in the cytoplasmic AC. Expression of dominant-negative GFP-Rab1A(N124I) diminished the accumulation of BALF2 in the AC, coupling with attenuation of gp350/220 glycosylation. Virion release was significantly downregulated by expressing dominant-negative GFP-Rab1A(N124I). Overall, the subcellular distribution of BALF2 is regulated through its complex interaction with various proteins. Rab1 activity is required for proper gp350/220 glycosylation and the maturation of EBV. IMPORTANCE Upon EBV lytic reactivation, the virus-encoded DNA replication machinery functions in the nucleus, while the newly synthesized DNA is encapsidated and transported to the cytoplasm for final virus assembly. The single-stranded DNA binding protein BALF2 executing functions within the nucleus was also identified in the tegument layer of mature virions. Here, we studied the functional domain of BALF2 that contributes to the nuclear targeting and used a proteomic approach to identify novel BALF2-interacting cellular proteins that may contribute to virion morphogenesis. The GTPase Rab1, a master regulator of anterograde and retrograde endoplasmic reticulum (ER)-Golgi trafficking, colocalizes with BALF2 in the juxtanuclear concave region at the midstage of EBV reactivation. Rab1 activity is required for BALF2 targeting to the cytoplasmic assembly compartment (AC) and for gp350/220 targeting to cis-Golgi for proper glycosylation and virion release. Our study hints that EBV hijacks the bi-directional ER-Golgi trafficking machinery to complete virus assembly.
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Affiliation(s)
- Tsung-Yu Chao
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Yi-Ying Cheng
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Zi-Yun Wang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Tien-Fang Fang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Yu-Ruei Chang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Chi-Shane Fuh
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Mei-Tzu Su
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Yuan-Wei Su
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Pang-Hung Hsu
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan
| | - Yu-Chen Su
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Yu-Ching Chang
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Ting-Yau Lee
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Wei-Han Chou
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
| | - Jaap M. Middeldorp
- VU University Medical Center, Department of Pathology, Cancer Center Amsterdam, Amsterdam, The Netherlands
| | - Jaakko Saraste
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Bergen, Norway
| | - Mei-Ru Chen
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Tipei, Taiwan
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3
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Gonnella R, Dimarco M, Farina GA, Santarelli R, Valia S, Faggioni A, Angeloni A, Cirone M, Farina A. BFRF1 protein is involved in EBV-mediated autophagy manipulation. Microbes Infect 2020; 22:585-591. [PMID: 32882412 DOI: 10.1016/j.micinf.2020.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/06/2020] [Accepted: 08/25/2020] [Indexed: 12/28/2022]
Abstract
Viral egress and autophagy are two mechanisms that seem to be strictly connected in Herpesviruses's biology. Several data suggest that the autophagic machinery facilitates the egress of viral capsids and thus the production of new infectious particles. In the Herpesvirus family, viral nuclear egress is controlled and organized by a well conserved group of proteins named Nuclear Egress Complex (NEC). In the case of EBV, NEC is composed by BFRF1 and BFLF2 proteins, although the alterations of the nuclear host cell architecture are mainly driven by BFRF1, a multifunctional viral protein anchored to the inner nuclear membrane of the host cell. BFRF1 shares a peculiar distribution with several nuclear components and with them it strictly interacts. In this study, we investigated the possible role of BFRF1 in manipulating autophagy, pathway that possibly originates from nucleus, regulating the interplay between autophagy and viral egress.
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Affiliation(s)
- Roberta Gonnella
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy
| | - Marzia Dimarco
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy
| | | | - Roberta Santarelli
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy
| | - Sandro Valia
- Dep. Molecular Medicine University of Rome "La Sapienza", Italy
| | - Alberto Faggioni
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy
| | - Antonio Angeloni
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy
| | - Mara Cirone
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy
| | - Antonella Farina
- Dep. Experimental Medicine University of Rome "La Sapienza", Laboratory Affiliated to Istituto Pasteur Italia fondazione Cenci-Bolognetti, Italy; Dep. Molecular Medicine University of Rome "La Sapienza", Italy; Boston University School of Medicine, Boston, MA, USA.
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Oncogenic Properties of the EBV ZEBRA Protein. Cancers (Basel) 2020; 12:cancers12061479. [PMID: 32517128 PMCID: PMC7352903 DOI: 10.3390/cancers12061479] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022] Open
Abstract
Epstein Barr Virus (EBV) is one of the most common human herpesviruses. After primary infection, it can persist in the host throughout their lifetime in a latent form, from which it can reactivate following specific stimuli. EBV reactivation is triggered by transcriptional transactivator proteins ZEBRA (also known as Z, EB-1, Zta or BZLF1) and RTA (also known as BRLF1). Here we discuss the structural and functional features of ZEBRA, its role in oncogenesis and its possible implication as a prognostic or diagnostic marker. Modulation of host gene expression by ZEBRA can deregulate the immune surveillance, allow the immune escape, and favor tumor progression. It also interacts with host proteins, thereby modifying their functions. ZEBRA is released into the bloodstream by infected cells and can potentially penetrate any cell through its cell-penetrating domain; therefore, it can also change the fate of non-infected cells. The features of ZEBRA described in this review outline its importance in EBV-related malignancies.
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5
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Chen C, Feng P, Slots J. Herpesvirus-bacteria synergistic interaction in periodontitis. Periodontol 2000 2020; 82:42-64. [PMID: 31850623 DOI: 10.1111/prd.12311] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The etiopathogenesis of severe periodontitis includes herpesvirus-bacteria coinfection. This article evaluates the pathogenicity of herpesviruses (cytomegalovirus and Epstein-Barr virus) and periodontopathic bacteria (Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis) and coinfection of these infectious agents in the initiation and progression of periodontitis. Cytomegalovirus and A. actinomycetemcomitans/P. gingivalis exercise synergistic pathogenicity in the development of localized ("aggressive") juvenile periodontitis. Cytomegalovirus and Epstein-Barr virus are associated with P. gingivalis in adult types of periodontitis. Periodontal herpesviruses that enter the general circulation may also contribute to disease development in various organ systems. A 2-way interaction is likely to occur between periodontal herpesviruses and periodontopathic bacteria, with herpesviruses promoting bacterial upgrowth, and bacterial factors reactivating latent herpesviruses. Bacterial-induced gingivitis may facilitate herpesvirus colonization of the periodontium, and herpesvirus infections may impede the antibacterial host defense and alter periodontal cells to predispose for bacterial adherence and invasion. Herpesvirus-bacteria synergistic interactions, are likely to comprise an important pathogenic determinant of aggressive periodontitis. However, mechanistic investigations into the molecular and cellular interaction between periodontal herpesviruses and bacteria are still scarce. Herpesvirus-bacteria coinfection studies may yield significant new discoveries of pathogenic determinants, and drug and vaccine targets to minimize or prevent periodontitis and periodontitis-related systemic diseases.
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Affiliation(s)
- Casey Chen
- Division of Periodontology, Diagnostic Sciences & Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA
| | - Pinghui Feng
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA
| | - Jørgen Slots
- Division of Periodontology, Diagnostic Sciences & Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA
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6
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Cao P, Zhang M, Wang L, Sai B, Tang J, Luo Z, Shuai C, Zhang L, Li Z, Wang Y, Li G, Xiang J. miR-18a reactivates the Epstein-Barr virus through defective DNA damage response and promotes genomic instability in EBV-associated lymphomas. BMC Cancer 2018; 18:1293. [PMID: 30594162 PMCID: PMC6311029 DOI: 10.1186/s12885-018-5205-9] [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: 11/13/2017] [Accepted: 12/10/2018] [Indexed: 12/13/2022] Open
Abstract
Background The Epstein-Barr virus (EBV) is closely associated with several types of malignancies. EBV is normally present in the latent state in the peripheral blood B cell compartment. The EBV latent-to-lytic switch is required for virus spread and virus-induced carinogenesis. Immunosuppression or DNA damage can induce the reactivation of EBV replication. EBV alone is rarely sufficient to cause cancer. In this study, we investigated the roles of host microRNAs and environmental factors, such as DNA-damage agents, in EBV reactivation and its association with lymphomagenesis. Methods We first analyzed the publicly available microRNA array data containing 45 diffuse large B-cell lymphoma patients and 10 control lymph nodes or B cells with or without EBV infection. In situ hybridization for miR-18a and immunohistochemitry were performed to evaluate the correlation between the expression of miR-18a and nuclear EBV protein EBNA1 in lymphoid neoplasm. The proliferative effects of miR-18a were investigated in EBV-positive or –negative lymphoid neoplasm cell lines. EBV viral load was measured by a quantitative real-time EBV PCR and FISH assay. The genomic instability was evaluated by CGH-array. Results In this study, we analyzed the publicly available microRNA array data and observed that the expression of the miR-17-92 cluster was associated with EBV status. In situ hybridization for miR-18a, which is a member of the miR-17-92 cluster, showed a significant upregulation in lymphoma samples. miR-18a, which shares the homolog sequence with EBV-encoded BART-5, promoted the proliferation of lymphoma cells in an EBV status-dependent manner. The DNA-damaging agent UV or hypoxia stress induced EBV activation, and miR-18a contributed to DNA damaging-induced EBV reactivation. In contrast to the promoting effect of ATM on the lytic EBV reactivation in normoxia, ATM inhibited lytic EBV gene expression and decreased the EBV viral load in the prescence of hypoxia-induced DNA damage. miR-18a reactivated EBV through inhibiting the ATM-mediated DNA damage response (DDR) and caused genomic instability. Conclusions Taken together, these results indicate that DNA-damaging agents and host microRNAs play roles in EBV reactivation. Our study supported the interplay between host cell DDR, environmental genotoxic stress and EBV. Electronic supplementary material The online version of this article (10.1186/s12885-018-5205-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pengfei Cao
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China
| | - Meili Zhang
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China.,People's Hospital of Dezhou, Dezhou, 253045, Shandong, China
| | - Lujuan Wang
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China.,Hunan Key Laboratory of Nonresolving inflammation and Cancer, Desease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Buqing Sai
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China.,Hunan Key Laboratory of Nonresolving inflammation and Cancer, Desease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Jiuqi Tang
- Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China
| | - Zhaohui Luo
- Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China
| | - Cijun Shuai
- State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha, 410083, Hunan, China
| | - Liyang Zhang
- People's Hospital of Dezhou, Dezhou, 253045, Shandong, China
| | - Zheng Li
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China.,Hunan Key Laboratory of Nonresolving inflammation and Cancer, Desease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Yanjin Wang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China
| | - Guiyuan Li
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China.,Hunan Key Laboratory of Nonresolving inflammation and Cancer, Desease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Juanjuan Xiang
- Key Laboratory of Carcinogenesis of Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410078, Hunan, China. .,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, 410078, Hunan, China. .,Hunan Key Laboratory of Nonresolving inflammation and Cancer, Desease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China.
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Mutant Cellular AP-1 Proteins Promote Expression of a Subset of Epstein-Barr Virus Late Genes in the Absence of Lytic Viral DNA Replication. J Virol 2018; 92:JVI.01062-18. [PMID: 30021895 DOI: 10.1128/jvi.01062-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 07/10/2018] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) ZEBRA protein activates the EBV lytic cycle. Cellular AP-1 proteins with alanine-to-serine [AP-1(A/S)] substitutions homologous to ZEBRA(S186) assume some functions of EBV ZEBRA. These AP-1(A/S) mutants bind methylated EBV DNA and activate expression of some EBV genes. Here, we compare expression of 67 viral genes induced by ZEBRA versus expression induced by AP-1(A/S) proteins. AP-1(A/S) activated 24 genes to high levels and 15 genes to intermediate levels; activation of 28 genes by AP-1(A/S) was severely impaired. We show that AP-1(A/S) proteins are defective at stimulating viral lytic DNA replication. The impairment of expression of many late genes compared to that of ZEBRA is likely due to the inability of AP-1(A/S) proteins to promote viral DNA replication. However, even in the absence of detectable viral DNA replication, AP-1(A/S) proteins stimulated expression of a subgroup of late genes that encode viral structural proteins and immune modulators. In response to ZEBRA, expression of this subgroup of late genes was inhibited by phosphonoacetic acid (PAA), which is a potent viral replication inhibitor. However, when the lytic cycle was activated by AP-1(A/S), PAA did not reduce expression of this subgroup of late genes. We also provide genetic evidence, using the BMRF1 knockout bacmid, that these genes are true late genes in response to ZEBRA. AP-1(A/S) binds to the promoter region of at least one of these late genes, BDLF3, encoding an immune modulator.IMPORTANCE Mutant c-Jun and c-Fos proteins selectively activate expression of EBV lytic genes, including a subgroup of viral late genes, in the absence of viral DNA replication. These findings indicate that newly synthesized viral DNA is not invariably required for viral late gene expression. While viral DNA replication may be obligatory for late gene expression driven by viral transcription factors, it does not limit the ability of cellular transcription factors to activate expression of some viral late genes. Our results show that expression of all late genes may not be strictly dependent on viral lytic DNA replication. The c-Fos A151S mutation has been identified in a human cancer. c-Fos A151S in combination with wild-type c-Jun activates the EBV lytic cycle. Our data provide proof of principle that mutant cellular transcription factors could cause aberrant regulation of viral lytic cycle gene expression and play important roles in EBV-associated diseases.
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8
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Murer A, McHugh D, Caduff N, Kalchschmidt J, Barros M, Zbinden A, Capaul R, Niedobitek G, Allday M, Chijioke O, Münz C. EBV persistence without its EBNA3A and 3C oncogenes in vivo. PLoS Pathog 2018; 14:e1007039. [PMID: 29709016 PMCID: PMC5945050 DOI: 10.1371/journal.ppat.1007039] [Citation(s) in RCA: 26] [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: 02/03/2018] [Revised: 05/10/2018] [Accepted: 04/17/2018] [Indexed: 01/17/2023] Open
Abstract
The oncogenic Epstein Barr virus (EBV) infects the majority of the human population and usually persists within its host for life without symptoms. The EBV oncoproteins nuclear antigen 3A (EBNA3A) and 3C (EBNA3C) are required for B cell transformation in vitro and are expressed in EBV associated immunoblastic lymphomas in vivo. In order to address the necessity of EBNA3A and EBNA3C for persistent EBV infection in vivo, we infected NOD-scid γcnull mice with reconstituted human immune system components (huNSG mice) with recombinant EBV mutants devoid of EBNA3A or EBNA3C expression. These EBV mutants established latent infection in secondary lymphoid organs of infected huNSG mice for at least 3 months, but did not cause tumor formation. Low level viral persistence in the absence of EBNA3A or EBNA3C seemed to be supported primarily by proliferation with the expression of early latent EBV gene products transitioning into absent viral protein expression without elevated lytic replication. In vitro, EBNA3A and EBNA3C deficient EBV infected B cells could be rescued from apoptosis through CD40 stimulation, mimicking T cell help in secondary lymphoid tissues. Thus, even in the absence of the oncogenes EBNA3A and 3C, EBV can access a latent gene expression pattern that is reminiscent of EBV persistence in healthy virus carriers without prior expression of its whole growth transforming program.
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Affiliation(s)
- Anita Murer
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland
| | - Donal McHugh
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland
| | - Nicole Caduff
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland
| | - Jens Kalchschmidt
- Genomics and Immunity, NIAMS, National Institutes of Health, Bethesda, MD, United States of America
| | - Mario Barros
- Institute of Pathology, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Andrea Zbinden
- Institute of Medical Virology, University of Zürich, Zürich, Switzerland
| | - Riccarda Capaul
- Institute of Medical Virology, University of Zürich, Zürich, Switzerland
| | | | - Martin Allday
- Molecular Virology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Obinna Chijioke
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland
- Institute of Pathology and Molecular Pathology, University Hospital Zürich, Zürich, Switzerland
| | - Christian Münz
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland
- * E-mail:
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9
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Zhang S, Yin J, Zhong J. Chaetocin reactivates the lytic replication of Epstein-Barr virus from latency via reactive oxygen species. SCIENCE CHINA-LIFE SCIENCES 2017; 60:66-71. [PMID: 28063010 DOI: 10.1007/s11427-016-0286-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 11/16/2016] [Indexed: 12/11/2022]
Abstract
Oxidative stress, regarded as a negative effect of free radicals in vivo, takes place when organisms suffer from harmful stimuli. Some viruses can induce the release of reactive oxygen species (ROS) in infected cells, which may be closely related with their pathogenicity. In this report, chaetocin, a fungal metabolite reported to have antimicrobial and cytostatic activity, was studied for its effect on the activation of latent Epstein-Barr virus (EBV) in B95-8 cells. We found that chaetocin remarkably up-regulated EBV lytic transcription and DNA replication at a low concentration (50 nmol L-1). The activation of latent EBV was accompanied by an increased cellular ROS level. N-acetyl-L-cysteine (NAC), an ROS inhibitor, suppressed chaetocin-induced EBV activation. Chaetocin had little effect on histone H3K9 methylation, while NAC also significantly reduced H3K9 methylation. These results suggested that chaetocin reactivates latent EBV primarily via ROS pathways.
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Affiliation(s)
- Shilun Zhang
- Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Juan Yin
- Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Jiang Zhong
- Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.
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Farina A, Farina GA. Fresh Insights into Disease Etiology and the Role of Microbial Pathogens. Curr Rheumatol Rep 2016; 18:1. [PMID: 26700911 DOI: 10.1007/s11926-015-0552-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pathogens have been implicated in the initiation and/or promotion of systemic sclerosis (scleroderma, SSc); however, no evidence was found to substantiate the direct contribution to this disease in past years. Recently, significant advances have been made in understanding the role of the innate immune system in SSc pathogenesis, supporting the idea that pathogens might interact with host innate immune-regulatory responses in SSc. In light of these findings, we review the studies that identified the presence of pathogens in SSc, along with studies on pathogens implicated in driving the innate immune dysregulation in SSc. The goal of this review is to illustrate how these pathogens, specifically viruses, may play important role both as triggers of the innate immune system, and critical players in the development of SSc disease.
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Affiliation(s)
- Antonella Farina
- Institute Pasteur-Fondazione Cenci Bolognetti, Department of Experimental Medicine, "Sapienza", University of Rome, Rome, Italy.
| | - G Alessandra Farina
- Arthritis Center, Department of Rheumatology, Boston University, 72 East Concord Street, E501, Boston, MA, 02118, USA.
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11
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Daskalogianni C, Pyndiah S, Apcher S, Mazars A, Manoury B, Ammari N, Nylander K, Voisset C, Blondel M, Fåhraeus R. Epstein-Barr virus-encoded EBNA1 and ZEBRA: targets for therapeutic strategies against EBV-carrying cancers. J Pathol 2015; 235:334-41. [PMID: 25186125 DOI: 10.1002/path.4431] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/20/2014] [Accepted: 07/24/2014] [Indexed: 12/27/2022]
Abstract
The EBV-encoded EBNA1 was first discovered 40 years ago, approximately 10 years after the presence of EBV had been demonstrated in Burkitt's lymphoma cells. It took another 10 years before the functions of EBNA1 in maintaining the viral genome were revealed, and it has since been shown to be an essential viral factor expressed in all EBV-carrying cells. Apart from serving to maintain the viral episome and to control viral replication and gene expression, EBNA1 also harbours a cis-acting mechanism that allows virus-carrying host cells to evade the immune system. This relates to a particular glycine-alanine repeat (GAr) within EBNA1 that has the capacity to suppress antigen presentation to the major histocompatibility complex (MHC) class I pathway. We discuss the role of the GAr sequence at the level of mRNA translation initiation, rather than at the protein level, as at least part of the mechanism to avoid MHC presentation. Interfering with this mechanism has become the focus of the development of immune-based therapies against EBV-carrying cancers, and some lead compounds that affect translation of GAr-carrying mRNAs have been identified. In addition, we describe the EBV-encoded ZEBRA factor and the switch from the latent to the lytic cycle as an alternative virus-specific target for treating EBV-carrying cancers. Understanding the molecular mechanisms of how EBNA1 and ZEBRA interfere with cellular pathways not only opens new therapeutic approaches but continues to reveal new cell-biological insights on the interplay between host and virus. This review is a tale of discoveries relating to how EBNA1 and ZEBRA have emerged as targets for specific cancer therapies against EBV-carrying diseases, and serves as an illustration of how mRNA translation can play roles in future immune-based strategies to target viral disease.
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12
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Abstract
Epstein-Barr virus, which mainly infects B cells and epithelial cells, has two modes of infection: latent and lytic. Epstein-Barr virus infection is predominantly latent; however, lytic infection is detected in healthy seropositive individuals and becomes more prominent in certain pathological conditions. Lytic infection is divided into several stages: early gene expression, DNA replication, late gene expression, assembly, and egress. This chapter summarizes the most recent progress made toward understanding the molecular mechanisms that regulate the different lytic stages leading to production of viral progeny. In addition, the chapter highlights the potential role of lytic infection in disease development and current attempts to purposely induce lytic infection as a therapeutic approach.
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Affiliation(s)
- Jessica McKenzie
- Department of Pediatrics, Division of Infectious Diseases, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Ayman El-Guindy
- Department of Pediatrics, Division of Infectious Diseases, Yale University School of Medicine, New Haven, CT, 06520, USA.
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13
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Abstract
Epstein-Barr virus (EBV) is widely distributed in the world and associated with a still increasing number of acute, chronic, malignant and autoimmune disease syndromes. Humoral immune responses to EBV have been studied for diagnostic, pathogenic and protective (vaccine) purposes. These studies use a range of methodologies, from cell-based immunofluorescence testing to antibody-diversity analysis using immunoblot and epitope analysis using recombinant or synthetic peptide-scanning. First, the individual EBV antigen complexes (VCA , MA, EA(D), EA(R) and EBNA) are defined at cellular and molecular levels, providing a historic overview. The characteristic antibody responses to these complexes in health and disease are described, and differences are highlighted by clinical examples. Options for EBV vaccination are briefly addressed. For a selected number of immunodominant proteins, in particular EBNA1, the interaction with human antibodies is further detailed at the epitope level, revealing interesting insights for structure, function and immunological aspects, not considered previously. Humoral immune responses against EBV-encoded tumour antigens LMP1, LMP2 and BARF1 are addressed, which provide novel options for targeted immunotherapy. Finally, some considerations on EBV-linked autoimmune diseases are given, and mechanisms of antigen mimicry are briefly discussed. Further analysis of humoral immune responses against EBV in health and disease in carefully selected patient cohorts will open new options for understanding pathogenesis of individual EBV-linked diseases and developing targeted diagnostic and therapeutic approaches.
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Farina A, Cirone M, York M, Lenna S, Padilla C, Mclaughlin S, Faggioni A, Lafyatis R, Trojanowska M, Farina GA. Epstein-Barr virus infection induces aberrant TLR activation pathway and fibroblast-myofibroblast conversion in scleroderma. J Invest Dermatol 2013; 134:954-964. [PMID: 24129067 PMCID: PMC3961515 DOI: 10.1038/jid.2013.423] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 09/16/2013] [Accepted: 09/17/2013] [Indexed: 12/28/2022]
Abstract
Scleroderma (SSc) is a complex and heterogeneous connective tissue disease mainly characterized by autoimmunity, vascular damage, and fibrosis that mostly involve the skin and lungs. Epstein–Barr virus (EBV) is a lymphotropic γ-herpesvirus that has co-evolved with human species, infecting >95% of the adult population worldwide, and has been a leading candidate in triggering several autoimmune diseases. Here we show that EBV establishes infection in the majority of fibroblasts and endothelial cells in the skin of SSc patients, characterized by the expression of the EBV noncoding small RNAs (EBERs) and the increased expression of immediate-early lytic and latency mRNAs and proteins. We report that EBV is able to persistently infect human SSc fibroblasts in vitro, inducing an aberrant innate immune response in infected cells. EBV–Toll-like receptor (TLR) aberrant activation induces the expression of selected IFN-regulatory factors (IRFs), IFN-stimulated genes (ISGs), transforming growth factor-β1 (TGFβ1), and several markers of fibroblast activation, such as smooth muscle actin and Endothelin-1, and all of these genes play a key role in determining the profibrotic phenotype in SSc fibroblasts. These findings imply that EBV infection occurring in mesenchymal, endothelial, and immune cells of SSc patients may underlie the main pathological features of SSc including autoimmunity, vasculopathy, and fibrosis, and provide a unified disease mechanism represented by EBV reactivation.
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Affiliation(s)
- Antonella Farina
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA; Institute Pasteur-Fondazione Cenci Bolognetti, Department of Experimental Medicine, University of Rome Sapienza, Rome, Italy
| | - Mara Cirone
- Institute Pasteur-Fondazione Cenci Bolognetti, Department of Experimental Medicine, University of Rome Sapienza, Rome, Italy
| | - Michael York
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Stefania Lenna
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Cristina Padilla
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Sarah Mclaughlin
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Alberto Faggioni
- Institute Pasteur-Fondazione Cenci Bolognetti, Department of Experimental Medicine, University of Rome Sapienza, Rome, Italy
| | - Robert Lafyatis
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Maria Trojanowska
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Giuseppina A Farina
- Rheumatology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
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Lan YY, Yeh TH, Lin WH, Wu SY, Lai HC, Chang FH, Takada K, Chang Y. Epstein-Barr virus Zta upregulates matrix metalloproteinases 3 and 9 that synergistically promote cell invasion in vitro. PLoS One 2013; 8:e56121. [PMID: 23409137 PMCID: PMC3567054 DOI: 10.1371/journal.pone.0056121] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 01/04/2013] [Indexed: 02/03/2023] Open
Abstract
Zta is a lytic transactivator of Epstein-Barr virus (EBV) and has been shown to promote migration and invasion of epithelial cells. Although previous studies indicate that Zta induces expression of matrix metalloproteinase (MMP) 9 and MMP1, direct evidence linking the MMPs to Zta-induced cell migration and invasion is still lacking. Here we performed a series of in vitro studies to re-examine the expression profile and biologic functions of Zta-induced MMPs in epithelial cells derived from nasopharyngeal carcinoma. We found that, in addition to MMP9, MMP3 was a new target gene upregulated by Zta. Ectopic Zta expression in EBV-negative cells increased both mRNA and protein production of MMP3. Endogenous Zta also contributed to induction of MMP3 expression, migration and invasion of EBV-infected cells. Zta activated the MMP3 promoter through three AP-1 elements, and its DNA-binding domain was required for the promoter binding and MMP3 induction. We further tested the effects of MMP3 and MMP9 on cell motility and invasiveness in vitro. Zta-promoted cell migration required MMP3 but not MMP9. On the other hand, both MMP3 and MMP9 were essential for Zta-induced cell invasion, and co-expression of the two MMPs synergistically increased cell invasiveness. Therefore, this study provides integrated evidence demonstrating that, at least in the in vitro cell models, Zta drives cell migration and invasion through MMPs.
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Affiliation(s)
- Yu-Yan Lan
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Graduate Institute of Basic Medical Sciences, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
| | - Tzu-Hao Yeh
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Department of Microbiology and Immunology, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Hung Lin
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Department of Microbiology and Immunology, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
| | - Shih-Yi Wu
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
| | - Hsiao-Ching Lai
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Graduate Institute of Basic Medical Sciences, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
| | - Fang-Hsin Chang
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Department of Microbiology and Immunology, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
| | - Kenzo Takada
- Department of Tumor Virology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Yao Chang
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Graduate Institute of Basic Medical Sciences, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
- Department of Microbiology and Immunology, Medical College and Hospital, National Cheng Kung University, Tainan, Taiwan
- * E-mail:
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16
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The effect of Epstein-Barr virus Latent Membrane Protein 2 expression on the kinetics of early B cell infection. PLoS One 2013; 8:e54010. [PMID: 23308294 PMCID: PMC3540077 DOI: 10.1371/journal.pone.0054010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 12/07/2012] [Indexed: 02/07/2023] Open
Abstract
Infection of human B cells with wild-type Epstein-Barr virus (EBV) in vitro leads to activation and proliferation that result in efficient production of lymphoblastoid cell lines (LCLs). Latent Membrane Protein 2 (LMP2) is expressed early after infection and previous research has suggested a possible role in this process. Therefore, we generated recombinant EBV with knockouts of either or both protein isoforms, LMP2A and LMP2B (Δ2A, Δ2B, Δ2A/Δ2B) to study the effect of LMP2 in early B cell infection. Infection of B cells with Δ2A and Δ2A/Δ2B viruses led to a marked decrease in activation and proliferation relative to wild-type (wt) viruses, and resulted in higher percentages of apoptotic B cells. Δ2B virus infection showed activation levels comparable to wt, but fewer numbers of proliferating B cells. Early B cell infection with wt, Δ2A and Δ2B viruses did not result in changes in latent gene expression, with the exception of elevated LMP2B transcript in Δ2A virus infection. Infection with Δ2A and Δ2B viruses did not affect viral latency, determined by changes in LMP1/Zebra expression following BCR stimulation. However, BCR stimulation of Δ2A/Δ2B cells resulted in decreased LMP1 expression, which suggests loss of stability in viral latency. Long-term outgrowth assays revealed that LMP2A, but not LMP2B, is critical for efficient long-term growth of B cells in vitro. The lowest levels of activation, proliferation, and LCL formation were observed when both isoforms were deleted. These results suggest that LMP2A appears to be critical for efficient activation, proliferation and survival of EBV-infected B cells at early times after infection, which impacts the efficient long-term growth of B cells in culture. In contrast, LMP2B did not appear to play a significant role in these processes, and long-term growth of infected B cells was not affected by the absence of this protein.
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The Epstein-Barr virus BcRF1 gene product is a TBP-like protein with an essential role in late gene expression. J Virol 2012; 86:6023-32. [PMID: 22457524 DOI: 10.1128/jvi.00159-12] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
That the expression of late genes is coupled to viral genome replication is well established for all herpesviruses, but the exact mechanisms of their regulation, especially by viral proteins, are poorly understood. Here, we report the identification of the Epstein-Barr virus (EBV) early protein BcRF1 as a viral factor crucial for the activation of late gene transcription following viral DNA replication during the productive cycle. In order to study the function of the BcRF1 protein, we constructed a recombinant EBV lacking this gene. In HEK293 cells, this recombinant virus underwent normal DNA replication during the productive cycle but failed to express high levels of late gene transcripts or proteins, resulting in a nonproductive infection. Interestingly, a TATT motif is present in the promoter of most EBV late genes, at the position of the TATA box. We show here that BcRF1 forms a complex with the TATT motif and that this interaction is required for activation of late viral gene expression. Moreover, our results suggest that BcRF1 acts via interaction with other viral proteins.
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18
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Huang Q, Gong C, Li J, Zhuo Z, Chen Y, Wang J, Hua ZC. Distance and helical phase dependence of synergistic transcription activation in cis-regulatory module. PLoS One 2012; 7:e31198. [PMID: 22299056 PMCID: PMC3267773 DOI: 10.1371/journal.pone.0031198] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 01/03/2012] [Indexed: 01/21/2023] Open
Abstract
Deciphering of the spatial and stereospecific constraints on synergistic transcription activation mediated between activators bound to cis-regulatory elements is important for understanding gene regulation and remains largely unknown. It has been commonly believed that two activators will activate transcription most effectively when they are bound on the same face of DNA double helix and within a boundary distance from the transcription initiation complex attached to the TATA box. In this work, we studied the spatial and stereospecific constraints on activation by multiple copies of bound model activators using a series of engineered relative distances and stereospecific orientations. We observed that multiple copies of the activators GAL4-VP16 and ZEBRA bound to engineered promoters activated transcription more effectively when bound on opposite faces of the DNA double helix. This phenomenon was not affected by the spatial relationship between the proximal activator and initiation complex. To explain these results, we proposed the novel concentration field model, which posits the effective concentration of bound activators, and therefore the transcription activation potential, is affected by their stereospecific positioning. These results could be used to understand synergistic transcription activation anew and to aid the development of predictive models for the identification of cis-regulatory elements.
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Affiliation(s)
- Qilai Huang
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
- The State Key Laboratory of Quality Research in Chinese Medicine and Macau Institute for Applied Research in Medicine, Macau University of Science and Technology, Macau, People's Republic of China
- Changzhou High-Tech Research Institute of Nanjing University and Jiangsu TargetPharma Laboratories Inc., Changzhou, People's Republic of China
| | - Chenguang Gong
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Jiahuang Li
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Zhu Zhuo
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Yuan Chen
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Jin Wang
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
- * E-mail: (JW); (ZH)
| | - Zi-Chun Hua
- The State Key Laboratory of Pharmaceutical Biotechnology and Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
- The State Key Laboratory of Quality Research in Chinese Medicine and Macau Institute for Applied Research in Medicine, Macau University of Science and Technology, Macau, People's Republic of China
- Changzhou High-Tech Research Institute of Nanjing University and Jiangsu TargetPharma Laboratories Inc., Changzhou, People's Republic of China
- * E-mail: (JW); (ZH)
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Epithelial cell retention of transcriptionally active, P3HR-1-derived heterogeneous Epstein-Barr virus DNA with concurrent loss of parental virus. J Virol 2011; 85:7634-43. [PMID: 21593154 DOI: 10.1128/jvi.00045-11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deleted, rearranged, heterogeneous (het) Epstein-Barr virus (EBV) DNA with the distinctive capability of disrupting EBV latency has been reported in biopsy samples of EBV-associated tumors whose onset in immunocompetent hosts is characteristically preceded by an antibody response indicative of EBV reactivation. Using the EBV P3HR-1 strain, we have reproduced in long-term culture of SVK epithelial cells an unusual pattern of infection previously observed in a subset of tumor biopsy samples: the persistence of het DNA in the absence of the parental helper virus. Fluorescence in situ hybridization (FISH) of infected cell subclones indicated the retention of het DNA in an integrated form. Incorporation of an intact het DNA molecule was confirmed by PCR, using primers that framed junctions of the four rearranged EBV DNA segments comprising P3HR-1-derived het DNA. Structural analysis of EBV terminal repeats revealed a banding pattern consistent with the integration of het DNA as a concatemer. Linkage of concatemeric monomers was defined at a nucleotide level, and that junctional sequence was detected in cell-free P3HR-1 virion DNA, confirming that subgenomic het DNA was packaged into infectious particles in a concatemeric configuration. Stable integration into cells having lost the standard viral genome allowed the unambiguous designation of het DNA as the source for viral gene products potentially encoded by both. Continuous expression of the latency-to-lytic switch protein Zta and detection of the BALF4 gene product gB, known to expand the target cell range of standard virus when incorporated at augmented levels into infectious progeny, add to a presumption of het DNA-enhanced pathogenesis in diseases of EBV reactivation.
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Jia Y, Wang Y, Chao Y, Jing Y, Sun Z, Luo B. Sequence analysis of the Epstein-Barr virus (EBV) BRLF1 gene in nasopharyngeal and gastric carcinomas. Virol J 2010; 7:341. [PMID: 21106109 PMCID: PMC3002924 DOI: 10.1186/1743-422x-7-341] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 11/25/2010] [Indexed: 12/15/2022] Open
Abstract
Background Epstein-Barr virus (EBV) has a biphasic infection cycle consisting of a latent and a lytic replicative phase. The product of immediate-early gene BRLF1, Rta, is able to disrupt the latency phase in epithelial cells and certain B-cell lines. The protein Rta is a frequent target of the EBV-induced cytotoxic T cell response. In spite of our good understanding of this protein, little is known for the gene polymorphism of BRLF1. Results BRLF1 gene was successfully amplified in 34 EBV-associated gastric carcinomas (EBVaGCs), 57 nasopharyngeal carcinomas (NPCs) and 28 throat washings (TWs) samples from healthy donors followed by PCR-direct sequencing. Fourteen loci were found to be affected by amino acid changes, 17 loci by silent nucleotide changes. According to the phylogenetic tree, 5 distinct subtypes of BRLF1 were identified, and 2 subtypes BR1-A and BR1-C were detected in 42.9% (51/119), 42.0% (50/119) of samples, respectively. The distribution of these 2 subtypes among 3 types of specimens was significantly different. The subtype BR1-A preferentially existed in healthy donors, while BR1-C was seen more in biopsies of NPC. A silent mutation A/G was detected in all the isolates. Among 3 functional domains, the dimerization domain of Rta showed a stably conserved sequence, while DNA binding and transactivation domains were detected to have multiple mutations. Three of 16 CTL epitopes, NAA, QKE and ERP, were affected by amino acid changes. Epitope ERP was relatively conserved; epitopes NAA and QKE harbored more mutations. Conclusions This first detailed investigation of sequence variations in BRLF1 gene has identified 5 distinct subtypes. Two subtypes BR1-A and BR1-C are the dominant genotypes of BRLF1. The subtype BR1-C is more frequent in NPCs, while BR1-A preferentially presents in healthy donors. BR1-C may be associated with the tumorigenesis of NPC.
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Affiliation(s)
- Yuping Jia
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao, PR China
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The nuclear and adherent junction complex component protein ubinuclein negatively regulates the productive cycle of Epstein-Barr virus in epithelial cells. J Virol 2010; 85:784-94. [PMID: 21084479 DOI: 10.1128/jvi.01397-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Epstein-Barr Virus (EBV) productive cycle is initiated by the expression of the viral trans-activator EB1 (also called Zebra, Zta, or BZLF1), which belongs to the basic leucine zipper transcription factor family. We have previously identified the cellular NACos (nuclear and adherent junction complex components) protein ubinuclein (Ubn-1) as a partner for EB1, but the function of this complex has never been studied. Here, we have evaluated the consequences of this interaction on the EBV productive cycle and find that Ubn-1 overexpression represses the EBV productive cycle whereas Ubn-1 downregulation by short hairpin RNA (shRNA) increases virus production. By a chromatin immunoprecipitation (ChIP) assay, we show that Ubn-1 blocks EB1-DNA interaction. We also show that in epithelial cells, relocalization and sequestration of Ubn-1 to the tight junctions of nondividing cells allow increased activation of the productive cycle. We propose a model in which Ubn-1 is a modulator of the EBV productive cycle: in proliferating epithelial cells, Ubn-1 is nuclear and inhibits activation of the productive cycle, whereas in differentiated cells, Ubn-1 is sequestrated to tight junctions, thereby allowing EB1 to fully function in the nucleus.
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Detection of EBV, HBV, HCV, HIV-1, HTLV-I and -II, and SMRV in human and other primate cell lines. J Biomed Biotechnol 2010; 2010:904767. [PMID: 20454443 PMCID: PMC2861168 DOI: 10.1155/2010/904767] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/21/2010] [Accepted: 02/10/2010] [Indexed: 12/31/2022] Open
Abstract
The high prevalence of contaminated cell cultures suggests that viral contaminations might be distributed among cultures. We investigated more than 460 primate cell lines for Epstein-Barr (EBV), hepatitis B (HBV), hepatitis C (HCV), human immunodeficiency virus type 1 (HIV-1), human T-cell leukemia/lymphoma virus I and II (HTLV-I/-II), and squirrel monkey retrovirus (SMRV) infections for risk assessment. None of the cell lines were infected with HCV, HIV-1, or HTLV-I/-II. However, one cell line displayed reverse transcriptase activity. Thirty-nine cell lines harbored EBV DNA sequences. Studies on the lytic phase of EBV revealed that five cell lines produce EBV particles and six further cell lines produced EBV upon stimulation. One cell line contained an integrated HBV genome fragment but showed no virus production. Six cell lines were SMRV-infected. Newly established cell lines should be tested for EBV infections to detect B-lymphoblastoid cell lines (B-LCL). B-LCLs established with EBV from cell line B95-8 should be tested for SMRV infections.
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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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24
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Epstein-Barr virus lytic transactivator Zta enhances chemotactic activity through induction of interleukin-8 in nasopharyngeal carcinoma cells. J Virol 2008; 82:3679-88. [PMID: 18234802 DOI: 10.1128/jvi.02301-07] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV)-associated, undifferentiated type of nasopharyngeal carcinoma (NPC) is characterized by intensive leukocyte infiltration. Interaction between the infiltrating cells and the tumor cells has been considered crucial for NPC development. Recruitment of the infiltrates can be directed by certain chemokines present in the NPC tissues. It is unknown whether and how EBV lytic infection regulates expression of the chemokines. Using an antibody array, we first found that several chemokines secreted from EBV-infected NPC cells are increased upon EBV reactivation into the lytic cycle, and interleukin-8 (IL-8) is the chemokine upregulated most significantly and consistently. Further studies showed that the EBV lytic transactivator Zta is a potent inducer of IL-8 in NPC cells, augmenting secreted and intracellular IL-8 proteins, as well as IL-8 RNA. Zta upregulates Egr-1, a cellular transcription factor that has been involved in upregulation of IL-8, but the Zta-induced IL-8 expression is independent of Egr-1. The ability of Zta to transactivate the IL-8 promoter is important for the induction of IL-8, and we have identified two Zta-responsive elements in the promoter. Zta can bind to these two elements in vitro and can also be recruited to the IL-8 promoter in vivo. DNA-binding-defective Zta mutants can neither activate the IL-8 promoter nor induce IL-8 production. In addition, Zta-expressing NPC cells exert enhanced chemotactic activity that is mainly mediated by IL-8. Since IL-8 may contribute to not only leukocyte infiltration but also multiple oncogenic processes, the present study provides a potential link between EBV lytic infection and pathogenesis of NPC.
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Bhende PM, Dickerson SJ, Sun X, Feng WH, Kenney SC. X-box-binding protein 1 activates lytic Epstein-Barr virus gene expression in combination with protein kinase D. J Virol 2007; 81:7363-70. [PMID: 17494074 PMCID: PMC1933364 DOI: 10.1128/jvi.00154-07] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Epstein-Barr virus (EBV) establishes a latent form of infection in memory B cells, while antibody-secreting plasma cells often harbor the lytic form of infection. The switch between latent and lytic EBV infection is mediated by the two viral immediate-early proteins BZLF1 (Z) and BRLF1 (R), which are not expressed in latently infected B cells. Here we demonstrate that a cellular transcription factor that plays an essential role in plasma cell differentiation, X-box-binding protein 1 (XBP-1), also activates the transcription of the two EBV immediate-early gene promoters. In reporter gene assays, XBP-1 alone was sufficient to activate the R promoter, whereas the combination of XBP-1 and protein kinase D (PKD) was required for efficient activation of the Z promoter. Most importantly, the expression of XBP-1 and activated PKD was sufficient to induce lytic viral gene expression in EBV-positive nasopharyngeal carcinoma cells and lymphoblastoid cells, while an XBP-1 small interfering RNA inhibited constitutive lytic EBV gene expression in lymphoblastoid cells. These results suggest that the plasma cell differentiation factor XBP-1, in combination with activated PKD, can mediate the reactivation of EBV, thereby allowing the viral life cycle to be intimately linked to plasma cell differentiation.
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Affiliation(s)
- Prasanna M Bhende
- Department of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Miller G, El-Guindy A, Countryman J, Ye J, Gradoville L. Lytic Cycle Switches of Oncogenic Human Gammaherpesviruses1. Adv Cancer Res 2007; 97:81-109. [PMID: 17419942 DOI: 10.1016/s0065-230x(06)97004-3] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The seminal experiments of George and Eva Klein helped to define the two life cycles of Epstein-Barr Virus (EBV), namely latency and lytic or productive infection. Their laboratories described latent nuclear antigens expressed during latency and discovered several chemicals that activated the viral lytic cycle. The mechanism of the switch between latency and the lytic cycle of EBV and Kaposi's sarcoma-associated herpesvirus (KSHV) can be studied in cultured B cell lines. Lytic cycle activation of EBV is controlled by two viral transcription factors, ZEBRA and Rta. The homologue of Rta encoded in ORF50 is the lytic cycle activator of KSHV. Control of the lytic cycle can be divided into two distinct phases. Upstream events control expression of the virally encoded lytic cycle activator genes. Downstream events represent tasks carried out by the viral proteins in driving expression of lytic cycle genes and lytic viral DNA replication. In this chapter, we report three recent groups of experiments relating to upstream and downstream events. Azacytidine (AzaC) is a DNA methyltransferase inhibitor whose lytic cycle activation capacity was discovered by G. Klein and coworkers. We find that AzaC rapidly activates the EBV lytic cycle but does not detectably alter DNA methylation or histone acetylation on the promoters of the EBV lytic cycle activator genes. AzaC probably acts via a novel, yet to be elucidated, mechanism. The lytic cycle of both EBV and KSHV can be activated by sodium butyrate (NaB), a histone deacetylase inhibitor whose activity in disrupting latency was also discovered by G. Klein and coworkers. Activation of EBV by NaB requires protein synthesis; activation of KSHV is independent of protein synthesis. Thus, NaB works by a different pathway on the two closely related viruses. ZEBRA, the major downstream mediator of EBV lytic cycle activation is both a transcription activator and an essential replication protein. We show that phosphorylation of ZEBRA at its casein kinase 2 (CK2) site separates these two functions. Phosphorylation by CK2 is required for ZEBRA to activate lytic replication but not to induce expression of early lytic cycle genes. We discuss a number of unsolved mysteries about lytic cycle activation which should provide fertile territory for future research.
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MESH Headings
- Azacitidine/pharmacology
- Cycloheximide/pharmacology
- Cytopathogenic Effect, Viral/drug effects
- Cytopathogenic Effect, Viral/genetics
- Cytopathogenic Effect, Viral/physiology
- DNA Replication
- DNA, Viral/biosynthesis
- DNA, Viral/genetics
- Epstein-Barr Virus Infections/virology
- Gene Expression Regulation, Viral/drug effects
- Gene Expression Regulation, Viral/genetics
- Herpesviridae Infections/virology
- Herpesvirus 4, Human/drug effects
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/physiology
- Herpesvirus 8, Human/drug effects
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/physiology
- Humans
- Immediate-Early Proteins/physiology
- Mutation
- Oncogenic Viruses/physiology
- Phosphorylation
- Protein Processing, Post-Translational
- Protein Structure, Tertiary
- Trans-Activators/chemistry
- Trans-Activators/genetics
- Trans-Activators/physiology
- Tumor Virus Infections/virology
- Virus Latency/drug effects
- Virus Latency/genetics
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Affiliation(s)
- George Miller
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Heston L, El-Guindy A, Countryman J, Dela Cruz C, Delecluse HJ, Miller G. Amino acids in the basic domain of Epstein-Barr virus ZEBRA protein play distinct roles in DNA binding, activation of early lytic gene expression, and promotion of viral DNA replication. J Virol 2006; 80:9115-33. [PMID: 16940523 PMCID: PMC1563939 DOI: 10.1128/jvi.00909-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The ZEBRA protein of Epstein-Barr virus (EBV) drives the viral lytic cycle cascade. The capacity of ZEBRA to recognize specific DNA sequences resides in amino acids 178 to 194, a region in which 9 of 17 residues are either lysine or arginine. To define the basic domain residues essential for activity, a series of 46 single-amino-acid-substitution mutants were examined for their ability to bind ZIIIB DNA, a high-affinity ZEBRA binding site, and for their capacity to activate early and late EBV lytic cycle gene expression. DNA binding was obligatory for the protein to activate the lytic cascade. Nineteen mutants that failed to bind DNA were unable to disrupt latency. A single acidic replacement of a basic amino acid destroyed DNA binding and the biologic activity of the protein. Four mutants that bound weakly to DNA were defective at stimulating the expression of Rta, the essential first target of ZEBRA in lytic cycle activation. Four amino acids, R183, A185, C189, and R190, are likely to contact ZIIIB DNA specifically, since alanine or valine substitutions at these positions drastically weakened or eliminated DNA binding. Twenty-three mutants were proficient in binding to ZIIIB DNA. Some DNA binding-proficient mutants were refractory to supershift by BZ-1 monoclonal antibody (epitope amino acids 214 to 230), likely as the result of the increased solubility of the mutants. Mutants competent to bind DNA could be separated into four functional groups: the wild-type group (eight mutants), a group defective at activating Rta (five mutants, all with mutations at the S186 site), a group defective at activating EA-D (three mutants with the R179A, S186T, and K192A mutations), and a group specifically defective at activating late gene expression (seven mutants). Three late mutants, with a Y180A, Y180E, or K188A mutation, were defective at stimulating EBV DNA replication. This catalogue of point mutants reveals that basic domain amino acids play distinct functions in binding to DNA, in activating Rta, in stimulating early lytic gene expression, and in promoting viral DNA replication and viral late gene expression. These results are discussed in relationship to the recently solved crystal structure of ZEBRA bound to an AP-1 site.
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Affiliation(s)
- Lee Heston
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520, USA
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Batisse J, Manet E, Middeldorp J, Sergeant A, Gruffat H. Epstein-Barr virus mRNA export factor EB2 is essential for intranuclear capsid assembly and production of gp350. J Virol 2006; 79:14102-11. [PMID: 16254345 PMCID: PMC1280191 DOI: 10.1128/jvi.79.22.14102-14111.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Most human herpesviruses, including Epstein-Barr virus (EBV), express a protein which functions primarily as an mRNA export factor. Previously, we deleted the gene for the Epstein-Barr virus mRNA export factor EB2 from the EBV genome and then introduced the mutated genome into 293 cells. Using a transcomplementation assay in which ectopic expression of the transcription factor EB1/ZEBRA was sufficient to induce the EBV productive cycle, we showed that Ori-Lyt-dependent replication of the EBV DNA occurs in the absence of EB2, indicating that EB2 is not essential for the expression and export of early mRNAs. However, in the absence of EB2, no infectious viral particles are produced (H. Gruffat, J. Batisse, D. Pich, B. Neuhierl, E. Manet, W. Hammerschmidt, and A. Sergeant, J. Virol. 76:9635-9644, 2002). In this report, we now show that EB2 is essential for the nuclear export of most, but not all, late mRNAs produced from intronless genes that translate into proteins involved in intranuclear capsid assembly and maturation. As a consequence, we show that EB2 is essential for the proper assembly of intranuclear capsids. Interestingly, the late BLLF1 gene contains an intron, and both unspliced and spliced mRNAs must be exported to the cytoplasm to be translated into gp350 and gp220, respectively (M. Hummel, D. A. Thorley-Lawson, and E. Kieff, J. Virol. 49:413-417, 1984). Our results also demonstrate that although BLLF1 spliced mRNAs are exported to the cytoplasm independently of EB2, EB2 is essential for the nuclear export of unspliced BLLF1 mRNA. In the same assay, herpes simplex virus 1 ICP27 completely inhibited the nuclear export of BLLF1 spliced mRNAs whereas unspliced BLLF1 mRNAs were exported, confirming that in a physiological assay, ICP27 inhibits splicing.
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Affiliation(s)
- Julien Batisse
- U412 INSERM, ENS-Lyon, IFR 128 BioSciences Lyon-Gerland, 46 allée d'Italie, F-69364 Lyon cedex 07, France
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29
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Hsu TY, Chang Y, Wang PW, Liu MY, Chen MR, Chen JY, Tsai CH. Reactivation of Epstein–Barr virus can be triggered by an Rta protein mutated at the nuclear localization signal. J Gen Virol 2005; 86:317-322. [PMID: 15659750 DOI: 10.1099/vir.0.80556-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rta, an immediate-early protein of Epstein–Barr virus (EBV), is a transcriptional activator that induces lytic gene expression and triggers virus reactivation. Being located predominantly in the nucleus, Rta can exert its transactivation function through either direct DNA binding or certain indirect mechanisms mediated by cellular signalling and other transcriptional factors. This study examined whether the subcellular localization of Rta was critical for the induction of target genes. First, 410KRKK413 was identified as a nuclear localization signal (NLS) of Rta. An Rta mutant with the NLS converted to 410AAAA413 showed cytoplasmic localization and failed to activate the promoter of BGLF5. Interestingly, ectopic expression of the Rta mutant still disrupted EBV latency in an epithelial cell line. Reporter gene assays revealed that the NLS-mutated Rta retained the ability to activate two lytic promoters, Zp and Rp, at a considerable level. Thus, the cytoplasmic Rta mutant could induce expression of endogenous Zta and Rta, triggering reactivation of EBV.
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Affiliation(s)
- Tsuey-Ying Hsu
- Department of Microbiology, College of Medicine, National Taiwan University, Room 722, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Yao Chang
- Department of Microbiology, College of Medicine, National Taiwan University, Room 722, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Pei-Wen Wang
- Department of Microbiology, College of Medicine, National Taiwan University, Room 722, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Mei-Ying Liu
- Center of General Education, National Taipei College of Nursing, Taipei, Taiwan
| | - Mei-Ru Chen
- Department of Microbiology, College of Medicine, National Taiwan University, Room 722, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Jen-Yang Chen
- Extramural Research Affairs Department, National Health Research Institute, Taipei, Taiwan
- Department of Microbiology, College of Medicine, National Taiwan University, Room 722, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Ching-Hwa Tsai
- Department of Microbiology, College of Medicine, National Taiwan University, Room 722, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
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Laichalk LL, Thorley-Lawson DA. Terminal differentiation into plasma cells initiates the replicative cycle of Epstein-Barr virus in vivo. J Virol 2005; 79:1296-307. [PMID: 15613356 PMCID: PMC538585 DOI: 10.1128/jvi.79.2.1296-1307.2005] [Citation(s) in RCA: 363] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In this paper we demonstrate that the cells which initiate replication of Epstein-Barr virus (EBV) in the tonsils of healthy carriers are plasma cells (CD38hi, CD10-, CD19+, CD20lo, surface immunoglobulin negative, and cytoplasmic immunoglobulin positive). We further conclude that differentiation into plasma cells, and not the signals that induce differentiation, initiates viral replication. This was confirmed by in vitro studies showing that the promoter for BZLF1, the gene that begins viral replication, becomes active only after memory cells differentiate into plasma cells and is also active in plasma cell lines. This differs from the reactivation of BZLF1 in vitro, which occurs acutely and is associated with apoptosis and not with differentiation. We suggest that differentiation and acute stress represent two distinct pathways of EBV reactivation in vivo. The fraction of cells replicating the virus decreases as the cells progress through the lytic cycle such that only a tiny fraction actually release infectious virus. This may reflect abortive replication or elimination of cells by the cellular immune response. Consistent with the later conclusion, the cells did not down regulate major histocompatibility complex class I molecules, suggesting that this is not an immune evasion tactic used by EBV and that the cells remain vulnerable to cytotoxic-T-lymphocyte attack.
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Affiliation(s)
- Lauri L Laichalk
- Dept. of Pathology, Jaharis Building, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
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31
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Johannsen E, Luftig M, Chase MR, Weicksel S, Cahir-McFarland E, Illanes D, Sarracino D, Kieff E. Proteins of purified Epstein-Barr virus. Proc Natl Acad Sci U S A 2004; 101:16286-91. [PMID: 15534216 PMCID: PMC528973 DOI: 10.1073/pnas.0407320101] [Citation(s) in RCA: 333] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mature Epstein-Barr virus (EBV) was purified from the culture medium of infected lymphocytes made functionally conditional for Zta activation of lytic replication by an in-frame fusion with a mutant estrogen receptor. Proteins in purified virus preparations were separated by gradient gel electrophoresis and trypsin-digested; peptides were then analyzed by tandem hydrophobic chromatography, tandem MS sequencing, and MS scans. Potential peptides were matched with EBV and human gene ORFs. Mature EBV was mostly composed of homologues of proteins previously found in a herpes virion. However, EBV homologues to herpes simplex virus capsid-associated or tegument components UL7 (BBRF2), UL14 (BGLF3), and EBV BFRF1 were not significantly detected. Instead, probable tegument components included the EBV and gamma-herpesvirus-encoded BLRF2, BRRF2, BDLF2 and BKRF4 proteins. Actin was also a major tegument protein, and cofilin, tubulin, heat shock protein 90, and heat shock protein 70 were substantial components. EBV envelope glycoprotein gp350 was highly abundant, followed by glycoprotein gH, intact and furin-cleaved gB, gM, gp42, gL, gp78, gp150, and gN. BILF1 (gp64) and proteins associated with latent EBV infection were not detected in virions.
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Affiliation(s)
- Eric Johannsen
- Program in Virology, Department of Microbiology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA
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32
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Bowie AG, Zhan J, Marshall WL. Viral appropriation of apoptotic and NF-kappaB signaling pathways. J Cell Biochem 2004; 91:1099-108. [PMID: 15048867 DOI: 10.1002/jcb.20026] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Viruses utilize a variety of strategies to evade the host immune response and replicate in the cells they infect. The comparatively large genomes of the Orthopoxviruses and gammaherpesviruses encode several immunomodulatory proteins that are homologous to component of the innate immune system of host cells, which are reviewed here. However, the viral mechanisms used to survive host responses are quite distinct between these two virus families. Poxviruses undergo continuous lytic replication in the host cytoplasm while expressing many genes that inhibit innate immune responses. In contrast, herpesviruses persist in a latent state during much of their lifecycle while expressing only a limited number of relatively non-immunogenic viral proteins, thereby avoiding the adaptive immune response. Poxviruses suppress, whereas latent gammaherpesviruses activate, signaling by NF-kappaB, yet both viruses target similar host signaling pathways to suppress the apoptotic response. Here, modulation of apoptotic and NF-kappaB signal transduction pathways are examined as examples of common pathways appropriated in contrasting ways by herpesviruses and poxviruses.
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Affiliation(s)
- Andrew G Bowie
- Viral Immune Evasion Group, Department of Biochemistry, Trinity College, Dublin 2, Ireland
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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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Chang Y, Chang SS, Lee HH, Doong SL, Takada K, Tsai CH. Inhibition of the Epstein–Barr virus lytic cycle by Zta-targeted RNA interference. J Gen Virol 2004; 85:1371-1379. [PMID: 15166418 DOI: 10.1099/vir.0.79886-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Epstein–Barr virus (EBV) reactivation into the lytic cycle plays certain roles in the development of EBV-associated diseases, so an effective strategy to block the viral lytic cycle may be of value to reduce the disease risk or to improve the clinical outcome. This study examined whether the EBV lytic cycle could be inhibited using RNA interference (RNAi) directed against the essential viral gene Zta. In cases of EBV reactivation triggered by chemicals or by exogenous Rta, Zta-targeted RNAi prevented the induction of Zta and its downstream genes and further blocked the lytic replication of viral genomes. This antiviral effect of RNAi was not likely to be mediated by activation of the interferon pathway, as phosphorylation of STAT1 was not induced. In addition, novel EBV-infected epithelial cells showing constitutive activation of the lytic cycle were cloned; such established lytic infection was also suppressed by Zta-targeted RNAi. These results indicate that RNAi can be used to inhibit the EBV lytic cycle effectively in vitro and could also be of potential use to develop anti-EBV treatments.
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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 Road, Taipei, Taiwan
| | - Shih-Shin Chang
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Room 714, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Heng-Huan Lee
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Room 714, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Shin-Lian Doong
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Room 714, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
| | - Kenzo Takada
- Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Ching-Hwa Tsai
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Room 714, Number 1, Section 1, Jen-Ai Road, Taipei, Taiwan
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Hochberg D, Souza T, Catalina M, Sullivan JL, Luzuriaga K, Thorley-Lawson DA. Acute infection with Epstein-Barr virus targets and overwhelms the peripheral memory B-cell compartment with resting, latently infected cells. J Virol 2004; 78:5194-204. [PMID: 15113901 PMCID: PMC400374 DOI: 10.1128/jvi.78.10.5194-5204.2004] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In this paper we demonstrate that during acute infection with Epstein-Barr virus (EBV), the peripheral blood fills up with latently infected, resting memory B cells to the point where up to 50% of all the memory cells may carry EBV. Despite this massive invasion of the memory compartment, the virus remains tightly restricted to memory cells, such that, in one donor, fewer than 1 in 10(4) infected cells were found in the naive compartment. We conclude that, even during acute infection, EBV persistence is tightly regulated. This result confirms the prediction that during the early phase of infection, before cellular immunity is effective, there is nothing to prevent amplification of the viral cycle of infection, differentiation, and reactivation, causing the peripheral memory compartment to fill up with latently infected cells. Subsequently, there is a rapid decline in infected cells for the first few weeks that approximates the decay in the cytotoxic-T-cell responses to viral replicative antigens. This phase is followed by a slower decline that, even by 1 year, had not reached a steady state. Therefore, EBV may approach but never reach a stable equilibrium.
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Affiliation(s)
- Donna Hochberg
- Department of Pathology, Jaharis Building, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA
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36
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Rivailler P, Cho YG, Wang F. Complete genomic sequence of an Epstein-Barr virus-related herpesvirus naturally infecting a new world primate: a defining point in the evolution of oncogenic lymphocryptoviruses. J Virol 2002; 76:12055-68. [PMID: 12414947 PMCID: PMC136909 DOI: 10.1128/jvi.76.23.12055-12068.2002] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Callitrichine herpesvirus 3 (CalHV-3) was isolated from a B-cell lymphoma arising spontaneously in the New World primate Callithrix jacchus, the common marmoset. Partial genomic sequence analysis definitively identified CalHV-3 as a member of the Epstein-Barr virus (EBV)-related lymphocryptovirus (LCV) genus and extended the known host range of LCVs beyond humans and Old World nonhuman primates. We have now completed the first genomic sequence of an LCV infecting a New World primate by describing the unique short region, the major internal repeat, and a portion of the unique long region. This portion of the genome contains the putative latent origin of replication and 13 additional open reading frames (ORFs), 5 of which show no homology to any viral or cell genes. One of the novel genes, C5, is a positional homologue for the transformation-essential EBV gene EBNA-2. The marmoset LCV genome is also notable for the absence of viral interleukin-10 and small nonpolyadenylated RNA homologues. Marmoset LCV transcripts encoding putative latent infection nuclear proteins have a common leader sequence that is spliced from the major internal repeat in a manner similar to that of the EBV EBNA-LP, suggesting strong conservation of a common promoter and splicing of these latent infection mRNAs. An EBV LMP2A-like spliced transcript crossing the terminal repeats encodes a unique ORF, C7, with multiple transmembrane domains and tyrosine kinase phosphorylation sites functionally reminiscent of EBV LMP2A. However, the carboxy-terminal location of the candidate phosphotyrosine residues is more reminiscent of the Kaposi's sarcoma-associated herpesvirus K15 gene and provides potential evidence of an evolutionary transition from rhadinoviruses to lymphocryptoviruses. The unusual gene repertoire of the marmoset LCV differentiates ancestral viral genes likely present in an LCV progenitor from viral genes acquired later as primates and LCV coevolved, providing a defining point in the evolution of oncogenic LCVs.
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Affiliation(s)
- Pierre Rivailler
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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Arcenas RC, Widen R. Epstein-Barr virus reactivation after superinfection of the BJAB-B1 and P3HR-1 cell lines with cytomegalovirus. BMC Microbiol 2002; 2:20. [PMID: 12137568 PMCID: PMC119847 DOI: 10.1186/1471-2180-2-20] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2002] [Accepted: 07/23/2002] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Studies examining herpesvirus-herpesvirus (cytomegalovirus (CMV)-Epstein-Barr virus (EBV)) interactions are limited, and many of the studies have been clinical observations suggesting such an interaction exists. This report aims to examine the in vitro susceptibilities of BJAB-B1 and P3HR-1 cells (EBV positive Burkitt's lymphoma B-cell lines) to a CMV superinfection; and show that EBV reactivation occurs after CMV superinfects these cell lines. RESULTS The BJAB-B1 and P3HR-1 cells were observed to be susceptible to a CMV superinfection by detecting the major immediate early (MIE) viral transcript and protein (p52) expression. The BZLF1 transcript was observed in both cell lines superinfected with CMV, indicating EBV reactivation. BZLF1 protein was observed in the BJAB-B1 cells. Antigen detection was not performed in the P3HR-1 cells. CONCLUSION The results from the in vitro superinfections support the in vivo studies suggesting a CMV infection is related to an EBV reactivation and suggests that CMV may be important as a co-factor in EBV pathogenesis in the immunocompromised patient.
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MESH Headings
- Antigens, Viral/biosynthesis
- Burkitt Lymphoma/pathology
- Burkitt Lymphoma/virology
- Cytomegalovirus/pathogenicity
- Cytomegalovirus Infections/virology
- Gene Expression Regulation, Viral/genetics
- Genes, Immediate-Early/genetics
- Genes, Viral/genetics
- Glyceraldehyde-3-Phosphate Dehydrogenases/biosynthesis
- Glyceraldehyde-3-Phosphate Dehydrogenases/physiology
- Herpesvirus 4, Human/growth & development
- Herpesvirus 4, Human/metabolism
- Humans
- Immediate-Early Proteins/biosynthesis
- Lymphoma, B-Cell/pathology
- Lymphoma, B-Cell/virology
- RNA Stability/physiology
- RNA, Viral/physiology
- Superinfection/virology
- Tumor Cells, Cultured
- Tumor Virus Infections/virology
- Viral Envelope Proteins/biosynthesis
- Viral Matrix Proteins/biosynthesis
- Viral Structural Proteins/genetics
- Virus Activation/genetics
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Affiliation(s)
- Rodney C Arcenas
- Department of Medical Microbiology and Immunology, College of Medicine, University of South Florida, Tampa, Fl 33612
- Esoteric Testing and Research Department, Clinical Laboratory, Tampa General Hospital, Davis Islands, Fl 33606
| | - Raymond Widen
- Department of Medical Microbiology and Immunology, College of Medicine, University of South Florida, Tampa, Fl 33612
- Esoteric Testing and Research Department, Clinical Laboratory, Tampa General Hospital, Davis Islands, Fl 33606
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38
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Liang CL, Chen JL, Hsu YPP, Ou JT, Chang YS. Epstein-Barr virus BZLF1 gene is activated by transforming growth factor-beta through cooperativity of Smads and c-Jun/c-Fos proteins. J Biol Chem 2002; 277:23345-57. [PMID: 11971895 DOI: 10.1074/jbc.m107420200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Induction of Epstein-Barr virus (EBV) production in an EBV-positive cell is achieved by expression of the gene BZLF1 that switches the latent state into a lytic state. The expression of the BZLF1 gene is initiated from the promoter Zp, which is normally suppressed in EBV-transformed B cells. The BZLF1 gene can be induced for expression by activating agents, such as transforming growth factor-beta (TGF-beta) and 12-O-tetradecanoylphorbol-13-acetate. The 12-O-tetradecanoylphorbol-13-acetate-responsive element located in the Zp is the AP-1 motif. The TGF-beta-responsive element, however, has not been determined. We demonstrated that the Smad4-binding element site, GTCTG, from -233 to -229, was located in the regulatory region of the Zp relative to the BZLF1 transcription initiation site and was physically associated with Smad4. This association was important for the TGF-beta induction of Zp. We also showed from the results of co-transfection experiments and electrophoretic mobility shift assays that both the AP-1 motif and Smad4-binding element site appeared to be required for the TGF-beta-induced activation of Zp. This effect was mediated through the cooperation of Smad3/Smad4 and c-Jun/c-Fos that formed a complex. TGF-beta treatment of Rael cells induced production of infectious EBV particles that was capable of infecting EBV-negative CA46 cells and transforming normal cord blood B cells, in vitro. Those data support a mechanism that TGF-beta induces the latent EBV in cells to enter the viral lytic cycle through regulation of key viral proteins by TGF-beta signal transducers. Those findings also suggest a role of TGF-beta in EBV-associated diseases.
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Affiliation(s)
- Chih-Lung Liang
- Institute of Microbiology and Immunology, National Yang-Ming University, Shih-Pai 112, Taipei, Republic of China
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39
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Bornkamm GW, Hammerschmidt W. Molecular virology of Epstein-Barr virus. Philos Trans R Soc Lond B Biol Sci 2001; 356:437-59. [PMID: 11313004 PMCID: PMC1088437 DOI: 10.1098/rstb.2000.0781] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Epstein-Barr virus (EBV) interacts with its host in three distinct ways in a highly regulated fashion: (i) EBV infects human B lymphocytes and induces proliferation of the infected cells, (ii) it enters into a latent phase in vivo that follows the proliferative phase, and (iii) it can be reactivated giving rise to the production of infectious progeny for reinfection of cells of the same type or transmission of the virus to another individual. In healthy people, these processes take place simultaneously in different anatomical and functional compartments and are linked to each other in a highly dynamic steady-state equilibrium. The development of a genetic system has paved the way for the dissection of those processes at a molecular level that can be studied in vitro, i.e. B-cell immortalization and the lytic cycle leading to production of infectious progeny. Polymerase chain reaction analyses coupled to fluorescent-activated cell sorting has on the other hand allowed a descriptive analysis of the virus-host interaction in peripheral blood cells as well as in tonsillar B cells in vivo. This paper is aimed at compiling our present knowledge on the process of B-cell immortalization in vitro as well as in vivo latency, and attempts to integrate this knowledge into the framework of the viral life cycle in vivo.
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Affiliation(s)
- G W Bornkamm
- Institut für Klinische Molekularbiologie und Tumorgenetik, Abteilung für Genvektoren, GSF-Forschungszentrum für Umwelt und Gesundheit, Marchioninistrasse 25, D-83177 München, Germany.
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40
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Goodwin DJ, Walters MS, Smith PG, Thurau M, Fickenscher H, Whitehouse A. Herpesvirus saimiri open reading frame 50 (Rta) protein reactivates the lytic replication cycle in a persistently infected A549 cell line. J Virol 2001; 75:4008-13. [PMID: 11264393 PMCID: PMC114895 DOI: 10.1128/jvi.75.8.4008-4013.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Herpesviruses occur in two distinct forms of infection, lytic replication and latent persistence. In this study, we investigated the molecular mechanisms that govern the latent-lytic switch in the prototype gamma-2 herpesvirus, herpesvirus saimiri (HVS). We utilized a persistently HVS-infected A549 cell line, in which HVS DNA is stably maintained as nonintegrated circular episomes, to assess the role of the open reading frame 50 (ORF 50) (Rta) proteins in the latent-lytic switch. Northern blot analysis and virus recovery assays determined that the ORF 50a gene product, when expressed under the control of a constitutively active promoter, was sufficient to reactivate the entire lytic replication cycle, producing infectious virus particles. Furthermore, although the ORF 50 proteins of HVS strains A11 and C488 are structurally divergent, they were both capable of inducing the lytic replication cycle in this model of HVS latency.
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Affiliation(s)
- D J Goodwin
- Molecular Medicine Unit, St. James's University Hospital, University of Leeds, Leeds LS9 7TF, United Kingdom
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41
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Kanamori M, Tajima M, Satoh Y, Hoshikawa Y, Miyazawa Y, Okinaga K, Kurata T, Sairenji T. Differential effect of TPA on cell growth and Epstein-Barr virus reactivation in epithelial cell lines derived from gastric tissues and B cell line Raji. Virus Genes 2001; 20:117-25. [PMID: 10872872 DOI: 10.1023/a:1008110312661] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We characterized the cell growth and Epstein-Barr virus (EBV) reactivation for EBV infected epithelial cell lines, GT38, GT39, and GTC-4 using 12-O-tetradecanoylphorbol-13-acetate (TPA). These cell lines grew similarly in liquid medium, and formed colonies in soft agar. The cell growth was inhibited with TPA, dose-dependently in liquid medium. The colony formation was enhanced with low concentrations of TPA, but was inhibited with high concentrations. The latent EBV was reactivated with high concentrations of TPA as shown by the expression of EBV BZLF1 gene product ZEBRA. The effects of TPA on GTC-4 were compared with a Burkitt's lymphoma cell line Raji. The mode of actions of TPA in GTC-4 was different from Raji in terms of cell growth and EBV reactivation. The effective concentrations of TPA for cell growth inhibition and EBV reactivation were higher in Raji than GTC-4. Cell cycle analysis showed that TPA (20 ng/ml) induced cell cycle arrest to Raji but not to GTC-4; however, the rate of trypan blue stained cells increased in the TPA treated GTC-4 but not Raji. These results demonstrated that TPA affects differentially for the stimulation and inhibition of cell growth, and also EBV reactivation depends on TPA concentrations and cell types.
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Affiliation(s)
- M Kanamori
- Department of Biosignaling, School of Life Science, Faculty of Medicine, Tottori University, Yonago, Japan
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42
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Kraus RJ, Mirocha SJ, Stephany HM, Puchalski JR, Mertz JE. Identification of a novel element involved in regulation of the lytic switch BZLF1 gene promoter of Epstein-Barr virus. J Virol 2001; 75:867-77. [PMID: 11134300 PMCID: PMC113983 DOI: 10.1128/jvi.75.2.867-877.2001] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) is a human herpesvirus capable of establishing a latent state in B lymphocytes. EBV's BZLF1 gene product plays a central role in regulating the switch from latency to productive infection. Here, we identify a sequence element, 5'-CAGGTA-3', called ZV, located at nucleotides -17 to -12 relative to the transcription initiation site of the BZLF1 promoter. ZV sequence-specifically binds a cellular nuclear factor(s), ZVR. ZVR DNA-binding activity was present in the EBV-negative B-lymphocytic cell line DG75, the EBV-positive B-lymphocytic cell lines GG68 and 721, the cervical cell line C33A, and the kidney cell line CV-1 but not in the breast carcinoma cell line MCF-7. Mutations in ZV that relieve binding of ZVR lead to a two- to fourfold increase in basal expression of the BZLF1 promoter in DG75, C33A, and CV-1 cells. The same mutants exhibited a 40- to 180-fold increase in tetradecanoyl phorbol acetate-ionomycin-induced expression in DG75 cells and a 22-fold increase in C33A cells. Thus, ZVR functions as a regulator of the BZLF1 promoter, repressing transcription when bound to the ZV site in the absence of inducers. No differences in basal or induced transcription between wild-type and ZV mutant BZLF1 promoters were observed in ZVR-negative MCF-7 cells. ZVR failed to bind any of the previously identified negative regulatory elements within the BZLF1 promoter. We conclude that ZV functions as an important regulatory element of the BZLF1 promoter, with ZVR likely playing important roles in the maintenance of latency and reactivation of EBV.
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Affiliation(s)
- R J Kraus
- McArdle Laboratory for Cancer Research, University of Wisconsin Medical School, Madison, Wisconsin 53706-1599, USA
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43
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Park J, Seo T, Hwang S, Lee D, Gwack Y, Choe J. The K-bZIP protein from Kaposi's sarcoma-associated herpesvirus interacts with p53 and represses its transcriptional activity. J Virol 2000; 74:11977-82. [PMID: 11090200 PMCID: PMC112483 DOI: 10.1128/jvi.74.24.11977-11982.2000] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2000] [Accepted: 09/25/2000] [Indexed: 11/20/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus that has been implicated in the pathogenesis of Kaposi's sarcoma. KSHV encodes K-bZIP (open reading frame K8), a protein that belongs to the basic region-leucine zipper (bZIP) family of transcription factors. Here we show that K-bZIP associates with the cellular transcription factor p53 directly in vitro and in vivo. This interaction requires the bZIP domain of K-bZIP and the carboxy-terminal region (amino acids 300 to 393) of p53. We also show that K-bZIP represses the transcriptional activity of p53 which is required for apoptosis of the host cell. These results imply that K-bZIP blocks p53-mediated host cell death through its interaction with p53.
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Affiliation(s)
- J Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejeon 305-701, Korea
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44
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Prang N, Wolf H, Schwarzmann F. Latency of Epstein-Barr virus is stabilized by antisense-mediated control of the viral immediate-early gene BZLF-1. J Med Virol 1999; 59:512-9. [PMID: 10534735 DOI: 10.1002/(sici)1096-9071(199912)59:4<512::aid-jmv15>3.0.co;2-b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The ability of the Epstein-Barr virus (EBV) to avoid lytic replication and to establish a latent infection in B-lymphocytes is fundamental for its lifelong persistence and the pathogenesis of various EBV-associated diseases. The viral immediate-early gene BZLF-1 plays a key role for the induction of lytic replication and its activity is strictly regulated on different levels of gene expression. Recently, it was demonstrated that BZLF-1 is also controlled by a posttranscriptional mechanism. Transient synthesis of a mutated competitor RNA saturated this mechanism and caused both expression of the BZLF-1 protein and the induction of lytic viral replication. Using short overlapping fragments of the competitor, it is shown that this control acts on the unspliced primary transcript. RT-PCR demonstrated unspliced BZLF-1 RNA in latently infected B-lymphocytes in the absence of BZLF-1 protein. Due to the complementarity of the gene BZLF-1 and the latency-associated gene EBNA-1 on the opposite strand of the genome, we propose an antisense-mediated mechanism. RNase protection assays demonstrated transcripts in antisense orientation to the BZLF-1 transcript during latency, which comprise a comparable constellation to other herpesviruses. A combined RNAse protection/RT-PCR assay detected the double-stranded hybrid RNA, consisting of the unspliced BZLF-1 transcript and a noncoding intron of the EBNA-1 gene. Binding of BZLF-1 transcripts is suggested to be an important backup control mechanism in addition to transcriptional regulation, stabilizing latency and preventing inappropriate lytic viral replication in vivo.
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Affiliation(s)
- N Prang
- Labor für Molekulare Onkologie, Munich, Germany
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45
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Ragoczy T, Miller G. Role of the epstein-barr virus RTA protein in activation of distinct classes of viral lytic cycle genes. J Virol 1999; 73:9858-66. [PMID: 10559298 PMCID: PMC113035 DOI: 10.1128/jvi.73.12.9858-9866.1999] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Initiation of the Epstein-Barr virus (EBV) lytic cycle is controlled by two immediate-early genes, BZLF1 and BRLF1. In certain epithelial and B-cell lines, their protein products, ZEBRA and Rta, stimulate their own expression, reciprocally stimulate each other's expression, and activate downstream viral targets. It has been difficult to examine the individual roles of these two transactivators in EBV-infected lymphocytes, as they are expressed simultaneously upon induction of the lytic cycle. Here we show that the Burkitt lymphoma cell line Raji represents an experimental system that allows the study of Rta's role in the lytic cycle of EBV in the absence and presence of ZEBRA. When expressed in Raji cells, exogenous Rta does not activate endogenous BZLF1 expression, yet Rta remains competent to transactivate certain downstream viral targets. Some genes, such as BaRF1, BMLF1, and a late gene, BLRF2, are maximally activated by Rta itself in the absence of detectable ZEBRA. The use of the Z(S186A) mutant form of ZEBRA, whose transactivation function is manifest only by coexpression of Rta, allows identification of a second class of lytic cycle genes, such as BMRF1 and BHRF1, that are activated in synergy by Rta and ZEBRA. It has already been documented that of the two activators, only ZEBRA stimulates the BRLF1 gene in Raji cells. Thus, there is a third class of viral genes activated by ZEBRA but not Rta. Moreover, ZEBRA exhibits an inhibitory effect on Rta's capacity to stimulate the late gene, BLRF2. Consequently ZEBRA may function to repress Rta's potential to activate some late genes. Raji cells thus allow delineation of the combinatorial roles of Rta and ZEBRA in control of several distinct classes of lytic cycle genes.
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Affiliation(s)
- T Ragoczy
- Departments Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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46
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Rodriguez A, Armstrong M, Dwyer D, Flemington E. Genetic dissection of cell growth arrest functions mediated by the Epstein-Barr virus lytic gene product, Zta. J Virol 1999; 73:9029-38. [PMID: 10516009 PMCID: PMC112935 DOI: 10.1128/jvi.73.11.9029-9038.1999] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Expression of the Epstein-Barr virus (EBV) latency-associated genes activates cell cycle progression and drives immortalization of the infected cell. In contrast, progression of the EBV replication program occurs most efficiently in growth-arrested cells. Previous studies showed that the EBV-encoded immediate-early transcription factor, Zta, can induce expression of the cyclin-dependent kinase inhibitors, p21 and p27, the tumor suppressor, p53, and cell growth arrest. Moreover, Zta-mediated induction of growth arrest occurs independently of its transcriptional transactivation function. Here we show that substitution of Zta's basic DNA binding domain with the analogous region of the Zta homologue, c-Fos, abrogates Zta's ability to induce growth arrest and to induce p21, p27, or p53 expression, suggesting that protein-protein interactions between this region of Zta and key cell cycle control proteins are involved in signaling cell cycle arrest. We also show that despite the crucial role for Zta's basic domain in eliciting cell growth arrest, its amino terminus is required for efficient induction of p27 and it modulates the level of p53 induction. Last, we provide evidence that Zta-mediated inductions of p21, p27, and p53 occur, at least in part, through distinct pathways. Therefore, Zta interacts with multiple growth arrest pathways, a property which may have evolved partly as a means to ensure that lytic replication occurs in a growth-arrested setting in multiple different tissues in various states of differentiation.
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Affiliation(s)
- A Rodriguez
- Harvard University, Boston, Massachusetts 02115, USA
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47
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Sarid R, Olsen SJ, Moore PS. Kaposi's sarcoma-associated herpesvirus: epidemiology, virology, and molecular biology. Adv Virus Res 1999; 52:139-232. [PMID: 10384236 DOI: 10.1016/s0065-3527(08)60299-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- R Sarid
- Division of Epidemiology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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48
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Francis A, Ragoczy T, Gradoville L, Heston L, El-Guindy A, Endo Y, Miller G. Amino acid substitutions reveal distinct functions of serine 186 of the ZEBRA protein in activation of early lytic cycle genes and synergy with the Epstein-Barr virus R transactivator. J Virol 1999; 73:4543-51. [PMID: 10233912 PMCID: PMC112494 DOI: 10.1128/jvi.73.6.4543-4551.1999] [Citation(s) in RCA: 43] [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
The ZEBRA protein mediates the switch between the latent and lytic life cycles of Epstein-Barr virus. Z(S186A), a point mutant in ZEBRA's basic domain in which serine 186 is changed to alanine, is unable to induce expression of lytic cycle mRNAs or proteins from the latent EBV genome even though it retains the ability to activate transcription from reporters bearing known ZEBRA-responsive promoters (A. L. Francis et al., J. Virol. 71:3054-3061, 1997). We now describe three distinct phenotypes of ZEBRA mutants bearing different amino acid substitutions at S186. These phenotypes are based on the capacity of the mutants to activate expression of the BRLF1 and BMRF1 genes, which are targets of ZEBRA's action, and to synergize with the BRLF1 gene product Rta (R transactivator) in activating expression of downstream genes. One mutant class, represented by Z(S186T), was similar to the wild type, although reduced in the capacity to activate BRLF1 and BMRF1 early lytic cycle genes from the latent virus. A second class, represented by Z(S186C) and Z(S186G), was impaired in transcriptional activation, unable to activate early lytic cycle products from the latent virus, and not rescued by overexpression of Rta. A third class, Z(S186A), although unable by itself to activate BRLF1 or other lytic cycle genes, synergized with Rta. Rta rescued the capacity of Z(S186A) to activate the BMRF1 early lytic cycle gene from the latent virus. All mutant classes bound to DNA in vitro, although their capacity to bind to different ZEBRA response elements varied. Serine 186 of ZEBRA is a critical residue that is required for the distinct activities of induction of BRLF1 expression and for synergy with Rta. Since only Z(S186T) among the mutants behaved similarly to the wild type, activation of BRLF1 likely requires phosphorylation of S186. However, since Z(S186A) could synergize with Rta, synergy with Rta does not appear to be dependent on phosphorylation of S186. S186 likely mediates DNA recognition on the BRLF1 promoter in the context of the latent virus, protein-protein interactions, or both. The Z(S186) mutants define the amino acid side chains required for these functions.
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Affiliation(s)
- A Francis
- Departments of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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49
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Labrecque LG, Xue SA, Kazembe P, Phillips J, Lampert I, Wedderburn N, Griffin BE. Expression of Epstein-Barr virus lytically related genes in African Burkitt's lymphoma: correlation with patient response to therapy. Int J Cancer 1999; 81:6-11. [PMID: 10077144 DOI: 10.1002/(sici)1097-0215(19990331)81:1<6::aid-ijc2>3.0.co;2-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A study on the Epstein-Barr virus (EBV)-associated malignancy (endemic) Burkitt's lymphoma (BL) was initiated on fine-needle-aspiration biopsies from 46 proven BL cases in Malawi. Gene expression that might correlate with patient serology (where high levels of antibodies to lytically related genes are commonly observed) was explored. In two-thirds of the cases, we identified the EBV BZLF1 replication activator intermediate early protein ZEBRA in varying quantities and to varying extents in cells by immuno-cytochemistry. The early lytic-cycle gene transcript BHLF1 was assessed positively by solid-phase hybridisation in over half of the same tumours. Evidence of transcription of these genes was confirmed on a smaller number of surgically removed fresh biopsies by RT-PCR. We asked whether our findings, which are generally counter to the established notion that EBV gene expression in BLs is restricted to the latent function, EBNA1, might offer some explanation for the differential responses to chemotherapy observed among African patients. Where the duration of follow-up was sufficient to assign the cases (37 in number) to one of 3 categories, namely, complete, partial or no response, a significant correlation between expression of the viral function ZEBRA and a positive patient response to treatment was found. Lack of this was associated with poor prognosis. Clinical data and EBV gene expression results support the postulate of subgroups of African BLs, the intermediate early antigen providing a marker of potential use in patient management.
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Affiliation(s)
- L G Labrecque
- Department of Infectious Diseases (Virology), Imperial College School of Medicine, Hammersmith Hospital, London, UK
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50
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Serio TR, Cahill N, Prout ME, Miller G. A functionally distinct TATA box required for late progression through the Epstein-Barr virus life cycle. J Virol 1998; 72:8338-43. [PMID: 9733880 PMCID: PMC110205 DOI: 10.1128/jvi.72.10.8338-8343.1998] [Citation(s) in RCA: 43] [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
During EBV infection, lytic DNA replication activates late gene expression in trans via an uncharacterized pathway. In this study, we mapped the target of this regulatory cascade to a variant TATA box (TATTAAA) and the 3' flanking region within the core promoter of the BcLF1 gene. The inherent late activity of this core promoter is, surprisingly, disrupted by a heterologous enhancer, suggesting that late gene expression is regulated through core promoter sequences located in a transcriptionally inert environment.
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Affiliation(s)
- T R Serio
- Department of Molecular Biophysics and Biochemistry, New Haven, Connecticut 06520, USA
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