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Immunosuppressive Tumor Microenvironment and Immunotherapy of Epstein–Barr Virus-Associated Malignancies. Viruses 2022; 14:v14051017. [PMID: 35632758 PMCID: PMC9146158 DOI: 10.3390/v14051017] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/03/2022] [Accepted: 05/09/2022] [Indexed: 02/07/2023] Open
Abstract
The Epstein–Barr virus (EBV) can cause different types of cancer in human beings when the virus infects different cell types with various latent patterns. EBV shapes a distinct and immunosuppressive tumor microenvironment (TME) to its benefit by influencing and interacting with different components in the TME. Different EBV-associated malignancies adopt similar but slightly specific immunosuppressive mechanisms by encoding different EBV products to escape both innate and adaptive immune responses. Strategies reversing the immunosuppressive TME of EBV-associated malignancies have been under evaluation in clinical practice. As the interactions among EBV, tumor cells, and TME are intricate, in this review, we mainly discuss the epidemiology of EBV, the life cycle of EBV, the cellular and molecular composition of TME, and a landscape of different EBV-associated malignancies and immunotherapy by targeting the TME.
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Nečasová I, Stojaspal M, Motyčáková E, Brom T, Janovič T, Hofr C. Transcriptional regulators of human oncoviruses: structural and functional implications for anticancer therapy. NAR Cancer 2022; 4:zcac005. [PMID: 35252867 PMCID: PMC8892037 DOI: 10.1093/narcan/zcac005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 02/04/2022] [Accepted: 02/15/2022] [Indexed: 11/26/2022] Open
Abstract
Transcription is often the first biosynthetic event of viral infection. Viruses produce preferentially viral transcriptional regulators (vTRs) essential for expressing viral genes and regulating essential host cell proteins to enable viral genome replication. As vTRs are unique viral proteins that promote the transcription of viral nucleic acid, vTRs interact with host proteins to suppress detection and immune reactions to viral infection. Thus, vTRs are promising therapeutic targets that are sequentially and structurally distinct from host cell proteins. Here, we review vTRs of three human oncoviruses: HBx of hepatitis B virus, HBZ of human T-lymphotropic virus type 1, and Rta of Epstein–Barr virus. We present three cunningly exciting and dangerous transcription strategies that make viral infections so efficient. We use available structural and functional knowledge to critically examine the potential of vTRs as new antiviral-anticancer therapy targets. For each oncovirus, we describe (i) the strategy of viral genome transcription; (ii) vTRs’ structure and binding partners essential for transcription regulation; and (iii) advantages and challenges of vTR targeting in antiviral therapies. We discuss the implications of vTR regulation for oncogenesis and perspectives on developing novel antiviral and anticancer strategies.
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Affiliation(s)
- Ivona Nečasová
- Institute of Biophysics of the Czech Academy of Sciences, Scientific Incubator, Královopolská 135, Brno 612 65, Czech Republic
| | - Martin Stojaspal
- Institute of Biophysics of the Czech Academy of Sciences, Scientific Incubator, Královopolská 135, Brno 612 65, Czech Republic
| | - Edita Motyčáková
- Institute of Biophysics of the Czech Academy of Sciences, Scientific Incubator, Královopolská 135, Brno 612 65, Czech Republic
| | - Tomáš Brom
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, Brno 625 00, Czech Republic
| | - Tomáš Janovič
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, Brno 625 00, Czech Republic
| | - Ctirad Hofr
- Institute of Biophysics of the Czech Academy of Sciences, Scientific Incubator, Královopolská 135, Brno 612 65, Czech Republic
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Bauer M, Jasinski-Bergner S, Mandelboim O, Wickenhauser C, Seliger B. Epstein-Barr Virus-Associated Malignancies and Immune Escape: The Role of the Tumor Microenvironment and Tumor Cell Evasion Strategies. Cancers (Basel) 2021; 13:cancers13205189. [PMID: 34680337 PMCID: PMC8533749 DOI: 10.3390/cancers13205189] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/06/2021] [Accepted: 10/11/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary The Epstein–Barr virus, also termed human herpes virus 4, is a human pathogenic double-stranded DNA virus. It is highly prevalent and has been linked to the development of 1–2% of cancers worldwide. EBV-associated malignancies encompass various structural and epigenetic alterations. In addition, EBV-encoded gene products and microRNAs interfere with innate and adaptive immunity and modulate the tumor microenvironment. This review provides an overview of the characteristic features of EBV with a focus on the intrinsic and extrinsic immune evasion strategies, which contribute to EBV-associated malignancies. Abstract The detailed mechanisms of Epstein–Barr virus (EBV) infection in the initiation and progression of EBV-associated malignancies are not yet completely understood. During the last years, new insights into the mechanisms of malignant transformation of EBV-infected cells including somatic mutations and epigenetic modifications, their impact on the microenvironment and resulting unique immune signatures related to immune system functional status and immune escape strategies have been reported. In this context, there exists increasing evidence that EBV-infected tumor cells can influence the tumor microenvironment to their own benefit by establishing an immune-suppressive surrounding. The identified mechanisms include EBV gene integration and latent expression of EBV-infection-triggered cytokines by tumor and/or bystander cells, e.g., cancer-associated fibroblasts with effects on the composition and spatial distribution of the immune cell subpopulations next to the infected cells, stroma constituents and extracellular vesicles. This review summarizes (i) the typical stages of the viral life cycle and EBV-associated transformation, (ii) strategies to detect EBV genome and activity and to differentiate various latency types, (iii) the role of the tumor microenvironment in EBV-associated malignancies, (iv) the different immune escape mechanisms and (v) their clinical relevance. This gained information will enhance the development of therapies against EBV-mediated diseases to improve patient outcome.
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Affiliation(s)
- Marcus Bauer
- Department of Pathology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 14, 06112 Halle (Saale), Germany; (M.B.); (C.W.)
| | - Simon Jasinski-Bergner
- Department of Medical Immunology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 2, 06112 Halle (Saale), Germany;
| | - Ofer Mandelboim
- Department of Immunology, Faculty of Medicine, The Hebrew University of Jerusalem, En Kerem, P.O. Box 12271, Jerusalem 91120, Israel;
| | - Claudia Wickenhauser
- Department of Pathology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 14, 06112 Halle (Saale), Germany; (M.B.); (C.W.)
| | - Barbara Seliger
- Department of Medical Immunology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 2, 06112 Halle (Saale), Germany;
- Fraunhofer Institute for Cell Therapy and Immunology, Perlickstr. 1, 04103 Leipzig, Germany
- Correspondence: ; Tel.: +49-(345)-557-1357
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Liu W, Li H, Sheng H, Liu X, Chi P, Wang X, Mao M. A Randomized Controlled Trial on Evaluation of Plasma Epstein-Barr Virus Biomarker for Early Diagnosis in Patients With Nasopharyngeal Carcinoma. Adv Ther 2020; 37:4280-4290. [PMID: 32780356 DOI: 10.1007/s12325-020-01461-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Early diagnosis of nasopharyngeal carcinoma (NPC) remains a major problem in Southern China. Epstein-Barr virus (EBV) biomarkers have been widely used in NPC screening. This study aims to evaluate the early diagnostic performances of individual EBV biomarkers in NPC. METHODS The levels of EBV biomarkers-IgA antibodies against EBV nuclear antigen 1 (EBNA1-IgA), EBV capsid antigen (VCA-IgA), EBV early antigen (EA-IgA), EBV BZLF1 transcription activator protein (Zta-IgA) and IgG antibodies against EBV BRLF1 transcription activator protein (Rta-IgG)-from 106 NPC patients (stage I and II) and 150 normal subjects were measured. VCA-IgA and EA-IgA were detected by immunofluorescence assay (IFA), EBNA1-IgA, Rta-IgG and Zta-IgA were measure by enzyme-linked immunosorbent assay (ELISA), and EBV DNA was detected by qPCR. Statistical analyses of a single index were conducted to evaluate the significance of NPC early diagnosis and TNM classification. RESULTS The level of EBNA1-IgA, EBV DNA, VCA-IgA, EA-IgA, Rta-IgG and Zta-IgA in early-stage NPC was significantly higher than in healthy controls (all P < 0.001). EBNA1-IgA yielded the biggest area under the curve (AUC) of 0.962 in distinguishing early-stage NPC patients from the normal subjects, with a sensitivity of 91.5% and a specificity of 98.7%. However, EBV biomarker levels were not associated with tumor size (all P > 0.050), whereas four biomarker levels (EBNA1-IgA, EBV DNA, VCA-IgA, EA-IgA) were related to lymph node metastasis (N0 and N1-2), among which EBNA1-IgA and EBV DNA showed good performance. Finally, high correlation was found between VCA-IgA and EA-IgA (r > 0.800). CONCLUSION A single EBNA1-IgA exhibits excellent discrimination performance in early diagnosis of NPC and could become a promising marker for NPC screening.
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Affiliation(s)
- Wen Liu
- Department of Laboratory Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Huilan Li
- Department of Laboratory Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Hui Sheng
- Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Xiaohua Liu
- Department of Laboratory Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Peidong Chi
- Department of Laboratory Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Xueping Wang
- Department of Laboratory Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China.
| | - Minjie Mao
- Department of Laboratory Medicine, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-Sen University Cancer Center, Guangzhou, China.
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Watson G, Ronai ZA, Lau E. ATF2, a paradigm of the multifaceted regulation of transcription factors in biology and disease. Pharmacol Res 2017; 119:347-357. [PMID: 28212892 PMCID: PMC5457671 DOI: 10.1016/j.phrs.2017.02.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/01/2017] [Accepted: 02/02/2017] [Indexed: 01/16/2023]
Abstract
Stringent transcriptional regulation is crucial for normal cellular biology and organismal development. Perturbations in the proper regulation of transcription factors can result in numerous pathologies, including cancer. Thus, understanding how transcription factors are regulated and how they are dysregulated in disease states is key to the therapeutic targeting of these factors and/or the pathways that they regulate. Activating transcription factor 2 (ATF2) has been studied in a number of developmental and pathological conditions. Recent findings have shed light on the transcriptional, post-transcriptional, and post-translational regulatory mechanisms that influence ATF2 function, and thus, the transcriptional programs coordinated by ATF2. Given our current knowledge of its multiple levels of regulation and function, ATF2 represents a paradigm for the mechanistic complexity that can regulate transcription factor function. Thus, increasing our understanding of the regulation and function of ATF2 will provide insights into fundamental regulatory mechanisms that influence how cells integrate extracellular and intracellular signals into a genomic response through transcription factors. Characterization of ATF2 dysfunction in the context of pathological conditions, particularly in cancer biology and response to therapy, will be important in understanding how pathways controlled by ATF2 or other transcription factors might be therapeutically exploited. In this review, we provide an overview of the currently known upstream regulators and downstream targets of ATF2.
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Affiliation(s)
- Gregory Watson
- Department of Tumor Biology and Program in Chemical Biology and Molecular Medicine, H. Lee Moffitt Cancer Center, Tampa, FL, USA
| | - Ze'ev A Ronai
- Tumor Initiation and Maintenance Program, Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA; Technion Integrated Cancer Center, Rappaport Faculty of Medicine, Technion, Haifa, 3109601, Israel
| | - Eric Lau
- Department of Tumor Biology and Program in Chemical Biology and Molecular Medicine, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
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Huang HH, Chen CS, Wang WH, Hsu SW, Tsai HH, Liu ST, Chang LK. TRIM5α Promotes Ubiquitination of Rta from Epstein-Barr Virus to Attenuate Lytic Progression. Front Microbiol 2017; 7:2129. [PMID: 28105027 PMCID: PMC5214253 DOI: 10.3389/fmicb.2016.02129] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/16/2016] [Indexed: 12/04/2022] Open
Abstract
Replication and transcription activator (Rta), a key protein expressed by Epstein–Barr virus (EBV) during the immediate-early stage of the lytic cycle, is responsible for the activation of viral lytic genes. In this study, GST-pulldown and coimmunoprecipitation assays showed that Rta interacts in vitro and in vivo with TRIM5α, a host factor known to be involved in the restriction of retroviral infections. Confocal microscopy results revealed that Rta colocalizes with TRIM5α in the nucleus during lytic progression. The interaction involves 190 amino acids in the N-terminal of Rta and the RING domain in TRIM5α, and it was further found that TRIM5α acts as an E3 ubiquitin ligase to promote Rta ubiquitination. Overexpression of TRIM5α reduced the transactivating capabilities of Rta, while reducing TRIM5α expression enhanced EBV lytic protein expression and DNA replication. Taken together, these results point to a critical role for TRIM5α in attenuating EBV lytic progression through the targeting of Rta for ubiquitination, and suggest that the restrictive capabilities of TRIM5α may go beyond retroviral infections.
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Affiliation(s)
- Hsiang-Hung Huang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University Taipei, Taiwan
| | - Chien-Sin Chen
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University Taipei, Taiwan
| | - Wen-Hung Wang
- Department of Internal Medicine, Kaohsiung Medical University Hospital Kaohsiung, Taiwan
| | - Shih-Wei Hsu
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University Taipei, Taiwan
| | - Hsiao-Han Tsai
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University Taipei, Taiwan
| | - Shih-Tung Liu
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University Taoyuan, Taiwan
| | - Li-Kwan Chang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University Taipei, Taiwan
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Zhang W, Zhang ZZ, Tang LY, Lin Y, Su FX, Xie XM, Su XF, Ren ZF. Genetic variants in EBV reactivation-related genes and the risk and survival of breast cancer. Tumour Biol 2016; 37:8337-47. [PMID: 26729199 DOI: 10.1007/s13277-015-4562-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/01/2015] [Indexed: 12/27/2022] Open
Abstract
Tumor susceptibility gene 101 (TSG101) and activating transcription factor 2 (ATF2) have been suggested to involve in the reactivation of EBV which has implications in the development and progression of breast cancer. Therefore, the polymorphisms of TSG101 and ATF2 may associate with breast cancer risk and prognosis. A case-control study with 1551 breast cancer cases and 1605 age-matched controls were conducted in Guangzhou, China. We have also successfully followed up 1168 cases until December 31, 2014. The variant allele of TSG101 rs2292179 was associated with a non-significant reduced risk of breast cancer, particularly among women with BMI < 24 (kg/m(2)) (P for interaction <0.05). For ATF2 rs3845744, the variant allele was also associated with a significantly reduced breast cancer risk [odds ratio (OR) (95 % confidence interval (CI)) 0.86 (0.74∼1.00)], and the association occurred among only postmenopausal women [OR (95 % CI) 0.69 (0.54∼0.88)] (P for interaction <0.05). Breast cancer risk was further reduced with the increasing numbers of the variant G alleles of the two polymorphisms (P for trend <0.05). We did not find an overall association of the two loci with breast cancer prognosis, while the hazard ratios of the two loci (AG/GG vs. AA) were significantly higher among postmenopausal women than premenopausal women (P = 0.046, 0.016 for TSG101 rs2292179 and ATF2 rs3845744, respectively). In summary, the variant alleles of TSG101 rs2292179 and ATF2 rs3845744 were associated with a reduced risk of breast cancer, particularly for subjects with BMI <24 (kg/m(2)) and postmenopausal women, respectively. The two SNPs and menopausal status may have a significant interaction on breast cancer progression.
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Affiliation(s)
- Wei Zhang
- The School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Zheng-Zheng Zhang
- The School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
- Aviation Hygiene Management Division, China Southern Airlines Company Limited, 9/F, Kangda Building, 278 Airport Road, Guangzhou, China
| | - Lu-Ying Tang
- The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Ying Lin
- The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Feng-Xi Su
- The Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510120, China
| | - Xiao-Ming Xie
- The Sun Yat-Sen University Cancer Center, Guangzhou, 510080, China
| | - Xue-Fen Su
- School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
| | - Ze-Fang Ren
- The School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China.
- Department of Statistics and Epidemiology, Guangzhou Key Laboratory of Environmental Pollution and Health Risk Assessment, School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou, 510080, China.
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Yang YC, Feng TH, Chen TY, Huang HH, Hung CC, Liu ST, Chang LK. RanBPM regulates Zta-mediated transcriptional activity in Epstein–Barr virus. J Gen Virol 2015; 96:2336-2348. [DOI: 10.1099/vir.0.000157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Ya-Chun Yang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Tzu-Hui Feng
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Tse-Yao Chen
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Hsiang-Hung Huang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Chen-Chia Hung
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Taoyuan, 333, Taiwan, ROC
| | - Shih-Tung Liu
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Taoyuan, 333, Taiwan, ROC
| | - Li-Kwan Chang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan, ROC
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Hung CC, Kuo CW, Wang WH, Chang TH, Chang PJ, Chang LK, Liu ST. Transcriptional activation of Epstein-Barr virus BRLF1 by USF1 and Rta. J Gen Virol 2015; 96:2855-2866. [PMID: 26297580 DOI: 10.1099/jgv.0.000230] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During its lytic cycle, Epstein-Barr virus (EBV) expresses Rta, a factor encoded by BRLF1 that activates the transcription of viral lytic genes. We found that upstream stimulating factor (USF) binds to E1, one of the five E boxes located at - 79 in the BRLF1 promoter (Rp), to activate BRLF1 transcription. Furthermore, Rta was shown to interact with USF1 in coimmunoprecipitation and glutathione S-transferase (GST)-pulldown assays, and confocal laser-scanning microscopy further confirmed that these two proteins colocalize in the nucleus. Rta was also found to bind with the E1 sequence in a biotin-labelled E1 probe, but only in the presence of USF1, suggesting that these two proteins likely form a complex on E1. We subsequently constructed p188mSZ, a reporter plasmid that contained the sequence from - 188 to +5 in Rp, within which the Sp1 site and Zta response element were mutated. In EBV-negative Akata cells cotransfected with p188mSZ and plasmids expressing USF1 and Rta, synergistic activation of Rp transcription was observed. However, after mutating the E1 sequence in p188mSZ, USF1 and Rta were no longer able to transactivate Rp, indicating that Rta autoregulates BRLF1 transcription via its interaction with USF1 on E1. This study showed that pUSF1 transfection after EBV lytic induction in P3HR1 cells increases Rta expression, indicating that USF1 activates Rta expression after the virus enters the lytic cycle. Together, these results reveal a novel mechanism by which USF interacts with Rta to promote viral lytic development, and provide additional insight into the viral-host interactions of EBV.
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Affiliation(s)
- Chen-Chia Hung
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Kwei-Shan, Taoyuan 33302, Taiwan, ROC
| | - Chung-Wen Kuo
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Kwei-Shan, Taoyuan 33302, Taiwan, ROC
| | - Wen-Hung Wang
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Kwei-Shan, Taoyuan 33302, Taiwan, ROC
| | - Tzu-Hsuan Chang
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Kwei-Shan, Taoyuan 33302, Taiwan, ROC
| | - Pey-Jium Chang
- Graduate Institute of Clinical Medical Sciences, Chang-Gung University, Kwei-Shan, Taoyuan 33302, Taiwan, ROC
| | - Li-Kwan Chang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei 10617, Taiwan, ROC
| | - Shih-Tung Liu
- Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, Kwei-Shan, Taoyuan 33302, Taiwan, ROC.,Department of Medical Research, Chang-Gung Memorial Hospital Chiayi Branch, Chiayi 61363, Taiwan, ROC
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Cellular differentiation regulator BLIMP1 induces Epstein-Barr virus lytic reactivation in epithelial and B cells by activating transcription from both the R and Z promoters. J Virol 2014; 89:1731-43. [PMID: 25410866 DOI: 10.1128/jvi.02781-14] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Epstein-Barr virus (EBV) maintains a lifelong latent infection within a subset of its host's memory B cells, while lytic EBV replication takes place in plasma cells and differentiated epithelial cells. Therefore, cellular transcription factors, such as BLIMP1, that are key mediators of differentiation likely contribute to the EBV latent-to-lytic switch. Previous reports showed that ectopic BLIMP1 expression induces reactivation in some EBV-positive (EBV(+)) B-cell lines and transcription from Zp, with all Z(+) cells in oral hairy leukoplakia being BLIMP1(+). Here, we examined BLIMP1's role in inducing EBV lytic gene expression in numerous EBV(+) epithelial and B-cell lines and activating transcription from Rp. BLIMP1 addition was sufficient to induce reactivation in latently infected epithelial cells derived from gastric cancers, nasopharyngeal carcinomas, and normal oral keratinocytes (NOK) as well as some, but not all B-cell lines. BLIMP1 strongly induced transcription from Rp as well as Zp, with there being three or more synergistically acting BLIMP1-responsive elements (BRE) within Rp. BLIMP1's DNA-binding domain was required for reactivation, but BLIMP1 did not directly bind the nucleotide (nt) -660 Rp BRE. siRNA knockdown of BLIMP1 inhibited 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced lytic reactivation in NOK-Akata cells, cells that can be reactivated by R, but not Z. Thus, we conclude that BLIMP1 expression is both necessary and sufficient to induce EBV lytic replication in many (possibly all) EBV(+) epithelial-cell types, but in only a subset of EBV(+) B-cell types; it does so, at least in part, by strongly activating expression of both EBV immediately early genes, BZLF1 and BRLF1. IMPORTANCE This study is the first one to show that the cellular transcription factor BLIMP1, a key player in both epithelial and B-cell differentiation, induces reactivation of the oncogenic herpesvirus Epstein-Barr virus (EBV) out of latency into lytic replication in a variety of cancerous epithelial cell types as well as in some, but not all, B-cell types that contain this virus in a dormant state. The mechanism by which BLIMP1 does so involves strongly turning on expression of both of the immediate early genes of the virus, probably by directly acting upon the promoters as part of protein complexes or indirectly by altering the expression or activities of some cellular transcription factors and signaling pathways. The fact that EBV(+) cancers usually contain mostly undifferentiated cells may be due in part to these cells dying from lytic EBV infection when they differentiate and express wild-type BLIMP1.
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