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Lin KM, Weng LF, Chen SYJ, Lin SJ, Tsai CH. Upregulation of IQGAP2 by EBV transactivator Rta and its influence on EBV life cycle. J Virol 2023; 97:e0054023. [PMID: 37504571 PMCID: PMC10506479 DOI: 10.1128/jvi.00540-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 06/09/2023] [Indexed: 07/29/2023] Open
Abstract
Epstein-Barr virus (EBV) is a human oncogenic γ-herpesvirus that establishes persistent infection in more than 90% of the world's population. EBV has two life cycles, latency and lytic replication. Reactivation of EBV from latency to the lytic cycle is initiated and controlled by two viral immediate-early transcription factors, Zta and Rta, encoded by BZLF1 and BRLF1, respectively. In this study, we found that IQGAP2 expression was elevated in EBV-infected B cells and identified Rta as a viral gene responsible for the IQGAP2 upregulation in both B cells and nasopharyngeal carcinoma cell lines. Mechanistically, we showed that Rta increases IQGAP2 expression through direct binding to the Rta-responsive element in the IQGAP2 promoter. We also demonstrated the direct interaction between Rta and IQGAP2 as well as their colocalization in the nucleus. Functionally, we showed that the induced IQGAP2 is required for the Rta-mediated Rta promoter activation in the EBV lytic cycle progression and may influence lymphoblastoid cell line clumping morphology through regulating E-cadherin expression. IMPORTANCE Elevated levels of antibodies against EBV lytic proteins and increased EBV DNA copy numbers in the sera have been reported in patients suffering from Burkitt's lymphoma, Hodgkin's lymphoma, and nasopharyngeal carcinoma, indicating that EBV lytic cycle progression may play an important role in the pathogenesis of EBV-associated diseases and highlighting the need for a more complete mechanistic understanding of the EBV lytic cycle. Rta acts as an essential transcriptional activator to induce lytic gene expression and thus trigger EBV reactivation. In this study, scaffolding protein IQGAP2 was found to be upregulated prominently following EBV infection via the direct binding of Rta to the RRE in the IQGAP2 promoter but not in response to other biological stimuli. Importantly, IQGAP2 was demonstrated to interact with Rta and promote the EBV lytic cycle progression. Suppression of IQGAP2 was also found to decrease E-cadherin expression and affect the clumping morphology of lymphoblastoid cell lines.
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Affiliation(s)
- Kai-Min Lin
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Li-Fang Weng
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Shi-Yo Jill Chen
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Sue-Jane Lin
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ching-Hwa Tsai
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Chua HH, Kameyama T, Mayeda A, Yeh TH. Epstein-Barr Virus Enhances Cancer-Specific Aberrant Splicing of TSG101 Pre-mRNA. Int J Mol Sci 2022; 23:ijms23052516. [PMID: 35269659 PMCID: PMC8910672 DOI: 10.3390/ijms23052516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/21/2022] [Accepted: 02/21/2022] [Indexed: 11/16/2022] Open
Abstract
Tumor viruses gain control of cellular functions when they infect and transform host cells. Alternative splicing is one of the cellular processes exploited by tumor viruses to benefit viral replication and support oncogenesis. Epstein-Barr virus (EBV) participates in a number of cancers, as reported mostly in nasopharyngeal carcinoma (NPC) and Burkitt lymphoma (BL). Using RT-nested-PCR and Northern blot analysis in NPC and BL cells, here we demonstrate that EBV promotes specific alternative splicing of TSG101 pre-mRNA, which generates the TSG101∆154-1054 variant though the agency of its viral proteins, such as EBNA-1, Zta and Rta. The level of TSG101∆154-1054 is particularly enhanced upon EBV entry into the lytic cycle, increasing protein stability of TSG101 and causing the cumulative synthesis of EBV late lytic proteins, such as VCA and gp350/220. TSG101∆154-1054-mediated production of VCA and gp350/220 is blocked by the overexpression of a translational mutant of TSG101∆154-1054 or by the depletion of full-length TSG101, which is consistent with the known role of the TSG101∆154-1054 protein in stabilizing the TSG101 protein. NPC patients whose tumor tissues express TSG101∆154-1054 have high serum levels of anti-VCA antibodies and high levels of viral DNA in their tumors. Our findings highlight the functional importance of TSG101∆154-1054 in allowing full completion of the EBV lytic cycle to produce viral particles. We propose that targeting EBV-induced TSG101 alternative splicing has broad potential as a therapeutic to treat EBV-associated malignancies.
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Affiliation(s)
- Huey-Huey Chua
- Department of Pediatrics, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 100226, Taiwan;
| | - Toshiki Kameyama
- Department of Physiology, School of Medicine, Fujita Health University, Toyoake 470-1192, Aichi, Japan;
| | - Akila Mayeda
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake 470-1192, Aichi, Japan
- Correspondence: (A.M.); (T.-H.Y.)
| | - Te-Huei Yeh
- Department of Otolaryngology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 100225, Taiwan
- Correspondence: (A.M.); (T.-H.Y.)
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Hwang SP, Huang LC, Wang WH, Lin MH, Kuo CW, Huang HH, Chang LK. Expression of Rta in B Lymphocytes during Epstein-Barr Virus Latency. J Mol Biol 2020; 432:5227-43. [PMID: 32710985 DOI: 10.1016/j.jmb.2020.07.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/29/2020] [Accepted: 07/20/2020] [Indexed: 11/21/2022]
Abstract
Rta of Epstein-Barr virus (EBV) is thought to be expressed only during the lytic cycle to promote the transcription of lytic genes. However, we found that Rta is expressed in EBV-infected B cells during viral latency, at levels detectable by immunoblot analysis. Latent Rta expression cannot be attributed to spontaneous lytic activation, as we observed that more than 90% of Akata, P3HR1, and 721 cells latently infected by EBV express Rta. We further found that Rta is sequestered in the nucleolus during EBV latency through its interaction with MCRS2, a nucleolar protein. When Rta is sequestered in the nucleolus, it no longer activates RNA polymerase II-driven transcription, thus explaining why Rta expression during latency does not transactivate EBV lytic genes. Additional experiments showed that Rta can bind to 18S rRNA and become incorporated into ribosomes, and a transient transfection experiment showed that Rta promotes translation from an mRNA reporter. These findings reveal that Rta has novel functions beyond transcriptional activation during EBV latency and may have interesting implications for the concept of EBV latency.
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Tung KL, Wu YT, Liu C, Lin SC, Wu CH, Wu SY, Chang Y, Lan YY. EBV Rta-induced IL-6 Promotes Migration of Bystander Tumor Cells Through IL-6R/JAK/STAT3 Pathway In Vitro. Anticancer Res 2020; 40:3255-3264. [PMID: 32487620 DOI: 10.21873/anticanres.14307] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/12/2020] [Accepted: 04/21/2020] [Indexed: 11/10/2022]
Abstract
BACKGROUND/AIM Rta, a transactivator of Epstein-Barr virus, is associated with progression of nasopharyngel carcinoma (NPC); however, its mechanism of contribution to the pathogenesis of NPC remains unclear. Interleukin-6 (IL-6), a tumor promoter, is detected in NPC. This in vitro study examined whether and how Rta promotes NPC progression by up-regulating IL-6. MATERIALS AND METHODS Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time PCR, ELISA, immunoblotting assays, reporter gene assays, and transwell migration assays were performed. RESULTS In NPC cells, Rta up-regulated IL-6 expression at the mRNA and protein levels, and the Rta's C-terminus was essential for promoter activation and expression of IL-6. The induction of IL-6 by Rta also required activation of extracellular signal-regulated kinase 1/2 and activator protein-1. Furthermore, IL-6 secreted from Rta-expressing NPC cells promoted migration of Rta-negative NPC cells by activating IL-6 receptor/Janus kinase/signal transducer and activator of transcription 3 pathway. CONCLUSION Rta contributes to progression of NPC cells through induction of IL-6 in vitro.
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Affiliation(s)
- Kuo-Lung Tung
- Department of Dental Technology, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan, R.O.C
| | - Yen-Ting Wu
- Department of Pathology, Golden Hospital, Pingtung, Taiwan, R.O.C
| | - Cheng Liu
- Department of Dental Technology, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan, R.O.C.,Department of Health and Beauty, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan, R.O.C
| | - Sheng-Chieh Lin
- Department of Dental Technology, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan, R.O.C
| | - Chin-Han Wu
- Department of Dental Technology, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan, R.O.C
| | - Shih-Yi Wu
- Department of Pathology, Golden Hospital, Pingtung, Taiwan, R.O.C
| | - Yao Chang
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan, R.O.C
| | - Yu-Yan Lan
- Department of Physical Therapy, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan, R.O.C.
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Huang HH, Wang WH, Feng TH, Chang LK. Rta is an Epstein-Barr virus tegument protein that improves the stability of capsid protein BORF1. Biochem Biophys Res Commun 2020; 523:773-779. [PMID: 31948747 DOI: 10.1016/j.bbrc.2020.01.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 01/05/2020] [Indexed: 11/30/2022]
Abstract
Rta, a key transcription factor expressed by Epstein-Barr virus (EBV), primarily acts to induce activation of the EBV lytic cycle. Interestingly, we observed from an immunogold assay that Rta is also present on the EBV capsid in the host cell nucleus, and a centrifugation study further revealed that Rta cofractionates with EBV virions. Importantly, cofractionated Rta showed similar properties as the EBV tegument protein, BGLF4. Glutathione S-transferase (GST)-pulldown and coimmunoprecipitation assays subsequently demonstrated that Rta directly interacts with the EBV capsid protein, BORF1. Rta was observed to colocalize with BORF1 in the nucleus during EBV lytic induction, and this interaction appears to influence BORF1 stability. Moreover, we found that BORF1 is modified by ubiquitin, and Rta reduces this ubiquitination. These results indicate that Rta may act as an inner tegument protein to improve EBV capsid stability and critical to viral infection.
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Affiliation(s)
- Hsiang-Hung Huang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Wen-Hung Wang
- Division of Infectious Disease, Department of Internal Medicine, Kaohsiung Medical University Chung-Ho Memorial Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Center for Tropical Medicine and Infectious Disease Research, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Tzu-Hui Feng
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Li-Kwan Chang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan.
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Gonzalez-Lopez O, DeCotiis J, Goyeneche C, Mello H, Vicente-Ortiz BA, Shin HJ, Driscoll KE, Du P, Palmeri D, Lukac DM. A herpesvirus transactivator and cellular POU proteins extensively regulate DNA binding of the host Notch signaling protein RBP-Jκ to the virus genome. J Biol Chem 2019; 294:13073-13092. [PMID: 31308175 DOI: 10.1074/jbc.ra118.007331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 07/10/2019] [Indexed: 12/11/2022] Open
Abstract
Reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) from latency requires the viral transactivator Rta to contact the host protein Jκ recombination signal-binding protein (RBP-Jκ or CSL). RBP-Jκ normally binds DNA sequence-specifically to determine the transcriptional targets of the Notch-signaling pathway, yet Notch alone cannot reactivate KSHV. We previously showed that Rta stimulates RBP-Jκ DNA binding to the viral genome. On a model viral promoter, this function requires Rta to bind to multiple copies of an Rta DNA motif (called "CANT" or Rta-c) proximal to an RBP-Jκ motif. Here, high-resolution ChIP/deep sequencing from infected primary effusion lymphoma cells revealed that RBP-Jκ binds nearly exclusively to different sets of viral genome sites during latency and reactivation. RBP-Jκ bound DNA frequently, but not exclusively, proximal to Rta bound to single, but not multiple, Rta-c motifs. To discover additional regulators of RBP-Jκ DNA binding, we used bioinformatics to identify cellular DNA-binding protein motifs adjacent to either latent or reactivation-specific RBP-Jκ-binding sites. Many of these cellular factors, including POU class homeobox (POU) proteins, have known Notch or herpesvirus phenotypes. Among a set of Rta- and RBP-Jκ-bound promoters, Rta transactivated only those that also contained POU motifs in conserved positions. On some promoters, POU factors appeared to inhibit RBP-Jκ DNA binding unless Rta bound to a proximal Rta-c motif. Moreover, POU2F1/Oct-1 expression was induced during KSHV reactivation, and POU2F1 knockdown diminished infectious virus production. Our results suggest that Rta and POU proteins broadly regulate DNA binding of RBP-Jκ during KSHV reactivation.
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Affiliation(s)
- Olga Gonzalez-Lopez
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103; Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Jennifer DeCotiis
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103; Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Corey Goyeneche
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103; Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Helena Mello
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103; Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Bryan Alexis Vicente-Ortiz
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Hye Jin Shin
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103; Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Kyla E Driscoll
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Peicheng Du
- High Performance and Research Computing, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Diana Palmeri
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - David M Lukac
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103; Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103.
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Chen LW, Hung CH, Wang SS, Yen JB, Liu AC, Hung YH, Chang PJ. Expression and regulation of the BKRF2, BKRF3 and BKRF4 genes of Epstein-Barr virus. Virus Res 2018; 256:76-89. [PMID: 30096410 DOI: 10.1016/j.virusres.2018.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/02/2018] [Accepted: 08/04/2018] [Indexed: 12/24/2022]
Abstract
The BKRF2, BKRF3 and BKRF4 genes of Epstein-Barr virus (EBV) are located close together in the viral genome, which encode glycoprotein L, uracil-DNA glycosylase and a tegument protein, respectively. Here, we demonstrate that the BKRF2 gene behaves as a true-late lytic gene, whereas the BKRF3 and BKRF4 genes belong to the early lytic gene family. Our results further reveal that both BKRF3 and BKRF4 promoters are new synergistic targets of Zta and Rta, two EBV latent-to-lytic switch transactivators. Multiple Rta- and Zta-responsive elements within the BKRF3 and BKRF4 promoters were identified and characterized experimentally. Importantly, we show that DNA methylation is absolutely required for activation of the BKRF4 promoter by Zta alone or in combination with Rta. Moreover, we find that sodium butyrate, an inducing agent of EBV reactivation, is capable of activating the BKRF4 promoter through a mechanism independent of Zta and Rta. Overall, our studies highlight the complexity of transcriptional regulation of lytic genes within the BKRF2-BKRF3-BKRF4 gene locus.
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Affiliation(s)
- Lee-Wen Chen
- Department of Respiratory Care, Chang-Gung University of Science and Technology, Chiayi 61363, Taiwan; Department of Pediatric Surgery, Chang-Gung Memorial Hospital, Chiayi 61363, Taiwan
| | - Chien-Hui Hung
- Graduate Institute of Clinical Medical Sciences, Chang-Gung University, Taoyuan 33302, Taiwan
| | - Shie-Shan Wang
- Department of Pediatric Surgery, Chang-Gung Memorial Hospital, Chiayi 61363, Taiwan; School of Traditional Chinese Medicine, College of Medicine, Chang-Gung University, Taoyuan 33302, Taiwan
| | - Ju-Bei Yen
- Graduate Institute of Clinical Medical Sciences, Chang-Gung University, Taoyuan 33302, Taiwan; Department of Pediatrics, Chang-Gung Memorial Hospital, Chiayi 61363, Taiwan
| | - Ann-Chi Liu
- Department of Respiratory Care, Chang-Gung University of Science and Technology, Chiayi 61363, Taiwan
| | - Ya-Hui Hung
- Department of Respiratory Care, Chang-Gung University of Science and Technology, Chiayi 61363, Taiwan
| | - Pey-Jium Chang
- Graduate Institute of Clinical Medical Sciences, Chang-Gung University, Taoyuan 33302, Taiwan; Department of Nephrology, Chang-Gung Memorial Hospital, Chiayi 61363, Taiwan.
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Lan YY, Chang FH, Tsai JH, Chang Y. Epstein-Barr virus Rta promotes invasion of bystander tumor cells through paracrine of matrix metalloproteinase 9. Biochem Biophys Res Commun 2018; 503:2160-2166. [PMID: 30082032 DOI: 10.1016/j.bbrc.2018.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 08/01/2018] [Indexed: 10/28/2022]
Abstract
Clinical studies suggest a positive association between malignant progression of nasopharyngeal carcinoma (NPC) and Rta, a transcription factor of Epstein-Barr virus (EBV). However, Rta induces cellular senescence in vitro. To provide an underlying mechanism integrating these clues, we adapted a concept of senescence-associated secretory phenotype (SASP), based on which senescent cells facilitate tumor progression through paracrine. First, Rta-expressing NPC cells themselves show reduced invasiveness but promote invasion of Rta-negative tumor cells through secreted factors. Secretion of matrix metalloproteinase 9 (MMP9), an SASP protein, is increased by Rta, which requires the C-terminus of Rta and Rta-induced activation of E2F. Furthermore, the Rta-induced, paracrine-mediated pro-invasive effect is blocked upon knockdown of MMP9 expression or treatment with an MMP9 inhibitor. This study not only indicates that Rta can contribute to NPC progression through paracrine but also supports that MMP9 is a potential therapeutic target to prevent NPC metastasis.
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Affiliation(s)
- Yu-Yan Lan
- Department of Physical Therapy, Shu-Zen Junior College of Medicine and Management, Kaohsiung, 821, Taiwan; National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, 704, Taiwan
| | - Fang-Hsin Chang
- Department of Microbiology and Immunology, Medical College, National Cheng Kung University, Tainan, 701, Taiwan; National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, 704, Taiwan
| | - Jen-Hao Tsai
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, 704, Taiwan
| | - Yao Chang
- Department of Microbiology and Immunology, Medical College, National Cheng Kung University, Tainan, 701, Taiwan; National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, 704, Taiwan.
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DeCotiis JL, Lukac DM. KSHV and the Role of Notch Receptor Dysregulation in Disease Progression. Pathogens 2017; 6:E34. [PMID: 28777778 DOI: 10.3390/pathogens6030034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/17/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of two human cancers, Kaposi's Sarcoma (KS) and primary effusion lymphoma (PEL), and a lymphoproliferation, Multicentric Castleman's Disease (MCD). Progression to tumor development in KS is dependent upon the reactivation of the virus from its latent state. We, and others, have shown that the Replication and transcriptional activator (Rta) protein is the only viral gene product that is necessary and sufficient for viral reactivation. To induce the reactivation and transcription of viral genes, Rta forms a complex with the cellular DNA binding component of the canonical Notch signaling pathway, recombination signal binding protein for Jk (RBP-Jk). Formation of this Rta:RBP-Jk complex is necessary for viral reactivation to occur. Expression of activated Notch has been shown to be dysregulated in KSHV infected cells and to be necessary for cell growth and disease progression. Studies into the involvement of activated Notch in viral reactivation have yielded varied results. In this paper, we review the current literature regarding Notch dysregulation by KSHV and its role in viral infection and cellular pathogenesis.
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Abstract
The life cycle of Kaposi’s sarcoma-associated herpesvirus (KSHV) consists of two phases, latent and lytic. The virus establishes latency as a strategy for avoiding host immune surveillance and fusing symbiotically with the host for lifetime persistent infection. However, latency can be disrupted and KSHV is reactivated for entry into the lytic replication. Viral lytic replication is crucial for efficient dissemination from its long-term reservoir to the sites of disease and for the spread of the virus to new hosts. The balance of these two phases in the KSHV life cycle is important for both the virus and the host and control of the switch between these two phases is extremely complex. Various environmental factors such as oxidative stress, hypoxia, and certain chemicals have been shown to switch KSHV from latency to lytic reactivation. Immunosuppression, unbalanced inflammatory cytokines, and other viral co-infections also lead to the reactivation of KSHV. This review article summarizes the current understanding of the initiation and regulation of KSHV reactivation and the mechanisms underlying the process of viral lytic replication. In particular, the central role of an immediate-early gene product RTA in KSHV reactivation has been extensively investigated. These studies revealed multiple layers of regulation in activation of RTA as well as the multifunctional roles of RTA in the lytic replication cascade. Epigenetic regulation is known as a critical layer of control for the switch of KSHV between latency and lytic replication. The viral non-coding RNA, PAN, was demonstrated to play a central role in the epigenetic regulation by serving as a guide RNA that brought chromatin remodeling enzymes to the promoters of RTA and other lytic genes. In addition, a novel dimension of regulation by microPeptides emerged and has been shown to regulate RTA expression at the protein level. Overall, extensive investigation of KSHV reactivation and lytic replication has revealed a sophisticated regulation network that controls the important events in KSHV life cycle.
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Affiliation(s)
- Kawalpreet K Aneja
- Department of Microbiology, University of Pennsylvania School of Dental Medicine, PhiladelphiaPA, USA
| | - Yan Yuan
- Department of Microbiology, University of Pennsylvania School of Dental Medicine, PhiladelphiaPA, 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Hussain K, Abu-Khumra SKA, Alnajjar FJK, Abdo MM. Triple trouble: A case of traumatic cervical spinal cord injury in a patient with ossification of posterior longitudinal ligament and disc prolapse. Turk J Emerg Med 2016; 16:129-131. [PMID: 27857994 PMCID: PMC5103061 DOI: 10.1016/j.tjem.2015.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 02/02/2015] [Accepted: 02/11/2015] [Indexed: 11/23/2022] Open
Abstract
We describe the case of a trauma patient who presented to our emergency department with signs and symptoms suggestive of cervical cord injury. The patient had an underlying ossification of the posterior longitudinal ligament with multiple cervical disc prolapses from C3 to C7. The presence of these two factors increased the impact of the traumatic cervical cord injury. The patient underwent spinal decompression via laminectomy. Unfortunately, his neurological status did not show any significant improvement after the surgery. Our aim is to highlight the association between ossification of the posterior longitudinal ligament and spinal cord injury in trauma patients.
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Affiliation(s)
- Kosar Hussain
- Department of Internal Medicine, Rashid Hospital, Dubai Health Authority, Dubai, United Arab Emirates
| | - Sally Khalid Ahmed Abu-Khumra
- Department of Emergency Medicine, Rashid Hospital Trauma Center, Dubai Health Authority, Dubai, United Arab Emirates
| | - Firas Jaafar Kareem Alnajjar
- Department of Emergency Medicine, Rashid Hospital Trauma Center, Dubai Health Authority, Dubai, United Arab Emirates
| | - Motea Mohamad Abdo
- Department of Emergency Medicine, Rashid Hospital Trauma Center, Dubai Health Authority, Dubai, United Arab Emirates
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Li H, Liu S, Hu J, Luo X, Li N, M Bode A, Cao Y. Epstein-Barr virus lytic reactivation regulation and its pathogenic role in carcinogenesis. Int J Biol Sci 2016; 12:1309-1318. [PMID: 27877083 PMCID: PMC5118777 DOI: 10.7150/ijbs.16564] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/20/2016] [Indexed: 12/27/2022] Open
Abstract
Epstein-Barr virus (EBV) has been associated with several types of human cancers. In the host, EBV can establish two alternative modes of life cycle, known as latent or lytic and the switch from latency to the lytic cycle is known as EBV reactivation. Although EBV in cancer cells is found mostly in latency, a small number of lytically-infected cells promote carcinogenesis through the release of growth factors and oncogenic cytokines. This review focuses on the mechanisms by which EBV reactivation is controlled by cellular and viral factors, and discusses how EBV lytic infection contributes to human malignancies.
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Affiliation(s)
- Hongde Li
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha 410078, China; Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha 410078, China; Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha 410078, China
| | - Sufang Liu
- Division of Hematology, Institute of Molecular Hematology, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Jianmin Hu
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha 410078, China; Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha 410078, China; Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha 410078, China
| | - Xiangjian Luo
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha 410078, China; Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha 410078, China; Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha 410078, China
| | - Namei Li
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha 410078, China; Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha 410078, China; Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha 410078, China
| | - Ann M Bode
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Ya Cao
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha 410078, China; Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha 410078, China; Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha 410078, China
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DeMaster LK, Rose TM. A critical Sp1 element in the rhesus rhadinovirus (RRV) Rta promoter confers high-level activity that correlates with cellular permissivity for viral replication. Virology 2013; 448:196-209. [PMID: 24314650 DOI: 10.1016/j.virol.2013.10.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 08/25/2013] [Accepted: 10/08/2013] [Indexed: 10/26/2022]
Abstract
KSHV establishes characteristic latent infections in vitro, while RRV, a related macaque rhadinovirus, establishes characteristic permissive infections with virus replication. We identified cells that are not permissive for RRV replication and recapitulate the latent KSHV infection and reactivation processes. The RRV replication and transactivator (Rta) promoter was characterized in permissive and non-permissive cells and compared to the KSHV Rta promoter. Both promoters contained a critical Sp1 element, had equivalent activities in different cell types, and were inhibited by LANA. RRV and KSHV infections were non-permissive in cells with low Rta promoter activity. While RRV infections were permissive in cells with high basal promoter activity, KSHV infections remained non-permissive. Our studies suggest that RRV lacks the Rta-inducible LANA promoter that is responsible for LANA inhibition of the KSHV Rta promoter and induction of latency during KSHV infection. Instead, the outcome of RRV infection is determined by host factors, such as Sp1.
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Affiliation(s)
- Laura K DeMaster
- Department of Global Health, University of Washington, Seattle, WA 98195, USA; Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, WA 98101, USA.
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Abstract
Epstein-Barr virus (EBV) encodes a transcription factor, Rta, which is required to activate the transcription of EBV lytic genes. This study demonstrates that treating P3HR1 cells with a proteasome inhibitor, MG132, causes the accumulation of SUMO-Rta and promotes the expression of EA-D. GST pulldown and coimmunoprecipitation studies reveal that RNF4, a RING-domain-containing ubiquitin E3 ligase, interacts with Rta. RNF4 also targets SUMO-2-conjugated Rta and promotes its ubiquitination in vitro. Additionally, SUMO interaction motifs in RNF4 are important to the ubiquitination of Rta because the RNF4 mutant with a mutation at the motifs eliminates ubiquitination. The mutation of four lysine residues on Rta that abrogated SUMO-3 conjugation to Rta also decreases the enhancement of the ubiquitination of Rta by RNF4. This finding demonstrates that RNF4 is a SUMO-targeted ubiquitin E3 ligase of Rta. Finally, knockdown of RNF4 enhances the expression of Rta and EA-D, subsequently promoting EBV lytic replication and virions production. Results of this study significantly contribute to efforts to elucidate a SUMO-targeted ubiquitin E3 ligase that regulates Rta ubiquitination to influence the lytic development of EBV.
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Affiliation(s)
- Ya-Chun Yang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan
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Abstract
Viruses are obligate intracellular pathogens whose biological success depends upon replication and packaging of viral genomes, and transmission of progeny viruses to new hosts. The biological success of herpesviruses is enhanced by their ability to reproduce their genomes without producing progeny viruses or killing the host cells, a process called latency. Latency permits a herpesvirus to remain undetected in its animal host for decades while maintaining the potential to reactivate, or switch, to a productive life cycle when host conditions are conducive to generating viral progeny. Direct interactions between many host and viral molecules are implicated in controlling herpesviral reactivation, suggesting complex biological networks that control the decision. One viral protein that is necessary and sufficient to switch latent Kaposi’s sarcoma-associated herpesvirus (KSHV) into the lytic infection cycle is called K-Rta. K-Rta is a transcriptional activator that specifies promoters by binding DNA directly and interacting with cellular proteins. Among these cellular proteins, binding of K-Rta to RBP-Jk is essential for viral reactivation. In contrast to the canonical model for Notch signaling, RBP-Jk is not uniformly and constitutively bound to the latent KSHV genome, but rather is recruited to DNA by interactions with K-Rta. Stimulation of RBP-Jk DNA binding requires high affinity binding of Rta to repetitive and palindromic “CANT DNA repeats” in promoters, and formation of ternary complexes with RBP-Jk. However, while K-Rta expression is necessary for initiating KSHV reactivation, K-Rta’s role as the switch is inefficient. Many factors modulate K-Rta’s function, suggesting that KSHV reactivation can be significantly regulated post-Rta expression and challenging the notion that herpesviral reactivation is bistable. This review analyzes rapidly evolving research on KSHV K-Rta to consider the role of K-Rta promoter specification in regulating the progression of KSHV reactivation.
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Affiliation(s)
- Jonathan Guito
- Graduate School of Biomedical Sciences, New Jersey Medical School, University of Medicine and Dentistry of New Jersey Newark, NJ, USA
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