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Luo R, Zhuo Y, Du Q, Xiao R. POU2F2 promotes the proliferation and motility of lung cancer cells by activating AGO1. BMC Pulm Med 2021; 21:117. [PMID: 33832481 PMCID: PMC8034198 DOI: 10.1186/s12890-021-01476-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 03/23/2021] [Indexed: 01/11/2023] Open
Abstract
Background To detect and investigate the expression of POU domain class 2 transcription factor 2 (POU2F2) in human lung cancer tissues, its role in lung cancer progression, and the potential mechanisms. Methods Immunohistochemical (IHC) assays were conducted to assess the expression of POU2F2 in human lung cancer tissues. Immunoblot assays were performed to assess the expression levels of POU2F2 in human lung cancer tissues and cell lines. CCK-8, colony formation, and transwell-migration/invasion assays were conducted to detect the effects of POU2F2 and AGO1 on the proliferaion and motility of A549 and H1299 cells in vitro. CHIP and luciferase assays were performed for the mechanism study. A tumor xenotransplantation model was used to detect the effects of POU2F2 on tumor growth in vivo. Results We found POU2F2 was highly expressed in human lung cancer tissues and cell lines, and associated with the lung cancer patients’ prognosis and clinical features. POU2F2 promoted the proliferation, and motility of lung cancer cells via targeting AGO1 in vitro. Additionally, POU2F2 promoted tumor growth of lung cancer cells via AGO1 in vivo. Conclusion We found POU2F2 was highly expressed in lung cancer cells and confirmed the involvement of POU2F2 in lung cancer progression, and thought POU2F2 could act as a potential therapeutic target for lung cancer. Supplementary Information The online version contains supplementary material available at 10.1186/s12890-021-01476-9.
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Affiliation(s)
- Ronggang Luo
- Department of Thoracic Surgery, The First Affiliated Hospital of Fujian Medical University, No.20 Chazhong Road, Fuzhou City, 350005, Fujian Province, China
| | - Yi Zhuo
- Department of Thoracic Surgery, The First Affiliated Hospital of Fujian Medical University, No.20 Chazhong Road, Fuzhou City, 350005, Fujian Province, China.
| | - Quan Du
- Department of Thoracic Surgery, The First Affiliated Hospital of Fujian Medical University, No.20 Chazhong Road, Fuzhou City, 350005, Fujian Province, China
| | - Rendong Xiao
- Department of Thoracic Surgery, The First Affiliated Hospital of Fujian Medical University, No.20 Chazhong Road, Fuzhou City, 350005, Fujian Province, China
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2
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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] [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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Sanchez-Martin D, Uldrick TS, Kwak H, Ohnuki H, Polizzotto MN, Annunziata CM, Raffeld M, Wyvill KM, Aleman K, Wang V, Marshall VA, Whitby D, Yarchoan R, Tosato G. Evidence for a Mesothelial Origin of Body Cavity Effusion Lymphomas. J Natl Cancer Inst 2017; 109:3078996. [PMID: 28376153 DOI: 10.1093/jnci/djx016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/20/2017] [Indexed: 12/19/2022] Open
Abstract
Background Primary effusion lymphoma (PEL) is a Kaposi's sarcoma herpes virus (KSHV)-induced lymphoma that typically arises in body cavities of HIV-infected patients. PEL cells are often co-infected with Epstein-Barr virus (EBV). "PEL-like" lymphoma is a KSHV-unrelated lymphoma that arises in body cavities of HIV-negative patients. "PEL-like" lymphoma is sometimes EBV positive. The derivation of PEL/"PEL-like" cells is unclear. Methods Mesothelial cells were cultured from body cavity effusions of 23 patients. Cell proliferation, cytokine secretion, marker phenotypes, KSHV/EBV infection, and clonality were evaluated by standard methods. Gene expression was measured by quantitative polymerase chain reaction and immunoblotting. A mouse model of PEL (3 mice/group) was used to evaluate tumorigenicity. Results We found that the mesothelia derived from six effusions of HIV-infected patients with PEL or other KSHV-associated diseases contained rare KSHV + or EBV + mesothelial cells. After extended culture (16-17 weeks), some mesothelial cells underwent a trans-differentiation process, generating lymphoid-type CD45 + /B220 + , CD5 + , CD27 + , CD43 + , CD11c + , and CD3 - cells resembling "B1-cells," most commonly found in mouse body cavities. These "B1-like" cells were short lived. However, long-term KSHV + EBV - and EBV + KSHV - clonal cell lines emerged from mesothelial cultures from two patients that were clonally distinct from the monoclonal or polyclonal B-cell populations found in the patients' original effusions. Conclusions Mesothelial-to-lymphoid transformation is a newly identified in vitro process that generates "B1-like" cells and is associated with the emergence of long-lived KSHV or EBV-infected cell lines in KSHV-infected patients. These results identify mesothelial cultures as a source of PEL cells and lymphoid cells in humans.
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Affiliation(s)
- David Sanchez-Martin
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, USA
| | - Thomas S Uldrick
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
| | - Hyeongil Kwak
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, USA
| | - Hidetaka Ohnuki
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, USA
| | - Mark N Polizzotto
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
| | - Christina M Annunziata
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Mark Raffeld
- Laboratory of Pathology, National Cancer Institute, Bethesda, MD, USA
| | - Kathleen M Wyvill
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
| | - Karen Aleman
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
| | - Victoria Wang
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
| | - Vickie A Marshall
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Denise Whitby
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Robert Yarchoan
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
| | - Giovanna Tosato
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, USA
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Aneja KK, Yuan Y. Reactivation and Lytic Replication of Kaposi's Sarcoma-Associated Herpesvirus: An Update. Front Microbiol 2017; 8:613. [PMID: 28473805 PMCID: PMC5397509 DOI: 10.3389/fmicb.2017.00613] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/27/2017] [Indexed: 12/30/2022] Open
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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Wu W, Youm W, Rezk SA, Zhao X. Human herpesvirus 8-unrelated primary effusion lymphoma-like lymphoma: report of a rare case and review of 54 cases in the literature. Am J Clin Pathol 2013; 140:258-73. [PMID: 23897264 DOI: 10.1309/ajcphz3cho4huwet] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVES To report a patient with primary effusion lymphoma who was negative for human herpesvirus-8 (HHV-8), human immunodeficiency virus, Epstein-Barr virus, hepatitis C virus, and hepatitis B virus, as well as review 54 reported cases of HHV-8-unrelated primary effusion lymphoma (PEL)-like lymphoma in the literature to clarify the nature of this entity. METHODS The patients' characteristics, clinical presentation, pathogenesis, morphologic-immunophenotypic features, clinical management, and prognosis were studied. RESULTS HHV-8-negative PEL-like lymphomas often occur in immunocompetent and elderly patients, are sometimes associated with chronic inflammation-related fluid overload, are mostly large B-cell or large B-cell with plasmacytic differentiation type, and are associated with a better prognosis. CONCLUSIONS In various aspects, HHV-8-unrelated PEL-like lymphoma is a different entity from HHV-8-related PEL. Immunophenotype, morphology, and c-myc/8q24 status should be included for differential diagnosis. A test for c-myc or 8q24 abnormalities should be recommended for subdividing HHV-8-unrelated PEL-like lymphoma, which may have benefits in patient management.
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Affiliation(s)
- William Wu
- Department of Pathology and Laboratory Medicine, University of California, Irvine
| | - Wonita Youm
- Department of Pathology and Laboratory Medicine, University of California, Irvine
| | - Sherif A. Rezk
- Department of Pathology and Laboratory Medicine, University of California, Irvine
| | - Xiaohui Zhao
- Department of Pathology and Laboratory Medicine, University of California, Irvine
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6
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Guito J, Lukac DM. KSHV Rta Promoter Specification and Viral Reactivation. Front Microbiol 2012; 3:30. [PMID: 22347875 PMCID: PMC3278982 DOI: 10.3389/fmicb.2012.00030] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 01/18/2012] [Indexed: 11/27/2022] Open
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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Robinson AR, Kwek SS, Kenney SC. The B-cell specific transcription factor, Oct-2, promotes Epstein-Barr virus latency by inhibiting the viral immediate-early protein, BZLF1. PLoS Pathog 2012; 8:e1002516. [PMID: 22346751 PMCID: PMC3276558 DOI: 10.1371/journal.ppat.1002516] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 12/16/2011] [Indexed: 01/16/2023] Open
Abstract
The Epstein-Barr virus (EBV) latent-lytic switch is mediated by the BZLF1 immediate-early protein. EBV is normally latent in memory B cells, but cellular factors which promote viral latency specifically in B cells have not been identified. In this report, we demonstrate that the B-cell specific transcription factor, Oct-2, inhibits the function of the viral immediate-early protein, BZLF1, and prevents lytic viral reactivation. Co-transfected Oct-2 reduces the ability of BZLF1 to activate lytic gene expression in two different latently infected nasopharyngeal carcinoma cell lines. Furthermore, Oct-2 inhibits BZLF1 activation of lytic EBV promoters in reporter gene assays, and attenuates BZLF1 binding to lytic viral promoters in vivo. Oct-2 interacts directly with BZLF1, and this interaction requires the DNA-binding/dimerization domain of BZLF1 and the POU domain of Oct-2. An Oct-2 mutant (Δ262–302) deficient for interaction with BZLF1 is unable to inhibit BZLF1-mediated lytic reactivation. However, an Oct-2 mutant defective for DNA-binding (Q221A) retains the ability to inhibit BZLF1 transcriptional effects and DNA-binding. Importantly, shRNA-mediated knockdown of endogenous Oct-2 expression in several EBV-positive Burkitt lymphoma and lymphoblastoid cell lines increases the level of lytic EBV gene expression, while decreasing EBNA1 expression. Moreover, treatments which induce EBV lytic reactivation, such as anti-IgG cross-linking and chemical inducers, also decrease the level of Oct-2 protein expression at the transcriptional level. We conclude that Oct-2 potentiates establishment of EBV latency in B cells. Epstein-Barr virus (EBV) is a human herpesvirus associated with B-cell malignancies. EBV infection of cells can result in either lytic replication or latency. Memory B cells are the primary site of EBV latency within the human host, while oropharyngeal epithelial cells support the lytic form of infection. However, the cellular mechanism(s) that enable EBV to establish viral latency in a B-cell specific manner are not currently understood. In this report, we show that the B-cell specific cellular transcription factor, Oct-2, promotes viral latency by inhibiting the lytic form of infection. We find that Oct-2 interacts directly with the EBV immediate-early protein, BZLF1, and abrogates its ability to activate lytic viral gene transcription through protein-protein interactions off the DNA. Furthermore, knockdown of endogenous Oct-2 expression in several latently-infected Burkitt lymphoma B-cell lines increases EBV lytic protein expression. In addition, we show that certain stimuli which can prompt lytic EBV reactivation in B cells also decrease expression of endogenous Oct-2. Our results suggest that the cellular transcription factor, Oct-2, promotes EBV latency in a B-cell dependent manner.
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Affiliation(s)
- Amanda R. Robinson
- Department of Oncology, McArdle Laboratory for Cancer Research , University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Department of Cellular and Molecular Biology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Swee Sen Kwek
- Department of Oncology, McArdle Laboratory for Cancer Research , University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Shannon C. Kenney
- Department of Oncology, McArdle Laboratory for Cancer Research , University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- * E-mail:
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Cellular transcription factor Oct-1 interacts with the Epstein-Barr virus BRLF1 protein to promote disruption of viral latency. J Virol 2011; 85:8940-53. [PMID: 21697476 DOI: 10.1128/jvi.00569-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The Epstein-Barr virus (EBV) latent-to-lytic switch is an essential part of the viral life cycle, but the cellular factors that promote viral reactivation are not well defined. In this report, we demonstrate that the cellular transcription factor Oct-1 cooperates with the EBV immediate-early protein BRLF1 (R, Rta) to induce lytic viral reactivation. We show that cotransfected Oct-1 enhances the ability of BRLF1 to activate lytic gene expression in 293 cells stably infected with a BRLF1-defective EBV mutant (BRLF1-stop) and that Oct-1 increases BRLF1-mediated activation of lytic EBV promoters in reporter gene assays. We find that Oct-1 interacts directly with BRLF1 in vitro and that a mutant BRLF1 protein (the M140A mutant) attenuated for the ability to interact with Oct-1 in vitro is also resistant to Oct-1-mediated transcriptional enhancement in 293 BRLF1-stop cells. Furthermore, we show that cotransfected Oct-1 augments BRLF1 binding to a variety of lytic EBV promoters in chromatin immunoprecipitation (ChIP) assays (including the BZLF1, BMRF1, and SM promoters) and that BRLF1 tethers Oct-1 to lytic EBV promoters. In addition, we demonstrate that an Oct-1 mutant defective in DNA binding (the S335D mutant) still retains the ability to enhance BRLF1 transcriptional effects. Finally, we show that knockdown of endogenous Oct-1 expression reduces the level of constitutive lytic EBV gene expression in both EBV-positive B-cell and EBV-positive epithelial cell lines. These results suggest that Oct-1 acts as a positive regulator of EBV lytic gene expression and that this effect is at least partially mediated through its interaction with the viral protein BRLF1.
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Oxidative stress induces reactivation of Kaposi's sarcoma-associated herpesvirus and death of primary effusion lymphoma cells. J Virol 2010; 85:715-24. [PMID: 21068240 DOI: 10.1128/jvi.01742-10] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL) cells are predominantly infected with latent Kaposi's sarcoma-associated herpesvirus (KSHV), presenting a barrier to the destruction of tumor cells. Latent KSHV can be reactivated to undergo lytic replication. Here we report that in PEL cells, oxidative stress induced by upregulated reactive oxygen species (ROS) can lead to KSHV reactivation or cell death. ROS are upregulated by NF-κB inhibition and are required for subsequent KSHV reactivation. Disruption of the intracellular redox balance through depletion of the antioxidant glutathione or inhibition of the antioxidant enzyme catalase also induces KSHV reactivation, suggesting that hydrogen peroxide induces reactivation. In addition, p38 signaling is required for KSHV reactivation induced by ROS. Furthermore, treatment of PEL cells with a higher concentration of the NF-κB inhibitor than that used for inducing KSHV reactivation further upregulates ROS and induces massive cell death. ROS, but not p38 signaling, are required for PEL cell death induced by NF-κB inhibition as well as by glutathione depletion. Importantly, anticancer drugs, such as cisplatin and arsenic trioxide, also induce KSHV reactivation and PEL cell death in a ROS-dependent manner. Our study thus establishes a critical role for ROS and oxidative stress in the regulation of KSHV reactivation and PEL cell death. Disrupting the cellular redox balance may be a potential strategy for treating KSHV-associated lymphoma.
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De Filippi R, Iaccarino G, Frigeri F, Di Francia R, Crisci S, Capobianco G, Arcamone M, Becchimanzi C, Amoroso B, De Chiara A, Corazzelli G, Pinto A. Elevation of clonal serum free light chains in patients with HIV-negative primary effusion lymphoma (PEL) and PEL-like lymphoma. Br J Haematol 2009; 147:405-8. [PMID: 19681885 DOI: 10.1111/j.1365-2141.2009.07846.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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