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SoRelle ED, Reinoso-Vizcaino NM, Dai J, Barry AP, Chan C, Luftig MA. Epstein-Barr virus evades restrictive host chromatin closure by subverting B cell activation and germinal center regulatory loci. Cell Rep 2023; 42:112958. [PMID: 37561629 PMCID: PMC10559315 DOI: 10.1016/j.celrep.2023.112958] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/02/2023] [Accepted: 07/25/2023] [Indexed: 08/12/2023] Open
Abstract
Chromatin accessibility fundamentally governs gene expression and biological response programs that can be manipulated by pathogens. Here we capture dynamic chromatin landscapes of individual B cells during Epstein-Barr virus (EBV) infection. EBV+ cells that exhibit arrest via antiviral sensing and proliferation-linked DNA damage experience global accessibility reduction. Proliferative EBV+ cells develop expression-linked architectures and motif accessibility profiles resembling in vivo germinal center (GC) phenotypes. Remarkably, EBV elicits dark zone (DZ), light zone (LZ), and post-GC B cell chromatin features despite BCL6 downregulation. Integration of single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq), single-cell RNA sequencing (scRNA-seq), and chromatin immunoprecipitation sequencing (ChIP-seq) data enables genome-wide cis-regulatory predictions implicating EBV nuclear antigens (EBNAs) in phenotype-specific control of GC B cell activation, survival, and immune evasion. Knockouts validate bioinformatically identified regulators (MEF2C and NFE2L2) of EBV-induced GC phenotypes and EBNA-associated loci that regulate gene expression (CD274/PD-L1). These data and methods can inform high-resolution investigations of EBV-host interactions, B cell fates, and virus-mediated lymphomagenesis.
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Affiliation(s)
- Elliott D SoRelle
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA; Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC 27710, USA.
| | - Nicolás M Reinoso-Vizcaino
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Joanne Dai
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ashley P Barry
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Cliburn Chan
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Micah A Luftig
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA.
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SoRelle ED, Dai J, Reinoso-Vizcaino NM, Barry AP, Chan C, Luftig MA. Time-resolved transcriptomes reveal diverse B cell fate trajectories in the early response to Epstein-Barr virus infection. Cell Rep 2022; 40:111286. [PMID: 36044865 PMCID: PMC9879279 DOI: 10.1016/j.celrep.2022.111286] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 06/07/2022] [Accepted: 08/08/2022] [Indexed: 01/28/2023] Open
Abstract
Epstein-Barr virus infection of B lymphocytes elicits diverse host responses via well-adapted transcriptional control dynamics. Consequently, this host-pathogen interaction provides a powerful system to explore fundamental processes leading to consensus fate decisions. Here, we use single-cell transcriptomics to construct a genome-wide multistate model of B cell fates upon EBV infection. Additional single-cell data from human tonsils reveal correspondence of model states to analogous in vivo phenotypes within secondary lymphoid tissue, including an EBV+ analog of multipotent activated precursors that can yield early memory B cells. These resources yield exquisitely detailed perspectives of the transforming cellular landscape during an oncogenic viral infection that simulates antigen-induced B cell activation and differentiation. Thus, they support investigations of state-specific EBV-host dynamics, effector B cell fates, and lymphomagenesis. To demonstrate this potential, we identify EBV infection dynamics in FCRL4+/TBX21+ atypical memory B cells that are pathogenically associated with numerous immune disorders.
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Affiliation(s)
- Elliott D SoRelle
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA; Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC 27710, USA.
| | - Joanne Dai
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Nicolás M Reinoso-Vizcaino
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ashley P Barry
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Cliburn Chan
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Micah A Luftig
- Department of Molecular Genetics and Microbiology, Duke Center for Virology, Duke University School of Medicine, Durham, NC 27710, USA.
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Siegmund D, Wagner J, Wajant H. TNF Receptor Associated Factor 2 (TRAF2) Signaling in Cancer. Cancers (Basel) 2022; 14:cancers14164055. [PMID: 36011046 PMCID: PMC9406534 DOI: 10.3390/cancers14164055] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/05/2022] [Accepted: 08/19/2022] [Indexed: 12/19/2022] Open
Abstract
Simple Summary Tumor necrosis factor (TNF) receptor associated factor-2 (TRAF2) is an intracellular adapter protein with E3 ligase activity, which interacts with a plethora of other signaling proteins, including plasma membrane receptors, kinases, phosphatases, other E3 ligases, and deubiquitinases. TRAF2 is involved in various cancer-relevant cellular processes, such as the activation of transcription factors of the NFκB family, stimulation of mitogen-activated protein (MAP) kinase cascades, endoplasmic reticulum (ER) stress signaling, autophagy, and the control of cell death programs. In a context-dependent manner, TRAF2 promotes tumor development but it can also act as a tumor suppressor. Based on a general description, how TRAF2 in concert with TRAF2-interacting proteins and other TRAF proteins act at the molecular level is discussed for its importance for tumor development and its potential usefulness as a therapeutic target in cancer therapy. Abstract Tumor necrosis factor (TNF) receptor associated factor-2 (TRAF2) has been originally identified as a protein interacting with TNF receptor 2 (TNFR2) but also binds to several other receptors of the TNF receptor superfamily (TNFRSF). TRAF2, often in concert with other members of the TRAF protein family, is involved in the activation of the classical NFκB pathway and the stimulation of various mitogen-activated protein (MAP) kinase cascades by TNFRSF receptors (TNFRs), but is also required to inhibit the alternative NFκB pathway. TRAF2 has also been implicated in endoplasmic reticulum (ER) stress signaling, the regulation of autophagy, and the control of cell death programs. TRAF2 fulfills its functions by acting as a scaffold, bringing together the E3 ligase cellular inhibitor of apoptosis-1 (cIAP1) and cIAP2 with their substrates and various regulatory proteins, e.g., deubiquitinases. Furthermore, TRAF2 can act as an E3 ligase by help of its N-terminal really interesting new gene (RING) domain. The finding that TRAF2 (but also several other members of the TRAF family) interacts with the latent membrane protein 1 (LMP1) oncogene of the Epstein–Barr virus (EBV) indicated early on that TRAF2 could play a role in the oncogenesis of B-cell malignancies and EBV-associated non-keratinizing nasopharyngeal carcinoma (NPC). TRAF2 can also act as an oncogene in solid tumors, e.g., in colon cancer by promoting Wnt/β-catenin signaling. Moreover, tumor cell-expressed TRAF2 has been identified as a major factor-limiting cancer cell killing by cytotoxic T-cells after immune checkpoint blockade. However, TRAF2 can also be context-dependent as a tumor suppressor, presumably by virtue of its inhibitory effect on the alternative NFκB pathway. For example, inactivating mutations of TRAF2 have been associated with tumor development, e.g., in multiple myeloma and mantle cell lymphoma. In this review, we summarize the various TRAF2-related signaling pathways and their relevance for the oncogenic and tumor suppressive activities of TRAF2. Particularly, we discuss currently emerging concepts to target TRAF2 for therapeutic purposes.
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Nascent Transcriptomics Reveal Cellular Prolytic Factors Upregulated Upstream of the Latent-to-Lytic Switch Protein of Epstein-Barr Virus. J Virol 2020; 94:JVI.01966-19. [PMID: 31941784 DOI: 10.1128/jvi.01966-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/08/2020] [Indexed: 12/15/2022] Open
Abstract
Lytic activation from latency is a key transition point in the life cycle of herpesviruses. Epstein-Barr virus (EBV) is a human herpesvirus that can cause lymphomas, epithelial cancers, and other diseases, most of which require the lytic cycle. While the lytic cycle of EBV can be triggered by chemicals and immunologic ligands, the lytic cascade is activated only when expression of the EBV latent-to-lytic switch protein ZEBRA is turned on. ZEBRA then transcriptionally activates other EBV genes and, together with some of those gene products, ensures completion of the lytic cycle. However, not every latently infected cell exposed to a lytic trigger turns on the expression of ZEBRA, resulting in responsive and refractory subpopulations. What governs this dichotomy? By examining the nascent transcriptome following exposure to a lytic trigger, we find that several cellular genes are transcriptionally upregulated temporally upstream of ZEBRA. These genes regulate lytic susceptibility to various degrees in latently infected cells that respond to mechanistically distinct lytic triggers. While increased expression of these cellular genes defines a prolytic state, such upregulation also runs counter to the well-known mechanism of viral-nuclease-mediated host shutoff that is activated downstream of ZEBRA. Furthermore, a subset of upregulated cellular genes is transcriptionally repressed temporally downstream of ZEBRA, indicating an additional mode of virus-mediated host shutoff through transcriptional repression. Thus, increased transcription of a set of host genes contributes to a prolytic state that allows a subpopulation of cells to support the EBV lytic cycle.IMPORTANCE Transition from latency to the lytic phase is necessary for herpesvirus-mediated pathology as well as viral spread and persistence in the population at large. Yet, viral genomes in only some cells in a population of latently infected cells respond to lytic triggers, resulting in subpopulations of responsive/lytic and refractory cells. Our investigations into this partially permissive phenotype of the herpesvirus Epstein-Barr virus (EBV) indicate that upon exposure to lytic triggers, certain cellular genes are transcriptionally upregulated, while viral latency genes are downregulated ahead of expression of the viral latent-to-lytic switch protein. These cellular genes contribute to lytic susceptibility to various degrees. Apart from indicating that there may be a cellular "prolytic" state, our findings indicate that (i) early transcriptional upregulation of cellular genes counters the well-known viral-nuclease-mediated host shutoff and (ii) subsequent transcriptional downregulation of a subset of early upregulated cellular genes is a previously undescribed mode of host shutoff.
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Cheerathodi MR, Meckes DG. The Epstein-Barr virus LMP1 interactome: biological implications and therapeutic targets. Future Virol 2018; 13:863-887. [PMID: 34079586 DOI: 10.2217/fvl-2018-0120] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The oncogenic potential of Epstein-Barr virus (EBV) is mostly attributed to latent membrane protein 1 (LMP1), which is essential and sufficient for transformation of fibroblast and primary lymphocytes. LMP1 expression results in the activation of multiple signaling cascades like NF-ΚB and MAP kinases that trigger cell survival and proliferative pathways. LMP1 specific signaling events are mediated through the recruitment of a number of interacting proteins to various signaling domains. Based on these properties, LMP1 is an attractive target to develop effective therapeutics to treat EBV-related malignancies. In this review, we focus on LMP1 interacting proteins, associated signaling events, and potential targets that could be exploited for therapeutic strategies.
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Affiliation(s)
- Mujeeb R Cheerathodi
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, 32306
| | - David G Meckes
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, 32306
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Global Proteomic Changes Induced by the Epstein-Barr Virus Oncoproteins Latent Membrane Protein 1 and 2A. mBio 2018; 9:mBio.00959-18. [PMID: 29921667 PMCID: PMC6016245 DOI: 10.1128/mbio.00959-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The Epstein-Barr virus (EBV) oncoproteins latent membrane protein 1 (LMP1) and LMP2A constitutively activate multiple signaling pathways, and both have been shown to interact with cellular ubiquitin ligases and affect cellular ubiquitination. To detect the LMP1- and LMP2A-mediated effects on the global cellular proteome, epithelial cell lines expressing LMP1 or LMP2A were analyzed using label-free quantitative proteomics. To identify proteins whose ubiquitination is affected by the viral proteins, the cells were cultured in the presence and absence of deubiquitinase (DUB) and proteasome inhibitors. More than 7,700 proteins were identified with high confidence and considerably more proteins showed significant differences in expression in the presence of inhibitors. Few of the differentially expressed proteins with or without inhibitors were common between LMP1 and LMP2A, confirming that the viral proteins induce unique changes in cell expression and function. However, ingenuity pathway analysis (IPA) of the data indicated that LMP1 and LMP2A modulate many of the same cellular regulatory pathways, including cell death and survival, cell movement, and actin filament dynamics. In addition, various proteasome subunits, ubiquitin-specific peptidases and conjugating enzymes, vesicle trafficking proteins, and NF-κB and mitogen-activated protein kinase signaling proteins were affected by LMP1 or LMP2A. These findings suggest that LMP1 and LMP2A may commonly target critical cell pathways through effects on distinct genes, with many cellular proteins modified by ubiquitination and/or degradation. The Epstein-Barr virus proteins latent membrane protein 1 and 2 have potent effects on cell growth and signaling. Both proteins bind to specific ubiquitin ligases and likely modulate the cellular proteome through ubiquitin-mediated effects on stability and intracellular location. In this study, a comprehensive proteomic analysis of the effects of LMP1 and LMP2A revealed that both proteins affected proteasome subunits, ubiquitin-specific conjugases and peptidases, and vesical trafficking proteins. The data suggest that the effects of these proteins on the abundance and ubiquitination of cellular proteins are in part responsible for their effects on cell growth regulation.
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7
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Liu X, Li Y, Peng S, Yu X, Li W, Shi F, Luo X, Tang M, Tan Z, Bode AM, Cao Y. Epstein-Barr virus encoded latent membrane protein 1 suppresses necroptosis through targeting RIPK1/3 ubiquitination. Cell Death Dis 2018; 9:53. [PMID: 29352166 PMCID: PMC5833833 DOI: 10.1038/s41419-017-0081-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 10/01/2017] [Accepted: 10/05/2017] [Indexed: 12/13/2022]
Abstract
Necroptosis is an alternative programmed cell death pathway that is unleashed in the absence of apoptosis and mediated by signaling complexes containing receptor-interating protein kinase 1 (RIPK1) and RIPK3. This form of cell death has recently been implicated in host defense system to eliminate pathogen-infected cells. However, only a few viral species such as herpes simplex virus (HSV) and cytomegalovirus (CMV) have evolved mechanisms inhibiting necroptosis to overcome host antiviral defense, which is important for successful pathogenesis. Here, we show that the γ-herpesvirus Epstein-Barr virus (EBV) blocks necroptosis in EBV-infected human nasopharyngeal epithelial cells and nasopharyngeal carcinoma cells. Our findings indicate that EBV-encoded latent membrane protein 1 (LMP1), which lacks an RIP homotypic interaction motif (RHIM) domain, has mechanisms distinct from RHIM signaling competition to inhibit this necroptotic pathway. Intriguingly, LMP1 interacts directly with both RIPK1 and RIPK3 through its C-terminal activation region. More importantly, LMP1 can modulate the post-translational modification of the two receptor-interacting proteins. We then show that LMP1-mediated promotion of K63-polyubiquitinated RIPK1, suppression of RIPK1 protein expression and inhibition of K63-polyubiquitinated RIPK3 induced a switch in cell fate from necroptotic death to survival. These findings provide direct evidence for the suppression of necroptosis by EBV and define a mechanism of LMP1 to interrupt the initiation process of necroptosis before necrosome formation.
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Affiliation(s)
- Xiaolan Liu
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - Yueshuo Li
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - Songling Peng
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - Xinfang Yu
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Wei Li
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Feng Shi
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - Xiangjian Luo
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - Min Tang
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - Zheqiong Tan
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China
| | - A M Bode
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Ya Cao
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan, China. .,Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan, China. .,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, Hunan, China.
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8
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Qian T, Chen F, Shi X, Li J, Li M, Chen Y, Hao F, Zhang D. Upregulation of the C/EBP β LAP isoform could be due to decreased TNFAIP3/TNIP1 expression in the peripheral blood mononuclear cells of patients with systemic lupus erythematosus. Mod Rheumatol 2016; 27:657-663. [PMID: 27659348 DOI: 10.1080/14397595.2016.1232331] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVES We aimed to examine CCAAT/enhancer-binding protein β (C/EBP β), TNF-alpha-induced protein 3 (TNFAIP3), and TNFAIP3-interacting protein 1 (TNIP1) expression in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients to assess their relationship in SLE pathogenesis. METHODS C/EBP β, TNIP1, and TNFAIP3 expression was assessed in PBMCs from 20 SLE patients and 20 controls by western blotting. The correlation between C/EBP β/TNFAIP3/TNIP1 expression and SLE disease activity was determined by Spearman's rank. C/EBP β, TNIP1, and TNFAIP3 levels in THP-1 cells, THP-1 cells transfected with plasmids encoding TNFAIP3 shRNA, and THP-1 cells infected with lentiviral vectors encoding TNIP1 shRNA were assessed by western blotting. RESULTS C/EBP β LAP isoform expression was increased and LIP/TNFAIP3/TNIP1 expression was decreased in SLE patients. LAP expression was positively correlated with SLE disease activity; TNFAIP3 and TNIP1 expression was negatively correlated with SLE disease activity. LAP expression was increased in SLE patients with proteinuria and elevated anti-dsDNA antibody, as well as in THP-1 cells transfected with plasmids encoding TNFAIP3 shRNA and THP-1 cells infected with lentiviral vectors encoding TNIP1 shRNA. CONCLUSIONS C/EBP β/TNFAIP3/TNIP1 is associated with SLE activity. The upregulated expression of C/EBP β LAP could be caused by reduced TNFAIP3/TNIP1 expression.
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Affiliation(s)
- Tian Qian
- a Department of Dermatology , Southwest Hospital, Third Military Medical University , Chongqing , P.R. China
| | - Fangru Chen
- b Department of Dermatology , Affiliated Hospital of Guilin Medical University , Guilin , P.R. China
| | - Xiaowei Shi
- c Department of Dermatology , General Hospital of Shenyang Military Area Command , Shenyang , P.R. China , and
| | - Jian Li
- a Department of Dermatology , Southwest Hospital, Third Military Medical University , Chongqing , P.R. China
| | - Min Li
- a Department of Dermatology , Southwest Hospital, Third Military Medical University , Chongqing , P.R. China
| | - Yan Chen
- d Department of Dermatology , Kunming General Hospital of Chengdu Military Region , Kunming , P.R. China
| | - Fei Hao
- a Department of Dermatology , Southwest Hospital, Third Military Medical University , Chongqing , P.R. China
| | - Dongmei Zhang
- a Department of Dermatology , Southwest Hospital, Third Military Medical University , Chongqing , P.R. China
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9
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Yin Q, Wang X, Roberts C, Flemington EK, Lasky JA. Methylation status and AP1 elements are involved in EBV-mediated miR-155 expression in EBV positive lymphoma cells. Virology 2016; 494:158-67. [PMID: 27110708 DOI: 10.1016/j.virol.2016.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/14/2016] [Accepted: 04/04/2016] [Indexed: 12/12/2022]
Abstract
The relationship between Epstein Barr Virus (EBV) and miR-155 is well established. EBV infection induces miR-155 expression, which is expressed at higher levels in EBV latency type III cells compared to EBV latency type I cells. However, the mechanism by which EBV latency genes activate miR-155 expression is still unclear. Here we present data showing that DNA methylation regulates miR-155 expression. We also provide evidence that the AP1 signaling pathway is involved in EBV-mediated miR-155 activation, and that Bay11 influences signaling of the miR-155 promoter AP1 element. Lastly, we show that LMP2A, LMP1 and EBNAs cannot activate miR-155 expression alone, indicating that the regulation of miR-155 by EBV is dependent on more than one EBV gene or cell signaling pathway. We conclude that the regulation of miR-155 in EBV-positive cells occurs through multiple cell signaling processes involving EBV-mediated chromatin remodeling, cell signaling regulation and transcription factor activation.
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Affiliation(s)
- Qinyan Yin
- Section of Pulmonary Diseases, Critical Care and Environmental Medicine, Department of Medicine, SL9, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
| | - Xia Wang
- Department of Pathology and Laboratory Medicine, SL79, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
| | - Claire Roberts
- Department of Pathology and Laboratory Medicine, SL79, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
| | - Erik K Flemington
- Department of Pathology and Laboratory Medicine, SL79, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
| | - Joseph A Lasky
- Section of Pulmonary Diseases, Critical Care and Environmental Medicine, Department of Medicine, SL9, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
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10
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Greenfeld H, Takasaki K, Walsh MJ, Ersing I, Bernhardt K, Ma Y, Fu B, Ashbaugh CW, Cabo J, Mollo SB, Zhou H, Li S, Gewurz BE. TRAF1 Coordinates Polyubiquitin Signaling to Enhance Epstein-Barr Virus LMP1-Mediated Growth and Survival Pathway Activation. PLoS Pathog 2015; 11:e1004890. [PMID: 25996949 PMCID: PMC4440769 DOI: 10.1371/journal.ppat.1004890] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 04/17/2015] [Indexed: 11/25/2022] Open
Abstract
The Epstein-Barr virus (EBV) encoded oncoprotein Latent Membrane Protein 1 (LMP1) signals through two C-terminal tail domains to drive cell growth, survival and transformation. The LMP1 membrane-proximal TES1/CTAR1 domain recruits TRAFs to activate MAP kinase, non-canonical and canonical NF-kB pathways, and is critical for EBV-mediated B-cell transformation. TRAF1 is amongst the most highly TES1-induced target genes and is abundantly expressed in EBV-associated lymphoproliferative disorders. We found that TRAF1 expression enhanced LMP1 TES1 domain-mediated activation of the p38, JNK, ERK and canonical NF-kB pathways, but not non-canonical NF-kB pathway activity. To gain insights into how TRAF1 amplifies LMP1 TES1 MAP kinase and canonical NF-kB pathways, we performed proteomic analysis of TRAF1 complexes immuno-purified from cells uninduced or induced for LMP1 TES1 signaling. Unexpectedly, we found that LMP1 TES1 domain signaling induced an association between TRAF1 and the linear ubiquitin chain assembly complex (LUBAC), and stimulated linear (M1)-linked polyubiquitin chain attachment to TRAF1 complexes. LMP1 or TRAF1 complexes isolated from EBV-transformed lymphoblastoid B cell lines (LCLs) were highly modified by M1-linked polyubiqutin chains. The M1-ubiquitin binding proteins IKK-gamma/NEMO, A20 and ABIN1 each associate with TRAF1 in cells that express LMP1. TRAF2, but not the cIAP1 or cIAP2 ubiquitin ligases, plays a key role in LUBAC recruitment and M1-chain attachment to TRAF1 complexes, implicating the TRAF1:TRAF2 heterotrimer in LMP1 TES1-dependent LUBAC activation. Depletion of either TRAF1, or the LUBAC ubiquitin E3 ligase subunit HOIP, markedly impaired LCL growth. Likewise, LMP1 or TRAF1 complexes purified from LCLs were decorated by lysine 63 (K63)-linked polyubiqutin chains. LMP1 TES1 signaling induced K63-polyubiquitin chain attachment to TRAF1 complexes, and TRAF2 was identified as K63-Ub chain target. Co-localization of M1- and K63-linked polyubiquitin chains on LMP1 complexes may facilitate downstream canonical NF-kB pathway activation. Our results highlight LUBAC as a novel potential therapeutic target in EBV-associated lymphoproliferative disorders. The linear ubiquitin assembly complex (LUBAC) plays crucial roles in immune receptor-mediated NF-kB and MAP kinase pathway activation. Comparatively little is known about the extent to which microbial pathogens use LUBAC to activate downstream pathways. We demonstrate that TRAF1 enhances EBV oncoprotein LMP1 TES1/CTAR1 domain mediated MAP kinase and canonical NF-kB activation. LMP1 TES1 signaling induces association between TRAF1 and LUBAC, and triggers M1-polyubiquitin chain attachment to TRAF1 complexes. TRAF1 and LMP1 complexes are decorated by M1-polyubiquitin chains in LCL extracts. TRAF2 plays a key role in LMP1-induced LUBAC recruitment and M1-chain attachment to TRAF1 complexes. TRAF1 and LMP1 complexes are modified by lysine 63-linked polyubiquitin chains in LCL extracts, and TRAF2 is a target of LMP1-induced K63-ubiquitin chain attachment. Thus, the TRAF1:TRAF2 heterotrimer may coordinate ubiquitin signaling downstream of TES1. Depletion of TRAF1 or the LUBAC subunit HOIP impairs LCL growth and survival. Thus, although TRAF1 is the only TRAF without a RING finger ubiquitin ligase domain, TRAF1 nonetheless has important roles in ubiqutin-mediated signal transduction downstream of LMP1. Our work suggests that LUBAC is important for EBV-driven B-cell proliferation, and suggests that LUBAC may be a novel therapeutic target in EBV-associated lymphoproliferative disorders.
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Affiliation(s)
- Hannah Greenfeld
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Kaoru Takasaki
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Michael J. Walsh
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Ina Ersing
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Katharina Bernhardt
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Yijie Ma
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Bishi Fu
- Division of Immunology, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Camille W. Ashbaugh
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Jackson Cabo
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Sarah B. Mollo
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Hufeng Zhou
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Shitao Li
- Division of Immunology, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Benjamin E. Gewurz
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- * E-mail:
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11
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Abstract
The Epstein-Barr virus protein latent membrane protein 1 (LMP1) has two NF-κB activating domains within its intracellular carboxy terminus (carboxy-terminal activating region 1 [CTAR1] and CTAR2). LMP1-CTAR1 is required for B-lymphocyte transformation, is capable of transforming rodent fibroblasts, and uniquely activates phosphoinositol (PI3) kinase, the noncanonical NF-κB pathway, and expression of the epidermal growth factor receptor (EGFR). In this study, the effects of LMP1-CTAR1 on cellular gene expression were determined by high-throughput sequencing. Additionally, the binding of bcl3 was determined using chromatin immunoprecipitation (ChIP) and sequencing. LMP1-CTAR1 induced few changes in transcription with more genes showing decreased expression. Ingenuity pathway analysis indicated significant enrichment for genes involved in cancer and cellular movement, survival, growth, and proliferation pathways. ChIP in combination with high-throughput sequencing (ChIP-Seq) identified bcl3 binding for more than 2,000 genes in LMP1-CTAR1-expressing cells with more than 90% of the peaks at genes detected within the probable promoter region. Only a small subset of the genes with significant changes in expression had corresponding peaks in the bcl3 ChIP. However, both NFKB2 and PI3 kinase were identified in the bcl3 ChIP. Additionally, many of the predicted upstream regulators for the changes in expression were identified in the bcl3 ChIP. Analysis of the proteins in the NF-κB pathway revealed many changes identified by the high-throughput RNA sequencing (RNA-Seq) and bcl3 ChIP that would likely activate noncanonical NF-κB signaling and possibly inhibit canonical NF-κB signaling. These findings suggest that the two LMP1 signaling domains modulate their combined activity and that the bcl3 transcription factor is likely responsible for some of the unique effects of CTAR1 on cellular expression. The Epstein-Barr virus protein latent membrane protein 1 (LMP1) has potent effects on cell growth. LMP1 has two regions, carboxy-terminal activating region 1 (CTAR1) and CTAR2, that distinctly activate NF-κB, a transcription factor complex involved in activation of important host genes. In this study, analysis of the effects on cellular gene expression revealed that CTAR1 significantly affected cellular expression in part through effects on a specific form of NF-κB. The data suggest that LMP1 can activate a distinct subset of host gene expression through its CTAR1 domain which in combination with other signaling effects induced by the CTAR2 domain likely affects cell movement, survival, and growth.
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12
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Raab-Traub N. Nasopharyngeal Carcinoma: An Evolving Role for the Epstein-Barr Virus. Curr Top Microbiol Immunol 2015; 390:339-63. [PMID: 26424653 DOI: 10.1007/978-3-319-22822-8_14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Epstein-Barr herpesvirus (EBV) is an important human pathogen that is closely linked to several major malignancies including the major epithelial tumor, undifferentiated nasopharyngeal carcinoma (NPC). This important tumor occurs with elevated incidence in specific areas, particularly in southern China but also in Mediterranean Africa and some regions of the Middle East. Regardless of tumor prevalence, undifferentiated NPC is consistently associated with EBV. The consistent detection of EBV in all cases of NPC, the maintenance of the viral genome in every cell, and the continued expression of viral gene products suggest that EBV is a necessary factor for the malignant growth in vivo. However, the molecular characterization of the infection and identification of critical events have been hampered by the difficulty in developing in vitro models of NPC. Epithelial cell infection is difficult in vitro and in contrast to B-cell infection does not result in immortalization and transformation. Cell lines established from NPC usually do not retain the genome, and the successful establishment of tumor xenografts is difficult. However, critical genetic changes that contribute to the onset and progression of NPC and key molecular properties of the viral genes expressed in NPC have been identified. In some cases, viral expression becomes increasingly restricted during tumor progression and tumor cells may express only the viral nuclear antigen EBNA1 and viral noncoding RNAs. As NPC develops in the immunocompetent, the continued progression of deregulated growth likely reflects the combination of expression of viral oncogenes in some cells and viral noncoding RNAs that likely function synergistically with changes in cellular RNA and miRNA expression.
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Affiliation(s)
- Nancy Raab-Traub
- Department of Microbiology, Lineberger Comprehensive Cancer Center, CB#7295, University of North Carolina, Chapel Hill, NC, 27599-7295, USA.
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13
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Sokratous K, Hadjisavvas A, Diamandis EP, Kyriacou K. The role of ubiquitin-binding domains in human pathophysiology. Crit Rev Clin Lab Sci 2014; 51:280-90. [PMID: 24901807 DOI: 10.3109/10408363.2014.915287] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ubiquitination, a fundamental post-translational modification (PTM) resulting in the covalent attachment of ubiquitin (Ub) to a target protein, is currently implicated in several key cellular processes. Although ubiquitination was initially associated with protein degradation, it is becoming increasingly evident that proteins labeled with polyUb chains of specific topology and length are activated in an ever-expanding repertoire of specific cellular processes. In addition to their involvement in the classical protein degradation pathways they are involved in DNA repair, kinase regulation and nuclear factor-κB (NF-κB) signaling. The sorting and processing of distinct Ub signals is mediated by small protein motifs, known as Ub-binding domains (UBDs), which are found in proteins that execute disparate biological functions. The involvement of UBDs in several biological pathways has been revealed by several studies which have highlighted the vital role of UBDs in cellular homeostasis. Importantly, functional impairment of UBDs in key regulatory pathways has been related to the development of pathophysiological conditions, including immune disorders and cancer. In this review, we present an up-to-date account of the crucial role of UBDs and their functions, with a special emphasis on their functional impairment in key biological pathways and the pathogenesis of several human diseases. The still under-investigated topic of Ub-UBD interactions as a target for developing novel therapeutic strategies against many diseases is also discussed.
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14
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Anti-viral tetris: modulation of the innate anti-viral immune response by A20. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 809:49-64. [PMID: 25302365 DOI: 10.1007/978-1-4939-0398-6_4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The A20 protein has emerged as an important negative regulator of Toll like receptor (TLR) and retinoic acid-inducible gene 1 (RIG-I)-mediated anti-viral signaling. A20 functions both as a RING-type E3 ubiquitin ligase and as a de-ubiquitinating enzyme. Nuclear factor kappa B (NF-kappaB) and interferon regulatory factor (IRF) pathways are targeted by A20 through mechanisms that appear to be both overlapping and distinct, resulting in the downregulation of interferon alpha/beta (IFNalpha/beta) production. This review specifically details the impact of A20 on the cytosolic RIG-I/MDA5 pathway, a process that is less understood than that of NF-kappaB but is essential for the regulation of the innate immune response to viral infection.
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15
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Arcipowski KM, Stunz LL, Graham JP, Kraus ZJ, Bush TJV, Bishop GA. Molecular mechanisms of TNFR-associated factor 6 (TRAF6) utilization by the oncogenic viral mimic of CD40, latent membrane protein 1 (LMP1). J Biol Chem 2011; 286:9948-55. [PMID: 21262968 PMCID: PMC3060549 DOI: 10.1074/jbc.m110.185983] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 01/19/2011] [Indexed: 11/06/2022] Open
Abstract
Latent membrane protein 1 (LMP1), encoded by Epstein-Barr virus, is required for EBV-mediated B cell transformation and plays a significant role in the development of posttransplant B cell lymphomas. LMP1 has also been implicated in exacerbation of autoimmune diseases such as systemic lupus erythematosus. LMP1 is a constitutively active functional mimic of the tumor necrosis factor receptor superfamily member CD40, utilizing tumor necrosis factor receptor-associated factor (TRAF) adaptor proteins to induce signaling. However, LMP1-mediated B cell activation is amplified and sustained compared with CD40. We have previously shown that LMP1 and CD40 use TRAFs 1, 2, 3, and 5 differently. TRAF6 is important for CD40 signaling, but the role of TRAF6 in LMP1 signaling in B cells is not clear. Although TRAF6 binds directly to CD40, TRAF6 interaction with LMP1 in B cells has not been characterized. Here we tested the hypothesis that TRAF6 is a critical regulator of LMP1 signaling in B cells, either as part of a receptor-associated complex and/or as a cytoplasmic adaptor protein. Using TRAF6-deficient B cells, we determined that TRAF6 was critical for LMP1-mediated B cell activation. Although CD40-mediated TRAF6-dependent signaling does not require the TRAF6 receptor-binding domain, we found that LMP1 signaling required the presence of this domain. Furthermore, TRAF6 was recruited to the LMP1 signaling complex via the TRAF1/2/3/5 binding site within the cytoplasmic domain of LMP1.
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MESH Headings
- Animals
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- B-Lymphocytes/virology
- CD40 Antigens/genetics
- CD40 Antigens/immunology
- CD40 Antigens/metabolism
- Cell Transformation, Viral/genetics
- Cell Transformation, Viral/immunology
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/immunology
- Herpesvirus 4, Human/metabolism
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/immunology
- Lupus Erythematosus, Systemic/metabolism
- Lupus Erythematosus, Systemic/virology
- Lymphocyte Activation/genetics
- Lymphocyte Activation/immunology
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell/metabolism
- Lymphoma, B-Cell/virology
- Mice
- Mice, Knockout
- Molecular Mimicry/genetics
- Molecular Mimicry/immunology
- Protein Structure, Tertiary
- Signal Transduction/immunology
- TNF Receptor-Associated Factor 6/genetics
- TNF Receptor-Associated Factor 6/immunology
- TNF Receptor-Associated Factor 6/metabolism
- Viral Matrix Proteins/genetics
- Viral Matrix Proteins/immunology
- Viral Matrix Proteins/metabolism
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Affiliation(s)
- Kelly M. Arcipowski
- From the Interdisciplinary Graduate Programs in Molecular and Cellular Biology and
| | | | | | | | | | - Gail A. Bishop
- From the Interdisciplinary Graduate Programs in Molecular and Cellular Biology and
- Immunology and
- the Departments of Microbiology and
- Internal Medicine, University of Iowa and
- the Veterans Affairs Medical Center, Iowa City, Iowa 52242
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16
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Abstract
Nuclear factor-kappa B (NF-κB) is a critical regulator of multiple biological functions including innate and adaptive immunity and cell survival. Activation of NF-κB is tightly regulated to preclude chronic signaling that may lead to persistent inflammation and cancer. Ubiquitination of key signaling molecules by E3 ubiquitin ligases has emerged as an important regulatory mechanism for NF-κB signaling. Deubiquitinases (DUBs) counteract E3 ligases and therefore play a prominent role in the downregulation of NF-κB signaling and homeostasis. Understanding the mechanisms of NF-κB downregulation by specific DUBs such as A20 and CYLD may provide therapeutic opportunities for the treatment of chronic inflammatory diseases and cancer.
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Affiliation(s)
- Edward W Harhaj
- Department of Microbiology and Immunology, Sylvester Comprehensive Cancer Center, The University of Miami, Miller School of Medicine, 1550 NW 10 Avenue, Miami, FL 33136, USA.
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17
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Epstein-Barr latent membrane protein 1 transformation site 2 activates NF-kappaB in the absence of NF-kappaB essential modifier residues 133-224 or 373-419. Proc Natl Acad Sci U S A 2010; 107:18103-8. [PMID: 20923877 DOI: 10.1073/pnas.1011752107] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Epstein Barr virus latent membrane protein 1 (LMP1) induces NF-κB activation through transformation effector sites (TES) 1 and 2, both of which are critical for B-lymphocyte transformation. TES2 principally activates canonical NF-κB, which we confirm is NF-κB essential modifier (NEMO)-dependent and requires an intact ubiquitin binding in A20 binding inhibitor of NF-κB and NEMO (UBAN) domain. LMP1 TES2 activated NF-κB in Jurkat cell lines harboring NEMO truncated at 372 (A45) or NEMO with an in-frame deletion of 133-224 (2C), whereas TNFα, 12-O-Tetradecanoylphorbol-13-acetate, human T-cell leukemia virus 1 Tax, and CD40 did not. In both A45 and 2C Jurkat cell lines, LMP1 TES2-mediated NF-κB activation was blocked by siRNAs to TNFα receptor-associated factor 6 and NEMO, by IκB kinase inhibitors, and by the IκBα superrepressor, indicating that the NEMO mutants function to support canonical NF-κB activation. Expression of A45 or 2C mutants in NEMO-deficient murine embryonic fibroblasts reproduced the Jurkat phenotypes: LMP1 TES2 activated NF-κB in fibroblasts lacking NEMO amino acids 133-224 or 373-419, but TNFα and Tax did not. Further analysis indicated that TES2 did not activate NF-κB in cells expressing the double deletion mutant Δ133-224/Δ372-419. These data provide further evidence of the essential role for NEMO in LMP1 TES2 NF-κB activation and highlight the importance of unique domains within NEMO for sensing distinct NF-κB stimuli.
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18
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Song YJ, Kang MS. Roles of TRAF2 and TRAF3 in Epstein-Barr virus latent membrane protein 1-induced alternative NF-kappaB activation. Virus Genes 2010; 41:174-80. [PMID: 20585848 DOI: 10.1007/s11262-010-0505-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 06/14/2010] [Indexed: 11/29/2022]
Abstract
Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1)-induced NF-kappaB activation is essential for EBV-transformed B cell survival. LMP1 has two C-terminal cytoplasmic domains referred to as C-Terminal Activation Regions (CTAR) 1 and 2 that activate the alternative and canonical NF-kappaB pathways, respectively. While CTAR2 activates TRAF6, IKKbeta and IKKgamma-dependent canonical NF-kappaB pathway, CTAR1 interacts with TRAF2 and TRAF3 and activates NIK and IKKalpha-dependent alternative NF-kappaB pathway involving p100 processing into functional p52. Using IKKalpha(-/-), IKKbeta(-/-), IKKgamma(-/-), TRAF2(-/-), TRAF3(-/-), TRAF6(-/-), and NIK(aly/aly) mouse embryonic fibroblasts (MEFs), potential roles of these proteins in LMP1-induced alternative NF-kappaB activation were investigated. Deficiency in IKKalpha or functional NIK, but not in IKKbeta, IKKgamma, or TRAF6, severely impaired LMP1-induced p100 processing. Notably, p100 was constitutively processed in TRAF2(-/-) or TRAF3(-/-) MEFs independently of LMP1 suggesting that TRAF2 or TRAF3 may play a regulatory role in p100 processing. Subsequently, TRAF2 or TRAF3 over-expression in HEK293 cells significantly blocked LMP1-induced p100 processing. The LMP1 CTAR1 expression in 293HEK cells activated the alternative p65/p52 complex while CTAR2 failed to do so. Taken together, LMP1 activates alternative NF-kappaB pathway through functional NIK and IKKalpha that is regulated by TRAF2 or TRAF3.
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Affiliation(s)
- Yoon-Jae Song
- Department of Life Science, Kyungwon University, Kyeonggi-Do, Korea.
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19
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Abstract
Clinicians have suspected for hundreds of years that chronic activation of the immune system contributes to the development of cancer. However, the molecular mechanisms that mediate this precarious interplay are only now being elucidated. Recent reports have identified A20 as a crucial tumour suppressor in various lymphomas. A20 is a ubiquitin-editing enzyme that attenuates the activity of proximal signalling complexes at pro-inflammatory receptors. In this Review we summarize the evidence linking chronic inflammation with tumorigenesis and consider how A20 modulates inflammatory signalling cascades, thereby providing a mechanism to explain how deregulation of ubiquitylation can promote tumorigenesis.
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Affiliation(s)
- Sarah G Hymowitz
- Department of Structural Biology, Genentech, Inc.1 DNA Way, M/S 40, South San Francisco, CA 94080, USA
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20
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Abstract
A20 possesses both deubiquitinase (DUB) and ubiquitin E3 ligase activities that are required for termination of Toll-like receptor (TLR) signaling leading to NF-kappaB activation and for blockage of tumor necrosis factor (TNF)-induced cytotoxicity and apoptosis. A20 is induced by the Epstein-Barr virus (EBV) oncoprotein LMP1. However, its dual ubiquitin-editing activities have not been investigated in the context of either EBV infection or IRF7 responses. Both A20 and IRF7 have oncogenic properties. We have recently shown that LMP1 activates IRF7 through K63-linked ubiquitination which requires RIP1 and TRAF6, but how this ubiquitination event is regulated has not been studied. Here, we show that A20 negatively regulates IRF7 transcriptional activity induced by LMP1. Deletion or mutation of A20 C-terminal zinc finger motifs had no effect on the inhibition of IRF7 activity, whereas DUB-deficient truncation or point mutation ablated the ability of A20 to inhibit IRF7. Correspondingly, the A20 N-terminal DUB domain, but not the C-terminal E3 ligase domain, interacts physically with IRF7. Transient expression of A20 reduced K63-linked ubiquitination of IRF7 in vivo, but an in vitro deubiquitination assay with purified constituents shows that IRF7 did not act as a substrate for A20 DUB activity. Moreover, A20 interacts with IRF7 endogenously in latently EBV-infected type 3 Raji cells, in which expression of both A20 and IRF7 is constitutively induced by the considerable level of endogenous LMP1. Knockdown of endogenous A20 in Raji cells by expression of A20 short hairpin RNA (shRNA) vectors increases endogenous IRF7 activity and ubiquitination, as well as the protein level of LMP1, a target of IRF7. Thus, A20 negatively regulates LMP1-stimulated IRF7 ubiquitination and activity in EBV latency, and its DUB activity is indispensable for this function. Finally, we discussed the regulation and function of IRFs in EBV latency.
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21
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Frequent inactivation of A20 in B-cell lymphomas. Nature 2009; 459:712-6. [PMID: 19412163 DOI: 10.1038/nature07969] [Citation(s) in RCA: 429] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 03/03/2009] [Indexed: 12/24/2022]
Abstract
A20 is a negative regulator of the NF-kappaB pathway and was initially identified as being rapidly induced after tumour-necrosis factor-alpha stimulation. It has a pivotal role in regulation of the immune response and prevents excessive activation of NF-kappaB in response to a variety of external stimuli; recent genetic studies have disclosed putative associations of polymorphic A20 (also called TNFAIP3) alleles with autoimmune disease risk. However, the involvement of A20 in the development of human cancers is unknown. Here we show, using a genome-wide analysis of genetic lesions in 238 B-cell lymphomas, that A20 is a common genetic target in B-lineage lymphomas. A20 is frequently inactivated by somatic mutations and/or deletions in mucosa-associated tissue lymphoma (18 out of 87; 21.8%) and Hodgkin's lymphoma of nodular sclerosis histology (5 out of 15; 33.3%), and, to a lesser extent, in other B-lineage lymphomas. When re-expressed in a lymphoma-derived cell line with no functional A20 alleles, wild-type A20, but not mutant A20, resulted in suppression of cell growth and induction of apoptosis, accompanied by downregulation of NF-kappaB activation. The A20-deficient cells stably generated tumours in immunodeficient mice, whereas the tumorigenicity was effectively suppressed by re-expression of A20. In A20-deficient cells, suppression of both cell growth and NF-kappaB activity due to re-expression of A20 depended, at least partly, on cell-surface-receptor signalling, including the tumour-necrosis factor receptor. Considering the physiological function of A20 in the negative modulation of NF-kappaB activation induced by multiple upstream stimuli, our findings indicate that uncontrolled signalling of NF-kappaB caused by loss of A20 function is involved in the pathogenesis of subsets of B-lineage lymphomas.
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22
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Malynn BA, Ma A. A20 takes on tumors: tumor suppression by an ubiquitin-editing enzyme. ACTA ACUST UNITED AC 2009; 206:977-80. [PMID: 19380636 PMCID: PMC2715039 DOI: 10.1084/jem.20090765] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Many B cell cancers are characterized in part by the dysregulation of the NF-kappaB signaling pathway. A new study identifies somatic mutations in TNFAIP3, the gene encoding the NF-kappaB inhibitor A20, in Hodgkin lymphomas and primary mediastinal lymphomas. These data reveal the role of A20 as a tumor suppressor protein.
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Affiliation(s)
- Barbara A Malynn
- Program in Biomedical Sciences, Program in Biological Sciences, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
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23
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Li L, Guo L, Tao Y, Zhou S, Wang Z, Luo W, Hu D, Li Z, Xiao L, Tang M, Yi W, Tsao SW, Cao Y. Latent membrane protein 1 of Epstein-Barr virus regulates p53 phosphorylation through MAP kinases. Cancer Lett 2007; 255:219-31. [PMID: 17582679 DOI: 10.1016/j.canlet.2007.04.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2007] [Revised: 04/05/2007] [Accepted: 04/25/2007] [Indexed: 12/27/2022]
Abstract
The Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1), an oncogenic protein, plays an important role in the carcinogenesis of nasopharyngeal carcinoma (NPC). Phosphorylation of p53 protein is likely to play the key role in regulating its activity. p53 protein accumulates but mutation of p53 gene is not common in NPC. The molecular mechanisms of p53 augmentation have not been completely elucidated. Here, the role of MAP kinases in the phosphorylation of p53 modulated by LMP1 was determined. p53 could be activated and phosphorylated clearly at Ser15, Ser20, Ser392, and Thr81 modulated by LMP1. Furthermore, LMP1-induced phosphorylation of p53 at Ser15 was directly by ERKs; at Ser20 and Thr81 by JNK, at Ser 15 and Ser392 by p38 kinase. The phosphorylation of p53 was associated with its transcriptional activity and stability modulated by LMP1. These results strongly suggest that MAP kinases have a direct role in LMP1-induced phosphorylation of p53 at multiple sites, which provide a novel view for us to understand the mechanism of the activation of p53 in the carcinogenesis of nasopharyngeal carcinoma.
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Affiliation(s)
- Lili Li
- Cancer Research Institute, Xiangya School of Medicine, Central South University, 110 Xiangya Road, Changsha, Hunan, PR China
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24
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Devaraj SG, Wang N, Chen Z, Chen Z, Tseng M, Barretto N, Lin R, Peters CJ, Tseng CTK, Baker SC, Li K. Regulation of IRF-3-dependent innate immunity by the papain-like protease domain of the severe acute respiratory syndrome coronavirus. J Biol Chem 2007; 282:32208-21. [PMID: 17761676 PMCID: PMC2756044 DOI: 10.1074/jbc.m704870200] [Citation(s) in RCA: 305] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) is a novel coronavirus that causes a highly contagious respiratory disease, SARS, with significant mortality. Although factors contributing to the highly pathogenic nature of SARS-CoV remain poorly understood, it has been reported that SARS-CoV infection does not induce type I interferons (IFNs) in cell culture. However, it is uncertain whether SARS-CoV evades host detection or has evolved mechanisms to counteract innate host defenses. We show here that infection of SARS-CoV triggers a weak IFN response in cultured human lung/bronchial epithelial cells without inducing the phosphorylation of IFN-regulatory factor 3 (IRF-3), a latent cellular transcription factor that is pivotal for type I IFN synthesis. Furthermore, SARS-CoV infection blocked the induction of IFN antiviral activity and the up-regulation of protein expression of a subset of IFN-stimulated genes triggered by double-stranded RNA or an unrelated paramyxovirus. In searching for a SARS-CoV protein capable of counteracting innate immunity, we identified the papain-like protease (PLpro) domain as a potent IFN antagonist. The inhibition of the IFN response does not require the protease activity of PLpro. Rather, PLpro interacts with IRF-3 and inhibits the phosphorylation and nuclear translocation of IRF-3, thereby disrupting the activation of type I IFN responses through either Toll-like receptor 3 or retinoic acid-inducible gene I/melanoma differentiation-associated gene 5 pathways. Our data suggest that regulation of IRF-3-dependent innate antiviral defenses by PLpro may contribute to the establishment of SARS-CoV infection.
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Affiliation(s)
- Santhana G Devaraj
- Department of Microbiology and Immunology, Center of Biodefense and Emerging Infectious Diseases, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-1019, USA
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25
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Shi W, Li L, Shi X, Zheng F, Zeng J, Jiang X, Gong F, Zhou M, Li Z. Inhibition of nuclear factor-kappaB activation is essential for membrane-associated TNF-alpha-induced apoptosis in HL-60 cells. Immunol Cell Biol 2006; 84:366-73. [PMID: 16594899 DOI: 10.1111/j.1440-1711.2006.01436.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The killing of tumour cells that are resistant to soluble TNF-alpha (sTNF-alpha) by the membrane-bound form of TNF-alpha (mTNF-alpha) suggests that different intracellular signalling pathways are involved. We found that mTNF-alpha induced apoptosis in HL-60 cells and failed to cause degradation of inhibitor of kappa B alpha (IkappaB-alpha) and translocation and activation of nuclear factor kappa B (NF-kappaB), whereas sTNF-alpha failed to induce apoptosis, but lowered cytoplasmic inhibitor of kappa B alpha, induced translocation of NF-kappaB to the nucleus and experimentally increased activity of the regulated luciferase. Furthermore, mTNF-alpha upregulated the expression of TNF receptor associated factor (TRAF) 1 and failed to induce TRAF1 and TRAF2 membrane translocation, but led to cytoplasmic colocalization. In contrast, sTNF-alpha stimulated the expression of TRAF1 and TRAF2, recruiting both molecules onto the cell membrane poststimulation. These results suggest that the increased susceptibility of HL-60 cells to mTNF-alpha may be due to the failure of TRAF2 membrane translocation caused by the upregulation of TRAF1 expression and formation of a TRAF1/TRAF2 complex in the cytoplasm, thereby inhibiting NF-kappaB activation and inducing apoptosis.
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Affiliation(s)
- Wenfang Shi
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
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26
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Yuan J, Cahir-McFarland E, Zhao B, Kieff E. Virus and cell RNAs expressed during Epstein-Barr virus replication. J Virol 2006; 80:2548-65. [PMID: 16474161 PMCID: PMC1395376 DOI: 10.1128/jvi.80.5.2548-2565.2006] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Changes in Epstein-Barr virus (EBV) and cell RNA levels were assayed following immunoglobulin G (IgG) cross-linking-induced replication in latency 1-infected Akata Burkitt B lymphoblasts. EBV replication as assayed by membrane gp350 expression was approximately 5% before IgG cross-linking and increased to more than 50% 48 h after induction. Seventy-two hours after IgG cross-linking, gp350-positive cells excluded propidium iodide as well as gp350-negative cells. EBV RNA levels changed temporally in parallel with previously defined sensitivity to inhibitors of protein or viral DNA synthesis. BZLF1 immediate-early RNA levels doubled by 2 h and reached a peak at 4 h, whereas BMLF1 doubled by 4 h with a peak at 8 h, and BRLF1 doubled by 8 h with peak at 12 h. Early RNAs peaked at 8 to 12 h, and late RNAs peaked at 24 h. Hybridization to intergenic sequences resulted in evidence for new EBV RNAs. Surprisingly, latency III (LTIII) RNAs for LMP1, LMP2, EBNALP, EBNA2, EBNA3A, EBNA3C, and BARTs were detected at 8 to 12 h and reached maxima at 24 to 48 h. EBNA2 and LMP1 were at full LTIII levels by 48 h and localized to gp350-positive cells. Thus, LTIII expression is a characteristic of late EBV replication in both B lymphoblasts and epithelial cells in immune-comprised people (J. Webster-Cyriaque, J. Middeldorp, and N. Raab-Traub, J. Virol. 74:7610-7618, 2000). EBV replication significantly altered levels of 401 Akata cell RNAs, of which 122 RNAs changed twofold or more relative to uninfected Akata cells. Mitogen-activated protein kinase levels were significantly affected. Late expression of LTIII was associated with induction of NF-kappaB responsive genes including IkappaBalpha and A20. The exclusion of propidium, expression of EBV LTIII RNAs and proteins, and up-regulation of specific cell RNAs are indicative of vital cell function late in EBV replication.
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Affiliation(s)
- Jing Yuan
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Channing Laboratory, Boston, MA 02115, USA
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27
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Esparza EM, Arch RH. Glucocorticoid-Induced TNF Receptor, a Costimulatory Receptor on Naive and Activated T Cells, Uses TNF Receptor-Associated Factor 2 in a Novel Fashion as an Inhibitor of NF-κB Activation. THE JOURNAL OF IMMUNOLOGY 2005; 174:7875-82. [PMID: 15944293 DOI: 10.4049/jimmunol.174.12.7875] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Glucocorticoid-induced TNFR (GITR) has been implicated as an essential regulator of immune responses to self tissues and pathogens. We have recently shown that GITR-induced cellular events promote survival of naive T cells, but are insufficient to protect against activation-induced cell death. However, the molecular mechanisms of GITR-induced signal transduction that influence physiologic and pathologic immune responses are not well understood. TNFR-associated factors (TRAFs) are pivotal adapter proteins involved in signal transduction pathways of TNFR-related proteins. Yeast two-hybrid assays and studies in HEK293 cells and primary lymphocytes indicated interactions between TRAF2 and GITR mediated by acidic residues in the cytoplasmic domain of the receptor. GITR-induced activation of NF-kappaB is blocked by A20, an NF-kappaB-inducible protein that interacts with TRAFs and functions in a negative feedback mechanism downstream of other TNFRs. Interestingly, in contrast with its effects on signaling triggered by other TNFRs, our functional studies revealed that TRAF2 plays a novel inhibitory role in GITR-triggered NF-kappaB activation.
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MESH Headings
- Amino Acid Sequence
- Animals
- Carrier Proteins/physiology
- Cell Line
- Conserved Sequence
- Cysteine Endopeptidases
- Cytoplasm/chemistry
- Cytoplasm/metabolism
- DNA-Binding Proteins
- Down-Regulation/genetics
- Down-Regulation/immunology
- Glucocorticoid-Induced TNFR-Related Protein
- Humans
- Hydrogen-Ion Concentration
- Intracellular Signaling Peptides and Proteins
- Lymphocyte Activation/genetics
- Lymphocyte Activation/immunology
- Mice
- Mice, Transgenic
- Molecular Sequence Data
- NF-kappa B/antagonists & inhibitors
- NF-kappa B/metabolism
- Nuclear Proteins
- Protein Structure, Tertiary/genetics
- Protein Transport/genetics
- Protein Transport/immunology
- Proteins/pharmacology
- Receptors, Nerve Growth Factor/antagonists & inhibitors
- Receptors, Nerve Growth Factor/metabolism
- Receptors, Nerve Growth Factor/physiology
- Receptors, Tumor Necrosis Factor/antagonists & inhibitors
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor/physiology
- Resting Phase, Cell Cycle/genetics
- Resting Phase, Cell Cycle/immunology
- TNF Receptor-Associated Factor 2/metabolism
- TNF Receptor-Associated Factor 2/physiology
- Transfection
- Tumor Necrosis Factor alpha-Induced Protein 3
- Tumor Necrosis Factors
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Affiliation(s)
- Edward M Esparza
- Department of Medicine, School of Medicine, Washington University, St. Louis, MO 63110, USA
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28
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Siegler G, Meyer B, Dawson C, Brachtel E, Lennerz J, Koch C, Kremmer E, Niedobitek E, Gonnella R, Pilch BZ, Young LS, Niedobitek G. Expression of tumor necrosis factor receptor-associated factor 1 in nasopharyngeal carcinoma: possible upregulation by Epstein-Barr virus latent membrane protein 1. Int J Cancer 2004; 112:265-72. [PMID: 15352039 DOI: 10.1002/ijc.20367] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
EBV infection is associated with virtually all cases of undifferentiated NPC, and the EBV-encoded LMP1 is expressed in a proportion of cases. LMP1 has transforming functions similar to members of the TNF receptor family and activates intracellular signaling cascades through interaction with TRAFs. In B cells, expression of TRAF1 is in turn upregulated by LMP1. LMP1 signaling in epithelial cells may be affected by the presence or absence of TRAF1. By immunohistochemistry, we detected TRAF1 expression in 17 of 42 (40%) EBV+ undifferentiated NPCs. All 7 LMP1+ NPC biopsies were also TRAF1+. Using an RNAse protection assay, high-level TRAF1 expression was detected in an LMP1-expressing NPC-derived cell line (C15) and expression was weaker in 2 LMP1- cell lines (C17, C19). Finally, LMP1 upregulated TRAF1 expression in an EBV- keratinocyte cell line. Our results demonstrate that TRAF1 is expressed in NPC tumor cells in vivo and suggest that TRAF1 expression may be upregulated by LMP1 in NPC. An antiapoptotic function has been proposed for TRAF1, and this may be relevant for the pathogenesis of NPC.
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Affiliation(s)
- Gabriele Siegler
- Institute for Pathology, Friedrich-Alexander-University, Erlangen, Germany
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29
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Song X, Tao YG, Deng XY, Jin X, Tan YN, Tang M, Wu Q, Lee LM, Cao Y. Heterodimer formation between c-Jun and Jun B proteins mediated by Epstein–Barr virus encoded latent membrane protein 1. Cell Signal 2004; 16:1153-62. [PMID: 15240010 DOI: 10.1016/j.cellsig.2004.03.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Accepted: 03/15/2004] [Indexed: 11/22/2022]
Abstract
Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1) is essential for the immortalization of human B cells and is linked etiologically to several human tumors. LMP1 is an integral membrane protein which acts like a constitutively active receptor. It binds tumor necrosis factor (TNF)-receptor-associated factors (TRAFs), activates NFkappaB and triggers the transcription factor activating protein-1 (AP-1) via the c-Jun N-terminal kinase (JNK) cascade, but its specific contribution to AP-1 has not been elucidated fully. Members of AP-1 family, the Jun and fos related protein, have been shown to directly interact and form heterodimeric complexes. In this report, using a Tet-on LMP1 HNE2 cell line which is a dual-stable LMP1 integrated nasopharyngeal carcinoma (NPC) cell line and the expression of LMP1 in which could be regulated by Tet-on system, we show that Jun B can efficiently form a new heterodimeric complex with the c-Jun protein under the regulation of LMP1, phosphorylation of c-Jun (ser63, ser73) and Jun B involved in the process of the new heterodimeric form. We also find that this heterodimeric form can bind to the AP-1 consensus sequence. Transfection studies suggest that JNK interaction protein (JIP) could inhibit the heterodimer form of c-Jun and Jun B through blocking the AP-1 signaling pathway triggered by LMP1. The interaction and function between c-Jun protein and Jun B protein increase the repertoire of possible regulatory complexes by LMP1 that could play an important role in the regulation of transcription of specific cellular genes in the process of genesis of nasopharyngeal carcinoma.
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Affiliation(s)
- Xin Song
- Cancer Research Institute, Xiangya School of Medicine, Central South of University, 88 Xiangya Road, Changsha 410078, China
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30
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Lang V, Symons A, Watton SJ, Janzen J, Soneji Y, Beinke S, Howell S, Ley SC. ABIN-2 forms a ternary complex with TPL-2 and NF-kappa B1 p105 and is essential for TPL-2 protein stability. Mol Cell Biol 2004; 24:5235-48. [PMID: 15169888 PMCID: PMC419892 DOI: 10.1128/mcb.24.12.5235-5248.2004] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
NF-kappa B1 p105 forms a high-affinity, stoichiometric interaction with TPL-2, a MEK kinase essential for TLR4 activation of the ERK mitogen-activated protein kinase cascade in lipopolysaccharide (LPS)-stimulated macrophages. Interaction with p105 is required to maintain TPL-2 metabolic stability and also negatively regulates TPL-2 MEK kinase activity. Here, affinity purification identified A20-binding inhibitor of NF-kappa B 2 (ABIN-2) as a novel p105-associated protein. Cotransfection experiments demonstrated that ABIN-2 could interact with TPL-2 in addition to p105 but preferentially formed a ternary complex with both proteins. Consistently, in unstimulated bone marrow-derived macrophages (BMDMs), a substantial fraction of endogenous ABIN-2 was associated with both p105 and TPL-2. Although the majority of TPL-2 in these cells was complexed with ABIN-2, the pool of TPL-2 which could activate MEK after LPS stimulation was not, and LPS activation of TPL-2 was found to correlate with its release from ABIN-2. Depletion of ABIN-2 by RNA interference dramatically reduced steady-state levels of TPL-2 protein without affecting levels of TPL-2 mRNA or p105 protein. In addition, ABIN-2 increased the half-life of cotransfected TPL-2. Thus, optimal TPL-2 stability in vivo requires interaction with ABIN-2 as well as p105. Together, these data raise the possibility that ABIN-2 functions in the TLR4 signaling pathway which regulates TPL-2 activation.
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Affiliation(s)
- V Lang
- Division of Immune Cell Biology, National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom
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31
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Fang CY, Chang YS, Chow KP, Yu JS, Chang HY. Construction and characterization of monoclonal antibodies specific to Epstein-Barr virus latent membrane protein 1. J Immunol Methods 2004; 287:21-30. [PMID: 15099753 DOI: 10.1016/j.jim.2004.01.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 11/24/2003] [Accepted: 01/15/2004] [Indexed: 10/26/2022]
Abstract
Epstein-Barr virus (EBV) has been implicated in the development of many human neoplasias including B lymphomas and nasopharyngeal carcinoma (NPC). The EBV latent membrane protein 1 (LMP-1) has been found to participate in diverse cellular signaling pathways and is essential for virus-induced B-cell immortalization. In order to determine quantitatively the amount of LMP-1 in cells, five monoclonal antibodies (Mabs) specific to LMP-1 were generated. The epitopes recognized by these Mabs were found to cluster within the repeat region between the CTAR1 and CTAR2 domains, corresponding to amino acid positions 254-319 of LMP-1. These Mabs were capable of recognizing LMP-1 proteins of both lymphoid and epithelial origin as revealed by immunoblot, enzyme-linked immunosorbent assay (ELISA) and immunocytofluorescence analysis. A sandwich ELISA for the quantification of LMP-1 has been established using these Mabs. Taken together, our results indicate that the Mabs generated in this study are suitable for the detection of LMP-1 in biomedical research.
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Affiliation(s)
- Chih-Yeu Fang
- Institute of Molecular Medicine, National Tsing Hua University, Hsin-chu 300, Taiwan, ROC
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32
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D'Souza BN, Edelstein LC, Pegman PM, Smith SM, Loughran ST, Clarke A, Mehl A, Rowe M, Gélinas C, Walls D. Nuclear factor kappa B-dependent activation of the antiapoptotic bfl-1 gene by the Epstein-Barr virus latent membrane protein 1 and activated CD40 receptor. J Virol 2004; 78:1800-16. [PMID: 14747545 PMCID: PMC369510 DOI: 10.1128/jvi.78.4.1800-1816.2004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Suppression of the cellular apoptotic program by the oncogenic herpesvirus Epstein-Barr virus (EBV) is central to both the establishment of latent infection and the development of EBV-associated malignancies. We have previously shown that expression of the EBV latent membrane protein 1 (LMP1) in Burkitt's lymphoma cell lines leads to increased mRNA levels from the cellular antiapoptotic bfl-1 gene (also known as A1). Furthermore, ectopic expression of Bfl-1 in an EBV-positive cell line exhibiting a latency type 1 infection protects against apoptosis induced by growth factor deprivation (B. N. D'Souza, M. Rowe, and D. Walls, J. Virol. 74:6652-6658, 2000). We now report that LMP1 drives bfl-1 promoter activity through interactions with components of the tumor necrosis factor receptor (TNFR)/CD40 signaling pathway. We present evidence that this process is NF-kappa B dependent, involves the recruitment of TNFR-associated factor 2, and is mediated to a greater extent by the carboxyl-terminal activating region 2 (CTAR2) relative to the CTAR1 domain of LMP1. Activation of CD40 receptor also led to increased bfl-1 mRNA levels and an NF-kappa B-dependent increase in bfl-1 promoter activity in Burkitt's lymphoma-derived cell lines. We have delineated a 95-bp region of the promoter that functions as an LMP1-dependent transcriptional enhancer in this cellular context. This sequence contains a novel NF-kappa B-like binding motif that is essential for transactivation of bfl-1 by LMP1, CD40, and the NF-kappa B subunit protein p65. These findings highlight the role of LMP1 as a mediator of EBV-host cell interactions and may indicate an important route by which it exerts its cellular growth transforming properties.
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Affiliation(s)
- Brendan N D'Souza
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
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33
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Geha RS, Jabara HH, Brodeur SR. The regulation of immunoglobulin E class-switch recombination. Nat Rev Immunol 2003; 3:721-32. [PMID: 12949496 DOI: 10.1038/nri1181] [Citation(s) in RCA: 316] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Immunoglobulin E (IgE) isotype antibodies are associated with atopic disease, namely allergic rhinitis, asthma and atopic dermatitis, but are also involved in host immune defence mechanisms against parasitic infection. The commitment of a B cell to isotype class switch to an IgE-producing cell is a tightly regulated process, and our understanding of the regulation of IgE-antibody production is central to the prevention and treatment of atopic disease. Both those that are presently in use and potential future therapies to prevent IgE-mediated disease take advantage of our existing knowledge of the specific mechanisms that are required for IgE class switching.
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Affiliation(s)
- Raif S Geha
- Division of Immunology, Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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34
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Siegler G, Kremmer E, Gonnella R, Niedobitek G. Epstein-Barr virus encoded latent membrane protein 1 (LMP1) and TNF receptor associated factors (TRAF): colocalisation of LMP1 and TRAF1 in primary EBV infection and in EBV associated Hodgkin lymphoma. Mol Pathol 2003; 56:156-61. [PMID: 12782762 PMCID: PMC1187311 DOI: 10.1136/mp.56.3.156] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS Epstein-Barr virus (EBV) immortalises B cells in vitro and is associated with several malignancies. Most phenotypic effects of EBV are mediated by latent membrane protein 1 (LMP1), which interacts with tumour necrosis factor receptor associated factors (TRAFs) to activate NF-kappaB. This study examines TRAF1 and LMP1 expression in EBV associated lymphoproliferations. METHODS TRAF1 expression was investigated in 26 Hodgkin lymphomas (HL; 18 EBV+, eight EBV-), seven EBV+ Burkitt lymphomas (BL), two infectious mononucleosis (IM) tonsils, and lymphoreticular tissue from eight chronic virus carriers. Seven anaplastic large cell lymphomas and 10 follicular B cell lymphomas were also studied. Colocalisation of TRAF1 and LMP1 was studied by immunofluorescent double labelling and confocal laser microscopy. RESULTS TRAF1 colocalises with LMP1 in EBV infected cells in IM. EBV positive lymphocytes from chronic virus carriers were negative for TRAF1 and LMP1. In HL biopsies, TRAF1 was strongly expressed independently of EBV status, whereas all BL cases were TRAF1-. In EBV+ HL cases, TRAF1 colocalised with LMP1. Eight of 10 follicular lymphomas expressed TRAF1 in centroblast-like cells. Four of seven anaplastic large cell lymphomas weakly expressed TRAF1. CONCLUSIONS These results suggest that in non-neoplastic lymphocytes, TRAF1 expression is dependent on the presence of LMP1, and that in IM B cells in vivo, LMP1 associated signalling pathways are active. In HL, TRAF1 is expressed independently of EBV status, probably because of constitutive NF-kappaB activation. The function of TRAF1 in HL remains to be determined.
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Affiliation(s)
- G Siegler
- Institute for Pathology, Friedrich-Alexander-University, Krankenhausstr. 8-10, 91054 Erlangen, Germany
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35
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Tsao SW, Tramoutanis G, Dawson CW, Lo AKF, Huang DP. The significance of LMP1 expression in nasopharyngeal carcinoma. Semin Cancer Biol 2002; 12:473-87. [PMID: 12450733 DOI: 10.1016/s1044579x02000901] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) is a key effector of EBV-mediated B cell transformation. LMP1 displays potent oncogenic properties in rodent fibroblasts, and induces a wide range of effects in B cells and epithelial cells. LMP1 functions as a constitutively active tumor necrosis factor receptor (TNFR) engaging a multitude of signaling pathways that include NF-kappaB, the mitogen-activated protein kinases (MAPKs), JNK, p38, the JAK/STAT pathway and, more recently, the small Rho GTPases. The constitutive activation of these signaling cascades explains LMP1's ability to induce such a diverse array of morphological and phenotypic effects in cells and provides an insight into how LMP1 may induce cell transformation. The frequent expression of LMP1 in undifferentiated nasopharyngeal carcinoma (NPC) points to a role for this viral oncoprotein as a key effector molecule in NPC pathogenesis.
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Affiliation(s)
- Sai Wah Tsao
- Department of Anatomy, Faculty of Medicine, University of Hong Kong, Hong Kong, PR China.
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36
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Abstract
The oncogenic Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) has structural features and functions reminiscent of a constitutively active TNF family receptor. LMP1 aggregates at the plasma membrane and initiates the activation of signalling pathways, such as NF- kappa B, the mitogen-activated protein kinases JNK and p38, the small GTPase Cdc42 and the JAK/STAT cascade. The constitutive engagement of these signals and the characteristic molecular interactions that regulate them provide the basis for the molecular explanation of the transforming properties of this key EBV protein.
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Affiliation(s)
- A G Eliopoulos
- CRC Institute for Cancer Studies, The University of Birmingham Medical School, Birmingham, B15 2TA, UK.
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37
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Yang HJ, Cho YJ, Kim HS, Chang MS, Sung MW, Kim WH. Association of p53 and BCL-2 expression with Epstein-Barr virus infection in the cancers of head and neck. Head Neck 2001; 23:629-36. [PMID: 11443745 DOI: 10.1002/hed.1089] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Reports that have both evaluated the site-specific Epstein-Barr virus (EBV) infection and compared it with the expression of the EBV-related proto-oncogenes and tumor suppressor genes in the various cancers of head and neck are scarce. METHODS Thirty-eight nasopharyngeal carcinoma (NPC) cases, 32 oropharyngeal or hypopharyngeal carcinoma (OPC/HPC) cases, and 93 laryngeal carcinoma (LC) cases were evaluated with in situ hybridization on EBV-encoded small RNA (EBER) and immunohistochemical assessments of the p53, bcl-2, and epidermal growth factor receptor (EGFR) by use of formalin-fixed paraffin-embedded tissue array slides. RESULTS The expression of viral EBERs was observed in more than two thirds (71.1%) of the NPC cases. In contrast, only 1 case of OPC and none of the HPC or LC cases exhibited EBV positivity. In the nonkeratinizing NPC, the EBV positivity was significantly associated with both frequent p53 overexpression (p =.033) and bcl-2 expression (p =.001). In the EBV-positive nonkeratinizing NPC, a correlation between p53 overexpression and the tumor infiltration lymphocyte (TIL) density was noted (p =.012). CONCLUSIONS A site-specific expression of viral EBER was demonstrated in the head and neck cancers, which suggests an important role for both p53 and bcl-2 in the carcinogenesis of an EBV-infected NPC. The correlation between p53 overexpression and the TIL density in the EBV-infected NPC suggests that the product of a lymphoepithelial interaction, such as A20, can induce a dysfunctional p53 protein.
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Affiliation(s)
- H J Yang
- Department of Pathology, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-799, Korea
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38
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Damania B, Jung JU. Comparative analysis of the transforming mechanisms of Epstein-Barr virus, Kaposi's sarcoma-associated herpesvirus, and Herpesvirus saimiri. Adv Cancer Res 2001; 80:51-82. [PMID: 11034540 DOI: 10.1016/s0065-230x(01)80012-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Members of the gamma herpesvirus family include the lymphocryptoviruses (gamma-1 herpesviruses) and the rhadinoviruses (gamma-2 herpesviruses). Gammaherpesvirinae uniformly establish long-term, latent, reactivatable infection of lymphocytes, and several members of the gamma herpesviruses are associated with lymphoproliferative diseases. Epstein-Barr virus is a lymphocryptovirus, whereas Kaposi sarcoma-associated herpesvirus and Herpesvirus saimiri are members of the rhadinovirus family. Genes encoded by these viruses are involved in a diverse array of cellular signaling pathways. This review attempts to cover our understanding of how viral proteins deregulate cellular signaling pathways that ultimately contribute to the conversion of normal cells to cancerous cells.
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Affiliation(s)
- B Damania
- Department of Microbiology and Molecular Genetics, New England Regional Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772, USA
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39
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Abstract
Low doses of oxidative stress can induce cellular resistance to subsequent higher doses of the same stress. By using human U937 leukemia cells, we previously demonstrated that H(2)O(2) can induce such an adaptive response without elevating the cellular capacity to degrade H(2)O(2), and were able to confer the cells a cross-resistance to an H(2)O(2)-independent lethal stimulus, C(2)-ceramide. In this study, it was found that the adaptation is accompanied by the translocation of cytoplasmic NF-kappa B to the nuclei. This event was promoted or abolished when either IKK alpha or a dominant negative mutant of I kappa B, respectively, was overexpressed. The overexpression of IKK alpha also resulted in the suppression of H(2)O(2)-induced cell death and DNA fragmentation, whereas these events were accelerated by the expression of the I kappa B mutant. The protective effect of IKK alpha was accompanied neither by an elevation of protein levels of various antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase, nor by an increase in the cellular capacity to consume H(2)O(2). Moreover, the overexpression of IKK alpha resulted in an enhancement of H(2)O(2)-induced resistance to C(2)-ceramide. The overall data suggest that NF-kappa B mediates the H(2)O(2) adaptation induced in a manner independent of H(2)O(2)-degrading activity.
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Affiliation(s)
- D K Kim
- Laboratory of Cell Biology, Yonsei Medical Research Center, Yonsei University College of Medicine, Seoul, South Korea
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40
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Meij P, Vervoort MB, Meijer CJ, Bloemena E, Middeldorp JM. Production monitoring and purification of EBV encoded latent membrane protein 1 expressed and secreted by recombinant baculovirus infected insect cells. J Virol Methods 2000; 90:193-204. [PMID: 11064119 DOI: 10.1016/s0166-0934(00)00233-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1) is expressed in malignancies with latency type II and III and is an important transforming protein. To further study this protein LMP1 was expressed by and purified from recombinant baculovirus infected Sf9 cells. Expression levels of LMP1 in EBV transformed B cell lines and Sf9 cells were analyzed using a newly developed quantitative LMP1-capture ELISA. Highest expression was found in the cell line X50/7 (6.2 ng/10(7) cells), whereas expression levels of recombinant LMP1 (bLMP1) in Sf9 cells reached 506 ng/10(7) cells. Surprisingly bLMP1 could also be detected in the culture medium as a stable full-length protein. Highest expression in Sf9 cells (506 ng/10(7) cells) was observed at 48 h post infection and in the culture medium (1590 ng/ml) at 96 h post infection. Before purification bLMP1 was solubilised using 0.22 m octyl-beta-glucoside at pH 6.0. Purification of bLMP1 using Q-Sepharose FF yielded 10-80 times enriched bLMP1 fractions, indicating that Q-Sepharose can be used for pre-purification. A one-step monoclonal antibody based immunoaffinity chromatography yielded highly purified bLMP1. Although the overall yields (20 microg purified LMP1 from 100 ml culture supernatant) and protein concentrations were low, higher concentrations of >95% purified BLMP1 could be reached after freeze drying.
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Affiliation(s)
- P Meij
- Department of Pathology, University Hospital Vrije Universiteit, Amsterdam, The Netherlands.
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41
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Kawanishi M. The Epstein-Barr virus latent membrane protein 1 (LMP1) enhances TNF alpha-induced apoptosis of intestine 407 epithelial cells: the role of LMP1 C-terminal activation regions 1 and 2. Virology 2000; 270:258-66. [PMID: 10792984 DOI: 10.1006/viro.2000.0296] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) can protect some kinds of lymphocytes from apoptotic cell death. In contrast, the present study showed that the expression of LMP1 induced high susceptibility to tumor necrosis factor alpha (TNFalpha)-induced apoptosis in intestine 407 epithelial cells, without affecting expression of TNF receptors I and II. LMP1-deletion mutants lacking either C-terminal activation region (CTAR)-1 or CTAR-2 had ability to enhance TNFalpha-induced apoptosis, whereas the deletion of both activation regions completely abolished the induction of high susceptibility to TNFalpha. Phosphorylation of the NFkB-inhibitory molecule IkB-alpha, another biological activity of TNFalpha, was not enhanced by LMP1-expression. LMP1 upregulated antiapoptotic gene A20 expression, suggesting that A20 can not block TNFalpha-induced apoptosis in this cell system. Apoptosis triggered by TNFalpha in LMP1-expressing intestine 407 cells was blocked by inhibitors of caspases-8 and -3. It is therefore concluded that in intestine 407 epithelial cells, LMP1 enhances primarily signal cascade responsible for TNFalpha-induced apoptosis, which occurs at a level upstream of acting site of caspases-8 and -3 and that CTAR-1 and CTAR-2 are involved in enhancement of TNFalpha-induced apoptosis.
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Affiliation(s)
- M Kawanishi
- Department of Microbiology, Kyoto University, Kyoto, 606-8315, Japan.
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