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Zhao B. Epstein-Barr Virus B Cell Growth Transformation: The Nuclear Events. Viruses 2023; 15:832. [PMID: 37112815 PMCID: PMC10146190 DOI: 10.3390/v15040832] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 03/29/2023] Open
Abstract
Epstein-Barr virus (EBV) is the first human DNA tumor virus identified from African Burkitt's lymphoma cells. EBV causes ~200,000 various cancers world-wide each year. EBV-associated cancers express latent EBV proteins, EBV nuclear antigens (EBNAs), and latent membrane proteins (LMPs). EBNA1 tethers EBV episomes to the chromosome during mitosis to ensure episomes are divided evenly between daughter cells. EBNA2 is the major EBV latency transcription activator. It activates the expression of other EBNAs and LMPs. It also activates MYC through enhancers 400-500 kb upstream to provide proliferation signals. EBNALP co-activates with EBNA2. EBNA3A/C represses CDKN2A to prevent senescence. LMP1 activates NF-κB to prevent apoptosis. The coordinated activity of EBV proteins in the nucleus allows efficient transformation of primary resting B lymphocytes into immortalized lymphoblastoid cell lines in vitro.
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Affiliation(s)
- Bo Zhao
- Department of Medicine, Division of Infectious Diseases, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
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2
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Jhang JF, Liu CD, Hsu YH, Chen CC, Chen HC, Jiang YH, Wu WC, Peng CW, Kuo HC. EBV infection mediated BDNF expression is associated with bladder inflammation in interstitial cystitis/bladder pain syndrome with Hunner's lesion. J Pathol 2023; 259:276-290. [PMID: 36441149 DOI: 10.1002/path.6040] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/31/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022]
Abstract
Interstitial cystitis/bladder pain syndrome with Hunner's lesion (HIC) is characterized by chronic inflammation and nerve hyperplasia; however, the pathogenesis of HIC remains a mystery. In this study, we detected both Epstein-Barr virus (EBV) latency infection genes EBNA-1 and LMP-1 and EBV lytic infection BZLF-1 and BRLF-1 expression in the HIC bladders, indicating the coexistence of EBV persistence and reactivation in the B cells in HIC bladders. Upregulation of EBV-associated inflammatory genes in HIC bladders, such as TNF-α and IL-6, suggests EBV infection is implicated in the pathogenesis of bladder inflammation. Nerve hyperplasia and upregulation of brain-derived neurotrophic factor (BDNF) were noted in the HIC bladders. Double immunochemical staining and flow cytometry revealed the origin of BDNF to be EBV-infected B cells. Inducible BDNF expression was noted in B cells upon EBV infection, but not in the T cells. A chromatin immunoprecipitation study revealed BDNF transcription could be promoted by cooperation between EBV nuclear antigens, chromatin modifiers, and B-cell-specific transcription. Knockdown of BDNF in EBV-infected B cells resulted in the inhibition of cell proliferation and viability. Downregulation of phosphorylated SMAD2 and STAT3 after BDNF knockdown may play a role in the mechanism. Implantation of latent EBV-infected B cells into rat bladder walls resulted in a higher expression level of CD45 and PGP9.5, suggesting tissue inflammation and nerve hyperplasia. In contrast, implantation of BDNF depleted EBV-infected B cells abrogated these effects. This is the first study to provide insights into the mechanisms underlying the involvement of EBV-infected B cells in HIC pathogenesis. © 2022 The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Jia-Fong Jhang
- Department of Urology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.,Department of Urology, School of Medicine, Tzu Chi University, Hualien, Taiwan.,Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Cheng-Der Liu
- Department of Life Science, National Donghwa University, Shoufeng, Taiwan
| | - Yung-Hsiang Hsu
- Department of Pathology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.,Department of Pathology, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Chien-Chin Chen
- Department of Pathology, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi, Taiwan.,Department of Cosmetic Science, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.,Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Hsiang-Chin Chen
- Department of Life Science, National Donghwa University, Shoufeng, Taiwan
| | - Yuan-Hong Jiang
- Department of Urology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.,Department of Urology, School of Medicine, Tzu Chi University, Hualien, Taiwan.,Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Wan-Chen Wu
- Department of Life Science, National Donghwa University, Shoufeng, Taiwan
| | - Chih-Wen Peng
- Department of Life Science, National Donghwa University, Shoufeng, Taiwan
| | - Hann-Chorng Kuo
- Department of Urology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.,Department of Urology, School of Medicine, Tzu Chi University, Hualien, Taiwan.,Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
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3
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Ambrose AJ, Chapman E. Function, Therapeutic Potential, and Inhibition of Hsp70 Chaperones. J Med Chem 2021; 64:7060-7082. [PMID: 34009983 DOI: 10.1021/acs.jmedchem.0c02091] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hsp70s are among the most highly conserved proteins in all of biology. Through an iterative binding and release of exposed hydrophobic residues on client proteins, Hsp70s can prevent aggregation and promote folding to the native state of their client proteins. The human proteome contains eight canonical Hsp70s. Because Hsp70s are relatively promiscuous they play a role in folding a large proportion of the proteome. Hsp70s are implicated in disease through their ability to regulate protein homeostasis. In recent years, researchers have attempted to develop selective inhibitors of Hsp70 isoforms to better understand the role of individual isoforms in biology and as potential therapeutics. Selective inhibitors have come from rational design, forced localization, and serendipity, but the development of completely selective inhibitors remains elusive. In the present review, we discuss the Hsp70 structure and function, the known Hsp70 client proteins, the role of Hsp70s in disease, and current efforts to discover Hsp70 modulators.
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Affiliation(s)
- Andrew J Ambrose
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Eli Chapman
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
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4
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Wang C, Li D, Zhang L, Jiang S, Liang J, Narita Y, Hou I, Zhong Q, Zheng Z, Xiao H, Gewurz BE, Teng M, Zhao B. RNA Sequencing Analyses of Gene Expression during Epstein-Barr Virus Infection of Primary B Lymphocytes. J Virol 2019; 93:e00226-19. [PMID: 31019051 PMCID: PMC6580941 DOI: 10.1128/jvi.00226-19] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/05/2019] [Indexed: 12/23/2022] Open
Abstract
Epstein-Barr virus (EBV) infection of human primary resting B lymphocytes (RBLs) leads to the establishment of lymphoblastoid cell lines (LCLs) that can grow indefinitely in vitro EBV transforms RBLs through the expression of viral latency genes, and these genes alter host transcription programs. To globally measure the transcriptome changes during EBV transformation, primary human resting B lymphocytes (RBLs) were infected with B95.8 EBV for 0, 2, 4, 7, 14, 21, and 28 days, and poly(A) plus RNAs were analyzed by transcriptome sequencing (RNA-seq). Analyses of variance (ANOVAs) found 3,669 protein-coding genes that were differentially expressed (false-discovery rate [FDR] < 0.01). Ninety-four percent of LCL genes that are essential for LCL growth and survival were differentially expressed. Pathway analyses identified a significant enrichment of pathways involved in cell proliferation, DNA repair, metabolism, and antiviral responses. RNA-seq also identified long noncoding RNAs (lncRNAs) differentially expressed during EBV infection. Clustered regularly interspaced short palindromic repeat (CRISPR) interference (CRISPRi) and CRISPR activation (CRISPRa) found that CYTOR and NORAD lncRNAs were important for LCL growth. During EBV infection, type III EBV latency genes were expressed rapidly after infection. Immediately after LCL establishment, EBV lytic genes were also expressed in LCLs, and ∼4% of the LCLs express gp350. Chromatin immune precipitation followed by deep sequencing (ChIP-seq) and POLR2A chromatin interaction analysis followed by paired-end tag sequencing (ChIA-PET) data linked EBV enhancers to 90% of EBV-regulated genes. Many genes were linked to enhancers occupied by multiple EBNAs or NF-κB subunits. Incorporating these assays, we generated a comprehensive EBV regulome in LCLs.IMPORTANCE Epstein-Barr virus (EBV) immortalization of resting B lymphocytes (RBLs) is a useful model system to study EBV oncogenesis. By incorporating transcriptome sequencing (RNA-seq), chromatin immune precipitation followed by deep sequencing (ChIP-seq), chromatin interaction analysis followed by paired-end tag sequencing (ChIA-PET), and genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screen, we identified key pathways that EBV usurps to enable B cell growth and transformation. Multiple layers of regulation could be achieved by cooperations between multiple EBV transcription factors binding to the same enhancers. EBV manipulated the expression of most cell genes essential for lymphoblastoid cell line (LCL) growth and survival. In addition to proteins, long noncoding RNAs (lncRNAs) regulated by EBV also contributed to LCL growth and survival. The data presented in this paper not only allowed us to further define the molecular pathogenesis of EBV but also serve as a useful resource to the EBV research community.
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Affiliation(s)
- Chong Wang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Difei Li
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Luyao Zhang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Department of Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Sizun Jiang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jun Liang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Yohei Narita
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Isabella Hou
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Qian Zhong
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Zeguang Zheng
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Haipeng Xiao
- Department of Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Benjamin E Gewurz
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Mingxiang Teng
- Department of Biostatistics and Bioinformatics, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
| | - Bo Zhao
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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5
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Increase of Hspa1a and Hspa1b genes in the resting B cells of Sirt1 knockout mice. Mol Biol Rep 2019; 46:4225-4234. [DOI: 10.1007/s11033-019-04876-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/14/2019] [Indexed: 01/12/2023]
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6
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Wang C, Zhou H, Xue Y, Liang J, Narita Y, Gerdt C, Zheng AY, Jiang R, Trudeau S, Peng CW, Gewurz BE, Zhao B. Epstein-Barr Virus Nuclear Antigen Leader Protein Coactivates EP300. J Virol 2018; 92:e02155-17. [PMID: 29467311 PMCID: PMC5899200 DOI: 10.1128/jvi.02155-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 02/10/2018] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus nuclear antigen (EBNA) leader protein (EBNALP) is one of the first viral genes expressed upon B-cell infection. EBNALP is essential for EBV-mediated B-cell immortalization. EBNALP is thought to function primarily by coactivating EBNA2-mediated transcription. Chromatin immune precipitation followed by deep sequencing (ChIP-seq) studies highlight that EBNALP frequently cooccupies DNA sites with host cell transcription factors (TFs), in particular, EP300, implicating a broader role in transcription regulation. In this study, we investigated the mechanisms of EBNALP transcription coactivation through EP300. EBNALP greatly enhanced EP300 transcription activation when EP300 was tethered to a promoter. EBNALP coimmunoprecipitated endogenous EP300 from lymphoblastoid cell lines (LCLs). EBNALP W repeat serine residues 34, 36, and 63 were required for EP300 association and coactivation. Deletion of the EP300 histone acetyltransferase (HAT) domain greatly reduced EBNALP coactivation and abolished the EBNALP association. An EP300 bromodomain inhibitor also abolished EBNALP coactivation and blocked the EP300 association with EBNALP. EBNALP sites cooccupied by EP300 had significantly higher ChIP-seq signals for sequence-specific TFs, including SPI1, RelA, EBF1, IRF4, BATF, and PAX5. EBNALP- and EP300-cooccurring sites also had much higher H3K4me1 and H3K27ac signals, indicative of activated enhancers. EBNALP-only sites had much higher signals for DNA looping factors, including CTCF and RAD21. EBNALP coactivated reporters under the control of NF-κB or SPI1. EP300 inhibition abolished EBNALP coactivation of these reporters. Clustered regularly interspaced short palindromic repeat interference targeting of EBNALP enhancer sites significantly reduced target gene expression, including that of EP300 itself. These data suggest a previously unrecognized mechanism by which EBNALP coactivates transcription through subverting of EP300 and thus affects the expression of LCL genes regulated by a broad range of host TFs.IMPORTANCE Epstein-Barr virus was the first human DNA tumor virus discovered over 50 years ago. EBV is causally linked to ∼200,000 human malignancies annually. These cancers include endemic Burkitt lymphoma, Hodgkin lymphoma, lymphoma/lymphoproliferative disease in transplant recipients or HIV-infected people, nasopharyngeal carcinoma, and ∼10% of gastric carcinoma cases. EBV-immortalized human B cells faithfully model key aspects of EBV lymphoproliferative diseases and are useful models of EBV oncogenesis. EBNALP is essential for EBV to transform B cells and transcriptionally coactivates EBNA2 by removing repressors from EBNA2-bound DNA sites. Here, we found that EBNALP can also modulate the activity of the key transcription activator EP300, an acetyltransferase that activates a broad range of transcription factors. Our data suggest that EBNALP regulates a much broader range of host genes than was previously appreciated. A small-molecule inhibitor of EP300 abolished EBNALP coactivation of multiple target genes. These findings suggest novel therapeutic approaches to control EBV-associated lymphoproliferative diseases.
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Affiliation(s)
- Chong Wang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Hufeng Zhou
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Yong Xue
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jun Liang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Yohei Narita
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Catherine Gerdt
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Amy Y Zheng
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Runsheng Jiang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Stephen Trudeau
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Chih-Wen Peng
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Benjamin E Gewurz
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Bo Zhao
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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7
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New Interactors of the Truncated EBNA-LP Protein Identified by Mass Spectrometry in P3HR1 Burkitt's Lymphoma Cells. Cancers (Basel) 2018; 10:cancers10010012. [PMID: 29303964 PMCID: PMC5789362 DOI: 10.3390/cancers10010012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 01/07/2023] Open
Abstract
The Epstein-Barr virus nuclear antigen leader protein (EBNA-LP) acts as a co-activator of EBNA-2, a transcriptional activator essential for Epstein-Barr virus (EBV)-induced B-cell transformation. Burkitt's lymphoma (BL) cells harboring a mutant EBV strain that lacks both the EBNA-2 gene and 3' exons of EBNA-LP express Y1Y2-truncated isoforms of EBNA-LP (tEBNA-LP) and better resist apoptosis than if infected with the wild-type virus. In such BL cells, tEBNA-LP interacts with the protein phosphatase 2A (PP2A) catalytic subunit (PP2A C), and this interaction likely plays a role in resistance to apoptosis. Here, 28 cellular and four viral proteins have been identified by mass spectrometry as further possible interactors of tEBNA-LP. Three interactions were confirmed by immunoprecipitation and Western blotting, namely with the A structural subunit of PP2A (PP2A A), the structure-specific recognition protein 1 (SSRP1, a component of the facilitate chromatin transcription (FACT) complex), and a new form of the transcription factor EC (TFEC). Thus, tEBNA-LP appears to be involved not only in cell resistance to apoptosis through its interaction with two PP2A subunits, but also in other processes where its ability to co-activate transcriptional regulators could be important.
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8
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Shen CL, Liu CD, You RI, Ching YH, Liang J, Ke L, Chen YL, Chen HC, Hsu HJ, Liou JW, Kieff E, Peng CW. Ribosome Protein L4 is essential for Epstein-Barr Virus Nuclear Antigen 1 function. Proc Natl Acad Sci U S A 2016; 113:2229-34. [PMID: 26858444 PMCID: PMC4776490 DOI: 10.1073/pnas.1525444113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Epstein-Barr Virus (EBV) Nuclear Antigen 1 (EBNA1)-mediated origin of plasmid replication (oriP) DNA episome maintenance is essential for EBV-mediated tumorigenesis. We have now found that EBNA1 binds to Ribosome Protein L4 (RPL4). RPL4 shRNA knockdown decreased EBNA1 activation of an oriP luciferase reporter, EBNA1 DNA binding in lymphoblastoid cell lines, and EBV genome number per lymphoblastoid cell line. EBV infection increased RPL4 expression and redistributed RPL4 to cell nuclei. RPL4 and Nucleolin (NCL) were a scaffold for an EBNA1-induced oriP complex. The RPL4 N terminus cooperated with NCL-K429 to support EBNA1 and oriP-mediated episome binding and maintenance, whereas the NCL C-terminal K380 and K393 induced oriP DNA H3K4me2 modification and promoted EBNA1 activation of oriP-dependent transcription. These observations provide new insights into the mechanisms by which EBV uses NCL and RPL4 to establish persistent B-lymphoblastoid cell infection.
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Affiliation(s)
- Chih-Lung Shen
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan
| | - Cheng-Der Liu
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan
| | - Ren-In You
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Yung-Hao Ching
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Jun Liang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115
| | - Liangru Ke
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115
| | - Ya-Lin Chen
- Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Hong-Chi Chen
- Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Hao-Jen Hsu
- Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Je-Wen Liou
- Institute of Biochemical Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Elliott Kieff
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115;
| | - Chih-Wen Peng
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan; Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan;
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9
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Harter MR, Liu CD, Shen CL, Gonzalez-Hurtado E, Zhang ZM, Xu M, Martinez E, Peng CW, Song J. BS69/ZMYND11 C-Terminal Domains Bind and Inhibit EBNA2. PLoS Pathog 2016; 12:e1005414. [PMID: 26845565 PMCID: PMC4742278 DOI: 10.1371/journal.ppat.1005414] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 01/04/2016] [Indexed: 12/20/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) plays an important role in driving immortalization of EBV-infected B cells through regulating the expression of many viral and cellular genes. We report a structural study of the tumor suppressor BS69/ZMYND11 C-terminal region, comprised of tandem coiled-coil-MYND domains (BS69CC-MYND), in complex with an EBNA2 peptide containing a PXLXP motif. The coiled-coil domain of BS69 self-associates to bring two separate MYND domains in close proximity, thereby enhancing the BS69 MYND-EBNA2 interaction. ITC analysis of BS69CC-MYND with a C-terminal fragment of EBNA2 further suggests that the BS69CC-MYND homodimer synergistically binds to the two EBNA2 PXLXP motifs that are respectively located in the conserved regions CR7 and CR8. Furthermore, we showed that EBNA2 interacts with BS69 and down-regulates its expression at both mRNA and protein levels in EBV-infected B cells. Ectopic BS69CC-MYND is recruited to viral target promoters through interactions with EBNA2, inhibits EBNA2-mediated transcription activation, and impairs proliferation of lymphoblastoid cell lines (LCLs). Substitution of critical residues in the MYND domain impairs the BS69-EBNA2 interaction and abolishes the BS69 inhibition of the EBNA2-mediated transactivation and LCL proliferation. This study identifies the BS69 C-terminal domains as an inhibitor of EBNA2, which may have important implications in development of novel therapeutic strategies against EBV infection. Since the discovery of Epstein-Barr virus (EBV) 50 years ago, the etiologic links between EBV and a variety of human cancers have gained wide recognition. It is estimated that >90% of the worldwide population carry this virus, which causes over 200,000 cancers across the world every year. One of the key proteins in driving immortalization of EBV-infected B cells is Epstein-Barr virus nuclear antigen 2 (EBNA2), which regulates the expression of many cellular and viral genes. However, the molecular mechanism underlying the interactions between EBNA2 and cellular transcriptional regulators remains enigmatic. Here, we determined the crystal structure of the coiled-coil and MYND tandem domains of BS69/ZMYND11, a candidate tumor suppressor, in complex with an EBNA2 peptide containing a PXLXP motif. We found that the coiled-coil and MYND domains of BS69 cooperate in binding to EBNA2. We also showed that EBNA2 interacts with BS69 and down-regulates its expression at both mRNA and protein levels in EBV-associated B cells. Ectopic BS69 coiled-coil-MYND dual domain is recruited to viral target promoters through interaction with EBNA2, inhibits EBNA2-mediated transcription activation, and impairs proliferation of lymphoblastoid cell lines (LCLs). Together, this study identifies the BS69 C-terminal domains as an inhibitor of EBNA2.
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Affiliation(s)
- Matthew R. Harter
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
| | - Cheng-Der Liu
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Chih-Lung Shen
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Elsie Gonzalez-Hurtado
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
- MARC U-STAR Program, University of California, Riverside, Riverside, California, United States of America
| | - Zhi-Min Zhang
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
| | - Muyu Xu
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
| | - Ernest Martinez
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
- MARC U-STAR Program, University of California, Riverside, Riverside, California, United States of America
| | - Chih-Wen Peng
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
- * E-mail: (CWP); (JS)
| | - Jikui Song
- Department of Biochemistry, University of California, Riverside, Riverside, California, United States of America
- * E-mail: (CWP); (JS)
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Abstract
While all herpesviruses can switch between lytic and latent life cycle, which are both driven by specific transcription programs, a unique feature of latent EBV infection is the expression of several distinct and well-defined viral latent transcription programs called latency I, II, and III. Growth transformation of B-cells by EBV in vitro is based on the concerted action of Epstein-Barr virus nuclear antigens (EBNAs) and latent membrane proteins(LMPs). EBV growth-transformed B-cells express a viral transcriptional program, termed latency III, which is characterized by the coexpression of EBNA2 and EBNA-LP with EBNA1, EBNA3A, -3B, and -3C as well as LMP1, LMP2A, and LMP2B. The focus of this review will be to discuss the current understanding of how two of these proteins, EBNA2 and EBNA-LP, contribute to EBV-mediated B-cell growth transformation.
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Affiliation(s)
- Bettina Kempkes
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Marchioninistr. 25, 81377, Munich, Germany.
| | - Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA.
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11
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Epstein-Barr virus nuclear antigen leader protein localizes to promoters and enhancers with cell transcription factors and EBNA2. Proc Natl Acad Sci U S A 2013; 110:18537-42. [PMID: 24167291 DOI: 10.1073/pnas.1317608110] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigens EBNALP (LP) and EBNA2 (E2) are coexpressed in EBV-infected B lymphocytes and are critical for lymphoblastoid cell line outgrowth. LP removes NCOR and RBPJ repressive complexes from promoters, enhancers, and matrix-associated deacetylase bodies, whereas E2 activates transcription from distal enhancers. LP ChIP-seq analyses identified 19,224 LP sites of which ~50% were ± 2 kb of a transcriptional start site. LP sites were enriched for B-cell transcription factors (TFs), YY1, SP1, PAX5, BATF, IRF4, ETS1, RAD21, PU.1, CTCF, RBPJ, ZNF143, SMC3, NFκB, TBLR, and EBF. E2 sites were also highly enriched for LP-associated cell TFs and were more highly occupied by RBPJ and EBF. LP sites were highly marked by H3K4me3, H3K27ac, H2Az, H3K9ac, RNAPII, and P300, indicative of activated transcription. LP sites were 29% colocalized with E2 (LP/E2). LP/E2 sites were more similar to LP than to E2 sites in associated cell TFs, RNAPII, P300, and histone H3K4me3, H3K9ac, H3K27ac, and H2Az occupancy, and were more highly transcribed than LP or E2 sites. Gene affected by CTCF and LP cooccupancy were more highly expressed than genes affected by CTCF alone. LP was at myc enhancers and promoters and of MYC regulated ccnd2, 23 med complex components, and MYC regulated cell survival genes, igf2r and bcl2. These data implicate LP and associated TFs and DNA looping factors CTCF, RAD21, SMC3, and YY1/INO80 chromatin-remodeling complexes in repressor depletion and gene activation necessary for lymphoblastoid cell line growth and survival.
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Liu CD, Cheng CP, Fang JS, Chen LC, Zhao B, Kieff E, Peng CW. Modulation of Epstein-Barr virus nuclear antigen 2-dependent transcription by protein arginine methyltransferase 5. Biochem Biophys Res Commun 2012; 430:1097-102. [PMID: 23261437 DOI: 10.1016/j.bbrc.2012.12.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 12/07/2012] [Indexed: 11/24/2022]
Abstract
Epstein-Barr Virus Nuclear Antigen (EBNA) 2 features an Arginine-Glycine repeat (RG) domain at amino acid positions 335-360, which is a known target for protein arginine methyltransferaser 5 (PRMT5). In this study, we performed protein affinity pull-down assays to demonstrate that endogenous PRMT5 derived from lymphoblastoid cells specifically associated with the protein bait GST-E2 RG. Transfection of a plasmid expressing PRMT5 induced a 2.5- to 3-fold increase in EBNA2-dependent transcription of both the LMP1 promoter in AKATA cells, which contain the EBV genome endogenously, and a Cp-Luc reporter plasmid in BJAB cells, which are EBV negative. Furthermore, we showed that there was a 2-fold enrichment of EBNA2 occupancy in target promoters in the presence of exogenous PRMT5. Taken together, we show that PRMT5 triggers the symmetric dimethylation of EBNA2 RG domain to coordinate with EBNA2-mediated transcription. This modulation suggests that PRMT5 may play a role in latent EBV infection.
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Affiliation(s)
- Cheng-Der Liu
- Department of Life Sciences, Tzu-Chi University, 701 Chung-Yang Rd. Sec 3, Hualien 97004, Taiwan
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Liu CD, Chen YL, Min YL, Zhao B, Cheng CP, Kang MS, Chiu SJ, Kieff E, Peng CW. The nuclear chaperone nucleophosmin escorts an Epstein-Barr Virus nuclear antigen to establish transcriptional cascades for latent infection in human B cells. PLoS Pathog 2012; 8:e1003084. [PMID: 23271972 PMCID: PMC3521654 DOI: 10.1371/journal.ppat.1003084] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 10/29/2012] [Indexed: 11/18/2022] Open
Abstract
Epstein-Barr Virus (EBV) is an oncogenic γ-herpesvirus that capably establishes both latent and lytic modes of infection in host cells and causes malignant diseases in humans. Nuclear antigen 2 (EBNA2)-mediated transcription of both cellular and viral genes is essential for the establishment and maintenance of the EBV latency program in B lymphocytes. Here, we employed a protein affinity pull-down and LC-MS/MS analysis to identify nucleophosmin (NPM1) as one of the cellular proteins bound to EBNA2. Additionally, the specific domains that are responsible for protein-protein interactions were characterized as EBNA2 residues 300 to 360 and the oligomerization domain (OD) of NPM1. As in c-MYC, dramatic NPM1 expression was induced in EBV positively infected B cells after three days of viral infection, and both EBNA2 and EBNALP were implicated in the transactivation of the NPM1 promoter. Depletion of NPM1 with the lentivirus-expressed short-hairpin RNAs (shRNAs) effectively abrogated EBNA2-dependent transcription and transformation outgrowth of lymphoblastoid cells. Notably, the ATP-bound state of NPM1 was required to induce assembly of a protein complex containing EBNA2, RBP-Jκ, and NPM1 by stabilizing the interaction of EBNA2 with RBP-Jκ. In a NPM1-knockdown cell line, we demonstrated that an EBNA2-mediated transcription defect was fully restored by the ectopic expression of NPM1. Our findings highlight the essential role of NPM1 in chaperoning EBNA2 onto the latency-associated membrane protein 1 (LMP1) promoters, which is coordinated with the subsequent activation of transcriptional cascades through RBP-Jκ during EBV infection. These data advance our understanding of EBV pathology and further imply that NPM1 can be exploited as a therapeutic target for EBV-associated diseases.
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Affiliation(s)
- Cheng-Der Liu
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Ya-Lin Chen
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Yi-Li Min
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Bo Zhao
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chi-Ping Cheng
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Myung-Soo Kang
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shu-Jun Chiu
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Elliott Kieff
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chih-Wen Peng
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
- * E-mail:
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Lim YS, Shin KS, Oh SH, Kang SM, Won SJ, Hwang SB. Nonstructural 5A protein of hepatitis C virus regulates heat shock protein 72 for its own propagation. J Viral Hepat 2012; 19:353-63. [PMID: 22497815 DOI: 10.1111/j.1365-2893.2011.01556.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We identified heat shock protein 72 (Hsp72) as a host factor that was differentially expressed in cells expressing nonstructural 5A (NS5A) protein. To investigate how NS5A modulates Hsp72 in hepatitis C virus (HCV) life cycle, we examined the role of Hsp72 in HCV replication and virus production. NS5A specifically interacted with Hsp72. Both Hsp72 and nuclear factor of activated T cells 5 (NFAT5) levels were increased in cells expressing NS5A protein. Treatments of N-acetylcysteine and glutathione markedly reduced protein levels of both NFAT5 and Hsp72. Knockdown of NFAT5 resulted in decrease in Hsp72 level in cells expressing NS5A. Importantly, silencing of Hsp72 expression resulted in decrease in both RNA replication and virus production in HCV-infected cells. These data indicate that NS5A modulates Hsp72 via NFAT5 and reactive oxygen species activation for HCV propagation.
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Affiliation(s)
- Y S Lim
- National Research Laboratory of Hepatitis C Virus, Ilsong Institute of Life Science, Hallym University, Anyang, South Korea
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Chen YL, Tsai HL, Peng CW. EGCG debilitates the persistence of EBV latency by reducing the DNA binding potency of nuclear antigen 1. Biochem Biophys Res Commun 2012; 417:1093-9. [DOI: 10.1016/j.bbrc.2011.12.104] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 12/20/2011] [Indexed: 10/14/2022]
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EBV nuclear antigen EBNALP dismisses transcription repressors NCoR and RBPJ from enhancers and EBNA2 increases NCoR-deficient RBPJ DNA binding. Proc Natl Acad Sci U S A 2011; 108:7808-13. [PMID: 21518914 DOI: 10.1073/pnas.1104991108] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
EBV nuclear antigen 2 (EBNA2) and EBV nuclear antigen LP (EBNALP) are critical for B-lymphocyte transformation to lymphoblastoid cell lines (LCLs). EBNA2 activates transcription through recombination signal-binding immunoglobulin κJ region (RBPJ), a transcription factor associated with NCoR repressive complexes, and EBNALP is implicated in repressor relocalization. EBNALP coactivation with EBNA2 was found to dominate over NCoR repression. EBNALP associated with NCoR and dismissed NCoR, NCoR and RBPJ, or NCoR, RBPJ, and EBNA2 from matrix-associated deacetylase (MAD) bodies. In non-EBV-infected BJAB B lymphoma cells that stably express EBNA2, EBNALP, or EBNA2 and EBNALP, EBNALP was associated with hairy and enhancer of split 1 (hes1), cd21, cd23, and arginine and glutamate-rich 1 (arglu1) enhancer or promoter DNA and was associated minimally with coding DNA. With the exception of RBPJ at the arglu1 enhancer, NCoR and RBPJ were significantly decreased at enhancer and promoter sites in EBNALP or EBNA2 and EBNALP BJAB cells. EBNA2 DNA association was unaffected by EBNALP, and EBNALP was unaffected by EBNA2. EBNA2 markedly increased RBPJ at enhancer sites without increasing NCoR. EBNALP further increased hes1 and arglu1 RNA levels with EBNA2 but did not further increase cd21 or cd23 RNA levels. EBNALP in which the 45 C-terminal residues critical for transformation and transcriptional activation were deleted associated with NCoR but was deficient in dismissing NCoR from MAD bodies and from enhancer and promoter sites. These data strongly support a model in which EBNA2 association with NCoR-deficient RBPJ enhances transcription and EBNALP dismisses NCoR and RBPJ repressive complexes from enhancers to coactivate hes1 and arglu1 but not cd21 or cd23.
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Abstract
Measles virus is highly neuroinvasive, yet host immune responses are highly effective at limiting neurovirulence in humans. We know that neurons are an important target of infection and that both IFN-γ and -β expression are observed in the measles virus-infected human brain. Rodent models can be used to understand how this response is orchestrated. Constitutive expression of the major inducible 70-kDa heat-shock protein is a feature of primate tissues that is lacking in mice. This article examines the importance of addressing this difference when modeling outcomes of brain infection in mice, particularly in terms of understanding how infected neurons may activate uninfected brain macrophages to produce IFN-β and support T-cell production of IFN-γ, a mediator of noncytolytic viral clearance. New and historical data suggest that the virus heat-shock protein 70 relationship is key to a protective host immune response and has potential broad relevance.
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Affiliation(s)
- Michael Oglesbee
- Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
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Affiliation(s)
- Christopher G. Evans
- Department of Pathology and the Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Lyra Chang
- Department of Pathology and the Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Jason E. Gestwicki
- Department of Pathology and the Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
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Zhao Y, Kurian D, Xu H, Petherbridge L, Smith LP, Hunt L, Nair V. Interaction of Marek's disease virus oncoprotein Meq with heat-shock protein 70 in lymphoid tumour cells. J Gen Virol 2009; 90:2201-8. [DOI: 10.1099/vir.0.012062-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Stuber G, Flaberg E, Petranyi G, Otvös R, Rökaeus N, Kashuba E, Wiman KG, Klein G, Szekely L. PRIMA-1MET induces nucleolar translocation of Epstein-Barr virus-encoded EBNA-5 protein. Mol Cancer 2009; 8:23. [PMID: 19323829 PMCID: PMC2667484 DOI: 10.1186/1476-4598-8-23] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 03/26/2009] [Indexed: 12/14/2022] Open
Abstract
The low molecular weight compound, PRIMA-1MET restores the transcriptional transactivation function of certain p53 mutants in tumor cells. We have previously shown that PRIMA-1MET induces nucleolar translocation of p53, PML, CBP and Hsp70. The Epstein-Barr virus encoded, latency associated antigen EBNA-5 (also known as EBNA-LP) is required for the efficient transformation of human B lymphocytes by EBV. EBNA-5 associates with p53-hMDM2-p14ARF complexes. EBNA-5 is a nuclear protein that translocates to the nucleolus upon heat shock or inhibition of proteasomes along with p53, hMDM2, Hsp70, PML and proteasome subunits. Here we show that PRIMA-1MET induces the nucleolar translocation of EBNA-5 in EBV transformed B lymphoblasts and in transfected tumor cells. The PRIMA-1MET induced translocation of EBNA-5 is not dependent on the presence of mutant p53. It also occurs in p53 null cells or in cells that express wild type p53. Both the native and the EGFP or DSRed conjugated EBNA-5 respond to PRIMA-1MET treatment in the same way. Image analysis of DSRed-EBNA-5 expressing cells, using confocal fluorescence time-lapse microscopy showed that the nucleolar translocation requires several hours to complete. FRAP (fluorescence recovery after photobleaching) and FLIP (fluorescence loss in photobleaching) measurements on live cells showed that the nucleolar translocation was accompanied by the formation of EBNA-5 aggregates. The process is reversible since the aggregates are dissolved upon removal of PRIMA-1MET. Our results suggest that mutant p53 is not the sole target of PRIMA-1MET. We propose that PRIMA-1MET may reversibly inhibit cellular chaperons that prevent the aggregation of misfolded proteins, and that EBNA-5 may serve as a surrogate drug target for elucidating the precise molecular action of PRIMA-1MET.
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Affiliation(s)
- György Stuber
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute, Stockholm, Sweden.
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Forsman A, Rüetschi U, Ekholm J, Rymo L. Identification of intracellular proteins associated with the EBV-encoded nuclear antigen 5 using an efficient TAP procedure and FT-ICR mass spectrometry. J Proteome Res 2008; 7:2309-19. [PMID: 18457437 DOI: 10.1021/pr700769e] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Epstein-Barr virus nuclear antigen 5 (EBNA5) is one of the first viral proteins detected after primary EBV infection and has been shown to be required for efficient transformation of B lymphocytes. EBNA5 is a protein that has many suggested functions but the underlying biology remains to be clarified. To gain further insight into the biological roles of the proposed multifunctional EBNA5, we isolated EBNA5 containing protein complexes using a modified tandem affinity purification (TAP) method and identified the protein components by LC-MS/MS analysis of tryptic digests on a LTQ-FT-ICR mass spectrometer. The modified TAP tag contained a Protein A domain and a StrepTagII sequence separated by two Tobacco Etch Virus protease cleavage sites and was fused to the C-terminus of EBNA5. Our results confirmed the wide applicability of this two-step affinity purification strategy for purification of protein complexes in mammalian cells. A total of 147 novel putative EBNA5 interaction partners were identified, 37 of which were validated with LC-MS/MS in split-tag experiments or in co-immuno precipitates from HEK293 cell extracts. This subgroup included the Bcl2-associated Athanogene 2 (BAG2) co-chaperone involved in protein folding and renaturation, the 26S proteasome subunit 2 involved in regulation of ubiquitin/proteasome protein degradation, and the heterogeneous ribonucleoprotein M (hnRNP M) involved in pre-mRNA processing. These EBNA5 interactors were further verified by co-immunoprecipitations from cell extracts of three EBV-positive lymphoblastoid lines. The combination of the Hsp70, Hsc70, BAG2 and 26S proteasome subunit 2 interactors suggests that EBNA5 might have a functional relationship with protein quality control systems that recognize proteins with abnormal structures and either refold them to normal conformation or target them for degradation. Our study also confirms previously identified interactors including HA95, Hsp70, Hsc70, Hsp27, HAX-1, Prolyl 4-hydroxylase, S3a, and alpha- and beta-tubulin.
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Affiliation(s)
- Alma Forsman
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
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