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Maestri D, Napoletani G, Kossenkov A, Preston-Alp S, Caruso LB, Tempera I. The three-dimensional structure of the EBV genome plays a crucial role in regulating viral gene expression in EBVaGC. Nucleic Acids Res 2023; 51:12092-12110. [PMID: 37889078 PMCID: PMC10711448 DOI: 10.1093/nar/gkad936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/04/2023] [Accepted: 10/10/2023] [Indexed: 10/28/2023] Open
Abstract
Epstein-Barr virus (EBV) establishes lifelong asymptomatic infection by replication of its chromatinized episomes with the host genome. EBV exhibits different latency-associated transcriptional repertoires, each with distinct three-dimensional structures. CTCF, Cohesin and PARP1 are involved in maintaining viral latency and establishing episome architecture. Epstein-Barr virus-associated gastric cancer (EBVaGC) represents 1.3-30.9% of all gastric cancers globally. EBV-positive gastric cancers exhibit an intermediate viral transcription profile known as 'Latency II', expressing specific viral genes and noncoding RNAs. In this study, we investigated the impact of PARP1 inhibition on CTCF/Cohesin binding in Type II latency. We observed destabilization of the binding of both factors, leading to a disrupted three-dimensional architecture of the episomes and an altered viral gene expression. Despite sharing the same CTCF binding profile, Type I, II and III latencies exhibit different 3D structures that correlate with variations in viral gene expression. Additionally, our analysis of H3K27ac-enriched interactions revealed differences between Type II latency episomes and a link to cellular transformation through docking of the EBV genome at specific sites of the Human genome, thus promoting oncogene expression. Overall, this work provides insights into the role of PARP1 in maintaining active latency and novel mechanisms of EBV-induced cellular transformation.
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Affiliation(s)
- Davide Maestri
- The Wistar Institute, Philadelphia, PA 19104, USA
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
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2
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Looi CK, Foong LC, Chung FFL, Khoo ASB, Loo EM, Leong CO, Mai CW. Targeting the crosstalk of epigenetic modifications and immune evasion in nasopharyngeal cancer. Cell Biol Toxicol 2023; 39:2501-2526. [PMID: 37755585 DOI: 10.1007/s10565-023-09830-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 09/11/2023] [Indexed: 09/28/2023]
Abstract
Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck cancer that is highly associated with Epstein-Barr virus (EBV) infection. EBV acts as an epigenetic driver in NPC tumorigenesis, reprogramming the viral and host epigenomes to regulate viral latent gene expression, and creating an environment conducive to the malignant transformation of nasopharyngeal epithelial cells. Targeting epigenetic mechanisms in pre-clinical studies has been shown promise in eradicating tumours and overcoming immune resistance in some solid tumours. However, its efficacy in NPC remains inclusive due to the complex nature of this cancer. In this review, we provide an updated understanding of the roles of epigenetic factors in regulating EBV latent gene expression and promoting NPC progression. We also explore the crosstalk between epigenetic mechanisms and immune evasion in NPC. Particularly, we discuss the potential roles of DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors in reversing immune suppression and augmenting antitumour immunity. Furthermore, we highlight the advantages of combining epigenetic therapy and immune checkpoint inhibitor to reverse immune resistance and improve clinical outcomes. Epigenetic drugs have the potential to modulate both epigenetic mediators and immune factors involved in NPC. However, further research is needed to fully comprehend the diverse range of epigenetic modifications in NPC. A deeper understanding of the crosstalk between epigenetic mechanisms and immune evasion during NPC progression is crucial for the development of more effective treatments for this challenging disease.
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Affiliation(s)
- Chin-King Looi
- School of Postgraduate Studies, International Medical University, Bukit Jalil, 57000, Kuala Lumpur, Malaysia
| | - Lian-Chee Foong
- State Key Laboratory of Systems Medicine for Cancer, Renji-Med X Clinical Stem Cell Research Center, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Pudong New District, Shanghai, 200127, China
| | - Felicia Fei-Lei Chung
- Department of Medical Sciences, School of Medical and Life Sciences, Sunway University, 47500, Subang Jaya, Selangor, Malaysia
| | - Alan Soo-Beng Khoo
- School of Postgraduate Studies, International Medical University, Bukit Jalil, 57000, Kuala Lumpur, Malaysia
- Department of Medical Oncology, Sidney Kimmel Medical College, Thomas Jefferson University, Pennsylvania, PA, 19107, USA
| | - Ee-Mun Loo
- AGTC Genomics, Bukit Jalil, 57000, Kuala Lumpur, Malaysia
- Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, UCSI University, No. 1, Jalan Menara Gading, UCSI Heights, Cheras, 56000, Kuala Lumpur, Malaysia
| | - Chee-Onn Leong
- AGTC Genomics, Bukit Jalil, 57000, Kuala Lumpur, Malaysia
- Center for Cancer and Stem Cell Research, Development, and Innovation (IRDI), Institute for Research, International Medical University, Bukit Jalil, 57000, Kuala Lumpur, Malaysia
| | - Chun-Wai Mai
- State Key Laboratory of Systems Medicine for Cancer, Renji-Med X Clinical Stem Cell Research Center, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Pudong New District, Shanghai, 200127, China.
- Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, UCSI University, No. 1, Jalan Menara Gading, UCSI Heights, Cheras, 56000, Kuala Lumpur, Malaysia.
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3
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Preston-Alp S, Caruso LB, Su C, Keith K, Soldan SS, Maestri D, Madzo J, Kossenkov A, Napoletani G, Gewurz B, Lieberman PM, Tempera I. Decitabine disrupts EBV genomic epiallele DNA methylation patterns around CTCF binding sites to increase chromatin accessibility and lytic transcription in gastric cancer. mBio 2023; 14:e0039623. [PMID: 37606370 PMCID: PMC10653948 DOI: 10.1128/mbio.00396-23] [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: 02/13/2023] [Accepted: 06/30/2023] [Indexed: 08/23/2023] Open
Abstract
IMPORTANCE Epstein-Barr virus (EBV) latency is controlled by epigenetic silencing by DNA methylation [5-methyl cytosine (5mC)], histone modifications, and chromatin looping. However, how they dictate the transcriptional program in EBV-associated gastric cancers remains incompletely understood. EBV-associated gastric cancer displays a 5mC hypermethylated phenotype. A potential treatment for this cancer subtype is the DNA hypomethylating agent, which induces EBV lytic reactivation and targets hypermethylation of the cellular DNA. In this study, we identified a heterogeneous pool of EBV epialleles within two tumor-derived gastric cancer cell lines that are disrupted with a hypomethylating agent. Stochastic DNA methylation patterning at critical regulatory regions may be an underlying mechanism for spontaneous reactivation. Our results highlight the critical role of epigenetic modulation on EBV latency and life cycle, which is maintained through the interaction between 5mC and the host protein CCCTC-binding factor.
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Affiliation(s)
| | | | - Chenhe Su
- The Wistar Institute, Philadelphia, Pennsylvania, USA
| | - Kelsey Keith
- The Coriell Institute for Medical Research, Camden, New Jersey, USA
| | | | | | - Jozef Madzo
- The Coriell Institute for Medical Research, Camden, New Jersey, USA
| | | | | | - Benjamin Gewurz
- Division of Infectious Diseases, Brigham & Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Italo Tempera
- The Wistar Institute, Philadelphia, Pennsylvania, USA
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4
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Caruso LB, Maestri D, Tempera I. Three-Dimensional Chromatin Structure of the EBV Genome: A Crucial Factor in Viral Infection. Viruses 2023; 15:1088. [PMID: 37243174 PMCID: PMC10222312 DOI: 10.3390/v15051088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/19/2023] [Accepted: 04/27/2023] [Indexed: 05/28/2023] Open
Abstract
Epstein-Barr Virus (EBV) is a human gamma-herpesvirus that is widespread worldwide. To this day, about 200,000 cancer cases per year are attributed to EBV infection. EBV is capable of infecting both B cells and epithelial cells. Upon entry, viral DNA reaches the nucleus and undergoes a process of circularization and chromatinization and establishes a latent lifelong infection in host cells. There are different types of latency all characterized by different expressions of latent viral genes correlated with a different three-dimensional architecture of the viral genome. There are multiple factors involved in the regulation and maintenance of this three-dimensional organization, such as CTCF, PARP1, MYC and Nuclear Lamina, emphasizing its central role in latency maintenance.
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Affiliation(s)
| | - Davide Maestri
- The Wistar Institute, Philadelphia, PA 19104, USA; (L.B.C.); (D.M.)
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Italo Tempera
- The Wistar Institute, Philadelphia, PA 19104, USA; (L.B.C.); (D.M.)
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5
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Lee SH, Kim KD, Cho M, Huh S, An SH, Seo D, Kang K, Lee M, Tanizawa H, Jung I, Cho H, Kang H. Characterization of a new CCCTC-binding factor binding site as a dual regulator of Epstein-Barr virus latent infection. PLoS Pathog 2023; 19:e1011078. [PMID: 36696451 PMCID: PMC9876287 DOI: 10.1371/journal.ppat.1011078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 12/15/2022] [Indexed: 01/26/2023] Open
Abstract
Distinct viral gene expression characterizes Epstein-Barr virus (EBV) infection in EBV-producing marmoset B-cell (B95-8) and EBV-associated gastric carcinoma (SNU719) cell lines. CCCTC-binding factor (CTCF) is a structural chromatin factor that coordinates chromatin interactions in the EBV genome. Chromatin immunoprecipitation followed by sequencing against CTCF revealed 16 CTCF binding sites in the B95-8 and SNU719 EBV genomes. The biological function of one CTCF binding site (S13 locus) located on the BamHI A right transcript (BART) miRNA promoter was elucidated experimentally. Microscale thermophoresis assay showed that CTCF binds more readily to the stable form than the mutant form of the S13 locus. EBV BART miRNA clusters encode 22 miRNAs, whose roles are implicated in EBV-related cancer pathogenesis. The B95-8 EBV genome lacks a 11.8-kb EcoRI C fragment, whereas the SNU719 EBV genome is full-length. ChIP-PCR assay revealed that CTCF, RNA polymerase II, H3K4me3 histone, and H3K9me3 histone were more enriched at S13 and S16 (167-kb) loci in B95-8 than in the SNU719 EBV genome. 4C-Seq and 3C-PCR assays using B95-8 and SNU719 cells showed that the S13 locus was associated with overall EBV genomic loci including 3-kb and 167-kb region in both EBV genomes. We generated mutations in the S13 locus in bacmids with or without the 11.8-kb BART transcript unit (BART(+/-)). The S13 mutation upregulated BART miRNA expression, weakened EBV latency, and reduced EBV infectivity in the presence of EcoRI C fragment. Another 3C-PCR assay using four types of BART(+/-)·S13(wild-type(Wt)/mutant(Mt)) HEK293-EBV cells revealed that the S13 mutation decreased DNA associations between the 167-kb region and 3-kb in the EBV genome. Based on these results, CTCF bound to the S13 locus along with the 11.8-kb EcoRI C fragment is suggested to form an EBV 3-dimensional DNA loop for coordinated EBV BART miRNA expression and infectivity.
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Affiliation(s)
- Sun Hee Lee
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
| | - Kyoung-Dong Kim
- Department of Systems Biotechnology, Chung-Ang University, Anseong, Korea
| | - Miyeon Cho
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
| | - Sora Huh
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
| | - Seong Ho An
- Department of Systems Biotechnology, Chung-Ang University, Anseong, Korea
| | - Donghyun Seo
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
| | - Kyuhyun Kang
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
| | - Minhee Lee
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
| | - Hideki Tanizawa
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Inuk Jung
- Department of Computer Science and Engineering, Kyungpook National University, Daegu, Korea
| | - Hyosun Cho
- Duksung Innovative Drug Center, College of Pharmacy, Duksung Women’s University, Seoul, Korea
- * E-mail: (HC); (HK)
| | - Hyojeung Kang
- College of Pharmacy, Vessel-Organ Interaction Research Center, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea
- * E-mail: (HC); (HK)
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6
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Friedman MJ, Lee H, Kwon YC, Oh S. Dynamics of Viral and Host 3D Genome Structure upon Infection. J Microbiol Biotechnol 2022; 32:1515-1526. [PMID: 36398441 PMCID: PMC9843816 DOI: 10.4014/jmb.2208.08020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/15/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022]
Abstract
Eukaryotic chromatin is highly organized in the 3D nuclear space and dynamically regulated in response to environmental stimuli. This genomic organization is arranged in a hierarchical fashion to support various cellular functions, including transcriptional regulation of gene expression. Like other host cellular mechanisms, viral pathogens utilize and modulate host chromatin architecture and its regulatory machinery to control features of their life cycle, such as lytic versus latent status. Combined with previous research focusing on individual loci, recent global genomic studies employing conformational assays coupled with high-throughput sequencing technology have informed models for host and, in some cases, viral 3D chromosomal structure re-organization during infection and the contribution of these alterations to virus-mediated diseases. Here, we review recent discoveries and progress in host and viral chromatin structural dynamics during infection, focusing on a subset of DNA (human herpesviruses and HPV) as well as RNA (HIV, influenza virus and SARS-CoV-2) viruses. An understanding of how host and viral genomic structure affect gene expression in both contexts and ultimately viral pathogenesis can facilitate the development of novel therapeutic strategies.
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Affiliation(s)
- Meyer J. Friedman
- Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Haram Lee
- College of Pharmacy, Korea University, Sejong 30019, Republic of Korea
| | - Young-Chan Kwon
- Center for Convergent Research of Emerging Virus Infections, Korean Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Soohwan Oh
- College of Pharmacy, Korea University, Sejong 30019, Republic of Korea
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7
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Human Cytomegalovirus Utilizes Multiple Viral Proteins to Regulate the Basement Membrane Protein Nidogen 1. J Virol 2022; 96:e0133622. [PMID: 36218358 PMCID: PMC9599421 DOI: 10.1128/jvi.01336-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nidogen 1 (NID1) is an important basement membrane protein secreted by many cell types. We previously found that human cytomegalovirus (HCMV) infection rapidly induced chromosome 1 breaks and that the basement membrane protein NID1, encoded near the 1q42 break site, was downregulated. We have now determined that the specific breaks in and of themselves did not regulate NID1, rather interactions between several viral proteins and the cellular machinery and DNA regulated NID1. We screened a battery of viral proteins present by 24 hours postinfection (hpi) when regulation was induced, including components of the incoming virion and immediate early (IE) proteins. Adenovirus (Ad) delivery of the tegument proteins pp71 and UL35 and the IE protein IE1 influenced steady-state (ss) NID1 levels. IE1's mechanism of regulation was unclear, while UL35 influenced proteasomal regulation of ss NID1. Real-time quantitative PCR (RT-qPCR) experiments determined that pp71 downregulated NID1 transcription. Surprisingly, WF28-71, a fibroblast clone that expresses minute quantities of pp71, suppressed NID1 transcription as efficiently as HCMV infection, resulting in the near absence of ss NID1. Sequence analysis of the region surrounding the 1q42 break sites and NID1 promoter revealed CCCTC-binding factor (CTCF) binding sites. Chromatin immunoprecipitation experiments determined that pp71 and CTCF were both bound at these two sites during HCMV infection. Expression of pp71 alone replicated this binding. Binding was observed as early as 1 hpi, and colocalization of pp71 and CTCF occurred as quickly as 15 min postinfection (pi) in infected cell nuclei. In fibroblasts where CTCF was knocked down, Adpp71 infection did not decrease NID1 transcription nor ss NID1 protein levels. Our results emphasize another aspect of pp71 activity during infection and identify this viral protein as a key contributor to HCMV's efforts to eliminate NID1. Further, we show, for the first time, direct interaction between pp71 and the cellular genome. IMPORTANCE We have found that human cytomegalovirus (HCMV) utilizes multiple viral proteins in multiple pathways to regulate a ubiquitous cellular basement membrane protein, nidogen-1 (NID1). The extent of the resources and the redundant methods that the virus has evolved to affect this control strongly suggest that its removal provides a life cycle advantage to HCMV. Our discoveries that one of the proteins that HCMV uses to control NID1, pp71, binds directly to the cellular DNA and can exert control when present in vanishingly small quantities may have broad implications in a wide range of infection scenarios. Dysregulation of NID1 in an immunocompetent host is not known to manifest complications during infection; however, in the naive immune system of a developing fetus, disruption of this developmentally critical protein could initiate catastrophic HCMV-induced birth defects.
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8
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The Epstein-Barr Virus Enhancer Interaction Landscapes in Virus-Associated Cancer Cell Lines. J Virol 2022; 96:e0073922. [PMID: 36094314 PMCID: PMC9517713 DOI: 10.1128/jvi.00739-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) persists in human cells as episomes. EBV episomes are chromatinized and their 3D conformation varies greatly in cells expressing different latency genes. We used HiChIP, an assay which combines genome-wide chromatin conformation capture followed by deep sequencing (Hi-C) and chromatin immunoprecipitation (ChIP), to interrogate the EBV episome 3D conformation in different cancer cell lines. In an EBV-transformed lymphoblastoid cell line (LCL) GM12878 expressing type III EBV latency genes, abundant genomic interactions were identified by H3K27ac HiChIP. A strong enhancer was located near the BILF2 gene and looped to multiple genes around BALFs loci. Perturbation of the BILF2 enhancer by CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa) altered the expression of BILF2 enhancer-linked genes, including BARF0 and BALF2, suggesting that this enhancer regulates the expression of linked genes. H3K27ac ChIP followed by deep sequencing (ChIP-seq) identified several strong EBV enhancers in T/NK (natural killer) lymphoma cells that express type II EBV latency genes. Extensive intragenomic interactions were also found which linked enhancers to target genes. A strong enhancer at BILF2 also looped to the BALF loci. CRISPRi also validated the functional connection between BILF2 enhancer and BARF1 gene. In contrast, H3K27ac HiChIP found significantly fewer intragenomic interactions in type I EBV latency gene-expressing primary effusion lymphoma (PEL) cell lines. These data provided new insight into the regulation of EBV latency gene expression in different EBV-associated tumors. IMPORTANCE EBV is the first human DNA tumor virus identified, discovered over 50 years ago. EBV causes ~200,000 cases of various cancers each year. EBV-encoded oncogenes, noncoding RNAs, and microRNAs (miRNAs) can promote cell growth and survival and suppress senescence. Regulation of EBV gene expression is very complex. The viral C promoter regulates the expression of all EBV nuclear antigens (EBNAs), some of which are very far away from the C promoter. Another way by which the virus activates remote gene expression is through DNA looping. In this study, we describe the viral genome looping patterns in various EBV-associated cancer cell lines and identify important EBV enhancers in these cells. This study also identified novel opportunities to perturb and eventually control EBV gene expression in these cancer cells.
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9
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Varghese CS, Parish JL, Ferguson J. Lying low-chromatin insulation in persistent DNA virus infection. Curr Opin Virol 2022; 55:101257. [PMID: 35998396 DOI: 10.1016/j.coviro.2022.101257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/08/2022] [Accepted: 07/28/2022] [Indexed: 11/03/2022]
Abstract
Persistent virus infections are achieved when the intricate balance of virus replication, host-cell division and successful immune evasion is met. The genomes of persistent DNA viruses are either maintained as extrachromosomal episomes or can integrate into the host genome. Common to both these strategies of persistence is the chromatinisation of viral DNA by cellular histones which, like host DNA, are subject to epigenetic modification. Epigenetic repression of viral genes required for lytic replication occurs, while genes required for latent or persistent infection are maintained in an active chromatin state. Viruses utilise host-cell chromatin insulators, which function to maintain epigenetic boundaries and enforce this strict transcriptional programme. Here, we review insulator protein function in virus transcription control, focussing on CCCTC-binding factor (CTCF) and cofactors. We describe CTCF-dependent activities in virus transcription regulation through epigenetic and promoter-enhancer insulation, three-dimensional chromatin looping and manipulation of transcript splicing.
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Affiliation(s)
- Christy S Varghese
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, B15 2TT, UK
| | - Joanna L Parish
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, B15 2TT, UK.
| | - Jack Ferguson
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, B15 2TT, UK
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10
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Morgan SM, Tanizawa H, Caruso LB, Hulse M, Kossenkov A, Madzo J, Keith K, Tan Y, Boyle S, Lieberman PM, Tempera I. The three-dimensional structure of Epstein-Barr virus genome varies by latency type and is regulated by PARP1 enzymatic activity. Nat Commun 2022; 13:187. [PMID: 35039491 PMCID: PMC8764100 DOI: 10.1038/s41467-021-27894-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/21/2021] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV) persists in human B-cells by maintaining its chromatinized episomes within the nucleus. We have previously shown that cellular factor Poly [ADP-ribose] polymerase 1 (PARP1) binds the EBV genome, stabilizes CTCF binding at specific loci, and that PARP1 enzymatic activity correlates with maintaining a transcriptionally active latency program. To better understand PARP1's role in regulating EBV latency, here we functionally characterize the effect of PARP enzymatic inhibition on episomal structure through in situ HiC mapping, generating a complete 3D structure of the EBV genome. We also map intragenomic contact changes after PARP inhibition to global binding of chromatin looping factors CTCF and cohesin across the EBV genome. We find that PARP inhibition leads to fewer total unique intragenomic interactions within the EBV episome, yet new chromatin loops distinct from the untreated episome are also formed. This study also illustrates that PARP inhibition alters gene expression at the regions where chromatin looping is most effected. We observe that PARP1 inhibition does not alter cohesin binding sites but does increase its frequency of binding at those sites. Taken together, these findings demonstrate that PARP has an essential role in regulating global EBV chromatin structure and latent gene expression.
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Affiliation(s)
- Sarah M Morgan
- The Wistar Institute, Philadelphia, PA, USA
- Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | | | | | - Michael Hulse
- Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | | | - Jozef Madzo
- The Coriell Institute for Medical Research, Camden, NJ, USA
| | - Kelsey Keith
- The Coriell Institute for Medical Research, Camden, NJ, USA
| | - Yinfei Tan
- Fox Chase Cancer Center, Philadelphia, PA, USA
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11
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Abstract
Among all of the known biological carcinogens, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are two of the classical oncogenic herpesviruses known to induce the oncogenic phenotype. Many studies have revealed important functions related to epigenetic alterations of the EBV and KSHV genomes that mediate oncogenesis, but the detailed mechanisms are not fully understood. It is also challenging to fully describe the critical cellular events that drive oncogenesis as well as a comprehensive map of the molecular contributors. This review introduces the roles of epigenetic modifications of these viral genomes, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA expression, and elucidates potential strategies utilized for inducing oncogenesis by these human gammaherpesviruses.
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Affiliation(s)
- Yonggang Pei
- Departments of Otorhinolaryngology-Head and Neck Surgery and Microbiology, Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Josiah Hiu-Yuen Wong
- Departments of Otorhinolaryngology-Head and Neck Surgery and Microbiology, Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Erle S Robertson
- Departments of Otorhinolaryngology-Head and Neck Surgery and Microbiology, Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
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12
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Majumder K, Morales AJ. Utilization of Host Cell Chromosome Conformation by Viral Pathogens: Knowing When to Hold and When to Fold. Front Immunol 2021; 12:633762. [PMID: 33841414 PMCID: PMC8027251 DOI: 10.3389/fimmu.2021.633762] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/09/2021] [Indexed: 11/13/2022] Open
Abstract
Though viruses have their own genomes, many depend on the nuclear environment of their hosts for replication and survival. A substantial body of work has therefore been devoted to understanding how viral and eukaryotic genomes interact. Recent advances in chromosome conformation capture technologies have provided unprecedented opportunities to visualize how mammalian genomes are organized and, by extension, how packaging of nuclear DNA impacts cellular processes. Recent studies have indicated that some viruses, upon entry into host cell nuclei, produce factors that alter host chromatin topology, and thus, impact the 3D organization of the host genome. Additionally, a variety of distinct viruses utilize host genome architectural factors to advance various aspects of their life cycles. Indeed, human gammaherpesviruses, known for establishing long-term reservoirs of latent infection in B lymphocytes, utilize 3D principles of genome folding to package their DNA and establish latency in host cells. This manipulation of host epigenetic machinery by latent viral genomes is etiologically linked to the onset of B cell oncogenesis. Small DNA viruses, by contrast, are tethered to distinct cellular sites that support virus expression and replication. Here, we briefly review the recent findings on how viruses and host genomes spatially communicate, and how this impacts virus-induced pathology.
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Affiliation(s)
- Kinjal Majumder
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, Human Cancer Virology Program, University of Wisconsin Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Abigail J Morales
- Department of Medical Laboratory Sciences, Hunter College of the City University of New York, New York, NY, United States
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13
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Jefferys SR, Burgos SD, Peterson JJ, Selitsky SR, Turner AMW, James LI, Tsai YH, Coffey AR, Margolis DM, Parker J, Browne EP. Epigenomic characterization of latent HIV infection identifies latency regulating transcription factors. PLoS Pathog 2021; 17:e1009346. [PMID: 33635929 PMCID: PMC7946360 DOI: 10.1371/journal.ppat.1009346] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 03/10/2021] [Accepted: 01/29/2021] [Indexed: 12/12/2022] Open
Abstract
Transcriptional silencing of HIV in CD4 T cells generates a reservoir of latently infected cells that can reseed infection after interruption of therapy. As such, these cells represent the principal barrier to curing HIV infection, but little is known about their characteristics. To further our understanding of the molecular mechanisms of latency, we characterized a primary cell model of HIV latency in which infected cells adopt heterogeneous transcriptional fates. In this model, we observed that latency is a stable, heritable state that is transmitted through cell division. Using Assay of Transposon-Accessible Chromatin sequencing (ATACseq) we found that latently infected cells exhibit greatly reduced proviral accessibility, indicating the presence of chromatin-based structural barriers to viral gene expression. By quantifying the activity of host cell transcription factors, we observe elevated activity of Forkhead and Kruppel-like factor transcription factors (TFs), and reduced activity of AP-1, RUNX and GATA TFs in latently infected cells. Interestingly, latency reversing agents with different mechanisms of action caused distinct patterns of chromatin reopening across the provirus. We observe that binding sites for the chromatin insulator CTCF are highly enriched in the differentially open chromatin of infected CD4 T cells. Furthermore, depletion of CTCF inhibited HIV latency, identifying this factor as playing a key role in the initiation or enforcement of latency. These data indicate that HIV latency develops preferentially in cells with a distinct pattern of TF activity that promotes a closed proviral structure and inhibits viral gene expression. Furthermore, these findings identify CTCF as a novel regulator of HIV latency. HIV is able to persist during antiviral therapy by entering a state of viral latency, in which viral gene expression is greatly reduced. These latently infected cells can re-seed infection if therapy is interrupted, and thus represent a major obstacle to an HIV cure. Identifying the mechanisms that lead to this state will help to identify strategies to block or eliminate HIV latency, leading to a cure for infection. By observing HIV gene expression in infected CD4 T cells, we isolated cells in which HIV has entered latency and identified characteristics that distinguish them from cells with active viral replication. We found that latently infected cells have elevated activity of specific transcription factors including Forkhead TFs and Kruppel-like factors. We also identify CTCF, a protein responsible for mediating insulation of genome domains from each other, as being required for the establishment of HIV latency. Developing agents to target these factors may lead to new strategies to eliminate the HIV reservoir.
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Affiliation(s)
- Stuart R. Jefferys
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Samuel D. Burgos
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jackson J. Peterson
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sara R. Selitsky
- Lineberger Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Anne-Marie W. Turner
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Lindsey I. James
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Yi-Hsuan Tsai
- Lineberger Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Alisha R. Coffey
- Lineberger Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - David M. Margolis
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Joel Parker
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Edward P. Browne
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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14
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Boftsi M, Majumder K, Burger LR, Pintel DJ. Binding of CCCTC-Binding Factor (CTCF) to the Minute Virus of Mice Genome Is Important for Proper Processing of Viral P4-Generated Pre-mRNAs. Viruses 2020; 12:E1368. [PMID: 33266080 PMCID: PMC7760686 DOI: 10.3390/v12121368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/23/2020] [Accepted: 11/25/2020] [Indexed: 12/17/2022] Open
Abstract
Specific chromatin immunoprecipitation of salt-fractionated infected cell extracts has demonstrated that the CCCTC-binding factor (CTCF), a highly conserved, 11-zinc-finger DNA-binding protein with known roles in cellular and viral genome organization and gene expression, specifically binds the genome of Minute Virus of Mice (MVM). Mutations that diminish binding of CTCF to MVM affect processing of the P4-generated pre-mRNAs. These RNAs are spliced less efficiently to generate the R1 mRNA, and definition of the NS2-specific exon upstream of the small intron is reduced, leading to relatively less R2 and the generation of a novel exon-skipped product. These results suggest a model in which CTCF is required for proper engagement of the spliceosome at the MVM small intron and for the first steps of processing of the P4-generated pre-mRNA.
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Affiliation(s)
- Maria Boftsi
- Pathobiology Area Graduate Program, Christopher S. Bond Life Sciences Center, School of Medicine, University of Missouri-Columbia, Columbia, MO 65211, USA;
| | - Kinjal Majumder
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri-Columbia, Columbia, MO 65211, USA; (K.M.); (L.R.B.)
| | - Lisa R. Burger
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri-Columbia, Columbia, MO 65211, USA; (K.M.); (L.R.B.)
| | - David J. Pintel
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri-Columbia, Columbia, MO 65211, USA; (K.M.); (L.R.B.)
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15
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Tsunemine H, Zushi Y, Sasaki M, Nishikawa Y, Tamura A, Aoyama Y, Kodaka T, Itoh T, Takahashi T. Gamma heavy chain disease (γ-HCD) as iatrogenic immunodeficiency- associated lymphoproliferative disorder: Possible emergent subtype of rheumatoid arthritis-associated γ-HCD. J Clin Exp Hematop 2020; 59:196-201. [PMID: 31866621 PMCID: PMC6954170 DOI: 10.3960/jslrt.19025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Gamma heavy chain disease (γ-HCD) is a rare B-cell neoplasm that produces a truncated immunoglobulin γ-heavy chain lacking the light chain. The clinical features of γ-HCD are heterogeneous, resembling different types of B-cell lymphomas. Although rheumatoid arthritis (RA) is one of the common underlying diseases of γ-HCD, the therapeutic modality for RA has changed greatly in recent years; therefore, γ-HCD as iatrogenic immunodeficiency-associated lymphoproliferative disorder (LPD) should be taken into consideration. Here, we report such a γ-HCD case. A 69-year-old female was admitted because of fever, multiple lymph node swelling in the abdominal cavity, and peritoneal effusion. She had been treated using methotrexate for RA for 14 years, and using infliximab and adalimumab for Crohn’s disease for one year. The serum concentration of IgG was 3,525 mg/dL, which was revealed to be monoclonal IgG lacking the light chain by rocket immunoselection assay. CD19+/CD20-/smκ−/smλ− large abnormal lymphocytes were observed in the peritoneal fluid, which were demonstrated to be clonal B-cells by PCR examination. Discontinuation of methotrexate did not improve her condition and she died of pneumonia. Many abnormal lymphocytes positive for IgG and EBER but negative for the light chain were found on immunohistological examination of necropsy specimens from the spleen and bone marrow.
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16
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Burley M, Roberts S, Parish JL. Epigenetic regulation of human papillomavirus transcription in the productive virus life cycle. Semin Immunopathol 2020; 42:159-171. [PMID: 31919577 PMCID: PMC7174255 DOI: 10.1007/s00281-019-00773-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 11/08/2019] [Indexed: 12/13/2022]
Abstract
Human papillomaviruses (HPV) are a large family of viruses which contain a circular, double-stranded DNA genome of approximately 8000 base pairs. The viral DNA is chromatinized by the recruitment of cellular histones which are subject to host cell-mediated post-translational epigenetic modification recognized as an important mechanism of virus transcription regulation. The HPV life cycle is dependent on the terminal differentiation of the target cell within epithelia-the keratinocyte. The virus life cycle begins in the undifferentiated basal compartment of epithelia where the viral chromatin is maintained in an epigenetically repressed state, stabilized by distal chromatin interactions between the viral enhancer and early gene region. Migration of the infected keratinocyte towards the surface of the epithelium induces cellular differentiation which disrupts chromatin looping and stimulates epigenetic remodelling of the viral chromatin. These epigenetic changes result in enhanced virus transcription and activation of the virus late promoter facilitating transcription of the viral capsid proteins. In this review article, we discuss the complexity of virus- and host-cell-mediated epigenetic regulation of virus transcription with a specific focus on differentiation-dependent remodelling of viral chromatin during the HPV life cycle.
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Affiliation(s)
- Megan Burley
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Sciences, University of Birmingham, B152TT, Birmingham, UK
| | - Sally Roberts
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Sciences, University of Birmingham, B152TT, Birmingham, UK
| | - Joanna L Parish
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Sciences, University of Birmingham, B152TT, Birmingham, UK.
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17
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Li D, Mosbruger T, Verma D, Swaminathan S. Complex Interactions between Cohesin and CTCF in Regulation of Kaposi's Sarcoma-Associated Herpesvirus Lytic Transcription. J Virol 2020; 94:e01279-19. [PMID: 31666380 PMCID: PMC6955261 DOI: 10.1128/jvi.01279-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/18/2019] [Indexed: 12/18/2022] Open
Abstract
CTCF and the cohesin complex modify chromatin by binding to DNA and interacting with each other and with other cellular proteins. Both proteins regulate transcription by a variety of local effects on transcription and by long-range topological effects. CTCF and cohesin also bind to herpesvirus genomes at specific sites and regulate viral transcription during latent and lytic cycles of replication. Kaposi's sarcoma-associated herpesvirus (KSHV) transcription is regulated by CTCF and cohesin, with both proteins previously reported to act as restrictive factors for lytic cycle transcription and virion production. In this study, we examined the interdependence of CTCF and cohesin binding to the KSHV genome. Chromatin immunoprecipitation sequencing (ChIP-seq) analyses revealed that cohesin binding to the KSHV genome is highly CTCF dependent, whereas CTCF binding does not require cohesin. Furthermore, depletion of CTCF leads to the almost complete dissociation of cohesin from sites at which they colocalize. Thus, previous studies that examined the effects of CTCF depletion actually represent the concomitant depletion of both CTCF and cohesin components. Analysis of the effects of single and combined depletion indicates that CTCF primarily activates KSHV lytic transcription, whereas cohesin has primarily inhibitory effects. Furthermore, CTCF or cohesin depletion was found to have regulatory effects on cellular gene expression relevant for the control of viral infection, with both proteins potentially facilitating the expression of multiple genes important in the innate immune response to viruses. Thus, CTCF and cohesin have both positive and negative effects on KSHV lytic replication as well as effects on the host cell that enhance antiviral defenses.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is causally linked to Kaposi's sarcoma and several lymphoproliferative diseases. KSHV, like other herpesviruses, intermittently reactivates from latency and enters a lytic cycle in which numerous lytic mRNAs and proteins are produced, culminating in infectious virion production. These lytic proteins may also contribute to tumorigenesis. Reactivation from latency is controlled by processes that restrict or activate the transcription of KSHV lytic genes. KSHV gene expression is modulated by binding of the host cell proteins CTCF and cohesin complex to the KSHV genome. These proteins bind to and modulate the conformation of chromatin, thereby regulating transcription. We have analyzed the interdependence of binding of CTCF and cohesin and demonstrate that while CTCF is required for cohesin binding to KSHV, they have very distinct effects, with cohesin primarily restricting KSHV lytic transcription. Furthermore, we show that cohesin and CTCF also exert effects on the host cell that promote antiviral defenses.
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Affiliation(s)
- Dajiang Li
- Division of Infectious Diseases, Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Tim Mosbruger
- Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Dinesh Verma
- Division of Infectious Diseases, Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Sankar Swaminathan
- Division of Infectious Diseases, Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
- George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, USA
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18
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The Role of PARPs in Inflammation-and Metabolic-Related Diseases: Molecular Mechanisms and Beyond. Cells 2019; 8:cells8091047. [PMID: 31500199 PMCID: PMC6770262 DOI: 10.3390/cells8091047] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 08/27/2019] [Accepted: 09/03/2019] [Indexed: 12/18/2022] Open
Abstract
Poly(ADP-ribosyl)ation (PARylation) is an essential post-translational modification catalyzed by poly(ADP-ribose) polymerase (PARP) enzymes. Poly(ADP-ribose) polymerase 1 (PARP1) is a well-characterized member of the PARP family. PARP1 plays a crucial role in multiple biological processes and PARP1 activation contributes to the development of various inflammatory and malignant disorders, including lung inflammatory disorders, cardiovascular disease, ovarian cancer, breast cancer, and diabetes. In this review, we will focus on the role and molecular mechanisms of PARPs enzymes in inflammation- and metabolic-related diseases. Specifically, we discuss the molecular mechanisms and signaling pathways that PARP1 is associated with in the regulation of pathogenesis. Recently, increasing evidence suggests that PARP inhibition is a promising strategy for intervention of some diseases. Thus, our in-depth understanding of the mechanism of how PARPs are activated and how their signaling downstream effecters can provide more potential therapeutic targets for the treatment of the related diseases in the future is crucial.
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19
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Ke Y, Zhang J, Lv X, Zeng X, Ba X. Novel insights into PARPs in gene expression: regulation of RNA metabolism. Cell Mol Life Sci 2019; 76:3283-3299. [PMID: 31055645 PMCID: PMC6697709 DOI: 10.1007/s00018-019-03120-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 04/13/2019] [Accepted: 04/29/2019] [Indexed: 12/15/2022]
Abstract
Poly(ADP-ribosyl)ation (PARylation) is an important post-translational modification in which an ADP-ribose group is transferred to the target protein by poly(ADP-riboses) polymerases (PARPs). Since the discovery of poly-ADP-ribose (PAR) 50 years ago, its roles in cellular processes have been extensively explored. Although research initially focused on the functions of PAR and PARPs in DNA damage detection and repair, our understanding of the roles of PARPs in various nuclear and cytoplasmic processes, particularly in gene expression, has increased significantly. In this review, we discuss the current advances in understanding the roles of PARylation with a particular emphasis in gene expression through RNA biogenesis and processing. In addition to updating PARP's significance in transcriptional regulation, we specifically focus on how PARPs and PARylation affect gene expression, especially inflammation-related genes, at the post-transcriptional levels by modulating RNA processing and degrading. Increasing evidence suggests that PARP inhibition is a promising treatment for inflammation-related diseases besides conventional chemotherapy for cancer.
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Affiliation(s)
- Yueshuang Ke
- The Key Laboratory of Molecular Epigenetics of the Ministry of Education, Institute of Genetics and Cytology, School of Life Science, Northeast Normal University, Changchun, 130024, Jilin, China
| | - Jing Zhang
- The Key Laboratory of Molecular Epigenetics of the Ministry of Education, Institute of Genetics and Cytology, School of Life Science, Northeast Normal University, Changchun, 130024, Jilin, China
| | - Xueping Lv
- The Key Laboratory of Molecular Epigenetics of the Ministry of Education, Institute of Genetics and Cytology, School of Life Science, Northeast Normal University, Changchun, 130024, Jilin, China
| | - Xianlu Zeng
- The Key Laboratory of Molecular Epigenetics of the Ministry of Education, Institute of Genetics and Cytology, School of Life Science, Northeast Normal University, Changchun, 130024, Jilin, China
| | - Xueqing Ba
- The Key Laboratory of Molecular Epigenetics of the Ministry of Education, Institute of Genetics and Cytology, School of Life Science, Northeast Normal University, Changchun, 130024, Jilin, China.
- College of Life and Environmental Science, Wenzhou University, Wenzhou, 325035, China.
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20
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Ando M, Saito Y, Xu G, Bui NQ, Medetgul-Ernar K, Pu M, Fisch K, Ren S, Sakai A, Fukusumi T, Liu C, Haft S, Pang J, Mark A, Gaykalova DA, Guo T, Favorov AV, Yegnasubramanian S, Fertig EJ, Ha P, Tamayo P, Yamasoba T, Ideker T, Messer K, Califano JA. Chromatin dysregulation and DNA methylation at transcription start sites associated with transcriptional repression in cancers. Nat Commun 2019; 10:2188. [PMID: 31097695 PMCID: PMC6522544 DOI: 10.1038/s41467-019-09937-w] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 04/09/2019] [Indexed: 02/08/2023] Open
Abstract
Although promoter-associated CpG islands have been established as targets of DNA methylation changes in cancer, previous studies suggest that epigenetic dysregulation outside the promoter region may be more closely associated with transcriptional changes. Here we examine DNA methylation, chromatin marks, and transcriptional alterations to define the relationship between transcriptional modulation and spatial changes in chromatin structure. Using human papillomavirus-related oropharyngeal carcinoma as a model, we show aberrant enrichment of repressive H3K9me3 at the transcriptional start site (TSS) with methylation-associated, tumor-specific gene silencing. Further analysis identifies a hypermethylated subtype which shows a functional convergence on MYC targets and association with CREBBP/EP300 mutation. The tumor-specific shift to transcriptional repression associated with DNA methylation at TSSs was confirmed in multiple tumor types. Our data may show a common underlying epigenetic dysregulation in cancer associated with broad enrichment of repressive chromatin marks and aberrant DNA hypermethylation at TSSs in combination with MYC network activation.
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Affiliation(s)
- Mizuo Ando
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
- Department of Otolaryngology - Head and Neck Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Yuki Saito
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
- Department of Otolaryngology - Head and Neck Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Guorong Xu
- Department of Medicine, Center for Computational Biology and Bioinformatics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Nam Q Bui
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
- Department of Medicine (Oncology), Stanford University School of Medicine, 875 Blake Wilbur Dr, Palo Alto, CA, 94304, USA
| | - Kate Medetgul-Ernar
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Minya Pu
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Kathleen Fisch
- Department of Medicine, Center for Computational Biology and Bioinformatics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Shuling Ren
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Akihiro Sakai
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Takahito Fukusumi
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Chao Liu
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Sunny Haft
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - John Pang
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Adam Mark
- Department of Medicine, Center for Computational Biology and Bioinformatics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Daria A Gaykalova
- Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University School of Medicine, 601 N Caroline St, Baltimore, MD, 21287, USA
| | - Theresa Guo
- Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University School of Medicine, 601 N Caroline St, Baltimore, MD, 21287, USA
| | - Alexander V Favorov
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 401 N Broadway, Baltimore, MD, 21231, USA
- Laboratory of Systems Biology and Computational Genetics, Vavilov Institute of General Genetics, Russian Academy of Sciences, Gubkina str. 3, Moscow, 119333, Russia
| | - Srinivasan Yegnasubramanian
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 401 N Broadway, Baltimore, MD, 21231, USA
| | - Elana J Fertig
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 401 N Broadway, Baltimore, MD, 21231, USA
| | - Patrick Ha
- Department of Otolaryngology - Head and Neck Surgery, University of California San Francisco, 2380 Sutter St, San Francisco, CA, 94115, USA
| | - Pablo Tamayo
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Tatsuya Yamasoba
- Department of Otolaryngology - Head and Neck Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Trey Ideker
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Karen Messer
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA
| | - Joseph A Califano
- Moores Cancer Center, University of California San Diego, 3855 Health Sciences Dr, La Jolla, CA, 92093, USA.
- Division of Otolaryngology - Head and Neck Surgery, Department of Surgery, University of California San Diego, 9300 Campus Point Drive, La Jolla, CA, 92037, USA.
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21
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Macaca arctoides gammaherpesvirus 1 (strain herpesvirus Macaca arctoides): virus sequence, phylogeny and characterisation of virus-transformed macaque and rabbit cell lines. Med Microbiol Immunol 2018; 208:109-129. [PMID: 30291474 DOI: 10.1007/s00430-018-0565-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/27/2018] [Indexed: 10/28/2022]
Abstract
Herpesvirus Macaca arctoides (HVMA) has the propensity to transform macaque lymphocytes to lymphoblastoid cells (MAL-1). Inoculation of rabbits with cell-free virus-containing supernatant resulted in the development of malignant lymphomas and allowed isolation of immortalised HVMA-transformed rabbit lymphocytes (HTRL). In this study, the HVMA genome sequence (approx. 167 kbp), its organisation, and novel aspects of virus latency are presented. Ninety-one open reading frames were identified, of which 86 were non-repetitive. HVMA was identified as a Lymphocryptovirus closely related to Epstein-Barr virus, suggesting the designation as 'Macaca arctoides gammaherpesvirus 1' (MarcGHV-1). In situ lysis gel and Southern blot hybridisation experiments revealed that the MAL-1 cell line contains episomal and linear DNA, whereas episomal DNA is predominantly present in HTRL. Integration of viral DNA into macaque and rabbit host cell genomes was demonstrated by fluorescence in situ hybridisation on chromosomal preparations. Analysis of next-generation sequencing data confirmed this finding. Approximately 400 read pairs represent the overlap between macaque and MarcGHV-1 DNA. Both, MAL-1 cells and HTRL show characteristics of a polyclonal tumour with B- and T-lymphocyte markers. Based on analysis of viral gene expression and immunohistochemistry, the persistence of MarcGHV-1 in MAL-1 cells resemble the latency type III, whereas the expression pattern observed in HTRL was more comparable with latency type II. There was no evidence of the presence of STLV-1 proviral DNA in MAL-1 and HTRL. Due to the similarity to EBV-mediated cell transformation, MarcGHV-1 expands the available in vitro models by simian and rabbit cell lines.
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22
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Pentland I, Campos-León K, Cotic M, Davies KJ, Wood CD, Groves IJ, Burley M, Coleman N, Stockton JD, Noyvert B, Beggs AD, West MJ, Roberts S, Parish JL. Disruption of CTCF-YY1-dependent looping of the human papillomavirus genome activates differentiation-induced viral oncogene transcription. PLoS Biol 2018; 16:e2005752. [PMID: 30359362 PMCID: PMC6219814 DOI: 10.1371/journal.pbio.2005752] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 11/06/2018] [Accepted: 10/12/2018] [Indexed: 11/19/2022] Open
Abstract
The complex life cycle of oncogenic human papillomavirus (HPV) initiates in undifferentiated basal epithelial keratinocytes where expression of the E6 and E7 oncogenes is restricted. Upon epithelial differentiation, E6/E7 transcription is increased through unknown mechanisms to drive cellular proliferation required to support virus replication. We report that the chromatin-organising CCCTC-binding factor (CTCF) promotes the formation of a chromatin loop in the HPV genome that epigenetically represses viral enhancer activity controlling E6/E7 expression. CTCF-dependent looping is dependent on the expression of the CTCF-associated Yin Yang 1 (YY1) transcription factor and polycomb repressor complex (PRC) recruitment, resulting in trimethylation of histone H3 at lysine 27. We show that viral oncogene up-regulation during cellular differentiation results from YY1 down-regulation, disruption of viral genome looping, and a loss of epigenetic repression of viral enhancer activity. Our data therefore reveal a key role for CTCF-YY1-dependent looping in the HPV life cycle and identify a regulatory mechanism that could be disrupted in HPV carcinogenesis.
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Affiliation(s)
- Ieisha Pentland
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Karen Campos-León
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Marius Cotic
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Kelli-Jo Davies
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - C. David Wood
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
| | - Ian J. Groves
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Megan Burley
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Nicholas Coleman
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Joanne D. Stockton
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Boris Noyvert
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Andrew D. Beggs
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Michelle J. West
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
| | - Sally Roberts
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Joanna L. Parish
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
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Guo J, Li N, Han J, Pei F, Wang T, Lu D, Jiang J. DNA recognition patterns of the multi-zinc-finger protein CTCF: a mutagenesis study. Acta Pharm Sin B 2018; 8:900-908. [PMID: 30505659 PMCID: PMC6251859 DOI: 10.1016/j.apsb.2018.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 06/04/2018] [Accepted: 06/28/2018] [Indexed: 12/17/2022] Open
Abstract
CCCTC-binding factor (CTCF) is a zinc-finger protein, serving an important part in the genome architecture as well as some biochemical processes. Over 70,000 CTCF binding DNA sites have been detected genome-wide, and most anchors of chromatin loops are demarcated with the CTCF binding. Various protein or RNA molecules interact with DNA-bound CTCF to conduct different biological functions, and potentially the interfaces between CTCF and its cofactors can be targets for drug development. Here we identify the effective region of CTCF in DNA recognition, which defines the exposed CTCF surface feature for the interaction of cofactors. While the zinc-finger region contributes the most in DNA association, its binding affinity varies based on different DNA sequences. To investigate the effectiveness of individual zinc-fingers, the key residues are mutated to inactivate the DNA binding ability, while the finger configuration and the spacing between fingers are preserved. The strategy is proved to be successful, while clear differences are observed in the DNA binding affinities among the 11 finger mutants and the result is consistent to previous studies in general. With the help of inactivated finger mutants, we identify the ineffective fingers and the dominant effective fingers, which form distinctive patterns on different DNA targets.
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PARP1 Stabilizes CTCF Binding and Chromatin Structure To Maintain Epstein-Barr Virus Latency Type. J Virol 2018; 92:JVI.00755-18. [PMID: 29976663 PMCID: PMC6146685 DOI: 10.1128/jvi.00755-18] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/26/2018] [Indexed: 12/14/2022] Open
Abstract
EBV is a human gammaherpesvirus that infects more than 95% of individuals worldwide. Upon infection, EBV circularizes as an episome and establishes a chronic, latent infection in B cells. In doing so, the virus utilizes host cell machinery to regulate and maintain the viral genome. In otherwise healthy individuals, EBV infection is typically nonpathological; however, latent infection is potentially oncogenic and is responsible for 1% of human cancers. During latent infection, EBV expresses specific sets of proteins according to the given latency type, each of which is associated with specific types of cancers. For example, type III latency, in which the virus expresses its full repertoire of latent proteins, is characteristic of AIDS-associated and posttransplant lymphomas associated with EBV infection. Understanding how viral latency type is regulated at the chromatin level may reveal potential targets for EBV-specific pharmacological intervention in EBV-associated cancers. Epstein Barr virus (EBV) is a potentially oncogenic gammaherpesvirus that establishes a chronic, latent infection in memory B cells. The EBV genome persists in infected host cells as a chromatinized episome and is subject to chromatin-mediated regulation. Binding of the host insulator protein CTCF to the EBV genome has an established role in maintaining viral latency type. CTCF is posttranslationally modified by the host enzyme PARP1. PARP1, or poly(ADP-ribose) polymerase 1, catalyzes the transfer of a poly(ADP-ribose) (PAR) moiety from NAD+ onto acceptor proteins, including itself, histone proteins, and CTCF. PARylation of CTCF by PARP1 can affect CTCF's insulator activity, DNA binding capacity, and ability to form chromatin loops. Both PARP1 and CTCF have been implicated in the regulation of EBV latency and lytic reactivation. Thus, we predicted that pharmacological inhibition with PARP1 inhibitors would affect EBV latency type through a chromatin-specific mechanism. Here, we show that PARP1 and CTCF colocalize at specific sites throughout the EBV genome and provide evidence to suggest that PARP1 acts to stabilize CTCF binding and maintain the open chromatin landscape at the active Cp promoter during type III latency. Further, PARP1 activity is important in maintaining latency type-specific viral gene expression. The data presented here provide a rationale for the use of PARP inhibitors in the treatment of EBV-associated cancers exhibiting type III latency and ultimately could contribute to an EBV-specific treatment strategy for AIDS-related or posttransplant lymphomas. IMPORTANCE EBV is a human gammaherpesvirus that infects more than 95% of individuals worldwide. Upon infection, EBV circularizes as an episome and establishes a chronic, latent infection in B cells. In doing so, the virus utilizes host cell machinery to regulate and maintain the viral genome. In otherwise healthy individuals, EBV infection is typically nonpathological; however, latent infection is potentially oncogenic and is responsible for 1% of human cancers. During latent infection, EBV expresses specific sets of proteins according to the given latency type, each of which is associated with specific types of cancers. For example, type III latency, in which the virus expresses its full repertoire of latent proteins, is characteristic of AIDS-associated and posttransplant lymphomas associated with EBV infection. Understanding how viral latency type is regulated at the chromatin level may reveal potential targets for EBV-specific pharmacological intervention in EBV-associated cancers.
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25
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Brooks WH. Viral Impact in Autoimmune Diseases: Expanding the "X Chromosome-Nucleolus Nexus" Hypothesis. Front Immunol 2017; 8:1657. [PMID: 29234321 PMCID: PMC5712313 DOI: 10.3389/fimmu.2017.01657] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 11/13/2017] [Indexed: 12/19/2022] Open
Abstract
Viruses are suspected of significant roles in autoimmune diseases but the mechanisms are unclear. We get some insight by considering demands a virus places on host cells. Viruses not only require production of their own proteins, RNA and/or DNA, but also production of additional cellular machinery, such as ribosomes, to handle the increased demands. Since the nucleolus is a major site of RNA processing and ribonucleoprotein assembly, nucleoli are targeted by viruses, directly when viral RNA and proteins enter the nucleolus and indirectly when viruses induce increased expression of cellular polyamine genes. Polyamines are at high levels in nucleoli to assist in RNA folding. The size and activity of nucleoli increase directly with increases in polyamines. Nucleolar expansion due to abnormal increases in polyamines could disrupt nearby chromatin, such as the inactive X chromosome, leading to expression of previously sequestered DNA. Sudden expression of a large concentration of Alu elements from the disrupted inactive X can compete with RNA transcripts containing intronic Alu sequences that normally maintain nucleolar structural integrity. Such disruption of nucleolar activity can lead to misfolded RNAs, misassembled ribonucleoprotein complexes, and fragmentation of the nucleolus. Many autoantigens in lupus are, at least transiently, components of the nucleolus. Considering these effects of viruses, the “X chromosome–nucleolus nexus” hypothesis, which proposed disruption of the inactive X by the nucleolus during stress, is now expanded here to propose subsequent disruption of the nucleolus by previously sequestered Alu elements, which can fragment the nucleolus, leading to generation of autoantigens.
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Affiliation(s)
- Wesley H Brooks
- Department of Chemistry, University of South Florida, Tampa, FL, United States
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26
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Kamranvar SA, Masucci MG. Regulation of Telomere Homeostasis during Epstein-Barr virus Infection and Immortalization. Viruses 2017; 9:v9080217. [PMID: 28792435 PMCID: PMC5580474 DOI: 10.3390/v9080217] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 12/11/2022] Open
Abstract
The acquisition of unlimited proliferative potential is dependent on the activation of mechanisms for telomere maintenance, which counteracts telomere shortening and the consequent triggering of the DNA damage response, cell cycle arrest, and apoptosis. The capacity of Epstein Barr virus (EBV) to infect B-lymphocytes in vitro and transform the infected cells into autonomously proliferating immortal cell lines underlies the association of this human gamma-herpesvirus with a broad variety of lymphoid and epithelial cell malignancies. Current evidence suggests that both telomerase-dependent and -independent pathways of telomere elongation are activated in the infected cells during the early and late phases of virus-induced immortalization. Here we review the interaction of EBV with different components of the telomere maintenance machinery and the mechanisms by which the virus regulates telomere homeostasis in proliferating cells. We also discuss how these viral strategies may contribute to malignant transformation.
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Affiliation(s)
- Siamak A Kamranvar
- Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, 751 23 Uppsala, Sweden.
| | - Maria G Masucci
- Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden.
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27
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Epstein-Barr Virus Rta-Mediated Accumulation of DNA Methylation Interferes with CTCF Binding in both Host and Viral Genomes. J Virol 2017; 91:JVI.00736-17. [PMID: 28490592 DOI: 10.1128/jvi.00736-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 05/02/2017] [Indexed: 12/18/2022] Open
Abstract
Rta, an Epstein-Barr virus (EBV) immediate-early protein, reactivates viral lytic replication that is closely associated with tumorigenesis. In previous studies, we demonstrated that in epithelial cells Rta efficiently induced cellular senescence, which is an irreversible G1 arrest likely to provide a favorable environment for productive replications of EBV and Kaposi's sarcoma-associated herpesvirus (KSHV). To restrict progression of the cell cycle, Rta simultaneously upregulates CDK inhibitors and downregulates MYC, CCND1, and JUN, among others. Rta has long been known as a potent transcriptional activator, thus its role in gene repression is unexpected. In silico analysis revealed that the promoter regions of MYC, CCND1, and JUN are common in (i) the presence of CpG islands, (ii) strong chromatin immunoprecipitation (ChIP) signals of CCCTC-binding factor (CTCF), and (iii) having at least one Rta binding site. By combining ChIP assays and DNA methylation analysis, here we provide evidence showing that Rta binding accumulated CpG methylation and decreased CTCF occupancy in the regulatory regions of MYC, CCND1, and JUN, which were associated with downregulated gene expression. Stable residence of CTCF in the viral latency and reactivation control regions is a hallmark of viral latency. Here, we observed that Rta-mediated decreased binding of CTCF in the viral genome is concurrent with virus reactivation. Via interfering with CTCF binding, in the host genome Rta can function as a transcriptional repressor for gene silencing, while in the viral genome Rta acts as an activator for lytic gene loci by removing a topological constraint established by CTCF.IMPORTANCE CTCF is a multifunctional protein that variously participates in gene expression and higher-order chromatin structure of the cellular and viral genomes. In certain loci of the genome, CTCF occupancy and DNA methylation are mutually exclusive. Here, we demonstrate that the Epstein-Barr virus (EBV) immediate-early protein, Rta, known to be a transcriptional activator, can also function as a transcriptional repressor. Via enriching CpG methylation and decreasing CTCF reloading, Rta binding efficiently shut down the expression of MYC, CCND1, and JUN, thus impeding cell cycle progression. Rta-mediated disruption of CTCF binding was also detected in the latency/reactivation control regions of the EBV genome, and this in turn led to viral lytic cycle progression. As emerging evidence indicates that a methylated EBV genome is a preferable substrate for EBV Zta, the other immediate-early protein, our results suggest a mechanistic link in understanding the molecular processes of viral latent-lytic switch.
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28
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Poole CJ, van Riggelen J. MYC-Master Regulator of the Cancer Epigenome and Transcriptome. Genes (Basel) 2017; 8:genes8050142. [PMID: 28505071 PMCID: PMC5448016 DOI: 10.3390/genes8050142] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 01/03/2023] Open
Abstract
Overexpression of MYC is a hallmark of many human cancers. The MYC oncogene has long been thought to execute its neoplastic functions by acting as a classic transcription factor, deregulating the expression of a large number of specific target genes. However, MYC’s influence on many of these target genes is rather modest and there is little overlap between MYC regulated genes in different cell types, leaving many mechanistic questions unanswered. Recent advances in the field challenge the dogma further, revealing a role for MYC that extends beyond the traditional concept of a sequence-specific transcription factor. In this article, we review MYC’s function as a regulator of the cancer epigenome and transcriptome. We outline our current understanding of how MYC regulates chromatin structure in both a site-specific and genome-wide fashion, and highlight the implications for therapeutic strategies for cancers with high MYC expression.
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Affiliation(s)
- Candace J Poole
- Augusta University, Department of Biochemistry and Molecular Biology, 1410 Laney-Walker Blvd., Augusta, GA 30912, USA.
| | - Jan van Riggelen
- Augusta University, Department of Biochemistry and Molecular Biology, 1410 Laney-Walker Blvd., Augusta, GA 30912, USA.
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Lupey-Green LN, Moquin SA, Martin KA, McDevitt SM, Hulse M, Caruso LB, Pomerantz RT, Miranda JL, Tempera I. PARP1 restricts Epstein Barr Virus lytic reactivation by binding the BZLF1 promoter. Virology 2017; 507:220-230. [PMID: 28456021 PMCID: PMC5521201 DOI: 10.1016/j.virol.2017.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/14/2017] [Accepted: 04/06/2017] [Indexed: 12/12/2022]
Abstract
The Epstein Barr virus (EBV) genome persists in infected host cells as a chromatinized episome and is subject to chromatin-mediated regulation. Binding of the host insulator protein CTCF to the EBV genome has an established role in maintaining viral latency type, and in other herpesviruses, loss of CTCF binding at specific regions correlates with viral reactivation. Here, we demonstrate that binding of PARP1, an important cofactor of CTCF, at the BZLF1 lytic switch promoter restricts EBV reactivation. Knockdown of PARP1 in the Akata-EBV cell line significantly increases viral copy number and lytic protein expression. Interestingly, CTCF knockdown has no effect on viral reactivation, and CTCF binding across the EBV genome is largely unchanged following reactivation. Moreover, EBV reactivation attenuates PARP activity, and Zta expression alone is sufficient to decrease PARP activity. Here we demonstrate a restrictive function of PARP1 in EBV lytic reactivation.
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Affiliation(s)
- Lena N Lupey-Green
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Stephanie A Moquin
- Gladstone Institute of Virology and Immunology, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Kayla A Martin
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Shane M McDevitt
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Michael Hulse
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Lisa B Caruso
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Richard T Pomerantz
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Jj L Miranda
- Gladstone Institute of Virology and Immunology, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Italo Tempera
- Fels Institute for Cancer Research & Molecular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA.
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30
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Choi H, Lee SK. TAX1BP1 downregulation by EBV-miR-BART15-3p enhances chemosensitivity of gastric cancer cells to 5-FU. Arch Virol 2016; 162:369-377. [PMID: 27757686 DOI: 10.1007/s00705-016-3109-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 10/05/2016] [Indexed: 12/11/2022]
Abstract
MicroRNAs (miRNAs) are a class of noncoding RNA molecules approximately 19 to 25 nucleotides in length that downregulate the expression of target genes at the post-transcriptional level by binding to the 3'-untranslated region (3'-UTR). Epstein-Barr virus (EBV) generates at least 44 miRNAs, but the functions of most of these miRNAs have not yet been identified. Previously, we reported BRUCE as a target of miR-BART15-3p, a miRNA produced by EBV, but our data suggested that there might be other apoptosis-associated target genes of miR-BART15-3p. Thus, in this study, we searched for new target genes of miR-BART15-3p using in silico analyses. We found a possible seed match site in the 3'-UTR of Tax1-binding protein 1 (TAX1BP1). The luciferase activity of a reporter vector including the 3'-UTR of TAX1BP1 was decreased by miR-BART15-3p. MiR-BART15-3p downregulated the expression of TAX1BP1 mRNA and protein in AGS cells, while an inhibitor against miR-BART15-3p upregulated the expression of TAX1BP1 mRNA and protein in AGS-EBV cells. Mir-BART15-3p modulated NF-κB activity in gastric cancer cell lines. Moreover, miR-BART15-3p strongly promoted chemosensitivity to 5-fluorouracil (5-FU). Our results suggest that miR-BART15-3p targets the anti-apoptotic TAX1BP1 gene in cancer cells, causing increased apoptosis and chemosensitivity to 5-FU.
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Affiliation(s)
- Hoyun Choi
- Department of Medical Lifescience, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Republic of Korea
| | - Suk Kyeong Lee
- Department of Medical Lifescience, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Republic of Korea.
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31
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Epigenetic Alterations in Epstein-Barr Virus-Associated Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 879:39-69. [DOI: 10.1007/978-3-319-24738-0_3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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32
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Pentland I, Parish JL. Targeting CTCF to Control Virus Gene Expression: A Common Theme amongst Diverse DNA Viruses. Viruses 2015; 7:3574-85. [PMID: 26154016 PMCID: PMC4517120 DOI: 10.3390/v7072791] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 12/27/2022] Open
Abstract
All viruses target host cell factors for successful life cycle completion. Transcriptional control of DNA viruses by host cell factors is important in the temporal and spatial regulation of virus gene expression. Many of these factors are recruited to enhance virus gene expression and thereby increase virus production, but host cell factors can also restrict virus gene expression and productivity of infection. CCCTC binding factor (CTCF) is a host cell DNA binding protein important for the regulation of genomic chromatin boundaries, transcriptional control and enhancer element usage. CTCF also functions in RNA polymerase II regulation and in doing so can influence co-transcriptional splicing events. Several DNA viruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), Epstein-Barr virus (EBV) and human papillomavirus (HPV) utilize CTCF to control virus gene expression and many studies have highlighted a role for CTCF in the persistence of these diverse oncogenic viruses. CTCF can both enhance and repress virus gene expression and in some cases CTCF increases the complexity of alternatively spliced transcripts. This review article will discuss the function of CTCF in the life cycle of DNA viruses in the context of known host cell CTCF functions.
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Affiliation(s)
- Ieisha Pentland
- School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Joanna L Parish
- School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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33
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CCCTC-binding factor recruitment to the early region of the human papillomavirus 18 genome regulates viral oncogene expression. J Virol 2015; 89:4770-85. [PMID: 25694598 PMCID: PMC4403478 DOI: 10.1128/jvi.00097-15] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 02/12/2015] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Host cell differentiation-dependent regulation of human papillomavirus (HPV) gene expression is required for productive infection. The host cell CCCTC-binding factor (CTCF) functions in genome-wide chromatin organization and gene regulation. We have identified a conserved CTCF binding site in the E2 open reading frame of high-risk HPV types. Using organotypic raft cultures of primary human keratinocytes containing high-risk HPV18 genomes, we show that CTCF recruitment to this conserved site regulates viral gene expression in differentiating epithelia. Mutation of the CTCF binding site increases the expression of the viral oncoproteins E6 and E7 and promotes host cell proliferation. Loss of CTCF binding results in a reduction of a specific alternatively spliced transcript expressed from the early gene region concomitant with an increase in the abundance of unspliced early transcripts. We conclude that high-risk HPV types have evolved to recruit CTCF to the early gene region to control the balance and complexity of splicing events that regulate viral oncoprotein expression. IMPORTANCE The establishment and maintenance of HPV infection in undifferentiated basal cells of the squamous epithelia requires the activation of a subset of viral genes, termed early genes. The differentiation of infected cells initiates the expression of the late viral transcripts, allowing completion of the virus life cycle. This tightly controlled balance of differentiation-dependent viral gene expression allows the virus to stimulate cellular proliferation to support viral genome replication with minimal activation of the host immune response, promoting virus productivity. Alternative splicing of viral mRNAs further increases the complexity of viral gene expression. In this study, we show that the essential host cell protein CTCF, which functions in genome-wide chromatin organization and gene regulation, is recruited to the HPV genome and plays an essential role in the regulation of early viral gene expression and transcript processing. These data highlight a novel virus-host interaction important for HPV pathogenicity.
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Abstract
EBV latent infection is characterized by a highly restricted pattern of viral gene expression. EBV can establish latent infections in multiple different tissue types with remarkable variation and plasticity in viral transcription and replication. During latency, the viral genome persists as a multi-copy episome, a non-integrated-closed circular DNA with nucleosome structure similar to cellular chromosomes. Chromatin assembly and histone modifications contribute to the regulation of viral gene expression, DNA replication, and episome persistence during latency. This review focuses on how EBV latency is regulated by chromatin and its associated processes.
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35
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Schoborg T, Labrador M. Expanding the roles of chromatin insulators in nuclear architecture, chromatin organization and genome function. Cell Mol Life Sci 2014; 71:4089-113. [PMID: 25012699 PMCID: PMC11113341 DOI: 10.1007/s00018-014-1672-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 05/31/2014] [Accepted: 06/23/2014] [Indexed: 01/08/2023]
Abstract
Of the numerous classes of elements involved in modulating eukaryotic chromosome structure and function, chromatin insulators arguably remain the most poorly understood in their contribution to these processes in vivo. Indeed, our view of chromatin insulators has evolved dramatically since their chromatin boundary and enhancer blocking properties were elucidated roughly a quarter of a century ago as a result of recent genome-wide, high-throughput methods better suited to probing the role of these elements in their native genomic contexts. The overall theme that has emerged from these studies is that chromatin insulators function as general facilitators of higher-order chromatin loop structures that exert both physical and functional constraints on the genome. In this review, we summarize the result of recent work that supports this idea as well as a number of other studies linking these elements to a diverse array of nuclear processes, suggesting that chromatin insulators exert master control over genome organization and behavior.
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Affiliation(s)
- Todd Schoborg
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN 37996 USA
- Present Address: Laboratory of Molecular Machines and Tissue Architecture, Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Dr Rm 2122, Bethesda, MD 20892 USA
| | - Mariano Labrador
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN 37996 USA
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36
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Kotova ES, Sorokina IV, Akopov SB, Nikolaev LG, Sverdlov ED. Expression of chicken CTCF gene in COS-1 cells and partial purification of CTCF protein. BIOCHEMISTRY (MOSCOW) 2014; 78:879-83. [PMID: 24228875 DOI: 10.1134/s0006297913080038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The chicken gene for transcription factor CTCF was expressed in COS-1 mammalian cells. The CTCF protein containing polyhistidine tag was partially purified using metallo-affinity and ion-exchange chromatography. The expressed protein localized in the cell nucleus and was shown to be functionally active in the electrophoretic mobility shift assay and specifically interacted with anti-CTCF antibodies.
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Affiliation(s)
- E S Kotova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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37
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Tempera I, Lieberman PM. Epigenetic regulation of EBV persistence and oncogenesis. Semin Cancer Biol 2014; 26:22-9. [PMID: 24468737 DOI: 10.1016/j.semcancer.2014.01.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 12/30/2013] [Accepted: 01/09/2014] [Indexed: 12/29/2022]
Abstract
Epigenetic mechanisms play a fundamental role in generating diverse and heritable patterns of viral and cellular gene expression. Epstein-Barr virus (EBV) can adopt a variety of gene expression programs that are necessary for long-term viral persistence and latency in multiple host-cell types and conditions. The latent viral genomes assemble into chromatin structures with different histone and DNA modifications patterns that control viral gene expression. Variations in nucleosome organization and chromatin conformations can also influence gene expression by coordinating physical interactions between different regulatory elements. The viral-encoded and host-cell factors that control these epigenetic features are beginning to be understood at the genome-wide level. These epigenetic regulators can also influence viral pathogenesis by expanding tissue tropism, evading immune detection, and driving host-cell carcinogenesis. Here, we review some of the recent findings and perspectives on how the EBV epigenome plays a central role in viral latency and viral-associated carcinogenesis.
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Affiliation(s)
- Italo Tempera
- The Fels Institute, Department of Microbiology and Immunology, Temple School of Medicine, Philadelphia, PA 19140, United States.
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38
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Lu F, Tempera I, Lee HT, Dewispelaere K, Lieberman PM. EBNA1 binding and epigenetic regulation of gastrokine tumor suppressor genes in gastric carcinoma cells. Virol J 2014; 11:12. [PMID: 24460791 PMCID: PMC3904692 DOI: 10.1186/1743-422x-11-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 01/17/2014] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Epstein-Barr Virus (EBV) latently infects ~10% of gastric carcinomas (GC). Epstein-Barr Nuclear Antigen 1 (EBNA1) is expressed in EBV-associated GC, and can bind host DNA, where it may impact cellular gene regulation. Here, we show that EBNA1 binds directly to DNA upstream of the divergently transcribed GC-specific tumor suppressor genes gastrokine 1 (GKN1) and gastrokine 2 (GKN2). METHODS We use ChIP-Seq, ChIP-qPCR, and EMSA to demonstrate that EBNA1 binds directly to the GKN1 and GKN2 promoter locus. We generate AGS-EBV, and AGS-EBNA1 cell lines to study the effects of EBNA1 on GKN1 and GKN2 mRNA expression with or without 5' azacytidine treatment. RESULTS We show that gastrokine genes are transcriptionally silenced by DNA methylation. We also show that latent EBV infection further reduces GKN1 and GKN2 expression in AGS gastric carcinoma cells, and that siRNA depletion of EBNA1 partially alleviates this repression. However, ectopic expression of EBNA1 slightly increased GKN1 and GKN2 basal mRNA levels, but reduced their responsiveness to demethylating agent. CONCLUSIONS These findings demonstrate that EBNA1 binds to the divergent promoter of the GKN1 and GKN2 genes in GC cells, and suggest that EBNA1 contributes to the complex transcriptional and epigenetic deregulation of the GKN1 and GKN2 tumor suppressor genes in EBV positive GC.
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Affiliation(s)
| | | | | | | | - Paul M Lieberman
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA.
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Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic gammaherpesvirus which establishes latent infection in endothelial and B cells, as well as in primary effusion lymphoma (PEL). During latency, the viral genome exists as a circular DNA minichromosome (episome) and is packaged into chromatin analogous to human chromosomes. Only a small subset of promoters, those which drive latent RNAs, are active in latent episomes. In general, nucleosome depletion ("open chromatin") is a hallmark of eukaryotic regulatory elements such as promoters and transcriptional enhancers or insulators. We applied formaldehyde-assisted isolation of regulatory elements (FAIRE) followed by next-generation sequencing to identify regulatory elements in the KSHV genome and integrated these data with previously identified locations of histone modifications, RNA polymerase II occupancy, and CTCF binding sites. We found that (i) regions of open chromatin were not restricted to the transcriptionally defined latent loci; (ii) open chromatin was adjacent to regions harboring activating histone modifications, even at transcriptionally inactive loci; and (iii) CTCF binding sites fell within regions of open chromatin with few exceptions, including the constitutive LANA promoter and the vIL6 promoter. FAIRE-identified nucleosome depletion was similar among B and endothelial cell lineages, suggesting a common viral genome architecture in all forms of latency.
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Cha S, Seo T. Viral genome maintenance and latent replication of human gammaherpesviruses. Future Virol 2013. [DOI: 10.2217/fvl.13.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
During gammaherpesvirus latency, only a few genes are expressed and required for maintenance of viral latency over a long period. While the expressed latent viral proteins play functional roles in viral latent DNA replication, they do not have replication-associated enzymatic activity such as polymerase or helicase activity. Viral genomes are detected in a similar copy number per infected cell, suggesting that the viral genome is replicated and segregated using host replication machinery. Kaposi’s sarcoma-associated herpesvirus and EBV have trans-acting elements required for viral genome maintenance during latency; LANA1 and EBNA1, respectively. The proteins recruit host replication-associated proteins at their latent origins, leading to initiation of viral replication and segregation with host chromosomes once per cell cycle. In addition, viral latent origins (cis-elements) provide trans-element-binding sites as well as a sufficient space for recruitment of cellular factors. In this review, we describe the molecular mechanisms required for replication of the viral genome during latency, including interactions with cellular factors and the interplay between viral trans- and cis-elements.
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Affiliation(s)
- Seho Cha
- Department of Life Science, Dongguk University-Seoul, 26, 3 Pil-dong, Jung-gu, Seoul, 100-715, Republic of Korea
| | - Taegun Seo
- Department of Life Science, Dongguk University-Seoul, 26, 3 Pil-dong, Jung-gu, Seoul, 100-715, Republic of Korea.
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Deng Z, Wang Z, Stong N, Plasschaert R, Moczan A, Chen HS, Hu S, Wikramasinghe P, Davuluri RV, Bartolomei MS, Riethman H, Lieberman PM. A role for CTCF and cohesin in subtelomere chromatin organization, TERRA transcription, and telomere end protection. EMBO J 2012; 31:4165-78. [PMID: 23010778 PMCID: PMC3492729 DOI: 10.1038/emboj.2012.266] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 08/29/2012] [Indexed: 01/04/2023] Open
Abstract
The contribution of human subtelomeric DNA and chromatin organization to telomere integrity and chromosome end protection is not yet understood in molecular detail. Here, we show by ChIP-Seq that most human subtelomeres contain a CTCF- and cohesin-binding site within ∼1-2 kb of the TTAGGG repeat tract and adjacent to a CpG-islands implicated in TERRA transcription control. ChIP-Seq also revealed that RNA polymerase II (RNAPII) was enriched at sites adjacent to the CTCF sites and extending towards the telomere repeat tracts. Mutation of CTCF-binding sites in plasmid-borne promoters reduced transcriptional activity in an orientation-dependent manner. Depletion of CTCF by shRNA led to a decrease in TERRA transcription, and a loss of cohesin and RNAPII binding to the subtelomeres. Depletion of either CTCF or cohesin subunit Rad21 caused telomere-induced DNA damage foci (TIF) formation, and destabilized TRF1 and TRF2 binding to the TTAGGG proximal subtelomere DNA. These findings indicate that CTCF and cohesin are integral components of most human subtelomeres, and important for the regulation of TERRA transcription and telomere end protection.
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Affiliation(s)
- Zhong Deng
- The Wistar Institute, Philadelphia, PA, USA
| | - Zhuo Wang
- The Wistar Institute, Philadelphia, PA, USA
| | - Nick Stong
- The Wistar Institute, Philadelphia, PA, USA
| | - Robert Plasschaert
- Cell and Developmental Biology Department, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | - Sufeng Hu
- The Wistar Institute, Philadelphia, PA, USA
| | | | | | - Marisa S Bartolomei
- Cell and Developmental Biology Department, University of Pennsylvania, Philadelphia, PA, USA
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Boreström C, Forsman A, Rüetschi U, Rymo L. E2F1, ARID3A/Bright and Oct-2 factors bind to the Epstein-Barr virus C promoter, EBNA1 and oriP, participating in long-distance promoter-enhancer interactions. J Gen Virol 2012; 93:1065-1075. [PMID: 22302879 DOI: 10.1099/vir.0.038752-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The Epstein-Barr virus (EBV) C promoter (Cp) regulates several genes required for B-cell proliferation in latent EBV infection. The family of repeats (FR) region of the latent origin of plasmid replication (oriP) functions as an Epstein-Barr nuclear antigen 1 (EBNA1)-dependent distant enhancer of Cp activity, and the enhancer-promoter interaction is mediated by a higher-order multi-protein complex containing several copies of EBNA1. Using DNA-affinity purification with a 170 bp region of the Cp in combination with mass spectrometry, we identified the cell cycle-regulatory protein E2F1, the E2F-binding protein ARID3A, and the B-cell-specific transcription factor Oct-2 as components of this multi-protein complex. Binding of the three factors to the FR region of oriP was determined by DNA-affinity and immunoblot analysis. Co-immunoprecipitation and proximity ligation analysis revealed that the three factors, E2F1, ARID3A and Oct-2, interact with each other as well as with EBNA1 in the nuclei of EBV-positive cells. Using the chromatin immunoprecipitation assay, we showed that E2F1 and Oct-2 interacted with the FR part of oriP and the Cp, but the ARID3A interaction was, however, only detected at the Cp. Our findings support the hypothesis that EBNA1 initiates transcription at the Cp via interactions between multiple EBNA1 homodimers and cellular transcription factors in a large molecular machinery that forms a dynamic interaction between Cp and FR.
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Affiliation(s)
- Cecilia Boreström
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, University of Gothenburg, SE-41345 Gothenburg, Sweden
| | - Alma Forsman
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, University of Gothenburg, SE-41345 Gothenburg, Sweden
| | - Ulla Rüetschi
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, University of Gothenburg, SE-41345 Gothenburg, Sweden
| | - Lars Rymo
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, University of Gothenburg, SE-41345 Gothenburg, Sweden
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Yang J, Corces VG. Insulators, long-range interactions, and genome function. Curr Opin Genet Dev 2012; 22:86-92. [PMID: 22265227 DOI: 10.1016/j.gde.2011.12.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/18/2011] [Accepted: 12/23/2011] [Indexed: 01/11/2023]
Abstract
Insulators are DNA-protein complexes that can mediate interactions in cis or trans between different regions of the genome. Although originally defined on the basis of their ability to block enhancer-promoter communication or to serve as barriers against the spreading of heterochromatin in reporter systems, recent information suggests that their function is more nuanced and depends on the nature of the sequences brought together by contacts between specific insulator sites. Here we provide an overview of new evidence that has uncovered a wide range of functions for these sequences in addition to their two classical roles.
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Affiliation(s)
- Jingping Yang
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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Hughes DJ, Marendy EM, Dickerson CA, Yetming KD, Sample CE, Sample JT. Contributions of CTCF and DNA methyltransferases DNMT1 and DNMT3B to Epstein-Barr virus restricted latency. J Virol 2012; 86:1034-45. [PMID: 22072770 PMCID: PMC3255836 DOI: 10.1128/jvi.05923-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/27/2011] [Indexed: 12/29/2022] Open
Abstract
Establishment of persistent Epstein-Barr virus (EBV) infection requires transition from a program of full viral latency gene expression (latency III) to one that is highly restricted (latency I and 0) within memory B lymphocytes. It is well established that DNA methylation plays a critical role in EBV gene silencing, and recently the chromatin boundary protein CTCF has been implicated as a pivotal regulator of latency via its binding to several loci within the EBV genome. One notable site is upstream of the common EBNA gene promoter Cp, at which CTCF may act as an enhancer-blocking factor to initiate and maintain silencing of EBNA gene transcription. It was previously suggested that increased expression of CTCF may underlie its potential to promote restricted latency, and here we also noted elevated levels of DNA methyltransferase 1 (DNMT1) and DNMT3B associated with latency I. Within B-cell lines that maintain latency I, however, stable knockdown of CTCF, DNMT1, or DNMT3B or of DNMT1 and DNMT3B in combination did not result in activation of latency III protein expression or EBNA gene transcription, nor did knockdown of DNMTs significantly alter CpG methylation within Cp. Thus, differential expression of CTCF and DNMT1 and -3B is not critical for maintenance of restricted latency. Finally, mutant EBV lacking the Cp CTCF binding site exhibited sustained Cp activity relative to wild-type EBV in a recently developed B-cell superinfection model but ultimately was able to transition to latency I, suggesting that CTCF contributes to but is not necessarily essential for the establishment of restricted latency.
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Affiliation(s)
- David J Hughes
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, and Penn State Hershey Cancer Institute, Hershey, Pennsylvania, USA
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45
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Wang FW, Wu XR, Liu WJ, Liang YJ, Huang YF, Liao YJ, Shao CK, Zong YS, Mai SJ, Xie D. The nucleotide polymorphisms within the Epstein-Barr virus C and Q promoters from nasopharyngeal carcinoma affect transcriptional activity in vitro. Eur Arch Otorhinolaryngol 2011; 269:931-8. [PMID: 22146864 DOI: 10.1007/s00405-011-1862-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 11/22/2011] [Indexed: 01/13/2023]
Abstract
Epstein-Barr virus (EBV) is a ubiquitous human gamma herpesvirus that is associated with Burkitt's lymphoma (BL), gastric carcinoma, nasopharyngeal carcinoma (NPC), and NK/T-cell lymphoma. Two viral promoters, Cp and Qp, are important for EBV latent infection. The latency Cp, which is used in primary infection, drives expression of the full spectrum of EBV nuclear antigens. Qp is active in EBV-associated tumors and drives the latency I/II expression pattern. In this study, we determined nucleotides polymorphisms in the Cp and Qp promoter regions in peripheral blood mononuclear cells (PBMCs) from Cantonese healthy carriers and in biopsies of NPC, nasal NK/T lymphoma, BL, and gastric carcinoma. The sequence changes of -12G>T and +69 C>T in Cp and -197 G>A and +1 G>C in Qp were frequently identified in NPC. Transient transfection studies using luciferase gene reporters revealed a significant reduction (57.11%) in gene expression from the Cp +69T variant and increased expression (43.5%) from the Qp +1C variant compared to the prototype, suggesting that these sequence variations affect promoter activity. Our results indicate that the nucleotides polymorphisms in Cp and Qp occur frequently in NPC and might contribute to the oncogenesis of EBV.
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Affiliation(s)
- Feng-Wei Wang
- The State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, No. 651, Dongfeng Road East, Guangzhou, 510060, China
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The insulator protein CTCF binding sites in the orf73/LANA promoter region of herpesvirus saimiri are involved in conferring episomal stability in latently infected human T cells. J Virol 2011; 86:1862-73. [PMID: 22130528 DOI: 10.1128/jvi.06295-11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Herpesviruses establish latency in suitable cells of the host organism after a primary lytic infection. Subgroup C strains of herpesvirus saimiri (HVS), a primate gamma-2 herpesvirus, are able to transform human and other primate T lymphocytes to stable growth in vitro. The viral genomes persist as nonintegrated, circular, and histone-associated episomes in the nuclei of those latently infected T cells. Epigenetic modifications of episomes are essential to restrict the transcription during latency to selected viral genes, such as the viral oncogenes stpC/tip and the orf73/LANA. In this study, we describe a genome-wide chromatin immunoprecipitation-on-chip (ChIP-on-chip) analysis to profile the occupancy of CTCF on the latent HVS genome. We then focused on two distinct, conserved CTCF binding sites (CBS) within the orf73/LANA promoter region. Analysis of recombinant viruses harboring deletions or mutations within the CBS indicated that the lytic replication of such viruses is not substantially influenced by CTCF. However, T cells latently infected with CBS mutants were impaired in their proliferation abilities and showed a significantly reduced episomal maintenance. We detected a reduced transcription of the orf73/LANA gene in the T cells, corresponding to the reduced viral genomes; this might contribute to the loss of HVS episomes, as LANA is central in the maintenance of viral episomes in the dividing T cell populations. These data demonstrate that the episomal stability of HVS genomes in latently infected human T cells is dependent on CTCF.
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47
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Szpara ML, Tafuri YR, Parsons L, Shamim SR, Verstrepen KJ, Legendre M, Enquist LW. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses. PLoS Pathog 2011; 7:e1002282. [PMID: 22022263 PMCID: PMC3192842 DOI: 10.1371/journal.ppat.1002282] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 08/10/2011] [Indexed: 12/17/2022] Open
Abstract
Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1) and 2, and varicella zoster virus (VZV). These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV), causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs), a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit limited sequence heterogeneity, which likely seeds future strain evolution. Alphaherpesviruses such as herpes simplex virus (HSV) are ubiquitous in the human population. HSV causes oral and genital lesions, and has co-morbidities in acquisition and spread of human immunodeficiency virus (HIV). The lack of a vaccine for HSV hinders medical progress for both of these infections. A related veterinary alphaherpesvirus, pseudorabies virus (PRV), has long served as a model for HSV vaccine development, because of their similar pathogenesis, neuronal spread, and infectious cycle. We present here the first full genome characterization of a live PRV vaccine strain, Bartha, and reveal a spectrum of unique mutations that are absent from two divergent wild-type PRV strains. These mutations can now be examined individually for their contribution to vaccine strain attenuation and for potential use in HSV vaccine development. These inter-strain comparisons also revealed an abundance of short repetitive elements in the PRV genome, a pattern which is repeated in other herpesvirus genomes and even the unrelated Mimivirus. We provide the first global characterization of repeats in viruses, comparing both their presence and their variation among different viral strains and species. Repetitive elements such as these have been shown to serve as hotspots of variation between individuals or strains of other organisms, generating adaptations or even disease states through changes in length of DNA-binding sites, protein folding motifs, and other structural elements. These data suggest for the first time that similar mechanisms could be widely distributed in viral biology as well.
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Affiliation(s)
- Moriah L. Szpara
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Yolanda R. Tafuri
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Lance Parsons
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - S. Rafi Shamim
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Kevin J. Verstrepen
- VIB lab for Systems Biology and CMPG Lab for Genetics and Genomics, KULeuven, Gaston Geenslaan 1, Leuven, Belgium
| | - Matthieu Legendre
- Structural & Genomic Information Laboratory (CNRS, UPR2589), Mediterranean Institute of Microbiology, Aix-Marseille Université, Marseille, France
| | - L. W. Enquist
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
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trans-Repression of protein expression dependent on the Epstein-Barr virus promoter Wp during latency. J Virol 2011; 85:11435-47. [PMID: 21865378 DOI: 10.1128/jvi.05158-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
An ordered silencing of Epstein-Barr virus (EBV) latency gene transcription is critical for establishment of persistent infection within B lymphocytes, yet the mechanisms responsible and the role that the virus itself may play are unclear. Here we describe two B-cell superinfection models with which to address these problems. In the first, Burkitt lymphoma (BL) cells that maintain latency I, when superinfected, initially supported transcription from the common EBNA promoters Wp and Cp (latency III) but ultimately transitioned to latency I (Cp/Wp silent), an essential requirement for establishment of EBV latency in vivo. We used this model to test whether the early lytic-cycle gene BHLF1, implicated in silencing of the Cp/Wp locus, is required to establish latency I. Upon superinfection with EBV deleted for the BHLF1 locus, however, we have demonstrated that BHLF1 is not essential for this aspect of EBV latency. In the second model, BL cells that maintain Wp-restricted latency, a variant program in which Cp is silent but Wp remains active, sustained the latency III program of transcription from the superinfecting-virus genomes, failing to transition to latency I. Importantly, there was substantial reduction in Wp-mediated protein expression from endogenous EBV genomes, in the absence of Cp reactivation, that could occur independent of a parallel decrease in mRNA. Thus, our data provide evidence of a novel, potentially posttranscriptional mechanism for trans-repression of Wp-dependent gene expression. We suggest that this may ensure against overexpression of the EBV nuclear antigens (EBNAs) prior to the transcriptional repression of Wp in cis that occurs upon activation of Cp.
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Nevels M, Nitzsche A, Paulus C. How to control an infectious bead string: nucleosome-based regulation and targeting of herpesvirus chromatin. Rev Med Virol 2011; 21:154-80. [PMID: 21538665 DOI: 10.1002/rmv.690] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Herpesvirus infections of humans can cause a broad variety of symptoms ranging from mild afflictions to life-threatening disease. During infection, the large double-stranded DNA genomes of all herpesviruses are transcribed, replicated and encapsidated in the host cell nucleus, where DNA is typically structured and manoeuvred through nucleosomes. Nucleosomes individually assemble DNA around core histone octamers to form 'beads-on-a-string' chromatin fibres. Herpesviruses have responded to the advantages and challenges of chromatin formation in biologically unique ways. Although herpesvirus DNA is devoid of histones within nucleocapsids, nuclear viral genomes most likely form irregularly arranged or unstable nucleosomes during productive infection, and regular nucleosomal arrays resembling host cell chromatin in latently infected cells. Besides variations in nucleosome density, herpesvirus chromatin 'bead strings' undergo dynamic changes in histone composition and modification during the different stages of productive replication, latent infection and reactivation from latency, raising the likely possibility that epigenetic processes may dictate, at least in part, the outcome of infection and ensuing pathogenesis. Here, we summarise and discuss several new and important aspects regarding the nucleosome-based mechanisms that regulate herpesvirus chromatin structure and function in infected cells. Special emphasis is given to processes of histone deposition, histone variant exchange and covalent histone modification in relation to the transcription from the viral genome during productive and latent infections by human cytomegalovirus and herpes simplex virus type 1. We also present an overview on emerging histone-directed antiviral strategies that may be developed into 'epigenetic therapies' to improve current prevention and treatment options targeting herpesvirus infection and disease.
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Affiliation(s)
- Michael Nevels
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Germany.
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50
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Tempera I, Klichinsky M, Lieberman PM. EBV latency types adopt alternative chromatin conformations. PLoS Pathog 2011; 7:e1002180. [PMID: 21829357 PMCID: PMC3145795 DOI: 10.1371/journal.ppat.1002180] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 06/09/2011] [Indexed: 12/18/2022] Open
Abstract
Epstein-Barr Virus (EBV) can establish latent infections with distinct gene expression patterns referred to as latency types. These different latency types are epigenetically stable and correspond to different promoter utilization. Here we explore the three-dimensional conformations of the EBV genome in different latency types. We employed Chromosome Conformation Capture (3C) assay to investigate chromatin loop formation between the OriP enhancer and the promoters that determine type I (Qp) or type III (Cp) gene expression. We show that OriP is in close physical proximity to Qp in type I latency, and to Cp in type III latency. The cellular chromatin insulator and boundary factor CTCF was implicated in EBV chromatin loop formation. Combining 3C and ChIP assays we found that CTCF is physically associated with OriP-Qp loop formation in type I and OriP-Cp loop formation in type III latency. Mutations in the CTCF binding site located at Qp disrupt loop formation between Qp and OriP, and lead to the activation of Cp transcription. Mutation of the CTCF binding site at Cp, as well as siRNA depletion of CTCF eliminates both OriP-associated loops, indicating that CTCF plays an integral role in loop formation. These data indicate that epigenetically stable EBV latency types adopt distinct chromatin architectures that depend on CTCF and mediate alternative promoter targeting by the OriP enhancer. Epstein-Barr Virus (EBV) latent infection is associated with several human malignancies. The viral genes expressed during latent infection can vary depending on host cell or tumor type. The different gene expression programs, referred to as latency types, are determined by alternative viral promoter usage. In this work, we investigate how differential DNA loop formation regulates viral promoter selection in different latency types. We use chromatin conformation capture methods to demonstrate that the transcriptional enhancer at OriP forms a stable loop with one of two different promoters, depending on the latency type. In type I latency, OriP forms a loop with the active Q promoter (Qp). In type III latency, OriP forms a loop with the active C promoter (Cp). Loop formation was mediated, in part, by CTCF binding sites located within the loops. Mutation in the CTCF binding site located at Qp caused a loss of OriP-Qp loop formation, a loss of Qp transcription, and a reactivation of Cp transcription from an alternative loop formed with OriP-Cp. These findings indicate that OriP loop formation is an integral component of promoter selection, and that chromatin conformation may determine EBV latency type.
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Affiliation(s)
- Italo Tempera
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Michael Klichinsky
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Paul M. Lieberman
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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