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Roy Chowdhury N, Gurevich V, Shamay M. KSHV genome harbors both constitutive and lytically induced enhancers. J Virol 2024; 98:e0017924. [PMID: 38695538 PMCID: PMC11237633 DOI: 10.1128/jvi.00179-24] [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: 01/30/2024] [Accepted: 04/03/2024] [Indexed: 06/14/2024] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the gamma-herpesvirus family and is a well-known human oncogenic virus. In infected cells, the viral genome of 165 kbp is circular DNA wrapped in chromatin. The tight control of gene expression is critical for latency, the transition into the lytic phase, and the development of viral-associated malignancies. Distal cis-regulatory elements, such as enhancers and silencers, can regulate gene expression in a position- and orientation-independent manner. Open chromatin is another characteristic feature of enhancers. To systematically search for enhancers, we cloned all the open chromatin regions in the KSHV genome downstream of the luciferase gene and tested their enhancer activity in infected and uninfected cells. A silencer was detected upstream of the latency-associated nuclear antigen promoter. Two constitutive enhancers were identified in the K12p-OriLyt-R and ORF29 Intron regions, where ORF29 Intron is a tissue-specific enhancer. The following promoters: OriLyt-L, PANp, ALTp, and the terminal repeats (TRs) acted as lytically induced enhancers. The expression of the replication and transcription activator (RTA), the master regulator of the lytic cycle, was sufficient to induce the activity of lytic enhancers in uninfected cells. We propose that the TRs that span about 24 kbp region serve as a "viral super-enhancer" that integrates the repressive effect of the latency-associated nuclear antigen (LANA) with the activating effect of RTA. Utilizing CRISPR activation and interference techniques, we determined the connections between these enhancers and their regulated genes. The silencer and enhancers described here provide an additional layer to the complex gene regulation of herpesviruses.IMPORTANCEIn this study, we performed a systematic functional assay to identify cis-regulatory elements within the genome of the oncogenic herpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV). Similar to other herpesviruses, KSHV presents both latent and lytic phases. Therefore, our assays were performed in uninfected cells, during latent infection, and under lytic conditions. We identified two constitutive enhancers, one of which seems to be a tissue-specific enhancer. In addition, four lytically induced enhancers, which are all responsive to the replication and transcription activator (RTA), were identified. Furthermore, a silencer was identified between the major latency promoter and the lytic gene locus. Utilizing CRISPR activation and interference techniques, we determined the connections between these enhancers and their regulated genes. The terminal repeats, spanning a region of about 24 kbp, seem like a "viral super-enhancer" that integrates the repressive effect of the latency-associated nuclear antigen (LANA) with the activating effect of RTA to regulate latency to lytic transition.
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Affiliation(s)
- Nilabja Roy Chowdhury
- Daniella Lee Casper Laboratory in Viral Oncology, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Vyacheslav Gurevich
- Daniella Lee Casper Laboratory in Viral Oncology, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Meir Shamay
- Daniella Lee Casper Laboratory in Viral Oncology, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
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2
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Ji Y, Chen W, Wang X. Bromodomain and Extraterminal Domain Protein 2 in Multiple Human Diseases. J Pharmacol Exp Ther 2024; 389:277-288. [PMID: 38565308 DOI: 10.1124/jpet.123.002036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/04/2024] Open
Abstract
Bromodomain and extraterminal domain protein 2 (BRD2), a member of the bromodomain and extraterminal domain (BET) protein family, is a crucial epigenetic regulator with significant function in various diseases and cellular processes. The central function of BRD2 is modulating gene transcription by binding to acetylated lysine residues on histones and transcription factors. This review highlights key findings on BRD2 in recent years, emphasizing its roles in maintaining genomic stability, influencing chromatin spatial organization, and participating in transcriptional regulation. BRD2's diverse functions are underscored by its involvement in diseases such as malignant tumors, neurologic disorders, inflammatory conditions, metabolic diseases, and virus infection. Notably, the potential role of BRD2 as a diagnostic marker and therapeutic target is discussed in the context of various diseases. Although pan inhibitors targeting the BET family have shown promise in preclinical studies, a critical need exists for the development of highly selective BRD2 inhibitors. In conclusion, this review offers insights into the multifaceted nature of BRD2 and calls for continued research to unravel its intricate mechanisms and harness its therapeutic potential. SIGNIFICANCE STATEMENT: BRD2 is involved in the occurrence and development of diseases through maintaining genomic stability, influencing chromatin spatial organization, and participating in transcriptional regulation. Targeting BRD2 through protein degradation-targeting complexes technology is emerging as a promising therapeutic approach for malignant cancer and inflammatory diseases.
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Affiliation(s)
- Yikang Ji
- Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology
| | - Wantao Chen
- Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology
| | - Xu Wang
- Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology
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3
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Ye X, Guerin LN, Chen Z, Rajendren S, Dunker W, Zhao Y, Zhang R, Hodges E, Karijolich J. Enhancer-promoter activation by the Kaposi sarcoma-associated herpesvirus episome maintenance protein LANA. Cell Rep 2024; 43:113888. [PMID: 38416644 PMCID: PMC11005752 DOI: 10.1016/j.celrep.2024.113888] [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: 05/02/2023] [Revised: 12/29/2023] [Accepted: 02/14/2024] [Indexed: 03/01/2024] Open
Abstract
Higher-order genome structure influences the transcriptional regulation of cellular genes through the juxtaposition of regulatory elements, such as enhancers, close to promoters of target genes. While enhancer activation has emerged as an important facet of Kaposi sarcoma-associated herpesvirus (KSHV) biology, the mechanisms controlling enhancer-target gene expression remain obscure. Here, we discover that the KSHV genome tethering protein latency-associated nuclear antigen (LANA) potentiates enhancer-target gene expression in primary effusion lymphoma (PEL), a highly aggressive B cell lymphoma causally associated with KSHV. Genome-wide analyses demonstrate increased levels of enhancer RNA transcription as well as activating chromatin marks at LANA-bound enhancers. 3D genome conformation analyses identified genes critical for latency and tumorigenesis as targets of LANA-occupied enhancers, and LANA depletion results in their downregulation. These findings reveal a mechanism in enhancer-gene coordination and describe a role through which the main KSHV tethering protein regulates essential gene expression in PEL.
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Affiliation(s)
- Xiang Ye
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Lindsey N Guerin
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ziche Chen
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Suba Rajendren
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - William Dunker
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Yang Zhao
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ruilin Zhang
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Emily Hodges
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt-Ingram Cancer Center, Nashville, TN 37232, USA; Vanderbilt Genetics Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - John Karijolich
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt-Ingram Cancer Center, Nashville, TN 37232, USA; Vanderbilt Institute for Infection, Immunology, and Inflammation, Nashville, TN 37232, USA; Vanderbilt Center for Immunobiology, Nashville, TN 37232, USA.
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4
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Li S, Wang M, Van Sciver N, Szymula A, Tumuluri VS, George A, Ramachandran A, Raina K, Costa CN, Zhao B, Kazemian M, Simas JP, Kaye KM. Kaposi's sarcoma herpesvirus latency-associated nuclear antigen broadly regulates viral gene expression and is essential for lytic infection. PLoS Pathog 2024; 20:e1011907. [PMID: 38232124 PMCID: PMC10793894 DOI: 10.1371/journal.ppat.1011907] [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: 08/08/2023] [Accepted: 12/18/2023] [Indexed: 01/19/2024] Open
Abstract
Kaposi's sarcoma herpesvirus (KSHV) is a leading cause of malignancy in AIDS and current therapies are limited. Like all herpesviruses, KSHV infection can be latent or lytic. KSHV latency-associated nuclear antigen (LANA) is essential for viral genome persistence during latent infection. LANA also maintains latency by antagonizing expression and function of the KSHV lytic switch protein, RTA. Here, we find LANA null KSHV is not capable of lytic replication, indicating a requirement for LANA. While LANA promoted both lytic and latent gene expression in cells partially permissive for lytic infection, it repressed expression in non-permissive cells. Importantly, forced RTA expression in non-permissive cells led to induction of lytic infection and LANA switched to promote, rather than repress, most lytic viral gene expression. When basal viral gene expression levels were high, LANA promoted expression, but repressed expression at low basal levels unless RTA expression was forcibly induced. LANA's effects were broad, but virus gene specific, extending to an engineered, recombinant viral GFP under control of host EF1α promoter, but not to host EF1α. Together, these results demonstrate that, in addition to its essential role in genome maintenance, LANA broadly regulates viral gene expression, and is required for high levels of lytic gene expression during lytic infection. Strategies that target LANA are expected to abolish KSHV infection.
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Affiliation(s)
- Shijun Li
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mengbo Wang
- Department of Computer Science, Purdue University, West Lafayette, Indiana
| | - Nicholas Van Sciver
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Agnieszka Szymula
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Vinayak Sadasivam Tumuluri
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Athira George
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Akshaya Ramachandran
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Komal Raina
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Catarina N. Costa
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, Lisboa, Portugal
- Universidade Católica Portuguesa, Católica Medical School, Católica Biomedical Research, Palma de Cima, Portugal
| | - Bo Zhao
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Majid Kazemian
- Department of Computer Science, Purdue University, West Lafayette, Indiana
- Department of Biochemistry, Purdue University, West Lafayette, Indiana
| | - J. Pedro Simas
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, Lisboa, Portugal
- Universidade Católica Portuguesa, Católica Medical School, Católica Biomedical Research, Palma de Cima, Portugal
| | - Kenneth M. Kaye
- Departments of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute of Harvard University and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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5
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Berwanger A, Stein SC, Kany AM, Gartner M, Loretz B, Lehr CM, Hirsch AKH, Schulz TF, Empting M. Disrupting Kaposi's Sarcoma-Associated Herpesvirus (KSHV) Latent Replication with a Small Molecule Inhibitor. J Med Chem 2023; 66:10782-10790. [PMID: 37506283 PMCID: PMC10424179 DOI: 10.1021/acs.jmedchem.3c00990] [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: 06/04/2023] [Indexed: 07/30/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) can establish latent lifelong infections in infected individuals. During viral latency, the latency-associated nuclear antigen (LANA) mediates the replication of the latent viral genome in dividing cells and tethers them to mitotic chromosomes, thus ensuring their partitioning into daughter cells during mitosis. This study aims to inhibit Kaposi's sarcoma-associated herpesvirus (KSHV) latent replication by targeting the LANA-DNA interaction using small molecular entities. Drawing from first-generation inhibitors and using growth vectors identified through STD-NMR, we expanded these compounds using Suzuki-Miyaura cross-coupling. This led to a deeper understanding of SAR achieved by microscale thermophoresis (MST) measurements and cell-free tests via electrophoretic mobility shift assays (EMSA). Our most potent compounds successfully inhibit LANA-mediated replication in cell-based assays and demonstrate favorable in vitro ADMET-profiles, including suitable metabolic stability, Caco-2 permeability, and cytotoxicity. These compounds could serve as qualified leads for the future refinement of small molecule inhibitors of KSHV latent replication.
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Affiliation(s)
- Aylin Berwanger
- Helmholtz-Institute
for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
- Department
of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
- German
Centre for Infection Research (DZIF), Partner
Site Hannover-Braunschweig, 66123 Saarbrücken, Germany
| | - Saskia C. Stein
- German
Centre for Infection Research (DZIF), Partner
Site Hannover-Braunschweig, 66123 Saarbrücken, Germany
- Institute
of Virology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence RESIST (EXC 2155), Hannover
Medical School, Carl-Neuberg-Str.
1, 30625 Hannover, Germany
| | - Andreas M. Kany
- Helmholtz-Institute
for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
| | - Melissa Gartner
- Department
of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
| | - Brigitta Loretz
- Helmholtz-Institute
for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
| | - Claus-Michael Lehr
- Helmholtz-Institute
for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
- Department
of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
| | - Anna K. H. Hirsch
- Helmholtz-Institute
for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
- Department
of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
- Cluster
of Excellence RESIST (EXC 2155), Hannover
Medical School, Carl-Neuberg-Str.
1, 30625 Hannover, Germany
| | - Thomas F. Schulz
- German
Centre for Infection Research (DZIF), Partner
Site Hannover-Braunschweig, 66123 Saarbrücken, Germany
- Institute
of Virology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence RESIST (EXC 2155), Hannover
Medical School, Carl-Neuberg-Str.
1, 30625 Hannover, Germany
| | - Martin Empting
- Helmholtz-Institute
for Pharmaceutical Research Saarland (HIPS), Campus E8.1, 66123 Saarbrücken, Germany
- Department
of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
- German
Centre for Infection Research (DZIF), Partner
Site Hannover-Braunschweig, 66123 Saarbrücken, Germany
- Cluster
of Excellence RESIST (EXC 2155), Hannover
Medical School, Carl-Neuberg-Str.
1, 30625 Hannover, Germany
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6
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Tan M, Li S, Juillard F, Chitas R, Custódio TF, Xue H, Szymula A, Sun Q, Liu B, Álvarez ÁL, Chen S, Huang J, Simas JP, McVey CE, Kaye KM. MLL1 is regulated by KSHV LANA and is important for virus latency. Nucleic Acids Res 2021; 49:12895-12911. [PMID: 34850113 PMCID: PMC8682764 DOI: 10.1093/nar/gkab1094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/29/2021] [Accepted: 10/20/2021] [Indexed: 01/19/2023] Open
Abstract
Mixed lineage leukemia 1 (MLL1) is a histone methyltransferase. Kaposi's sarcoma-associated herpesvirus (KSHV) is a leading cause of malignancy in AIDS. KSHV latently infects tumor cells and its genome is decorated with epigenetic marks. Here, we show that KSHV latency-associated nuclear antigen (LANA) recruits MLL1 to viral DNA where it establishes H3K4me3 modifications at the extensive KSHV terminal repeat elements during primary infection. LANA interacts with MLL1 complex members, including WDR5, integrates into the MLL1 complex, and regulates MLL1 activity. We describe the 1.5-Å crystal structure of N-terminal LANA peptide complexed with MLL1 complex member WDR5, which reveals a potential regulatory mechanism. Disruption of MLL1 expression rendered KSHV latency establishment highly deficient. This deficiency was rescued by MLL1 but not by catalytically inactive MLL1. Therefore, MLL1 is LANA regulable and exerts a central role in virus infection. These results suggest broad potential for MLL1 regulation, including by non-host factors.
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Affiliation(s)
- Min Tan
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Shijun Li
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Franceline Juillard
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Rute Chitas
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2780-157, Portugal
| | - Tânia F Custódio
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2780-157, Portugal
| | - Han Xue
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 200031 Shanghai, China
| | - Agnieszka Szymula
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Qiming Sun
- Departments of Biochemistry and Cardiology, Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Bing Liu
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Ángel L Álvarez
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - She Chen
- Proteomics Center, National Institute of Biological Sciences, Beijing 102206, China
| | - Jing Huang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine 200125 Shanghai, China
| | - J Pedro Simas
- Instituto de Medicina Molecular, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal.,Católica Biomedical Research, Católica Medical School, Universidade Católica Portuguesa, Palma de Cima, 1649-023 Lisboa, Portugal
| | - Colin E McVey
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2780-157, Portugal
| | - Kenneth M Kaye
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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7
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Lara-Ureña N, García-Domínguez M. Relevance of BET Family Proteins in SARS-CoV-2 Infection. Biomolecules 2021; 11:1126. [PMID: 34439792 PMCID: PMC8391731 DOI: 10.3390/biom11081126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 12/14/2022] Open
Abstract
The recent pandemic we are experiencing caused by the coronavirus disease 2019 (COVID-19) has put the world's population on the rack, with more than 191 million cases and more than 4.1 million deaths confirmed to date. This disease is caused by a new type of coronavirus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A massive proteomic analysis has revealed that one of the structural proteins of the virus, the E protein, interacts with BRD2 and BRD4 proteins of the Bromodomain and Extra Terminal domain (BET) family of proteins. BETs are essential to cell cycle progression, inflammation and immune response and have also been strongly associated with infection by different types of viruses. The fundamental role BET proteins play in transcription makes them appropriate targets for the propagation strategies of some viruses. Recognition of histone acetylation by BET bromodomains is essential for transcription control. The development of drugs mimicking acetyl groups, and thereby able to displace BET proteins from chromatin, has boosted interest on BETs as attractive targets for therapeutic intervention. The success of these drugs against a variety of diseases in cellular and animal models has been recently enlarged with promising results from SARS-CoV-2 infection studies.
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Affiliation(s)
| | - Mario García-Domínguez
- Andalusian Centre for Molecular Biology and Regenerative Medicine (CABIMER), CSIC-Universidad de Sevilla-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain;
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8
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Hashmi HF, Waseem M, Ali SS, Hussain Z, Chen K. Structural and Biophysical Investigation of the Key Hotspots on the Surface of Epstein-Barr Nuclear Antigen 1 Essential for DNA Recognition and Pathogenesis. Front Mol Biosci 2021; 8:664436. [PMID: 34268333 PMCID: PMC8275655 DOI: 10.3389/fmolb.2021.664436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022] Open
Abstract
Epstein-Barr Virus (EBV) is considered the most important human pathogen due to its role in infections and cellular malignancies. It has been reported that this Oncolytic virus infects 90% world’s population. EBNA1 is required for DNA binding and survival of the virus and is considered an essential drug target. The biochemical and structural properties of this protein are known, but it is still unclear which residues impart a critical role in the recognition of dsDNA. Intending to disclose only the essential residues in recognition of dsDNA, this study used a computational pipeline to generate an alanine mutant of each interacting residue and determine the impact on the binding. Our analysis revealed that R469A, K514A, Y518A, R521A and R522A are the key hotspots for the recognition of dsDNA by the EBNA1. The dynamics properties, i.e. stability, flexibility, structural compactness, hydrogen bonding frequency, binding affinity, are altered by disrupting the protein-DNA contacts, thereby decreases the binding affinity. In particular, the two arginine substitution, R521A and R522A, significantly affected the total binding energy. Thus, we hypothesize that these residues impart a critical role in the dsDNA recognition and pathogenesis. This study would help to design structure-based drugs against the EBV infections.
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Affiliation(s)
| | - Muhammad Waseem
- Faculty of Rehabilitation and Allied Health Science, Riphah International University, Islamabad, Pakistan
| | - Syed Shujait Ali
- Center for Biotechnology and Microbiology, University of Swat, Swat, Pakistan
| | - Zahid Hussain
- Center for Biotechnology and Microbiology, University of Swat, Swat, Pakistan
| | - Kaoshan Chen
- College of Life Sciences, Shandong University, Jinan, China
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9
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KSHV-specific antivirals targeting the protein-DNA interaction of the latency-associated nuclear antigen. Future Med Chem 2021; 13:1141-1151. [PMID: 34036806 DOI: 10.4155/fmc-2021-0059] [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: 11/17/2022] Open
Abstract
The Kaposi sarcoma-associated herpesvirus (KSHV) is an oncogenic human herpesviruses that is responsible for cancer, especially in immunosuppressed people, such as patients with AIDS. So far, there are no KSHV-specifc antiviral agents available. In this review, we provide an overview on one particular target-centered approach toward novel anti-KSHV drugs focusing on interfering with the molecular functions of the latency-associated nuclear antigen (LANA). This review focuses on attempts to interfere with the LANA-DNA interaction mediated by the C-terminal domain. We describe the drug discovery approaches chosen for this endeavor as well as molecular structures that were identified in this innovative concept toward novel and KSHV-specific antiherpesviral agents.
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10
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Calderon A, Soldan SS, De Leo A, Deng Z, Frase DM, Anderson EM, Zhang Y, Vladimirova O, Lu F, Leung JC, Murphy ME, Lieberman PM. Identification of Mubritinib (TAK 165) as an inhibitor of KSHV driven primary effusion lymphoma via disruption of mitochondrial OXPHOS metabolism. Oncotarget 2020; 11:4224-4242. [PMID: 33245718 PMCID: PMC7679036 DOI: 10.18632/oncotarget.27815] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 10/29/2020] [Indexed: 02/07/2023] Open
Abstract
KSHV-associated cancers have poor prognoses and lack therapeutics that selectively target viral gene functions. We developed a screening campaign to identify known drugs that could be repurposed for the treatment of KSHV-associated cancers. We focused on primary effusion lymphoma (PEL), which has particularly poor treatment outcomes. We developed a luciferase reporter assay to test the ability of drugs to inhibit DNA binding of the KSHV LANA DNA binding domain (DBD). In parallel, we screened drugs for selective inhibition of a KSHV+ PEL cells. While potent hits were identified in each assay, only one hit, Mubritinib, was found to score in both assays. Mubritinib caused PEL cells to undergo cell cycle arrest with accumulation of sub-G1 population and Annexin V. Mubritinib inhibited LANA binding to KSHV terminal repeat (TR) DNA in KSHV+ PEL cells, but did not lead to KSHV lytic cycle reactivation. Mubritinib was originally identified as a receptor tyrosine kinase (RTK) inhibitor selective for HER2/ErbB2. But recent studies have revealed that Mubritinib can also inhibit the electron transport chain (ETC) complex at nanomolar concentrations. We found that other related ETC complex inhibitors (Rotenone and Deguelin) exhibited PEL cell growth inhibition while RTK inhibitors failed. Seahorse analysis demonstrated that Mubritinib selectively inhibits the maximal oxygen consumption (OCR) in PEL cells and metabolomics revealed changes in ATP/ADP and ATP/AMP ratios. These findings indicate that PEL cells are selectively sensitive to ETC complex inhibitors and provide a rationale for repurposing Mubritinib for selective treatment of PEL.
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Affiliation(s)
| | | | | | - Zhong Deng
- The Wistar Institute, Philadelphia, PA 19146, USA
| | | | | | - Yue Zhang
- The Wistar Institute, Philadelphia, PA 19146, USA
| | | | - Fang Lu
- The Wistar Institute, Philadelphia, PA 19146, USA
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11
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Lotke R, Schneeweiß U, Pietrek M, Günther T, Grundhoff A, Weidner-Glunde M, Schulz TF. Brd/BET Proteins Influence the Genome-Wide Localization of the Kaposi's Sarcoma-Associated Herpesvirus and Murine Gammaherpesvirus Major Latency Proteins. Front Microbiol 2020; 11:591778. [PMID: 33193257 PMCID: PMC7642799 DOI: 10.3389/fmicb.2020.591778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/28/2020] [Indexed: 01/22/2023] Open
Abstract
The rhadinoviruses Kaposi’s Sarcoma-associated herpesvirus (KSHV) and murine gammaherpesvirus (MHV-68) persist in infected hosts in a latent state that is characterized by the absence of virus production and by restricted viral gene expression. Their major latency protein, the latency-associated nuclear antigen (kLANA for KSHV and mLANA for MHV-68), is essential for viral genome maintenance and replication and involved in transcriptional regulation. Both kLANA and mLANA interact with cellular chromatin-associated proteins, among them the Bromodomain and Extra Terminal domain (Brd/BET) proteins, which recruit cellular and viral proteins to acetylated histones through their bromodomains and modulate cellular gene expression. Brd/BET proteins also play a role in the tethering, replication, segregation or integration of a diverse group of viral DNA genomes. In this study we explored if Brd/BET proteins influence the localization of the LANAs to preferential regions in the host chromatin and thereby contribute to kLANA- or mLANA-mediated transcriptional regulation. Using ChIP-Seq, we revealed a genome-wide co-enrichment of kLANA with Brd2/4 near cellular and viral transcriptional start sites (TSS). Treatment with I-BET151, an inhibitor of Brd/BET, displaced kLANA and Brd2/4 from TSS in the viral and host chromatin, but did not affect the direct binding of kLANA to kLANA-binding sites (LBS) in the KSHV latent origin of replication. Similarly, mLANA, but not a mLANA mutant deficient for binding to Brd2/4, also associated with cellular TSS. We compared the transcriptome of KSHV-infected with uninfected and kLANA-expressing human B cell lines, as well as a murine B cell line expressing mLANA or a Brd2/4-binding deficient mLANA mutant. We found that only a minority of cellular genes, whose TSS are occupied by kLANA or mLANA, is transcriptionally regulated by these latency proteins. Our findings extend previous reports on a preferential deposition of kLANA on cellular TSS and show that this characteristic chromatin association pattern is at least partially determined by the interaction of these viral latency proteins with members of the Brd/BET family of chromatin modulators.
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Affiliation(s)
- Rishikesh Lotke
- Institut für Virologie, Medizinische Hochschule Hannover, Hanover, Germany.,German Center for Infection Research, Hannover-Braunschweig and Hamburg Sites, Hanover, Germany
| | - Ulrike Schneeweiß
- Institut für Virologie, Medizinische Hochschule Hannover, Hanover, Germany
| | - Marcel Pietrek
- Institut für Virologie, Medizinische Hochschule Hannover, Hanover, Germany
| | - Thomas Günther
- Heinrich-Pette-Institut, Leibniz-Institut für Experimentelle Virologie, Hamburg, Germany
| | - Adam Grundhoff
- German Center for Infection Research, Hannover-Braunschweig and Hamburg Sites, Hanover, Germany.,Heinrich-Pette-Institut, Leibniz-Institut für Experimentelle Virologie, Hamburg, Germany
| | - Magdalena Weidner-Glunde
- Institut für Virologie, Medizinische Hochschule Hannover, Hanover, Germany.,German Center for Infection Research, Hannover-Braunschweig and Hamburg Sites, Hanover, Germany
| | - Thomas F Schulz
- Institut für Virologie, Medizinische Hochschule Hannover, Hanover, Germany.,German Center for Infection Research, Hannover-Braunschweig and Hamburg Sites, Hanover, Germany
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12
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KSHV LANA acetylation-selective acidic domain reader sequence mediates virus persistence. Proc Natl Acad Sci U S A 2020; 117:22443-22451. [PMID: 32820070 PMCID: PMC7486799 DOI: 10.1073/pnas.2004809117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Viruses modulate biochemical cellular pathways to permit infection. A recently described mechanism mediates selective protein interactions between acidic domain readers and unacetylated, lysine-rich regions, opposite of bromodomain function. Kaposi´s sarcoma (KS)-associated herpesvirus (KSHV) is tightly linked with KS, primary effusion lymphoma, and multicentric Castleman's disease. KSHV latently infects cells, and its genome persists as a multicopy, extrachromosomal episome. During latency, KSHV expresses a small subset of genes, including the latency-associated nuclear antigen (LANA), which mediates viral episome persistence. Here we show that LANA contains two tandem, partially overlapping, acidic domain sequences homologous to the SET oncoprotein acidic domain reader. This domain selectively interacts with unacetylated p53, as evidenced by reduced LANA interaction after overexpression of CBP, which acetylates p53, or with an acetylation mimicking carboxyl-terminal domain p53 mutant. Conversely, the interaction of LANA with an acetylation-deficient p53 mutant is enhanced. Significantly, KSHV LANA mutants lacking the acidic domain reader sequence are deficient for establishment of latency and persistent infection. This deficiency was confirmed under physiological conditions, on infection of mice with a murine gammaherpesvirus 68 chimera expressing LANA, where the virus was highly deficient in establishing latent infection in germinal center B cells. Therefore, LANA's acidic domain reader is critical for viral latency. These results implicate an acetylation-dependent mechanism mediating KSHV persistence and expand the role of acidic domain readers.
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13
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Ercan S, Şenses Y. Design and molecular docking studies of new inhibitor candidates for EBNA1 DNA binding site: a computational study. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2019.1709638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Selami Ercan
- Department of Nursing, School of Health Sciences, Batman University, Batman, Turkey
| | - Yusuf Şenses
- Institute of Science, Batman University, Batman, Turkey
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14
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Abstract
Persistent viral infections require a host cell reservoir that maintains functional copies of the viral genome. To this end, several DNA viruses maintain their genomes as extrachromosomal DNA minichromosomes in actively dividing cells. These viruses typically encode a viral protein that binds specifically to viral DNA genomes and tethers them to host mitotic chromosomes, thus enabling the viral genomes to hitchhike or piggyback into daughter cells. Viruses that use this tethering mechanism include papillomaviruses and the gammaherpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus. This review describes the advantages and consequences of persistent extrachromosomal viral genome replication.
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Affiliation(s)
- Tami L Coursey
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Alison A McBride
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA;
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15
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Minichromosome Maintenance Proteins Cooperate with LANA during the G 1/S Phase of the Cell Cycle To Support Viral DNA Replication. J Virol 2019; 93:JVI.02256-18. [PMID: 30651368 DOI: 10.1128/jvi.02256-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 01/13/2019] [Indexed: 12/11/2022] Open
Abstract
Latency-associated nuclear antigen (LANA) is essential for maintaining the viral genome by regulating replication and segregation of the viral episomes. The virus maintains 50 to 100 episomal copies during latency and replicates in synchrony with the cellular DNA of the infected cells. Since virus lacks its own replication machinery, it utilizes the cellular proteins for replication and maintenance, and LANA has been shown to make many of these proteins available for replication by directly recruiting them to the viral origin of replication within the terminal repeat (TR) region. Our studies identified members of the minichromosome maintenance (MCM) complex as potential LANA-interacting proteins. Here, we show that LANA specifically interacts with the components of the MCM complex, primarily during the G1/S phase of the cell cycle. MCM3 and -4 of the MCM complex specifically bound to the amino-terminal domain, while MCM6 bound to both the amino- and carboxyl-terminal domains of LANA. The MCM binding region in the N-terminal domain mapped to the chromatin binding domain (CBD). LANA with point mutations in the carboxyl-terminal domain identified an MCM6 binding domain, and overexpression of that domain (amino acids [aa] 1100 to 1150) abolished TR replication. Introduction of a peptide encompassing the LANA aa 1104 to 1123 reduced MCM6 association with LANA and TR replication. Moreover, a recombinant Kaposi's sarcoma-associated herpesvirus (KSHV) expressing LANA with a deletion of aa 1100 to 1150 (BAC16Δ1100-1150, where BAC is bacmid) showed reduced replication and persistence of viral genome copies compared to levels with the wild-type BAC16. Additionally, the role of MCMs in viral replication was confirmed by depleting MCMs and assaying transient and long-term maintenance of the viral episomes. The recruitment of MCMs to the replication origins through LANA was demonstrated through chromatin immunoprecipitation and isolation of proteins on nascent replicated DNA (iPOND). These data clearly show the role of MCMs in latent DNA replication and the potential for targeting the C-terminal domain of LANA to block viral persistence.IMPORTANCE LANA-mediated latent DNA replication is essential for efficient maintenance of KSHV episomes in the host. During latency, virus relies on the host cellular machinery for replication, which occurs in synchrony with the cellular DNA. LANA interacts with the components of multiple cellular pathways, including cellular replication machinery, and recruits them to the viral origin for DNA replication. In this study, we characterize the interactions between LANA and minichromosome maintenance (MCM) proteins, members of the cellular replication complex. We demonstrated a cell cycle-dependent interaction between LANA and MCMs and determined their importance for viral genome replication and maintenance through biochemical assays. In addition, we mapped a 50-amino acid region in LANA which was capable of abrogating the association of MCM6 with LANA and blocking DNA replication. We also detected LANA along with MCMs at the replication forks using a novel approach, isolation of proteins on nascent DNA (iPOND).
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16
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Kaposi's Sarcoma-Associated Herpesvirus LANA-Adjacent Regions with Distinct Functions in Episome Segregation or Maintenance. J Virol 2019; 93:JVI.02158-18. [PMID: 30626680 PMCID: PMC6401465 DOI: 10.1128/jvi.02158-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 01/02/2019] [Indexed: 12/16/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) is a 1,162-amino-acid protein that mediates episome persistence of viral genomes. LANA binds the KSHV terminal-repeat (TR) sequence through its carboxy-terminal domain to mediate DNA replication. LANA simultaneously binds mitotic chromosomes and TR DNA to segregate virus genomes to daughter cell nuclei. Amino-terminal LANA attaches to chromosomes by binding histones H2A/H2B, and carboxy-terminal LANA contributes to mitotic-chromosome binding. Although amino- and carboxy-terminal LANA are essential for episome persistence, they are not sufficient, since deletion of all internal LANA sequence renders LANA highly deficient for episome maintenance. Internal LANA sequence upstream of the internal repeat elements contributes to episome segregation and persistence. Here, we investigate this region with a panel of LANA deletion mutants. Mutants retained the ability to associate with mitotic chromosomes and bind TR DNA. In contrast to prior results, deletion of most of this sequence did not reduce LANA's ability to mediate DNA replication. Deletions of upstream sequence within the region compromised segregation of TR DNA to daughter cells, as assessed by retention of green fluorescent protein (GFP) expression from a replication-deficient TR plasmid. However, deletion of this upstream sequence did not reduce episome maintenance. In contrast, deletions that included an 80-amino-acid sequence immediately downstream resulted in highly deficient episome persistence. LANA with this downstream sequence deleted maintained the ability to replicate and segregate TR DNA, suggesting a unique role for the residues. Therefore, this work identifies adjacent LANA regions with distinct roles in episome segregation and persistence.IMPORTANCE KSHV LANA mediates episomal persistence of viral genomes. LANA binds the KSHV terminal-repeat (TR) sequence to mediate DNA replication and tethers KSHV DNA to mitotic chromosomes to segregate genomes to daughter cell nuclei. Here, we investigate LANA sequence upstream of the internal repeat elements that contributes to episome segregation and persistence. Mutants with deletions within this sequence maintained the ability to bind mitotic chromosomes or bind and replicate TR DNA. Deletion of upstream sequence within the region reduced segregation of TR DNA to daughter cells, but not episome maintenance. In contrast, mutants with deletions of 80 amino acids immediately downstream were highly deficient for episome persistence yet maintained the ability to replicate and segregate TR DNA, the two principal components of episome persistence, suggesting another role for the residues. In summary, this work identifies adjacent LANA sequence with distinct roles in episome segregation and persistence.
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17
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Epstein-Barr virus enhances genome maintenance of Kaposi sarcoma-associated herpesvirus. Proc Natl Acad Sci U S A 2018; 115:E11379-E11387. [PMID: 30429324 DOI: 10.1073/pnas.1810128115] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Primary effusion lymphoma (PEL) is a B cell lymphoma that is always associated with Kaposi's sarcoma-associated herpesvirus (KSHV) and in many cases also with Epstein-Barr virus (EBV); however, the requirement for EBV coinfection is not clear. Here, we demonstrate that adding exogenous EBV to KSHV+ single-positive PEL leads to increased KSHV genome maintenance and KSHV latency-associated nuclear antigen (LANA) expression. To show that EBV was necessary for naturally coinfected PEL, we nucleofected KSHV+/EBV+ PEL cell lines with an EBV-specific CRISPR/Cas9 plasmid to delete EBV and observed a dramatic decrease in cell viability, KSHV genome copy number, and LANA expression. This phenotype was reversed by expressing Epstein-Barr nuclear antigen 1 (EBNA-1) in trans, even though EBNA-1 and LANA do not colocalize in infected cells. This work reveals that EBV EBNA-1 plays an essential role in the pathogenesis of PEL by increasing KSHV viral load and LANA expression.
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18
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Duffy DJ, Schnitzler C, Karpinski L, Thomas R, Whilde J, Eastman C, Yang C, Krstic A, Rollinson D, Zirkelbach B, Yetsko K, Burkhalter B, Martindale MQ. Sea turtle fibropapilloma tumors share genomic drivers and therapeutic vulnerabilities with human cancers. Commun Biol 2018; 1:63. [PMID: 30271945 PMCID: PMC6123702 DOI: 10.1038/s42003-018-0059-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 04/26/2018] [Indexed: 12/31/2022] Open
Abstract
Wildlife populations are under intense anthropogenic pressures, with the geographic range of many species shrinking, dramatic reductions in population numbers and undisturbed habitats, and biodiversity loss. It is postulated that we are in the midst of a sixth (Anthropocene) mass extinction event, the first to be induced by human activity. Further, threatening vulnerable species is the increased rate of emerging diseases, another consequence of anthropogenic activities. Innovative approaches are required to help maintain healthy populations until the chronic underlying causes of these issues can be addressed. Fibropapillomatosis in sea turtles is one such wildlife disease. Here, we applied precision-medicine-based approaches to profile fibropapillomatosis tumors to better understand their biology, identify novel therapeutics, and gain insights into viral and environmental triggers for fibropapillomatosis. We show that fibropapillomatosis tumors share genetic vulnerabilities with human cancer types, revealing that they are amenable to treatment with human anti-cancer therapeutics. David Duffy et al. use a precision-medicine-based approach to study fibropapillomatosis tumors in sea turtles to identify environmental triggers and potential therapeutics. They show that these tumors share genetic similarities with human cancer types, and may be treatable using human anti-cancer therapies.
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Affiliation(s)
- David J Duffy
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA. .,Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK. .,Department of Biological Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
| | - Christine Schnitzler
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA.,Department of Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Lorraine Karpinski
- The Turtle Hospital, 2396 Overseas Highway, Marathon, FL, 33050, USA.,Pinecrest Veterinary Hospital, 12125 South Dixie Highway, Pinecrest, FL, 33156, USA
| | - Rachel Thomas
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Jenny Whilde
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Catherine Eastman
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Calvin Yang
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Aleksandar Krstic
- Systems Biology Ireland, School of Medicine, University College Dublin, Belfield, Dublin, 4, Ireland
| | - Devon Rollinson
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Bette Zirkelbach
- The Turtle Hospital, 2396 Overseas Highway, Marathon, FL, 33050, USA
| | - Kelsey Yetsko
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Brooke Burkhalter
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA
| | - Mark Q Martindale
- The Whitney Laboratory for Marine Bioscience, Sea Turtle Hospital, University of Florida, St. Augustine, FL, 32080, USA.,Department of Biology, University of Florida, Gainesville, FL, 32611, USA
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19
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Visualization of molecular biology: The LANA tether. Proc Natl Acad Sci U S A 2018; 115:4816-4818. [DOI: 10.1073/pnas.1804797115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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20
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Abstract
The human tumor viruses that replicate as plasmids (we use the term plasmid to avoid any confusion in the term episome, which was coined to mean DNA elements that occur both extrachromosomally and as integrated forms during their life cycles, as does phage lambda) share many features in their DNA synthesis. We know less about their mechanisms of maintenance in proliferating cells, but these mechanisms must underlie their partitioning to daughter cells. One amazing implication of how these viruses are thought to maintain themselves is that while host chromosomes commit themselves to partitioning in mitosis, these tumor viruses would commit themselves to partitioning before mitosis and probably in S phase shortly after their synthesis.
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21
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Superresolution microscopy reveals structural mechanisms driving the nanoarchitecture of a viral chromatin tether. Proc Natl Acad Sci U S A 2018; 115:4992-4997. [PMID: 29610353 DOI: 10.1073/pnas.1721638115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
By tethering their circular genomes (episomes) to host chromatin, DNA tumor viruses ensure retention and segregation of their genetic material during cell divisions. Despite functional genetic and crystallographic studies, there is little information addressing the 3D structure of these tethers in cells, issues critical for understanding persistent infection by these viruses. Here, we have applied direct stochastic optical reconstruction microscopy (dSTORM) to establish the nanoarchitecture of tethers within cells latently infected with the oncogenic human pathogen, Kaposi's sarcoma-associated herpesvirus (KSHV). Each KSHV tether comprises a series of homodimers of the latency-associated nuclear antigen (LANA) that bind with their C termini to the tandem array of episomal terminal repeats (TRs) and with their N termini to host chromatin. Superresolution imaging revealed that individual KSHV tethers possess similar overall dimensions and, in aggregate, fold to occupy the volume of a prolate ellipsoid. Using plasmids with increasing numbers of TRs, we found that tethers display polymer power law scaling behavior with a scaling exponent characteristic of active chromatin. For plasmids containing a two-TR tether, we determined the size, separation, and relative orientation of two distinct clusters of bound LANA, each corresponding to a single TR. From these data, we have generated a 3D model of the episomal half of the tether that integrates and extends previously established findings from epifluorescent, crystallographic, and epigenetic approaches. Our findings also validate the use of dSTORM in establishing novel structural insights into the physical basis of molecular connections linking host and pathogen genomes.
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22
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Full-Length Isoforms of Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Accumulate in the Cytoplasm of Cells Undergoing the Lytic Cycle of Replication. J Virol 2017; 91:JVI.01532-17. [PMID: 28978712 DOI: 10.1128/jvi.01532-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/29/2017] [Indexed: 01/09/2023] Open
Abstract
The latency-associated nuclear antigen (LANA) of the Kaposi's sarcoma-associated herpesvirus (KSHV) performs a variety of functions to establish and maintain KSHV latency. During latency, LANA localizes to discrete punctate spots in the nucleus, where it tethers viral episomes to cellular chromatin and interacts with nuclear components to regulate cellular and viral gene expression. Using highly sensitive tyramide signal amplification, we determined that LANA localizes to the cytoplasm in different cell types undergoing the lytic cycle of replication after de novo primary infection and after spontaneous, tetradecanoyl phorbol acetate-, or open reading frame 50 (ORF50)/replication transactivator (RTA)-induced activation. We confirmed the presence of cytoplasmic LANA in a subset of cells in lytically active multicentric Castleman disease lesions. The induction of cellular migration by scratch-wounding confluent cell cultures, culturing under subconfluent conditions, or induction of cell differentiation in primary cultures upregulated the number of cells permissive for primary lytic KSHV infection. The induction of lytic replication was characterized by high-level expression of cytoplasmic LANA and nuclear ORF59, a marker of lytic replication. Subcellular fractionation studies revealed the presence of multiple isoforms of LANA in the cytoplasm of ORF50/RTA-activated Vero cells undergoing primary infection. Mass spectrometry analysis demonstrated that cytoplasmic LANA isoforms were full length, containing the N-terminal nuclear localization signal. These results suggest that trafficking of LANA to different subcellular locations is a regulated phenomenon, which allows LANA to interact with cellular components in different compartments during both the latent and the replicative stages of the KSHV life cycle.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) causes AIDS-related malignancies, including lymphomas and Kaposi's sarcoma. KSHV establishes lifelong infections using its latency-associated nuclear antigen (LANA). During latency, LANA localizes to the nucleus, where it connects viral and cellular DNA complexes and regulates gene expression, allowing the virus to maintain long-term infections. Our research shows that intact LANA traffics to the cytoplasm of cells undergoing permissive lytic infections and latently infected cells in which the virus is induced to replicate. This suggests that LANA plays important roles in the cytoplasm and nuclear compartments of the cell during different stages of the KSHV life cycle. Determining cytoplasmic function and mechanism for regulation of the nuclear localization of LANA will enhance our understanding of the biology of this virus, leading to therapeutic approaches to eliminate infection and block its pathological effects.
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23
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Habison AC, de Miranda MP, Beauchemin C, Tan M, Cerqueira SA, Correia B, Ponnusamy R, Usherwood EJ, McVey CE, Simas JP, Kaye KM. Cross-species conservation of episome maintenance provides a basis for in vivo investigation of Kaposi's sarcoma herpesvirus LANA. PLoS Pathog 2017; 13:e1006555. [PMID: 28910389 PMCID: PMC5599060 DOI: 10.1371/journal.ppat.1006555] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/27/2017] [Indexed: 12/26/2022] Open
Abstract
Many pathogens, including Kaposi's sarcoma herpesvirus (KSHV), lack tractable small animal models. KSHV persists as a multi-copy, nuclear episome in latently infected cells. KSHV latency-associated nuclear antigen (kLANA) binds viral terminal repeat (kTR) DNA to mediate episome persistence. Model pathogen murine gammaherpesvirus 68 (MHV68) mLANA acts analogously on mTR DNA. kLANA and mLANA differ substantially in size and kTR and mTR show little sequence conservation. Here, we find kLANA and mLANA act reciprocally to mediate episome persistence of TR DNA. Further, kLANA rescued mLANA deficient MHV68, enabling a chimeric virus to establish latent infection in vivo in germinal center B cells. The level of chimeric virus in vivo latency was moderately reduced compared to WT infection, but WT or chimeric MHV68 infected cells had similar viral genome copy numbers as assessed by immunofluorescence of LANA intranuclear dots or qPCR. Thus, despite more than 60 Ma of evolutionary divergence, mLANA and kLANA act reciprocally on TR DNA, and kLANA functionally substitutes for mLANA, allowing kLANA investigation in vivo. Analogous chimeras may allow in vivo investigation of genes of other human pathogens.
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Affiliation(s)
- Aline C. Habison
- Departments of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marta Pires de Miranda
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Chantal Beauchemin
- Departments of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Min Tan
- Departments of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sofia A. Cerqueira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Bruno Correia
- Instituto de Tecnologia Quimica e Bioliogica Antonio Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Rajesh Ponnusamy
- Instituto de Tecnologia Quimica e Bioliogica Antonio Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Edward J. Usherwood
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America
| | - Colin E. McVey
- Instituto de Tecnologia Quimica e Bioliogica Antonio Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - J. Pedro Simas
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (KMK); (JPS)
| | - Kenneth M. Kaye
- Departments of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (KMK); (JPS)
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The Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus Inhibits Expression of SUMO/Sentrin-Specific Peptidase 6 To Facilitate Establishment of Latency. J Virol 2017; 91:JVI.00806-17. [PMID: 28615201 DOI: 10.1128/jvi.00806-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 05/15/2017] [Indexed: 11/20/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), which belongs to the Gammaherpesviridae, typically displays two different phases in its life cycle, the latent phase and the lytic phase. Latency-associated nuclear antigen (LANA), the primary viral product during latency, has been reported to bind to a series of cellular gene promoters to modulate gene transcription. To systemically elucidate the cellular genes regulated by LANA, we identified genome-wide LANA binding sites by chromatin immunoprecipitation coupled with sequencing (ChIP-seq). We stratified ChIP-seq data and found that LANA might be involved in the macromolecule catabolic process. Specifically, we found and verified that LANA could directly bind to the promoter of the SUMO/sentrin-specific peptidase 6 (SENP6) gene in vivo and in vitro LANA could repress SENP6 promoter activity in a dose-dependent manner in a reporter gene assay. LANA expression was sufficient to inhibit endogenous SENP6 expression at both the RNA and protein levels. Moreover, SENP6 overexpression in KSHV-infected cells reduced LANA at the protein level. Mechanistically, we found that SENP6 could interact with LANA and reduce the formation of sumoylated LANA, which relies on the desumoylation ability of SENP6. During de novo infection, SENP6 overexpression would decrease the abundance of LANA and enhance viral gene expression, which would hamper the establishment of latency. Taken together, these data suggest that KSHV-encoded LANA could inhibit SENP6 expression to regulate the abundance of itself, which may play an important role in controlling the establishment of latency.IMPORTANCE LANA, as a key latent protein produced by KSHV, is responsible for episome persistence and regulates viral reactivation. In the present study, our results demonstrated that LANA could bind to the promoter region of the SENP6 gene and inhibit SENP6 expression while the regulated SENP6 could in turn modulate the abundance of LANA through desumoylation. This delicate regulation may provide important insights to explain the abundance of LANA during KSHV latency.
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Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen: Replicating and Shielding Viral DNA during Viral Persistence. J Virol 2017; 91:JVI.01083-16. [PMID: 28446671 DOI: 10.1128/jvi.01083-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Kaposi's sarcoma herpesvirus (KSHV) establishes lifelong latency. The viral latency-associated nuclear antigen (LANA) promotes viral persistence by tethering the viral genome to cellular chromosomes and by participating in latent DNA replication. Recently, the structure of the LANA C-terminal DNA binding domain was solved and new cytoplasmic variants of LANA were discovered. We discuss how these findings contribute to our current view of LANA structure and assembly and of its role during viral persistence.
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Lomonte P. Herpesvirus Latency: On the Importance of Positioning Oneself. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2017; 223:95-117. [PMID: 28528441 DOI: 10.1007/978-3-319-53168-7_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The nucleus is composed of multiple compartments and domains, which directly or indirectly influence many cellular processes including gene expression, RNA splicing and maturation, protein post-translational modifications, and chromosome segregation. Nuclear-replicating viruses, especially herpesviruses, have co-evolved with the cell, adopting strategies to counteract and eventually hijack this hostile environment for their own benefit. This allows them to persist in the host for the entire life of an individual and to ensure their maintenance in the target species. Herpesviruses establish latency in dividing or postmitotic cells from which they can efficiently reactivate after sometimes years of a seemingly dormant state. Therefore, herpesviruses circumvent the threat of permanent silencing by reactivating their dormant genomes just enough to escape extinction, but not too much to avoid life-threatening damage to the host. In addition, herpesviruses that establish latency in dividing cells must adopt strategies to maintain their genomes in the daughter cells to avoid extinction by dilution of their genomes following multiple cell divisions. From a biochemical point of view, reactivation and maintenance of viral genomes in dividing cells occur successfully because the viral genomes interact with the nuclear architecture in a way that allows the genomes to be transmitted faithfully and to benefit from the nuclear micro-environments that allow reactivation following specific stimuli. Therefore, spatial positioning of the viral genomes within the nucleus is likely to be essential for the success of the latent infection and, beyond that, for the maintenance of herpesviruses in their respective hosts.
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Affiliation(s)
- Patrick Lomonte
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5310, INSERM U-1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Assembly, Nuclear Domains, Virus, 69008, Lyon, France.
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Juillard F, Tan M, Li S, Kaye KM. Kaposi's Sarcoma Herpesvirus Genome Persistence. Front Microbiol 2016; 7:1149. [PMID: 27570517 PMCID: PMC4982378 DOI: 10.3389/fmicb.2016.01149] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/11/2016] [Indexed: 12/17/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) has an etiologic role in Kaposi’s sarcoma, primary effusion lymphoma, and multicentric Castleman’s disease. These diseases are most common in immunocompromised individuals, especially those with AIDS. Similar to all herpesviruses, KSHV infection is lifelong. KSHV infection in tumor cells is primarily latent, with only a small subset of cells undergoing lytic infection. During latency, the KSHV genome persists as a multiple copy, extrachromosomal episome in the nucleus. In order to persist in proliferating tumor cells, the viral genome replicates once per cell cycle and then segregates to daughter cell nuclei. KSHV only expresses several genes during latent infection. Prominent among these genes, is the latency-associated nuclear antigen (LANA). LANA is responsible for KSHV genome persistence and also exerts transcriptional regulatory effects. LANA mediates KSHV DNA replication and in addition, is responsible for segregation of replicated genomes to daughter nuclei. LANA serves as a molecular tether, bridging the viral genome to mitotic chromosomes to ensure that KSHV DNA reaches progeny nuclei. N-terminal LANA attaches to mitotic chromosomes by binding histones H2A/H2B at the surface of the nucleosome. C-terminal LANA binds specific KSHV DNA sequence and also has a role in chromosome attachment. In addition to the essential roles of N- and C-terminal LANA in genome persistence, internal LANA sequence is also critical for efficient episome maintenance. LANA’s role as an essential mediator of virus persistence makes it an attractive target for inhibition in order to prevent or treat KSHV infection and disease.
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Affiliation(s)
- Franceline Juillard
- Departments of Medicine, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
| | - Min Tan
- Departments of Medicine, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
| | - Shijun Li
- Departments of Medicine, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
| | - Kenneth M Kaye
- Departments of Medicine, Brigham and Women's Hospital, Harvard Medical School Boston, MA, USA
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Cytoplasmic isoforms of Kaposi sarcoma herpesvirus LANA recruit and antagonize the innate immune DNA sensor cGAS. Proc Natl Acad Sci U S A 2016; 113:E1034-43. [PMID: 26811480 DOI: 10.1073/pnas.1516812113] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The latency-associated nuclear antigen (LANA) of Kaposi sarcoma herpesvirus (KSHV) is mainly localized and functions in the nucleus of latently infected cells, playing a pivotal role in the replication and maintenance of latent viral episomal DNA. In addition, N-terminally truncated cytoplasmic isoforms of LANA, resulting from internal translation initiation, have been reported, but their function is unknown. Using coimmunoprecipitation and MS, we found the cGMP-AMP synthase (cGAS), an innate immune DNA sensor, to be a cellular interaction partner of cytoplasmic LANA isoforms. By directly binding to cGAS, LANA, and particularly, a cytoplasmic isoform, inhibit the cGAS-STING-dependent phosphorylation of TBK1 and IRF3 and thereby antagonize the cGAS-mediated restriction of KSHV lytic replication. We hypothesize that cytoplasmic forms of LANA, whose expression increases during lytic replication, inhibit cGAS to promote the reactivation of the KSHV from latency. This observation points to a novel function of the cytoplasmic isoforms of LANA during lytic replication and extends the function of LANA from its role during latency to the lytic replication cycle.
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Identification of Viral and Host Proteins That Interact with Murine Gammaherpesvirus 68 Latency-Associated Nuclear Antigen during Lytic Replication: a Role for Hsc70 in Viral Replication. J Virol 2015; 90:1397-413. [PMID: 26581985 DOI: 10.1128/jvi.02022-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/10/2015] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Latency-associated nuclear antigen (LANA) is a conserved, multifunctional protein encoded by members of the rhadinovirus subfamily of gammaherpesviruses, including Kaposi sarcoma-associated herpesvirus (KSHV) and murine gammaherpesvirus 68 (MHV68). We previously demonstrated that MHV68 LANA (mLANA) is required for efficient lytic replication. However, mechanisms by which mLANA facilitates viral replication, including interactions with cellular and viral proteins, are not known. Thus, we performed a mass spectrometry-based interaction screen that defined an mLANA protein-protein interaction network for lytic viral replication consisting of 15 viral proteins and 191 cellular proteins, including 19 interactions previously reported in KSHV LANA interaction studies. We also employed a stable-isotope labeling technique to illuminate high-priority mLANA-interacting host proteins. Among the top prioritized mLANA-binding proteins was a cellular chaperone, heat shock cognate protein 70 (Hsc70). We independently validated the mLANA-Hsc70 interaction through coimmunoprecipitation and in vitro glutathione S-transferase (GST) pulldown assays. Immunofluorescence and cellular fractionation analyses comparing wild-type (WT) to mLANA-null MHV68 infections demonstrated mLANA-dependent recruitment of Hsc70 to nuclei of productively infected cells. Pharmacologic inhibition and small hairpin RNA (shRNA)-mediated knockdown of Hsc70 impaired MHV68 lytic replication, which functionally correlated with impaired viral protein expression, reduced viral DNA replication, and failure to form viral replication complexes. Replication of mLANA-null MHV68 was less affected than that of WT virus by Hsc70 inhibition, which strongly suggests that Hsc70 function in MHV68 lytic replication is at least partially mediated by its interaction with mLANA. Together these experiments identify proteins engaged by mLANA during the MHV68 lytic replication cycle and define a previously unknown role for Hsc70 in facilitating MHV68 lytic replication. IMPORTANCE Latency-associated nuclear antigen (LANA) is a conserved gamma-2-herpesvirus protein important for latency maintenance and pathogenesis. For MHV68, this includes regulating lytic replication and reactivation. While previous studies of KSHV LANA defined interactions with host cell proteins that impact latency, interactions that facilitate productive viral replication are not known. Thus, we performed a differential proteomics analysis to identify and prioritize cellular and viral proteins that interact with the MHV68 LANA homolog during lytic infection. Among the proteins identified was heat shock cognate protein 70 (Hsc70), which we determined is recruited to host cell nuclei in an mLANA-dependent process. Moreover, Hsc70 facilitates MHV68 protein expression and DNA replication, thus contributing to efficient MHV68 lytic replication. These experiments expand the known LANA-binding proteins to include MHV68 lytic replication and demonstrate a previously unappreciated role for Hsc70 in regulating viral replication.
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Ponnusamy R, Petoukhov MV, Correia B, Custodio TF, Juillard F, Tan M, Pires de Miranda M, Carrondo MA, Simas JP, Kaye KM, Svergun DI, McVey CE. KSHV but not MHV-68 LANA induces a strong bend upon binding to terminal repeat viral DNA. Nucleic Acids Res 2015; 43:10039-54. [PMID: 26424851 PMCID: PMC4787769 DOI: 10.1093/nar/gkv987] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 09/16/2015] [Indexed: 12/20/2022] Open
Abstract
Latency-associated nuclear antigen (LANA) is central to episomal tethering, replication and transcriptional regulation of γ2-herpesviruses. LANA binds cooperatively to the terminal repeat (TR) region of the viral episome via adjacent LANA binding sites (LBS), but the molecular mechanism by which LANA assembles on the TR remains elusive. We show that KSHV LANA and MHV-68 LANA proteins bind LBS DNA using strikingly different modes. Solution structure of LANA complexes revealed that while kLANA tetramer is intrinsically bent both in the free and bound state to LBS1-2 DNA, mLANA oligomers instead adopt a rigid linear conformation. In addition, we report a novel non-ring kLANA structure that displays more flexibility at its assembly interface than previously demonstrated. We identified a hydrophobic pivot point located at the dimer-dimer assembly interface, which gives rotational freedom for kLANA to adopt variable conformations to accommodate both LBS1-2 and LBS2-1-3 DNA. Alterations in the arrangement of LBS within TR or at the tetramer assembly interface have a drastic effect on the ability of kLANA binding. We also show kLANA and mLANA DNA binding functions can be reciprocated. Although KSHV and MHV-68 are closely related, the findings provide new insights into how the structure, oligomerization, and DNA binding of LANA have evolved differently to assemble on the TR DNA.
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Affiliation(s)
- Rajesh Ponnusamy
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2700-157, Portugal
| | - Maxim V Petoukhov
- European Molecular Biology Laboratory, Hamburg Unit, EMBL c/o DESY, Hamburg 22607, Germany
| | - Bruno Correia
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2700-157, Portugal
| | - Tania F Custodio
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2700-157, Portugal
| | - Franceline Juillard
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Min Tan
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Marta Pires de Miranda
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Maria A Carrondo
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2700-157, Portugal
| | - J Pedro Simas
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Kenneth M Kaye
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Dmitri I Svergun
- European Molecular Biology Laboratory, Hamburg Unit, EMBL c/o DESY, Hamburg 22607, Germany
| | - Colin E McVey
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2700-157, Portugal
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31
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Li S, Tan M, Juillard F, Ponnusamy R, Correia B, Simas JP, Carrondo MA, McVey CE, Kaye KM. The Kaposi Sarcoma Herpesvirus Latency-associated Nuclear Antigen DNA Binding Domain Dorsal Positive Electrostatic Patch Facilitates DNA Replication and Episome Persistence. J Biol Chem 2015; 290:28084-28096. [PMID: 26420481 DOI: 10.1074/jbc.m115.674622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Indexed: 12/15/2022] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) has a causative role in several human malignancies. KSHV latency-associated nuclear antigen (LANA) mediates persistence of viral episomes in latently infected cells. LANA mediates KSHV DNA replication and segregates episomes to progeny nuclei. The structure of the LANA DNA binding domain was recently solved, revealing a positive electrostatic patch opposite the DNA binding surface, which is the site of BET protein binding. Here we investigate the functional role of the positive patch in LANA-mediated episome persistence. As expected, LANA mutants with alanine or glutamate substitutions in the central, peripheral, or lateral portions of the positive patch maintained the ability to bind DNA by EMSA. However, all of the substitution mutants were deficient for LANA DNA replication and episome maintenance. Mutation of the peripheral region generated the largest deficiencies. Despite these deficiencies, all positive patch mutants concentrated to dots along mitotic chromosomes in cells containing episomes, similar to LANA. The central and peripheral mutants, but not the lateral mutants, were reduced for BET protein interaction as assessed by co-immunoprecipitation. However, defects in BET protein binding were independent of episome maintenance function. Overall, the reductions in episome maintenance closely correlated with DNA replication deficiencies, suggesting that the replication defects account for the reduced episome persistence. Therefore, the electrostatic patch exerts a key role in LANA-mediated DNA replication and episome persistence and may act through a host cell partner(s) other than a BET protein or by inducing specific structures or complexes.
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Affiliation(s)
- Shijun Li
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115
| | - Min Tan
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115
| | - Franceline Juillard
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115
| | - Rajesh Ponnusamy
- Instituto de Tecnologia Quimica e Biologica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Bruno Correia
- Instituto de Tecnologia Quimica e Biologica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - J Pedro Simas
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Maria A Carrondo
- Instituto de Tecnologia Quimica e Biologica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Colin E McVey
- Instituto de Tecnologia Quimica e Biologica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Kenneth M Kaye
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115.
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The 3D structure of Kaposi sarcoma herpesvirus LANA C-terminal domain bound to DNA. Proc Natl Acad Sci U S A 2015; 112:6694-9. [PMID: 25947153 DOI: 10.1073/pnas.1421804112] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kaposi sarcoma herpesvirus (KSHV) persists as a latent nuclear episome in dividing host cells. This episome is tethered to host chromatin to ensure proper segregation during mitosis. For duplication of the latent genome, the cellular replication machinery is recruited. Both of these functions rely on the constitutively expressed latency-associated nuclear antigen (LANA) of the virus. Here, we report the crystal structure of the KSHV LANA DNA-binding domain (DBD) in complex with its high-affinity viral target DNA, LANA binding site 1 (LBS1), at 2.9 Å resolution. In contrast to homologous proteins such as Epstein-Barr virus nuclear antigen 1 (EBNA-1) of the related γ-herpesvirus Epstein-Barr virus, specific DNA recognition by LANA is highly asymmetric. In addition to solving the crystal structure, we found that apart from the two known LANA binding sites, LBS1 and LBS2, LANA also binds to a novel site, denoted LBS3. All three sites are located in a region of the KSHV terminal repeat subunit previously recognized as a minimal replicator. Moreover, we show that the LANA DBD can coat DNA of arbitrary sequence by virtue of a characteristic lysine patch, which is absent in EBNA-1 of the Epstein-Barr virus. Likely, these higher-order assemblies involve the self-association of LANA into supermolecular spirals. One such spiral assembly was solved as a crystal structure of 3.7 Å resolution in the absence of DNA. On the basis of our data, we propose a model for the controlled nucleation of higher-order LANA oligomers that might contribute to the characteristic subnuclear KSHV microdomains ("LANA speckles"), a hallmark of KSHV latency.
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Uppal T, Jha HC, Verma SC, Robertson ES. Chromatinization of the KSHV Genome During the KSHV Life Cycle. Cancers (Basel) 2015; 7:112-42. [PMID: 25594667 PMCID: PMC4381254 DOI: 10.3390/cancers7010112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/07/2015] [Indexed: 12/18/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the gamma herpesvirus family and is the causative agent of various lymphoproliferative diseases in humans. KSHV, like other herpesviruses, establishes life-long latent infection with the expression of a limited number of viral genes. Expression of these genes is tightly regulated by both the viral and cellular factors. Recent advancements in identifying the expression profiles of viral transcripts, using tilling arrays and next generation sequencing have identified additional coding and non-coding transcripts in the KSHV genome. Determining the functions of these transcripts will provide a better understanding of the mechanisms utilized by KSHV in altering cellular pathways involved in promoting cell growth and tumorigenesis. Replication of the viral genome is critical in maintaining the existing copies of the viral episomes during both latent and lytic phases of the viral life cycle. The replication of the viral episome is facilitated by viral components responsible for recruiting chromatin modifying enzymes and replication factors for altering the chromatin complexity and replication initiation functions, respectively. Importantly, chromatin modification of the viral genome plays a crucial role in determining whether the viral genome will persist as latent episome or undergo lytic reactivation. Additionally, chromatinization of the incoming virion DNA, which lacks chromatin structure, in the target cells during primary infection, helps in establishing latent infection. Here, we discuss the recent advancements on our understating of KSHV genome chromatinization and the consequences of chromatin modifications on viral life cycle.
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Affiliation(s)
- Timsy Uppal
- Department of Microbiology and Immunology, School of Medicine, University of Nevada, 1664 N Virginia Street, MS 320, Reno, NV 89557, USA.
| | - Hem C Jha
- Department of Microbiology and the Tumor Virology Program of the Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, 201E Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104, USA.
| | - Subhash C Verma
- Department of Microbiology and Immunology, School of Medicine, University of Nevada, 1664 N Virginia Street, MS 320, Reno, NV 89557, USA.
| | - Erle S Robertson
- Department of Microbiology and the Tumor Virology Program of the Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, 201E Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104, USA.
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Hellert J, Krausze J, Schulz TF, Lührs T. Crystallization, room-temperature X-ray diffraction and preliminary analysis of Kaposi's sarcoma herpesvirus LANA bound to DNA. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2014; 70:1570-4. [PMID: 25372834 DOI: 10.1107/s2053230x14019906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 09/03/2014] [Indexed: 01/03/2023]
Abstract
The latency-associated nuclear antigen (LANA) is the latent origin-binding protein and chromatin anchor of the Kaposi's sarcoma herpesvirus (KSHV/HHV-8) genome. Its C-terminal domain (CTD) binds sequence-specifically to the viral origin of replication, whereas the N-terminal domain links it to nucleosomes of cellular chromatin for long-term persistence in dividing host cells. Here, the crystallization and X-ray data acquisition of a mutant LANA CTD in complex with its wild-type target DNA LBS1 is described. This report describes the rational protein engineering for successful co-crystallization with DNA and X-ray diffraction data collection at room temperature on the high-brilliance third-generation synchrotron PETRA III at DESY, Germany.
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Affiliation(s)
- Jan Hellert
- Department of Structural Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Joern Krausze
- Department of Structural Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Thomas F Schulz
- Institute of Virology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Thorsten Lührs
- Department of Structural Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
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35
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Chang PC, Kung HJ. SUMO and KSHV Replication. Cancers (Basel) 2014; 6:1905-24. [PMID: 25268162 PMCID: PMC4276950 DOI: 10.3390/cancers6041905] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/09/2014] [Accepted: 09/10/2014] [Indexed: 02/07/2023] Open
Abstract
Small Ubiquitin-related MOdifier (SUMO) modification was initially identified as a reversible post-translational modification that affects the regulation of diverse cellular processes, including signal transduction, protein trafficking, chromosome segregation, and DNA repair. Increasing evidence suggests that the SUMO system also plays an important role in regulating chromatin organization and transcription. It is thus not surprising that double-stranded DNA viruses, such as Kaposi's sarcoma-associated herpesvirus (KSHV), have exploited SUMO modification as a means of modulating viral chromatin remodeling during the latent-lytic switch. In addition, SUMO regulation allows the disassembly and assembly of promyelocytic leukemia protein-nuclear bodies (PML-NBs), an intrinsic antiviral host defense, during the viral replication cycle. Overcoming PML-NB-mediated cellular intrinsic immunity is essential to allow the initial transcription and replication of the herpesvirus genome after de novo infection. As a consequence, KSHV has evolved a way as to produce multiple SUMO regulatory viral proteins to modulate the cellular SUMO environment in a dynamic way during its life cycle. Remarkably, KSHV encodes one gene product (K-bZIP) with SUMO-ligase activities and one gene product (K-Rta) that exhibits SUMO-targeting ubiquitin ligase (STUbL) activity. In addition, at least two viral products are sumoylated that have functional importance. Furthermore, sumoylation can be modulated by other viral gene products, such as the viral protein kinase Orf36. Interference with the sumoylation of specific viral targets represents a potential therapeutic strategy when treating KSHV, as well as other oncogenic herpesviruses. Here, we summarize the different ways KSHV exploits and manipulates the cellular SUMO system and explore the multi-faceted functions of SUMO during KSHV's life cycle and pathogenesis.
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Affiliation(s)
- Pei-Ching Chang
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei 112, Taiwan.
| | - Hsing-Jien Kung
- Institute for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
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36
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Hu J, Yang Y, Turner PC, Jain V, McIntyre LM, Renne R. LANA binds to multiple active viral and cellular promoters and associates with the H3K4methyltransferase hSET1 complex. PLoS Pathog 2014; 10:e1004240. [PMID: 25033463 PMCID: PMC4102568 DOI: 10.1371/journal.ppat.1004240] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 05/27/2014] [Indexed: 02/07/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a γ-herpesvirus associated with KS and two lymphoproliferative diseases. Recent studies characterized epigenetic modification of KSHV episomes during latency and determined that latency-associated genes are associated with H3K4me3 while most lytic genes are associated with the silencing mark H3K27me3. Since the latency-associated nuclear antigen (LANA) (i) is expressed very early after de novo infection, (ii) interacts with transcriptional regulators and chromatin remodelers, and (iii) regulates the LANA and RTA promoters, we hypothesized that LANA may contribute to the establishment of latency through epigenetic control. We performed a detailed ChIP-seq analysis in cells of lymphoid and endothelial origin and compared H3K4me3, H3K27me3, polII, and LANA occupancy. On viral episomes LANA binding was detected at numerous lytic and latent promoters, which were transactivated by LANA using reporter assays. LANA binding was highly enriched at H3K4me3 peaks and this co-occupancy was also detected on many host gene promoters. Bioinformatic analysis of enriched LANA binding sites in combination with biochemical binding studies revealed three distinct binding patterns. A small subset of LANA binding sites showed sequence homology to the characterized LBS1/2 sequence in the viral terminal repeat. A large number of sites contained a novel LANA binding motif (TCCAT)3 which was confirmed by gel shift analysis. Third, some viral and cellular promoters did not contain LANA binding sites and are likely enriched through protein/protein interaction. LANA was associated with H3K4me3 marks and in PEL cells 86% of all LANA bound promoters were transcriptionally active, leading to the hypothesis that LANA interacts with the machinery that methylates H3K4. Co-immunoprecipitation demonstrated LANA association with endogenous hSET1 complexes in both lymphoid and endothelial cells suggesting that LANA may contribute to the epigenetic profile of KSHV episomes. KSHV is a DNA tumor virus which is associated with Kaposi's sarcoma and some lymphoproliferative diseases. During latent infection, the viral genome persists as circular extrachromosomal DNA in the nucleus and expresses a very limited number of viral proteins, including LANA, a multi-functional protein. KSHV viral episomes, like host genomic DNA, are subject to chromatin formation and histone modifications which contribute to tightly controlled gene expression during latency. We determined where LANA binds on the KSHV and human genomes, and mapped activating and repressing histone marks and RNA polymerase II binding. We found that LANA bound near transcription start sites, and binding correlated with the transcription active mark H3K4me3, but not silencing mark H3K27me3. Binding sites for transcription factors including znf143, CTCF, and Stat1 are enriched at regions where LANA is bound. We identified some LANA binding sites near human gene promoters that resembled KSHV sequences known to bind LANA. We also found a novel motif that occurs frequently in the human genome and that binds LANA directly despite being different from known LANA-binding sequences. Furthermore, we demonstrate that LANA associates with the H3K4 methyltransferase hSET1 which creates activating histone marks.
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Affiliation(s)
- Jianhong Hu
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
| | - Yajie Yang
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
| | - Peter C. Turner
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
| | - Vaibhav Jain
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
| | - Lauren M. McIntyre
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
- UF Genetics Institute, University of Florida, Gainesville, Florida, United States of America
| | - Rolf Renne
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
- UF Genetics Institute, University of Florida, Gainesville, Florida, United States of America
- UF Health Cancer Center, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Günther T, Schreiner S, Dobner T, Tessmer U, Grundhoff A. Influence of ND10 components on epigenetic determinants of early KSHV latency establishment. PLoS Pathog 2014; 10:e1004274. [PMID: 25033267 PMCID: PMC4102598 DOI: 10.1371/journal.ppat.1004274] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 06/05/2014] [Indexed: 12/15/2022] Open
Abstract
We have previously demonstrated that acquisition of intricate patterns of activating (H3K4me3, H3K9/K14ac) and repressive (H3K27me3) histone modifications is a hallmark of KSHV latency establishment. The precise molecular mechanisms that shape the latent histone modification landscape, however, remain unknown. Promyelocytic leukemia nuclear bodies (PML-NB), also called nuclear domain 10 (ND10), have emerged as mediators of innate immune responses that can limit viral gene expression via chromatin based mechanisms. Consequently, although ND10 functions thus far have been almost exclusively investigated in models of productive herpesvirus infection, it has been proposed that they also may contribute to the establishment of viral latency. Here, we report the first systematic study of the role of ND10 during KSHV latency establishment, and link alterations in the subcellular distribution of ND10 components to a temporal analysis of histone modification acquisition and host cell gene expression during the early infection phase. Our study demonstrates that KSHV infection results in a transient interferon response that leads to induction of the ND10 components PML and Sp100, but that repression by ND10 bodies is unlikely to contribute to KSHV latency establishment. Instead, we uncover an unexpected role for soluble Sp100 protein, which is efficiently and permanently relocalized from nucleoplasmic and chromatin-associated fractions into the insoluble matrix. We show that LANA expression is sufficient to induce Sp100 relocalization, likely via mediating SUMOylation of Sp100. Furthermore, we demonstrate that depletion of soluble Sp100 occurs precisely when repressive H3K27me3 marks first accumulate on viral genomes, and that knock-down of Sp100 (but not PML or Daxx) facilitates H3K27me3 acquisition. Collectively, our data support a model in which non-ND10 resident Sp100 acts as a negative regulator of polycomb repressive complex-2 (PRC2) recruitment, and suggest that KSHV may actively escape ND10 silencing mechanisms to promote establishment of latent chromatin.
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Affiliation(s)
- Thomas Günther
- Research Group Virus Genomics, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Sabrina Schreiner
- Research Unit Viral Transformation, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Thomas Dobner
- Research Unit Viral Transformation, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Uwe Tessmer
- Research Group Virus Genomics, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Adam Grundhoff
- Research Group Virus Genomics, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
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Tolani B, Gopalakrishnan R, Punj V, Matta H, Chaudhary PM. Targeting Myc in KSHV-associated primary effusion lymphoma with BET bromodomain inhibitors. Oncogene 2014; 33:2928-37. [PMID: 23792448 PMCID: PMC4892892 DOI: 10.1038/onc.2013.242] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 05/03/2013] [Accepted: 05/09/2013] [Indexed: 01/22/2023]
Abstract
Primary effusion lymphoma (PEL) is an aggressive form of non-Hodgkin's B-cell lymphoma associated with infection by Kaposi's sarcoma-associated herpes virus (KSHV). (+)-JQ1 and I-BET151 are two recently described novel small-molecule inhibitors of BET bromodomain chromatin-associated proteins that have shown impressive preclinical activity in cancers in which MYC is overexpressed at the transcriptional level due to chromosomal translocations that bring the MYC gene under the control of a super-enhancer. PEL cells, in contrast, lack structural alterations in the MYC gene, but have deregulated Myc protein due to the activity of KSHV-encoded latent proteins. We report that PEL cell lines are highly sensitive to bromodomain and extra-terminal (BET) bromodomain inhibitors-induced growth inhibition and undergo G0/G1 cell-cycle arrest, apoptosis and cellular senescence, but without the induction of lytic reactivation, upon treatment with these drugs. Treatment of PEL cell lines with BET inhibitors suppressed the expression of MYC and resulted in a genome-wide perturbation of MYC-dependent genes. Silencing of BRD4 and MYC expression blocked cell proliferation and cell-cycle progression, while ectopic expression of MYC from a retroviral promoter rescued cells from (+)-JQ1-induced growth arrest. In a xenograft model of PEL, (+)-JQ1 significantly reduced tumor growth and improved survival. Taken collectively, our results demonstrate that the utility of BET inhibitors may not be limited to cancers in which genomic alterations result in extremely high expression of MYC and they may have equal or perhaps greater activity against cancers in which the MYC genomic locus is structurally intact and c-Myc protein is deregulated at the post-translational level and is only modestly overexpressed.
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MESH Headings
- Animals
- Antineoplastic Agents/pharmacology
- Apoptosis/drug effects
- Azepines/pharmacology
- Cell Cycle Checkpoints/drug effects
- Cell Cycle Proteins
- Cell Line, Tumor
- Cell Nucleus/metabolism
- Cell Proliferation/drug effects
- Cell Survival/drug effects
- Cell Survival/genetics
- Cellular Senescence/drug effects
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Female
- Gene Expression Regulation, Neoplastic/genetics
- Herpesvirus 8, Human
- Heterocyclic Compounds, 4 or More Rings/pharmacology
- Humans
- Inhibitory Concentration 50
- Lymphoma, Primary Effusion/genetics
- Lymphoma, Primary Effusion/metabolism
- Lymphoma, Primary Effusion/pathology
- Lymphoma, Primary Effusion/virology
- Nuclear Proteins/antagonists & inhibitors
- Protein Binding/drug effects
- Protein Transport
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- Transcription Factors/antagonists & inhibitors
- Transcription, Genetic
- Triazoles/pharmacology
- Tumor Burden/drug effects
- Virus Replication/drug effects
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Bhairavi Tolani
- Jane Anne Nohl Division of Hematology and Center for the Study of Blood Diseases, University of Southern California Keck School of Medicine, Los Angeles, California, United States of America
| | - Ramakrishnan Gopalakrishnan
- Jane Anne Nohl Division of Hematology and Center for the Study of Blood Diseases, University of Southern California Keck School of Medicine, Los Angeles, California, United States of America
| | - Vasu Punj
- Jane Anne Nohl Division of Hematology and Center for the Study of Blood Diseases, University of Southern California Keck School of Medicine, Los Angeles, California, United States of America
| | - Hittu Matta
- Jane Anne Nohl Division of Hematology and Center for the Study of Blood Diseases, University of Southern California Keck School of Medicine, Los Angeles, California, United States of America
| | - Preet M. Chaudhary
- Jane Anne Nohl Division of Hematology and Center for the Study of Blood Diseases, University of Southern California Keck School of Medicine, Los Angeles, California, United States of America
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Site-specific association with host and viral chromatin by Kaposi's sarcoma-associated herpesvirus LANA and its reversal during lytic reactivation. J Virol 2014; 88:6762-77. [PMID: 24696474 DOI: 10.1128/jvi.00268-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Latency-associated nuclear antigen (LANA), a multifunctional protein expressed by the Kaposi sarcoma-associated herpesvirus (KSHV) in latently infected cells, is required for stable maintenance of the viral episome. This is mediated by two interactions: LANA binds to specific sequences (LBS1 and LBS2) on viral DNA and also engages host histones, tethering the viral genome to host chromosomes in mitosis. LANA has also been suggested to affect host gene expression, but both the mechanism(s) and role of this dysregulation in KSHV biology remain unclear. Here, we have examined LANA interactions with host chromatin on a genome-wide scale using chromatin immunoprecipitation with high-throughput sequencing (ChIP-seq) and show that LANA predominantly targets human genes near their transcriptional start sites (TSSs). These host LANA-binding sites are generally found within transcriptionally active promoters and display striking overrepresentation of a consensus DNA sequence virtually identical to the LANA-binding site 1 (LBS1) motif in KSHV DNA. Comparison of the ChIP-seq profile with whole-transcriptome (high-throughput sequencing of RNA transcripts [RNA-seq]) data reveals that few of the genes that are differentially regulated in latent infection are occupied by LANA at their promoters. This suggests that direct LANA binding to promoters is not the prime determinant of altered host transcription in KSHV-infected cells. Most surprisingly, the association of LANA to both host and viral DNA is strongly disrupted during the lytic cycle of KSHV. This disruption can be prevented by the inhibition of viral DNA synthesis, suggesting the existence of novel and potent regulatory mechanisms linked to either viral DNA replication or late gene expression. IMPORTANCE Here, we employ complementary genome-wide analyses to evaluate the distribution of the highly abundant latency-associated nuclear antigen, LANA, on the host genome and its impact on host gene expression during KSHV latent infection. Combined, ChIP-seq and RNA-seq reveal that LANA accumulates at active gene promoters that harbor specific short DNA sequences that are highly reminiscent of its cognate binding sites in the virus genome. Unexpectedly, we found that such association does not lead to remodeling of global host transcription during latency. We also report for the first time that LANA's ability to bind host and viral chromatin is highly dynamic and is disrupted in cells undergoing an extensive lytic reactivation. This therefore suggests that the association of LANA to chromatin during a productive infection cycle is controlled by a new regulatory mechanism.
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Beauchemin C, Moerke NJ, Faloon P, Kaye KM. Assay Development and High-Throughput Screening for Inhibitors of Kaposi's Sarcoma-Associated Herpesvirus N-Terminal Latency-Associated Nuclear Antigen Binding to Nucleosomes. ACTA ACUST UNITED AC 2014; 19:947-58. [PMID: 24518064 DOI: 10.1177/1087057114520973] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 01/03/2014] [Indexed: 11/17/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) has a causative role in several human malignancies, especially in immunocompromised hosts. KSHV latently infects tumor cells and persists as an extrachromosomal episome (plasmid). KSHV latency-associated nuclear antigen (LANA) mediates KSHV episome persistence. LANA binds specific KSHV sequence to replicate viral DNA. In addition, LANA tethers KSHV genomes to mitotic chromosomes to efficiently segregate episomes to daughter nuclei after mitosis. N-terminal LANA (N-LANA) binds histones H2A and H2B to attach to chromosomes. Currently, there are no specific inhibitors of KSHV latent infection. To enable high-throughput screening (HTS) of inhibitors of N-LANA binding to nucleosomes, here we develop, miniaturize, and validate a fluorescence polarization (FP) assay that detects fluorophore-labeled N-LANA peptide binding to nucleosomes. We also miniaturize a counterscreen to identify DNA intercalators that nonspecifically inhibit N-LANA binding to nucleosomes, and also develop an enzyme-linked immunosorbent assay to assess N-LANA binding to nucleosomes in the absence of fluorescence. HTS of libraries containing more than 350,000 compounds identified multiple compounds that inhibited N-LANA binding to nucleosomes. No compounds survived all counterscreens, however. More complex small-molecule libraries will likely be necessary to identify specific inhibitors of N-LANA binding to histones H2A and H2B; these assays should prove useful for future screens.
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Affiliation(s)
- Chantal Beauchemin
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Nathan J Moerke
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Patrick Faloon
- Broad Institute, Center for the Science of Therapeutics, Therapeutics Platform, Cambridge, USA
| | - Kenneth M Kaye
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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De León Vázquez E, Juillard F, Rosner B, Kaye KM. A short sequence immediately upstream of the internal repeat elements is critical for KSHV LANA mediated DNA replication and impacts episome persistence. Virology 2013; 448:344-55. [PMID: 24314665 DOI: 10.1016/j.virol.2013.10.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 08/12/2013] [Accepted: 10/18/2013] [Indexed: 02/06/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus LANA (1162 residues) mediates episomal persistence of viral genomes during latency. LANA mediates viral DNA replication and segregates episomes to daughter nuclei. A 59 residue deletion immediately upstream of the internal repeat elements rendered LANA highly deficient for DNA replication and modestly deficient for the ability to segregate episomes, while smaller deletions did not. The 59 amino acid deletion reduced LANA episome persistence by ~14-fold, while sequentially smaller deletions resulted in ~3-fold, or no deficiency. Three distinct LANA regions reorganized heterochromatin, one of which contains the deleted sequence, but the deletion did not abolish LANA's ability to alter chromatin. Therefore, this work identifies a short internal LANA sequence that is critical for DNA replication, has modest effects on episome segregation, and substantially impacts episome persistence; this region may exert its effects through an interacting host cell protein(s).
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Affiliation(s)
- Erika De León Vázquez
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, United States
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42
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Analysis of Kaposi's sarcoma-associated herpesvirus latent replication using a real-time polymerase chain reaction technique. J Virol Methods 2013; 193:660-6. [DOI: 10.1016/j.jviromet.2013.07.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 07/29/2013] [Accepted: 07/31/2013] [Indexed: 11/19/2022]
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43
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Correia B, Cerqueira SA, Beauchemin C, Pires de Miranda M, Li S, Ponnusamy R, Rodrigues L, Schneider TR, Carrondo MA, Kaye KM, Simas JP, McVey CE. Crystal structure of the gamma-2 herpesvirus LANA DNA binding domain identifies charged surface residues which impact viral latency. PLoS Pathog 2013; 9:e1003673. [PMID: 24146618 PMCID: PMC3798461 DOI: 10.1371/journal.ppat.1003673] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/16/2013] [Indexed: 01/12/2023] Open
Abstract
Latency-associated nuclear antigen (LANA) mediates γ2-herpesvirus genome persistence and regulates transcription. We describe the crystal structure of the murine gammaherpesvirus-68 LANA C-terminal domain at 2.2 Å resolution. The structure reveals an alpha-beta fold that assembles as a dimer, reminiscent of Epstein-Barr virus EBNA1. A predicted DNA binding surface is present and opposite this interface is a positive electrostatic patch. Targeted DNA recognition substitutions eliminated DNA binding, while certain charged patch mutations reduced bromodomain protein, BRD4, binding. Virus containing LANA abolished for DNA binding was incapable of viable latent infection in mice. Virus with mutations at the charged patch periphery exhibited substantial deficiency in expansion of latent infection, while central region substitutions had little effect. This deficiency was independent of BRD4. These results elucidate the LANA DNA binding domain structure and reveal a unique charged region that exerts a critical role in viral latent infection, likely acting through a host cell protein(s). Herpesviruses establish life-long latent infections. During latency, gammaherpesviruses, such as Kaposi's sarcoma-associated herpesvirus (KSHV), persist as multicopy, circularized genomes in the cell nucleus and express a small subset of viral genes. KSHV latency-associated nuclear antigen (LANA) is the predominant gene expressed during latent infection. C-terminal LANA binds KSHV terminal repeat (TR) DNA to mediate DNA replication. TR DNA binding also allows tethering of the viral genome to mitotic chromosomes to mediate DNA segregation to daughter nuclei. We describe here the crystal structure of the murine gammaherpesvirus 68 LANA DNA binding domain, which is homologous to that of KSHV LANA. The structure revealed a dimer and we identified residues involved in the interaction with viral DNA. Mutation of these residues abolished DNA binding and viable latency establishment in a mouse model of infection. We also identified a positively charged patch on the dimer surface opposite to the DNA binding region and found this patch exerts an important role in the virus's ability to expand latent infection in vivo. This work elucidates the structure of the LANA DNA binding domain and identifies a novel surface feature that is critical for viral latent infection, likely by acting through a host cell protein.
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Affiliation(s)
- Bruno Correia
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Sofia A. Cerqueira
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Chantal Beauchemin
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marta Pires de Miranda
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Shijun Li
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Rajesh Ponnusamy
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lénia Rodrigues
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | | | - Maria A. Carrondo
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| | - Kenneth M. Kaye
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| | - J. Pedro Simas
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| | - Colin E. McVey
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail: (MAC); (KMK); (JPS); (CEM)
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44
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Domsic JF, Chen HS, Lu F, Marmorstein R, Lieberman PM. Molecular basis for oligomeric-DNA binding and episome maintenance by KSHV LANA. PLoS Pathog 2013; 9:e1003672. [PMID: 24146617 PMCID: PMC3798644 DOI: 10.1371/journal.ppat.1003672] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 08/16/2013] [Indexed: 12/20/2022] Open
Abstract
LANA is the KSHV-encoded terminal repeat binding protein essential for viral replication and episome maintenance during latency. We have determined the X-ray crystal structure of LANA C-terminal DNA binding domain (LANADBD) to reveal its capacity to form a decameric ring with an exterior DNA binding surface. The dimeric core is structurally similar to EBV EBNA1 with an N-terminal arm that regulates DNA binding and is required for replication function. The oligomeric interface between LANA dimers is dispensable for single site DNA binding, but is required for cooperative DNA binding, replication function, and episome maintenance. We also identify a basic patch opposite of the DNA binding surface that is responsible for the interaction with BRD proteins and contributes to episome maintenance function. The structural features of LANADBD suggest a novel mechanism of episome maintenance through DNA-binding induced oligomeric assembly. Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latent infections that are associated with several cancers including Kaposi's sarcoma, pleural effusion lymphoma, and multicentric Caslteman's disease. One of the major viral proteins required for establishment and maintenance of the latent state is the latency-associated nuclear antigen (LANA). LANA binds to DNA sequences within the terminal repeats (TR) of the viral genome and stimulates both DNA replication and episome maintenance during latency. Here we present the X-ray crystal structure of the DNA binding domain of LANA (LANADBD) and show that it has the capacity to form oligomeric complexes upon DNA binding. We characterize structural features of LANADBD that are required for oligomerization, DNA binding, and interaction with host cell BET proteins, BRD2 and BRD4, which are important for mediating multiple functions of LANA, including episome maintenance.
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MESH Headings
- Antigens, Viral/chemistry
- Antigens, Viral/genetics
- Antigens, Viral/metabolism
- Cell Line, Tumor
- DNA Replication
- DNA, Viral/chemistry
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Herpesvirus 8, Human/chemistry
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/metabolism
- Humans
- Nuclear Proteins/chemistry
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Plasmids/chemistry
- Plasmids/genetics
- Plasmids/metabolism
- Protein Binding
- Protein Multimerization
- Protein Structure, Quaternary
- Protein Structure, Tertiary
- Structure-Activity Relationship
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Affiliation(s)
- John F. Domsic
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Horng-Shen Chen
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Fang Lu
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Ronen Marmorstein
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RM); (PML)
| | - Paul M. Lieberman
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RM); (PML)
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45
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A structural basis for BRD2/4-mediated host chromatin interaction and oligomer assembly of Kaposi sarcoma-associated herpesvirus and murine gammaherpesvirus LANA proteins. PLoS Pathog 2013; 9:e1003640. [PMID: 24146614 PMCID: PMC3798688 DOI: 10.1371/journal.ppat.1003640] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 08/03/2013] [Indexed: 12/31/2022] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) establishes a lifelong latent infection and causes several malignancies in humans. Murine herpesvirus 68 (MHV-68) is a related γ2-herpesvirus frequently used as a model to study the biology of γ-herpesviruses in vivo. The KSHV latency-associated nuclear antigen (kLANA) and the MHV68 mLANA (orf73) protein are required for latent viral replication and persistence. Latent episomal KSHV genomes and kLANA form nuclear microdomains, termed ‘LANA speckles’, which also contain cellular chromatin proteins, including BRD2 and BRD4, members of the BRD/BET family of chromatin modulators. We solved the X-ray crystal structure of the C-terminal DNA binding domains (CTD) of kLANA and MHV-68 mLANA. While these structures share the overall fold with the EBNA1 protein of Epstein-Barr virus, they differ substantially in their surface characteristics. Opposite to the DNA binding site, both kLANA and mLANA CTD contain a characteristic lysine-rich positively charged surface patch, which appears to be a unique feature of γ2-herpesviral LANA proteins. Importantly, kLANA and mLANA CTD dimers undergo higher order oligomerization. Using NMR spectroscopy we identified a specific binding site for the ET domains of BRD2/4 on kLANA. Functional studies employing multiple kLANA mutants indicate that the oligomerization of native kLANA CTD dimers, the characteristic basic patch and the ET binding site on the kLANA surface are required for the formation of kLANA ‘nuclear speckles’ and latent replication. Similarly, the basic patch on mLANA contributes to the establishment of MHV-68 latency in spleen cells in vivo. In summary, our data provide a structural basis for the formation of higher order LANA oligomers, which is required for nuclear speckle formation, latent replication and viral persistence. Kaposi sarcoma-associated herpesvirus (KSHV) causes Kaposi Sarcoma, Primary Effusion lymphoma and the plasma cell variant of Multicentric Castleman's Disease. Its oncogenic effect is linked to its ability to persist in a latent form for the life time of infected individuals. During latency viral genomes are replicated and passed to daughter cells in synchrony with the infected cell without the formation of new virions. A key viral protein in this process is the latency-associated nuclear antigen, LANA. In latently infected cells, viral genomes and LANA form characteristic nuclear microdomains, termed ‘LANA speckles’, which also contain cellular chromatin components. We have solved the crystal structure of the c-terminal, DNA-binding, domain (CTD) of KSHV LANA (kLANA) and its homologue mLANA of a related murine γ2-herpesvirus, which is frequently used as a model to study latent persistence in vivo. We also identified the binding site for two chromatin proteins, BRD2/4, by NMR spectroscopy. We demonstrate the functional importance of these structural features, and their contribution to latent replication and ‘LANA speckle’ formation, in cell culture and in vivo experiments. Our results provide a structural basis for the assembly of LANA-containing nuclear structures that are required for latent viral replication and persistence.
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Identification of Kaposi's sarcoma-associated herpesvirus LANA regions important for episome segregation, replication, and persistence. J Virol 2013; 87:12270-83. [PMID: 24006437 DOI: 10.1128/jvi.01243-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) is a 1,162-amino-acid protein that mediates the maintenance of episomal viral genomes in latently infected cells. The two central components of episome persistence are DNA replication with each cell division and the segregation of DNA to progeny nuclei. LANA self-associates to bind KSHV terminal-repeat (TR) DNA and to mediate its replication. LANA also simultaneously binds to TR DNA and mitotic chromosomes to mediate the segregation of episomes to daughter nuclei. The N-terminal region of LANA binds histones H2A and H2B to attach to mitotic chromosomes, while the C-terminal region binds TR DNA and also associates with chromosomes. Both the N- and C-terminal regions of LANA are essential for episome persistence. We recently showed that deletion of all internal LANA sequences results in highly deficient episome maintenance. Here we assess independent internal LANA regions for effects on episome persistence. We generated a panel of LANA mutants that included deletions in the large internal repeat region and in the unique internal sequence. All mutants contained the essential N- and C-terminal regions, and as expected, all maintained the ability to associate with mitotic chromosomes in a wild-type fashion and to bind TR DNA, as assessed by electrophoretic mobility shift assays (EMSA). Deletion of the internal regions did not reduce the half-life of LANA. Notably, deletions within either the repeat elements or the unique sequence resulted in deficiencies in DNA replication. However, only the unique internal sequence exerted effects on the ability of LANA to retain green fluorescent protein (GFP) expression from TR-containing episomes deficient in DNA replication, consistent with a role in episome segregation; this region did not independently associate with mitotic chromosomes. All mutants were deficient in episome persistence, and the deficiencies ranged from minor to severe. Mutants deficient in DNA replication that contained deletions within the unique internal sequence had the most-severe deficits. These data suggest that internal LANA regions exert critical roles in LANA-mediated DNA replication, segregation, and episome persistence, likely through interactions with key host cell factors.
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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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H2AX phosphorylation is important for LANA-mediated Kaposi's sarcoma-associated herpesvirus episome persistence. J Virol 2013; 87:5255-69. [PMID: 23449797 DOI: 10.1128/jvi.03575-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The DNA damage response (DDR) of host cells is utilized by a number of viruses to establish and propagate their genomes in the infected cells. We examined the expression of the DDR genes during Kaposi's sarcoma-associated herpesvirus (KSHV) infection of human peripheral blood mononuclear cells (PBMCs). The genes were mostly downregulated, except H2AX, which was upregulated during infection. H2AX is important for gammaherpesvirus infectivity, and its phosphorylation at serine 139 is crucial for maintenance of latency during mouse gamma-herpesvirus 68 (MHV-68) infection. We now also observed phosphorylation of H2AX at serine 139 during KSHV infection. H2AX is a histone H2A isoform shown to interact with the latency-associated nuclear antigen (LANA) encoded by KSHV. Here, we show that LANA directly interacted with H2AX through domains at both its N and C termini. The phosphorylated form of H2AX (γH2AX) was shown to colocalize with LANA. Chromatin immunoprecipitation (ChIP) assays showed that a reduction in H2AX levels resulted in reduced binding of LANA with KSHV terminal repeats (TRs). Binding preferences of H2AX and γH2AX along the KSHV episome were examined by whole-episome ChIP analysis. We showed that γH2AX had a higher relative binding activity along the TR regions than that of the long unique region (LUR), which highlighted the importance of H2AX phosphorylation during KSHV infection. Furthermore, knockdown of H2AX resulted in decreased KSHV episome copy number. Notably, the C terminus of LANA contributed to phosphorylation of H2AX. However, phosphorylation was not dependent on the ability of LANA to drive KSHV-infected cells into S-phase. Thus, H2AX contributes to association of LANA with the TRs, and phosphorylation of H2AX is likely important for its increased density at the TRs.
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Timeless-dependent DNA replication-coupled recombination promotes Kaposi's Sarcoma-associated herpesvirus episome maintenance and terminal repeat stability. J Virol 2013; 87:3699-709. [PMID: 23325691 DOI: 10.1128/jvi.02211-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kaposi's Sarcoma-associated herpesvirus (KSHV) is maintained as a stable episome in latently infected pleural effusion lymphoma (PEL) cells. Episome maintenance is conferred by the binding of the KSHV-encoded LANA protein to the viral terminal repeats (TR). Here, we show that DNA replication in the KSHV TR is coupled with DNA recombination and mediated in part through the cellular replication fork protection factors Timeless (Tim) and Tipin. We show by two-dimensional (2D) agarose gel electrophoresis that replication forks naturally stall and form recombination-like structures at the TR during an unperturbed cell cycle. Chromatin immunoprecipitation (ChIP) assays revealed that Tim and Tipin are selectively enriched at the KSHV TR during S phase and in a LANA-dependent manner. Tim depletion inhibited LANA-dependent TR DNA replication and caused the loss of KSHV episomes from latently infected PEL cells. Tim depletion resulted in the aberrant accumulation of recombination structures and arrested MCM helicase at TR. Tim depletion did not induce the KSHV lytic cycle or apoptotic cell death. We propose that KSHV episome maintenance requires Tim-assisted replication fork protection at the viral terminal repeats and that Tim-dependent recombination-like structures form at TR to promote DNA repeat stability and viral genome maintenance.
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