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Prabhakar AT, Morgan IM. A new role for human papillomavirus 16 E2: Mitotic activation of the DNA damage response to promote viral genome segregation. Tumour Virus Res 2024; 18:200291. [PMID: 39245413 PMCID: PMC11416546 DOI: 10.1016/j.tvr.2024.200291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 09/03/2024] [Accepted: 09/05/2024] [Indexed: 09/10/2024] Open
Abstract
Human papillomaviruses (HPV) are causative agents in around 5% of all human cancers. To identify and develop new targeted HPV therapeutics we must enhance our understanding of the viral life cycle and how it interacts with the host. The HPV E2 protein dimerizes and binds to 12bp target sequences in the viral genome and segregates the viral genome during mitosis. In this function, E2 binds to the viral genome and the host chromatin simultaneously, ensuring viral genomes reside in daughter nuclei following cell division. We have demonstrated that a mitotic interaction between E2 and the DNA damage response (DDR) protein TOPBP1 is required for E2 segregation function. In non-infected cells, following DNA damage, TOPBP1 is recruited to the mitotic host genome via interaction with MDC1 and this interaction protects DNA integrity during mitosis. Recently we demonstrated that the E2-TOPBP1 interaction activates the DNA damage response (DDR) during mitosis independently from external stimuli, promoting TOPBP1 interaction with mitotic chromatin and therefore segregation of the viral genome. Therefore, the virus has hijacked an existing host mechanism in order to segregate the viral genome. This intricate E2 function will be described and discussed.
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Affiliation(s)
- Apurva T Prabhakar
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, VA, 23298, USA.
| | - Iain M Morgan
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, VA, 23298, USA; VCU Massey Cancer Center, Richmond, VA, 23298, USA.
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Prabhakar AT, James CD, Fontan CT, Otoa R, Wang X, Bristol ML, Yeager C, Hill RD, Dubey A, Wu SY, Chiang CM, Morgan IM. Direct interaction with the BRD4 carboxyl-terminal motif (CTM) and TopBP1 is required for human papillomavirus 16 E2 association with mitotic chromatin and plasmid segregation function. J Virol 2023; 97:e0078223. [PMID: 37712702 PMCID: PMC10617519 DOI: 10.1128/jvi.00782-23] [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: 05/24/2023] [Accepted: 07/25/2023] [Indexed: 09/16/2023] Open
Abstract
IMPORTANCE Human papillomavirus 16 (HPV16) is a causative agent in around 3%-4% of all human cancers, and currently, there are no anti-viral therapeutics available for combating this disease burden. In order to identify new therapeutic targets, we must increase our understanding of the HPV16 life cycle. Previously, we demonstrated that an interaction between E2 and the cellular protein TopBP1 mediates the plasmid segregation function of E2, allowing distribution of viral genomes into daughter nuclei following cell division. Here, we demonstrate that E2 interaction with an additional host protein, BRD4, is also essential for E2 segregation function, and that BRD4 exists in a complex with TopBP1. Overall, these results enhance our understanding of a critical part of the HPV16 life cycle and presents several therapeutic targets for disruption of the viral life cycle.
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Affiliation(s)
- Apurva T. Prabhakar
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Claire D. James
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Christian T. Fontan
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Raymonde Otoa
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Xu Wang
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Molly L. Bristol
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
- VCU Massey Cancer Center, Richmond, Virginia, USA
| | - Calvin Yeager
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Ronald D. Hill
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Aanchal Dubey
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Shwu-Yuan Wu
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Cheng-Ming Chiang
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Iain M. Morgan
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
- VCU Massey Cancer Center, Richmond, Virginia, USA
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Prabhakar AT, James CD, Fontan CT, Otoa R, Wang X, Bristol ML, Hill RD, Dubey A, Wu SY, Chiang CM, Morgan IM. Direct interaction with the BRD4 carboxyl-terminal motif (CTM) and TopBP1 is required for human papillomavirus 16 E2 association with mitotic chromatin and plasmid segregation function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542291. [PMID: 37292798 PMCID: PMC10245903 DOI: 10.1101/2023.05.25.542291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
During the human papillomavirus 16 life cycle, the E2 protein binds simultaneously to the viral genome and host chromatin throughout mitosis, ensuring viral genomes reside in daughter cell nuclei following cell division. Previously, we demonstrated that CK2 phosphorylation of E2 on serine 23 promotes interaction with TopBP1, and that this interaction is required for optimum E2 mitotic chromatin association and plasmid segregation function. Others have implicated BRD4 in mediating the plasmid segregation function of E2 and we have demonstrated that there is a TopBP1-BRD4 complex in the cell. We therefore further investigated the role of the E2-BRD4 interaction in mediating E2 association with mitotic chromatin and plasmid segregation function. Using a combination of immunofluorescence and our novel plasmid segregation assay in U2OS and N/Tert-1 cells stably expressing a variety of E2 mutants, we report that direct interaction with the BRD4 carboxyl-terminal motif (CTM) and TopBP1 is required for E2 association with mitotic chromatin and plasmid segregation. We also identify a novel TopBP1 mediated interaction between E2 and the BRD4 extra-terminal (ET) domain in vivo . Overall, the results demonstrate that direct interaction with TopBP1 and the BRD4 CTM are required for E2 mitotic chromatin association and plasmid segregation function. Disruption of this complex offers therapeutic options for targeting segregation of viral genomes into daughter cells, potentially combatting HPV16 infections, and cancers that retain episomal genomes. Importance HPV16 is a causative agent in around 3-4% of all human cancers and currently there are no anti-viral therapeutics available for combating this disease burden. In order to identify new therapeutic targets, we must increase our understanding of the HPV16 life cycle. Previously, we demonstrated that an interaction between E2 and the cellular protein TopBP1 mediates the plasmid segregation function of E2, allowing distribution of viral genomes into daughter nuclei following cell division. Here, we demonstrate that E2 interaction with an additional host protein, BRD4, is also essential for E2 segregation function, and that BRD4 exists in a complex with TopBP1. Overall, these results enhance our understanding of a critical part of the HPV16 life cycle and presents several therapeutic targets for disruption of the viral life cycle.
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Interaction with TopBP1 Is Required for Human Papillomavirus 16 E2 Plasmid Segregation/Retention Function during Mitosis. J Virol 2022; 96:e0083022. [PMID: 35880889 PMCID: PMC9400484 DOI: 10.1128/jvi.00830-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human papillomavirus 16 (HPV16) E2 is a DNA-binding protein that regulates transcription, replication and potentially, segregation of the HPV16 genome during the viral life cycle. In the segregation model, E2 simultaneously binds to viral and host chromatin, acting as a bridge to ensure that viral genomes reside in daughter nuclei following cell division. The host chromatin receptor for E2 mediating this function is unknown. Recently, we demonstrated that CK2 phosphorylation of E2 on serine 23 (S23) is required for interaction with TopBP1, and that this interaction promotes E2 and TopBP1 recruitment to mitotic chromatin. Here, we demonstrate that in U2OS cells expressing wild-type E2 and a non-TopBP1-binding mutant (S23A, serine 23 mutated to alanine), interaction with TopBP1 is essential for E2 recruitment of plasmids to mitotic chromatin. Using novel quantitative segregation assays, we demonstrate that interaction with TopBP1 is required for E2 plasmid segregation function in U2OS and N/Tert-1 cells. Small interfering RNA (siRNA) knockdown of TopBP1 or CK2 enzyme components disrupts E2 segregation/retention function. The interaction of E2 with TopBP1 promotes increased levels of E2 protein during mitosis in U2OS and N/Tert-1 cells, as well as in human foreskin keratinocytes (HFK) immortalized by the HPV16 genome. Overall, our results demonstrate that E2 has plasmid segregation activity, and that the E2-TopBP1 interaction is essential for this E2 function. IMPORTANCE HPV16 causes 3% to 4% of all human cancers. It is proposed that during the viral life cycle, the viral genome is actively segregated into daughter nuclei, ensuring viral replication in the subsequent S phase. The E2 protein potentially bridges the viral and host genomes during mitosis to mediate segregation of the circular viral plasmid. Here, we demonstrate that E2 has the ability to mediate plasmid segregation, and that this function is dependent upon interaction with the host protein TopBP1. Additionally, we demonstrate that the E2-TopBP1 interaction promotes enhanced E2 expression during mitosis, which likely promotes the plasmid segregation function of E2. Overall, our results present a mechanism of how HPV16 can segregate its viral genome during an active infection, a critical aspect of the viral life cycle.
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Prabhakar AT, James CD, Das D, Otoa R, Day M, Burgner J, Fontan CT, Wang X, Glass SH, Wieland A, Donaldson MM, Bristol ML, Li R, Oliver AW, Pearl LH, Smith BO, Morgan IM. CK2 Phosphorylation of Human Papillomavirus 16 E2 on Serine 23 Promotes Interaction with TopBP1 and Is Critical for E2 Interaction with Mitotic Chromatin and the Viral Life Cycle. mBio 2021; 12:e0116321. [PMID: 34544280 PMCID: PMC8546539 DOI: 10.1128/mbio.01163-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 08/19/2021] [Indexed: 01/05/2023] Open
Abstract
During the human papillomavirus 16 (HPV16) life cycle, the E2 protein interacts with host factors to regulate viral transcription, replication, and genome segregation/retention. Our understanding of host partner proteins and their roles in E2 functions remains incomplete. Here we demonstrate that CK2 phosphorylation of E2 on serine 23 promotes interaction with TopBP1 in vitro and in vivo and that E2 is phosphorylated on this residue during the HPV16 life cycle. We investigated the consequences of mutating serine 23 on E2 functions. E2-S23A (E2 with serine 23 mutated to alanine) activates and represses transcription identically to E2-WT (wild-type E2), and E2-S23A is as efficient as E2-WT in transient replication assays. However, E2-S23A has compromised interaction with mitotic chromatin compared with E2-WT. In E2-WT cells, both E2 and TopBP1 levels increase during mitosis compared with vector control cells. In E2-S23A cells, neither E2 nor TopBP1 levels increase during mitosis. Introduction of the S23A mutation into the HPV16 genome resulted in delayed immortalization of human foreskin keratinocytes (HFK) and higher episomal viral genome copy number in resulting established HFK. Remarkably, S23A cells had a disrupted viral life cycle in organotypic raft cultures, with a loss of E2 expression and a failure of viral replication. Overall, our results demonstrate that CK2 phosphorylation of E2 on serine 23 promotes interaction with TopBP1 and that this interaction is critical for the viral life cycle. IMPORTANCE Human papillomaviruses are causative agents in around 5% of all cancers, with no specific antiviral therapeutics available for treating infections or resultant cancers. In this report, we demonstrate that phosphorylation of HPV16 E2 by CK2 promotes formation of a complex with the cellular protein TopBP1 in vitro and in vivo. This complex results in stabilization of E2 during mitosis. We demonstrate that CK2 phosphorylates E2 on serine 23 in vivo and that CK2 inhibitors disrupt the E2-TopBP1 complex. Mutation of E2 serine 23 to alanine disrupts the HPV16 life cycle, hindering immortalization and disrupting the viral life cycle, demonstrating a critical function for this residue.
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Affiliation(s)
- Apurva T. Prabhakar
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Claire D. James
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Dipon Das
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Raymonde Otoa
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Matthew Day
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - John Burgner
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Christian T. Fontan
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Xu Wang
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Sarah H. Glass
- VCU School of Dentistry, Department of Oral Diagnostic Sciences, Richmond, Virginia, USA
| | - Andreas Wieland
- Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Mary M. Donaldson
- School of Veterinary Medicine, University of Glasgow, Bearsden, United Kingdom
| | - Molly L. Bristol
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
| | - Renfeng Li
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
- VCU Massey Cancer Center, Richmond, Virginia, USA
| | - Anthony W. Oliver
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Laurence H. Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Brian O. Smith
- Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Iain M. Morgan
- Virginia Commonwealth University (VCU), Philips Institute for Oral Health Research, School of Dentistry, Richmond, Virginia, USA
- VCU Massey Cancer Center, Richmond, Virginia, USA
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Masumoto J, Zhou W, Morikawa S, Hosokawa S, Taguchi H, Yamamoto T, Kurata M, Kaneko N. Molecular biology of autoinflammatory diseases. Inflamm Regen 2021; 41:33. [PMID: 34635190 PMCID: PMC8507398 DOI: 10.1186/s41232-021-00181-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 09/09/2021] [Indexed: 12/25/2022] Open
Abstract
The long battle between humans and various physical, chemical, and biological insults that cause cell injury (e.g., products of tissue damage, metabolites, and/or infections) have led to the evolution of various adaptive responses. These responses are triggered by recognition of damage-associated molecular patterns (DAMPs) and/or pathogen-associated molecular patterns (PAMPs), usually by cells of the innate immune system. DAMPs and PAMPs are recognized by pattern recognition receptors (PRRs) expressed by innate immune cells; this recognition triggers inflammation. Autoinflammatory diseases are strongly associated with dysregulation of PRR interactomes, which include inflammasomes, NF-κB-activating signalosomes, type I interferon-inducing signalosomes, and immuno-proteasome; disruptions of regulation of these interactomes leads to inflammasomopathies, relopathies, interferonopathies, and proteasome-associated autoinflammatory syndromes, respectively. In this review, we discuss the currently accepted molecular mechanisms underlying several autoinflammatory diseases.
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Affiliation(s)
- Junya Masumoto
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan.
| | - Wei Zhou
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
| | - Shinnosuke Morikawa
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
| | - Sho Hosokawa
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
| | - Haruka Taguchi
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
| | - Toshihiro Yamamoto
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
| | - Mie Kurata
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
| | - Naoe Kaneko
- Department of Pathology, Ehime University Graduate School of Medicine and Proteo-Science Center, Shitsukawa 454, Toon, Ehime, 791-0295, Japan
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Das D, Bristol ML, Pichierri P, Morgan IM. Using a Human Papillomavirus Model to Study DNA Replication and Repair of Wild Type and Damaged DNA Templates in Mammalian Cells. Int J Mol Sci 2020; 21:E7564. [PMID: 33066318 PMCID: PMC7589113 DOI: 10.3390/ijms21207564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/06/2020] [Accepted: 10/12/2020] [Indexed: 12/13/2022] Open
Abstract
Human papillomaviruses have 8kbp DNA episomal genomes that replicate autonomously from host DNA. During initial infection, the virus increases its copy number to 20-50 copies per cell, causing torsional stress on the replicating DNA. This activates the DNA damage response (DDR) and HPV replicates its genome, at least in part, using homologous recombination. An active DDR is on throughout the HPV life cycle. Two viral proteins are required for replication of the viral genome; E2 binds to 12bp palindromic sequences around the A/T rich origin of replication and recruits the viral helicase E1 via a protein-protein interaction. E1 forms a di-hexameric complex that replicates the viral genome in association with host factors. Transient replication assays following transfection with E1-E2 expression plasmids, along with an origin containing plasmid, allow monitoring of E1-E2 replication activity. Incorporating a bacterial lacZ gene into the origin plasmid allows for the determination of replication fidelity. Here we describe how we exploited this system to investigate replication and repair in mammalian cells, including using damaged DNA templates. We propose that this system has the potential to enhance the understanding of cellular components involved in DNA replication and repair.
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Affiliation(s)
- Dipon Das
- Department of Oral and Craniofacial Molecular Biology, VCU Philips Institute for Oral Health Research, Virginia Commonwealth University School of Dentistry, Richmond, VA 23298, USA; (D.D.); (M.L.B.)
| | - Molly L. Bristol
- Department of Oral and Craniofacial Molecular Biology, VCU Philips Institute for Oral Health Research, Virginia Commonwealth University School of Dentistry, Richmond, VA 23298, USA; (D.D.); (M.L.B.)
| | - Pietro Pichierri
- Department of Environment and Health, Istituto Superiore di Sanita’, 00161 Rome, Italy;
| | - Iain M. Morgan
- Department of Oral and Craniofacial Molecular Biology, VCU Philips Institute for Oral Health Research, Virginia Commonwealth University School of Dentistry, Richmond, VA 23298, USA; (D.D.); (M.L.B.)
- VCU Massey Cancer Center, Richmond, VA 23298, USA
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Aydin I, Schelhaas M. Viral Genome Tethering to Host Cell Chromatin: Cause and Consequences. Traffic 2016; 17:327-40. [PMID: 26787361 DOI: 10.1111/tra.12378] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/14/2016] [Accepted: 01/14/2016] [Indexed: 12/26/2022]
Abstract
Viruses are small infectious agents that replicate in cells of a host organism and that evolved to use cellular machineries for all stages of the viral life cycle. Here, we critically assess current knowledge on a particular mechanism of persisting viruses, namely, how they tether their genomes to host chromatin, and what consequences arise from this process. A group of persisting DNA viruses, i.e. gamma-herpesviruses and papillomaviruses (PV), uses this tethering strategy to maintain their genomes in the nuclei during cell division. Thus, these viruses face the challenge of viral genome loss during mitosis, as they are transported with the host chromosomes to the nascent daughter nuclei. Incidentally, another group of viruses, certain retroviruses and PV, have adopted this tethering strategy to deliver their genomes into the nuclei of dividing cells during cell entry. By exploiting a phase in the cell cycle when the nuclear envelope is disassembled, viruses bypass the need to engage with the nuclear import machinery. Recent reports suggest that tethering may induce severe cellular consequences that involve activation of mitotic checkpoints, causing missegregation of host chromosomes and genomic instability, which may contribute to cancer.
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Affiliation(s)
- Inci Aydin
- Cell Biology of Virus Infection Unit, Institutes of Molecular Virology and Medical Biochemistry, ZMBE, University of Münster, Münster, Germany.,Cells in Motion, CiM, Cluster of Excellence EXC 1003, Münster, Germany
| | - Mario Schelhaas
- Cell Biology of Virus Infection Unit, Institutes of Molecular Virology and Medical Biochemistry, ZMBE, University of Münster, Münster, Germany.,Cells in Motion, CiM, Cluster of Excellence EXC 1003, Münster, Germany
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Verbruggen B, Bickley LK, van Aerle R, Bateman KS, Stentiford GD, Santos EM, Tyler CR. Molecular Mechanisms of White Spot Syndrome Virus Infection and Perspectives on Treatments. Viruses 2016; 8:E23. [PMID: 26797629 PMCID: PMC4728583 DOI: 10.3390/v8010023] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 12/18/2015] [Accepted: 01/06/2016] [Indexed: 02/07/2023] Open
Abstract
Since its emergence in the 1990s, White Spot Disease (WSD) has had major economic and societal impact in the crustacean aquaculture sector. Over the years shrimp farming alone has experienced billion dollar losses through WSD. The disease is caused by the White Spot Syndrome Virus (WSSV), a large dsDNA virus and the only member of the Nimaviridae family. Susceptibility to WSSV in a wide range of crustacean hosts makes it a major risk factor in the translocation of live animals and in commodity products. Currently there are no effective treatments for this disease. Understanding the molecular basis of disease processes has contributed significantly to the treatment of many human and animal pathogens, and with a similar aim considerable efforts have been directed towards understanding host-pathogen molecular interactions for WSD. Work on the molecular mechanisms of pathogenesis in aquatic crustaceans has been restricted by a lack of sequenced and annotated genomes for host species. Nevertheless, some of the key host-pathogen interactions have been established: between viral envelope proteins and host cell receptors at initiation of infection, involvement of various immune system pathways in response to WSSV, and the roles of various host and virus miRNAs in mitigation or progression of disease. Despite these advances, many fundamental knowledge gaps remain; for example, the roles of the majority of WSSV proteins are still unknown. In this review we assess current knowledge of how WSSV infects and replicates in its host, and critique strategies for WSD treatment.
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Affiliation(s)
- Bas Verbruggen
- Biosciences, College of Life & Environmental Sciences, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4, UK.
| | - Lisa K Bickley
- Biosciences, College of Life & Environmental Sciences, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4, UK.
| | - Ronny van Aerle
- European Union Reference Laboratory for Crustacean Diseases, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK.
| | - Kelly S Bateman
- European Union Reference Laboratory for Crustacean Diseases, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK.
| | - Grant D Stentiford
- European Union Reference Laboratory for Crustacean Diseases, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK.
| | - Eduarda M Santos
- Biosciences, College of Life & Environmental Sciences, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4, UK.
| | - Charles R Tyler
- Biosciences, College of Life & Environmental Sciences, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4, UK.
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Guo Y, Hu J, Zhu L, Sun J, Xie L, Kong F, Han L, Li F. Physical Status and Variant Analysis of Human Papillomavirus 16 in Women from Shanghai. Gynecol Obstet Invest 2015; 81:61-70. [DOI: 10.1159/000381775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/18/2015] [Indexed: 11/19/2022]
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Wardlaw CP, Carr AM, Oliver AW. TopBP1: A BRCT-scaffold protein functioning in multiple cellular pathways. DNA Repair (Amst) 2014; 22:165-74. [PMID: 25087188 DOI: 10.1016/j.dnarep.2014.06.004] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 11/25/2022]
Abstract
Human TopBP1 contains nine BRCT domains and functions in DNA replication initiation, checkpoint signalling, DNA repair and influences transcriptional control. TopBP1 and its homologues have been the subject of numerous scientific publications since the last comprehensive review in 2005, emerging as a key scaffold protein that links crucial components within these distinct cellular processes. This review focuses on recently published work, with particular emphasis on structural insights into TopBP1 function and the binding partners identified for DNA replication initiation, DNA-dependent checkpoints, DNA repair and transcription. We further summarise what is known about TopBP1 and links to human disease.
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Affiliation(s)
- Christopher P Wardlaw
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK.
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Antony W Oliver
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
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12
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RACK1, a versatile hub in cancer. Oncogene 2014; 34:1890-8. [PMID: 24882575 DOI: 10.1038/onc.2014.127] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 01/15/2023]
Abstract
RACK1 is a highly conserved intracellular adaptor protein with significant homology to Gβ and was originally identified as the anchoring protein for activated protein kinase C. In the past 20 years, the number of binding partners and validated cellular functions for RACK1 has increased, which facilitates clarification of its involvement in different biological events. In this review, we will focus on its role in cancer, summarizing its aberrant expression, pro- or anti-oncogenic effects and the underlying mechanisms in various cancers.
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HPV16 E2-mediated potentiation of NF-κB activation induced by TNF-α involves parallel activation of STAT3 with a reduction in E2-induced apoptosis. Mol Cell Biochem 2014; 394:77-90. [PMID: 24833467 DOI: 10.1007/s11010-014-2083-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 05/03/2014] [Indexed: 02/08/2023]
Abstract
Human papilloma virus is associated with cervical and other tumors, and several cellular conditions also play an important role in carcinogenesis. Human papilloma virus (HPV)-infected cells exhibit activation of NF-κB and STAT3 (mediators of inflammation), but little is known about their regulation by HPV. This study attempts to understand the role of HPV16 E2, an important early protein of HPV16, in the regulation of NF-κB and STAT3 by reporter assays, quantitative reverse transcriptase-polymerase chain reaction, and immunoblotting. We demonstrate that E2 enhances NF-κB activation induced by TNF-α, a proinflammatory cytokine, in both non-tumor- and tumor-derived epithelial cell lines besides potentiating STAT3 transcriptional activity induced by TNF-α in HEK293 cells. E2 increases the expression of RelA and its transcriptional activation, and retention of E2 was observed in the nucleus with significant interaction with RelA (immunoprecipitation) upon TNF-α treatment. Transfection with shRNA-RelA or pretreatment with a STAT3 inhibitor had a negative effect on the ability of E2 to enhance TNF-α-induced NF-κB activation. Experiments with co-expression of a mutant of STAT3 with E2 also suggested that the activation of STAT3 is indispensible for TNF-α-induced NF-κB activation. Inhibition of STAT3 activation enhanced E2-induced apoptosis, whereas parallel activation of NF-κB and STAT3 by the combined action of E2 and TNF-α increased the expression of their common targets, cyclin-D1, c-Myc, survivin, and Bcl-2, leading to a decrease in E2-induced apoptosis (viability and cell cycle). Our results reveal novel mechanisms by which E2 may regulate NF-κB and STAT3 activation in the presence of TNF-α with implications on the survival of HPV-infected cells.
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14
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Muller M, Demeret C. The HPV E2-Host Protein-Protein Interactions: A Complex Hijacking of the Cellular Network. Open Virol J 2012; 6:173-89. [PMID: 23341853 PMCID: PMC3547520 DOI: 10.2174/1874357901206010173] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 07/20/2012] [Accepted: 07/30/2012] [Indexed: 11/22/2022] Open
Abstract
Over 100 genotypes of human papillomaviruses (HPVs) have been identified as being responsible for unapparent infections or for lesions ranging from benign skin or genital warts to cancer. The pathogenesis of HPV results from complex relationships between viral and host factors, driven in particular by the interplay between the host proteome and the early viral proteins. The E2 protein regulates the transcription, the replication as well as the mitotic segregation of the viral genome through the recruitment of host cell factors to the HPV regulatory region. It is thereby a pivotal factor for the productive viral life cycle and for viral persistence, a major risk factor for cancer development. In addition, the E2 proteins have been shown to engage numerous interactions through which they play important roles in modulating the host cell. Such E2 activities are probably contributing to create cell conditions appropriate for the successive stages of the viral life cycle, and some of these activities have been demonstrated only for the oncogenic high-risk HPV. The recent mapping of E2-host protein-protein interactions with 12 genotypes representative of HPV diversity has shed some light on the large complexity of the host cell hijacking and on its diversity according to viral genotypes. This article reviews the functions of E2 as they emerge from the E2/host proteome interplay, taking into account the large-scale comparative interactomic study.
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Affiliation(s)
- Mandy Muller
- Unité de Génétique, Papillomavirus et Cancer Humain (GPCH), Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France ; Univ. Paris Diderot, Sorbonne Paris cite, Cellule Pasteur, rue du Docteur Roux, 75015 Paris, France
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15
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Pang CL, Thierry F. Human papillomavirus proteins as prospective therapeutic targets. Microb Pathog 2012; 58:55-65. [PMID: 23164805 DOI: 10.1016/j.micpath.2012.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 11/07/2012] [Accepted: 11/07/2012] [Indexed: 01/01/2023]
Abstract
Human papillomaviruses (HPV) are the causative agents of a subset of cervical cancers that are associated with persistent viral infection. The HPV genome is an ∼8 kb circle of double-stranded DNA that encodes eight viral proteins, among which the products of the E6 and E7 open reading frames are recognized as being the primary HPV oncogenes. E6 and E7 are expressed in pre-malignant lesions as well as in cervical cancers; hence these proteins have been extensively studied as potential targets for HPV therapies and novel vaccines. Here we review the expression and functions of E6 and E7 in the viral vegetative cycle and in oncogenesis. We also explore the expression and functions of other HPV proteins, including those with oncogenic properties, and discuss the potential of these molecules as alternative therapeutic targets.
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Affiliation(s)
- Chai Ling Pang
- Singapore Immunology Network, 8A Biomedical Grove, #4-06 Immunos, A*STAR, Singapore 138648, Singapore
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16
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An interaction between human papillomavirus 16 E2 and TopBP1 is required for optimum viral DNA replication and episomal genome establishment. J Virol 2012; 86:12806-15. [PMID: 22973044 DOI: 10.1128/jvi.01002-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In human papillomavirus DNA replication, the viral protein E2 forms homodimers and binds to 12-bp palindromic DNA sequences surrounding the origin of DNA replication. Via a protein-protein interaction, it then recruits the viral helicase E1 to an A/T-rich origin of replication, whereupon a dihexamer forms, resulting in DNA replication initiation. In order to carry out DNA replication, the viral proteins must interact with host factors that are currently not all known. An attractive cellular candidate for regulating viral replication is TopBP1, a known interactor of the E2 protein. In mammalian DNA replication, TopBP1 loads DNA polymerases onto the replicative helicase after the G(1)-to-S transition, and this process is tightly cell cycle controlled. The direct interaction between E2 and TopBP1 would allow E2 to bypass this cell cycle control, resulting in DNA replication more than once per cell cycle, which is a requirement for the viral life cycle. We report here the generation of an HPV16 E2 mutant compromised in TopBP1 interaction in vivo and demonstrate that this mutant retains transcriptional activation and repression functions but has suboptimal DNA replication potential. Introduction of this mutant into a viral life cycle model results in the failure to establish viral episomes. The results present a potential new antiviral target, the E2-TopBP1 interaction, and increase our understanding of the viral life cycle, suggesting that the E2-TopBP1 interaction is essential.
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17
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Adams DR, Ron D, Kiely PA. RACK1, A multifaceted scaffolding protein: Structure and function. Cell Commun Signal 2011; 9:22. [PMID: 21978545 PMCID: PMC3195729 DOI: 10.1186/1478-811x-9-22] [Citation(s) in RCA: 333] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Accepted: 10/06/2011] [Indexed: 12/17/2022] Open
Abstract
The Receptor for Activated C Kinase 1 (RACK1) is a member of the tryptophan-aspartate repeat (WD-repeat) family of proteins and shares significant homology to the β subunit of G-proteins (Gβ). RACK1 adopts a seven-bladed β-propeller structure which facilitates protein binding. RACK1 has a significant role to play in shuttling proteins around the cell, anchoring proteins at particular locations and in stabilising protein activity. It interacts with the ribosomal machinery, with several cell surface receptors and with proteins in the nucleus. As a result, RACK1 is a key mediator of various pathways and contributes to numerous aspects of cellular function. Here, we discuss RACK1 gene and structure and its role in specific signaling pathways, and address how posttranslational modifications facilitate subcellular location and translocation of RACK1. This review condenses several recent studies suggesting a role for RACK1 in physiological processes such as development, cell migration, central nervous system (CN) function and circadian rhythm as well as reviewing the role of RACK1 in disease.
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Affiliation(s)
- David R Adams
- Department of Life Sciences, and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
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18
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The use of a human papillomavirus 18 promoter for tissue-specific expression in cervical carcinoma cells. Cell Mol Biol Lett 2011; 16:477-92. [PMID: 21786035 PMCID: PMC6275744 DOI: 10.2478/s11658-011-0018-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 06/29/2011] [Indexed: 11/25/2022] Open
Abstract
The use of tissue-specific promoter elements in the treatment of cervical cancer has been explored in this paper. The P105 promoter of human papillomavirus 18 (HPV18) was utilised to direct tissue-specific expression in a number of cell types. Expression was examined in three cervical carcinoma cell lines: HeLa (HPV18 positive), SiHa (HPV16 positive), and C33A cells (HPV negative); the epithelial cell line, H1299; and the foetal fibroblast cell line, MRC5, utilising a luciferase expression vector. Expression was highest in the cervical cell lines by a factor of at least 80. The effect of a number of mutations in the P105 promoter on expression levels was examined. Three deletion constructs of the long control region (LCR) were investigated: an 800 bp fragment (LCR800), a 400 bp fragment (LCR400), and a 200 bp fragment (LCR200), as well as the full length product LCR of HPV18 (LCR1000). The LCR800 construct of the HPV18 P105 promoter had the highest level of expression in the cervical cell lines and was also highest in the HPV18-positive HeLa cell line. Site-directed mutagenesis was then employed on the LCR800 construct to create four further constructs that each had inactivating mutations in one of the four E2 binding sites (E2BSs). Overall, this study indicated that the LCR800 construct of the HPV18 P105 promoter could be utilised as a tissuerestricted promoter in cervical cancer cells.
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19
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Yamamoto D, Shima K, Matsuo K, Nishioka T, Chen CY, Hu GF, Sasaki A, Tsuji T. Ornithine decarboxylase antizyme induces hypomethylation of genome DNA and histone H3 lysine 9 dimethylation (H3K9me2) in human oral cancer cell line. PLoS One 2010; 5:e12554. [PMID: 20838441 PMCID: PMC2933235 DOI: 10.1371/journal.pone.0012554] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 07/31/2010] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Methylation of CpG islands of genome DNA and lysine residues of histone H3 and H4 tails regulates gene transcription. Inhibition of polyamine synthesis by ornithine decarboxylase antizyme-1 (OAZ) in human oral cancer cell line resulted in accumulation of decarboxylated S-adenosylmethionine (dcSAM), which acts as a competitive inhibitor of methylation reactions. We anticipated that accumulation of dcSAM impaired methylation reactions and resulted in hypomethylation of genome DNA and histone tails. METHODOLOGY/PRINCIPAL FINDINGS Global methylation state of genome DNA and lysine residues of histone H3 and H4 tails were assayed by Methylation by Isoschizomers (MIAMI) method and western blotting, respectively, in the presence or absence of OAZ expression. Ectopic expression of OAZ mediated hypomethylation of CpG islands of genome DNA and histone H3 lysine 9 dimethylation (H3K9me2). Protein level of DNA methyltransferase 3B (DNMT3B) and histone H3K9me specific methyltransferase G9a were down-regulated in OAZ transfectant. CONCLUSIONS/SIGNIFICANCE OAZ induced hypomethylation of CpG islands of global genome DNA and H3K9me2 by down-regulating DNMT3B and G9a protein level. Hypomethylation of CpG islands of genome DNA and histone H3K9me2 is a potent mechanism of induction of the genes related to tumor suppression and DNA double strand break repair.
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Affiliation(s)
- Daisuke Yamamoto
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Oral and Maxillofacial Surgery, Okayama University Graduate School, Okayama, Japan
| | - Kaori Shima
- Center for Molecular Oncologic Pathology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Kou Matsuo
- Division of Oral Pathology, Department of Biosciences, Kyushu Dental College, Kitakyushu, Japan
| | - Takashi Nishioka
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chang Yan Chen
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Guo-fu Hu
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Akira Sasaki
- Department of Oral and Maxillofacial Surgery, Okayama University Graduate School, Okayama, Japan
| | - Takanori Tsuji
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
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20
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Abstract
Human DNA topoisomerase IIbeta-binding protein 1 (TopBP1) and its orthologues in other organisms are proteins consisting of multiple BRCT modules that have acquired several functions during evolution. These proteins execute their tasks by interacting with a great variety of proteins involved in nuclear processes. TopBP1 is an essential protein that has numerous roles in the maintenance of the genomic integrity. In particular, it is required for the activation of ATM and Rad3-related (ATR), a vital regulator of DNA replication and replication stress response. The orthologues from yeast to human are involved in DNA replication and DNA damage response, while only proteins from higher eukaryotes are also involved in complex regulation of transcription, which is related to cell proliferation, damage response and apoptosis. We review here the recent progress in research aimed at elucidating the multiple cellular functions of TopBP1, focusing on metazoan systems.
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21
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Search for cellular partners of human papillomavirus type 16 E2 protein. Arch Virol 2008; 153:983-90. [PMID: 18305892 DOI: 10.1007/s00705-008-0061-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 01/25/2008] [Indexed: 12/14/2022]
Abstract
Human papillomaviruses (HPVs) are small, double-stranded DNA viruses that infect cutaneous and mucosal epithelia. Type 16 (HPV16) displays tropism to genital epithelia, giving rise to genital warts and cervical intraepithelial neoplasia (CIN), which is a precursor lesion to invasive carcinoma of the cervix. The great majority of human cervical cancers contain integrated HPV DNA where the E2 gene is usually disrupted, suggesting that the loss of the E2 protein is an important step in HPV-induced carcinogenesis. The HPV16 E2 protein is a regulatory protein that seems to be essential for creating favourable conditions for establishment of infection and proper completion of the viral life cycle. Recently, diverse activities of the E2 proteins have been described, but the molecular basis of these processes has not beenfully elucidated. Using a yeast two-hybrid system, we have identified epithelial cellular proteins that bind to the E2 protein of HPV16.
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22
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Donaldson MM, Boner W, Morgan IM. TopBP1 regulates human papillomavirus type 16 E2 interaction with chromatin. J Virol 2007; 81:4338-42. [PMID: 17287259 PMCID: PMC1866123 DOI: 10.1128/jvi.02353-06] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human papillomavirus type 16 (HPV16) E2 regulates transcription from and replication of the viral genome, in association with viral and cellular factors. HPV16 E2 interacts functionally with TopBP1, a cellular protein essential for the initiation of cellular, and potentially viral, DNA replication. This report demonstrates that the absence of TopBP1 results in the redistribution of HPV16 E2 into an alternative cellular protein complex, resulting in enhanced affinity for chromatin. This redistribution does not significantly alter the ability of HPV16 E2 to either activate or repress transcription. We also show colocalization of both proteins on chromatin at late stages of mitosis, suggesting that TopBP1 could be the mitotic chromatin receptor for HPV16 E2. The possible significance of the results for the regulation of the viral life cycle is discussed.
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Affiliation(s)
- Mary M Donaldson
- Institute of Comparative Medicine, Division of Pathological Sciences, University of Glasgow Faculty of Veterinary Medicine, Bearsden Road, Glasgow, G61 1QH Scotland
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23
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Wright R, Dornan E, Donaldson M, Morgan I. TopBP1 contains a transcriptional activation domain suppressed by two adjacent BRCT domains. Biochem J 2006; 400:573-82. [PMID: 16984230 PMCID: PMC1698607 DOI: 10.1042/bj20060831] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
TopBP1 has eight BRCT [BRCA1 (breast-cancer susceptibility gene 1) C-terminus] domains and is involved in initiating DNA replication, and DNA damage checkpoint signalling and repair. Several BRCT-domain-containing proteins involved in mediating DNA repair have transcriptional regulatory domains, and as demonstrated for BRCA1 these regulatory domains are important in mediating the functions of these proteins. These transcriptional regulatory processes involve modification of chromatin, and recent evidence has clearly demonstrated that the ability to modify chromatin plays an important role in regulating DNA damage signalling and repair. Here we report the identification of a TopBP1 transcriptional activation domain that is rich in hydrophobic residues, interspersed with acidic amino acids, characteristics that are typical of transcriptional activation domains identified previously. Two adjacent repressor domains encoded by BRCT2 and BRCT5 silence this activator and experiments suggest that these repressors actively recruit repressor complexes. Both the activator and BRCT2 repressor domains function in yeast. The present study identifies several chromatin modification domains encoded by TopBP1, and the implications of these findings are discussed in the context of the DNA damage response and the understanding of TopBP1 function.
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Affiliation(s)
- Roni H. G. Wright
- Institute of Comparative Medicine, Division of Pathological Sciences, University of Glasgow Faculty of Veterinary Medicine, Garscube Estate, Switchback Road, Glasgow G61 1QH, Scotland U.K
| | - Edward S. Dornan
- Institute of Comparative Medicine, Division of Pathological Sciences, University of Glasgow Faculty of Veterinary Medicine, Garscube Estate, Switchback Road, Glasgow G61 1QH, Scotland U.K
| | - Mary M. Donaldson
- Institute of Comparative Medicine, Division of Pathological Sciences, University of Glasgow Faculty of Veterinary Medicine, Garscube Estate, Switchback Road, Glasgow G61 1QH, Scotland U.K
| | - Iain M. Morgan
- Institute of Comparative Medicine, Division of Pathological Sciences, University of Glasgow Faculty of Veterinary Medicine, Garscube Estate, Switchback Road, Glasgow G61 1QH, Scotland U.K
- To whom correspondence should be addressed (email )
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24
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Sklan EH, Podoly E, Soreq H. RACK1 has the nerve to act: structure meets function in the nervous system. Prog Neurobiol 2006; 78:117-34. [PMID: 16457939 DOI: 10.1016/j.pneurobio.2005.12.002] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2005] [Revised: 11/20/2005] [Accepted: 12/07/2005] [Indexed: 11/26/2022]
Abstract
The receptor for activated protein kinase C 1 (RACK1) is an intracellular adaptor protein. Accumulating evidence attributes to this member of the tryptophan-aspartate (WD) repeat family the role of regulating several major nervous system pathways. Structurally, RACK1 is a seven-bladed-beta-propeller, interacting with diverse proteins having distinct structural folds. When bound to the IP3 receptor, RACK1 regulates intracellular Ca2+ levels, potentially contributing to processes such as learning, memory and synaptic plasticity. By binding to the NMDA receptor, it dictates neuronal excitation and sensitivity to ethanol. When bound to the stress-induced acetylcholinesterase variant AChE-R, RACK1 is implicated in stress responses and behavior, compatible with reports of RACK1 modulations in brain ageing and in various neurodegenerative diseases. This review sheds new light on both the virtues and the variety of neuronal RACK1 interactions and their physiological consequences.
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Affiliation(s)
- Ella H Sklan
- The Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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25
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Garcia V, Furuya K, Carr AM. Identification and functional analysis of TopBP1 and its homologs. DNA Repair (Amst) 2005; 4:1227-39. [PMID: 15897014 DOI: 10.1016/j.dnarep.2005.04.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Revised: 04/11/2005] [Accepted: 04/11/2005] [Indexed: 01/18/2023]
Abstract
The multiple BRCT-domain protein TopBP1 and its yeast homologs have been implicated in many aspects of DNA metabolism, but their molecular functions remain elusive. In this review, we first summarise how the yeast homologs were identified and characterised. We next review the data available from metazoan systems and finally draw parallels with the yeast models. TopBP1 plays important functions in the initiation of DNA replication in all organisms and participates in checkpoint responses both within S phase and following DNA damage. In metazoan systems there is accumulating evidence for additional roles in transcriptional regulation that have not been reported in yeast. Overall, TopBP1 appears to play a key role in integrating different aspects of DNA metabolism, but the mechanistic basis for this remains to be fully explained.
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Affiliation(s)
- Valerie Garcia
- Genome Damage and Stability Center, University of Sussex, Brighton, Sussex BN1 9RQ, UK
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26
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Altundag K, Altundag O, Gundeslioglu O. Human papilloma virus and breast cancer. J Clin Virol 2005; 33:179. [PMID: 15911436 DOI: 10.1016/j.jcv.2004.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Accepted: 11/19/2004] [Indexed: 10/25/2022]
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27
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Altundag O, Altundag K, Morandi P, Gunduz M. Adjuvant targeted therapy with trastuzumab may decrease metastatic capacity in specific group of oropharyngeal cancer patients: downregulation of E-cadherin–catenin complex by cooperative effect of erbB-2 and human papillomavirus type 16 E6/E7 protooncogenes. Med Hypotheses 2004; 63:277-80. [PMID: 15236790 DOI: 10.1016/j.mehy.2004.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Accepted: 03/05/2004] [Indexed: 11/15/2022]
Abstract
Human papillomavirus (HPV) type 16 is causally associated with a subset of oral cancers, predominantly those cancers arising in the oropharynx (OP). Increased HPV16 E6 and E7 oncogene expressions are responsible for the malignant transmission in these cancers. ErbB-2 is the family member most closely implicated in human cancer, where it is overexpressed in about 30% of carcinomas including head and neck squamous cell carcinoma. Coexpressions of E6/E7 and ErbB-2 downregulate E-cadherin and catenin expression, therefore induces metastatic process. Trastuzumab is a humanized monoclonal antibody that recognizes the ErbB-2 protein receptor and breakthrough in the treatment of metastatic breast cancer in combination with chemotherapeutic agents. This antibody is also in clinical testing for adjuvant treatment of breast cancer. We propose that trastuzumab as an adjuvant treatment may decrease process of tumor metastasis in oropharyngeal cancer patients who completed primary treatment (surgery and/or radiotherapy) and show expression of both HPV16 E6/E7 and erbB-2 oncoproteins. In vitro and in vivo studies with trastuzumab in these subgroup of patients may support our hypothesis.
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Affiliation(s)
- Ozden Altundag
- Department of Medical Oncology, Hacettepe University Faculty of Medicine, Sihhiye, Ankara 06100, Turkey
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