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Manzetti J, Weissbach FH, Graf FE, Unterstab G, Wernli M, Hopfer H, Drachenberg CB, Rinaldo CH, Hirsch HH. BK Polyomavirus Evades Innate Immune Sensing by Disrupting the Mitochondrial Network and Promotes Mitophagy. iScience 2020; 23:101257. [PMID: 32599557 PMCID: PMC7326741 DOI: 10.1016/j.isci.2020.101257] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 03/16/2020] [Accepted: 06/05/2020] [Indexed: 12/12/2022] Open
Abstract
Immune escape contributes to viral persistence, yet little is known about human polyomaviruses. BK-polyomavirus (BKPyV) asymptomatically infects 90% of humans but causes premature allograft failure in kidney transplant patients. Despite virus-specific T cells and neutralizing antibodies, BKPyV persists in kidneys and evades immune control as evidenced by urinary shedding in immunocompetent individuals. Here, we report that BKPyV disrupts the mitochondrial network and membrane potential when expressing the 66aa-long agnoprotein during late replication. Agnoprotein is necessary and sufficient, using its amino-terminal and central domain for mitochondrial targeting and network disruption, respectively. Agnoprotein impairs nuclear IRF3-translocation, interferon-beta expression, and promotes p62/SQSTM1-mitophagy. Agnoprotein-mutant viruses unable to disrupt mitochondria show reduced replication and increased interferon-beta expression but can be rescued by type-I interferon blockade, TBK1-inhibition, or CoCl2-treatment. Mitochondrial fragmentation and p62/SQSTM1-autophagy occur in allograft biopsies of kidney transplant patients with BKPyV nephropathy. JCPyV and SV40 infection similarly disrupt mitochondrial networks, indicating a conserved mechanism facilitating polyomavirus persistence and post-transplant disease. BK polyomavirus agnoprotein disrupts mitochondrial membrane potential and network Agnoprotein impairs nucleus IRF3 translocation and interferon-β expression Agnoprotein facilitates innate immune evasion during the late viral replication phase Damaged mitochondria are targeted for p62/SQSTM1 autophagy
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Affiliation(s)
- Julia Manzetti
- Transplantation & Clinical Virology, Department Biomedicine (Haus Petersplatz), University of Basel, Petersplatz 10, CH-4009 Basel, Switzerland
| | - Fabian H Weissbach
- Transplantation & Clinical Virology, Department Biomedicine (Haus Petersplatz), University of Basel, Petersplatz 10, CH-4009 Basel, Switzerland
| | - Fabrice E Graf
- Transplantation & Clinical Virology, Department Biomedicine (Haus Petersplatz), University of Basel, Petersplatz 10, CH-4009 Basel, Switzerland
| | - Gunhild Unterstab
- Transplantation & Clinical Virology, Department Biomedicine (Haus Petersplatz), University of Basel, Petersplatz 10, CH-4009 Basel, Switzerland
| | - Marion Wernli
- Transplantation & Clinical Virology, Department Biomedicine (Haus Petersplatz), University of Basel, Petersplatz 10, CH-4009 Basel, Switzerland
| | - Helmut Hopfer
- Institute for Pathology, University Hospital Basel, Basel, Switzerland
| | - Cinthia B Drachenberg
- Departments of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christine Hanssen Rinaldo
- Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway; Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway
| | - Hans H Hirsch
- Transplantation & Clinical Virology, Department Biomedicine (Haus Petersplatz), University of Basel, Petersplatz 10, CH-4009 Basel, Switzerland; Clinical Virology, Laboratory Medicine, University Hospital Basel, Basel, Switzerland; Infectious Diseases & Hospital Epidemiology, University Hospital Basel, Basel, Switzerland.
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Saribas AS, Coric P, Bouaziz S, Safak M. Expression of novel proteins by polyomaviruses and recent advances in the structural and functional features of agnoprotein of JC virus, BK virus, and simian virus 40. J Cell Physiol 2018; 234:8295-8315. [PMID: 30390301 DOI: 10.1002/jcp.27715] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/18/2018] [Indexed: 12/30/2022]
Abstract
Polyomavirus family consists of a highly diverse group of small DNA viruses. The founding family member (MPyV) was first discovered in the newborn mouse in the late 1950s, which induces solid tumors in a wide variety of tissue types that are the epithelial and mesenchymal origin. Later, other family members were also isolated from a number of mammalian, avian and fish species. Some of these viruses significantly contributed to our current understanding of the fundamentals of modern biology such as transcription, replication, splicing, RNA editing, and cell transformation. After the discovery of first two human polyomaviruses (JC virus [JCV] and BK virus [BKV]) in the early 1970s, there has been a rapid expansion in the number of human polyomaviruses in recent years due to the availability of the new technologies and brought the present number to 14. Some of the human polyomaviruses cause considerably serious human diseases, including progressive multifocal leukoencephalopathy, polyomavirus-associated nephropathy, Merkel cell carcinoma, and trichodysplasia spinulosa. Emerging evidence suggests that the expression of the polyomavirus genome is more complex than previously thought. In addition to encoding universally expressed regulatory and structural proteins (LT-Ag, Sm t-Ag, VP1, VP2, and VP3), some polyomaviruses express additional virus-specific regulatory proteins and microRNAs. This review summarizes the recent advances in polyomavirus genome expression with respect to the new viral proteins and microRNAs other than the universally expressed ones. In addition, a special emphasis is devoted to the recent structural and functional discoveries in the field of polyomavirus agnoprotein which is expressed only by JCV, BKV, and simian virus 40 genomes.
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Affiliation(s)
- A Sami Saribas
- Laboratory of Molecular Neurovirology, Department of Neuroscience, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Pascale Coric
- Laboratoire de Cristallographie et RMN Biologiques, Université Paris Descartes, Sorbonne Paris Cité, UMR 8015 CNRS, Paris, France
| | - Serge Bouaziz
- Laboratoire de Cristallographie et RMN Biologiques, Université Paris Descartes, Sorbonne Paris Cité, UMR 8015 CNRS, Paris, France
| | - Mahmut Safak
- Laboratory of Molecular Neurovirology, Department of Neuroscience, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
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Lagatie O, Tritsmans L, Stuyver LJ. The miRNA world of polyomaviruses. Virol J 2013; 10:268. [PMID: 23984639 PMCID: PMC3765807 DOI: 10.1186/1743-422x-10-268] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 08/27/2013] [Indexed: 12/20/2022] Open
Abstract
Polyomaviruses are a family of non-enveloped DNA viruses infecting several species, including humans, primates, birds, rodents, bats, horse, cattle, raccoon and sea lion. They typically cause asymptomatic infection and establish latency but can be reactivated under certain conditions causing severe diseases. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in several cellular processes by binding to and inhibiting the translation of specific mRNA transcripts. In this review, we summarize the current knowledge of microRNAs involved in polyomavirus infection. We review in detail the different viral miRNAs that have been discovered and the role they play in controlling both host and viral protein expression. We also give an overview of the current understanding on how host miRNAs may function in controlling polyomavirus replication, immune evasion and pathogenesis.
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Affiliation(s)
- Ole Lagatie
- Janssen Diagnostics, Turnhoutseweg 30, Beerse 2340, Belgium.
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Sami Saribas A, Abou-Gharbia M, Childers W, Sariyer IK, White MK, Safak M. Essential roles of Leu/Ile/Phe-rich domain of JC virus agnoprotein in dimer/oligomer formation, protein stability and splicing of viral transcripts. Virology 2013; 443:161-76. [PMID: 23747198 DOI: 10.1016/j.virol.2013.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 03/21/2013] [Accepted: 05/03/2013] [Indexed: 10/26/2022]
Abstract
Agnoprotein is one of the key regulatory proteins of polyomaviruses, including JCV, BKV and SV40 and is required for a productive viral life cycle. We have recently reported that agnoprotein forms stable dimer/oligomers mediated by a predicted amphipathic α-helix, spanning amino acids (aa), 17 to 42. Deletion of the α-helix renders a replication incompetent virus. Here, we have further characterized this region by a systematic deletion and substitution mutagenesis and demonstrated that a Leu/Ile/Phe-rich domain, (spanning aa 28-39) within α-helix is indispensable for agnoprotein structure and function. Deletion of aa 30-37 severely affects the dimer/oligomer formation and stable expression of the protein. Mutagenesis data also indicate that the residues, 34-36, may be involved in regulation of the splicing events of JCV transcripts. Collectively, these data suggest that the Leu/Ile/Phe-rich domain plays critical roles in agnoprotein function and thus represents a potential target for developing novel therapeutics against JCV infections.
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Affiliation(s)
- A Sami Saribas
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States
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Suzuki T, Semba S, Sunden Y, Orba Y, Kobayashi S, Nagashima K, Kimura T, Hasegawa H, Sawa H. Role of JC virus agnoprotein in virion formation. Microbiol Immunol 2013; 56:639-46. [PMID: 22708997 DOI: 10.1111/j.1348-0421.2012.00484.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
JC virus (JCV) belongs to the polyomavirus family of double-stranded DNA viruses and causes progressive multifocal leukoencephalopathy in humans. JCV encodes early proteins (large T antigen, small T antigen, and T' antigen) and four late proteins (agnoprotein, and three viral capsid proteins, VP1, VP2, and VP3). In the current study, a novel function for JCV agnoprotein in the morphogenesis of JC virion particles was identified. It was found that mature virions of agnoprotein-negative JCV are irregularly shaped. Sucrose gradient sedimentation and cesium chloride gradient ultracentrifugation analyses revealed that the particles of virus lacking agnoprotein assemble into irregularly sized virions, and that agnoprotein alters the efficiency of formation of VP1 virus-like particles. An in vitro binding assay and immunocytochemistry revealed that agnoprotein binds to glutathione S-transferase fusion proteins of VP1 and that some fractions of agnoprotein colocalize with VP1 in the nucleus. In addition, gel filtration analysis of formation of VP1-pentamers revealed that agnoprotein enhances formation of these pentamers by interacting with VP1. The present findings suggest that JCV agnoprotein plays a role, similar to that of SV40 agnoprotein, in facilitating virion assembly.
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Affiliation(s)
- Tadaki Suzuki
- Division of Molecular Pathobiology, Hokkaido University, Research Center for Zoonosis Control, N20, W10, Kita-ku, Sapporo, 001-0020, Japan
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JC virus agnoprotein enhances large T antigen binding to the origin of viral DNA replication: evidence for its involvement in viral DNA replication. Virology 2012; 433:12-26. [PMID: 22840425 DOI: 10.1016/j.virol.2012.06.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 05/25/2012] [Accepted: 06/11/2012] [Indexed: 10/28/2022]
Abstract
Agnoprotein is required for the successful completion of the JC virus (JCV) life cycle and was previously shown to interact with JCV large T-antigen (LT-Ag). Here, we further characterized agnoprotein's involvement in viral DNA replication. Agnoprotein enhances the DNA binding activity of LT-Ag to the viral origin (Ori) without directly interacting with DNA. The predicted amphipathic α-helix of agnoprotein plays a major role in this enhancement. All three phenylalanine (Phe) residues of agnoprotein localize to this α-helix and Phe residues in general are known to play critical roles in protein-protein interaction, protein folding and stability. The functional relevance of all Phe residues was investigated by mutagenesis. When all were mutated to alanine (Ala), the mutant virus (F31AF35AF39A) replicated significantly less efficiently than each individual Phe mutant virus alone, indicating the importance of Phe residues for agnoprotein function. Collectively, these studies indicate a close involvement of agnoprotein in viral DNA replication.
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Human polyomavirus JC small regulatory agnoprotein forms highly stable dimers and oligomers: implications for their roles in agnoprotein function. Virology 2011; 420:51-65. [PMID: 21920573 DOI: 10.1016/j.virol.2011.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 08/09/2011] [Accepted: 08/19/2011] [Indexed: 11/22/2022]
Abstract
JC virus (JCV) encodes a small basic phosphoprotein from the late coding region called agnoprotein, which has been shown to play important regulatory roles in the viral replication cycle. In this study, we report that agnoprotein forms highly stable dimers and higher order oligomer complexes. This was confirmed by immunoblotting and mass spectrometry studies. These complexes are extremely resistant to strong denaturing agents, including urea and SDS. Central portion of the protein, amino acids spanning from 17 to 42 is important for dimer/oligomer formation. Removal of 17 to 42 aa region from the viral background severely affected the efficiency of the JCV replication. Extracts prepared from JCV-infected cells showed a double banding pattern for agnoprotein in vivo. Collectively, these findings suggest that agnoprotein forms functionally active homodimer/oligomer complexes and these may be important for its function during viral propagation and thus for the progression of PML.
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Sariyer IK, Saribas AS, White MK, Safak M. Infection by agnoprotein-negative mutants of polyomavirus JC and SV40 results in the release of virions that are mostly deficient in DNA content. Virol J 2011; 8:255. [PMID: 21609431 PMCID: PMC3127838 DOI: 10.1186/1743-422x-8-255] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 05/24/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human polyomavirus JC (JCV) is the etiologic agent of a brain disease, known as progressive multifocal leukoencephalopathy (PML). The JCV genome encodes a small multifunctional phospho-protein, agnoprotein, from the late coding region of the virus, whose regulatory functions in viral replication cycle remain elusive. In this work, the functional role of JCV and SV40 agnoproteins in virion release was investigated using a point mutant (Pt) of each virus, where the ATG codon of agnoprotein was mutated to abrogate its expression. RESULTS Analysis of both viral protein expression and replication using Pt mutant of each virus revealed that both processes were substantially down-regulated in the absence of agnoprotein compared to wild-type (WT) virus. Complementation studies in cells, which are constitutively expressing JCV agnoprotein and transfected with the JCV Pt mutant genome, showed an elevation in the level of viral DNA replication near to that observed for WT. Constitutive expression of large T antigen was found to be not sufficient to compensate the loss of agnoprotein for efficient replication of neither JCV nor SV40 in vivo. Examination of the viral release process for both JCV and SV40 Pt mutants showed that viral particles are efficiently released from the infected cells in the absence of agnoprotein but were found to be mostly deficient in viral DNA content. CONCLUSIONS The results of this study provide evidence that agnoprotein plays an important role in the polyomavirus JC and SV40 life cycle. Infection by agnoprotein-negative mutants of both viruses results in the release of virions that are mostly deficient in DNA content.
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Affiliation(s)
- Ilker K Sariyer
- Department of Neuroscience, Laboratory of Molecular Neurovirology, Temple University School of Medicine, 3500 N, Broad Street, Philadelphia, PA 19140, USA
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Abstract
Over 50 years of polyomavirus research has produced a wealth of insights into not only general biologic processes in mammalian cells, but also, how conditions can be altered and signaling systems tweaked to produce transformation phenotypes. In the past few years three new members (KIV, WUV, and MCV) have joined two previously known (JCV and BKV) human polyomaviruses. In this review, we present updated information on general virologic features of these polyomaviruses in their natural host, concentrating on the association of MCV with human Merkel cell carcinoma. We further present a discussion on advances made in SV40 as the prototypic model, which has and will continue to inform our understanding about viruses and cancer.
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Affiliation(s)
- Ole Gjoerup
- Cancer Virology Program, Hillman Cancer Research Pavilion, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
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Clinical polyomavirus BK variants with agnogene deletion are non-functional but rescued by trans-complementation. Virology 2010; 398:12-20. [DOI: 10.1016/j.virol.2009.11.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 08/13/2009] [Accepted: 11/17/2009] [Indexed: 11/24/2022]
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Martini F, Corallini A, Balatti V, Sabbioni S, Pancaldi C, Tognon M. Simian virus 40 in humans. Infect Agent Cancer 2007; 2:13. [PMID: 17620119 PMCID: PMC1941725 DOI: 10.1186/1750-9378-2-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 07/09/2007] [Indexed: 01/01/2023] Open
Abstract
Simian virus 40 (SV40) is a monkey virus that was administered to human populations by contaminated vaccines which were produced in SV40 naturally infected monkey cells. Recent molecular biology and epidemiological studies suggest that SV40 may be contagiously transmitted in humans by horizontal infection, independently from the earlier administration of SV40-contaminated vaccines.SV40 footprints in humans have been found associated at high prevalence with specific tumor types such as brain and bone tumors, mesotheliomas and lymphomas and with kidney diseases, and at lower prevalence in blood samples from healthy donors. Contrasting reports appeared in the literature on the circulation of SV40 in humans by contagious transmission and its association, as a possible etiologic cofactor, with specific human tumors. As a consequence of the conflicting results, a considerable debate has developed in the scientific community. In the present review we consider the main results obtained by different groups investigating SV40 sequences in human tumors and in blood specimens, the putative role of SV40 in the onset/progression of specific human tumors, and comment on the hypotheses arising from these data.
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Affiliation(s)
- Fernanda Martini
- Department of Morphology and Embryology, Section of Cell Biology and Molecular Genetics, School of Medicine, and Center of Biotechnology, University of Ferrara, Via Fossato di Mortara, 64/B. 44100 Ferrara, Italy
| | - Alfredo Corallini
- Department of Experimental and Diagnostic Medicine, Section of Microbiology, University of Ferrara, Via Luigi Borsari, 46. 44100 Ferrara, Italy
| | - Veronica Balatti
- Department of Morphology and Embryology, Section of Cell Biology and Molecular Genetics, School of Medicine, and Center of Biotechnology, University of Ferrara, Via Fossato di Mortara, 64/B. 44100 Ferrara, Italy
| | - Silvia Sabbioni
- Department of Experimental and Diagnostic Medicine, Section of Microbiology, University of Ferrara, Via Luigi Borsari, 46. 44100 Ferrara, Italy
| | - Cecilia Pancaldi
- Department of Morphology and Embryology, Section of Cell Biology and Molecular Genetics, School of Medicine, and Center of Biotechnology, University of Ferrara, Via Fossato di Mortara, 64/B. 44100 Ferrara, Italy
| | - Mauro Tognon
- Department of Morphology and Embryology, Section of Cell Biology and Molecular Genetics, School of Medicine, and Center of Biotechnology, University of Ferrara, Via Fossato di Mortara, 64/B. 44100 Ferrara, Italy
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Frisque RJ, Hofstetter C, Tyagarajan SK. Transforming Activities of JC Virus Early Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 577:288-309. [PMID: 16626044 DOI: 10.1007/0-387-32957-9_21] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Polyomaviruses, as their name indicates, are viruses capable of inducing a variety of tumors in vivo. Members of this family, including the human JC and BK viruses (JCV, BKV), and the better characterized mouse polyomavirus and simian virus 40 (SV40), are small DNA viruses that commandeer a cell's molecular machinery to reproduce themselves. Studies of these virus-host interactions have greatly enhanced our understanding of a wide range of phenomena from cellular processes (e.g., DNA replication and transcription) to viral oncogenesis. The current chapter will focus upon the five known JCV early proteins and the contributions each makes to the oncogenic process (transformation) when expressed in cultured cells. Where appropriate, gaps in our understanding of JCV protein function will be supplanted with information obtained from the study of SV40 and BKV.
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Randhawa P, Vats A, Shapiro R. The pathobiology of polyomavirus infection in man. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 577:148-59. [PMID: 16626033 DOI: 10.1007/0-387-32957-9_10] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This article traces the discovery of polyomaviruses and outlines investigations, which shed light on potential modes of transmission of this increasingly important group of human pathogens. The pathobiology of the virus is summarized with particular reference to interactions with host cell receptors, cell entry, cytoplasmic trafficking, and targeting of the viral genome to the nucleus. This is followed by a discussion of sites of viral latency and factors leading to viral reactivation. Finally, we present biochemical mechanisms that could potentially explain several key elements of tissue pathology characteristic of BKV mediated damage to human kidney.
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White MK, Khalili K. Expression of JC virus regulatory proteins in human cancer: potential mechanisms for tumourigenesis. Eur J Cancer 2005; 41:2537-48. [PMID: 16219459 DOI: 10.1016/j.ejca.2005.08.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
JC virus (JCV) is a human polyomavirus that is the etiologic agent of the fatal demyelinating disease of the central nervous system known as progressive multifocal leukoencephalopathy (PML). JCV is also linked to some tumours of the brain and other organs as evidenced by the presence of JCV DNA sequences and the expression of viral proteins in clinical samples. Since JCV is highly oncogenic in experimental animals and transforms cells in culture, it is possible that JCV contributes to the malignant phenotype of human tumours with which it is associated. JCV encodes three non-capsid regulatory proteins: large T-antigen, small t-antigen and agnoprotein that interact with a number of cellular target proteins and interfere with certain normal cellular functions. In this review, we discuss how JCV proteins deregulate signalling pathways especially ones pertaining to transcriptional regulation and cell cycle control. These effects may be involved in the progression of JCV-associated tumours and may represent potential therapeutic targets.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology, Department of Neuroscience, Temple University School of Medicine, 1900 North 12th Street, MS 015-96, Room 203, Philadelphia, PA 19122, USA
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Khalili K, White MK, Sawa H, Nagashima K, Safak M. The agnoprotein of polyomaviruses: a multifunctional auxiliary protein. J Cell Physiol 2004; 204:1-7. [PMID: 15573377 DOI: 10.1002/jcp.20266] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The late region of the three primate polyomaviruses (JCV, BKV, and SV40) encodes a small, highly basic protein known as agnoprotein. While much attention during the last two decades has focused on the transforming proteins encoded by the early region (small and large T-antigens), it has become increasingly evident that agnoprotein has a critical role in the regulation of viral gene expression and replication, and in the modulation of certain important host cell functions including cell cycle progression and DNA repair. The importance of agnoprotein is underscored by its expression during lytic infection of glial cells by JCV that occurs in progressive multifocal leukoencephalopathy (PML), and also in some JCV-associated human neural tumors particularly medulloblastoma. In this review, we will discuss the structure and function of agnoprotein in the viral life cycle during the course of lytic infection and the consequences of agnoprotein expression for the host cell.
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Affiliation(s)
- Kamel Khalili
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, USA.
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16
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White MK, Khalili K. Polyomaviruses and human cancer: molecular mechanisms underlying patterns of tumorigenesis. Virology 2004; 324:1-16. [PMID: 15183048 DOI: 10.1016/j.virol.2004.03.025] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 03/31/2004] [Indexed: 12/18/2022]
Abstract
Polyomaviruses are DNA tumor viruses with small circular genomes encoding only six proteins including three structural capsid proteins. Despite this simplicity, our understanding of the mechanisms of polyomavirus-mediated tumorigenesis is far from complete. The archetypal primate polyomavirus, SV40, was isolated more than 40 years ago and has been used extensively as a model system for the study of basic eukaryotic cellular processes such as DNA replication and transcription. Two human polyomaviruses have been isolated from clinical samples: JC virus (JCV) and BK virus (BKV). In this review, SV40, JCV, and BKV will be compared based on what is known about their molecular biology from experiments performed in vitro, in cell culture and in laboratory animals. The association of these viruses with clinical tumors is discussed along with the possible roles of these polyomaviruses in the etiology of human malignant disease.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA.
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17
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Farrell ML, Mertz JE. Cell type-specific replication of simian virus 40 conferred by hormone response elements in the late promoter. J Virol 2002; 76:6762-70. [PMID: 12050389 PMCID: PMC136285 DOI: 10.1128/jvi.76.13.6762-6770.2002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The late genes of SV40 are not expressed at significant levels until after the onset of viral DNA replication. We previously identified two hormone response elements (HREs) in the late promoter that contribute to this delay. Mutants defective in these HREs overexpress late RNA at early, but not late, times after transfection of CV-1PD cells. Overexpression of nuclear receptors (NRs) that recognize these HREs leads to repression of the late promoter in a sequence-specific and titratable manner, resulting in a delay in late gene expression. These observations led to a model in which the late promoter is repressed at early times after infection by NRs, with this repression being relieved by titration of these repressors through simian virus 40 (SV40) genome replication to high copy number. Here, we tested this model in the context of the viral life cycle. SV40 genomes containing mutations in either or both HREs that significantly reduce NR binding without altering the coding of any proteins were constructed. Competition for replication between mutant and wild-type viruses in low-multiplicity coinfections indicated that the +1 HRE offered a significant selective advantage to the virus within a few cycles of infection in African green monkey kidney cell lines CV-1, CV-1P, TC-7, MA-134, and Vero but not in CV-1PD' cells. Interestingly, the +55 HRE offered a selective disadvantage in MA-134 cells but had no effect in CV-1, CV-1P, TC-7, Vero, and CV-1PD' cells. Thus, we conclude that these HREs are biologically important to the virus, but in a cell type-specific manner.
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Affiliation(s)
- Michael L Farrell
- McArdle Laboratory for Cancer Research, University of Wisconsin Medical School, Madison, WI 53706-1599, USA
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Farrell ML, Mertz JE. Hormone response element in SV40 late promoter directly affects synthesis of early as well as late viral RNAs. Virology 2002; 297:307-18. [PMID: 12083829 DOI: 10.1006/viro.2002.1478] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously demonstrated that the presence of a hormone response element surrounding the transcription initiation site of the SV40 major late promoter (+1 HRE) confers a replication advantage to the virus in a cell-type-specific manner. We determine here the mechanism by which the +1 HRE confers this advantage by analyzing in detail the various stages of the viral life cycle of wild-type versus a +1 HRE mutant in MA-134 cells. We show that the mutant overexpresses late genes at the expense of early genes at early times after infection. This initial underproduction of early RNA leads, subsequently, to an underproduction of large T-antigen, viral DNA, and infectious virions. We conclude that the +1 HRE is necessary for the proper initial regulation of transcription from the early as well as late promoter so the cascade of subsequent events can be executed for the optimal production of virions.
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Affiliation(s)
- Michael L Farrell
- McArdle Laboratory for Cancer Research, University of Wisconsin Medical School, Madison, Wisconsin 53706-1599, USA
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19
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Safak M, Sadowska B, Barrucco R, Khalili K. Functional interaction between JC virus late regulatory agnoprotein and cellular Y-box binding transcription factor, YB-1. J Virol 2002; 76:3828-38. [PMID: 11907223 PMCID: PMC136065 DOI: 10.1128/jvi.76.8.3828-3838.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human polyomavirus JC virus (JCV) is a causative agent of progressive multifocal leukoencephalopathy which results from lytic infection of glial cells. Although significant progress has been made in understanding the regulation of JCV gene transcription, the mechanism(s) underlying the viral lytic cycle remains largely unknown. We recently reported that the JCV late auxiliary Agnoprotein may have a regulatory role in JCV gene transcription and replication. Here, we investigated its regulatory function in viral gene transcription through its physical and functional interaction with YB-1, a cellular transcription factor which contributes to JCV gene expression in glial cells. Time course studies revealed that Agnoprotein is first detected at day 3 postinfection and that its level increased during the late stage of the infection cycle. Agnoprotein is mainly localized to the cytoplasmic compartment of the infected cell, with high concentrations found in the perinuclear region. While the position of Agnoprotein throughout the infection cycle remained relatively unaltered, the subcellular distribution of YB-1 between the cytoplasm and nucleus changed. Results from coimmunoprecipitation and glutathione S-transferase pull-down experiments revealed that Agnoprotein physically interacts with YB-1 and that the amino-terminal region of Agnoprotein, between residues 1 and 36, is critical for this association. Further investigation of this interaction by functional assays demonstrated that Agnoprotein negatively regulates YB-1-mediated gene transcription and that the region corresponding to residues 1 to 36 of Agnoprotein is important for the observed regulatory event. Taken together, these data demonstrate that the interaction of the viral late regulatory Agnoprotein and cellular Y-box binding factor YB-1 modulates transcriptional activity of JCV promoters.
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Affiliation(s)
- Mahmut Safak
- Laboratory of Molecular Neurovirology, Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
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20
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Safak M, Barrucco R, Darbinyan A, Okada Y, Nagashima K, Khalili K. Interaction of JC virus agno protein with T antigen modulates transcription and replication of the viral genome in glial cells. J Virol 2001; 75:1476-86. [PMID: 11152520 PMCID: PMC114053 DOI: 10.1128/jvi.75.3.1476-1486.2001] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In addition to encoding the structural and regulatory proteins, many viruses encode auxiliary proteins, some of which have been shown to play important roles in lytic and latent states of the viruses. The human neurotropic JC virus (JCV) genome encodes an auxiliary protein called Agno whose function remains unknown. Here, we investigated the functional role of JCV Agno protein on transcription and replication of the viral genome in glial cells. Results from transfection of human glial cells showed that Agno protein suppresses both T-antigen-mediated transcription of the viral late gene promoter and T-antigen-induced replication of viral DNA. Affinity chromatography and coimmunoprecipitation assays demonstrated that the Agno protein and T antigen physically interact with each other. Through the use of a series of deletion mutants, we demonstrated that the T-antigen-interacting region of Agno protein is localized to its amino-terminal half and the Agno-interacting domain of T antigen maps to its central portion. Furthermore, utilizing various Agno deletion mutants in functional studies, we confirmed the importance of the Agno-T antigen interaction in the observed down-modulation of T antigen function upon viral gene transcription and DNA replication by Agno protein. Taken together these data suggest that the Agno protein of JCV, which is produced late during the late phase of the lytic cycle, can physically and functionally interact with the viral early protein, T antigen, and downregulate viral gene expression and DNA replication. The importance of these observations in the lytic cycle of JCV is discussed.
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Affiliation(s)
- M Safak
- Laboratory of Molecular Neurovirology, Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
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21
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Evasion of the immune system by tumor viruses. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0168-7069(01)05014-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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22
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Shishido-Hara Y, Hara Y, Larson T, Yasui K, Nagashima K, Stoner GL. Analysis of capsid formation of human polyomavirus JC (Tokyo-1 strain) by a eukaryotic expression system: splicing of late RNAs, translation and nuclear transport of major capsid protein VP1, and capsid assembly. J Virol 2000; 74:1840-53. [PMID: 10644357 PMCID: PMC111662 DOI: 10.1128/jvi.74.4.1840-1853.2000] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human polyomavirus JC (JCV) can encode the three capsid proteins VP1, VP2, and VP3, downstream of the agnoprotein in the late region. JCV virions are identified in the nucleus of infected cells. In this study, we have elucidated unique features of JCV capsid formation by using a eukaryotic expression system. Structures of JCV polycistronic late RNAs (M1 to M4 and possibly M5 and M6) generated by alternative splicing were determined. VP1 would be synthesized from M2 RNA, and VP2 and VP3 would be synthesized from M1 RNA. The presence of the open reading frame of the agnoprotein or the leader sequence (nucleotides 275 to 409) can decrease the expression level of VP1. VP1 was efficiently transported to the nucleus in the presence of VP2 and VP3 but distributed both in the cytoplasm and in the nucleus in their absence. Mutation analysis indicated that inefficiency in nuclear transport of VP1 is due to the unique structure in the N-terminal sequence, KRKGERK. Within the nucleus, VP1 was localized discretely and identified as speckles in the presence of VP2 and VP3 but distributed diffusely in their absence. These results suggest that VP1 was efficiently transported to the nucleus and localized in the discrete subnuclear regions, possibly with VP2 and VP3. By electron microscopy, recombinant virus particles were identified in the nucleus, and their intranuclear distribution was consistent with distribution of speckles. This system provides a useful model with which to understand JCV capsid formation and the structures and functions of the JCV capsid proteins.
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Affiliation(s)
- Y Shishido-Hara
- Laboratory of Molecular Neurobiology, Human Gene Sciences Center, Tokyo Medical and Dental University, Japan Science and Technology Corporation, Sapporo, Japan.
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23
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An K, Smiley SA, Gillock ET, Reeves WM, Consigli RA. Avian polyomavirus major capsid protein VP1 interacts with the minor capsid proteins and is transported into the cell nucleus but does not assemble into capsid-like particles when expressed in the baculovirus system. Virus Res 1999; 64:173-85. [PMID: 10518713 DOI: 10.1016/s0168-1702(99)00093-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The baculovirus system was used to construct and isolate AcMNPV-VP1, AcMNPV-VP2 and AcMNPV-VP3 recombinant viruses which express the respective avian polyomavirus (APV) structural proteins in Sf9 insect cells. These recombinant AcMNPVs containing APV structural protein genes were utilized to investigate protein-protein interactions between the structural proteins. Immunofluorescence studies utilizing Sf9 cells infected with the AcMNPV-VP1 revealed that the VP1 protein was expressed and localized in the cytoplasm and not transported into the nucleus. When the cells were co-infected with the VP1 and either VP2 or VP3 recombinant viruses, immunofluorescence of the VP1 protein was localized in the nucleus, indicating that the VP1 protein was transported to the nucleus by both the VP2 and VP3 minor proteins. This observation was suggestive of a protein-protein interaction between the expressed proteins. This protein-protein interaction was substantiated by laser scanning confocal microscopy of Sf9 cells that were co-infected with VP1, VP2 and VP3 recombinant viruses. However, the minor proteins could not be co-isolated with VP1 protein by immunoaffinity chromatography using a monoclonal anti-VP1 serum. In addition, capsid-like particles could not be purified either by CsC1 density gradient centrifugation or by immunoaffinity chromatography. VP1 capsomeres were isolated by immunoaffinity chromatography from Sf9 cells infected with AcMNPV-VP1, with or without the minor protein(s), and these capsomeres could assemble in vitro into capsid-like particles. Electron microscopic observation of thin-sectioned Sf9 cells, which were co-infected with VP1, VP2 and VP3 recombinant viruses, demonstrated capsomere-like structures in the nucleus, but capsid-like particles were not observed.
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Affiliation(s)
- K An
- Division of Biology-Ackert Hall, Section of Virology and Oncology, Kansas State University, Manhattan, KS 66506, USA
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24
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Abstract
Genome and pre-genome replication in all animal DNA viruses except poxviruses occurs in the cell nucleus (Table 1). In order to reproduce, an infecting virion enters the cell and traverses through the cytoplasm toward the nucleus. Using the cell's own nuclear import machinery, the viral genome then enters the nucleus through the nuclear pore complex. Targeting of the infecting virion or viral genome to the multiplication site is therefore an essential process in productive viral infection as well as in latent infection and transformation. Yet little is known about how infecting genomes of animal DNA viruses reach the nucleus in order to reproduce. Moreover, this nuclear locus for viral multiplication is remarkable in that the sizes and composition of the infectious particles vary enormously. In this article, we discuss virion structure, life cycle to reproduce infectious particles, viral protein's nuclear import signal, and viral genome nuclear targeting.
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Affiliation(s)
- H Kasamatsu
- Molecular, Cell and Developmental Biology and Molecular Biology Institute, University of California at Los Angeles 90095, USA
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25
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Abstract
Primate polyomavirus genomes all contain an open reading frame at the 5' end of the late coding region called the agnogene. A simian virus 40 agnoprotein with unknown functions has previously been demonstrated. We now show that a BK virus agnoprotein appears in the perinuclear area and cytoplasm late in the infectious cycle. It is phosphorylated in vivo and coimmunoprecipitates with a subset of host cell proteins.
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Affiliation(s)
- C H Rinaldo
- Department of Virology, Institute of Medical Biology, University of Tromso, N-9037 Tromso, Norway
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26
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Barbanti-Brodano G, Martini F, De Mattei M, Lazzarin L, Corallini A, Tognon M. BK and JC human polyomaviruses and simian virus 40: natural history of infection in humans, experimental oncogenicity, and association with human tumors. Adv Virus Res 1998; 50:69-99. [PMID: 9520997 DOI: 10.1016/s0065-3527(08)60806-4] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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27
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Affiliation(s)
- L Jin
- Virus Reference Division, Central Public Health Laboratory, 61 Colindale Avenue, London NW9 5HT
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28
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Ishii N, Minami N, Chen EY, Medina AL, Chico MM, Kasamatsu H. Analysis of a nuclear localization signal of simian virus 40 major capsid protein Vp1. J Virol 1996; 70:1317-22. [PMID: 8551602 PMCID: PMC189950 DOI: 10.1128/jvi.70.2.1317-1322.1996] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The nuclear localization signal of the major structural protein, Vp1, of simian virus 40 was further defined by mutagenesis. The targeting activity was examined in cells microinjected with SV-Vp1 variant viral DNAs bearing either an initiation codon mutation of the agnoprotein or mutations in the Vp1 coding sequence or microinjected with pSG5-Vp1 and pSG5-Vp1 mutant DNAs in which Vp1 or mutant Vp1 is expressed from simian virus 40 early promoter. The Vp1 nuclear localization signal functioned autonomously without agno-protein once the Vp1 protein was synthesized in the cytoplasm. The targeting activity was localized to the amino-terminal 19 residues. While replacement of cysteine 10 with glycine, alanine, or serine did not affect the activity, replacement of arginine 6 with glycine caused the cytoplasmic phenotype. When multiple mutations were introduced among residue 5, 6, 7, 16, 17, or 19, the targeting activity was found to reside in two clusters of basic residues, a cluster of lysine 5, arginine 6, and lysine 7 and a cluster of lysine 16, lysine 17, and lysine 19. The clusters are independently important for nuclear localization activity.
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Affiliation(s)
- N Ishii
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles 90024, USA
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29
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Cripe TP, Delos SE, Estes PA, Garcea RL. In vivo and in vitro association of hsc70 with polyomavirus capsid proteins. J Virol 1995; 69:7807-13. [PMID: 7494292 PMCID: PMC189724 DOI: 10.1128/jvi.69.12.7807-7813.1995] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Members of the 70-kDa family of cellular stress proteins assit in protein folding by preventing inappropriate intra- and intermolecular interactions during normal protein synthesis and transport and when cells are exposed to a variety of environmental stresses. During infection of A31 mouse fibroblasts with polyomavirus, the constitutive form of hsp70, hsc70, coimmunoprecipitated with all three viral capsid proteins (VP1, VP2, and VP3). In addition, the subcellular location of hsc70 changed from cytoplasmic to nuclear late in polyomavirus infection, coincident with the nuclear localization of the viral capsid proteins. VP1 and VP2 expressed in Sf9 insect cells with recombinant baculovirus vectors also coimmunoprecipitated with an hsp70-like protein, and VP1 expressed in Escherichia coli coimmunoprecipitated with the hsp70 homolog DnaK. Capsid proteins expressed by in vitro translation coimmunoprecipitated with the hsc70 protein present in the reticulocyte translation extract. Therefore, the polyomavirus capsid proteins associate with hsc70 during virus infection as well as in recombinant protein expression systems. This association may play a role in preventing the premature assembly of capsids in the cytosol and/or in facilitating the nuclear transport of capsid protein complexes.
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Affiliation(s)
- T P Cripe
- Section of Pediatric Hematology/Oncology, Children's Hospital, Denver, Colorado, USA
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30
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Association of BK and JC Human Polyomaviruses and SV40 with Human Tumors. INFECTIOUS AGENTS AND PATHOGENESIS 1995. [DOI: 10.1007/978-1-4899-1100-1_4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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Bernúes J, Beltrán R, Azorín F. SV40 recombinants carrying a d(CT.GA)22 sequence show increased genomic instability. Gene X 1991; 108:269-74. [PMID: 1660839 DOI: 10.1016/0378-1119(91)90444-g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Repetitive d(CT.GA)n sequences are commonly found in eukaryotic genomic DNA. They are frequently located in sites involved in genetic recombination or in promoter regions. To test for their possible biological function, a d(CT.GA)22 synthetic sequence was introduced into the genome of SV40, since it constitutes an appropriate model system for eukaryotic chromatin. When SV40 infects permissive cells, it proliferates in the form of a minichromosome. The simple repetitive sequence indicated above was inserted at the unique HpaII site of SV40 (at nt 346), and the genomic stability of SV40 recombinants carrying the d(CT.GA)22 sequence (SV/CT22 viruses) was analyzed. Upon serial passage through permissive CV1 cells, SV/CT22 recombinants show an increased production of defective viruses. Generation of SV/CT22 variants is likely to take place via recombination between and within viral molecules. The enhancement of the rate of recombination induced by the repetitive sequence is likely to be related to its known propensity to form triple-stranded structures. Many different variants coexist in the same viral population indicating that the mechanism by which they are produced is not unique. One variant (SV/X), showing a replicative advantage, was characterized in detail. Variant SV/X accounts for a large proportion of the total viral population. Its genomic organization corresponds to a tandem duplication of an early SV40 DNA fragment spanning from approx. nt 3200-nt 160. Variant SV/X contains a duplicated SV40 ori.
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Affiliation(s)
- J Bernúes
- Grupo de Química Macromolecular, Centro de Investigación y Desarrollo CSIC, Barcelona, Spain
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32
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Stacy TP, Chamberlain M, Carswell S, Cole CN. The growth of simian virus 40 (SV40) host range/adenovirus helper function mutants in an African green monkey cell line that constitutively expresses the SV40 agnoprotein. J Virol 1990; 64:3522-6. [PMID: 2161954 PMCID: PMC249622 DOI: 10.1128/jvi.64.7.3522-3526.1990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The simian virus 40 T-antigen carboxy-terminal mutants, dlA2459 and dlA2475, are cell line and temperature dependent for growth and plaque formation in monkey kidney cells. Although these mutants did form plaques on BSC-1 cells at 37 degrees C, they were about fivefold less efficient for plaque formation than wild-type simian virus 40. These mutants did not grow in CV-1 cells and did not synthesize agnoprotein in those cells. CV-1 cells which constitutively express the agnoprotein were permissive for mutant plaque formation. However, late mRNAs, virion proteins, and progeny virion yields did not accumulate to wild-type levels during mutant infection of the agnoprotein-producing cells.
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Affiliation(s)
- T P Stacy
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire
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33
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Spence SL, Tack LC, Wright JH, Carswell S, Pipas JM. Infection of CV1 cells expressing the polyoma virus middle T antigen or the SV40 agnogene product with simian virus 40 host-range mutants. IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY : JOURNAL OF THE TISSUE CULTURE ASSOCIATION 1990; 26:604-11. [PMID: 2162817 DOI: 10.1007/bf02624210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
SV40 viruses bearing mutations at the carboxy-terminus of large T antigen exhibit a host-range phenotype: such viruses are able to grow in BSC monkey kidney cells at 37 degrees C, but give at least 10,000-fold lower yields than wild type virus in BSC cells at 32 degrees C or in CV1 monkey kidney cells at either temperature. The block to infection in the nonpermissive cell type occurs after the onset of viral DNA replication. Infectious progeny virions are produced at very low efficiency. Although capsid proteins are synthesized at decreased levels, this does not account for the magnitude of the defect. Presumably some step of virion assembly or maturation is affected in these mutants. We have previously reported that the viral agnogene product, a protein thought to be involved in viral assembly or release, fails to accumulate in CV1 cells infected with host-range mutants. In polyoma virus the middle T antigen plays a role in virion maturation by influencing the phosphorylation of capsid proteins. In this communication we show that host-range mutants fail to undergo productive infection of CV1 cells expressing middle T antigen. These mutants do form plaques on an agnoprotein-expressing cell line. However, the agnoprotein does not seem to act by correcting the mutational block but rather increases the efficiency of plaque formation.
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Affiliation(s)
- S L Spence
- Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260
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34
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Lowman HB, Behm M, Brown S, Bina M. High-level expression of the simian virus 40 genes LP1, VP1 and VP2 as fusion proteins in Escherichia coli. Gene 1988; 68:23-33. [PMID: 2851492 DOI: 10.1016/0378-1119(88)90595-1] [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] [Indexed: 01/02/2023]
Abstract
The complete sequences of the SV40 agnogene (LP1) and the genes coding for the capsid proteins VP1 and VP2 have been cloned into Escherichia coli expression plasmids. High levels of expression were obtained when the SV40 genes were inserted into the coding sequence of the influenza virus NS1 gene, which has previously been expressed in E. coli. The NS1A-LP1 and NS1A-VP2 chimeric proteins consist of the 81 N-terminal residues of NS1 (designated as peptide NS1A) fused to the complete sequence of the corresponding SV40 protein. The NS1A-VP1 chimera consists of NS1A followed by a linker of nine arbitrary residues and the complete sequence of the SV40 major capsid protein. The observed levels of expression vary considerably among the three chimeric proteins, ranging from approx. 70 micrograms/ml in the case of NS1A-LP1 to approx. 5 micrograms/ml in the case of NS1A-VP2. Cyanogen bromide cleavage of the NS1A-LP1 fusion protein produces fragments with Mrs expected for isolated NS1A and LP1 peptides. A plasmid has also been constructed which expresses the NS1A peptide in high yield.
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Affiliation(s)
- H B Lowman
- Purdue University, Department of Chemistry, West Lafayette, IN 47907
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35
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Rott O, Kröger M, Müller H, Hobom G. The genome of budgerigar fledgling disease virus, an avian polyomavirus. Virology 1988; 165:74-86. [PMID: 2838972 DOI: 10.1016/0042-6822(88)90660-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Budgerigar fledgling disease virus (BFDV) represents the first avian member of the Polyomavirus family. In contrast to mammalian polyomaviruses BFDV exhibits unique biological properties, in particular it is able to cause an acute disease with distinct organ manifestations in affected birds. Here we present the complete nucleotide sequence of the BFDV genome, consisting of 4980 bp. When compared to published nucleotide sequences of other polyomaviruses, the BFDV genome exposes a number of very similar structural features, and undoubtedly qualifies as a member of that family of viruses. The most important differences include a large T antigen remarkably reduced in size, and an origin of replication region with fundamental deviations from the origin structure of all other polyomaviruses. The specific characteristics of the BFDV genome may be used to place this virus into a distinct subgroup within the Polyomavirus family and may give a clue to the elucidation of its extraordinary biological properties.
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Affiliation(s)
- O Rott
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Uniersität Giessen, Federal Republic of Germany
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36
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Barkan A, Welch RC, Mertz JE. Missense mutations in the VP1 gene of simian virus 40 that compensate for defects caused by deletions in the viral agnogene. J Virol 1987; 61:3190-8. [PMID: 3041040 PMCID: PMC255897 DOI: 10.1128/jvi.61.10.3190-3198.1987] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Simian virus 40 mutants lacking sequences in the late leader region are viable but produce smaller plaques than does wild-type virus. Within three passages at low multiplicities of infection, virus stocks of several such mutants accumulated variants that synthesized an altered form of the major virion protein, VP1, having a slightly faster mobility in sodium dodecyl sulfate-polyacrylamide gels than did the wild-type protein. Because these variants overgrew the original virus stocks, we consider them to be second-site revertants. By construction and characterization of a series of recombinants, the second-site mutations were shown to map to at least two different regions of the VP1 gene. Nucleotide sequence analysis indicated that single-amino-acid changes were responsible for the rapid mobility of VP1. When combined in cis with either a wild-type or mutant leader region, these VP1 mutations sped up by 10 to 20 h the time course of accumulation of infectious progeny but not of viral DNA or VP1. LP1, the protein encoded by the agnogene, was shown previously to be necessary for the efficient transport of the virion proteins to the nucleus or for their efficient assembly with viral minichromosomes. The VP1 missense mutations reported here compensate for the lack of LP1 by facilitating this process. On the basis of these findings and findings reported previously by us and others, we hypothesize that LP1 facilitates the formation of infectious particles by inhibiting the polymerization of VP1 molecules until the time they interact with viral minichromosomes; the VP1 mutations reported here compensate for the loss of LP1 by lessening the potential of VP1 for self-polymerization.
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37
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Gharakhanian E, Takahashi J, Kasamatsu H. The carboxyl 35 amino acids of SV40 Vp3 are essential for its nuclear accumulation. Virology 1987; 157:440-8. [PMID: 3029982 DOI: 10.1016/0042-6822(87)90286-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To identify the moiety responsible for nuclear localization of the SV40 structural protein Vp3 in its natural environment, a transfection vector containing the entire coding regions of Vp2, Vp3, and agnoprotein, and one-third of the coding region of Vp1, was constructed. Several mutations were introduced into the plasmid and the subcellular distribution of Vp3 or mutant Vp3 was examined following DEAE-dextran-mediated DNA transfection into TC7 cells. Our study shows that Vp3 is synthesized and is transported into the nucleus in the absence of Vp2, agnoprotein, and intact Vp1. However, in the absence of its carboxyl-terminal 35 amino acids, the truncated Vp3 is limited to a cytoplasmic and perinuclear accumulation. Thus, the carboxyl 35 amino acids of Vp3 are required for its nuclear localization and may contain a nuclear accumulation signal.
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38
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Hou-Jong MH, Larsen SH, Roman A. Role of the agnoprotein in regulation of simian virus 40 replication and maturation pathways. J Virol 1987; 61:937-9. [PMID: 3027418 PMCID: PMC254043 DOI: 10.1128/jvi.61.3.937-939.1987] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Analysis of two agnogene mutants, dl2304 deleted over the entire agnogene and in2379 carrying a 2-base insert, indicated that the mutant phenotype of small plaque formation must be the result of a defect late in the maturation pathway. Both mutants were removed from the pool of molecules available for replication with wild-type kinetics. Whereas dl2304 was somewhat reduced in its rate of progression from chromatin to previrions-virions, in2379, which produced even smaller plaques than dl2304 did, progressed with wild-type kinetics. Therefore, the agnoprotein was not required for progression from chromatin to previrions.
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Resnick J, Shenk T. Simian virus 40 agnoprotein facilitates normal nuclear location of the major capsid polypeptide and cell-to-cell spread of virus. J Virol 1986; 60:1098-106. [PMID: 3023661 PMCID: PMC253355 DOI: 10.1128/jvi.60.3.1098-1106.1986] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The simian virus 40 agnoprotein is a 61-amino-acid, highly basic polypeptide that is coded within the 5' leader of late 16S mRNAs. To better understand agnoprotein function and to more effectively differentiate cis-from trans-acting effects of an agnogene mutation, we constructed a mutant virus that carries a single-base-pair substitution and fails to produce agnoprotein. pm 1493 contains a T/A to A/T transversion at sequence position 335. This mutation converts the agnoprotein initiation codon from ATG to TTG, preventing synthesis of the protein. The mutant displays only a modest growth defect in CV-1P and AGMK cells and no defect in BSC-1 cells. Early-gene expression, DNA replication, synthesis of late viral products, and the kinetics of virion assembly all appear normal in pm 1493-infected CV-1P cells. Immunofluorescent studies, however, indicate that localization of the major capsid polypeptide VP1 is different in mutant- than wild-type virus-infected cells. Furthermore, the lack of agnoprotein led to inefficient release of mature virus from the infected cell. Agnogene mutants could be severely compromised in their ability to propagate in monkeys given their reduced capacity for cell-to-cell spread.
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40
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Carswell S, Alwine JC. Simian virus 40 agnoprotein facilitates perinuclear-nuclear localization of VP1, the major capsid protein. J Virol 1986; 60:1055-61. [PMID: 3023658 PMCID: PMC253345 DOI: 10.1128/jvi.60.3.1055-1061.1986] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The agnoprotein of simian virus 40 (SV40) is a 61-amino-acid protein encoded in the leader of some late mRNAs. In indirect immunofluorescence studies with antisera against SV40 capsid proteins, we show that mutants which make no agnoprotein display abnormal perinuclear-nuclear localization of VP1, the major capsid protein, but not VP2 or VP3, the minor capsid proteins. In wild-type (WT) SV40-infected CV-1P cells, VP1 was found predominantly in the cytoplasm until 36 h postinfection (p.i.), approximately the time that high levels of agnoprotein became detectable under our infection conditions. Thereafter, VP1 localized rapidly to the perinuclear region and to the nucleus. In contrast, in agnoprotein-minus mutant-infected CV-1P cells, perinuclear-nuclear accumulation of VP1 occurred much less efficiently; a significantly greater fraction of cells with predominantly cytoplasmic fluorescence was observed up to 48 h p.i. At 48 and 60 h p.i., more cells with largely perinuclear and little nuclear staining were seen than in WT-infected controls. In similar analyses with stably transfected cell lines constitutively expressing the agnoprotein, VP1 localized to the nucleus before 30 h p.i., regardless of the infecting virus. Delayed nuclear entry of VP1 in a mutant which makes no agnoprotein was also overcome in a revertant which has a second site point mutation in VP1. This suggests that an alteration of VP1 can partially overcome the defect of the agnogene mutation by enhancement of the rate of its own nuclear localization. Taken together, these results indicate that at least one function of the agnoprotein is to enhance the efficiency of perinuclear-nuclear localization of VP1.
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41
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Butel JS, Jarvis DL. The plasma-membrane-associated form of SV40 large tumor antigen: biochemical and biological properties. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 865:171-95. [PMID: 3021222 DOI: 10.1016/0304-419x(86)90027-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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42
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DNA sequence alterations responsible for the synthesis of thermosensitive VP1 in temperature-sensitive BC mutants of simian virus 40. J Virol 1985; 54:646-9. [PMID: 2985830 PMCID: PMC254843 DOI: 10.1128/jvi.54.2.646-649.1985] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The segment of simian virus 40 (SV40) genome which is recognized as the BC domain encodes for the COOH-terminal end of the SV40 major capsid protein VP1. Mutations in this domain lead to the synthesis of a thermosensitive VP1 which fails to assemble mature SV40 at the nonpermissive temperature. We determined the DNA sequences of eight BC mutants and compared them with the DNA sequences of wild-type SV40, polyomavirus, and BK virus. We found that BC11 and BC223 mutations result from changes in nucleotide residues 2367 (A to C) and 2084 (C to T), respectively. The others (i.e., BC208, BC214, BC216, BC217, BC248, and BC274) share the same point mutation at nucleotide 2354 (C to T). These mutations resulted in the following changes: Lys to Thr, His to Tyr, and Pro to Ser at VP1 amino acid residues 290, 196, and 286, respectively.
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