1
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Huang Y, Carmichael GG. RNA processing in the polyoma virus life cycle. Front Biosci (Landmark Ed) 2009; 14:4968-77. [PMID: 19482599 DOI: 10.2741/3581] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Not only is gene regulation in polyoma interesting, but it has also proven to be highly informative and illustrative of a number of novel concepts in gene regulation. Of special interest and importance are the mechanisms by which this virus switches from the expression of early gene products to late gene products after the onset of viral DNA replication. This switch is mediated at least in part by changes in transcription elongation and polyadenylation in the late region, and by the formation and editing of dsRNA in the nucleus. In this review we will summarize the regulation of RNA synthesis and processing during polyoma infection, and will point out in particular those aspects that have been most novel.
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Affiliation(s)
- Yingqun Huang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, 300 George Street, New Haven, CT 06511, USA
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2
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Bodily JM, Meyers C. Genetic analysis of the human papillomavirus type 31 differentiation-dependent late promoter. J Virol 2005; 79:3309-21. [PMID: 15731225 PMCID: PMC1075705 DOI: 10.1128/jvi.79.6.3309-3321.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human papillomaviruses infect stratifying squamous epithelia, causing benign and malignant lesions. Upon differentiation of the host keratinocyte, the virus undergoes a dramatic increase in both DNA replication and transcription from the late promoter, leading to expression of late genes and virion morphogenesis. In human papillomavirus type 31 (HPV31), the late promoter is designated p742 and includes multiple start sites embedded within the E7 gene. In this report, we mapped viral DNA elements that control transcriptional activity from p742. Enhancer elements in the viral upstream regulatory region positively regulate this promoter. The region containing the transcriptional start sites is dispensable for activity, and at least two separate elements in the E6/E7 region are capable of supporting transcription. Of these, we mapped one to a 150-bp region of the E7 open reading frame and designate it the core p742 promoter. Using GF109203X, an inhibitor of protein kinase C signaling, we show that p742 activation is independent of viral genome amplification. Finally, we mapped elements in the region of p742 that confer responsiveness to differentiation and show that the upstream regulatory region does not contribute to the differentiation response of p742. These studies are an important step toward understanding the functioning and regulation of this multiple-start promoter.
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Affiliation(s)
- Jason M Bodily
- Department of Microbiology and Immunology H107, P. O. Box 850, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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3
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Zhang S, Magnusson G. Kilham polyomavirus: activation of gene expression and DNA replication in mouse fibroblast cells by an enhancer substitution. J Virol 2001; 75:10015-23. [PMID: 11581370 PMCID: PMC114576 DOI: 10.1128/jvi.75.21.10015-10023.2001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The Kilham strain of polyomavirus (KV) infects vascular endothelial cells in vivo (J. E. Greenlee, Infect. Immun. 26:705-713, 1979), but no permissive cell type for growth of the virus in vitro has been identified. The failure of KV DNA to replicate in mouse fibroblast cells after transfection suggested that viral gene expression had narrow cell specificity. A KV substitution mutant having a part of the regulatory region of KV DNA replaced with a segment of the polyomavirus transcriptional enhancer was constructed. The substitution mutant was able to replicate in transfected 3T3 cells, and the newly replicated viral DNA associated with protein to form particles with the density of virions in CsCl equilibrium gradients. However, these particles were noninfectious when tested on 3T3 cells, suggesting that absorption or uptake of virus particles was defective for these cells. Analysis of early and late promoter activities by luciferase reporter gene expression showed that the enhancer substitution had a moderate positive effect on early gene expression and a large effect on the expression of the late genes. KV large T antigen inhibited the activities of both the wild-type and the substitution mutant early promoter, whereas only the mutant late promoter was activated under the same conditions. A comparison of the KV and polyomavirus large T antigens showed that they were not interchangeable in the initiation of KV and polyomavirus DNA synthesis. Furthermore, the wild-type KV origin of DNA replication was less active than the mutant structure in the presence of saturating amounts of KV large T antigen. Together, our data demonstrate several differences between the two types of large T antigen in their interactions with cellular proteins.
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Affiliation(s)
- S Zhang
- Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
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4
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Chen L, Fluck MM. Role of middle T-small T in the lytic cycle of polyomavirus: control of the early-to-late transcriptional switch and viral DNA replication. J Virol 2001; 75:8380-9. [PMID: 11507183 PMCID: PMC115083 DOI: 10.1128/jvi.75.18.8380-8389.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A comparative analysis of the lytic cycle of wild-type polyomavirus and middle T and small T defective mutants was carried out in the A2 genetic background. The results contrast with those obtained in comparisons between the hr-t type and their middle-T small-T-producing partners as previously described (20). The A2-derived mutants were found to share the maturation defect previously described for the hr-t mutants. However, their defect in DNA replication was more acute, resulting in a 5- to 100-fold decrease in the accumulation of viral genomes. Furthermore, their gene expression pattern was affected. A2-derived mutants displayed an early defect resulting in a 4- to 16-h delay in the expression of large T, and an alteration of the early-to-late transcriptional switch. In wild-type A2 infection, this switch is characterized by a large increase in the accumulation of early transcripts followed by late transcripts after the appearance of middle T and small T proteins and the onset of viral DNA replication (L. Chen and M. M. Fluck, J. Virol. 75: 8368-8379, 2001). In the mutant infection, increases in both classes of transcripts were delayed and reduced, but the effect on early transcripts was more pronounced. As has been described previously for the hr-t mutants (E. Goldman, J. Hattori, and T. Benjamin, Cell 13:505-513, 1979), the magnitude of these defects depended upon experimental conditions. Experiments using cytosine beta-arabinofuranoside to reduce genome amplification suggest that the effect of middle T-small T on the transcriptional switch is not solely mediated by the effect of these protein(s) on increasing the number of templates. These data provide the first direct demonstration of an effect of middle T and/or small T in the viral transcription pattern during viral infection. The results agree with previous results obtained with plasmid reporters and with our understanding that the downstream targets of the middle T signaling pathway include three transcription factors that have binding sites in the enhancer domain that play a key regulatory role in the expression of the viral genes.
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Affiliation(s)
- L Chen
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-1101, USA
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5
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Wagner EK, Petroski MD, Pande NT, Lieu PT, Rice M. Analysis of factors influencing kinetics of herpes simplex virus transcription utilizing recombinant virus. Methods 1998; 16:105-16. [PMID: 9774520 DOI: 10.1006/meth.1998.0648] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The herpes simplex virus type 1 (HSV-1) transcription program is a regulated cascade in which early and late phases of gene expression are separated by viral DNA replication. While promoters controlling expression of transcripts encoding immediate-early proteins contain virus-specific cis-acting elements, these are in the context of cellular promoter elements, and the promoters controlling expression of other viral transcripts contain only cellular cis-acting elements. We had developed and continue to refine a general method for the production of recombinant viruses in which modified promoters can be inserted into nonessential loci within the viral genome through homologous recombination. This approach has been especially useful in defining the features of model promoters of the various kinetic classes. Our work suggests that class-specific differences in promoter architecture are critical factors in the ability of the cellular transcription machinery to form stable preinitiation complexes at various phases of infection and, thus, mediate kinetic class-specific transcription. Early (beta) promoters contain a TATA box and upstream activation elements while sequences downstream of the TATA homology are dispensible for transcription. Late transcripts can be catagorized as either leaky-late (beta gamma) or strict late (gamma) depending on whether they are readily detectable prior to viral DNA replication. Promoters controlling both types are clearly distinct from early ones in that sequences near the transcription start site which resemble consensus mammalian initiator elements are required along with the TATA box and activator elements. Strict late promoters do not contain elements upstream of the TATA box but include what appears to be a class specific element downstream of the transcription start site.
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Affiliation(s)
- E K Wagner
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California, 92697-3900, USA.
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6
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Bessis A, Champtiaux N, Chatelin L, Changeux JP. The neuron-restrictive silencer element: a dual enhancer/silencer crucial for patterned expression of a nicotinic receptor gene in the brain. Proc Natl Acad Sci U S A 1997; 94:5906-11. [PMID: 9159173 PMCID: PMC20879 DOI: 10.1073/pnas.94.11.5906] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The neuron-restrictive silencer element (NRSE) has been identified in several neuronal genes and confers neuron specificity by silencing transcription in nonneuronal cells. NRSE is present in the promoter of the neuronal nicotinic acetylcholine receptor beta2-subunit gene that determines its neuron-specific expression in the nervous system. Using transgenic mice, we show that NRSE may either silence or enhance transcription depending on the cellular context within the nervous system. In vitro in neuronal cells, NRSE activates transcription of synthetic promoters when located downstream in the 5' untranslated region, or at less than 50 bp upstream from the TATA box, but switches to a silencer when located further upstream. In contrast, in nonneuronal cells NRSE always functions as a silencer. Antisense RNA inhibition shows that the NRSE-binding protein REST contributes to the activation of transcription in neuronal cells.
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Affiliation(s)
- A Bessis
- Neurobiologie Moléculaire, UA CNRS D1284, Département des Biotechnologies, Institut Pasteur 25/28 rue du Dr Roux, 75724 Paris Cedex 15, France.
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7
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Gendron D, Delbecchi L, Bourgaux-Ramoisy D, Bourgaux P. An enhancer of recombination in polyomavirus DNA. J Virol 1996; 70:4748-60. [PMID: 8676502 PMCID: PMC190412 DOI: 10.1128/jvi.70.7.4748-4760.1996] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Previous work from this laboratory has indicated that intramolecular homologous recombination of polyomavirus (Py) DNA is dependent upon promoter structure or function. In this report, we demonstrate that Py DNA contains not two but three binding sites for transcription factor YY1, all located on the late side of viral origin of replication (ori) and the third well within the VP1 coding sequence. This third site (Y3), which may or may not play a role in transcription regulation, is immediately adjacent to a previously described recombination hot spot (S1/S2). We found that Py replicons carrying an altered Y3 site recombined in a manner suggesting partial inactivation of the S1/S hot spot. Point mutations precluding the binding of YY1 to Y3 in vitro depressed hot spot activity in vivo; however, of the two reciprocal products reflecting recombination at this spot, only that carrying the mutated Y3 site arose at a reduced rate. These results are interpreted in light of a model assuming that recombination occurs within a transcriptionally active viral chromatin tethered to the nuclear matrix by YY1.
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Affiliation(s)
- D Gendron
- Department of Microbiology, The Medical School, Université de Sherbrooke, Québec, Canada
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8
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Martelli F, Iacobini C, Caruso M, Felsani A. Characterization of two novel YY1 binding sites in the polyomavirus late promoter. J Virol 1996; 70:1433-8. [PMID: 8627660 PMCID: PMC189963 DOI: 10.1128/jvi.70.3.1433-1438.1996] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
NF-D is a ubiquitous nuclear factor that has been shown to bind specifically to a DNA element in the polyomavirus regulatory region. In this report, we demonstrate that NF-D is either identical or very similar to a transcription factor that has been variously named YY1, delta, NF-E1, UCRBP, or CF1. Moreover, we show the presence in the polyomavirus genome of a second DNA motif, located 40 bp from the first, which binds YY1/NF-D with high affinity. Both sites lie downstream of the major late transcription initiation sites. By site-directed mutagenesis, we demonstrate that both elements contribute positively to the activity of the late promoter, probably by a cooperative mechanism. We also demonstrate that the requirement of the YY1/NF-D function for late promoter activity varies with the cell line.
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Affiliation(s)
- F Martelli
- Istituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Rome, Italy
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9
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Bessis A, Salmon AM, Zoli M, Le Novère N, Picciotto M, Changeux JP. Promoter elements conferring neuron-specific expression of the beta 2-subunit of the neuronal nicotinic acetylcholine receptor studied in vitro and in transgenic mice. Neuroscience 1995; 69:807-19. [PMID: 8596650 DOI: 10.1016/0306-4522(95)00303-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Several genes encoding subunits of the neuronal nicotinic acetylcholine receptors have been cloned and regulatory elements involved in the transcription of the alpha 2 and alpha 7-subunit genes have been described. Yet, the detailed mechanisms governing the neuron-specific transcription and the spatio-temporal expression pattern of these genes remain largely uninvestigated. The beta 2-subunit is the most widely expressed neuronal nicotinic receptor subunit in the nervous system. We have studied the structural and regulatory properties of the 5' sequence of this gene. A fragment of 1163 bp of upstream sequence is sufficient to drive the cell-specific transcription of a reporter gene in both transient transfection assays and in transgenic mice. Deletion analysis and site-directed mutagenesis of this promoter reveal two negative elements and one positive element. The positively-acting sequence includes one functional E-box. One of the repressor elements is located in the transcribed region and is the NRSE/RE1 sequence already described in promoters of neuronal genes. In this paper, we describe the neuron-specific promoter of the gene encoding the neuronal nicotinic acetylcholine receptor beta 2-subunit.
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Affiliation(s)
- A Bessis
- UA CNRS D1284, Département des Biotechnologies, Institut Pasteur 25/28, Paris, France
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10
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Talmage DA, Freund R, Dubensky T, Salcedo M, Gariglio P, Rangel LM, Dawe CJ, Benjamin TL. Heterogeneity in state and expression of viral DNA in polyoma virus-induced tumors of the mouse. Virology 1992; 187:734-47. [PMID: 1312275 DOI: 10.1016/0042-6822(92)90476-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have examined the state and expression of polyoma viral DNA in representative epithelial and mesenchymal tumors, using a combination of biochemical and in situ methods. Results showed wide variations among tumor types and also in different regions within individual tumors, with respect to copy number of viral DNA, presence or absence of deletions, and expression of early and late viral proteins. Epithelial tumors showed the greatest heterogeneity. High copy free viral DNA, frequently with deletions, was found in all such tumors. A portion of free viral DNA was recoverable as transcriptionally active minichromosomes. Three distinct subpopulations of cells were distinguished by in situ analyses. Type 1 cells showed high copy free viral DNA and expressed the major viral capsid protein VP1; these cells appeared to be at various stages of productive (lytic) viral infection. Some productively infected cells were able to undergo mitosis; in a portion of these cells, VP1 was found in close association with the mitotic spindle. Type 2 cells contained high copy free DNA but did not express VP1; by some unknown mechanism, these cells manifest a post-replication block to late gene expression and lytic infection. Type 3 cells contained only low copy, presumably integrated, viral DNA and expressed no VP1; they thus resemble cells transformed in vitro by the virus. Epithelial tumors contained variable mixtures of these subpopulations, while mesenchymal tumors were composed of Type 3 cells only. Differences in virus-cell interactions are discussed in terms of their possible implications in tumor development.
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Affiliation(s)
- D A Talmage
- Institute of Human Nutrition, Columbia University, New York, New York 10032
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11
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Yoo W, Martin ME, Folk WR. PEA1 and PEA3 enhancer elements are primary components of the polyomavirus late transcription initiator element. J Virol 1991; 65:5391-400. [PMID: 1654447 PMCID: PMC249020 DOI: 10.1128/jvi.65.10.5391-5400.1991] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The circular polyomavirus genome is transcribed from divergent promoter regions. Early mRNAs are initiated from a transcription complex formed at a TATA motif, the site of binding of transcription factor TFIID. Early transcription is promoted at a distance by the viral enhancer, which includes DNA motifs bound by cellular proteins of the PEA1 and PEA3 families of transcription activators. In contrast, the predominant viral late mRNAs are initiated within the viral enhancer, which lacks a TATA motif, near the PEA1 and PEA3 DNA motifs. Here, we demonstrate that these PEA1 and PEA3 binding sites are primary components of an autonomous transcription initiator element (Inr). They cause transcription of most polyomavirus late mRNAs and can direct the transcription of heterologous reporter genes. Alternative roles of these DNA motifs as activators of early mRNA transcription and as an initiator element for late mRNA transcription help explain how polyomavirus gene expression is regulated during lytic growth and provides a model for cellular transcription during development.
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MESH Headings
- Animals
- Antigens, Polyomavirus Transforming/metabolism
- Base Sequence
- Blotting, Northern
- Cell Line
- Core Binding Factor Alpha 1 Subunit
- DNA, Viral/genetics
- DNA, Viral/isolation & purification
- DNA-Binding Proteins/genetics
- Enhancer Elements, Genetic
- Genes, Viral
- Mice
- Models, Genetic
- Molecular Sequence Data
- Polyomavirus/genetics
- Promoter Regions, Genetic
- Proto-Oncogene Proteins c-jun
- RNA, Messenger/genetics
- RNA, Messenger/isolation & purification
- Restriction Mapping
- Transcription Factor AP-2
- Transcription Factors/genetics
- Transcription, Genetic
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Affiliation(s)
- W Yoo
- Department of Biochemistry, University of Missouri, Columbia 65212
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12
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Lanoix J, Tseng RW, Acheson NH. Production of polyomavirus late mRNAs requires sequences near the 5' end of the leader but does not require leader-to-leader splicing. J Virol 1991; 65:4728-34. [PMID: 1651405 PMCID: PMC248929 DOI: 10.1128/jvi.65.9.4728-4734.1991] [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: 12/28/2022] Open
Abstract
Polyomavirus late mRNAs contain multiple copies of a 57-nucleotide leader sequence derived by splicing from multigenome-length late transcripts. Inefficient termination of transcription and inefficient polyadenylation allow accumulation of these giant transcripts. In this report, we show that a viable mutant virus, ins5, which contains an efficient rabbit beta-globin polyadenylation signal, produced late mRNAs whose vast majority contains only one leader. ins5 virus nevertheless produced as much late mRNA as did wild-type virus and grew as well as did wild-type virus in mouse cells. These results demonstrate that leader-to-leader splicing per se is not required for efficient production of late mRNAs or for efficient virus replication. However, we also found that RNAs lacking critical sequences near the 5' end of the leader did not accumulate as mRNAs and that most late transcripts made during the early part of the late phase, when few late mRNAs are produced, initiated downstream of the 5' end of the leader. These results indicate that a sequence element near the 5' end of the leader is required for proper processing, transport, or stability of late mRNAs and that the control of late mRNA production depends in part on the choice of transcription initiation sites at the late promoter.
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Affiliation(s)
- J Lanoix
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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13
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Nilsson M, Osterlund M, Magnusson G. Analysis of polyomavirus enhancer-effect on DNA replication and early gene expression. J Mol Biol 1991; 218:479-83. [PMID: 1850000 DOI: 10.1016/0022-2836(91)90690-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The polyomavirus enhancer is located adjacent to the origin of DNA replication and the transcriptional promoters. It has a cis-acting essential function in the initiation of both viral DNA synthesis and early transcription. The enhancer is activated by the binding of protein factors to specific sites in DNA. Mutants with deletions of the A- or the B-segment of the enhancer were constructed. In mouse 3T6 cells, the transcription of the viral early region was significantly decreased by deletion of the A-segment, but not by deletion of the B-segment. In contrast, the two deletions had a similar, moderately negative effect on viral DNA synthesis. However, the presence of DNA with a wild-type enhancer in doubly transfected cells resulted in very strong interference with the replication, but not with the transcription, of deletion mutant DNA. DNA of the deletion mutants were subjected to site-directed mutagenesis of the remaining enhancer segment. Three non-viable mutants were isolated. All three had base-pair changes in the A-segment affecting immediately adjacent binding sites of cellular protein factors. The mutants had lost the enhancer activity on the early promoter, but only one of them with multiple base substitutions had lost the capacity of DNA replication. Together, the results suggest that different aspects of enhancer function determine the activity in initiation of transcription and replication.
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Affiliation(s)
- M Nilsson
- Department of Medical Virology, Uppsala University, Sweden
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14
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Flavin M, Strauss F. Multiple sequence-specific single-strand-binding proteins for the promoter region of the rat albumin gene. DNA Cell Biol 1991; 10:113-8. [PMID: 1848434 DOI: 10.1089/dna.1991.10.113] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Previous work from our laboratory described a protein that binds to single-stranded DNA in the early promoter of simian virus 40 in a sequence specific fashion. We have now used the gel retardation assay to search for similar sequence-specific single-strand-binding proteins for the promoter region of the rat albumin gene in nuclear extracts of rat hepatoma cells. Several proteins of this kind were detected, three of which are described in the present paper. Two of them bind specifically to the noncoding strand and the third one binds to the coding strand. The most abundant of these proteins binds to a pyrimidine stretch inside the coding region of the gene and appears to be homologous to the previously observed SV40-binding protein. Possible functions for sequence-specific single-strand-binding proteins in transcription are discussed.
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Affiliation(s)
- M Flavin
- Unité INSERM-U56, Hôpital du Kremlin-Bicêtre, France
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15
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Streuli CH, Krauzewicz NS, Griffin BE. Recombination resulting in unusual features in the polyomavirus genome isolated from a murine tumor cell line. J Virol 1990; 64:3570-80. [PMID: 2164586 PMCID: PMC249649 DOI: 10.1128/jvi.64.8.3570-3580.1990] [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: 12/30/2022] Open
Abstract
Polyomavirus-induced tumor formation in the adult natural mouse host has been investigated. Tumors were produced in nude mice with the transformation-defective mutant strain NG18 after a long latency period by apparent activation of a cryptic endogenous transforming viral function. A tumor cell line, designated ScB, was established and characterized. Cells from this morphologically distinct line were unusual in that they grew in soft agar but did not form foci. They were highly tumorigenic. They had a 3.1-kilobase major viral transcript that hybridized to probes derived from regions encoding both the T antigens and the structural proteins. ScB cells expressed polyomavirus small T antigen, a slightly altered middle T antigen, and a truncated large T antigen but no capsid proteins. Middle T antigen preserved its interactions with host proteins of 60 and 37 kilodaltons and with c-src. Analysis of cDNA and genomic clones indicated that the stable viral insert in the ScB genome contained multiple copies of the viral B-enhancer. The genome contained two intragenic inversions which created novel early- to late-strand switches. A simple model for the generation of one inversion is proposed that involves the juxtaposition of two stem-loop structures at an illegitimate recombination site; the location of the inverted segment within the integrated sequence permits use of the viral late polyadenylation signal in early-region transcripts, as confirmed by DNA sequence. A repetitive sequence may facilitate recombination at the other inversion site. Both the biological consequences of the observed rearrangements and the structure of the integrated viral DNA suggest that the recombination events are nonrandom.
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MESH Headings
- Animals
- Base Sequence
- Blotting, Northern
- Blotting, Southern
- Cell Transformation, Viral
- Cells, Cultured
- Chromosome Inversion
- Cloning, Molecular
- DNA, Viral/genetics
- DNA, Viral/isolation & purification
- Female
- Gene Library
- Genes, Viral
- Mice
- Mice, Nude
- Molecular Sequence Data
- Mutation
- Nucleic Acid Conformation
- Nucleic Acid Hybridization
- Polyomavirus/genetics
- RNA, Viral/genetics
- RNA, Viral/isolation & purification
- Recombination, Genetic
- Transcription, Genetic
- Viral Proteins/analysis
- Viral Proteins/genetics
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Affiliation(s)
- C H Streuli
- Department of Virology, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom
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16
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A downstream-element-binding factor facilitates assembly of a functional preinitiation complex at the simian virus 40 major late promoter. Mol Cell Biol 1990. [PMID: 2162478 DOI: 10.1128/mcb.10.7.3635] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent work has shown that many promoters recognized by eucaryotic RNA polymerase II contain essential sequences located downstream of the transcriptional initiation site. We show here that the activity of a promoter element centered 28 base pairs downstream of the simian virus 40 major late initiation site appears to be mediated by a DNA-binding protein, which was isolated by affinity chromatography from HeLa cell nuclear extracts. In the absence of the other components of the transcriptional machinery, the protein bound specifically but weakly to its recognition sequence, with a Kd of approximately 10(-8) M. Analysis of kinetic data showed that mutation of the downstream element decreased the number of functional preinitiation complexes assembled at the promoter without significantly altering the time required for half the complexes to assemble. This suggests that in the absence of the downstream activating protein, preinitiation complexes are at least partially assembled but are not transcriptionally competent.
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17
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Ayer DE, Dynan WS. A downstream-element-binding factor facilitates assembly of a functional preinitiation complex at the simian virus 40 major late promoter. Mol Cell Biol 1990; 10:3635-45. [PMID: 2162478 PMCID: PMC360800 DOI: 10.1128/mcb.10.7.3635-3645.1990] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Recent work has shown that many promoters recognized by eucaryotic RNA polymerase II contain essential sequences located downstream of the transcriptional initiation site. We show here that the activity of a promoter element centered 28 base pairs downstream of the simian virus 40 major late initiation site appears to be mediated by a DNA-binding protein, which was isolated by affinity chromatography from HeLa cell nuclear extracts. In the absence of the other components of the transcriptional machinery, the protein bound specifically but weakly to its recognition sequence, with a Kd of approximately 10(-8) M. Analysis of kinetic data showed that mutation of the downstream element decreased the number of functional preinitiation complexes assembled at the promoter without significantly altering the time required for half the complexes to assemble. This suggests that in the absence of the downstream activating protein, preinitiation complexes are at least partially assembled but are not transcriptionally competent.
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Affiliation(s)
- D E Ayer
- Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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18
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Bergqvist A, Nilsson M, Bondeson K, Magnusson G. Loss of DNA-binding and new transcriptional trans-activation function in polyomavirus large T-antigen with mutation of zinc finger motif. Nucleic Acids Res 1990; 18:2715-20. [PMID: 2160069 PMCID: PMC330756 DOI: 10.1093/nar/18.9.2715] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A putative zinc finger in polyomavirus large T-antigen was investigated. We were unable to demonstrate unequivocally a requirement for zinc in specific DNA-binding using the chelating agent 1, 10-phenanthroline. An involvement of the putative zinc finger in specific DNA-binding was nevertheless suggested by the properties of a mutant protein with a cys----ser replacement in the finger motif. Probably as a result of the defective DNA-binding, the mutant protein had lost its activity in initiation of viral DNA-replication and in negative regulation of viral early transcription. However, the trans-activation of the viral late promoter was normal. The analysis also revealed a previously unrecognized activity of large T-antigen. The mutant protein trans-activated the viral early promoter. In the wild-type protein this activity is probably concealed by the separate, negative regulatory function.
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Affiliation(s)
- A Bergqvist
- Department of Medical Virology, Uppsala University Biomedical Center, Sweden
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19
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Hirano T, Iwakura Y. A novel transcriptional regulatory factor that binds to the polyoma virus enhancer in a developmental stage-specific manner. Biochimie 1990; 72:327-36. [PMID: 2169903 DOI: 10.1016/0300-9084(90)90028-f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
By using gel mobility shift assay, it was shown that the nuclear extract from F9 embryonal carcinoma (EC) cells contains a novel transcriptional regulatory factor, BF-H, that binds to the 5' upstream region of the early gene of polyoma virus. Two binding sites were located in the transcriptional enhancer domain "A" (nucleotide 5034-5041) and in the 5' upstream of the domain "A" (4998-5005), having a consensus motif (AAPuATGG) between them. Combination of in vitro mutagenesis with chloramphenicol acetyltransferase (CAT) assay revealed that BF-H is a positive transcriptional factor. Interestingly, the binding of BF-H disappeared after differentiation of F9 cells by treatment with retinoic acid, whereas BF-H was present in the F9 cells differentiated with both retinoic acid and dibutyryl cyclic AMP (dbcAMP). These observations suggest that BF-H regulates the expression of genes in a developmental stage-specific manner in early embryos of the mouse.
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Affiliation(s)
- T Hirano
- Institute of Medical Science, University of Tokyo, Japan
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20
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Enhancer and promoter elements from simian virus 40 and polyomavirus can substitute for an upstream activation sequence in Saccharomyces cerevisiae. Mol Cell Biol 1990. [PMID: 2154686 DOI: 10.1128/mcb.10.3.947] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ten fragments of higher eucaryotic DNA were tested for upstream activation sequence activity in Saccharomyces cerevisiae by inserting them upstream of a CYC1::lacZ promoter lacking an upstream activation sequence. Fragments containing the 21-base-pair repeat region, the enhancer of simian virus 40 or both strongly stimulated beta-galactosidase synthesis, and three fragments from the polyomavirus enhancer region stimulated moderate levels. Three of the four controls of random DNA sequences failed to stimulate significant levels, and the fourth stimulated moderate levels. The stimulation in all cases was independent of the orientation of the inserted fragment. Two series of clones were examined in which between one and six tandemly arranged copies of a fragment were inserted into the XhoI site of the vector. Very interestingly, we detected an apparent exponential relationship between the number of copies of a fragment and the amount of beta-galactosidase produced. Southern analysis showed that increases in enzyme activity were not a result of increased plasmid copy number. Rather, quantitative S1 nuclease analysis demonstrated that the increases were correlated with steady-state levels of lacZ-specific mRNA. We suggest that there may be an evolutionary relationship between some transcriptional activation sequences in yeast cells and the higher eucaryotic regulatory elements that we tested.
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21
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Axelrod NJ, Carmichael GG, Farabaugh PJ. Enhancer and promoter elements from simian virus 40 and polyomavirus can substitute for an upstream activation sequence in Saccharomyces cerevisiae. Mol Cell Biol 1990; 10:947-57. [PMID: 2154686 PMCID: PMC360941 DOI: 10.1128/mcb.10.3.947-957.1990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Ten fragments of higher eucaryotic DNA were tested for upstream activation sequence activity in Saccharomyces cerevisiae by inserting them upstream of a CYC1::lacZ promoter lacking an upstream activation sequence. Fragments containing the 21-base-pair repeat region, the enhancer of simian virus 40 or both strongly stimulated beta-galactosidase synthesis, and three fragments from the polyomavirus enhancer region stimulated moderate levels. Three of the four controls of random DNA sequences failed to stimulate significant levels, and the fourth stimulated moderate levels. The stimulation in all cases was independent of the orientation of the inserted fragment. Two series of clones were examined in which between one and six tandemly arranged copies of a fragment were inserted into the XhoI site of the vector. Very interestingly, we detected an apparent exponential relationship between the number of copies of a fragment and the amount of beta-galactosidase produced. Southern analysis showed that increases in enzyme activity were not a result of increased plasmid copy number. Rather, quantitative S1 nuclease analysis demonstrated that the increases were correlated with steady-state levels of lacZ-specific mRNA. We suggest that there may be an evolutionary relationship between some transcriptional activation sequences in yeast cells and the higher eucaryotic regulatory elements that we tested.
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Affiliation(s)
- N J Axelrod
- Department of Microbiology, University of Connecticut Health Center, Farmington 06032
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22
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Cahill KB, Roome AJ, Carmichael GG. Replication-dependent transactivation of the polyomavirus late promoter. J Virol 1990; 64:992-1001. [PMID: 2154625 PMCID: PMC249209 DOI: 10.1128/jvi.64.3.992-1001.1990] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
When a plasmid containing the wild-type polyomavirus intergenic regulatory region fused to the bacterial cat gene was introduced into mouse NIH 3T3 cells along with a plasmid coding for the early viral proteins (T antigens), chloramphenicol transacetylase enzyme activity and mRNA levels were increased about 10-fold over levels observed in the absence of early proteins. To investigate this transactivation phenomenon further, 11 specific deletion mutant derivatives of the wild-type parent plasmid were constructed and studied. One mutant (NAL) with a minimal level of chloramphenicol transacetylase expression in the absence of T antigens was capable of being transactivated more than 40-fold. A number of other mutants, however, had little capacity for transactivation. Each of these mutants had in common a defect in large T-antigen-mediated DNA replication. Interestingly, one of the transactivation-defective mutants showed a basal late promoter activity fivefold higher than that of wild type and replicated in mouse cells in the absence of large T antigen. Subsequently, a small deletion abolishing viral DNA replication was introduced into those mutants capable of transactivation. The effect of the second deletion was to eliminate both replication and transactivation. Finally, wild-type and mutant constructs were transfected into Fisher rat F-111 cells in the presence or absence of early proteins. No transactivation or replication was ever observed in these cells. We concluded from these studies that the observed transactivation of the polyomavirus late promoter by one or more of the viral early proteins was due to either higher template concentration resulting from DNA replication or replication-associated changes in template conformation.
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Affiliation(s)
- K B Cahill
- Department of Microbiology, University of Connecticut Health Center, Farmington 06032
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