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Wild-type p53 enhances efficiency of simian virus 40 large-T-antigen-induced cellular transformation. J Virol 2009; 83:10106-18. [PMID: 19625393 DOI: 10.1128/jvi.00174-09] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Abortive infection of BALB/c mouse embryo fibroblasts differing in p53 gene status (p53(+/+) versus p53(-/)(-)) with simian virus 40 (SV40) revealed a quantitatively and qualitatively decreased transformation efficiency in p53(-/-) cells compared to p53(+/+) cells, suggesting a supportive effect of wild-type (wt) p53 in the SV40 transformation process. SV40 transformation efficiency also was low in immortalized p53(-/-) BALB/c 10-1 cells but could be restored to approximately the level in immortalized p53(+/+) BALB/c 3T3 cells by reconstituting wt p53, but not mutant p53 (mutp53), expression. Stable expression of large T antigen (LT) in p53(+/+) 3T3 cells resulted in full transformation, while LT expression in p53(-/-) 10-1 cells could not promote growth in suspension or in soft agar to a significant extent. The helper effect of wt p53 is mediated by its cooperation with LT and resides in the p53 N terminus, as an N-terminally truncated p53 (DeltaNp53) could not rescue the p53-null phenotype. The p53 N terminus serves as a scaffold for recruiting transcriptional regulators like p300/CBP and Mdm2 into the LT-p53 complex. Consequently, LT affected global and specific gene expression in p53(+/+) cells significantly more than in p53(-/-) cells. Our data suggest that recruitment of transcriptional regulators into the LT-p53 complex may help to modify cellular gene expression in response to the needs of cellular transformation.
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2
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Simian virus 40 large T antigen disrupts genome integrity and activates a DNA damage response via Bub1 binding. J Virol 2008; 83:117-27. [PMID: 18922873 DOI: 10.1128/jvi.01515-08] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Simian virus 40 (SV40) large T antigen (LT) is a multifunctional protein that is important for viral replication and oncogenic transformation. Previously, infection of monkey or human cells with SV40 was shown to lead to the induction of DNA damage response signaling, which is required for efficient viral replication. However, it was not clear if LT is sufficient to induce the damage response and, if so, what the genetic requirements and functional consequences might be. Here, we show that the expression of LT alone, without a replication origin, can induce key DNA damage response markers including the accumulation of gamma-H2AX and 53BP1 in nuclear foci. Other DNA damage-signaling components downstream of ATM/ATR kinases were induced, including chk1 and chk2. LT also bound the Claspin mediator protein, which normally facilitates the ATR activation of chk1 and monitors cellular replication origins. Stimulation of the damage response by LT depends mainly on binding to Bub1 rather than to the retinoblastoma protein. LT has long been known to stabilize p53 despite functionally inactivating it. We show that the activation of a DNA damage response by LT via Bub1 appears to play a major role in p53 stabilization by promoting the phosphorylation of p53 at Ser15. Accompanying the DNA damage response, LT induces tetraploidy, which is also dependent on Bub1 binding. Taken together, our data suggest that LT, via Bub1 binding, breaches genome integrity mechanisms, leading to DNA damage responses, p53 stabilization, and tetraploidy.
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3
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Characteristics of primary and immortalized fibroblast cells derived from the miniature and domestic pigs. BMC Cell Biol 2007; 8:20. [PMID: 17543094 PMCID: PMC1894962 DOI: 10.1186/1471-2121-8-20] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 06/01/2007] [Indexed: 12/20/2022] Open
Abstract
Background The pig, Sus scrofa domestica includes both the miniature and commercial domestic breed. These animals have influenced the human life and economies and have been studied throughout history. Although the miniature breeds are more recent and have increasingly been used in a variety of biomedical studies, their cell lines have rarely been established. Therefore, we sought to establish primary and immortal cell lines derived from both the miniature and domestic pig to better enable insight into possible in vivo growth differences. Results The in vitro lifespan of primary domestic pig fibroblast (PF) and miniature pig fibroblast (MPF) cells using a standard 3T3 protocol was determined. Both of the primary PF and MPF cells were shown to have a two-step replicative senescence barrier. Primary MPF cells exhibited a relatively shorter lifespan and slower proliferation rate compared to those of primary PF cells. Beyond senescence barriers, lifespan-extended PF and MPF cells were eventually established and indicated spontaneous cellular immortalization. In contrast to the immortalized PF cells, immortal MPF cells showed a transformed phenotype and possessed more frequent chromosomal abnormalities and loss of p53 regulatory function. The lifespan of primary MPF and PF cells was extended by inactivation of the p53 function using transduction by SV40LT without any detectable senescent phenotype. Conclusion These results suggest that p53 signaling might be a major determinant for the replicative senescence in the MPF cells that have the shorter lifespan and slower growth rate compared to PF cells in vitro.
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4
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Insinga A, Monestiroli S, Ronzoni S, Carbone R, Pearson M, Pruneri G, Viale G, Appella E, Pelicci P, Minucci S. Impairment of p53 acetylation, stability and function by an oncogenic transcription factor. EMBO J 2004; 23:1144-54. [PMID: 14976551 PMCID: PMC380970 DOI: 10.1038/sj.emboj.7600109] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Accepted: 01/08/2004] [Indexed: 11/09/2022] Open
Abstract
Mutations of p53 are remarkably rare in acute promyelocytic leukemias (APLs). Here, we demonstrate that the APL-associated fusion proteins PML-RAR and PLZF-RAR directly inhibit p53, allowing leukemic blasts to evade p53-dependent cancer surveillance pathways. PML-RAR causes deacetylation and degradation of p53, resulting in repression of p53 transcriptional activity, and protection from p53-dependent responses to genotoxic stress. These phenomena are dependent on the expression of wild-type PML, acting as a bridge between p53 and PML-RAR. Recruitment of histone deacetylase (HDAC) to p53 and inhibition of p53 activity were abrogated by conditions that either inactivate HDACs or trigger HDAC release from the fusion protein, implicating recruitment of HDAC by PML-RAR as the mechanism underlying p53 inhibition.
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Affiliation(s)
- Alessandra Insinga
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Silvia Monestiroli
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- IFOM-FIRC Institute, Via Serio, Milan, Italy
| | - Simona Ronzoni
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Roberta Carbone
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Mark Pearson
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Giancarlo Pruneri
- Department of Pathology, European Institute of Oncology, Milan, Italy
| | - Giuseppe Viale
- Department of Pathology, European Institute of Oncology, Milan, Italy
| | - Ettore Appella
- Laboratory of Cell Biology, National Cancer Institute, Bethesda MD, USA
| | - PierGiuseppe Pelicci
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- IFOM-FIRC Institute, Via Serio, Milan, Italy
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy. Tel.: + +39 02 57489838; Fax: + +39 02 57489851; E-mail:
| | - Saverio Minucci
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Via Celoria 26, Milan, Italy
- Tel.: + +39 02 57489835; Fax: + +39 02 57489851; E-mail:
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5
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Beauséjour CM, Krtolica A, Galimi F, Narita M, Lowe SW, Yaswen P, Campisi J. Reversal of human cellular senescence: roles of the p53 and p16 pathways. EMBO J 2003; 22:4212-22. [PMID: 12912919 PMCID: PMC175806 DOI: 10.1093/emboj/cdg417] [Citation(s) in RCA: 965] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Telomere erosion and subsequent dysfunction limits the proliferation of normal human cells by a process termed replicative senescence. Replicative senescence is thought to suppress tumorigenesis by establishing an essentially irreversible growth arrest that requires activities of the p53 and pRB tumor suppressor proteins. We show that, depending on expression of the pRB regulator p16, replicative senescence is not necessarily irreversible. We used lentiviruses to express specific viral and cellular proteins in senescent human fibroblasts and mammary epithelial cells. Expression of telomerase did not reverse the senescence arrest. However, cells with low levels of p16 at senescence resumed robust growth upon p53 inactivation, and limited growth upon expression of oncogenic RAS. In contrast, cells with high levels of p16 at senescence failed to proliferate upon p53 inactivation or RAS expression, although they re-entered the cell cycle without growth after pRB inactivation. Our results indicate that the senescence response to telomere dysfunction is reversible and is maintained primarily by p53. However, p16 provides a dominant second barrier to the unlimited growth of human cells.
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Affiliation(s)
- Christian M Beauséjour
- Lawrence Berkeley National Laboratory, MS 84-171, 1 Cyclotron Road, Berkeley, CA 94720, USA
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6
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Sladek TL, Laffin J, Lehman JM, Jacobberger JW. A subset of cells expressing SV40 large T antigen contain elevated p53 levels and have an altered cell cycle phenotype. Cell Prolif 2001; 33:115-25. [PMID: 10845255 PMCID: PMC6496574 DOI: 10.1046/j.1365-2184.2000.00168.x] [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: 11/20/2022] Open
Abstract
Cells transformed by the simian virus 40 (SV40) large T antigen (Tag) contain elevated levels of cellular p53 protein. To quantify this relationship, levels of p53 were measured in NIH 3T3 cells that expressed different concentrations of Tag. Using immunoblotting, average p53 levels were shown to increase linearly with Tag concentrations in these cell lines. Single-cell measurements were also performed using flow cytometry to measure p53 immunofluorescence. Surprisingly, the flow cytometry experiments showed that two distinct cell populations, based on p53 content, were present in cells expressing high levels of Tag. One cell population contained elevated p53 levels. A second population did not contain elevated p53, even though high concentrations of Tag were present in the cells. This latter cell population did not appear to arise because of mutations in either Tag or p53. The two cell populations also had phenotypic differences. In exponentially growing cells, Tag alters the cell cycle distribution (decreases the percentage of G1 phase cells and increases the percentages of S and G2 + M phase cells). This phenotype was maximum in the cell population containing elevated p53. A lesser phenotype was found in the cell population that did not contain elevated p53. These data show, firstly, that cells can express significant levels of Tag and not contain elevated levels of p53 and, secondly, that elevated p53 correlates with the altered cell cycle distribution produced by Tag in growing cells.
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Affiliation(s)
- T L Sladek
- Department of Microbiology and Immunology, Finch University of Health Sciences, The Chicago Medical School, North Chicago, IL 60064, USA.
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7
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Pise-Masison CA, Mahieux R, Jiang H, Ashcroft M, Radonovich M, Duvall J, Guillerm C, Brady JN. Inactivation of p53 by human T-cell lymphotropic virus type 1 Tax requires activation of the NF-kappaB pathway and is dependent on p53 phosphorylation. Mol Cell Biol 2000; 20:3377-86. [PMID: 10779327 PMCID: PMC85630 DOI: 10.1128/mcb.20.10.3377-3386.2000] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
p53 plays a key role in guarding cells against DNA damage and transformation. We previously demonstrated that the human T-cell lymphotropic virus type 1 (HTLV-1) Tax can inactivate p53 transactivation function in lymphocytes. The present study demonstrates that in T cells, Tax-induced p53 inactivation is dependent upon NF-kappaB activation. Analysis of Tax mutants demonstrated that Tax inactivation of p53 function correlates with the ability of Tax to induce NF-kappaB but not p300 binding or CREB transactivation. The Tax-induced p53 inactivation can be overcome by overexpression of a dominant IkappaB mutant. Tax-NF-kappaB-induced p53 inactivation is not due to p300 squelching, since overexpression of p300 does not recover p53 activity in the presence of Tax. Further, using wild-type and p65 knockout mouse embryo fibroblasts (MEFs), we demonstrate that the p65 subunit of NF-kappaB is critical for Tax-induced p53 inactivation. While Tax can inactivate endogenous p53 function in wild-type MEFs, it fails to inactivate p53 function in p65 knockout MEFs. Importantly, Tax-induced p53 inactivation can be restored by expression of p65 in the knockout MEFs. Finally, we present evidence that phosphorylation of serines 15 and 392 correlates with inactivation of p53 by Tax in T cells. This study provides evidence that the divergent NF-kappaB proliferative and p53 cell cycle arrest pathways may be cross-regulated at several levels, including posttranslational modification of p53.
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Affiliation(s)
- C A Pise-Masison
- Virus Tumor Biology Section, Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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8
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Gire V, Wynford-Thomas D. Reinitiation of DNA synthesis and cell division in senescent human fibroblasts by microinjection of anti-p53 antibodies. Mol Cell Biol 1998; 18:1611-21. [PMID: 9488478 PMCID: PMC108876 DOI: 10.1128/mcb.18.3.1611] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In human fibroblasts, growth arrest at the end of the normal proliferative life span (induction of senescence) is dependent on the activity of the tumor suppressor protein p53. In contrast, once senescence has been established, it is generally accepted that reinitiation of DNA synthesis requires loss of multiple suppressor pathways, for example, by expression of Simian virus 40 (SV40) large T antigen, and that even this will not induce complete cell cycle traverse. Here we have used microinjection of monoclonal antibodies to the N terminus of p53, PAb1801 and DO-1, to reinvestigate the effect of blocking p53 function in senescent human fibroblasts. Unexpectedly, we found that both antibodies induce senescent cells to reenter S phase almost as efficiently as SV40, accompanied by a reversion to the "young" morphology. Furthermore, this is followed by completion of the cell division cycle, as shown by the appearance of mitoses, and by a four- to fivefold increase in cell number 9 days after injection. Immunofluorescence analysis showed that expression of the p53-inducible cyclin/kinase inhibitor p21sdi1/WAF1 was greatly diminished by targeting p53 with either PAb1801 or DO-1 but remained high and, moreover, still p53 dependent in cells expressing SV40 T antigen. As previously observed for induction, the maintenance of fibroblast senescence therefore appears to be critically dependent on functional p53. We suggest that the previous failure to observe this by using SV40 T-antigen mutants to target p53 was most probably due to incomplete abrogation of p53 function.
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Affiliation(s)
- V Gire
- Department of Pathology, University of Wales College of Medicine, Cardiff, United Kingdom
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9
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Pise-Masison CA, Choi KS, Radonovich M, Dittmer J, Kim SJ, Brady JN. Inhibition of p53 transactivation function by the human T-cell lymphotropic virus type 1 Tax protein. J Virol 1998; 72:1165-70. [PMID: 9445014 PMCID: PMC124592 DOI: 10.1128/jvi.72.2.1165-1170.1998] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiologic agent for adult T-cell leukemia. HTLV-1 transforms lymphocytes, and there is increasing evidence that the virus-encoded protein, Tax, plays a primary role in viral transformation. We have shown that wild-type p53 in HTLV-1-transformed cells is stabilized. This study was initiated to directly analyze whether the p53 in HTLV-1-transformed cell lines was transcriptionally active and to identify the viral gene product responsible for stabilization and inactivation. Transfection experiments using a p53-responsive reporter plasmid and gamma-irradiation studies demonstrate that the wild-type p53 in HTLV-1-transformed cell lines is not fully active. Further, we demonstrate that the HTLV-1-transforming protein, Tax, stabilizes and inactivates p53 function. Cotransfection of Tax with p53 results in a greater than 10-fold reduction in p53 transcription activity. Using Ga14-p53 fusion proteins, we demonstrate that Tax inhibition of p53 transactivation function is independent of sequence-specific DNA binding. Moreover, Tax inhibits p53 function by interfering with the activity of the N-terminal activation domain (amino acids 1 to 52). We conclude that Tax is involved in the inactivation of p53 function and stabilization of p53 in HTLV-1-infected cells. The functional interference of p53 function by Tax may be important for transformation and leukemogenesis.
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Affiliation(s)
- C A Pise-Masison
- Laboratory of Receptor Biology and Gene Expression, Division of Basic Sciences, National Cancer Institute, Bethesda, Maryland 20892, USA
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10
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Henning W, Rohaly G, Kolzau T, Knippschild U, Maacke H, Deppert W. MDM2 is a target of simian virus 40 in cellular transformation and during lytic infection. J Virol 1997; 71:7609-18. [PMID: 9311842 PMCID: PMC192109 DOI: 10.1128/jvi.71.10.7609-7618.1997] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Phosphopeptide analyses of the simian virus 40 (SV40) large tumor antigen (LT) in SV40-transformed rat cells, as well as in SV40 lytically infected monkey cells, showed that gel-purified LT that was not complexed to p53 (free LT) and p53-complexed LT differed substantially in their phosphorylation patterns. Most significantly, p53-complexed LT contained phosphopeptides not found in free LT. We show that these additional phosphopeptides were derived from MDM2, a cellular antagonist of p53, which coprecipitated with the p53-LT complexes, probably in a trimeric LT-p53-MDM2 complex. MDM2 also quantitatively bound the free p53 in SV40-transformed cells. Free LT, in contrast, was not found in complex with MDM2, indicating a specific targeting of the MDM2 protein by SV40. This specificity is underscored by significantly different phosphorylation patterns of the MDM2 proteins in normal and SV40-transformed cells. Furthermore, the MDM2 protein, like p53, becomes metabolically stabilized in SV40-transformed cells. This suggests the possibility that the specific targeting of MDM2 by SV40 is aimed at preventing MDM2-directed proteasomal degradation of p53 in SV40-infected and -transformed cells, thereby leading to metabolic stabilization of p53 in these cells.
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Affiliation(s)
- W Henning
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Hamburg, Germany
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11
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Grötzinger T, Jensen K, Guldner HH, Sternsdorf T, Szostecki C, Schwab M, Savelyeva L, Reich B, Will H. A highly amplified mouse gene is homologous to the human interferon-responsive Sp100 gene encoding an autoantigen associated with nuclear dots. Mol Cell Biol 1996; 16:1150-6. [PMID: 8622659 PMCID: PMC231097 DOI: 10.1128/mcb.16.3.1150] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In human cells, three proteins are currently known to colocalize in di screte nuclear domains (designated nuclear dots): Sp100, a transcription-activating protein autoantigenic primarily in patients with primary biliary cirrhosis; PML, a tumor suppressor protein involved in development of acute promyelocytic leukemia; and NDP52, a protein of unknown function. Here we report sequence similarities between the Sp100 protein and a putative protein encoded by a highly amplified mouse gene which is visible as an inherited homogeneously staining region (HSR) on chromosome 1 of some mouse populations. By in situ hybridization, the Sp100 gene was mapped to locus 2q37, the syntenic region of the HSR on mouse chromosome 1. Unlike the highly amplified mouse gene, Sp100 was found to be a single-copy gene and showed no restriction fragment length polymorphisms. Sequence similarities in the promoter regions and similar exon-intron organizations of the two genes were revealed. As for Sp100, steady-state levels of the mRNAs of the HSR-encoded genes could be greatly increased by interferon (IFN) treatment. As in human cells, IFN treatment led to an enlargement in both size and number of nuclear dots in mouse cells as visualized by immunofluorescence staining with autoimmune sera from patients with primary biliary cirrhosis. These data indicate that a gene located in the inherited HSR of mice, designated mSp100, is homologous to the human Sp100 gene, has a similar gene organization, and responds similarly to IFN treatment.
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Affiliation(s)
- T Grötzinger
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, Germany
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12
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Tiemann F, Zerrahn J, Deppert W. Cooperation of simian virus 40 large and small T antigens in metabolic stabilization of tumor suppressor p53 during cellular transformation. J Virol 1995; 69:6115-21. [PMID: 7666515 PMCID: PMC189508 DOI: 10.1128/jvi.69.10.6115-6121.1995] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Metabolic stabilization of the tumor suppressor p53 is a key event in cellular transformation by simian virus 40 (SV40). Expression of the SV40 large tumor antigen (large T) is necessary but not sufficient for this process, as metabolic stabilization of p53 complexed to large T in abortively SV40-infected cells strictly depends on the cellular systems analyzed (F. Tiemann and W. Deppert, J. Virol. 68:2869-2878, 1994). Comparative analyses of various cells differing in metabolic stabilization of p53 upon abortive infection with SV40 revealed that metabolic stabilization of p53 closely correlated with expression of the SV40 small t antigen (small t) in these cells: 3T3 cells do not express small t and do not stabilize p53 upon infection with wild-type SV40. However, ectopic expression of small t in 3T3 cells provided these cells with the capacity to stabilize p53 upon SV40 infection. Conversely, precrisis mouse embryo cells express small t and mediate metabolic stabilization of p53 upon infection with wild-type SV40. Infection of these cells with an SV40 small-t deletion mutant did not lead to metabolic stabilization of p53. Small-t expression and metabolic stabilization of p53 correlated with an enhanced transformation efficiency by SV40, supporting the conclusion that at least part of the documented helper effect of small t in SV40 transformation is its ability to promote metabolic stabilization of p53 complexed to large T.
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MESH Headings
- 3T3 Cells
- Animals
- Antigens, Polyomavirus Transforming/biosynthesis
- Antigens, Polyomavirus Transforming/isolation & purification
- Antigens, Polyomavirus Transforming/metabolism
- Base Sequence
- Cell Transformation, Neoplastic
- Cells, Cultured
- DNA Primers
- Electrophoresis, Polyacrylamide Gel
- Embryo, Mammalian
- Fibroblasts
- Gene Expression
- Gene Expression Regulation, Viral
- Genes, Viral
- Genes, p53
- Immunoblotting
- Mice
- Mice, Inbred BALB C
- Molecular Sequence Data
- Molecular Weight
- Protein Binding
- RNA, Messenger/analysis
- RNA, Messenger/biosynthesis
- Simian virus 40/genetics
- Simian virus 40/physiology
- Tumor Suppressor Protein p53/isolation & purification
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- F Tiemann
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Hamburg, Germany
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13
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Tiemann F, Deppert W. Stabilization of the tumor suppressor p53 during cellular transformation by simian virus 40: influence of viral and cellular factors and biological consequences. J Virol 1994; 68:2869-78. [PMID: 8151757 PMCID: PMC236775 DOI: 10.1128/jvi.68.5.2869-2878.1994] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
To understand the process and biological significance of metabolic stabilization of p53 during simian virus 40 (SV40)-induced cellular transformation, we analyzed cellular and viral parameters involved in this process. We demonstrate that neither large T expression as such nor the cellular phenotype (normal versus transformed) markedly influence the stability of p53 complexed to large T in SV40 abortively infected BALB/c mouse fibroblasts. In contrast, metabolic stabilization of p53 is an active cellular event, specifically induced by SV40. The ability of SV40 to induce a cellular response leading to stabilization of p53 complexed to large T is independent from the cellular phenotype and greatly varies between different cells. However, metabolic stability was conferred only to p53 in complex with large T, whereas the free p53 in these cells remained metabolically unstable. Comparative analyses of cellular transformation in various cells differing in stability of p53 complexed to large T upon abortive infection with SV40 revealed a strong correlation between the ability of SV40 to induce metabolic stabilization and its transformation efficiency. Our data suggest that metabolic stabilization and the ensuing enhanced levels of p53 are important for initiation and/or maintenance of SV40 transformation.
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Affiliation(s)
- F Tiemann
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Universität Hamburg, Germany
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14
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Knippschild U, Kiefer J, Patschinsky T, Deppert W. Phenotype-specific phosphorylation of simian virus 40 tsA mutant large T antigens in tsA N-type and A-type transformants. J Virol 1991; 65:4414-23. [PMID: 1649337 PMCID: PMC248881 DOI: 10.1128/jvi.65.8.4414-4423.1991] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
To identify molecular differences between simian virus 40 (SV40) tsA58 mutant large tumor antigen (large T) in cells of tsA58 N-type transformants [FR(tsA58)A cells], which revert to the normal phenotype after the cells are shifted to the nonpermissive growth temperature, and mutant large T in tsA58 A-type transformants [FR(tsA58)57 cells], which maintain their transformed phenotype after the temperature shift, we asked whether the biological activity of these mutant large T antigens at the nonpermissive growth temperature might correlate with phosphorylation at specific sites. At the permissive growth temperature, the phosphorylation patterns of the mutant large T proteins in FR(tsA58)A (N-type) cells and in FR(tsA58)57 (A-type) cells were largely indistinguishable from that of wild-type large T in FR(wt648) cells. After a shift to the nonpermissive growth temperature, no significant changes in the phosphorylation patterns of wild-type large T in FR(wt648) or of mutant large T in FR(tsA58)57 (A-type) cells were observed. In contrast, the phosphorylation pattern of mutant large T in FR(tsA58)A (N-type) cells changed in a characteristic manner, leading to an apparent underphosphorylation at specific sites. Phosphorylation of the cellular protein p53 was analyzed in parallel. Characteristic differences in the phosphorylation pattern of p53 were observed when cells of N-type and A-type transformants were kept at 39 degrees C as opposed to 32 degrees C. However, these differences did not relate to the different phenotypes of FR(tsA58)A (N-type) and FR(tsA58)57 (A-type) cells at the nonpermissive growth temperature. Our results, therefore, suggest that phosphorylation of large T at specific sites correlates with the transforming activity of tsA mutant large T in SV40 N-type and A-type transformants. This conclusion was substantiated by demonstrating that the biological properties as well as the phosphorylation patterns of SV40 tsA28 mutant large T in cells of SV40 tsA28 N-type and A-type transformants were similar to those in FR(tsA58)A (N-type) and in FR(tsA58)57 (A-type) cells, respectively. The phenotype-specific phosphorylation of tsA mutant large T in tsA A-type transformants probably is a cellular process induced during establishment of SV40 tsA A-type transformants, since tsA28 A-type transformant cells could be obtained by a large-T-dependent in vitro progression of cells of the tsA28 N-type transformant tsA28.3 (M. Osborn and K. Weber, J. Virol. 15:636-644, 1975).
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Affiliation(s)
- U Knippschild
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Universität Hamburg, Federal Republic of Germany
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Deppert W, Von Der Weth A. Functional interaction of nuclear transport-defective simian virus 40 large T antigen with chromatin and nuclear matrix. J Virol 1990; 64:838-46. [PMID: 2153247 PMCID: PMC249179 DOI: 10.1128/jvi.64.2.838-846.1990] [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: 12/30/2022] Open
Abstract
We analyzed the subcellular distribution of nuclear transport-defective simian virus 40 Lys-128-mutant (cT-3 [R. E. Lanford and J. S. Butel, Cell 37:801-813, 1984] and d10 [D. Kalderon, W. D. Richardson, A. F. Markham, and A. E. Smith, Nature (London) 311:33-38, 1984]) large T antigens in various Lys-128-mutant-transformed rodent cells and in Lys-128-mutant d10-infected TC7 cells. Small but significant amounts of the mutant large T antigens were found in association with nuclear substructures, both in mutant-transformed and in mutant-infected cells. Experiments with TC7 cells made incompetent for cell division by 60Co irradiation supported the assumption that Lys-128-mutant large T antigen did not associate with nuclear components during mitosis but most likely was transported into the nucleus because the Lys-128 mutation was leaky for nuclear transport. Low-level simian virus 40 DNA replication and production of infectious mutant virus progeny in TC7 cells indicated that the association of Lys-128-mutant large T antigen with nuclear substructures is functional.
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Affiliation(s)
- W Deppert
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Universität Hamburg, Federal Republic of Germany
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Stabilization of the p53 transformation-related protein in mouse fibrosarcoma cell lines: effects of protein sequence and intracellular environment. Mol Cell Biol 1989. [PMID: 2529426 DOI: 10.1128/mcb.9.8.3385] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transformation-related protein p53 is normally very labile. The stability of p53 is significantly increased in a number of fibrosarcoma cell lines derived from mouse tumors induced by treatment with physical or chemical agents. In many instances, p53 stabilization is correlated with the ability to form a stable complex with the heat shock protein cognate hsc70. We describe a line in which p53 is very stable yet has no detectable interaction with hsc70. The inability to form such a complex probably resides in the primary structure of the endogenous p53, since introduction of other p53 variants into those cells resulted in the appearance of a p53-hsc70 complex. The factors affecting p53 stability were investigated by stable transfection experiments. The results indicated that the primary structure of the p53 protein is a major determinant of its turnover rate; different p53 variants were degraded at distinct and characteristic rates in a number of transformed cell types. However, at least one p53 variant was degraded differently in nontransformed BALB/c-3T3 than in transformed fibrosarcoma cells, demonstrating that the specific cellular environment can also affect the stability of p53.
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Soussi T, Caron de Fromentel C, Stürzbecher HW, Ullrich S, Jenkins J, May P. Evolutionary conservation of the biochemical properties of p53: specific interaction of Xenopus laevis p53 with simian virus 40 large T antigen and mammalian heat shock proteins 70. J Virol 1989; 63:3894-901. [PMID: 2668561 PMCID: PMC250985 DOI: 10.1128/jvi.63.9.3894-3901.1989] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have investigated the biochemical properties of Xenopus laevis p53. With an in vitro binding assay, we can detect a specific association between X. laevis p53 and simian virus 40 large T antigen. Furthermore, X. laevis p53 expressed in monkey COS cells is stably associated with this viral antigen. Like mammalian p53, X. laevis p53 in complex with simian virus 40 large T antigen exhibits a 20-fold increase of its half-life. On the other hand, X. laevis p53 is unable to associate either in vivo or in vitro with adenovirus type 5 E1B 55-kilodalton protein. We show by an immunological technique that X. laevis p53 forms specific complexes with mammalian hsp72 and hsp73 heat shock proteins only at a temperature well above the optimal growth temperature for X. laevis. Our results suggest that the protein-binding properties of p53 are closely related to the functional activity of the protein.
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Affiliation(s)
- T Soussi
- Unité d'Oncologie Moléculaire, Institut de Recherches Scientifiques sur le Cancer, Villejuif, France
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Halevy O, Hall A, Oren M. Stabilization of the p53 transformation-related protein in mouse fibrosarcoma cell lines: effects of protein sequence and intracellular environment. Mol Cell Biol 1989; 9:3385-92. [PMID: 2529426 PMCID: PMC362384 DOI: 10.1128/mcb.9.8.3385-3392.1989] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The transformation-related protein p53 is normally very labile. The stability of p53 is significantly increased in a number of fibrosarcoma cell lines derived from mouse tumors induced by treatment with physical or chemical agents. In many instances, p53 stabilization is correlated with the ability to form a stable complex with the heat shock protein cognate hsc70. We describe a line in which p53 is very stable yet has no detectable interaction with hsc70. The inability to form such a complex probably resides in the primary structure of the endogenous p53, since introduction of other p53 variants into those cells resulted in the appearance of a p53-hsc70 complex. The factors affecting p53 stability were investigated by stable transfection experiments. The results indicated that the primary structure of the p53 protein is a major determinant of its turnover rate; different p53 variants were degraded at distinct and characteristic rates in a number of transformed cell types. However, at least one p53 variant was degraded differently in nontransformed BALB/c-3T3 than in transformed fibrosarcoma cells, demonstrating that the specific cellular environment can also affect the stability of p53.
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Affiliation(s)
- O Halevy
- Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel
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