Abstract
Minimal transformants of rat F111 fibroblasts were established after infection with the large T antigen (large T)-encoding retroviral expression vector pZIPTEX (M. Brown, M. McCormack, K. Zinn, M. Farrell, I. Bikel, and D. Livingston, J. Virol. 60:290-293, 1986). Coexpression of small t antigen (small t) in these cells efficiently led to their progression toward a significantly enhanced transformed phenotype. Small t forms a complex with phosphatase 2A and thereby might influence cellular phosphorylation processes, including the phosphorylation of large T. Since phosphorylation can modulate the transforming activity of large T, we asked whether the phosphorylation status of large T in minimally transformed cells might differ from that of large T in maximally transformed FR(wt648) cells and whether it might be altered by coexpression of small t. We found the phosphate turnover on large T in minimally transformed cells significantly different from that in fully transformed cells. This resulted in underphosphorylation of large T in minimally transformed cells at phosphorylation sites previously shown to be involved in the regulation of the transforming activity of large T. However, coexpression of small t in the minimally transformed cells did not alter the phosphate turnover on large T during progression; i.e., it did not induce a change in the steady-state phosphorylation of large T. This suggests that the helper function of small t during the progression of these cells was not mediated by modulating phosphatase 2A activity toward large T.
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- Bikel I., Loeken M. R. Involvement of simian virus 40 (SV40) small t antigen in trans activation of SV40 early and late promoters. J Virol. 1992 Mar;66(3):1489–1494. doi: 10.1128/jvi.66.3.1489-1494.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bikel I., Mamon H., Brown E. L., Boltax J., Agha M., Livingston D. M. The t-unique coding domain is important to the transformation maintenance function of the simian virus 40 small t antigen. Mol Cell Biol. 1986 Apr;6(4):1172–1178. doi: 10.1128/mcb.6.4.1172. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bikel I., Montano X., Agha M. E., Brown M., McCormack M., Boltax J., Livingston D. M. SV40 small t antigen enhances the transformation activity of limiting concentrations of SV40 large T antigen. Cell. 1987 Jan 30;48(2):321–330. doi: 10.1016/0092-8674(87)90435-1. [DOI] [PubMed] [Google Scholar]
- Bossert A., Mulgaonkar P., Rundell K. Interaction of simian virus 40 small-T antigen produced in bacteria with 56K and 32K proteins of animal cells. J Virol. 1985 Oct;56(1):325–327. doi: 10.1128/jvi.56.1.325-327.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bouck N., Beales N., Shenk T., Berg P., di Mayorca G. New region of the simian virus 40 genome required for efficient viral transformation. Proc Natl Acad Sci U S A. 1978 May;75(5):2473–2477. doi: 10.1073/pnas.75.5.2473. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boyle W. J., van der Geer P., Hunter T. Phosphopeptide mapping and phosphoamino acid analysis by two-dimensional separation on thin-layer cellulose plates. Methods Enzymol. 1991;201:110–149. doi: 10.1016/0076-6879(91)01013-r. [DOI] [PubMed] [Google Scholar]
- Brown M., McCormack M., Zinn K. G., Farrell M. P., Bikel I., Livingston D. M. A recombinant murine retrovirus for simian virus 40 large T cDNA transforms mouse fibroblasts to anchorage-independent growth. J Virol. 1986 Oct;60(1):290–293. doi: 10.1128/jvi.60.1.290-293.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chang L. S., Pan S., Pater M. M., Di Mayorca G. Differential requirement for SV40 early genes in immortalization and transformation of primary rat and human embryonic cells. Virology. 1985 Oct 30;146(2):246–261. doi: 10.1016/0042-6822(85)90008-x. [DOI] [PubMed] [Google Scholar]
- Chang L. S., Pater M. M., Hutchinson N. I., di Mayorca G. Transformation by purified early genes of simian virus 40. Virology. 1984 Mar;133(2):341–353. doi: 10.1016/0042-6822(84)90400-8. [DOI] [PubMed] [Google Scholar]
- Choi Y. W., Lee I. C., Ross S. R. Requirement for the simian virus 40 small tumor antigen in tumorigenesis in transgenic mice. Mol Cell Biol. 1988 Aug;8(8):3382–3390. doi: 10.1128/mcb.8.8.3382. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Deppert W., Kurth M., Graessmann M., Graessmann A., Knippschild U. Altered phosphorylation at specific sites confers a mutant phenotype to SV40 wild-type large T antigen in a flat revertant of SV40-transformed cells. Oncogene. 1991 Oct;6(10):1931–1938. [PubMed] [Google Scholar]
- Fanning E. Simian virus 40 large T antigen: the puzzle, the pieces, and the emerging picture. J Virol. 1992 Mar;66(3):1289–1293. doi: 10.1128/jvi.66.3.1289-1293.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Feunteun J., Kress M., Gardes M., Monier R. Viable deletion mutants in the simian virus 40 early region. Proc Natl Acad Sci U S A. 1978 Sep;75(9):4455–4459. doi: 10.1073/pnas.75.9.4455. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Freeman A. E., Igel H. J., Price P. J. I. In vitrol transformation of rat embryo cells: correlations with the known tumorigenic activities of chemicals in rodents. In Vitro. 1975 Mar-Apr;11(2):107–116. doi: 10.1007/BF02624083. [DOI] [PubMed] [Google Scholar]
- Gauchat J. F., Weil R. On the functional roles of simian virus 40 large and small T-antigen in the induction of a mitotic host response. Nucleic Acids Res. 1986 Dec 9;14(23):9339–9351. doi: 10.1093/nar/14.23.9339. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gurney E. G., Tamowski S., Deppert W. Antigenic binding sites of monoclonal antibodies specific for simian virus 40 large T antigen. J Virol. 1986 Mar;57(3):1168–1172. doi: 10.1128/jvi.57.3.1168-1172.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Harlow E., Crawford L. V., Pim D. C., Williamson N. M. Monoclonal antibodies specific for simian virus 40 tumor antigens. J Virol. 1981 Sep;39(3):861–869. doi: 10.1128/jvi.39.3.861-869.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jat P. S., Cepko C. L., Mulligan R. C., Sharp P. A. Recombinant retroviruses encoding simian virus 40 large T antigen and polyomavirus large and middle T antigens. Mol Cell Biol. 1986 Apr;6(4):1204–1217. doi: 10.1128/mcb.6.4.1204. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jog P., Joshi B., Dhamankar V., Imperiale M. J., Rutila J., Rundell K. Mutational analysis of simian virus 40 small-t antigen. J Virol. 1990 Jun;64(6):2895–2900. doi: 10.1128/jvi.64.6.2895-2900.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 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 Aug;65(8):4414–4423. doi: 10.1128/jvi.65.8.4414-4423.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kriegler M., Perez C. F., Hardy C., Botchan M. Transformation mediated by the SV40 T antigens: separation of the overlapping SV40 early genes with a retroviral vector. Cell. 1984 Sep;38(2):483–491. doi: 10.1016/0092-8674(84)90503-8. [DOI] [PubMed] [Google Scholar]
- Livingston D. M., Bradley M. K. The simian virus 40 large T antigen. A lot packed into a little. Mol Biol Med. 1987 Apr;4(2):63–80. [PubMed] [Google Scholar]
- Loeken M. R. Simian virus 40 small t antigen trans activates the adenovirus E2A promoter by using mechanisms distinct from those used by adenovirus E1A. J Virol. 1992 Apr;66(4):2551–2555. doi: 10.1128/jvi.66.4.2551-2555.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Loeken M., Bikel I., Livingston D. M., Brady J. trans-activation of RNA polymerase II and III promoters by SV40 small t antigen. Cell. 1988 Dec 23;55(6):1171–1177. doi: 10.1016/0092-8674(88)90261-9. [DOI] [PubMed] [Google Scholar]
- Martin R. G., Setlow V. P., Edwards C. A., Vembu D. The roles of the simian virus 40 tumor antigens in transformation of Chinese hamster lung cells. Cell. 1979 Jul;17(3):635–643. doi: 10.1016/0092-8674(79)90271-x. [DOI] [PubMed] [Google Scholar]
- Montano X., Millikan R., Milhaven J. M., Newsom D. A., Ludlow J. W., Arthur A. K., Fanning E., Bikel I., Livingston D. M. Simian virus 40 small tumor antigen and an amino-terminal domain of large tumor antigen share a common transforming function. Proc Natl Acad Sci U S A. 1990 Oct;87(19):7448–7452. doi: 10.1073/pnas.87.19.7448. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pallas D. C., Shahrik L. K., Martin B. L., Jaspers S., Miller T. B., Brautigan D. L., Roberts T. M. Polyoma small and middle T antigens and SV40 small t antigen form stable complexes with protein phosphatase 2A. Cell. 1990 Jan 12;60(1):167–176. doi: 10.1016/0092-8674(90)90726-u. [DOI] [PubMed] [Google Scholar]
- Patschinsky T., Knippschild U., Deppert W. Species-specific phosphorylation of mouse and rat p53 in simian virus 40-transformed cells. J Virol. 1992 Jun;66(6):3846–3859. doi: 10.1128/jvi.66.6.3846-3859.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Paucha E., Mellor A., Harvey R., Smith A. E., Hewick R. M., Waterfield M. D. Large and small tumor antigens from simian virus 40 have identical amino termini mapping at 0.65 map units. Proc Natl Acad Sci U S A. 1978 May;75(5):2165–2169. doi: 10.1073/pnas.75.5.2165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pintel D., Bouck N., di Mayorca G. Separation of lytic and transforming functions of the simian virus 40 A region: two mutants which are temperature sensitive for lytic functions have opposite effects on transformation. J Virol. 1981 May;38(2):518–528. doi: 10.1128/jvi.38.2.518-528.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Prives C., Gluzman Y., Winocour E. Cellular and cell-free synthesis of simian virus 40 T-antigens in permissive and transformed cells. J Virol. 1978 Feb;25(2):587–595. doi: 10.1128/jvi.25.2.587-595.1978. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Prives C. The replication functions of SV40 T antigen are regulated by phosphorylation. Cell. 1990 Jun 1;61(5):735–738. doi: 10.1016/0092-8674(90)90179-i. [DOI] [PubMed] [Google Scholar]
- Richter W., Deppert W. The cellular chromatin is an important target for SV40 large T antigen in maintaining the transformed phenotype. Virology. 1990 Feb;174(2):543–556. doi: 10.1016/0042-6822(90)90108-4. [DOI] [PubMed] [Google Scholar]
- Rubin H., Figge J., Bladon M. T., Chen L. B., Ellman M., Bikel I., Farrell M., Livingston D. M. Role of small t antigen in the acute transforming activity of SV40. Cell. 1982 Sep;30(2):469–480. doi: 10.1016/0092-8674(82)90244-6. [DOI] [PubMed] [Google Scholar]
- Rundell K. Complete interaction of cellular 56,000- and 32,000-Mr proteins with simian virus 40 small-t antigen in productively infected cells. J Virol. 1987 Apr;61(4):1240–1243. doi: 10.1128/jvi.61.4.1240-1243.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheidtmann K. H., Buck M., Schneider J., Kalderon D., Fanning E., Smith A. E. Biochemical characterization of phosphorylation site mutants of simian virus 40 large T antigen: evidence for interaction between amino- and carboxy-terminal domains. J Virol. 1991 Mar;65(3):1479–1490. doi: 10.1128/jvi.65.3.1479-1490.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheidtmann K. H., Echle B., Walter G. Simian virus 40 large T antigen is phosphorylated at multiple sites clustered in two separate regions. J Virol. 1982 Oct;44(1):116–133. doi: 10.1128/jvi.44.1.116-133.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheidtmann K. H., Mumby M. C., Rundell K., Walter G. Dephosphorylation of simian virus 40 large-T antigen and p53 protein by protein phosphatase 2A: inhibition by small-t antigen. Mol Cell Biol. 1991 Apr;11(4):1996–2003. doi: 10.1128/mcb.11.4.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheidtmann K. H. Phosphorylation of simian virus 40 large T antigen: cytoplasmic and nuclear phophorylation sites differ in their metabolic stability. Virology. 1986 Apr 15;150(1):85–95. [PubMed] [Google Scholar]
- Scheidtmann K. H., Schickedanz J., Walter G., Lanford R. E., Butel J. S. Differential phosphorylation of cytoplasmic and nuclear variants of simian virus 40 large T antigen encoded by simian virus 40-adenovirus 7 hybrid viruses. J Virol. 1984 May;50(2):636–640. doi: 10.1128/jvi.50.2.636-640.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheidtmann K. H., Virshup D. M., Kelly T. J. Protein phosphatase 2A dephosphorylates simian virus 40 large T antigen specifically at residues involved in regulation of DNA-binding activity. J Virol. 1991 Apr;65(4):2098–2101. doi: 10.1128/jvi.65.4.2098-2101.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Seif R., Martin R. G. Growth state of the cell early after infection with simian virus 40 determines whether the maintenance of transformation will be A-gene dependent or independent. J Virol. 1979 Aug;31(2):350–359. doi: 10.1128/jvi.31.2.350-359.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shenk T. E., Carbon J., Berg P. Construction and analysis of viable deletion mutants of simian virus 40. J Virol. 1976 May;18(2):664–671. doi: 10.1128/jvi.18.2.664-671.1976. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sleigh M. J., Topp W. C., Hanich R., Sambrook J. F. Mutants of SV40 with an altered small t protein are reduced in their ability to transform cells. Cell. 1978 May;14(1):79–88. doi: 10.1016/0092-8674(78)90303-3. [DOI] [PubMed] [Google Scholar]
- Stürzbecher H. W., Montenarh M., Henning R. Enhanced protein phosphorylation in SV40-transformed and -infected cells. Virology. 1987 Oct;160(2):445–455. doi: 10.1016/0042-6822(87)90016-x. [DOI] [PubMed] [Google Scholar]
- Sugden B., Marsh K., Yates J. A vector that replicates as a plasmid and can be efficiently selected in B-lymphoblasts transformed by Epstein-Barr virus. Mol Cell Biol. 1985 Feb;5(2):410–413. doi: 10.1128/mcb.5.2.410. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Virshup D. M., Kauffman M. G., Kelly T. J. Activation of SV40 DNA replication in vitro by cellular protein phosphatase 2A. EMBO J. 1989 Dec 1;8(12):3891–3898. doi: 10.1002/j.1460-2075.1989.tb08568.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walser A., Deppert W. The kinase activity of SV40 large T antigen is mediated by a cellular kinase. EMBO J. 1986 May;5(5):883–889. doi: 10.1002/j.1460-2075.1986.tb04299.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walter G., Ruediger R., Slaughter C., Mumby M. Association of protein phosphatase 2A with polyoma virus medium tumor antigen. Proc Natl Acad Sci U S A. 1990 Apr;87(7):2521–2525. doi: 10.1073/pnas.87.7.2521. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wulf E., Deboben A., Bautz F. A., Faulstich H., Wieland T. Fluorescent phallotoxin, a tool for the visualization of cellular actin. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4498–4502. doi: 10.1073/pnas.76.9.4498. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yang S. I., Lickteig R. L., Estes R., Rundell K., Walter G., Mumby M. C. Control of protein phosphatase 2A by simian virus 40 small-t antigen. Mol Cell Biol. 1991 Apr;11(4):1988–1995. doi: 10.1128/mcb.11.4.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yang Y. C., Hearing P., Rundell K. Cellular proteins associated with simian virus 40 early gene products in newly infected cells. J Virol. 1979 Oct;32(1):147–154. doi: 10.1128/jvi.32.1.147-154.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zerrahn J., Deppert W., Weidemann D., Patschinsky T., Richards F., Milner J. Correlation between the conformational phenotype of p53 and its subcellular location. Oncogene. 1992 Jul;7(7):1371–1381. [PubMed] [Google Scholar]
- Zhu J. Y., Rice P. W., Chamberlain M., Cole C. N. Mapping the transcriptional transactivation function of simian virus 40 large T antigen. J Virol. 1991 Jun;65(6):2778–2790. doi: 10.1128/jvi.65.6.2778-2790.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]