scholarly journals Stabilization of the 53,000-dalton nonviral tumor antigen is not required for transformation by simian virus 40.

1983 ◽  
Vol 3 (2) ◽  
pp. 290-296 ◽  
Author(s):  
L M Sompayrac ◽  
E G Gurney ◽  
K J Danna
Keyword(s):  
Cell Lines ◽  
Tumor Antigen ◽  
Deletion Mutant ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
Coding Region ◽  
Present Evidence ◽  
Mouse Cells

We have isolated a simian virus 40 deletion mutant, F8dl, that lacks the sequences from 0.168 to 0.424 map units. The deleted sequences represent about one-half of the coding region for large T antigen. We present evidence here that F8dl is able to transform mouse cells in a focus assay and that cell lines derived from these foci exhibit fully transformed phenotypes, have integrated mutant genomes, and express mutant-encoded proteins. This result implies that the region of the simian virus 40 genome between 0.168 and 0.424 map units is not essential for the maintenance of transformation. In addition, we have found that cells fully transformed by F8dl produce a 53,000-dalton nonviral tumor antigen (p53) that is as unstable as the p53 of untransformed cells. From this result we infer that transformation by simian virus 40 does not require the stabilization of p53.

Stabilization of the 53,000-dalton nonviral tumor antigen is not required for transformation by simian virus 40

1983 ◽  
Vol 3 (2) ◽  
pp. 290-296
Author(s):  
L M Sompayrac ◽  
E G Gurney ◽  
K J Danna
Keyword(s):  
Cell Lines ◽  
Tumor Antigen ◽  
Deletion Mutant ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
Coding Region ◽  
Present Evidence ◽  
Mouse Cells

We have isolated a simian virus 40 deletion mutant, F8dl, that lacks the sequences from 0.168 to 0.424 map units. The deleted sequences represent about one-half of the coding region for large T antigen. We present evidence here that F8dl is able to transform mouse cells in a focus assay and that cell lines derived from these foci exhibit fully transformed phenotypes, have integrated mutant genomes, and express mutant-encoded proteins. This result implies that the region of the simian virus 40 genome between 0.168 and 0.424 map units is not essential for the maintenance of transformation. In addition, we have found that cells fully transformed by F8dl produce a 53,000-dalton nonviral tumor antigen (p53) that is as unstable as the p53 of untransformed cells. From this result we infer that transformation by simian virus 40 does not require the stabilization of p53.

scholarly journals New Insights into the Mechanism of Inhibition of p53 by Simian Virus 40 Large T Antigen

1999 ◽  
Vol 19 (4) ◽  
pp. 2746-2753 ◽  
Author(s):  
Hilary M. Sheppard ◽  
Siska I. Corneillie ◽  
Christine Espiritu ◽  
Andrea Gatti ◽  
Xuan Liu
Keyword(s):  
Tumor Antigen ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Human Cells ◽  
Transactivation Domain ◽  
Large T Antigen ◽  
Large Tumor ◽  
Mechanism Of Inhibition ◽  
Mouse Cells

ABSTRACT Simian virus 40 (SV40) large tumor antigen (T antigen) has been shown to inhibit p53-dependent transcription by preventing p53 from binding to its cognate cis element. Data presented in this report provide the first direct functional evidence that T antigen, under certain conditions, may also repress p53-dependent transcription by a mechanism in which the transactivation domain of p53 is abrogated while DNA binding is unaffected. Specifically, p53 purified as a complex with T antigen from mouse cells was found to bind DNA as a transcriptionally inactive intact complex, while that purified from human cells was found to bind DNA independently of T antigen and could activate p53-dependent transcription. This difference in activity may be dependent on a different interaction of T antigen with mouse and human p53 and, in addition, on the presence of super T, which is found only in transformed rodent cells. These results suggest that subtle yet important differences exist between the inhibition of p53 by T antigen in mouse and human cells. The implications of this finding with respect to SV40-associated malignancies are discussed.

Less than 40% of the simian virus 40 large T-antigen-coding sequence is required for transformation

1984 ◽  
Vol 4 (8) ◽  
pp. 1661-1663
Author(s):  
L Sompayrac ◽  
K J Danna
Keyword(s):  
Dna Sequences ◽  
Deletion Mutant ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Large Deletion ◽  
T Antigen ◽  
Large T Antigen ◽  
Wild Type ◽  
Coding Sequence ◽  
Mouse Cells

F8dl is a simian virus 40 early-region deletion mutant that lacks the simian virus 40 DNA sequences between 0.168 and 0.424 map units. Despite this large deletion, cloned F8dl DNA transforms Fisher rat F111 cells and BALB/3T3 clone A31 mouse cells as efficiently as does cloned simian virus 40 wild-type DNA. These results indicate that less than 40% of the large T-antigen-coding sequence is required for efficient transformation.

scholarly journals Less than 40% of the simian virus 40 large T-antigen-coding sequence is required for transformation.

1984 ◽  
Vol 4 (8) ◽  
pp. 1661-1663 ◽  
Author(s):  
L Sompayrac ◽  
K J Danna
Keyword(s):  
Dna Sequences ◽  
Deletion Mutant ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Large Deletion ◽  
T Antigen ◽  
Large T Antigen ◽  
Wild Type ◽  
Coding Sequence ◽  
Mouse Cells

F8dl is a simian virus 40 early-region deletion mutant that lacks the simian virus 40 DNA sequences between 0.168 and 0.424 map units. Despite this large deletion, cloned F8dl DNA transforms Fisher rat F111 cells and BALB/3T3 clone A31 mouse cells as efficiently as does cloned simian virus 40 wild-type DNA. These results indicate that less than 40% of the large T-antigen-coding sequence is required for efficient transformation.

Recombinant retroviruses encoding simian virus 40 large T antigen and polyomavirus large and middle T antigens

1986 ◽  
Vol 6 (4) ◽  
pp. 1204-1217
Author(s):  
P S Jat ◽  
C L Cepko ◽  
R C Mulligan ◽  
P A Sharp
Keyword(s):  
Cell Lines ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Vector System ◽  
Large T Antigen ◽  
T Antigens ◽  
Sv40 Large T Antigen ◽  
Polyomavirus Middle T Antigen ◽  
Middle T Antigen

We used a murine retrovirus shuttle vector system to construct recombinants capable of constitutively expressing the simian virus 40 (SV40) large T antigen and the polyomavirus large and middle T antigens as well as resistance to G418. Subsequently, these recombinants were used to generate cell lines that produced defective helper-free retroviruses carrying each of the viral oncogenes. These recombinant retroviruses were used to analyze the role of the viral genes in transformation of rat F111 cells. Expression of the polyomavirus middle T antigen alone resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were unaltered by the criteria of morphology, anchorage-independent growth, and tumorigenicity. More surprisingly, SV40 large T-expressing cell lines were not tumorigenic despite the fact that they contained elevated levels of cellular p53 and had a high plating efficiency in soft agar. These results suggest that the SV40 large T antigen is not an acute transforming gene like the polyomavirus middle T antigen but is similar to the establishment genes such as myc and adenovirus EIa.

scholarly journals Growth of immortal simian virus 40 tsA-transformed human fibroblasts is temperature dependent.

1989 ◽  
Vol 9 (7) ◽  
pp. 3093-3096 ◽  
Author(s):  
R L Radna ◽  
Y Caton ◽  
K K Jha ◽  
P Kaplan ◽  
G Li ◽  
...  
Keyword(s):  
Cell Lines ◽  
Human Fibroblasts ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Cellular Aging ◽  
Cellular Growth ◽  
Viral Gene ◽  
Large T Antigen ◽  
Temperature Dependent

Simian virus 40 (SV40)-mediated transformation of human fibroblasts offers an experimental system for studying both carcinogenesis and cellular aging, since such transformants show the typical features of altered cellular growth but still have a limited life span in culture and undergo senescence. We have previously demonstrated (D. S. Neufeld, S. Ripley, A. Henderson, and H. L. Ozer, Mol. Cell. Biol. 7:2794-2802, 1987) that transformants generated with origin-defective mutants of SV40 show an increased frequency of overcoming senescence and becoming immortal. To clarify further the role of large T antigen, we have generated immortalized transformants by using origin-defective mutants of SV40 encoding a heat-labile large T antigen (tsA58 transformants). At a temperature permissive for large-T-antigen function (35 degrees C), the cell line AR5 had properties resembling those of cell lines transformed with wild-type SV40. However, the AR5 cells were unable to proliferate or form colonies at temperatures restrictive for large-T-antigen function (39 degrees C), demonstrating a continuous need for large T antigen even in immortalized human fibroblasts. Such immortal temperature-dependent transformants should be useful cell lines for the identification of other cellular or viral gene products that induce cell proliferation in human cells.

scholarly journals Recombinant retroviruses encoding simian virus 40 large T antigen and polyomavirus large and middle T antigens.

1986 ◽  
Vol 6 (4) ◽  
pp. 1204-1217 ◽  
Author(s):  
P S Jat ◽  
C L Cepko ◽  
R C Mulligan ◽  
P A Sharp
Keyword(s):  
Cell Lines ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Vector System ◽  
Large T Antigen ◽  
T Antigens ◽  
Sv40 Large T Antigen ◽  
Polyomavirus Middle T Antigen ◽  
Middle T Antigen

We used a murine retrovirus shuttle vector system to construct recombinants capable of constitutively expressing the simian virus 40 (SV40) large T antigen and the polyomavirus large and middle T antigens as well as resistance to G418. Subsequently, these recombinants were used to generate cell lines that produced defective helper-free retroviruses carrying each of the viral oncogenes. These recombinant retroviruses were used to analyze the role of the viral genes in transformation of rat F111 cells. Expression of the polyomavirus middle T antigen alone resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were unaltered by the criteria of morphology, anchorage-independent growth, and tumorigenicity. More surprisingly, SV40 large T-expressing cell lines were not tumorigenic despite the fact that they contained elevated levels of cellular p53 and had a high plating efficiency in soft agar. These results suggest that the SV40 large T antigen is not an acute transforming gene like the polyomavirus middle T antigen but is similar to the establishment genes such as myc and adenovirus EIa.

scholarly journals Cell-Specific Modulation of Papovavirus Replication by Tumor Suppressor Protein p53

2000 ◽  
Vol 74 (10) ◽  
pp. 4688-4697 ◽  
Author(s):  
Dina Lepik ◽  
Mart Ustav
Keyword(s):  
Tumor Suppressor ◽  
Cell Lines ◽  
P53 Protein ◽  
Chinese Hamster ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
S Phase ◽  
Human Papillomaviruses ◽  
Mouse Cells

ABSTRACT Small DNA tumor viruses like human papillomaviruses, simian virus 40, and adenoviruses modulate the activity of cellular tumor suppressor proteins p53 and/or pRB. These viruses replicate as nuclear multicopy extrachromosomal elements during the S phase of the cell cycle, and it has been suggested that inactivation of p53 and pRb is necessary for directing the cells to the S phase. Mouse polyomavirus (Py), however, modulates only the pRB protein activity without any obvious interference with the action of p53. We show here that Py replication was not suppressed by the p53 protein indeed in all tested different mouse cell lines. In addition, E1- and E2-dependent papillomavirus origin replication was insensitive to the action of p53 in mouse cells. We show that in hamster (Chinese hamster ovary) or human (osteosarcoma 143) cell lines the replication of both Py and papillomavirus origins was efficiently blocked by p53. The block of Py replication in human and hamster cells is not caused by the downregulation of large T-antigen expression. The deletion analysis of the p53 protein shows that the RPA binding, proline-rich regulatory, DNA-binding, and oligomerization domains are necessary for p53 action in both replication systems. These results indicate that in mouse cells the p53 protein could be inactive for the suppression of papovavirus replication.

Sign in / Sign up

Export Citation Format

Share Document