scholarly journals Simian virus 40 large-T antigen expresses a biological activity complementary to the p300-associated transforming function of the adenovirus E1A gene products.

1991 ◽  
Vol 11 (4) ◽  
pp. 2116-2124 ◽  
Author(s):  
P Yaciuk ◽  
M C Carter ◽  
J M Pipas ◽  
E Moran
Keyword(s):  
Biological Activity ◽  
Rat Kidney ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Binding Region ◽  
Adenovirus E1a ◽  
P300 Binding ◽  
Transforming Activity ◽  
E1a Gene

In this report we present evidence that simian virus 40 T antigen encodes a biological activity that is functionally equivalent to the transforming activity lost by deletion of the E1A p300-binding region. T-antigen constructs from which the pRb-binding region has been deleted are virtually unable to induce foci of transformed cells in a ras cooperation assay in primary baby rat kidney cells. Nevertheless, such a construct can cooperate with an E1A N-terminal deletion mutant, itself devoid of transforming activity, to induce foci in this assay. The heterologous trans-cooperating activity observed between E1A and T-antigen deletion products is as efficient as trans cooperation between mutants expressing individual E1A domains. The cooperating function can be impaired by a deletion near the N terminus of T antigen. Such a deletion impairs neither the p53-binding function nor the activity of the pRb-binding region.

Simian virus 40 large-T antigen expresses a biological activity complementary to the p300-associated transforming function of the adenovirus E1A gene products

1991 ◽  
Vol 11 (4) ◽  
pp. 2116-2124
Author(s):  
P Yaciuk ◽  
M C Carter ◽  
J M Pipas ◽  
E Moran
Keyword(s):  
Biological Activity ◽  
Rat Kidney ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Binding Region ◽  
Adenovirus E1a ◽  
P300 Binding ◽  
Transforming Activity ◽  
E1a Gene

In this report we present evidence that simian virus 40 T antigen encodes a biological activity that is functionally equivalent to the transforming activity lost by deletion of the E1A p300-binding region. T-antigen constructs from which the pRb-binding region has been deleted are virtually unable to induce foci of transformed cells in a ras cooperation assay in primary baby rat kidney cells. Nevertheless, such a construct can cooperate with an E1A N-terminal deletion mutant, itself devoid of transforming activity, to induce foci in this assay. The heterologous trans-cooperating activity observed between E1A and T-antigen deletion products is as efficient as trans cooperation between mutants expressing individual E1A domains. The cooperating function can be impaired by a deletion near the N terminus of T antigen. Such a deletion impairs neither the p53-binding function nor the activity of the pRb-binding region.

Stimulation of the adenovirus E2 promoter by simian virus 40 T antigen or E1A occurs by different mechanisms

1986 ◽  
Vol 6 (6) ◽  
pp. 2020-2026
Author(s):  
M R Loeken ◽  
G Khoury ◽  
J Brady
Keyword(s):  
Simian Virus 40 ◽  
Promoter Sequence ◽  
Simian Virus ◽  
Chloramphenicol Acetyltransferase ◽  
T Antigen ◽  
Base Pairs ◽  
Promoter Sequences ◽  
Adenovirus E1a ◽  
E1a Gene ◽  
Stimulation Of

We have examined the ability of simian virus 40 T antigen to stimulate transcription from the adenovirus E2 promoter. T antigen, produced from a cotransfected plasmid, stimulated chloramphenicol acetyltransferase enzyme and mRNA production from an E2 promoter-chloramphenicol acetyltransferase fusion plasmid (pEC113) in monkey kidney CV-1 cells. The level of stimulation of E2 transcription by simian virus 40 T antigen was equal to that observed in cotransfections of pEC113 and the adenovirus E1A gene product. Deletion mutations from the 5' end of the E2 promoter were examined for their ability to express basal, T-antigen, or E1A trans-activated promoter activity. In each case, deletion of upstream promoter sequences to -70 base pairs reduced chloramphenicol acetyltransferase expression to approximately 30% of the level observed with the intact E2 promoter. Deletion to -59 base pairs resulted in chloramphenicol acetyltransferase expression that was 3 to 5% of that observed with the intact E2 promoter. At saturating levels of the stimulatory proteins, the chloramphenicol acetyltransferase levels obtained in response to T antigen and adenovirus E1A were additive. COS-1 cells, which are derived from CV-1 cells and constitutively express simian virus 40 T antigen, do not support E2 promoter trans activation by T antigen. E1A trans activation of the E2 promoter is efficient in COS-1 cells. These results suggest that although promoter sequence requirements are similar, T antigen and E1A trans activate the E2 promoter by different mechanisms.

scholarly journals Tumorigenicity of fibroblast lines expressing the adenovirus E1a, cellular p53, or normal c-myc genes.

1986 ◽  
Vol 6 (1) ◽  
pp. 7-14 ◽  
Author(s):  
A Kelekar ◽  
M D Cole
Keyword(s):  
Simian Virus 40 ◽  
Adenovirus Type ◽  
Simian Virus ◽  
Primary Cells ◽  
Adenovirus E1a ◽  
Immortalized Cells ◽  
Transforming Activity ◽  
E1a Gene

Cellular and viral oncogenes have been linked to the transformation of established cell lines in vitro, to the induction of tumors in vivo, and to the partial transformation or immortalization of primary cells. Based on the ability to cooperate with mutated ras oncogenes in the transformation of primary cells, the adenovirus E1a and cellular p53 genes have been assigned an immortalizing activity. It is demonstrated in this paper that the adenovirus type 5 E1a gene and simian virus 40 promoter-linked p53 cDNA are able to transform previously immortalized cells to a tumorigenic phenotype without a significant change in cell morphology. It is also shown that, when linked to a constitutive promoter, the normal mouse and human c-myc genes have the same transforming activity. Cells transformed by each of these oncogenes have an increased capacity to grow in the absence of growth factors and a limited anchorage-independent growth capability.

scholarly journals Stimulation of the adenovirus E2 promoter by simian virus 40 T antigen or E1A occurs by different mechanisms.

1986 ◽  
Vol 6 (6) ◽  
pp. 2020-2026 ◽  
Author(s):  
M R Loeken ◽  
G Khoury ◽  
J Brady
Keyword(s):  
Simian Virus 40 ◽  
Promoter Sequence ◽  
Simian Virus ◽  
Chloramphenicol Acetyltransferase ◽  
T Antigen ◽  
Base Pairs ◽  
Promoter Sequences ◽  
Adenovirus E1a ◽  
E1a Gene ◽  
Stimulation Of

We have examined the ability of simian virus 40 T antigen to stimulate transcription from the adenovirus E2 promoter. T antigen, produced from a cotransfected plasmid, stimulated chloramphenicol acetyltransferase enzyme and mRNA production from an E2 promoter-chloramphenicol acetyltransferase fusion plasmid (pEC113) in monkey kidney CV-1 cells. The level of stimulation of E2 transcription by simian virus 40 T antigen was equal to that observed in cotransfections of pEC113 and the adenovirus E1A gene product. Deletion mutations from the 5' end of the E2 promoter were examined for their ability to express basal, T-antigen, or E1A trans-activated promoter activity. In each case, deletion of upstream promoter sequences to -70 base pairs reduced chloramphenicol acetyltransferase expression to approximately 30% of the level observed with the intact E2 promoter. Deletion to -59 base pairs resulted in chloramphenicol acetyltransferase expression that was 3 to 5% of that observed with the intact E2 promoter. At saturating levels of the stimulatory proteins, the chloramphenicol acetyltransferase levels obtained in response to T antigen and adenovirus E1A were additive. COS-1 cells, which are derived from CV-1 cells and constitutively express simian virus 40 T antigen, do not support E2 promoter trans activation by T antigen. E1A trans activation of the E2 promoter is efficient in COS-1 cells. These results suggest that although promoter sequence requirements are similar, T antigen and E1A trans activate the E2 promoter by different mechanisms.

Tumorigenicity of fibroblast lines expressing the adenovirus E1a, cellular p53, or normal c-myc genes

1986 ◽  
Vol 6 (1) ◽  
pp. 7-14
Author(s):  
A Kelekar ◽  
M D Cole
Keyword(s):  
Simian Virus 40 ◽  
Adenovirus Type ◽  
Simian Virus ◽  
Primary Cells ◽  
Adenovirus E1a ◽  
Immortalized Cells ◽  
Transforming Activity ◽  
E1a Gene

Cellular and viral oncogenes have been linked to the transformation of established cell lines in vitro, to the induction of tumors in vivo, and to the partial transformation or immortalization of primary cells. Based on the ability to cooperate with mutated ras oncogenes in the transformation of primary cells, the adenovirus E1a and cellular p53 genes have been assigned an immortalizing activity. It is demonstrated in this paper that the adenovirus type 5 E1a gene and simian virus 40 promoter-linked p53 cDNA are able to transform previously immortalized cells to a tumorigenic phenotype without a significant change in cell morphology. It is also shown that, when linked to a constitutive promoter, the normal mouse and human c-myc genes have the same transforming activity. Cells transformed by each of these oncogenes have an increased capacity to grow in the absence of growth factors and a limited anchorage-independent growth capability.

Maintenance of cellular proliferation by adenovirus early region 1A in fibroblasts conditionally immortalized by using simian virus 40 large T antigen requires conserved region 1

1990 ◽  
Vol 10 (12) ◽  
pp. 6664-6673
Author(s):  
T E Riley ◽  
A Follin ◽  
N C Jones ◽  
P S Jat
Keyword(s):  
Cell Line ◽  
Growth Arrest ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Growth Defect ◽  
Primary Cells ◽  
Nonpermissive Temperature ◽  
Large T Antigen ◽  
Adenovirus E1a

Various mutants of adenovirus E1A were assayed for their ability to complement the growth defect at the nonpermissive temperature for the cell line tsa14 which was isolated by immortalizing rat embryo fibroblasts with the thermolabile large T antigen of tsA58. This cell line grows indefinitely at the permissive temperature but undergoes rapid growth arrest upon shift up to the nonpermissive temperature. Since this growth arrest can be overcome by introduction of wild-type simian virus 40 large T antigen, human papillomavirus 16 E7, and adenovirus E1A, the tsa14 cells provided an excellent system for defining regions of E1A necessary for complementation of the growth defect. We demonstrate that conserved region 1 (CR1) is the region of E1A required for complementation. While CR2 of E1A has been shown to be required for the immortalization of primary cells and is also necessary for the binding of the 105-kDa retinoblastoma protein, mutations within this region did not abrogate complementation of the growth defect. However, since both CR1 and CR2 have previously been shown to be absolutely required for immortalization of primary cells by adenovirus E1A, this evidence suggests that the tsa14 system assays for the maintenance of proliferation and that this requires CR1.

scholarly journals Maintenance of cellular proliferation by adenovirus early region 1A in fibroblasts conditionally immortalized by using simian virus 40 large T antigen requires conserved region 1.

1990 ◽  
Vol 10 (12) ◽  
pp. 6664-6673 ◽  
Author(s):  
T E Riley ◽  
A Follin ◽  
N C Jones ◽  
P S Jat
Keyword(s):  
Cell Line ◽  
Growth Arrest ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Growth Defect ◽  
Primary Cells ◽  
Nonpermissive Temperature ◽  
Large T Antigen ◽  
Adenovirus E1a

Various mutants of adenovirus E1A were assayed for their ability to complement the growth defect at the nonpermissive temperature for the cell line tsa14 which was isolated by immortalizing rat embryo fibroblasts with the thermolabile large T antigen of tsA58. This cell line grows indefinitely at the permissive temperature but undergoes rapid growth arrest upon shift up to the nonpermissive temperature. Since this growth arrest can be overcome by introduction of wild-type simian virus 40 large T antigen, human papillomavirus 16 E7, and adenovirus E1A, the tsa14 cells provided an excellent system for defining regions of E1A necessary for complementation of the growth defect. We demonstrate that conserved region 1 (CR1) is the region of E1A required for complementation. While CR2 of E1A has been shown to be required for the immortalization of primary cells and is also necessary for the binding of the 105-kDa retinoblastoma protein, mutations within this region did not abrogate complementation of the growth defect. However, since both CR1 and CR2 have previously been shown to be absolutely required for immortalization of primary cells by adenovirus E1A, this evidence suggests that the tsa14 system assays for the maintenance of proliferation and that this requires CR1.

scholarly journals Induction versus progression of brain tumor development: differential functions for the pRB- and p53-targeting domains of simian virus 40 T antigen.

1994 ◽  
Vol 14 (4) ◽  
pp. 2686-2698 ◽  
Author(s):  
M T Sáenz Robles ◽  
H Symonds ◽  
J Chen ◽  
T Van Dyke
Keyword(s):  
Tumor Progression ◽  
Choroid Plexus ◽  
Simian Virus 40 ◽  
Cell Types ◽  
Simian Virus ◽  
T Antigen ◽  
Cellular Proteins ◽  
Wild Type ◽  
Binding Region ◽  
Amino Terminal

The ability of simian virus 40-encoded large T antigen to disrupt the growth control of a variety of cell types is related to its ability to interfere with certain cellular proteins, such as p53 and the retinoblastoma susceptibility gene product (pRB). We have used wild-type and mutant forms of T antigen in transgenic mice to dissect the roles of pRB, p53, and other cellular proteins in tumorigenesis of different cell types. In this study, using a cell-specific promoter to target expression specifically to brain epithelium (the choroid plexus) and to B and T lymphoid cells, we characterize the tumorigenic capacity of a T-antigen fragment that comprises only the amino-terminal 121 residues. This fragment (dl1137) retains the ability to interact with pRB and p107 but lacks the p53-binding domain. While loss of the p53-binding region results in loss of the capacity to induce lymphoid abnormalities, dl1137 retains the ability to induce choroid plexus tumors that are histologically indistinguishable from those induced by wild-type T antigen. Tumors induced by dl1137 develop much more slowly, however, reaching an end point at around 8 months of age rather than at 1 to 2 months. Analysis of tumor progression indicates that tumor induction by dl1137 does not require secondary genetic or epigenetic events. Rather, the tumor growth rate is significantly slowed, indicating that the T-antigen C-terminal region contributes to tumor progression in this cell type. In contrast, the pRB-binding region appears essential for tumorigenesis as mutation of residue 107, known to disrupt pRB and p107 binding to wild-type T antigen, abolishes the ability of the dl1137 protein to induce growth abnormalities in the brain.

The adenovirus Ela gene induces differentiation of F9 teratocarcinoma cells

1987 ◽  
Vol 7 (5) ◽  
pp. 1782-1790
Author(s):  
X Montano ◽  
D P Lane
Keyword(s):  
Tumor Antigens ◽  
Morphological Changes ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Stem Cell Marker ◽  
Phenotypic Change ◽  
F9 Cells ◽  
Adenovirus E1a ◽  
E1a Gene ◽  
Marker Antigen

Undifferentiated F9 cells transfected with plasmids encoding adenovirus E1a gene products underwent radical morphological changes. They ceased to express the SSEA-1 stem cell marker antigen and started to express a number of the characteristics of the differentiated state that is induced in F9 cells by treatment with retinoic acid. In particular, they expressed keratin intermediate filaments and acquired the ability to synthesise simian virus 40 tumor antigens after virus infection. The transfected cells expressed the E1a proteins, and this expression was necessary to induce the phenotypic changes, since a coisogenic plasmid encoding only a truncated 70-amino-acid E1a polypeptide and the transfection procedure itself did not detectably after the morphology or marker expression of the F9 stem cells. The phenotypic change was induced by both 13S and 12S cDNA plasmids. We discuss these results in the context of known E1a functions and with reference to the other oncogenes and external factors that can cause F9 cell differentiation.

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