scholarly journals Correlation of DNA content, p53, T antigen, and V antigen in simian virus 40-infected human diploid cells

Cytometry ◽  
1989 ◽  
Vol 10 (2) ◽  
pp. 205-213 ◽  
Author(s):  
Judith Laffin ◽  
David Fogleman ◽  
John M. Lehman
Keyword(s):  
Dna Content ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
V Antigen ◽  
Human Diploid Cells ◽  
Diploid Cells

Efficient transfer of cloned DNA into human diploid cells: protoplast fusion in suspension

1984 ◽  
Vol 4 (11) ◽  
pp. 2549-2552
Author(s):  
P Litzkas ◽  
K K Jha ◽  
H L Ozer
Keyword(s):  
Simian Virus 40 ◽  
Cell Types ◽  
Simian Virus ◽  
Selective Medium ◽  
T Antigen ◽  
Human Diploid Fibroblasts ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Human Diploid Cells ◽  
Diploid Cells

A method for fusion of protoplasts bearing amplified plasmids and human diploid fibroblasts or other cell types in suspension is described. Transient expression of plasmid-encoded proteins occurs in up to 50% of the human cells, as demonstrated for simian virus 40 T antigen by immunofluorescence and the Escherichia coli xanthine-guanine phosphoribosyl transferase by autoradiography. In contrast, frequencies of stable transformants were similar to those obtained by the CaPO4 coprecipitation technique. However, experiments with both methods involving the recombinant pRSVneo (in which the Rous sarcoma virus long terminal repeat regulates expression of the antibiotic-inactivating aminoglycoside phosphotransferase) revealed a much higher frequency of colonies in G418 selective medium with constructions in which the early region of simian virus 40 DNA was present as well. We propose a role for the simian virus 40 T antigen in enhancing stable transformation in this system.

scholarly journals Efficient transfer of cloned DNA into human diploid cells: protoplast fusion in suspension.

1984 ◽  
Vol 4 (11) ◽  
pp. 2549-2552 ◽  
Author(s):  
P Litzkas ◽  
K K Jha ◽  
H L Ozer
Keyword(s):  
Simian Virus 40 ◽  
Cell Types ◽  
Simian Virus ◽  
Selective Medium ◽  
T Antigen ◽  
Human Diploid Fibroblasts ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Human Diploid Cells ◽  
Diploid Cells

A method for fusion of protoplasts bearing amplified plasmids and human diploid fibroblasts or other cell types in suspension is described. Transient expression of plasmid-encoded proteins occurs in up to 50% of the human cells, as demonstrated for simian virus 40 T antigen by immunofluorescence and the Escherichia coli xanthine-guanine phosphoribosyl transferase by autoradiography. In contrast, frequencies of stable transformants were similar to those obtained by the CaPO4 coprecipitation technique. However, experiments with both methods involving the recombinant pRSVneo (in which the Rous sarcoma virus long terminal repeat regulates expression of the antibiotic-inactivating aminoglycoside phosphotransferase) revealed a much higher frequency of colonies in G418 selective medium with constructions in which the early region of simian virus 40 DNA was present as well. We propose a role for the simian virus 40 T antigen in enhancing stable transformation in this system.

scholarly journals Elevated recombination in immortal human cells is mediated by HsRAD51 recombinase.

1997 ◽  
Vol 17 (12) ◽  
pp. 7151-7158 ◽  
Author(s):  
S J Xia ◽  
M A Shammas ◽  
R J Shmookler Reis
Keyword(s):  
Cell Lines ◽  
Cell Transformation ◽  
Human Fibroblasts ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Cell Strains ◽  
Immortal Cells ◽  
Diploid Cells ◽  
Untransformed Cell

Normal diploid cells have a limited replicative potential in culture, with progressively increasing interdivision time. Rarely, cell lines arise which can divide indefinitely; like tumor cells, such "immortal" lines display frequent chromosomal aberrations which may reflect high rates of recombination. Recombination frequencies within a plasmid substrate were 3.5-fold higher in nine immortal human cell lines than in six untransformed cell strains. Expression of HsRAD51, a human homolog of the yeast RAD51 and Escherichia coli recA recombinase genes, was 4.5-fold higher in immortal cell lines than in mortal cells. Stable transformation of human fibroblasts with simian virus 40 large T antigen prior to cell immortalization increased both chromosomal recombination and the level of HsRAD51 transcripts by two- to fivefold. T-antigen induction of recombination was efficiently blocked by introduction of HsRAD51 antisense (but not control) oligonucleotides spanning the initiation codon, implying that HsRAD51 expression mediates augmented recombination. Since p53 binds and inactivates HsRAD51, T-antigen-p53 association may block such inactivation and liberate HsRAD51. Upregulation of HsRAD51 transcripts in T-antigen-transformed and other immortal cells suggests that recombinase activation can also occur at the RNA level and may facilitate cell transformation to immortality.

Reinitiation of host DNA synthesis in senescent human diploid cells by infection with simian virus 40

1983 ◽  
Vol 143 (2) ◽  
pp. 343-349 ◽  
Author(s):  
Toshinori Ide ◽  
Yoshiaki Tsuji ◽  
Sadahiko Ishibashi ◽  
Youji Mitsui
Keyword(s):  
Dna Synthesis ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Human Diploid Cells ◽  
Diploid Cells

Progress of aging in human diploid cells transformed with a tsA mutant of simian virus 40

1984 ◽  
Vol 150 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Toshinori Ide ◽  
Yoshiaki Tsuji ◽  
Tsuyoshi Nakashima ◽  
Sadahiko Ishibashi
Keyword(s):  
Simian Virus 40 ◽  
Simian Virus ◽  
Human Diploid Cells ◽  
Diploid Cells

scholarly journals Quantitative correlation between simian virus 40 T-antigen synthesis and late viral gene expression in permissive and nonpermissive cells

1978 ◽  
Vol 77 (1) ◽  
pp. R1 ◽  
Author(s):  
A Graessmann ◽  
M Graessmann ◽  
E Guhl ◽  
C Mueller
Keyword(s):  
Time Course ◽  
Viral Gene Expression ◽  
Simian Virus 40 ◽  
Threshold Value ◽  
Simian Virus ◽  
T Antigen ◽  
Threshold Concentration ◽  
Viral Gene ◽  
3T3 Cells ◽  
V Antigen

The time-course of intranuclear Simian virus 40 (SV40) tumor (T) antigen synthesis and accumulation in permissive CV1 monkey cells and nonpermissive 3T3 mouse cells has been studied by immunofluorescence and cytofluorometry. CV1 cells accumulate T antigen continuously over a period of 48 h after infection, whereas in 3T3 cells the T-antigen content remains about constant and at a comparatively low level. Only those CV1 cells which have attained a threshold concentration of intranuclear T antigen synthesize viral capsid proteins (V antigen). In nonpermissive 3T3 cells, the T-antigen threshold value for the onset of V-antigen synthesis is higher than in CV1 cells and is never reached by infected cells. However, 3T3 cells microinjected with sufficient amounts of SV40 DNA easily surpass this value and behave permissively.

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