Integration of the simian virus 40 genome into cellular DNA in temperature-sensitive (N) and temperature-insensitive (A) transformants of 3T3 rat and Chinese hamster lung cells

DNA fragments containing the integrated viral DNA present in the simian virus 40 (SV40)-transformed rat cell lines SVRE9 and SVRE17 were cloned in procaryotic vectors, and the DNA sequences linking SV40 and cell DNA were determined. Comparison of the DNA sequences at the SV40-cell junctions in SVRE9 and SVRE17 cells with those of a previously characterized viral insertion from SV14B cells shows that no specific viral or cellular sequences occur at SV40-cell junctions and that the cellular DNA sequences adjacent to integrated SV40 DNA do not display the direct repeat structure characteristic of transposons and retrovirus proviruses.

mentioning

confidence: 99%

Integrated Simian Virus 40 DNA: Nucleotide Sequences at Cell-Virus Recombinant Junctions

Stringer

1981

“…So far, most analyses on the arrangement of Py and simian virus 40 DNA in transformed cells indicated that integration is unspecific with respect to both viral and cellular DNA sequences (2,6,7,17,25,27,48). However, similar integration patterns have been found for some independently isolated rat cell lines transformed by simian virus 40 (8,34). The synthesis of the 61-kDal truncated IT and the specificity of integration observed in our study could be due to a particular nucleotide sequence, presumably located between 7 and 8.9 map units on the viral genome.…”

Section: Discussionmentioning

confidence: 83%

A 61,000-dalton truncated large T-antigen is uniformly expressed in hamster cells transformed by polyomavirus

Rey-Bellet¹,

Türler²

1984

Various polyomavirus-transformed hamster cell lines derived from tumors or from infected hamster cell cultures synthesized polyoma middle and small tumor (T)-antigens but no full-size large T-antigen. Instead, all cell lines produced the same or similar polyoma T-antigen-related proteins of ca. 61 kilodaltons (kDal). Like large T-antigen synthesized in lytically infected mouse cells, the 61-kDal proteins were phosphoproteins showing electrophoretic and charge heterogeneities. Chromatographic analysis of the methioninecontaining tryptic peptides indicated that the 61-kDal proteins were truncated forms of large T-antigen comprising amino acid residues 1 to 485 (±25). Analysis of viral DNA present in hamster chromosomal DNA of three independently isolated cell lines confirmed that synthesis of the 61-kDal proteins was due to a discontinuity in the large T-antigen coding sequence, most likely located between 7 and 8.9 map units on the polyoma DNA map. The three cell lines yielded essentially the same patterns of viral DNA-containing restriction enzyme fragments, suggesting that insertion of viral DNA into the hamster chromosomes took place at closely similar sites.

“…Fisher rat 3T3 cell lines that were transformed by a temperature-sensitive mutant of SV40, but that were temperature insensitive and that contained SV40 sequences at one (FR3T3 A12) or a few (FR3T3 A24 and FR3T3 A84) sites (3,9), were grown at the nonpermissive temperature, and flat revertants were selected. (No attempt was made to determine precisely the frequency of reversion, but calculating from the number of cells used and the number of flat revertants obtained, the frequency was roughly 1 in 107.…”

Section: Resultsmentioning

confidence: 99%

“…The cell lines and blotting techniques have been described previously (3,9), except that the partial acid hydrolysis procedure of Wahl et al (13) was added. The selection for flat revertants was carried out at 40°C precisely as described by Steinberg et al (11).…”

Section: Methodsmentioning

confidence: 99%

Flat revertants of temperature-insensitive transformants induced by simian virus 40 tsA mutants lose their ability to express T-antigen

Chepelinsky¹,

Chiu²,

Zannis‐Hadjopoulos³

et al. 1983

Self Cite

Temperature-insensitive transformants that contained simian virus 40 sequences at only one or a few sites in the rat chromosome and that were induced by a temperature-sensitive A gene mutant of simian virus 40 were used to select flat revertants (revertants that had lost the transformed phenotype). The isolation was performed at the nonpermissive temperature so as not to select against temperature-sensitive transformants. Nonetheless, all of the revertants examined had lost their ability to express the T-antigen at both temperatures, and all contained rearrangements of the integrated simian virus 40 sequences. These results are most compatible with the hypothesis that the T-antigen of simian virus 40 is required for the maintenance of the transformed state even in temperature-insensitive cell lines.