Amplification of polyomavirus DNA sequences stably integrated in rat cells.
AUTOR(ES)
St-Onge, L
RESUMO
To investigate the mechanism by which the polyomavirus large T antigen (T-Ag) promotes amplification of integrated viral sequences, we constructed a rat cell line, Hy2-ts5, carrying two different inserts of polyomavirus DNA. The first insert, designated the middle T (pmt) locus, was devised to analyze homologous recombination between two defective copies of pmt lying 3.3 kb apart on the same chromosome. Reconstitution of a functional pmt by spontaneous recombination occurred at a rate of about 2 x 10(-7) per cell generation. The second locus contained the polyomavirus large T (plt) gene carrying a temperature-sensitive mutation and producing a nonfunctional large T-Ag at 39 degrees C. A shift to the permissive temperature for as little as 24 h induced the production of a functional large T-Ag which, in turn, promoted homologous recombination in the pmt locus at a rate close to 1.0 per cell generation. The particularity of this system is that it allowed recombination products to be analyzed as early as a single cell doubling following the initial recombinational event. Amplification occurred by successive duplications of a discrete sequence in the viral insert. Unequal sister chromatid exchange was ruled out as the recombination mechanism promoted by large T-Ag. Instead, we proposed a model of nonconservative recombination involving mispairing between homologous sequences.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=329231Documentos Relacionados
- Amplification of integrated viral DNA sequences in polyoma virus-transformed cells.
- Patterns of methylation of polyomavirus DNA in polyoma-transformed rat cells.
- Unequal homologous recombination between tandemly arranged sequences stably incorporated into cultured rat cells.
- Amplification of DNA sequences in human multidrug-resistant KB carcinoma cells.
- Structural and biological analysis of integrated polyoma virus DNA and its adjacent host sequences cloned from transformed rat cells.