Characterization of homologous DNA recombination activity in normal and immortal mammalian cells.
AUTOR(ES)
Thyagarajan, B
RESUMO
Homologous DNA recombination levels were measured in normal and spontaneously immortalized murine and human fibroblasts, and in a number of primate and murine established fibroblast cell lines. Immortal cell lines and tumor-derived clones homologously recombined extrachromosomal plasmid substrates at frequencies approximately 100-fold higher than did normal cells. To further explore the mechanism responsible for this phenotype, homologous recombination frequency was measured using nuclear extracts derived from normal and immortalized murine and human fibroblasts. Extracts prepared from immortal cells catalyzed high levels of homologous recombination, whereas very little recombination activity was detected in extracts prepared from normal fibroblasts. Similarly, only extracts derived from immortal cells contained strand-transferase activity as measured by the recently described pairing-on-membrane assay. Mixing experiments indicated that a recombination enhancing factor or factors present in immortal cells, rather than a recombination inhibitor in normal cells, was responsible for the enhanced homologous recombination activity observed using extracts derived from the former.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=146187Documentos Relacionados
- Transcription stimulates homologous recombination in mammalian cells.
- Transcription enhances intrachromosomal homologous recombination in mammalian cells.
- Requirements for ectopic homologous recombination in mammalian somatic cells.
- Topological requirements for homologous recombination among DNA molecules transfected into mammalian cells.
- Characterization of nonconservative homologous junctions in mammalian cells.