Differential sensitivity to aphidicolin of replicative DNA synthesis and ultraviolet-induced unscheduled DNA synthesis in vivo in mammalian cells.
In vivo in mammalian cells, ultraviolet-induced unscheduled DNA synthesis was less sensitive to aphidicolin than was replicative DNA synthesis. Replicative DNA synthesis in HeLa, HEp-2, WI-38 VA-13 and CV-1 cells was inhibited more than 97% by aphidicolin at 10 micrograms/ml, whereas aphidicolin inhibition of DNA synthesis in ultraviolet-irradiated cells varied between 30% and 90% depending on cell types and assay conditions. Aphidicolin inhibition of unscheduled DNA synthesis (UDS) in HeLa cells increased gradually with increasing aphidicolin concentration and reached approximately 90% at 100 micrograms/ml aphidicolin. A significant fraction of UDS in ultraviolet-irradiated HEp-2 cells was resistant to aphidicolin even at 300 micrograms/ml. Considered along with related information reported previously, the present results suggest that both aphidicolin-sensitive and insensitive DNA polymerases, DNA polymerase alpha and a non-alpha DNA polymerase (possibly DNA polymerase beta), are involved in in situ UDS in these ultraviolet-irradiated cells. Comparison of staphylococcal nuclease sensitivity between DNAs repaired in the presence and in the absence of aphidicolin in HEp-2 cells suggested that the involvement of DNA polymerase alpha in UDS favored DNA synthesis in the intranucleosomal region.
D000818:Animals; D016590:Aphidicolin; D004247:DNA / Q000096:biosynthesis / Q000528:radiation effects*; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004224:Diterpenes / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006367:HeLa Cells; D006801:Humans; D008836:Micrococcal Nuclease / Q000378:metabolism; D014466:Ultraviolet Rays
D004224:Diterpenes; D016590:Aphidicolin; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D008836:Micrococcal Nuclease