Repair of thymine dimers and (6-4) photoproducts in group A xeroderma pigmentosum cell lines harboring a transferred normal chromosome 9.
Transfer of a normal chromosome 9 into a xeroderma pigmentosum (XP)-A cell line partially restored its DNA repair activity. XP-A cell lines harboring a transferred chromosome were much more UV-resistant than parental XP-A cells but still more UV-sensitive than normal cells. The amount of UV-induced unscheduled DNA synthesis was only one-third of that in normal cells. The repair of thymine dimers and (6-4) photoproducts in these cell lines was analyzed by using monoclonal antibodies raised against them. Although these XP-A cell lines carrying a normal chromosome 9 could repair (6-4) photoproduct with a little lower efficiency than normal cells, the repair of thymine dimers was completely absent in these cells. The present results suggest a gene-dosage effect in DNA excision repair mechanisms in human cells or a rather complicated mechanism which involves two or more pathways.
Ishizaki
K
K
Radiation Biology Center, Kyoto University, Japan.
Matsunaga
T
T
Kato
M
M
Nikaido
O
O
Ikenaga
M
M
D002460:Cell Line; D002899:Chromosomes, Human, Pair 9; D004247:DNA / Q000235:genetics / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D006801:Humans; D011740:Pyrimidine Dimers; D014162:Transfection; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics*
D011740:Pyrimidine Dimers; D004247:DNA