To verify the genetic instability of p53-deficient cells, UV-induced mutation of the supF gene on a shuttle vector was analyzed. UV-irradiated or non-irradiated shuttle vector plasmid carrying the supF gene as a target of mutation (pYZ289) was introduced into p53-deficient and p53-proficient mouse embryonic fibroblasts, and then the plasmid DNA replicated in mouse cells was recovered. Survival of UV-irradiated plasmid was almost equivalent in both p53-deficient and p53-proficient cells. The frequencies of UV-induced mutation of the supF gene were also the same in both types of cells. However, the distributions of base change mutations in the supF sequence were different between p53-deficient and p53-proficient cells; especially the locations of tandem CpC to TpT changes exhibited a marked difference. Since DNA repair activities of these two types of cell were almost the same, these qualitative differences in UV-induced mutations were probably caused by as yet unidentified differences in other than DNA repair activity.
Ishizaki, K., Nishizawa, K., Mimaki, S., & Aizawa, S. I. (1996). UV-induced mutations of supF gene on a shuttle vector plasmid in p53-deficient mouse cells are qualitatively different from those in wild-type cells. Mutation Research - DNA Repair, 364(1), 43–49. https://doi.org/10.1016/0921-8777(96)00020-1