Characterization of a mutant rat kangaroo cell line with alterations in the cell cycle and DNA repair

Using a positive selection system for isolating DNA replication and repair related mutants, we isolated a clone from a rat kangaroo cell line (PtK2) t hat has increased sensitivity to UV light. Characterization of this clone i ndicated normal post-replication repair after UV irradiation, and normal re moval rates of cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimidone photoproducts by excision repair. However, this cell line has decreased abi lity to make early incisions on damaged DNA, possibly indicating a defect i n preferential repair of actively transcribed genes, and a slower cell prol iferation rate, including a longer S-phase. This phenotype reinforces the p resent notion that control of key mechanisms in cell metabolism, such as ce ll cycle control, repair, transcription and cell death, can be linked.