UV sensitivity and impaired nucleotide excision repair in DNA-dependent protein kinase mutant cells.
DNA-dependent protein kinase (DNA-PK), a member of the phosphatidyl-inositol (PI)3-kinase family, is involved in the repair of DNA double-strand breaks. Its regulatory subunit, Ku, binds to DNA and recruits the kinase catalytic subunit (DNA-PKcs). We show here a new role of DNA-PK in the modulation of the process of nucleotide excision repair (NER) in vivo since, as compared with their respective parental cell lines, DNA-PK mutants (scid , V-3 and xrs 6 cells) exhibit sensitivity to UV-C irradiation (2.0- to 2.5-fold) and cisplatin ( approximately 3- to 4-fold) associated with a decreased activity (40-55%) of unscheduled DNA synthesis after UV-C irradiation. Moreover, we observed that wortmannin sensitized parental cells in vivo when combined with either cisplatin or UV-C light, but had no effect on the DNA-PKcs deficient scid cells. Despite a lower repair synthesis activity (approximately 2-fold) measured in vitro with nuclear cell extracts from DNA-PK mutants, a direct involvement of DNA-PK in the NER reaction in vitro has not been observed. This study establishes a regulatory function of DNA-PK in the NER process in vivo but rules out a physical role of the complex in the repair machinery at the site of the DNA lesion.
Muller
C
C
Institut de Pharmacologie et de Biologie Structurale (CNRS, UPR 9062), 205 route de Narbonne, 31077 Toulouse Cedex, France.
Calsou
P
P
Frit
P
P
Cayrol
C
C
Carter
T
T
Salles
B
B
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001761:Bleomycin / Q000494:pharmacology; D016466:CHO Cells; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002945:Cisplatin / Q000494:pharmacology; D006224:Cricetinae; D004260:DNA Repair / Q000235:genetics* / Q000502:physiology; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D009687:Nuclear Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D011836:Radiation Tolerance / Q000235:genetics* / Q000502:physiology; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D014466:Ultraviolet Rays; D000077191:Wortmannin
D000730:Androstadienes; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011838:Radiation-Sensitizing Agents; D001761:Bleomycin; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D002945:Cisplatin; D000077191:Wortmannin