WRN counteracts the NHEJ pathway upon camptothecin exposure.
We investigated the function of the interaction between WRN (Werner syndrome gene product) and Ku70 and between WRN and DNA-PKcs, which are components of the DNA-PKcs/Ku70/Ku80 complex, by generating KU70(-/-)/WRN(-/-) and DNA-PKcs(-/-/-)/WRN(-/-) double-gene knockout chicken DT40 cells. When treated with camptothecin (CPT), an inhibitor of DNA topoisomerase I, WRN(-/-) cells showed higher sensitivity than wild-type cells, whereas KU70(-/-) and DNA-PKcs(-/-/-) cells showed hyper-resistance. Disruption of KU70 or DNA-PKcs suppressed the sensitivity of WRN(-/-) cells to CPT, rendering them as resistant to CPT treatment as KU70(-/-) and DNA-PKcs(-/-/-) cells. On the other hand, CPT sensitivity of BLM(-/-) cells, which are defective in a RecQ helicase similar to WRN, was enhanced by deletion of KU70. The implications for the function of WRN in the non-homologous end-joining pathway of DNA repair involving Ku70 and DNA-PKcs, which may be the cause of lethality in the presence of CPT, will be discussed.
Otsuki
Makoto
M
Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba 6-3, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Seki
Masayuki
M
Kawabe
Yoh-ichi
Y
Inoue
Eri
E
Dong
Yu Peng
YP
Abe
Takuya
T
Kato
Genta
G
Yoshimura
Akari
A
Tada
Shusuke
S
Enomoto
Takemi
T
D034961:Antigens, Nuclear / Q000378:metabolism; D015139:Blotting, Southern; D002166:Camptothecin / Q000494:pharmacology*; D002460:Cell Line; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005090:Exodeoxyribonucleases; D006801:Humans; D000072200:Ku Autoantigen; D053484:RecQ Helicases / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071657:Werner Syndrome Helicase
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D051747:DNA-Activated Protein Kinase; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D002166:Camptothecin