Chk1-deficient tumour cells are viable but exhibit multiple checkpoint and survival defects.
The conserved protein kinase Chk1 is believed to play an important role in checkpoint responses to aberrant DNA structures; however, genetic analysis of Chk1 functions in metazoans is complicated by lethality of Chk1-deficient embryonic cells. We have used gene targeting to eliminate Chk1 function in somatic DT40 B-lymphoma cells. We find that Chk1-deficient DT40 cells are viable, but fail to arrest in G(2)/M in response to and are hypersensitive to killing by ionizing radiation. Chk1-deficient cells also fail to maintain viable replication forks or suppress futile origin firing when DNA polymerase is inhibited, leading to incomplete genome duplication and diminished cell survival after release from replication arrest. In contrast to embryonic cells, however, Chk1 is not required to delay mitosis when DNA synthesis is inhibited. Thus, Chk1 is dispensable for normal cell division in somatic DT40 cells but is essential for DNA damage-induced G(2)/M arrest and a subset of replication checkpoint responses. Furthermore, Chk1-dependent processes promote tumour cell survival after perturbations of DNA structure or metabolism.
Zachos
George
G
Beatson Institute for Cancer Research, Cancer Research UK Beatson Laboratories, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK.
Rainey
Michael D
MD
Gillespie
David A F
DA
D000595:Amino Acid Sequence; D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology; D002455:Cell Division / Q000502:physiology*; D002470:Cell Survival; D000071877:Checkpoint Kinase 1; D002645:Chickens; D004249:DNA Damage; D004261:DNA Replication / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018390:Gene Targeting; D018816:Genes, cdc; D006801:Humans; D016393:Lymphoma, B-Cell / Q000378:metabolism; D008969:Molecular Sequence Data; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011839:Radiation, Ionizing; D016415:Sequence Alignment; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D016590:Aphidicolin; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1