CtIP-dependent DNA resection is required for DNA damage checkpoint maintenance but not initiation.
To prevent accumulation of mutations, cells respond to DNA lesions by blocking cell cycle progression and initiating DNA repair. Homology-directed repair of DNA breaks requires CtIP-dependent resection of the DNA ends, which is thought to play a key role in activation of ATR (ataxia telangiectasia mutated and Rad3 related) and CHK1 kinases to induce the cell cycle checkpoint. In this paper, we show that CHK1 was rapidly and robustly activated before detectable end resection. Moreover, we show that the key resection factor CtIP was dispensable for initial ATR-CHK1 activation after DNA damage by camptothecin and ionizing radiation. In contrast, we find that DNA end resection was critically required for sustained ATR-CHK1 checkpoint signaling and for maintaining both the intra-S- and G2-phase checkpoints. Consequently, resection-deficient cells entered mitosis with persistent DNA damage. In conclusion, we have uncovered a temporal program of checkpoint activation, where CtIP-dependent DNA end resection is required for sustained checkpoint signaling.
Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.
Arne Nedergaard
AN
Kousholt
Kasper
K
Fugger
Saskia
S
Hoffmann
Brian D
BD
Larsen
Tobias
T
Menzel
Alessandro A
AA
Sartori
Claus Storgaard
CS
Sørensen
D002352:Carrier Proteins / Q000378:metabolism*; D059447:Cell Cycle Checkpoints; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage; D004706:Endodeoxyribonucleases; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction
D002352:Carrier Proteins; D009687:Nuclear Proteins; D004247:DNA; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D004706:Endodeoxyribonucleases; C410741:RBBP8 protein, human