The DNA crosslink-induced S-phase checkpoint depends on ATR-CHK1 and ATR-NBS1-FANCD2 pathways.
The genetic syndrome Fanconi anemia (FA) is characterized by aplastic anemia, cancer predisposition and hypersensitivity to DNA interstrand crosslinks (ICLs). FA proteins (FANCs) are thought to work in pathway(s) essential for dealing with crosslinked DNA. FANCs interact with other proteins involved in both DNA repair and S-phase checkpoint such as BRCA1, ATM and the RAD50/MRE11/NBS1 (RMN) complex. We deciphered the previously undefined pathway(s) leading to the ICLs-induced S-phase checkpoint and the role of FANCs in this process. We found that ICLs activate a branched pathway downstream of the ATR kinase: one branch depending on CHK1 activity and the other on the FANCs-RMN complex. The transient slow-down of DNA synthesis was abolished in cells lacking ATR, whereas CHK1-siRNA-treated cells, NBS1 or FA cells showed partial S-phase arrest. CHK1 RNAi in NBS1 or FA cells abolished the S-phase checkpoint, suggesting that CHK1 and FANCs/NBS1 proteins work on parallel pathways. Furthermore, we found that ICLs trigger ATR-dependent FANCD2 phosphorylation and FANCD2/ATR colocalization. This study demonstrates a novel relationship between the FA pathway(s) and the ATR kinase.
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Pietro
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UPR 2169 du CNRS, Institut Gustave Roussy PR2, Villejuif Cedex, France.
Rosselli
Filippo
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D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D000071877:Checkpoint Kinase 1; D004247:DNA / Q000378:metabolism*; D052236:Fanconi Anemia Complementation Group D2 Protein; D006801:Humans; D008730:Methoxsalen / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D016196:S Phase; D015398:Signal Transduction / Q000187:drug effects
D018797:Cell Cycle Proteins; C499905:FANCD2 protein, human; D052236:Fanconi Anemia Complementation Group D2 Protein; C112156:NBN protein, human; D009687:Nuclear Proteins; D004247:DNA; D011494:Protein Kinases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D008730:Methoxsalen