title: Single-stranded DNA orchestrates an ATM-to-ATR switch at DNA breaks.
abstract: ATM and ATR are two master checkpoint kinases activated by double-stranded DNA breaks (DSBs). ATM is critical for the initial response and the subsequent ATR activation. Here we show that ATR activation is coupled with loss of ATM activation, an unexpected ATM-to-ATR switch during the biphasic DSB response. ATM is activated by DSBs with blunt ends or short single-stranded overhangs (SSOs). Surprisingly, the activation of ATM in the presence of SSOs, like that of ATR, relies on single- and double-stranded DNA junctions. In a length-dependent manner, SSOs attenuate ATM activation and potentiate ATR activation through a swap of DNA-damage sensors. Progressive resection of DSBs directly promotes the ATM-to-ATR switch in vitro. In cells, the ATM-to-ATR switch is driven by both ATM and the nucleases participating in DSB resection. Thus, single-stranded DNA orchestrates ATM and ATR to function in an orderly and reciprocal manner in two distinct phases of DSB response.
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Bunsyo
authors.initials: B
authors.lastname: Shiotani
authors.forename: Lee
authors.initials: L
authors.lastname: Zou
mesh_terms: D017766:Acid Anhydride Hydrolases; D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D045643:DNA Repair Enzymes / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004706:Endodeoxyribonucleases; D004789:Enzyme Activation; D005090:Exodeoxyribonucleases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D000076228:MRE11 Homologue Protein; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; C112156:NBN protein, human; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D000076228:MRE11 Homologue Protein; C410741:RBBP8 protein, human; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes