title: Ataxia telangiectasia mutated (ATM) and ATM and Rad3-related protein exhibit selective target specificities in response to different forms of DNA damage.
abstract: The ataxia telangiectasia mutated (ATM) and ATR (ATM and Rad3-related) protein kinases exert cell cycle delay, in part, by phosphorylating Checkpoint kinase (Chk) 1, Chk2, and p53. It is well established that ATR is activated following UV light-induced DNA damage such as pyrimidine dimers and the 6-(1,2)-dihydro-2-oxo-4-pyrimidinyl-5-methyl-2,4-(1H,3H)-pyrimidinediones, whereas ATM is activated in response to double strand DNA breaks. Here we clarify the activation of these kinases in cells exposed to IR, UV, and hyperoxia, a condition of chronic oxidative stress resulting in clastogenic DNA damage. Phosphorylation on Chk1(Ser-345), Chk2(Thr-68), and p53(Ser-15) following oxidative damage by IR involved both ATM and ATR. In response to ultraviolet radiation-induced stalled replication forks, phosphorylation on Chk1 and p53 required ATR, whereas Chk2 required ATM. Cells exposed to hyperoxia exhibited growth delay in G1, S, and G2 that was disrupted by wortmannin. Consistent with ATM or ATR activation, hyperoxia induced wortmannin-sensitive phosphorylation of Chk1, Chk2, and p53. By using ATM- and ATR-defective cells, phosphorylation on Chk1, Chk2, and p53 was found to be ATM-dependent, whereas ATR also contributed to Chk1 phosphorylation. These data reveal activated ATM and ATR exhibit selective substrate specificity in response to different genotoxic agents.
authors.affiliation: Department of Environmental Medicine, School of Medicine and Dentistry, the University of Rochester, Rochester, New York 14642, USA.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Helt
authors.forename: William A
authors.initials: WA
authors.lastname: Cliby
authors.forename: Peter C
authors.initials: PC
authors.lastname: Keng
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bambara
authors.forename: Michael A
authors.initials: MA
authors.lastname: O'Reilly
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D004249:DNA Damage / Q000502:physiology* / Q000528:radiation effects; D004268:DNA-Binding Proteins; D017353:Gene Deletion; D006801:Humans; D018496:Hyperoxia / Q000378:metabolism; D007259:Infrared Rays; D008214:Lymphocytes / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D013045:Species Specificity; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins; D014466:Ultraviolet Rays; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D010100:Oxygen; D000077191:Wortmannin