title: ATR kinase activation mediated by MutSalpha and MutLalpha in response to cytotoxic O6-methylguanine adducts.
abstract: S(N)1-type alkylating agents that produce cytotoxic O(6)-methyl-G (O(6)-meG) DNA adducts induce cell cycle arrest and apoptosis in a manner requiring the DNA mismatch repair (MMR) proteins MutSalpha and MutLalpha. Here, we show that checkpoint signaling in response to DNA methylation occurs during S phase and requires DNA replication that gives rise to O(6)-meG/T mispairs. DNA binding studies reveal that MutSalpha specifically recognizes O(6)-meG/T mispairs, but not O(6)-meG/C. In an in vitro assay, ATR-ATRIP, but not RPA, is preferentially recruited to O(6)-meG/T mismatches in a MutSalpha- and MutLalpha-dependent manner. Furthermore, ATR kinase is activated to phosphorylate Chk1 in the presence of O(6)-meG/T mispairs and MMR proteins. These results suggest that MMR proteins can act as direct sensors of methylation damage and help recruit ATR-ATRIP to sites of cytotoxic O(6)-meG adducts to initiate ATR checkpoint signaling.
authors.affiliation: Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: Peggy
authors.initials: P
authors.lastname: Hsieh
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D020137:Base Pair Mismatch; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D018736:DNA Adducts / Q000378:metabolism* / Q000633:toxicity; D004249:DNA Damage; D004260:DNA Repair / Q000502:physiology*; D004268:DNA-Binding Proteins; D004789:Enzyme Activation / Q000187:drug effects; D005090:Exodeoxyribonucleases / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D051719:MutS DNA Mismatch-Binding Protein / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D016196:S Phase; D015398:Signal Transduction
chemical_list: C521194:ATRIP protein, human; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D018736:DNA Adducts; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D006147:Guanine; D004247:DNA; C008449:O-(6)-methylguanine; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D005090:Exodeoxyribonucleases; C429526:three prime repair exonuclease 1; D051719:MutS DNA Mismatch-Binding Protein