title: An ATM- and Rad3-related (ATR) signaling pathway and a phosphorylation-acetylation cascade are involved in activation of p53/p21Waf1/Cip1 in response to 5-aza-2'-deoxycytidine treatment.
abstract: Most agents that damage DNA act through posttranslational modifications of p53 and activate its downstream targets. However, whether cellular responses to nucleoside analogue-induced DNA damage also operate through p53 posttranslational modification has not been reported. In this study, the relationship between p53 activation and its posttranslational modifications was investigated in the human cancer cell lines A549 and HCT116 in response to 5-aza-2'-deoxycytidine (5-aza-CdR) or cytarabine treatment. 5-Aza-CdR induces p53 posttranslational modifications through activation of an ATM- and Rad3-related (ATR) signaling pathway, and 5-aza-CdR-induced association of replication protein A with chromatin is required for the binding of ATR to chromatin. Upon treatment with 5-aza-CdR, ATR activation is clearly associated with p53 phosphorylation at Ser(15), but not at Thr(18), Ser(20), or Ser(37). This specific p53 phosphorylation at Ser(15) in turn results in acetylation of p53 at Lys(320) and Lys(373)/Lys(382) through transcriptional cofactors p300/CBP-associated factor and p300, respectively. These p53 posttranslational modifications are directly responsible for 5-aza-CdR induced p21(Waf1/Cip1) expression because the binding activity of acetylated p53 at Lys(320)/Lys(373)/Lys(382) to the p21(Waf1/Cip1) promoter, as well as p21(Waf1/Cip1) expression itself are significantly increased after 5-aza-CdR treatment. It is of interest that p53 phosphorylation at Ser(15) and acetylations at Lys(320)/Lys(373)/Lys(382) mutually interact in the 5-aza-CdR induced p21(Waf1/Cip1) expression shown by transfection of artificially mutated p53 expression vectors including S15A, K320R, and K373R/K382R into p53-null H1299 cells. These data taken together show for the first time that 5-aza-CdR activates the ATR signaling pathway, which elicits a specific p53 phosphorylation-acetylation cascade to induce p21(Waf1/Cip1) expression.
authors.affiliation: Department of Biochemistry and Molecular Biology, Peking University Health Science Center, #38 Xueyuan Road, Beijing, China.
authors.forename: Haiying
authors.initials: H
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Lian
authors.initials: L
authors.lastname: Li
authors.forename: Michael A
authors.initials: MA
authors.lastname: McNutt
authors.forename: Lipeng
authors.initials: L
authors.lastname: Wu
authors.forename: Shaoli
authors.initials: S
authors.lastname: Lu
authors.forename: Yu
authors.initials: Y
authors.lastname: Yu
authors.forename: Wen
authors.initials: W
authors.lastname: Zhou
authors.forename: Jingnan
authors.initials: J
authors.lastname: Feng
authors.forename: Guolin
authors.initials: G
authors.lastname: Chai
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Zhu
mesh_terms: D000107:Acetylation; D064007:Ataxia Telangiectasia Mutated Proteins; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D017931:DNA Primers / Q000235:genetics; D000077209:Decitabine; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051716:Replication Protein A / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D017931:DNA Primers; D051716:Replication Protein A; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D000077209:Decitabine; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D001374:Azacitidine