title: p53 regulates Hsp90beta during arsenite-induced cytotoxicity in glutathione-deficient cells.
abstract: p53, a tumor suppressor and transcription factor, is a critical modulator in the cellular response to stress. Exposure of glutathione-deficient GCS-2 cells to arsenite significantly phosphorylated and stabilized p53. In addition, p53 transcriptionally repressed Hsp90beta gene expression. Mutation analysis revealed a p53 binding site in the 5' flanking region responsible for the regulation of Hsp90beta gene. Electrophoretic mobility shift assay showed that p53 is bound to Hsp90beta promoter region. ATM kinase, a major determinant in the modulation of p53 specifically affected its phosphorylation at Ser-15. ATM kinase-mediated phosphorylation of p53 is regulated through phosphorylation of Chk2. Down-regulation of ATM and Chk2 by their small interfering RNAs (siRNAs) attenuated the arsenite-induced phosphorylation of p53 and restored Hsp90beta mRNA levels. Taken together, these findings suggest that arsenite acts through ATM and Chk2 to induce phosphorylation of p53. This results in the transcriptional repression of Hsp90beta, under GSH-deficient conditions which may play a role in arsenic-mediated pathogenesis.
authors.affiliation: Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. geetha_habib@yahoo.com
authors.forename: Geetha M
authors.initials: GM
authors.lastname: Habib
mesh_terms: D000818:Animals; D018053:Arsenites / Q000633:toxicity*; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D064447:Checkpoint Kinase 2; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D004785:Environmental Pollutants / Q000633:toxicity*; D005978:Glutathione / Q000172:deficiency*; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D009154:Mutation; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018053:Arsenites; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D004785:Environmental Pollutants; D018841:HSP90 Heat-Shock Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D064447:Checkpoint Kinase 2; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; C578633:Chek2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D005978:Glutathione; C015001:arsenite