title: Roles of thioredoxin reductase 1 and APE/Ref-1 in the control of basal p53 stability and activity.
abstract: The p53 protein is redox-sensitive in vitro but in vivo effectors of this sensitivity are not known. In yeasts deficient for thioredoxin (Trx) reductase (TRR), p53 accumulates in an inactive, oxidized form, suggesting a role for TRR-Trx in controlling p53. In mammalian cells, p53 binds to redox factor-1 (APE/Ref-1), an enzyme containing an abasic endonuclease domain involved in base excision repair, and a thiol reductase domain recycled by Trx and involved in regulating the transcription factor AP-1. To evaluate the role of TRR and APE/Ref-1 in p53 regulation, we have abrogated their expression using RNA interference in cell lines expressing wild-type p53. Inhibition of TRR resulted in accumulation of oxidized Trx and increased levels and DNA-binding activity of p53, with no phosphorylation of Ser15 or Ser20. In contrast, inhibition of APE/Ref-1 accelerated p53 protein turnover, resulting in a decrease in p53 levels and activity. However, inhibition of either TRR or APE/Ref-1 did not prevent activation and accumulation of p53 in response to DNA-damage by doxorubicin. When both factors were inhibited, basal levels of p53 were restored. These results suggest that TRR-Trx and APE/Ref-1 cooperate in the control of basal p53 activity, but not in its induction by DNA-damage.
authors.affiliation: Group of Molecular Carcinogenesis, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France.
authors.forename: Séverine
authors.initials: S
authors.lastname: Seemann
authors.forename: Pierre
authors.initials: P
authors.lastname: Hainaut
mesh_terms: D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D004249:DNA Damage; D017931:DNA Primers; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D006801:Humans; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D018808:Transcription Factor AP-1; D016159:Tumor Suppressor Protein p53; C516124:TXNRD1 protein, human; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase