Inhibition of mutant p53 phosphorylation at serine 15 or serine 315 partially restores the function of wild-type p53.
The tumor suppressor protein p53 is a phosphoprotein and has growth and transformation suppression functions. Phosphorylation of wild-type p53 is known to modulate its function. To investigate the role of phosphorylation in modulating the functions of mutant p53, we constructed a series of phosphorylation site mutants based on mutant p53 Ala143 (p53-143) and p53 His175 (p53-175). When transfected into p53-negative Saos-2 cells, parental mutant p53-143 and p53-175 abolished both growth suppression and induction of apoptosis. However, DNA-activated protein kinase (DNA-PK) or cyclin-dependent kinase (cdks) phosphorylation site double mutants partially restored the growth suppression and induction of apoptosis and recovered the p53-specific DNA binding activity. We also observed a difference in sensitivity to calpain from parental mutants p53-175 and p53-175/15 or p53-175/315. These results suggest that the lack of phosphorylation at either the DNA-PK or cdks site in p53 mutants partially restores the wild-type functions by altering their conformation.
Sugikawa
E
E
Drug Discovery Research Laboratory, Tanabe Seiyaku Co., Ltd., 2-2-50 Kawagishi, Saitama, Toda, 335-8505, Japan.
Yazaki
N
N
Tsunoda
S
S
Nakanishi
N
N
Ohashi
M
M
D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002154:Calpain / Q000494:pharmacology; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D006801:Humans; D009687:Nuclear Proteins; D010766:Phosphorylation; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D012694:Serine; D004247:DNA; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; D002154:Calpain