P53-dependent suppression of the human calcyclin gene (S100A6): the role of Sp1 and of NFkappaB.
Calcyclin (S100A6) is believed to participate in cell cycle control. It was, however, unclear if its expression depends on p53, a key regulator of apoptosis and cell cycle. We therefore performed transcription regulation assays in HeLa cells and found that wild type p53 suppressed the S100A6 promoter up to 12-fold in a dose-dependent manner. In contrast, the well-characterized V143A, R175H, R249S, and L344A p53 mutants cloned from human cancers suppressed this promoter with a 6 to 9-fold lower efficiency. All the sites mediating the p53-dependent suppression were contained in the -167 to +134 fragment of the S100A6 promoter. Separate overexpression of either Sp1 or of NFkappaB only partially counteracted the p53 inhibitory effect on the S100A6 promoter, while simultaneous overexpression of both these transactivators resulted in a complete abolishment of the p53 inhibitory effect on this promoter. Sp1 and NFkappaB binding to the probes resembling their putative binding sites present in the S100A6 promoter was decreased in the presence of wild type p53. We propose that the suppression of S100A6 is yet another mechanism by which p53 inhibits proliferation. Insufficient suppression of this gene by p53 mutants could well be responsible for calcyclin overexpression and cell cycle deregulation observed in cancer tissues.
Króliczak
Weronika
W
Department of Biochemistry, Medical Center of Postgraduate Education, Warszawa, Poland.
Pietrzak
Maciej
M
Puzianowska-Kuznicka
Monika
M
D017209:Apoptosis; D001483:Base Sequence; D001665:Binding Sites; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D016158:Genes, p53; D006367:HeLa Cells; D006801:Humans; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins / Q000235:genetics*; D017384:Sequence Deletion; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013489:Suppression, Genetic; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; D017931:DNA Primers; D016328:NF-kappa B; D011994:Recombinant Proteins; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins; D016329:Sp1 Transcription Factor; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C055351:S100A6 protein, human