Sp1-like sequences mediate human caspase-3 promoter activation by p73 and cisplatin.
Caspase-3 is a cysteine protease that plays a central role in the execution of apoptosis induced by a wide variety of stimuli. However, little is known about the mechanisms involved in the regulation of caspase-3 gene transcription. This study was carried out to characterize the human caspase-3 promoter and to understand the mechanisms involved in the induction of caspase-3 gene expression in response to the anticancer drug cisplatin and p73. Caspase-3 gene expression was induced by treatment of cells with cisplatin, which also induced p73 protein in HeLa and K562 cells. The human caspase-3 promoter was cloned and characterized. p73beta strongly activated the caspase-3 promoter, whereas p73alpha showed less activation. Cisplatin treatment increased caspase-3 promoter activity. Basal and cisplatin-induced promoter activity was inhibited by the p73 inhibitor p73DD. Deletion analysis defined a minimal promoter of 120 base pairs, which showed good basal and p73beta-induced activity. The examination of the minimal promoter sequence showed several putative Sp1 sites, but no p53/p73 site. The caspase-3 promoter was activated by Sp1 in Sp1-deficient Drosophila SL-2 cells. Sp1-induced promoter activity was further enhanced by p73beta in SL-2 cells. Mutation of Sp1 sites in the minimal promoter resulted in a loss of basal and p73-induced promoter activity. These results show that caspase-3 gene transcription is induced by cisplatin, which is mediated partly by p73. We have identified p73 and Sp1 as activators of the caspase-3 promoter. Sp1-like sequences in the minimal promoter not only sustain basal promoter activity, but also mediate p73-induced activation of the promoter.
Sudhakar
Cherukuri
C
Centre for Cellular and Molecular Biology, Hyderabad, India.
Jain
Nishant
N
Swarup
Ghanshyam
G
D000970:Antineoplastic Agents / Q000494:pharmacology*; D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D053148:Caspase 3 / Q000235:genetics*; D002945:Cisplatin / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000502:physiology*; D004789:Enzyme Activation; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D012689:Sequence Homology, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000502:physiology*
D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D053148:Caspase 3; D002945:Cisplatin