SAK, a new polo-like kinase, is transcriptionally repressed by p53 and induces apoptosis upon RNAi silencing.
Chip profiling of a p53 temperature-sensitive tumor model identified SAK (Snk/Plk-akin kinase), encoding a new member of polo-like kinases (PLKs), as a gene strongly repressed by wild-type p53. Further characterization revealed that SAK expression was downregulated by wild-type p53 in several tumor cell models. Computer search of a 1.7-kb SAK promoter sequence revealed three putative p53 binding sites, but p53 failed to bind to any of these sites, indicating that SAK repression by p53 was not through a direct p53 binding to the promoter. Transcriptional analysis with luciferase reporters driven by SAK promoter deletion fragments identified SP-1 and CREB binding sites, which together conferred a two-fold SAK repression by p53. However, the repression was not reversed by cotransfection of SP-1 or CREB, suggesting a lack of interference between p53 and SP-1 or CREB. Significantly, p53-mediated SAK repression was largely reversed in a dose-dependent manner by Trichostatin A, a potent histone deacetylase (HDAC) inhibitor, suggesting an involvement of HDAC transcription repressors in SAK repression by p53. Biologically, SAK RNA interference (RNAi) silencing induced apoptosis, whereas SAK overexpression attenuated p53-induced apoptosis. Thus, SAK repression by p53 is likely mediated through the recruitment of HDAC repressors, and SAK repression contributes to p53-induced apoptosis.
Li
Jun
J
Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, 4304 CCGC, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0936, USA.
Tan
Mingjia
M
Li
Ling
L
Pamarthy
Deepika
D
Lawrence
Theodore S
TS
Sun
Yi
Y
D000595:Amino Acid Sequence; D017209:Apoptosis; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D003001:Cloning, Molecular; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D053938:DNA Fragmentation; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D005047:Etoposide / Q000494:pharmacology; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000502:physiology*; D034622:RNA Interference; D012984:Software; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D017362:Cyclic AMP Response Element-Binding Protein; D016329:Sp1 Transcription Factor; D016159:Tumor Suppressor Protein p53; D005047:Etoposide; D008156:Luciferases; C490219:PLK4 protein, human; D017346:Protein Serine-Threonine Kinases