Transcriptional regulation of the CDK inhibitor p16INK4a gene by a novel pRb-associated repressor, RBAR1.
p16, also known as INK4a, CDKN2, or MTS1, plays an important role in the control of the cell cycle progression, and retinoblastoma protein (pRb) is suggested to be involved in the transcriptional regulation of p16. However, it is not fully understood how pRb regulates transcription of the p16 gene. Nuclear proteins prepared only from the pRb-nonfunctional human tumor cells were found to bind to the 5'-flanking sequence of the p16 gene in the presence of Zn2+ by electrophoretic mobility shift assay (EMSA). EMSA using mutagenized 5'-flanking sequences as competitors suggested that the sequence at position -97 to -87 relative to first ATG of the p16 gene was critical for protein binding. Transient reporter assay indicated that the sequence identified by EMSA acted as a silencer element in the pRb-nonfunctional tumor cells, showing the presence of a transcriptional repressor associated with functional pRb (RBAR1).
Kaneko
S
S
Department of Biochemistry, Mie University Faculty of Medicine, Japan.
Nishioka
J
J
Tanaka
M
M
Nakashima
K
K
Nobori
T
T
D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000032:analysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D016160:Retinoblastoma Protein / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009838:Oligodeoxyribonucleotides; D012097:Repressor Proteins; D016160:Retinoblastoma Protein; D018844:Cyclin-Dependent Kinases