Purified transcription factor AP-1 interacts with TPA-inducible enhancer elements.
The enhancer-binding protein AP-1 has been purified to greater than 95% homogeneity from HeLa cells by sequence-specific DNA affinity chromatography and identified as a 47 kd polypeptide. Purified AP-1 activates transcription in vitro of the wild-type human metallothionein IIA (hMT IIA) gene but not mutant hMT IIA promoters lacking AP-1 recognition sites. DNAase I protection analysis indicates that genetically defined enhancer elements in hMT IIA, SV40, and the human collagenase gene contain high-affinity AP-1-binding sites, each with a conserved recognition motif, TGACTCA. These three genes are transcriptionally induced by treatment of cells with the tumor promoter TPA. Here we demonstrate that multiple synthetic copies of the consensus AP-1-binding site can act as TPA-inducible enhancers in various plasmid constructs after transfection into HeLa cells. These findings suggest that AP-1 is a transcription factor that functions by interacting with a specific enhancer element, and that its activities may be modulated by treatment of cells with TPA, known to stimulate protein kinase C.
D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005809:Genes, Regulator; D006801:Humans; D008668:Metallothionein / Q000235:genetics*; D003012:Microbial Collagenase / Q000235:genetics*; D008970:Molecular Weight; D009154:Mutation; D016755:Proto-Oncogene Proteins c-jun; D013539:Simian virus 40 / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics* / Q000302:isolation & purification
D004268:DNA-Binding Proteins; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D008668:Metallothionein; D003012:Microbial Collagenase; D013755:Tetradecanoylphorbol Acetate