Functional interaction between c-Jun and promoter factor Sp1 in epidermal growth factor-induced gene expression of human 12(S)-lipoxygenase.
The functional role of the interaction between c-Jun and simian virus 40 promoter factor 1 (Sp1) in epidermal growth factor (EGF)-induced expression of 12(S)-lipoxygenase gene in human epidermoid carcinoma A431 cells was studied. Coimmunoprecipitation experiments indicated that EGF stimulated interaction between c-Jun and Sp1 in a time-dependent manner. Overexpression of Ha-ras and c-Jun also enhanced the amount of c-Jun binding to Sp1. In addition, the c-Jun dominant negative mutant TAM-67 not only inhibited the coimmunoprecipitated c-Jun binding to Sp1 in a dose-dependent manner in cells overexpressing c-Jun but also reduced promoter activity of the 12(S)-lipoxygenase gene induced by c-Jun overexpression. Treatment of cells with EGF increased the interaction between the Sp1 oligonucleotide and nuclear c-Jun/Sp1 in a time-dependent manner. Furthermore, EGF activated the chimeric promoter consisting of 10 tandem GAL4-binding sites, which replaced the three Sp1-binding sites in the 12(S)lipoxygenase promoter only when coexpressed with GAL4-c-Jun () fusion proteins. These results indicate that the direct interaction between c-Jun and Sp1 induced by EGF cooperatively activated expression of the 12(S)-lipoxygenase gene, and that Sp1 may serve at least in part as a carrier bringing c-Jun to the promoter, thus transactivating the transcriptional activity of 12(S)-lipoxygenase gene.
Chen
B K
BK
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
Chang
W C
WC
D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005656:Fungal Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D011905:Genes, ras; D006801:Humans; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D016755:Proto-Oncogene Proteins c-jun; D029701:Saccharomyces cerevisiae Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D004815:Epidermal Growth Factor; D001092:Arachidonate 12-Lipoxygenase; D013755:Tetradecanoylphorbol Acetate