Suppression of glutathione transferase P expression by glucocorticoid.
A strong enhancer element, GPEI, of the glutathione transferase P gene (GST-P) gene is composed of two phorbol 12-O-tetradecanoate 13-acetate (TPA) responsive element (TRE)-like sequences at opposite orientation. Unlike TRE sequences of other genes, GPEI exhibits a strong enhancer activity in F9 cells, which contains little AP-1. GPEI bound to AP-1 In vitro and GST-P expression was activated by TPA and exogenously introduced c-jun gene in a rat fibroblast cell line. Both the stimulated expression of GST-P gene by TPA and that by over-expressed c-Jun were suppressed to the basal level by dexamethasone, an inhibitor of AP-1. Basal expression of GST-P gene, however, was not inhibited by dexamethasone. Transfected chloramphenicol acetyltransferase (CAT) gene having GPEI also behaved as the endogenous GST-P gene. These results indicate that the GPEI is activated by AP-1 but constitutive activity of this enhancer in a rat fibroblast cell line 3Y1 cells is due to some unknown mechanism other than AP-1.
Sakai
M
M
Department of Biochemistry, Hokkaido University School of Medicine, Sapporo, Japan.
Muramatsu
M
M
Nishi
S
S
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology*; D004742:Enhancer Elements, Genetic; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D005982:Glutathione Transferase / Q000235:genetics*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
D046911:Macromolecular Substances; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D003907:Dexamethasone; D015500:Chloramphenicol O-Acetyltransferase; D005982:Glutathione Transferase; D013755:Tetradecanoylphorbol Acetate