Serum response element and flanking sequences mediate the synergistic transcriptional activation of c-fos by 12-O-tetradecanoylphorbol-13-acetate and cholera toxin in AKR-2B cells.
12-O-Tetradecanoylphorbol-13-acetate (TPA) and cholera toxin have been shown previously to act synergistically to stimulate traverse of G0-G1 and entry into S phase in quiescent mouse fibroblasts. These agents also have a synergistic effect on the induction of the endogenous c-fos gene, as well as a transfected reporter construct containing the mouse fos promoter/enhancer region from -397 to +1 cloned upstream of luciferase. A detailed mutational analysis of the c-fos-regulatory region revealed that the synergy between TPA and cholera toxin requires multiple discrete elements, including the binding sites for the serum response factor (-308 to -299), p62/Elk-1 (-316 to -309), on the 5' side of the serum response element, and a CCAAT or E box-binding protein(s) on the 3'-flanking side of the serum response element (-303 to -295 or -297 to -292, respectively). The putative cyclic AMP response element (-65 to -58), shown to be activated in a number of cell types after increases in cyclic AMP levels, mediated an induction by TPA but not by cholera toxin in AKR-2B cells, and was not required for the synergistic transactivation induced by the combination of TPA and cholera toxin.
Harvat
B L
BL
Life Sciences Division, Los Alamos National Laboratory, New Mexico 87545, USA.
Wharton
W
W
D000818:Animals; D001481:Basal Metabolism; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology*; D004357:Drug Synergism; D017930:Genes, Reporter; D016762:Genes, fos; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects*
D014157:Transcription Factors; D002772:Cholera Toxin; D008156:Luciferases; D013755:Tetradecanoylphorbol Acetate