Identification of a second region upstream of the mouse heme oxygenase-1 gene that functions as a basal level and inducer-dependent transcription enhancer.
A 161-base pair fragment (AB1) approximately 10 kilobase pairs upstream of the transcription start site of the mouse heme oxygenase-1 gene functions as a basal level and inducer-dependent enhancer. AB1/chloramphenicol acetyltransferase fusion genes stably transfected into mouse hepatoma (Hepa) cells or L929 fibroblasts were activated 7-8- or 17-22-fold, respectively, after treatment of the cells with either CdCl2 or heme. The AB1 fragment is composed largely of three tandem repeats containing two conserved core elements, A and B. Part of core element A (TCCGGAGCTGTG) resembles the consensus-binding site for transcription factor AP-4, whereas core element B (GCTGAGTCANGG) includes the consensus-binding site (TGAGTCA) for the AP-1 family of transcription factors. Nuclear proteins from Hepa cells did not bind to any of the core A elements, but bound to all three copies of the core B element. AB1 derivatives with one or two mutant AP-1-binding elements exhibited reduced but measurable inducer-dependent enhancer activity, but mutation of all three AP-1-binding sites abolished activation by CdCl2 and heme and also by mercury chloride, zinc chloride, H2O2, sodium arsenate, and 12-O-tetradecanoylphorbol-13-acetate. Pretreatment of stably transfected L929 cells with protein kinase C inhibitors, but not with tyrosine kinase inhibitors or N-acetylcysteine, abrogated 12-O-tetradecanoylphorbol-13-acetate-dependent activation of the AB1/chloramphenicol acetyltransferase fusion gene. Induction by H2O2 was unaffected by the kinase inhibitors, but completely abolished by N-acetylcysteine. Heme-dependent induction was not significantly affected by any of these chemicals.
Alam
J
J
Department of Molecular Genetics, Alton Ochsner Medical Foundation, New Orleans, Louisiana 70121, USA.
Camhi
S
S
Choi
A M
AM
D000111:Acetylcysteine / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D004790:Enzyme Induction; D005796:Genes; D019833:Genistein; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis / Q000235:genetics*; D007529:Isoflavones / Q000494:pharmacology; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009281:Naphthalenes; D009687:Nuclear Proteins / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology; D011083:Polycyclic Compounds / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D019311:Staurosporine; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D000470:Alkaloids; D004268:DNA-Binding Proteins; D007529:Isoflavones; D009281:Naphthalenes; D009687:Nuclear Proteins; D010636:Phenols; D011083:Polycyclic Compounds; D047428:Protein Kinase Inhibitors; D011993:Recombinant Fusion Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C061465:calphostin complex; C062898:lavendustin A; D019833:Genistein; D006419:Heme Oxygenase (Decyclizing); D019311:Staurosporine; D000111:Acetylcysteine