Differential activation of the rat phenylethanolamine N-methyltransferase gene by Sp1 and Egr-1.
The rat phenylethanolamine N-methyltransferase (PNMT) gene contains overlapping consensus elements for the Sp1 and Egr-1 transcription factors located at -45 bp and -165 bp in the PNMT promoter. In the present study, we show that Sp1 and Egr-1 can specifically bind to these overlapping elements, that this binding appears to be mutually exclusive, and that binding site occupancy is dependent upon the concentration of each factor and its binding affinity for each site. Egr-1 binds to the -165 bp site with relatively high affinity (IC50 = 14 nM) and to the -45 bp site with relatively low affinity (IC50 = 1360 nM), whereas Sp1 binds to both sites with intermediate affinities (IC50 = 210 and 140 nM, respectively). Consistent with the DNA-binding data, Egr-1 stimulates PNMT promoter activity primarily through interaction with the -165 bp site, while Sp1 stimulates PNMT promoter activity by interacting with both the -45 bp and the -165 bp sites. These results show that Sp1 and Egr-1 are capable of differentially activating PNMT gene expression, thereby suggesting that different stimuli may control the activity of the PNMT gene by selectively regulating Sp1 and/or Egr-1.
Ebert
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Nancy Pritzker Laboratory of Developmental and Molecular Neurobiology, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, California 94305-5485, USA.
Wong
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D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004268:DNA-Binding Proteins / Q000502:physiology*; D051766:Early Growth Response Protein 1; D015971:Gene Expression Regulation, Enzymologic; D017874:Immediate-Early Proteins; D008969:Molecular Sequence Data; D010625:Phenylethanolamine N-Methyltransferase / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D016329:Sp1 Transcription Factor / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D010625:Phenylethanolamine N-Methyltransferase