Identification and characterization of cis-acting regulatory elements for the expression of the human aromatase cytochrome P-450 gene

Abstract

CYP19, the human aromatase cytochrome P-450 (P450arom) gene, encodes an enzyme which converts androgens to estrogens by three successive hydroxylation reactions by coupling with NADPH-cytochrome P-450 reductase. In the present study, we have characterized two cis-acting transcriptional regulatory elements of CYP19, termed as hATRE-1 (human aromatase cytochrome P-450 gene transcriptional regulatory element-1) ([sequence: see text]) and hATRE-2 ([sequence: see text]). These sequences are located between -2238 and -2214, and between -2141 and -2098 relative to the major cap site of the gene, respectively. Transient expression analysis in human BeWo choriocarcinoma cells, in which CYP19 is expressed, shows that hATRE-1 represses the expression of the bacterial chloramphenicol acetyltransferase reporter gene driven by the promoter of CYP19, whereas hATRE-2 enhances the reporter gene expression in response to 12-O-tetradecanoylphorbol 13-acetate. Electrophoretic mobility shift analysis indicates that nuclear binding factors specific to hATRE-1 are present in BeWo cells, but not in HeLa cells nor in TYK-nu cells that lack the expression of CYP19. In contrast, nuclear binding factors to hATRE-2 are present not only in BeWo cells but also in the latter two types of cells. Nevertheless, hATRE-2 does not affect the reporter gene expression in HeLa cells and TYK-nu cells. These results indicate that hATRE-1 and hATRE-2 are cis-acting transcriptional regulatory elements involving in the regulation of the cell type-specific expression of CYP19.