Cis-acting elements regulating the placenta-specific promoter of the bovine Cyp19 gene.
Cyp19 encodes aromatase cytochrome P450, the key enzyme of oestrogen biosynthesis. In the bovine placenta, the majority of Cyp19 transcripts include a 5' untranslated region which is encoded by exon 1.1; this suggests that its 5'-flanking region is the predominant placental promoter. The aim of the present investigation was to examine the promoter activity of this region and to map cis-acting regulatory elements in order to improve our understanding of the complex regulation of this gene within the placenta. As an initial approach, human JEG-3 choriocarcinoma cells were transiently transfected with reporter-gene constructs consisting of different 5'-flanking sequences of exon 1.1 fused to the luciferase gene as a reporter. To localise and further characterise functional cis-acting elements, targeted point mutations and electrophoretic mobility-shift experiments were used. The data demonstrate, for the first time, (1) that the bovine exon 1.1 5'-flanking sequence is an active promoter, (2) that 404 bp of this region are sufficient for constitutive reporter-gene expression in JEG-3 cells and (3) that the region includes at least two different enhancer elements; the data also suggest (4) that one of these elements consists of the E-box motif CATGTG and that the second enhancer element includes the half-site hexameric sequence AGGTCA and additional nucleotides flanking this element upstream.
Kalbe
C
C
Research Institute for the Biology of Farm Animals, Molecular Biology Research Unit, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
Fürbass
R
R
Schwerin
M
M
Vanselow
J
J
D000818:Animals; D001141:Aromatase / Q000235:genetics*; D001483:Base Sequence / Q000235:genetics; D002417:Cattle / Q000235:genetics*; D002478:Cells, Cultured; D005091:Exons; D017353:Gene Deletion; D005809:Genes, Regulator / Q000235:genetics; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000502:physiology; D010920:Placenta / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D013237:Stereoisomerism; D014407:Tumor Cells, Cultured
D009687:Nuclear Proteins; D001141:Aromatase