201. Transcriptional Regulation of the Human FTZ-F1 Gene Encoding Ad4BP/SF-1
- Author
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Toshihiko Yanase, Ryoichi Takayanagi, Hajime Nawata, Isao Ichino, Kiminobu Goto, and Koichi Oba
- Subjects
Chloramphenicol O-Acetyltransferase ,Steroidogenic factor 1 ,Transcription, Genetic ,Receptors, Retinoic Acid ,Genetic Vectors ,Molecular Sequence Data ,Fushi Tarazu Transcription Factors ,Receptors, Cytoplasmic and Nuclear ,E-box ,Regulatory Sequences, Nucleic Acid ,Biology ,Steroidogenic Factor 1 ,Transfection ,Biochemistry ,Mice ,Transactivation ,Sequence Homology, Nucleic Acid ,Tumor Cells, Cultured ,Transcriptional regulation ,Animals ,Humans ,Luciferases ,Molecular Biology ,DNA Primers ,Electrophoresis, Agar Gel ,Homeodomain Proteins ,Regulation of gene expression ,Genetics ,Base Sequence ,DAX-1 Orphan Nuclear Receptor ,Reverse Transcriptase Polymerase Chain Reaction ,YY1 ,Haplorhini ,General Medicine ,DNA-Binding Proteins ,Repressor Proteins ,Gene Expression Regulation ,Regulatory sequence ,GATAD2B ,Adrenal Cortex ,Mutagenesis, Site-Directed ,Cattle ,Transcription Factors - Abstract
Ad4BP, also known as SF-1, is a steroidogenic tissue-specific transcription factor that is also essential for adrenal and gonadal development. Two mechanisms for the transcriptional regulation of the mammalian FTZ-F1 gene encoding Ad4BP in adrenocortical cells have been proposed in the previous studies: the crucial role of a cis-element, an E box for the steroidogenic cell-specific expression of mouse and rat FTZ-F1 genes, and a possible autoregulatory mechanism of the rFTZ-F1 gene by Ad4BP itself through binding to the Ad4 (or SF-1) site in the first intron. In the present study, the transcriptional regulation of the human FTZ-F1 gene in adrenocortical cells was investigated from several angles, including the above two mechanisms. Using a series of deletion analyses of the 5'-flanking region of the hFTZ-F1 gene and site-directed mutagenesis for transient transfection studies, an E box element, CACGTG at -87/-82 from the transcriptional start site, was also found to be essential for the transcription of the hFTZ-F1 gene in mouse or human adrenocortical cell lines as well as in non-steroidogenic CV-1 cells. Despite the presence of a corresponding Ad4 site, CCAAGGCC at +163/+156 in the first intron of the hFTZ-F1 gene, an autoregulatory mechanism through the Ad4 site was found to be unlikely in the hFTZ-F1 gene mainly due to site-directed mutagenesis. In addition, the forced expression of Ad4BP had little effect on hFTZ-F1 gene transcription in non-steroidogenic CV-1 cells. Such Ad4BP-independent regulation of the hFTZ-F1 gene was in striking contrast to the regulation of steroidogenic CYP genes, such as the human CYP11A gene, in which the proximal promoter activity is Ad4BP-dependent and the transactivation by Ad4BP is silenced by DAX-1. Even though the Ad4BP-dependent transcriptional regulation of the DAX-1 gene has been reported, DAX-1 did not affect the transcriptional activity of the hFTZ-F1 gene in our study. Taken together, these observations suggest that the E box is indeed required for the expression of the FTZ-F1 gene, at least in mammalian species, but may not determine the tissue-specific expression of the hFTZ-F1 gene, and that, unlike the steroidogenic CYP gene, the regulation of the hFTZ-F1 gene appears to be independent of both Ad4BP and DAX-1.
- Published
- 2000