Transcriptional regulation of the human FTZ-F1 gene encoding Ad4BP/SF-1.
Transcriptional regulation of the human FTZ-F1 gene encoding Ad4BP/SF-1.
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编码 Ad4BP/SF-1 的人类 FTZ-F1 基因的转录调控。
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
Hajime Nawata
中科院分区：
文献类型：
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作者：
K. Oba;Toshihiko Yanase;I. Ichino;K. Goto;R. Takayanagi;Hajime Nawata
Ad 4 BP，也称为SF-1，是一种类固醇生成组织特异性转录因子，也是肾上腺和性腺发育所必需的。在先前的研究中提出了编码Ad 4 BP的哺乳动物FTZ-F1基因在肾上腺皮质细胞中的转录调节的两种机制：顺式元件的关键作用，小鼠和大鼠FTZ-F1基因的类固醇生成细胞特异性表达的E盒，rFTZ-F1基因可能通过与第一内含子中的Ad 4（或SF-1）位点结合而被Ad 4 BP自身调控。本研究从上述两个方面探讨了FTZ-F1基因在肾上腺皮质细胞中的转录调控机制。通过对hFTZ-F1基因5 '侧翼区的一系列缺失分析和瞬时转染研究的定点突变，还发现在转录起始位点-87/-82处的E盒元件CACGTG对于hFTZ-F1基因在小鼠或人肾上腺皮质细胞系以及非类固醇生成CV-1细胞中的转录是必需的。尽管在hFTZ-F1基因的第一内含子中存在相应的Ad 4位点CCAAGGCC，但发现通过Ad 4位点的自动调节机制在hFTZ-F1基因中不太可能，主要是由于定点诱变。此外，Ad 4 BP的强制表达对非类固醇生成CV-1细胞中hFTZ-F1基因的转录几乎没有影响。hFTZ-F1基因的这种Ad 4 BP非依赖性调节与类固醇生成性β-内酰胺酶基因（如人CYP 11 A基因）的调节形成鲜明对比，其中近端启动子活性是Ad 4 BP依赖性的，并且Ad 4 BP的反式激活被DAX-1沉默。尽管已经报道了DAX-1基因的Ad 4 BP依赖性转录调控，但在我们的研究中DAX-1并不影响hFTZ-F1基因的转录活性。综上所述，这些观察结果表明，E盒确实是必需的FTZ-F1基因的表达，至少在哺乳动物物种中，但可能不确定的组织特异性表达的hFTZ-F1基因，而且，不像类固醇激素合成β-内酰胺酶基因，调节hFTZ-F1基因似乎是独立的Ad 4 BP和DAX-1。
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.