School of Life Sciences, Sun Yat-Sen University, Guanghzhou 510275, PR China.
Gen Comp Endocrinol. 2012 Feb 1;175(3):473-87. doi: 10.1016/j.ygcen.2011.12.005. Epub 2011 Dec 14.
Aromatase (CYP19A1) catalyzes the conversion of androgens to estrogens. In teleosts, duplicated copies of cyp19a1 genes, namely cyp19a1a and cyp19a1b, were identified, however, the transcriptional regulation of these two genes remains poorly understood. In the present study, the 5'-flanking regions of the orange-spotted grouper cyp19a1a (gcyp19a1a) and cyp19a1b (gcyp19a1b) genes were isolated and characterized. The proximal promoter regions of both genes were relatively conserved when compared to those of the other teleosts. Notably, a conserved FOXO transcriptional factor binding site was firstly reported in the proximal promoter of gcyp19a1a, and deletion of the region (-112 to -60) containing this site significantly decreased the promoter activities. The deletion of the region (-246 to -112) containing the two conserved FTZ-F1 sites also dramatically decreased the transcriptional activities of gcyp19a1a promoter, and both two FTZ-F1 sites were shown to be stimulatory cis-acting elements. A FTZ-F1 homologue isolated from ricefield eel (eFTZ-F1) up-regulated gcyp19a1a promoter activities possibly via the FTZ-F1 sites, however, a previously identified orange-spotted grouper FTZ-F1 homologue (gFTZ-F1) did not activate the transcription of gcyp19a1a promoter unexpectedly. As to gcyp19a1b promoter, all the deletion constructs did not show good promoter activities in either TM4 or U251-MG cells. Estradiol (100nM) up-regulated gcyp19a1b promoter activities by about 13- and 36-fold in TM4 and U251-MG cells, respectively, via the conserved ERE motif, but did not stimulate gcyp19a1a promoter activities. These results are helpful to further elucidate the regulatory mechanisms of cyp19a1a and cyp19a1b expression in the orange-spotted grouper as well as other teleosts.
芳香酶（CYP19A1）催化雄激素转化为雌激素。在硬骨鱼中，已鉴定出 cyp19a1 基因的两个重复拷贝，即 cyp19a1a 和 cyp19a1b，但这些基因的转录调控仍知之甚少。本研究分离并鉴定了橙色斑点石斑鱼 cyp19a1a（gcyp19a1a）和 cyp19a1b（gcyp19a1b）基因的 5'侧翼区。与其他硬骨鱼相比，这两个基因的近端启动子区相对保守。值得注意的是，首次在 gcyp19a1a 的近端启动子中报道了一个保守的 FOXO 转录因子结合位点，该位点缺失（-112 至-60）显著降低了启动子活性。包含两个保守的 FTZ-F1 位点的区域（-246 至-112）缺失也显著降低了 gcyp19a1a 启动子的转录活性，并且这两个 FTZ-F1 位点都是具有刺激作用的顺式作用元件。从稻田鳗中分离的一个 FTZ-F1 同源物（eFTZ-F1）可能通过 FTZ-F1 位点上调 gcyp19a1a 启动子活性，而之前鉴定的橙色斑点石斑鱼 FTZ-F1 同源物（gFTZ-F1）出人意料地没有激活 gcyp19a1a 启动子的转录。至于 gcyp19a1b 启动子，所有缺失构建体在 TM4 或 U251-MG 细胞中均没有表现出良好的启动子活性。雌二醇（100nM）通过保守的 ERE 基序分别使 TM4 和 U251-MG 细胞中的 gcyp19a1b 启动子活性上调约 13 倍和 36 倍，但没有刺激 gcyp19a1a 启动子活性。这些结果有助于进一步阐明橙色斑点石斑鱼及其他硬骨鱼中 cyp19a1a 和 cyp19a1b 表达的调控机制。
