Estrogen Receptor-related Receptor α1 Interacts with Coactivator and Constitutively Activates the Estrogen Response Elements of the Human Lactoferrin Gene*
Estrogen Receptor-related Receptor α1 Interacts with Coactivator and Constitutively Activates the Estrogen Response Elements of the Human Lactoferrin Gene*
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DOI：
10.1074/jbc.m001880200
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发表时间：
2000-07
期刊：
影响因子：
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通讯作者：
Zhiping Zhang;C. Teng
中科院分区：
文献类型：
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作者：
Zhiping Zhang;C. Teng
人雌激素受体相关受体（ERRα1，NR 3B 1a）显示与类固醇生成因子结合元件（SFRE）TCAAGGTCATC结合，该元件位于人乳铁蛋白基因启动子的雌激素反应元件（ERE）上游26个碱基对处。在SFRE的突变显着减少雌激素依赖性转录从乳铁蛋白ERE在人类子宫内膜细胞。在这项研究中，我们证明ERRα1结合SFRE和ERE元件，并组成性地反式激活乳铁蛋白基因启动子。DNase I足迹法分析表明，融合蛋白对SFRE和ERE区域均有保护作用。电泳迁移率变动分析表明，该受体与SFRE或ERE均形成两种蛋白质-DNA复合物。哺乳动物双杂交系统证实ERRα1具有同源二聚体。在瞬时转染实验中，ERRα1激活子宫内膜和非子宫内膜细胞中含有各种类型雌激素反应元件的报告基因构建体。过表达辅激活因子SRC 1a或GRIP 1进一步增强ERRα1诱导的转录活性。我们证明ERRα1的AF 2结构域是转录激活功能所必需的，并且该区域的缺失或突变消除了激活能力。通过GST谷胱甘肽S-转移酶“下拉”试验证实了SRC 1a和ERRα1 C末端之间的蛋白质-蛋白质相互作用。当在许多实验中比较ERRα1和雌激素受体α（ERα）时，我们发现ERα也可以结合乳铁蛋白基因的SFRE并以配体依赖性方式反式激活启动子活性。本研究表明ERRα1与ERα结合相似的DNA元件，并组成性地赋予其反式激活功能。因此，ERRα1可能与其他雌激素反应基因一样，对乳铁蛋白基因的雌激素反应具有积极的调节作用。
The human estrogen receptor-related receptor (ERRα1, NR3B1a) was shown to bind a steroidogenic factor binding element (SFRE), TCAAGGTCATC, 26 base pairs upstream from the estrogen response element (ERE) of the human lactoferrin gene promoter. A mutation made at SFRE significantly reduced estrogen-dependent transcription from the lactoferrin ERE in human endometrial cells. In this study, we demonstrated that ERRα1 binds both SFRE and ERE elements and constitutively transactivates the lactoferrin gene promoter. In DNase I footprinting protection analysis, both SFRE and ERE regions were protected by glutathioneS-transferase-ERRα1 fusion protein. The receptor formed two protein-DNA complexes with either SFRE or ERE in electrophoresis mobility shift assay. Homodimerization of ERRα1 was confirmed with the mammalian two-hybrid system. ERRα1 activates reporter constructs containing various types of estrogen response elements in endometrial and non-endometrial cells in transient transfection experiments. Overexpressing the coactivator, SRC1a or GRIP1, further enhances ERRα1-induced transcriptional activity. We demonstrated that the AF2 domain of ERRα1 is essential for the transactivation function and that deletion or mutation at this region abrogates the activation capability. Protein-protein interaction between the SRC1a and ERRα1 C terminus was confirmed with a GST glutathione S-transferase “pull-down” assay. When comparing ERRα1 and the estrogen receptor α (ERα) in many of the experiments, we found that ERα can also bind SFRE of the lactoferrin gene and transactivate the promoter activity in a ligand-dependent manner. The present study demonstrated that ERRα1 binds similar DNA elements as ERα and confers its transactivation function constitutively. Therefore, ERRα1 may actively modulate the estrogen response of lactoferrin gene as well as other estrogen-responsive genes.