Smith Layton Harris, Coats Stephen R, Qin Hao, Petrie Matthew S, Covington Joseph W, Su Ming, Eren Mesut, Vaughan Douglas E
Department of Medicine, Vanderbilt University Medical Center and Nashville Veterans Affairs Medical Center, Nashville, Tenn 37232-6300, USA.
Circ Res. 2004 Aug 6;95(3):269-75. doi: 10.1161/01.RES.0000136521.70093.f1. Epub 2004 Jun 24.
To investigate the molecular mechanisms involved in the estrogen-dependent control of plasminogen activator inhibitor-1 (PAI-1) gene expression in vascular cells, we compared the transactivation properties of estrogen receptors (ERalpha and ERbeta) in regulating the activity of a human PAI-1 promoter reporter construct in transfected bovine aortic endothelial cells (BAECs). ERalpha increased PAI-1 promoter activity in BAECs by an estrogen-dependent mechanism, whereas ERbeta suppressed PAI-1 promoter activity by an estrogen-independent mechanism. The suppressive activity of ERbeta was dominant over the inductive activity of ERalpha. Mutation of a putative estrogen response element (ERE) located at position -427 in the proximal promoter abolished the ERalpha action without influencing the suppressive effects of ERbeta. Mutation of either AP1-like site did not eliminate the ERalpha or ERbeta actions at the PAI-1 promoter, suggesting that other promoter elements are involved in these responses. These mutations significantly reduced the -3.4kbp PAI-1 promoter response to serum. We concluded that ERalpha and ERbeta exert differential effects on the PAI-1 promoter activity in transfected BAECs. ERalpha activated the PAI-1 promoter through a proximal ERE (-427) and possibly additional EREs located within the PAI-1 promoter, whereas ERbeta suppressed the promoter construct via an unidentified mechanism. This is the first demonstration of the differential regulation of a vascular gene promoter by ERalpha and ERbeta.
为了研究血管细胞中纤溶酶原激活物抑制剂-1（PAI-1）基因表达的雌激素依赖性调控所涉及的分子机制，我们比较了雌激素受体（ERα和ERβ）在转染的牛主动脉内皮细胞（BAECs）中调节人PAI-1启动子报告基因构建体活性的反式激活特性。ERα通过雌激素依赖性机制增加BAECs中PAI-1启动子活性，而ERβ通过雌激素非依赖性机制抑制PAI-1启动子活性。ERβ的抑制活性强于ERα的诱导活性。位于近端启动子-427位的假定雌激素反应元件（ERE）发生突变消除了ERα的作用，而不影响ERβ的抑制作用。任一AP1样位点发生突变均未消除ERα或ERβ在PAI-1启动子上的作用，提示其他启动子元件参与了这些反应。这些突变显著降低了-3.4kbp PAI-1启动子对血清的反应。我们得出结论，ERα和ERβ对转染的BAECs中PAI-1启动子活性具有不同的影响。ERα通过近端ERE（-427）以及可能位于PAI-1启动子内的其他ERE激活PAI-1启动子，而ERβ通过未知机制抑制启动子构建体。这是首次证明ERα和ERβ对血管基因启动子的差异调节。
