Concentrations of 2-methoxyestradiol (2ME2), a principal metabolite of estradiol, are significantly lower in women with severe preeclampsia. Nitric oxide (NO) released by endothelial nitric oxide synthase (eNOS) plays an important role in regulating cardiovascular homeostasis. Importantly, high-density lipoprotein (HDL) stimulates eNOS activity via endothelial human scavenger receptor class B type I (hSR-BI/CLA-1). Here, we aimed to determine the effect of 2ME2 on hSR-BI/CLA-1 expression in human umbilical vein endothelial cells (HUVECs). hSR-BI/CLA-1 expression was measured by real-time PCR, western blotting and reporter gene assays; eNOS activity was assessed by the measurement of eNOS phosphorylation. Both the mRNA and protein concentrations of hSR-BI/CLA-1 were significantly increased by 2ME2 in HUVECs. 2ME2 also dose-dependently increased the transcriptional activity of the hSR-BI/CLA-1 promoter. The effect of 2ME2 treatment on the promoter activity of hSR-BI/CLA-1 was abrogated by treatment with LY294002, a specific inhibitor of phosphatidylinositol 3-kinase, as was the increase in HDL-induced eNOS activation. Notably, constitutively active Akt increased the activity of the hSR-BI/CLA-1 promoter, whereas dominant-negative Akt abolished the effect of 2ME2 treatment on hSR-BI/CLA-1 promoter activity. The nuclear Sp1 protein concentration was significantly increased by exposure to 2ME2 and Sp1 overexpression increased the promoter activity of the hSR-BI/CLA gene. Furthermore, knockdown of Sp1 inhibited the effect of 2ME2 treatment on hSR-BI/CLA-1 protein expression. These results indicate that 2ME2 treatment increases HDL-dependent eNOS phosphorylation by upregulating endothelial hSR-BI/CLA-1 expression, suggesting that 2ME2 has a potential therapeutic value in the treatment of preeclampsia.

中文翻译：

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用 2-甲氧基雌二醇治疗通过人脐静脉内皮细胞中的 BI 类清道夫受体增加内皮一氧化氮合酶活性。

严重先兆子痫女性的雌二醇主要代谢物 2-甲氧基雌二醇 (2ME2) 的浓度显着降低。由内皮一氧化氮合酶 (eNOS) 释放的一氧化氮 (NO) 在调节心血管稳态中起重要作用。重要的是，高密度脂蛋白 (HDL) 通过内皮人类清道夫受体 B 类 I (hSR-BI/CLA-1) 刺激 eNOS 活性。在这里，我们旨在确定 2ME2 对人脐静脉内皮细胞 (HUVEC) 中 hSR-BI/CLA-1 表达的影响。hSR-BI/CLA-1 表达通过实时 PCR、蛋白质印迹和报告基因检测进行测量；通过测量 eNOS 磷酸化来评估 eNOS 活性。HUVEC 中 hSR-BI/CLA-1 的 mRNA 和蛋白质浓度均通过 2ME2 显着增加。2ME2 还剂量依赖性地增加了 hSR-BI/CLA-1 启动子的转录活性。2ME2 处理对 hSR-BI/CLA-1 启动子活性的影响被 LY294002（一种磷脂酰肌醇 3-激酶的特异性抑制剂）处理取消，HDL 诱导的 eNOS 激活增加也是如此。值得注意的是，组成型活性 Akt 增加了 hSR-BI/CLA-1 启动子的活性，而显性失活 Akt 消除了 2ME2 处理对 hSR-BI/CLA-1 启动子活性的影响。暴露于 2ME2 后核 Sp1 蛋白浓度显着增加，Sp1 过表达增加了 hSR-BI/CLA 基因的启动子活性。此外，Sp1 的敲低抑制了 2ME2 处理对 hSR-BI/CLA-1 蛋白表达的影响。