Hong Hong-Jye, Liu Ju-Chi, Chan Paul, Juan Shu-Hui, Loh Shih-Hurng, Lin Jaung-Geng, Cheng Tzu-Hurng
School of Chinese Medicine, China Medical University, Taichung, Taiwan, ROC.
J Biomed Sci. 2004 Jan-Feb;11(1):27-36. doi: 10.1007/BF02256546.
It is well documented that 17beta-estradiol (E(2)) exerts a cardiovascular protective effect. A possible role of E(2) in the regulation of endothelin-1 (ET-1) production has been reported. However, the complex mechanisms by which E(2) inhibits ET-1 expression are not completely understood. The aims of this study were to examine whether E(2) may alter angiotensin II (Ang II)-induced cell proliferation and ET-1 gene expression and to identify the putative underlying signaling pathways in rat aortic smooth muscle cells. Cultured rat aortic smooth muscle cells were preincubated with E(2), then stimulated with Ang II, and [(3)H]thymidine incorporation and ET-1 gene expression were examined. The effect of E(2) on Ang-II-induced extracellular signal-regulated kinase (ERK) phosphorylation was tested to elucidate the intracellular mechanism of E(2) in proliferation and ET-1 gene expression. Ang II increased DNA synthesis which was inhibited with E(2) (1- 100 nM). E(2), but not 17alpha-estradiol, inhibited the Ang-II-induced ET-1 gene expression as revealed by Northern blotting and promoter activity assay. This effect was prevented by coincubation with the estrogen receptor antagonist ICI 182,780 (1 microM). E(2) also inhibited Ang-II-increased intracellular reactive oxygen species (ROS) as measured by a redox-sensitive fluorescent dye, 2',7'-dichlorofluorescin diacetate, and ERK phosphorylation. Furthermore, E(2) and antioxidants, such as N-acetyl cysteine and diphenylene iodonium, decreased Ang-II-induced cell proliferation, ET-1 promoter activity, ET-1 mRNA, ERK phosphorylation, and activator protein-1-mediated reporter activity. In summary, our results suggest that E(2) inhibits Ang-II-induced cell proliferation and ET-1 gene expression, partially by interfering with the ERK pathway via attenuation of ROS generation. Thus, this study provides important new insight regarding the molecular pathways that may contribute to the proposed beneficial effects of estrogen on the cardiovascular system.
有充分文献记载，17β-雌二醇（E₂）具有心血管保护作用。已有报道称E₂在调节内皮素-1（ET-1）生成中可能发挥作用。然而，E₂抑制ET-1表达的复杂机制尚未完全明确。本研究的目的是检测E₂是否会改变血管紧张素II（Ang II）诱导的细胞增殖和ET-1基因表达，并确定大鼠主动脉平滑肌细胞中潜在的信号传导途径。将培养的大鼠主动脉平滑肌细胞先用E₂预孵育，然后用Ang II刺激，检测[³H]胸腺嘧啶核苷掺入及ET-1基因表达情况。检测E₂对Ang II诱导的细胞外信号调节激酶（ERK）磷酸化的影响，以阐明E₂在增殖和ET-1基因表达中的细胞内机制。Ang II增加了DNA合成，而E₂（1 - 100 nM）可抑制此作用。如Northern印迹和启动子活性分析所示，E₂而非17α-雌二醇可抑制Ang II诱导的ET-1基因表达。与雌激素受体拮抗剂ICI 182,780（1 μM）共同孵育可阻断此效应。通过氧化还原敏感荧光染料2',7'-二氯荧光素二乙酸酯检测发现，E₂还可抑制Ang II诱导的细胞内活性氧（ROS）增加以及ERK磷酸化。此外，E₂与抗氧化剂如N-乙酰半胱氨酸和二苯碘鎓可降低Ang II诱导的细胞增殖、ET-1启动子活性、ET-1 mRNA、ERK磷酸化以及活化蛋白-1介导的报告基因活性。总之，我们的结果表明，E₂部分通过减弱ROS生成干扰ERK途径，从而抑制Ang II诱导的细胞增殖和ET-1基因表达。因此，本研究为雌激素对心血管系统有益作用的潜在分子途径提供了重要的新见解。
