Department of Obstetrics and Gynecology, Women and Children's Health Research Institute (WCHRI), Cardiovascular Research Centre and Mazankowski Alberta Heart Institute, University of Alberta, 232 HMRC, Edmonton, AB, Canada.
Cardiovasc Res. 2010 Mar 1;85(4):796-805. doi: 10.1093/cvr/cvp368. Epub 2009 Nov 13.
Estrogen induces nitric oxide (NO) in the endothelium and appears to protect against inflammation and atherosclerosis. NO can induce post-translational protein modifications such as cysteine S-nitrosylation in the cellular proteins which may exert anti-inflammatory effects. However, whether estrogen can induce protein S-nitrosylation in the endothelium is not known. Given this background, we investigated the role of 17beta-estradiol (E2beta), the major form of estrogen in the body, on endothelial protein S-nitrosylation.
Experiments were performed in human umbilical vein endothelial cells (HUVECs). S-nitrosylation was detected by immunostaining for nitrosocysteine and further confirmed by biotin switch method. Ovariectomized 12-month-old Sprague-Dawley rats with/without estradiol supplementation were used for in vivo validation of findings. We found that physiologically relevant doses of E2beta increased protein S-nitrosylation in HUVECs through estrogen receptor-alpha (ERalpha) and endothelial nitric oxide synthase (eNOS). Interestingly, specific agonists for both ERalpha and ERbeta increased eNOS protein expression, while only the former could activate eNOS through phosphorylation. S-nitrosylation by E2beta prevented angiotensin II-induced upregulation of intercellular cell adhesion molecule-1, suggesting a potential anti-inflammatory mechanism. Finally, we showed that exogenous E2beta could increase endothelial S-nitrosylation in vivo in a rat model.
Our results demonstrate for the first time that E2beta increases protein S-nitrosylation in the vascular endothelium, which might be a novel pathway to mediate the protective effects on the vasculature.
雌激素可诱导血管内皮细胞产生一氧化氮（NO），并可能预防炎症和动脉粥样硬化。NO 可诱导细胞蛋白的翻译后蛋白修饰，如半胱氨酸 S-亚硝基化，从而发挥抗炎作用。然而，雌激素是否能诱导内皮细胞的蛋白 S-亚硝基化尚不清楚。鉴于此，我们研究了内源性雌激素 17β-雌二醇（E2β）在血管内皮蛋白 S-亚硝基化中的作用。
在人脐静脉内皮细胞（HUVEC）中进行实验。通过免疫染色检测亚硝基半胱氨酸来检测 S-亚硝基化，并通过生物素转换法进一步确认。用 12 个月大的去卵巢 Sprague-Dawley 大鼠（有/无雌激素补充）进行体内验证。我们发现，生理相关剂量的 E2β 通过雌激素受体-α（ERα）和内皮型一氧化氮合酶（eNOS）增加 HUVEC 中的蛋白 S-亚硝基化。有趣的是，ERα 和 ERβ 的特异性激动剂均可增加 eNOS 蛋白表达，但只有前者可通过磷酸化激活 eNOS。E2β 的 S-亚硝基化可防止血管紧张素 II 诱导的细胞间黏附分子-1 的上调，提示其具有潜在的抗炎机制。最后，我们表明外源性 E2β 可在大鼠模型中增加血管内皮的 S-亚硝基化。
我们的研究结果首次表明，E2β 可增加血管内皮细胞的蛋白 S-亚硝基化，这可能是介导其对血管保护作用的新途径。
