Institut National de la Santé et de la Recherche Médicale, UMR915, Institut du Thorax, Nantes, France.
Arterioscler Thromb Vasc Biol. 2011 Nov;31(11):2634-42. doi: 10.1161/ATVBAHA.111.228304.
Estradiol (E2) mediates numerous beneficial effects assigned to estrogens, but whereas mechanisms have been described at the endothelial level, direct effects on vascular smooth muscle cells (VSMC) are poorly documented. As evidence accumulates regarding the role of RhoA in vascular pathophysiology and the benefit of RhoA-Rho associated protein kinase (Rock) pathway inhibition, we analyzed if E2 could inhibit it in VSMC.
We show that in VSMC, E2 inhibits the RhoA-Rock pathway in a time- and concentration-dependent manner. The inhibition of RhoA-Rock pathway results from E2-induced phosphorylation of the Ser188 of RhoA. Using pharmacological, transfection, and in vitro phosphorylation experiments, we demonstrate that AMP-activated protein kinase subunit alpha 1 (AMPKα1) is activated by estrogen receptor stimulation and catalyzes RhoA phosphorylation induced by E2. Ex vivo, ovariectomy leads to an increase in the amplitude of phenylephrine- or serotonine-induced contractions of aortic rings in wild-type mice but not in AMPKα1-knock-out mice or E2-supplemented animals. These functional effects were correlated with a reduced level of RhoA phosphorylation in the aorta of ovariectomized female, male, and AMPKα1 knock-out mice.
Our work thus defines AMPKα1 as (1) a new kinase for RhoA and (2) a new mediator of the vasoprotective effects of estrogen.
雌二醇（E2）介导了许多被认为与雌激素有关的有益作用，但尽管已经在血管内皮水平上描述了其作用机制，但它对血管平滑肌细胞（VSMC）的直接作用仍鲜有记载。由于越来越多的证据表明 RhoA 在血管病理生理学中的作用以及 RhoA- Rho 相关蛋白激酶（Rock）通路抑制的益处，我们分析了 E2 是否可以在 VSMC 中抑制它。
我们表明，在 VSMC 中，E2 以时间和浓度依赖的方式抑制 RhoA-Rock 通路。RhoA-Rock 通路的抑制是由于 E2 诱导的 RhoA 的 Ser188 磷酸化所致。通过药理学、转染和体外磷酸化实验，我们证明了 AMP 激活的蛋白激酶亚单位α 1（AMPKα1）被雌激素受体刺激激活，并催化 E2 诱导的 RhoA 磷酸化。在体实验中，去卵巢导致野生型小鼠的胸主动脉环对苯肾上腺素或 5-羟色胺诱导的收缩幅度增加，但在 AMPKα1 敲除小鼠或补充 E2 的动物中则没有。这些功能效应与去卵巢雌性、雄性和 AMPKα1 敲除小鼠主动脉中 RhoA 磷酸化水平降低相关。
我们的工作因此将 AMPKα1 定义为（1）RhoA 的一种新激酶和（2）雌激素血管保护作用的新介导物。
