Ding Q, Hussain Y, Chorazyczewski J, Gros R, Feldman R D
Departments of Medicine, Physiology and Pharmacology, Robarts Research Institute, London, Canada.
Departments of Medicine, Physiology and Pharmacology, Robarts Research Institute, London, Canada.
Mol Cell Endocrinol. 2015 Jan 5;399:60-8. doi: 10.1016/j.mce.2014.07.023. Epub 2014 Aug 20.
GPER (aka GPR30) has been identified as an important mechanism by which estrogen mediates its effects. Previous studies from our laboratories and those of others have demonstrated that GPER activation mediates a range of vascular contractile and growth regulatory responses. However, the importance of GPER in mediating the actions of estradiol (E2) in rat aortic endothelial cells is unclear. Therefore, we sought to determine the importance of GPER vs. the "classical" estrogen receptor (ER) in mediating the endothelial growth regulatory effects of E2. To do this we assessed the effect of E2 in regulating phosphoERK content and apoptotic rates in rat aortic endothelial cells and the role of GPER in mediating these effects. E2 mediated a concentration-dependent inhibition of both ERK phosphorylation and serum deprivation-induced apoptosis with a maximal effect at a concentration of 10 nM. Pretreatment with the ER antagonist ICI 182780 abolished E2-mediated inhibition of both ERK phosphorylation and apoptosis. In contrast, pretreatment with GPER antagonist G15 had no significant effect on E2-mediated inhibition of ERK phosphorylation or on apoptosis. Further, downregulation of GPER expression with a GPER shRNA adenovirus did not block E2-mediated inhibitory effects on ERK phosphorylation and apoptosis. In fact, these inhibitory effects of E2 were further enhanced by GPER downregulation. Downregulation of ERα expression reversed the E2-mediated inhibitory effects to stimulatory effects. E2's phosphoERK and apoptosis stimulatory effects seen with ERα downregulation are attenuated by pretreatment with G15. In conclusion, in rat aortic endothelial cells, E2-mediated endothelial effects are predominantly driven by ER and not by GPER.
G蛋白偶联雌激素受体（又称GPR30）已被确定为雌激素发挥其作用的一种重要机制。我们实验室以及其他实验室之前的研究表明，G蛋白偶联雌激素受体的激活介导了一系列血管收缩和生长调节反应。然而，G蛋白偶联雌激素受体在介导雌二醇（E2）对大鼠主动脉内皮细胞作用中的重要性尚不清楚。因此，我们试图确定G蛋白偶联雌激素受体与“经典”雌激素受体（ER）在介导E2的内皮生长调节作用中的重要性。为此，我们评估了E2对大鼠主动脉内皮细胞中磷酸化细胞外信号调节激酶（phosphoERK）含量和凋亡率的调节作用，以及G蛋白偶联雌激素受体在介导这些作用中的作用。E2介导了对ERK磷酸化和血清剥夺诱导的凋亡的浓度依赖性抑制，在浓度为10 nM时具有最大效应。用雌激素受体拮抗剂ICI 182780预处理可消除E2介导的对ERK磷酸化和凋亡的抑制作用。相比之下，用G蛋白偶联雌激素受体拮抗剂G15预处理对E2介导的ERK磷酸化抑制或凋亡没有显著影响。此外，用G蛋白偶联雌激素受体短发夹RNA腺病毒下调G蛋白偶联雌激素受体的表达并没有阻断E2介导的对ERK磷酸化和凋亡的抑制作用。事实上，G蛋白偶联雌激素受体的下调进一步增强了E2的这些抑制作用。雌激素受体α（ERα）表达的下调将E2介导的抑制作用逆转至刺激作用。用G15预处理可减弱ERα下调时E2的磷酸化ERK和凋亡刺激作用。总之，在大鼠主动脉内皮细胞中，E2介导的内皮效应主要由雌激素受体驱动，而非G蛋白偶联雌激素受体。
