Center for Trophoblast Research, Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom.
Am J Pathol. 2012 Jun;180(6):2309-20. doi: 10.1016/j.ajpath.2012.03.005. Epub 2012 Apr 12.
Recent evidence implicates placental endoplasmic reticulum (ER) stress in the pathophysiological characteristics of preeclampsia. Herein, we investigate whether endothelin (ET)-1, which induces Ca(2+) release from the ER, can induce placental ER stress. Loss of ER Ca(2+) homeostasis impairs post-translational modification of proteins, triggering ER stress-response pathways. IHC confirmed the presence of both ET-1 and its receptors in the syncytiotrophoblast. Protein levels and immunoreactivity of ET-1 and the endothelin B receptor (ETBR) were increased in preeclamptic samples compared with normotensive controls. JEG-3 and BeWo choriocarcinoma cells treated with ET-1 displayed an increase in ER stress markers. ET-1 induced phospho-activation of the ETBR. Treating cells with BQ788, an ETBR antagonist, or small-interfering RNA knockdown of the receptor inhibited induction of ER stress. ET-1 also stimulated p-phospholipase C (PLC)γ1 levels. By using inhibitors of PLC activation, U73122, and the inositol 1,4,5-triphosphate (IP(3)) receptor, xestospongin-C, we demonstrated that ET-1 induces ER stress via the PLC-IP(3) pathway. Furthermore, ET-1 levels increased in the syncytiotrophoblast of explants from normal placentas after hypoxia-reoxygenation in vitro. Conditioned medium from hypoxia-reoxygenation explants also contained higher ET-1 levels, which induced ER stress in JEG-3 cells that was abolished by an ET-1-neutralizing antibody. Collectively, the data show that ET-1 induced ER stress in trophoblasts via the ETBR and initiation of signaling through the PLC-IP(3) pathway, with the potential for autocrine stimulation.
最近的证据表明，胎盘内质网（ER）应激与子痫前期的病理生理特征有关。在此，我们研究了内皮素（ET）-1 是否可以诱导 ER 应激，内皮素（ET）-1 可从 ER 中释放 Ca2+。ER 中 Ca2+ 稳态的丧失会损害蛋白质的翻译后修饰，从而引发 ER 应激反应途径。免疫组化证实 ET-1 及其受体存在于合体滋养层中。与正常血压对照组相比，子痫前期样本中 ET-1 和内皮素 B 受体（ETBR）的蛋白水平和免疫反应性增加。用 ET-1 处理 JEG-3 和 BeWo 绒毛膜癌细胞后，ER 应激标志物增加。ET-1 诱导 ETBR 的磷酸化激活。用 ETBR 拮抗剂 BQ788 或受体的小干扰 RNA 敲低处理细胞可抑制 ER 应激的诱导。ET-1 还刺激 p-磷脂酶 C（PLC）γ1 水平。通过使用 PLC 激活抑制剂 U73122 和肌醇 1,4,5-三磷酸（IP3）受体抑制剂 Xestospongin-C，我们证明 ET-1 通过 PLC-IP3 途径诱导 ER 应激。此外，体外缺氧再复氧后正常胎盘绒毛外植体的合体滋养层中 ET-1 水平增加。缺氧再复氧外植体的条件培养基中也含有更高水平的 ET-1，其可诱导 JEG-3 细胞中的 ER 应激，而 ET-1 中和抗体可消除这种应激。综上所述，这些数据表明，ET-1 通过 ETBR 诱导滋养细胞中的 ER 应激，并通过 PLC-IP3 途径引发信号转导，具有自分泌刺激的潜力。
