State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, China; Shanghai Institute of Pollution Control and Ecological Safety, China.
Division of Cardiology, TongRen Hospital, Shanghai Jiao Tong University School of Medicine, 1111 Xianxia Road, Shanghai 200336, China.
Environ Pollut. 2018 Aug;239:466-472. doi: 10.1016/j.envpol.2018.04.038. Epub 2018 Apr 19.
Our previous study showed that the tea extract, epigallocatechin-3-gallate (EGCG), protects against microcystin-LR (MC-LR) -mediated apoptosis of human umbilical vein endothelial cells (HUVECs); however, the mechanism underlying MC-LR-induced HUVEC apoptosis remains incompletely understood. In this study, we investigated whether the nuclear factor erythroid-like 2 (NRF2)/heme oxygenase-1 (HO-1) pathway, which regulates antioxidant transcriptional regulation of oxidative stress and apoptosis, is involved in this process. Mitochondrial membrane potential (MMP) and caspase-3/-9 activities were evaluated in HUVECs by JC-1 staining and colorimetric activity assay, and a DCFH-DA fluorescent probe assay was used to quantitate reactive oxygen species (ROS) generation. The effects of MC-LR, EGCG, NF2, and HO-1 on HUVEC apoptosis were explored by western blotting and small interfering RNA (siRNA) analyses. MC-LR treatment downregulated HUVEC mitochondrial membrane potential, and decreased levels of cytochrome c release and activated caspase-3/-9, ROS generation, consequently inducing HUVEC apoptosis. EGCG treatment attenuated MC-LR-mediated HUVEC oxidative stress and mitochondria-related apoptosis. EGCG induced NRF2/HO-1 expression and activation in MC-LR treated HUVECs, while downregulation of NRF2/HO-1 by specific siRNAs revealed that NRF2/HO-1 signaling was involved in EGCG attenuation of MC-LR-induced HUVEC apoptosis. Our findings indicate that EGCG treatment protects against MC-LR-mediated HUVEC apoptosis via activation of NRF2/HO-1 signaling.
我们之前的研究表明，茶提取物表没食子儿茶素没食子酸酯（EGCG）可预防微囊藻毒素-LR（MC-LR）介导的人脐静脉内皮细胞（HUVEC）凋亡；然而，MC-LR 诱导的 HUVEC 凋亡的机制仍不完全清楚。在这项研究中，我们研究了核因子红细胞样 2（NRF2）/血红素加氧酶-1（HO-1）途径是否参与了这一过程，该途径调节氧化应激和细胞凋亡的抗氧化转录调节。通过 JC-1 染色和比色法测定，评估 HUVEC 中的线粒体膜电位（MMP）和半胱天冬酶-3/-9 活性，并用 DCFH-DA 荧光探针测定来定量活性氧（ROS）的产生。通过 Western blot 和小干扰 RNA（siRNA）分析研究了 MC-LR、EGCG、NF2 和 HO-1 对 HUVEC 凋亡的影响。MC-LR 处理降低了 HUVEC 线粒体膜电位，减少了细胞色素 c 释放和激活的 caspase-3/-9、ROS 生成，从而诱导 HUVEC 凋亡。EGCG 处理减轻了 MC-LR 介导的 HUVEC 氧化应激和线粒体相关凋亡。EGCG 诱导了 MC-LR 处理的 HUVEC 中 NRF2/HO-1 的表达和激活，而特异性 siRNA 下调 NRF2/HO-1 表明 NRF2/HO-1 信号通路参与了 EGCG 减轻 MC-LR 诱导的 HUVEC 凋亡。我们的研究结果表明，EGCG 通过激活 NRF2/HO-1 信号通路来防止 MC-LR 介导的 HUVEC 凋亡。
