Department of Internal Medicine, Division of Nephrology, Ewha Medical Research Center, School of Medicine, Ewha Womans University, Seoul, Republic of Korea.
Department of Life Sciences, Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul, Republic of Korea.
Lab Invest. 2015 Oct;95(10):1157-73. doi: 10.1038/labinvest.2015.91. Epub 2015 Jul 20.
Epithelial-to-mesenchymal transition (EMT) and apoptosis of peritoneal mesothelial cells are known to be the earliest mechanisms of peritoneal fibrosis in peritoneal dialysis (PD). Endoplasmic reticulum (ER) stress with an unfolded protein response is regarded to have a role in the development of organ fibrosis. To investigate the potential role of ER stress as a target to prevent and/or delay the development of peritoneal fibrosis, we examined the effect of ER stress on EMT or apoptosis of human peritoneal mesothelial cells (HPMCs) and elucidated the mechanisms underlying the protective effect of ER stress preconditioning on TGF-β1-induced EMT. ER stress inducers, tunicamycin (TM) and thapsigargin (TG), induced EMT with Smad2/3 phosphorylation, an increased nuclear translocation of β-catenin and Snail expression. Low concentrations of TM and TG did not induce apoptosis within 48 h; however, high concentrations of TM- (>1 ng/ml) and TG- (>1 nM) induced apoptosis at 12 h with a persistent increase in C/EBP homologous protein. TGF-β1 induced EMT and apoptosis in HPMCs, which was ameliorated by taurine-conjugated ursodeoxycholic acid, an ER stress blocker. Interestingly, pre-treatment with TM or TG for 4 h also protected the cells from TGF-β1-induced EMT and apoptosis, demonstrating the role of ER stress as an adaptive response to protect HPMCs from EMT and apoptosis. Peritoneal mesothelial cells isolated from PD patients displayed an increase in GRP78/94, which was correlated with the degree of EMT. These findings suggest that the modulation of ER stress in HPMCs could serve as a novel approach to ameliorate peritoneal damage in PD patients.
上皮-间充质转化（EMT）和腹膜间皮细胞凋亡已知是腹膜透析（PD）中腹膜纤维化的最早机制。内质网（ER）应激伴未折叠蛋白反应被认为在器官纤维化的发展中起作用。为了研究 ER 应激作为预防和/或延迟腹膜纤维化发展的靶点的潜在作用，我们研究了 ER 应激对人腹膜间皮细胞（HPMCs）的 EMT 或凋亡的影响，并阐明了 ER 应激预处理对 TGF-β1 诱导的 EMT 的保护作用的机制。ER 应激诱导剂，衣霉素（TM）和他普西龙（TG），诱导 EMT 伴随着 Smad2/3 磷酸化、β-连环蛋白核易位增加和 Snail 表达增加。低浓度的 TM 和 TG 在 48 小时内不会诱导凋亡；然而，高浓度的 TM（>1ng/ml）和 TG（>1nM）在 12 小时内诱导凋亡，C/EBP 同源蛋白持续增加。TGF-β1 在 HPMCs 中诱导 EMT 和凋亡，这被 ER 应激阻断剂牛磺酸结合熊去氧胆酸所改善。有趣的是，TM 或 TG 预处理 4 小时也能保护细胞免受 TGF-β1 诱导的 EMT 和凋亡，表明 ER 应激作为一种适应性反应，保护 HPMCs 免受 EMT 和凋亡。从 PD 患者分离的腹膜间皮细胞显示 GRP78/94 增加，这与 EMT 的程度相关。这些发现表明，HPMCs 中 ER 应激的调节可能成为改善 PD 患者腹膜损伤的新方法。
