Institute of Toxicology, College of Medicine, National Taiwan University, Taipei 10051, Taiwan.
Toxicol Sci. 2010 Apr;114(2):295-301. doi: 10.1093/toxsci/kfq006. Epub 2010 Jan 13.
Contrast medium (CM) induces a direct toxic effect on renal tubular cells. This toxic effect may have a role in the pathophysiology of CM-induced nephropathy. CM has been shown to affect the endoplasmic reticulum (ER)-related capacity. Unfolded protein response (UPR) is known as a prosurvival response to reduce the accumulation of unfolded proteins and restore normal ER function. However, the role of ER stress-related UPR in the CM-induced renal cell injury still remains unclear. In this study, we examined whether UPR participates in urografin (an ionic CM)-induced renal tubular cells apoptosis. Treatment with urografin in normal rat renal tubular cell line (NRK52E) markedly increased cell apoptosis and decreased cell viability with a dose- and time-dependent manner. The cell necrosis was not increased in urografin-treated cells. Urografin also enhance the induction of ER stress-related markers in NRK52E cells, including glucose-regulated protein (GRP)78 and GRP94 expressions, procaspase-12 cleavage, phosphorylation of PERK (PKR [double-stranded RNA-activated protein kinase]-like ER kinase), and eukaryotic initiation factor 2alpha (eIF2alpha). Salubrinal, a selective inhibitor of eIF2alpha dephosphorylation, effectively decreased urografin-induced cell apoptosis. Furthermore, transfection of GRP78-small interfering RNA in NRK52E cells significantly enhanced urografin-induced cell apoptosis. These results suggest that GRP78/eIF2alpha-related signals play a protective role during UPR, and the activation of ER stress-related UPR may play an important regulative role in urografin-induced renal tubular injury.
对比剂（CM）对肾小管细胞有直接的毒性作用。这种毒性作用可能在 CM 诱导的肾病的病理生理学中起作用。已经表明 CM 会影响内质网（ER）相关能力。未折叠蛋白反应（UPR）是一种已知的生存反应，可减少未折叠蛋白的积累并恢复 ER 功能正常。然而，ER 应激相关 UPR 在 CM 诱导的肾小管细胞损伤中的作用仍不清楚。在这项研究中，我们研究了 UPR 是否参与泛影葡胺（一种离子型 CM）诱导的肾小管细胞凋亡。用泛影葡胺处理正常大鼠肾小管细胞系（NRK52E）时，细胞凋亡明显增加，细胞活力呈剂量和时间依赖性下降。细胞坏死在泛影葡胺处理的细胞中并未增加。泛影葡胺还增强了 NRK52E 细胞中 ER 应激相关标志物的诱导，包括葡萄糖调节蛋白（GRP）78 和 GRP94 的表达、前半胱氨酸酶-12 的切割、PKR（双链 RNA 激活蛋白激酶样 ER 激酶）的磷酸化和真核起始因子 2alpha（eIF2alpha）。Salubrinal，一种 eIF2alpha 去磷酸化的选择性抑制剂，可有效降低泛影葡胺诱导的细胞凋亡。此外，在 NRK52E 细胞中转染 GRP78 小干扰 RNA 可显著增强泛影葡胺诱导的细胞凋亡。这些结果表明，GRP78/eIF2alpha 相关信号在 UPR 中起保护作用，而 ER 应激相关 UPR 的激活可能在泛影葡胺诱导的肾小管损伤中起重要的调节作用。
