抑制内质网相关降解途径引起大鼠肝细胞内质网应激和自噬增强

Suppression against ERAD pathway induced ERS and autophagy enhancement in rat hepatocytes

目的:探讨内质网相关降解途径(endoplasmic reticulum-associated degradation,ERAD)抑制对静息大鼠肝细胞自噬变化和内质网应激(endoplasmic reticulum stress,ERS)的影响。方法:培养的大鼠肝细胞株BRL用ERAD抑制剂EeyarestatinⅠ(EerⅠ)或b-AP15处理细胞12 h,用等体积的溶剂PBS作对照。用蛋白印迹技术检测ERS及其下游信号系统非折叠蛋白反应(unfolded protein response,UPR)、细胞凋亡及自噬相关蛋白的表达变化,用CCK-8方法检测细胞活力。结果:与对照组比较,EerⅠ或b-AP15能剂量依赖性引起大鼠肝细胞自噬标志性蛋白beclin1、LC3-Ⅱ表达显著上调和LC3-Ⅱ/Ⅰ明显增高,ERS标志性蛋白GRP78、caspase-12和CHOP表达明显上调以及UPR相关蛋白p-IRE1α和XBP-1S表达上调,细胞凋亡激活型caspase-3及其底物PARP-1裂解片段89 ku表达明显增加及细胞活力明显降低。结论:抑制ERAD通路可引起静息的大鼠肝细胞ERS和自噬增强。

Objective： To investigate the changes of endoplasmic reticulum stress（ERS） and autophagy induced by suppre- ssion against endoplasmic reticulum-associated degradation（ERAD） pathway in rest hepatocytes of rat. Methods： Rat hepatocyte line BRL cells were treated with different doses of ERAD inhibitor Eeyarestatin I （Eer I ） or b-AP15 for 12 h, the vehicle PBS was used as control simultaneously.Western Blot assay was employed to detect the protein expression of autophagy-related proteins, ERS/UPR-related proteins, apoptosis-related proteins. Cell-counting kit-8（CCK-8） was performed to evaluate cell viability. Results： Compared with the control group, Eer I or b-AP15, in a dose-dependent manner,induced significant up- regulation of ERS-related proteins such as GRP78, CHOP and caspase-12 and UPR-related proteins p-IRE1α and XBP-1S, remarked expression of autophagy-related proteins LC3- II , Beclin 1 as well as increased ratio of LC3-II/I , apoptosis executioner proteins caspase-3 expression upregulation and its substrate molecule cleaved PARP-1 89 ku fragment increase, and decreased cell viability of rat heptoeytes. Conclusion： Suppression against ERAD pathway induced autophagy enhance- ment and ERS in quiescent hepatocytes of rat.