Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cereb...Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.展开更多
目的探讨香砂六君子汤对脾虚高脂血症大鼠内质网应激蛋白激酶R样内质网激酶(protein kinase R-like ER kinase,PERK)信号通路的影响。方法SD大鼠随机分为4组,即正常对照组、脾虚高脂组、香砂六君子汤组和辛伐他汀组,后3组采用饮食不节...目的探讨香砂六君子汤对脾虚高脂血症大鼠内质网应激蛋白激酶R样内质网激酶(protein kinase R-like ER kinase,PERK)信号通路的影响。方法SD大鼠随机分为4组,即正常对照组、脾虚高脂组、香砂六君子汤组和辛伐他汀组,后3组采用饮食不节加力竭游泳的复合方法造模15 d后,正常组喂饲基础饲料,其余3组喂饲高脂饲料。12周后,分别给予相对剂量药物和生理盐水。4周后,检测各组大鼠血脂含量、D-木糖排泄率,油红O染色观察肝脏脂质沉积情况,实时荧光定量PCR及Western blot法检测大鼠肝脏葡萄糖调节蛋白78(glucose regulated protein 78 kD,GRP78)、PERK和活化转录因子4(the activating transcription factor 6,ATF4)基因及蛋白表达。结果与正常对照组比较,脾虚高脂组大鼠血清脂质异常,表现为总胆固醇(cholesterol,TC)、甘油三酯(triglyceride,TG)、低密度脂蛋白胆固醇酯(low density lipoprotein-cholesterol,LDL-C)明显升高,高密度脂蛋白胆固醇酯(high density lipoprotein-cholesterol,HDL-C)明显降低,尿D-木糖排泄率明显降低;肝脏脂质沉积显著,可见明显脂滴;肝脏GRP78、PERK和ATF4 mRNA水平及蛋白表达水平显著升高。与脾虚高脂组比较,香砂六君子汤组和辛伐他汀组大鼠血清TC、TG、LDL-C明显降低,HDL-C明显升高,尿D-木糖排泄率明显升高;其肝脏脂质沉积情况有明显改善,脂滴不同程度减轻;肝脏GRP78、PERK和ATF4 mRNA水平及蛋白表达水平明显降低。结论香砂六君子汤可能通过调控内网应激PERK信号通路来纠正脾虚脂质紊乱的状态。展开更多
未折叠蛋白在内质网(endoplasmic reticulum,ER)腔中累积造成ER应激,此时细胞启动未折叠蛋白响应(unfolded protein response,UPR)以恢复蛋白质稳态。目前已知有三种UPR感受器,即IRE1、PERK和ATF6,它们均为ER跨膜蛋白,在ER应激时被激活...未折叠蛋白在内质网(endoplasmic reticulum,ER)腔中累积造成ER应激,此时细胞启动未折叠蛋白响应(unfolded protein response,UPR)以恢复蛋白质稳态。目前已知有三种UPR感受器,即IRE1、PERK和ATF6,它们均为ER跨膜蛋白,在ER应激时被激活并启动下游UPR信号通路。虽然UPR感受器最早是在研究细胞如何应对ER应激时发现的,但它们如何感知ER应激至今未得到完满的回答。随着研究的深入,人们发现UPR的功能不仅限于维持蛋白质稳态,而UPR感受器也不是只对未折叠蛋白累积作出响应。本文对UPR的发现及其经典通路作一介绍,着重阐述目前已知的UPR感受器的激活机制,并就UPR和ER应激关系以及该领域存在的问题进行讨论。展开更多
基金supported by the National Natural Science Foundation of China,Nos.82260245(to YX),81660207(to YX),81960253(to YL),82160268(to YL),U1812403(to ZG)Science and Technology Projects of Guizhou Province,Nos.[2019]1440(to YX),[2020]1Z067(to WH)+1 种基金Cultivation Foundation of Guizhou Medical University,No.[20NSP069](to YX)Excellent Young Talents Plan of Guizhou Medical University,No.(2022)101(to WH)。
文摘Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.
文摘未折叠蛋白在内质网(endoplasmic reticulum,ER)腔中累积造成ER应激,此时细胞启动未折叠蛋白响应(unfolded protein response,UPR)以恢复蛋白质稳态。目前已知有三种UPR感受器,即IRE1、PERK和ATF6,它们均为ER跨膜蛋白,在ER应激时被激活并启动下游UPR信号通路。虽然UPR感受器最早是在研究细胞如何应对ER应激时发现的,但它们如何感知ER应激至今未得到完满的回答。随着研究的深入,人们发现UPR的功能不仅限于维持蛋白质稳态,而UPR感受器也不是只对未折叠蛋白累积作出响应。本文对UPR的发现及其经典通路作一介绍,着重阐述目前已知的UPR感受器的激活机制,并就UPR和ER应激关系以及该领域存在的问题进行讨论。
