Aim To explore the specific mechanism by which scutellarin(Scu)antagonizes the injury of human aortic endothelial cells(HAEC)induced by 2,2-azobis(2-methylpropylimidate)dihydrochloride(AAPH)by regulating the protein kinase RNA-like endoplasmic reticulum kinase(PERK)-nuclear factor erythroid 2-related factor 2(NRF2)/ac-tivating transcription factor 4(ATF4)-C/EBP homology protein(CHOP)pathway.Methods HAEC were pre-pro-tected by Scu and then injured by AAPH to explore the molecular mechanism of Scu on HAEC injury.The cells were di-vided into control group,AAPH group,AAPH+Scu low,medium and high groups.The contents of superoxide dismutase(SOD),malondialdehyde(MDA),glutathione peroxidase(GSH-Px)and glutathione S-transferase(GSH-ST)in the cells were measured.The content of reactive oxygen species(ROS)in cells was detected by fluorescent probe,and the apop-tosis rate was detected by Annexin V-FITC/PI method.The mRNA expression of PERK and eIF2α in cells was detected by RT-qPCR.The protein expression of glucose regulated protein 78(GRP78),PERK,p-PERK,eukaryotic initiation factor 2α(eIF2α),p-eIF2α,ATF4,CHOP,Nrf2,Bcl-2,p53 up-regulated modulator of apoptosis(PUMA),Caspase-3 and Caspase-12 in cells was detected by Western blot.In order to further study the molecular mechanism of Scu against HAEC injury,gene silencing technology was used to inhibit the expression of PERK in HAEC.The cells were divided in-to five groups:control group,AAPH+si-con group,AAPH+Scu+si-con group,AAPH+si-PERK group,AAPH+si-PERK+Scu group.The mRNA expression of PERK and eIF2α in cells after si-PERK interference was detected by RT-qPCR.The protein expression of PERK,p-eIF2α,eIF2α,ATF4,CHOP,Nrf2,Bcl-2,PUMA,Caspase-3 and Caspase-12 in cells after si-PERK interference was detected by Western blot.Results The content of ROS and the rate of apoptosis were significantly reduced after Scu intervention(P＜0.01).Scu could down-regulate the mRNA expression of PERK and eIF2α,and down-regulate the protein expression of GRP78,p-PERK,p-eIF2α,ATF4,CHOP,PUMA,Caspase-3,Caspase-12 and up-regulate the protein expression of Nrf2 and Bcl-2(P＜0.01).After interference with si-PERK,there were significant differences in the protein expression of PERK,p-eIF2α,ATF4,CHOP,Nrf2,Bcl-2,PUMA,Caspase-3,Caspase-12,as well as the mRNA expression of PERK and eIF2α in cells compared to before interference(P＜0.01).It is proved that Scu could anti-endoplasmic role in reticulum stress and apoptosis,which is closely associated with the regula-tion of the PERK-Nrf2/ATF4-CHOP pathway.Conclusion Scu can effectively alleviate AAPH-induced injury to HAEC by regulating PERK-Nrf2/ATF4-CHOP pathways to inhibit endoplasmic reticulum stress and cell apoptosis.

Aim To explore the specific mechanism by which scutellarin(Scu)antagonizes the injury of human aortic endothelial cells(HAEC)induced by 2,2-azobis(2-methylpropylimidate)dihydrochloride(AAPH)by regulating the protein kinase RNA-like endoplasmic reticulum kinase(PERK)-nuclear factor erythroid 2-related factor 2(NRF2)/ac-tivating transcription factor 4(ATF4)-C/EBP homology protein(CHOP)pathway.Methods HAEC were pre-pro-tected by Scu and then injured by AAPH to explore the molecular mechanism of Scu on HAEC injury.The cells were di-vided into control group,AAPH group,AAPH+Scu low,medium and high groups.The contents of superoxide dismutase(SOD),malondialdehyde(MDA),glutathione peroxidase(GSH-Px)and glutathione S-transferase(GSH-ST)in the cells were measured.The content of reactive oxygen species(ROS)in cells was detected by fluorescent probe,and the apop-tosis rate was detected by Annexin V-FITC/PI method.The mRNA expression of PERK and eIF2α in cells was detected by RT-qPCR.The protein expression of glucose regulated protein 78(GRP78),PERK,p-PERK,eukaryotic initiation factor 2α(eIF2α),p-eIF2α,ATF4,CHOP,Nrf2,Bcl-2,p53 up-regulated modulator of apoptosis(PUMA),Caspase-3 and Caspase-12 in cells was detected by Western blot.In order to further study the molecular mechanism of Scu against HAEC injury,gene silencing technology was used to inhibit the expression of PERK in HAEC.The cells were divided in-to five groups:control group,AAPH+si-con group,AAPH+Scu+si-con group,AAPH+si-PERK group,AAPH+si-PERK+Scu group.The mRNA expression of PERK and eIF2α in cells after si-PERK interference was detected by RT-qPCR.The protein expression of PERK,p-eIF2α,eIF2α,ATF4,CHOP,Nrf2,Bcl-2,PUMA,Caspase-3 and Caspase-12 in cells after si-PERK interference was detected by Western blot.Results The content of ROS and the rate of apoptosis were significantly reduced after Scu intervention(P＜0.01).Scu could down-regulate the mRNA expression of PERK and eIF2α,and down-regulate the protein expression of GRP78,p-PERK,p-eIF2α,ATF4,CHOP,PUMA,Caspase-3,Caspase-12 and up-regulate the protein expression of Nrf2 and Bcl-2(P＜0.01).After interference with si-PERK,there were significant differences in the protein expression of PERK,p-eIF2α,ATF4,CHOP,Nrf2,Bcl-2,PUMA,Caspase-3,Caspase-12,as well as the mRNA expression of PERK and eIF2α in cells compared to before interference(P＜0.01).It is proved that Scu could anti-endoplasmic role in reticulum stress and apoptosis,which is closely associated with the regula-tion of the PERK-Nrf2/ATF4-CHOP pathway.Conclusion Scu can effectively alleviate AAPH-induced injury to HAEC by regulating PERK-Nrf2/ATF4-CHOP pathways to inhibit endoplasmic reticulum stress and cell apoptosis.