Endoplasmic reticulum stress(ERS)is closely related to the mechanisms of multiple diseases,and regulation of ERS has become a therapeutic target for several diseases.Previous studies by our group have demonstrated that ERS can be alleviated and neuronal cells can be protected by downregulating ERS-related proteins such as GRP78,caspase12 and caspase3.The research on ERS inhibitors has progressed rapidly in recent years,and they can be classified into various types such as molecular chaperones,small molecule compounds and natural products,such as 4-phenylbutyric acid(4-PBA),tauroursodeoxycholic acid(TUDCA)and tumor necrosis factor α-stimulating factor 6(TSG-6),etc.These inhibitors can regulate the ERS signaling pathway through different pathways,such as:silent information regulator 1(SIRT1)promotes the expression of anti-apop-totic proteins by inhibiting the PERK-eIF2α-ATF4-CHOP pathway,thus reducing apoptosis.In addition,SIRT1 deacetylates XBP-1,regulates the IRE1α-XBP1 signaling pathway,and inhibits the expressions of GRP78 and CHOP,thereby reducing the protein load of endoplasmic reticulum(ER)and alleviating ERS;PDE4 inhibitor regu-lates c-Jun-mediated apoptotic pathway,reduces the interaction between IRE1 and TRAF2,and attenuates the level of c-Jun phosphorylation,thereby restoring ER homeostasis.In addition,PDE4 inhibitor activates the antioxidant-acting Nrf-2 pathway,decreases the concen-tration of intracellular calcium ion and reduces the pro-duction of ROS;TSG-6 exerts anti-inflammatory effects by regulating the secretion of inflammatory factors through PERK-eIF-2α-NF-κB p65 and IRE1α-TRAF2-NF-κB p65 signaling pathways.In-depth exploration of the potential mechanism of action of ERS inhibitors is of great signifi-cance for finding ways to treat related diseases by regu-lating ERS.

OBJECTIVE To investigate the mecha-nism of endoplasmic reticulum stress in cerebral isch-emic stroke from a theoretical perspective based on net-work pharmacology.METHODS GeneCards and OMIM databases were used to screen out the related targets of cerebral ischemic stroke and endoplasmic reticulum stress.And Venny2.1.0 was used to draw Venn's diagram to get the intersecting genes between cerebral ischemic stroke and endoplasmic reticulum stress.String data-base was used to get the protein-protein interaction(PPI)diagram and cytoscape was used for visualization analy-sis.The key genes were screened out by cytohubba plug-in,and enrichment analysis was performed.RESULTS Network pharmacology showed that there were 3744 cerebral ischemic stroke-related targets and 8675 endo-plasmic reticulum stress-related targets.After screening,41 common targets were got.There were 37 nodes,390 edges in the PPI network,namely,there were 37 interact-ing proteins and 390 interacting relationships.The key genes identified by cytohubba plug-in were IL-6,ALB,INS,TNF,AKT1,CASP3,MAPK3,TP53,SIRT1 and VEGF.The biological process involves reaction to oxida-tive stress,the regulation of neuron death,and negative regulation of cell differentiation,etc.;cellular components were related to the membrane raft,smooth endoplasmic reticulum,endoplasmic reticulum lumen and other com-ponents;molecular function aspects were related to sig-naling receptor activator activity,chaperone binding and protease binding.Enrichment analysis of pathway revealed that the intersecting targets were involved in PI3K/Akt pathway and protein processing in endoplasmic reticulum,etc.CONCLUSION The endoplasmic reticu-lum stress in cerebral ischemic stroke is related to the bi-ological processes of reaction to oxidative stress,the reg-ulation of neuron death,and negative regulation of cell differentiation,the mechanism may be related to neuroin-flammation and apoptosis.

During cerebral ischemia-reperfusion injury(CIRI),endoplasmic reticulum stress(ERS)leads to the development and progression of a series of deleterious physiological responses such as oxidative stress,dis-turbed calcium ion homeostasis,inflammation,apoptosis and autophagy.The unfolded protein response(UPR)is the main pathway activated by ERS,which regulates the expression of related factors within the endoplasmic reticu-lum(ER)and reduces protein translation levels.Prolonged and intense ERS may lead to cell death.Excessive ERS induces apoptosis mediated by C/EBP homologous pro-tein(CHOP),caspase-12 and c-Jun N-terminal kinase(JNK),thereby exacerbating brain damage.The thresh-old for the transition from adaptive mechanisms to apop-totic mechanisms during ERS depends on multiple fac-tors,including the cell status and environment,signaling pathway activity status,cumulative cascade,and the dose and time of ERS inducers.Further research is needed to completely elucidate the mechanism of ERS.Although the factors associated with the PERK and ATF6 path-ways are less extensively studied,their regulators still exist.Deficiency of protein tyrosine phosphatase 1B(PTP1B)leads to increased phosphorylation of PERK-eIF2α,while regulation of the proteasome and regulation of the XBP1 target gene WFS1 may also affect ATF6 sta-bility.In addition,differences in the structure,gene expres-sion,and metabolism of different types of neurons,as well as in their internal environment,may lead to differ-ences in their response to and impact on ERS.Differenc-es in UPR signaling pathways occur in hippocampal neurons and medial thalamic cells,and Purkinje cells and pyramidal cells may be more sensitive to ERS than other types of neurons.Our group's previous study found that ERS induced apoptosis in neurons after the onset of CIRI by regulating proteins such as GRP78,CHOP and caspase-12,but the effects of UPR activation on different cells need to be further investigated.