Objective To investigate the role of Taraxasterol(TAR)on ferroptosis in chondrocytes induced by Erastin.Methods The C28/I2 chondrocyte line was treated with Erastin to construct the ferroptosis model of chon-drocytes in vitro and the experiments were divided into Control,Erastin,TAR,and TAR+Erastin groups.Cell via-bility was detected by the CCK-8 assay.Cytotoxicity was detected by the lactate dehydrogenase(LDH)kit and the Calcein/PI cytokinesis kit.Flow cytometry was used to detect lipid reactive oxygen species(ROS).The intracellular glutathione(GSH)content was detected by GSH kit.Mitochondrial membrane potential was detected by JC-1 stai-ning and RH123 staining.ACSL4 and GPX4 protein expression and the key indicators of ferroptosis were detected by Western blot.Results TAR restored the decreased cell viability of C28/I2 chondrocytes induced by Erastin treatment as well as reduced Erastin-induced cytotoxicity(P＜0.01).Compared with the control group,the level of intracellular lipid ROS increased(P＜0.01)and the content of GSH decreased(P＜0.01)after treatment with Erastin,while TAR could reduce the production of lipid ROS(P＜0.01)and increase the content of GSH(P＜0.01).TAR restored mitochondrial membrane potential in C28/I2 chondrocytes ferroptosis,decreased ACSL4 pro-tein expression(P＜0.01)and increased GPX4 protein expression(P＜0.01).In addition,TAR restored the re-duced cell viability caused by IL-1 β treatment.Conclusion TAR can inhibit Erastin induced ferroptosis in C28/I2 chondrocytes,which may be related to the regulation of ACSL4 and GPX4 protein expression.

Objective To explore the effect of 2-aminoethoxy-diphenyl borate(2-APB)on H2O2-induced chondro-cyte apoptosis and its mechanism.Methods The experiment was divided into control group,H2O2 group,2-APB group and H2O2+2-APB group.CCK-8 method was used to detect the cell viability of each group;The effect of 2-APB on the morphological changes of chondrocytes induced by H2O2 was observed under microscopy;TUNEL meth-od and flow cytometry were used to detect chondrocyte apoptosis;Flow cytometry was used to detect Lipid reactive oxygen species(ROS);Western blot was used to detect the protein expressions of Cleaved-PARP,p-PKCα and HIF-1α in H2O2-induced cells by 2-APB;Immunofluorescence was used to detect the fluorescent expression of HIF-1α in cells induced by H2O2 by PKCα inhibitor BIM-1.Results 2-APB inhibited H2O2-induced apoptosis in chon-drocytes,and the inhibitory effect was the most significant when the concentration of 2-APB was 100 pmol/L(F=235.80,P＜0.01);22-APB could inhibit the positive rate of H2O2-induced apoptosis of chondrocytes(F=114.80,P＜0.01)and the level of ROS(F=52.99,P＜0.01).and inhibited the expression of Cleaved-PARP(F=10.10,P＜0.05),p-PKCα(F=24.56,P＜0.05)and HIF-1α proteins(F=6.85,P＜0.05).The PKCα in-hibitor BIM-Ⅰ could inhibit the increase in HIF-1α fluorescence intensity caused by H2O2.Conclusion 2-APB can inhibit chondrocytes apoptosis induced by H2O2 through the PKCα/HIF-1α pathway and thus protect chondro-cytes.

AIM:To investigate the effect of Cara-gana sinica root(CSR)on ferroptosis in the Erastin-induced chondrocyte ferroptosis model and possi-ble mechanisms.METHODS:The C28/I2 chondro-cyte cell line was cultured to construct a cell model of Erastin-induced ferroptosis.Cell viability was de-tected by MTT assay;cell death was observed by Calcein/PI staining;cell lactate dehydrogenase(LDH)and total glutathione(GSH)levels were de-tected by the kit;reactive oxygen species(ROS)lev-els were detected by fluorescent probe BODIPY 581/591 C11 labeling;mitochondrial membrane po-tential(ΔΨm)changes were observed by Rh123 and JC-1 staining;Western blot was used to detect the expression of ferroptosis-related proteins(AC-SL4,GPX4)and TRPM7 proteins.RESULTS:Erastin treatment decreased chondrocyte viability,in-creased cytotoxicity,induced oxidative stress,dis-rupted ΔΨm,and up-regulated ACSL4 protein ex-pression,while down-regulating GPX4 protein ex-pression and inducing chondrocyte ferroptosis.In contrast,CSR restored cell viability and reduced oxi-dative stress,thereby inhibiting chondrocyte fer-roptosis.In addition,CSR reduced the Erastin-in-duced increase in TRPM7 protein expression level.CONCLUSION:Erastin induced lipid peroxidation in C28/I2 chondrocytes,causing mitochondrial dam-age and ferroptosis;CSR may inhibit chondrocyte ferroptosis by blocking TRPM7,thus exerting a pro-tective effect on chondrocytes.