Effect of Guilu Erxian (龟鹿二仙) Gel on Endoplasmic Reticulum Homeostasis of Degenerative Chondrocytes in Rats with Knee Osteoarthritis Based on ATF6/GRP78/CHOP Signaling Pathway
Objective:To investigate the effect of Guilu Erxian (龟鹿二仙) Gel on the activation of the transcription factor 6 (ATF6)/glucose reg-ulated protein 78 (GRP78)/C/EBP homologous protein (CHOP) signaling pathway in degenerative chondrocytes induced by thapsigargin (TG) in rats.Methods:Chondrocytes were extracted from rat knee joints and cultured in vitro.Chondrocytes were divided into a blank con-trol group,a model control group,a 10％ Guilu Erxian Gel group,and a 2 μmol/L protein transport protein SX61 (SEC61) inhibitor group.After 24 hours of intervention,the cell activity of each group was detected by CCK-8 method.The expression of SEC61 factor was detected by immunofluorescence staining.Flow cytometry and TUNEL staining were used to detect the apoptosis of chondrocytes in each group,and West-ern blot (WB) and real-time fluorescence-based quantitative polymerase chain reaction (qPCR) were used to detect the expression of ATF6/GRP78/CHOP,type Ⅱ collagen alpha 1 (COL2A1),matrix metalloproteinase-13 (MMP-13) protein and mRNA in chondrocytes of each group.Results:Compared with the blank control group,the cell activity of chondrocytes in the model control group decreased significantly (P<0.01),the apoptosis rate and apoptosis index of chondrocytes increased significantly (P<0.01),SEC61 fluorescence intensity increased sig-nificantly (P<0.01),the expression of GRP78,ATF6,CHOP,COL2A1,MMP-13 protein and mRNA increased (P<0.05).Compared with the model control group,the cell activity of chondrocytes in the 10％ Guilu Erxian Gel group and the 2 μmol/L SEC61 inhibitor group in-creased significantly (P<0.01),the apoptosis rate and apoptosis index of chondrocytes decreased significantly (P<0.01),SEC61 fluores-cence intensity decreased significantly (P<0.01).Moreover,the expression of GRP78,ATF6,CHOP,MMP-13 protein and mRNA decreased (P<0.05),and the expression of COL2A1 protein and mRNA increased (P<0.05).Compared with the 10％ Guilu Erxian Gel group,the cell activity of chondrocytes in the 2 μmol/L SEC61 inhibitor group increased significantly (P<0.01),the apoptosis rate and apoptosis index of chondrocytes decreased significantly (P<0.01,P<0.05),SEC61 fluorescence intensity decreased significantly (P<0.01),the expression of GRP78,ATF6,CHOP,MMP-13 protein and mRNA decreased (P<0.05),and the expression of COL2A1 protein and mRNA increased (P<0.05).Conclusion:Guilu Erxian Gel can inhibit endoplasmic reticulum stress (ERS) response in degenerative chondrocytes through the ATF6/GRP78/CHOP signaling pathway,regulate the balance of extracellular matrix (ECM) degradation and synthesis,improve the endoplas-mic reticulum homeostasis of chondrocytes,and thereby reduce chondrocyte apoptosis.
Guilu Erxian (龟鹿二仙) GelChondrocyteKnee osteoarthritisActivation of transcription factor 6/glucose regulated protein 78/C/EBP homologous protein signaling pathway
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