Effects of Galangin on LPS-induced Autophagy and Apoptosis of Rat Articular Chondrocytes by Regulating the SIRT1/AMPK/mTOR Signaling Pathway
Objective To investigate the effect of galangin on lipopolysaccharide(LPS)-induced autophagy and apoptosis of rat articular chondrocytes by regulating the silent information regulator 1(SIRT1)/adenosine 5'-monophosphate-activated protein kinase(AMPK)/mammalian target of rapamycin(mTOR)signaling pathway.Methods Rat articular chondrocytes were grouped into control group,model group(1.0 μg·mL-1 LPS),low concentration galangin group(1.0 μg·mL-1 LPS+10 μmol·L-1 galangin),medium concentration galangin group(1.0 μg·mL-1 LPS+20 μmol·L-1 galangin),high concentration galangin group(1.0 μg·mL-1 LPS+40 μmol·L-1 galangin),high concentration galangin+EX527(SIRT1 inhibitor)group(1.0 μg·mL-1 LPS+40 μmol·L-1 galangin+40 μmol·L-1 EX527).Apoptosis of articular chondrocyte was detected by flow cytometry.Monodansylcadaverine(MDC)staining was applied to observe autophagy of articular chondrocytes.Enzyme linked immunosorbent assay was applied to detect the levels of interleukin(IL)-1β,tumor necrosis factor α(TNF-α),and IL-6 in cells.Western Blot was applied to detect the expression of Beclin,microtubule-associated protein 1 light chain 3(LC3)Ⅱ/Ⅰ,B lymphoblastoma-2-associated X protein(Bax),B lymphoblastoma-2(Bcl-2),SIRT1,AMPK,phosphorylated(p)-AMPK,mTOR,and p-mTOR.Results Compared with the control group,the proportion of MDC positive cells,protein expression of Beclin,LC3 Ⅱ/Ⅰ,Bcl-2 and SIRT1,as well as p-AMPK/AMPK ratio in the model group decreased(P＜0.05),while the apoptosis rate,levels of IL-1β,TNF-α and IL-6,Bax protein expression,and p-mTOR/mTOR ratio increased(P＜0.05).Compared with the model group,the proportion of MDC positive cells,protein expression of Beclin,LC3 Ⅱ/Ⅰ,Bcl-2 and SIRT1,as well as p-AMPK/AMPK ratio in the low-,medium-,and high-concentration galangin groups all increased(P＜0.05),but the apoptosis rate,levels of IL-1β,TNF-α and IL-6,Bax protein expression,and p-mTOR/mTOR ratio decreased(P＜0.05).Compared with the high concentration galangin group,the proportion of MDC positive cells,protein expression of Beclin,LC3 Ⅱ/Ⅰ,Bcl-2 and SIRT1,and p-AMPK/AMPK ratio in the high concentration galangin+EX527 group reduced obviously(P＜0.05),while the apoptosis rate,levels of IL-1β,TNF-α and IL-6,Bax protein expression,and p-mTOR/mTOR ratio increased obviously(P＜0.05).Conclusion Galangin promotes LPS-induced autophagy and inhibits apoptosis in articular chondrocytes,possibly by activating the SIRT1/AMPK/mTOR signaling pathway to exert its effect.
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