灰树花多糖改善地塞米松诱导的小鼠骨骼肌细胞系C2C12模型肌管的萎缩OA

Objective To investigate the mechanism by which Grifola frondosa polysaccharide(GFP)mitigates dexamethasone(DEX)-induced atrophy of myotubes in mouse skeletal muscle cell line C2C12(C2C12 myotube).Methods C2C12 cells were divided into normal group(NOR),dexamethasone group(DEX),low-dose GFP(GFP-L),medium-dose GFP(GFP-M)and high-dose GFP-H intervention DEX groups(concentrations of 20,50,and 100 μg/mL,respectively).Immunofluorescence microscopy and Western blot were employed to assess my-osin heavy chain(MyHC)expression.Western blot and RT-qPCR were utilized to evaluate the protein and mRNA levels of muscle-specific ring finger protein 1(MuRF1),muscle atrophy F-box protein(Atrogin1)as well as phosphorylation of AMPK and forkhead box protein O3(FOXO3a).The expression of SIRT1.ATP and mitochon-drial protein content were measured with commercially available kits.Results GFP-M and GFP-H groups signifi-cantly increased myotube length,fusion index and MyHC expression in DEX-treated cells(P＜0.05).Additionally,GFP treatment markedly down-regulated the protein and mRNA expression level of Atrogin1,MuRF1 and Myostatin(P＜0.05).The phosphorylation level of AMPK and FOXO3a and the expression of SIRT1 were also significantly reduced(P＜0.05).The SIRT1 inhibitor-induced aberrant expression of FOXO3a,Atrogin1,and MuRF1 was effec-tively reversed by GFP.Conclusions Grifola frondosa polysaccharide may alleviate DEX-induced atrophy of C2C12 myotubes through a SIRT1-mediated AMPK/FOXO3a signaling pathway.