白藜芦醇促进肥胖小鼠骨骼肌中FNDC5降解的机制

The mechanism of resveratrol promoting FNDC5 degradation in skeletal muscle of male obese mice

目的研究白藜芦醇通过诱导自噬促进肥胖小鼠骨骼肌组织中纤连蛋白Ⅲ型结构域包含5(FNDC5)降解的机制。方法将6周龄雄性C57BL/6小鼠随机分为标准饮食(SCD)组、高脂(HFD)组及高脂+白藜芦醇(HFD+RES)组,HFD+RES组在HFD的同时胃饲白藜芦醇(400 mg/kg·d),共持续20周。测定体质量、血清甘油三酯、总胆固醇、低密度脂蛋白、高密度脂蛋白,HE染色检测骨骼肌的病理学变化。免疫组化、RT-PCR和Western blot分析和纤连蛋白Ⅲ型结构域包含5(FNDC5)、沉默信息调节因子(SIRT)-1、SIRT2、微管相关蛋白1轻链3α(LC3)、选择性自噬接头蛋白(p62)、Bcl-2同源结构域蛋白抗体(Beclin-1)、噬相关5同源物(ATG5)、噬相关7同源物(ATG7)的表达。结果HFD组小鼠体质量增高,血清TG、TC和LDL-C水平显著升高,HDL-C水平下降;骨骼肌纤维间出现脂肪沉积;SIRT1、SIRT2和LC3的蛋白表达水平降低,而FNDC5和p62的蛋白表达升高。FNDC5的表达水平升高,SIRT1、SIRT2、LC3、Atg7和Beclin-1的基因表达水平降低。RES组可逆转HFD的效应,增加SIRT1、SIRT2和自噬相关基因的表达。结论白藜芦醇可减少骨骼肌FNDC5表达的效应,其机制可能与其增加SIRT1和SIRT2的表达,进而促进自噬和FNDC5的降解有关。

Objective To investigate the mechanism of resveratrol promoting fibronectin type Ⅲ domain-containing 5(FNDC5)degradation in skeletal muscle of male obese mice.Methods Six-week-old male C57BL/6 mice were randomly divided into three groups:standard control diet(SCD),high-fat diet(HFD)and high-fat diet treated with resveratrol(HFD+RES).HFD+RES group was intervened with resveratrol via gavage[400 mg/kg·d]while fed HFD for 20 weeks.The body mass,serum TG,TC,LDL-C and HDL-C levels were detected.The pathological changes in skeletal muscle were detected by HE staining.The expression of FNDC5,SIRT1,SIRT2,LC3,p62,Beclin-1,ATG5,ATG7 was assessed by immunohistochemistry,RT-PCR and Western blot respectively.Results The body mass,serum TG,TC and LDL-C levels increased significantly,meanwhile HDL-C levels decreased in HFD group.Lipid deposition between skeletal muscle fibers were obvious in HFD group.The immunohistochemistry results showed that protein expression levels of SIRT1,SIRT2 and LC3 obviously decreased,while the protein levels of FNDC5 and p62 obviously increased.The expression levels of FNDC5 significantly increased,while the gene expression levels of SIRT1,SIRT2,LC3,Atg7 and Beclin-1 obviously decreased.All these responses were attenuated by treatment with RES.Conclusion RES has obvious effects of lipid-lowering and promoting FNDC5 degradation in skeletal muscle tissues,which may be related with SIRT1 and SIRT2-induced autophagy,thus resulting in degradation of FNDC5.