RESUMO
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 immuno- histochemistry 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 .
RESUMO
Objective To screen the secretory factor-related, mechanoresponsive microRNAs (miRNA) of osteocytes. Methods Cyclic mechanical tensile strain (ε=2.5,f=0.5 Hz) was applied to osteocytes and osteoblasts cultured in vitro respectively, and the differentially expressed miRNAs only in the osteocytes were screened out by using miRNA chip. Through bioinformatics technology, in these differentially expressed miRNAs, the target genes of secretory factors including insulin-like growth factor-1(IGF-1), nitric oxide synthesase (NOS), fibroblast growth factor 23 (FGF23) and sclerostin (SOST) were further screened out. Then the selected miRNAs were compared with the biochip detected, differentially expressed miRNAs in femur bone of the mice which were trained on treadmill, and four of these miRNAs were randomly selected for quantitative PCR verification. Results For the 77 differentially expressed miRNAs only in the mechanically strained osteocytes in vitro, 22 miRNAs whose target genes were the 4 secreted factors (IGF-1, NOS, FGF23 and SOST), were screened out. Moreover, a total of 11 miRNAs in the 22 miRNAs were differentially expressed in femur bone of the treadmill trained mice with the same trend as those in osteocytes in vitro, and the randomly selected miR-361-3p, miR-3082-5p, miR-6348 and miR-706 were confirmed to be differentially expressed with the same trend in femur bone and osteocytes. Conclusions These mechanoresponsive miRNAs differentially expressed only in osteocytes, such as miR-361-3p, miR-3082-5p, miR-6348 and miR-706, probably influence osteoblastic differentiation or bone metabolism through regulating the secretory factors.