Molecular Mechanism Of MiR-378 Regulating Glucose Metabolism Of Skeletal Muscle

Skeletal muscle accounts for about half of the total body mass in healthy body and is quantitiatively the largest insulin sensitive organ in the body,is a major contributor to whole body metabolism.Skeletal muscle is a metabolically flexible organ that can switch between fat and carbohydrate utilization.Muscle contraction and physical activity is associated with enhanced substrate metabolism energy expenditure,and insulin sensitivity.The skeletal muscle,which is the main tissue for glucose uptake after insulin stimulation in the body,plays a very important role in the balance of glucose metabolism.miRNAs are non-coding RNAs that regulate biological processes by interacting with target genes.Studies have found that miRNAs directly or indirectly regulate insulin signaling pathways,and skeletal muscle plays an important role in insulin sensitivity and obesity.At present,the research of miR-378 is mainly focused on follicular development,tumors and lipid metabolism.The study of glucose metabolism is also limited to the liver.However,there is nearly no study on skeletal muscles effect on systemic metabolism through different phenotypes.In this study,miR-378 knockout mice and transfected C2C12 cells were prepared in vitro and vivo experiments for studying the molecular mechanism of miR-378 regulation in skeletal muscle glucose metabolism.Firstly,miR-378 knockout mice and wild type mice(WT)were subjected to glucose metabolism experiments.Secondly,mice were induced to detect glucose metabolism with high fat diet.Finally,metabolome,transcriptome,and proteome were performed in mice quadriceps and C2C12 cells.The results showed that:(1)Compared with WT,glucose tolerance tolerance,insulin sensitivity and pyruvate tolerance were significantly increased in KO.The phosphorylation level of key node protein AKT in the insulin pathway of KO Qua was significantly increased.The expression of promoting gluconeogenic pathway genes PCK were significantly lower in KO than WT in skeletal muscle,and suppressing gluconegenic pathway genes SHP were significantly higher in KO than WT in skeletal muscle.The glycolytic pathway genes,such as HK1,GPI1 and PFKM,were significantly higher in KO than WT.(2)After high-induced,the weigh gain of KO was slower than WT,and liver H&E staining showed that the lipid droplets in KO were significantly smaller than those in WT.Glucose tolerance,insulin sensitivity and pyruvate tolerance results were consistent with normal feeding mice.The key node protein AKT phosphorylation in the insulin signaling pathway was significantly increased in KO than WT.(3)After inhibitor of miR-378 in cells,the lactate content was significantly increased,and the phosphorylation of AKT and IR,which the key node proteins of the insulin signaling pathway,were significantly increased.(4)The GO and KEGG analysis of transcriptome and proteome indicated that miR-378 was involved in glucose metabolism.Conclusion: the study demonstrated that miR-378 can regulate glucose homeostasis in vitro and in vivo,which clarifying its molecular mechanism of regulating glucose metabolism,providing an important theoretical basis for the treatment of obesity and diabetes.