The Molecular Mechanisms Underlying MiR-26b Affecting Insulin Sensitivity In Adipocyte

Objective: To elucidate the molecular mechanisms underlying mi R-26 b affecting insulin sensitivity in adipocyte.Methods:1. The male SD rats were fed with high fat diet to induce obesity. 3T3-L1 and HPA-V adipocytes were cultured in medium containing high glucose and high insulin to induce insulin-resistant.2. mi R-26 b expression level was determined using real time PCR.3. 3T3-L1 pre-adipocytes were induce to differentiate into matured adipocytes using 3-isobutyl-1-methylxanthine, dexamethasone and insulin. HPA-V pre-adipocytes were induce to differentiated into matured adipocytes using3-isobutyl-1-methylxanthine, dexamethasone, insulin and rosiglitazone.4. HPA-V pre-adipocytes were infected with recombinant lentiviral vector expressing mi R-26 b to achieve mi R-26 b overexpression, and infection efficiency was obeserved under fluorescence microscopy after 48 h.5. The insulin sensitivity in adipocytes were evaluated by assaying uptake rates of 2-deoxy-D-[3H]-glucose.6. The insulin recepor(IR), insulin receptor substrate(IRS), AKT, glucose tranporter 4(GLUT4) protein levels were assessed using western blot analysis.7. The target gene of mi R-26 b was predicted by bioinformatic methods, which was validated using luciferase reporter assay system.Results:1. The SD rats fed with high-fat diet exhibited the characteristic features of obesity and metabolic disorders, which demonstrated the establishment of DIO rats.The mi R-26 b expression levels were significantly decreased in mesenteric adipose tissue from DIO rats, which was correlated negatively with HOMA-IR.2. Mi R-26 b expression levels were significantly reduced in insulin-resistant3T3-L1 and HPA-V adipocytes compared with control adipocytes.3. Overexpression of mi R-26 b significantly improved insulin-stimulated glucose uptake in mature adipocytes.4. Overexpression of mi R-26 b significantly promoted insulin-stimulated GLUT4 translocation to the plasma membrane in adipocytes.5. Overexpression of mi R-26 b significantly increased insulin-stimulated serine phosphorylation of AKT(p-AKT) in adipocytes.6. PTEN is the direct target of mi R-26 b.Conclusion: mi R-26 b promote insulin sensitivity in adipocytes through regulating PTEN-PI3K/Akt signaling pathway.