ABSTRACT
Objective:To investigate the role of stress-inducible protein Sestrin2 (Sesn2) in the improvement of insulin resistance in rat L6 skeletal muscle cells treated with liraglutide.Methods:The establishment of insulin resistance model of rat L6 skeletal muscle cells was induced by palmitate. The experimental cells were divided into control group(Con group), palmitate 0.6 mmol/L treatment group(PA group), palmitate 0.6 mmol/L+ liraglutide 10 nmol/L treatment group(PA+ Lir10 group), palmitate 0.6 mmol/L+ liraglutide 100 nmol/L treatment group(PA+ Lir100 group), and palmitate 0.6 mmol/L+ liraglutide 1 000 nmol/L treatment group(PA+ Lir1000 group). The cell counting kit 8(CCK8) method was used to detect the cell activity in each group. Western blotting was used to detect the expression levels of glucose transporter 4(GLUT4), protein kinase B(Akt), phosphorylated protein kinase B(p-Akt), and Sesn2 protein in L6 cells. L6 cells were transfected with siRNA to inhibit the expression of Sesn2. The cells were treated with palmitate and liraglutide. Western blotting was used to detect the expression levels of Sesn2, Akt, p-Akt, and GLUT4 protein in L6 cells.Results:Compared with Con group, the cell survival rate, p-Akt/Akt ratio, Sesn2, and GLUT4 protein expression in PA group decreased significantly( P<0.05). After liraglutide intervention, the cell activity, p-Akt/Akt ratio, Sesn2, and GLUT4 protein expression of PA+ Lir100 and PA+ Lir1000 groups was increased( P<0.05). After inhibiting the expression of Sesn2, p-Akt/Akt ratio and GLUT4 protein in transfected si-Sesn2 and treated with 0.6 mmol/L palmitate group(PA+ si-Sesn2 group) and transfected si-Sesn2 and treated with 0.6 mmol/L palmitate+ liraglutide 100 nmol/L group (Lir100+ PA+ si-Sesn2 group) were significantly lower than those in transfection negative group (si-Con group; P<0.05). Even after liraglutide intervention, compared with PA+ si-Sesn2 group, p-Akt/Akt ratio and GLUT4 protein expression level were not significantly increased in Lir100+ PA+ si-Sesn2 group ( P>0.05). Conclusions:Palmitate could induce the decrease of p-Akt/Akt ratio and GLUT4 protein expression in L6 cells. Liraglutide upregulates the expression of Sesn2, which leads to the increase of p-Akt/Akt ratio and GLUT4 protein expression and contributes to the improvement of insulin resistance.
ABSTRACT
Objective Cloning and expression of Par6A.Methods Par6A cDNA was amplified from rat L6 skeletal muscle cells by RT-PCR and the cloning and expression vectors of Par6A were constructed.The expression vector was transfected into 293 cells.Furthermore,the function of Par6A was confirmed by Co-immunoprecipitation.Results Par6A cDNA with approximately 1 kb in length was successfully amplified,and the expression vector of pDsRed-Express-N1-Par6A was constructed.The red fluorescene was seen under fluorescent microscope after 293ET cells were transfected for 24 h using the pDsRed-Express-N1-Par6A vector.The expressed Par6A protein can interacte with PKC?.Conclusion We successfully cloned the Par6A cDNA from rat L6 skeletal muscle cells,which provided a reliable method to study the function of Par6A.