| To examine glucose uptake activity of Fibroblast Growth Factor-21(FGF-21) on HL-7702human live cells and Rat L6muscle cells. To establish an insulin resistance cell model and evaluate the effects and mechanisms of FGF-21on insulin resistance.Culture HL-7702liver cells, and use high concentrations of insulin and dexamethasone to induced insulin resistant model. Culture L6myoblasts and differentiate them into mature muscle cells, and use dexamethasone to induce L6cells to establish insulin resistant model. The experiment has five group, the control group (C), the IR control group (IR control), insulin treatment group, and FGF-21treatment group. Use glucose oxidase (GOD-POD) method kit to determine the glucose uptake.Use western blotting to detect the protein expression levels of GLUT1, GLUT4, IRS1; and to detect the phosphorylation levels phosphorylated of IRS1and ERK1/2.When the concentration of FGF-21is between3.1mg·L-1and100mg·L-1, it may significantly induce HL-7702cells glucose uptake compared to the control group (P<0.05), and they follow the dose-dependent manner. Besides, it may have cumulative effect when combined with insulin. In L6muscle cells, when the concentration of FGF21is between3.91mg·L-1and250mg·L-1, it may significantly promote the glucose uptake, compared with the control group (P<0.05), and they follow the dose-dependent manner. Besides, it may have cumulative effect when combined with insulin. We made a IR model of HL-7702cells which was induced by insulin (34.4μmol·L-1) and dexamethasone (2μmol·L-1) three days, and we made a IR model on L6cells which was induced by dexamethasone (1μmol·L-1) four days. In the subsequent IR model experiments, FGF-21may improve glucose uptake of liver and muscle cells in the IR state. In The HL-7702cells IR model, after administrated FGF-21for24h, the expression of GLUT1was significantly increased, however, GLUT4is not expressed, and the expression and phosphorylation level of IRS1did not change. In L6IR cells, when FGF-21was administrated for5min, the phosphorylation of ERK1/2increases. When PD98059, the ERK1/2specific inhibitor, was administrated, FGF-21’s ability to promote the phosphorylation of ERK1/2was inhibited. In L6cells IR model, when FGF-21is administrated for24h, the expression of GLUTl does not decrease significantly, the expression of GLUT4does not change, and the expression of IRS1decreases significantly. In IR muscle cells, when FGF-21is used for10min, the phosphorylation content of ERK1/2increase. And when PD98059was administrated, the ability of FGF-21to promote ERK1/2phosphorylation and muscle cell glucose uptake was inhibited.FGF-21can enhance the glucose uptake of HL-7702liver cells and L6muscle cells, and improved glucose uptake under the insulin resistance; but the mechanisms of Two types of cells is different on glucose uptake. In IR model cells, FGF-21does not change the expression of GLUT4, but can increase the expression of p-ERK1/2in both cells, and can be inhibited by ERK1/2specific inhibitor. In muscle cells, the ability of FGF-21to promote glucose uptake was also partially inhibited by the inhibitor. The results indicated that FGF-21can improve IR glucose metabolism through the ERK1/2pathway. FGF-21can improve the expression of GLUT1in HL-7702cells, but do not improve expression of GLUT1in L6cells, it suggested that FGF-21improve IR glycometabolism through enhancing the expression of GLUT1in the liver cells, but FGF-21improve IR glycometabolism through other transportprotein in the muscle cells. In the IR model, FGF-21could not impact the expression and phosphorylation of IRSI in liver cells, the effect of FGF-21could be decreased in muscle cells., and suggested that the enhancing glucose uptake of FGF-21do not depend on insulin pathway in the liver cells and the muscle cells, the IR cells glycometabolism of Blood sugar mediate such as liver, muscle, lipid, were improved by FGF-21, we show that FGF-21could improve the body’ insulin resistance of body from the cellular level. |
