YM268 increases the glucose uptake, cell differentiation, and mRNA expression of glucose transporter in 3T3-L1 adipocytes

The purpose of this study was to examine the effects of bis[4-[2,4-dioxo-5-thiazolidinyl)methyl] (YM268), a thiazolidinedione derivative, on glucose uptake, adipocyte differentiation through peroxisome proliferator-activated receptor gamma (PPAR gamma), and phosphatidylinositol 3-kinase (PI 3-kinase) activity in cultured cells. YM268 and pioglitazone dose-dependently increased the 2-deoxyglucose uptake in 3T3-L1 cells. YM268 facilitated the insulin-stimulated triglyceride accumulation in 3T3-L1 adipocytes and increased the mRNA expression of fatty acid-binding protein. YM268, with and without insulin, increased the mRNA expression of glucose transporter isoforms such as GLUT1 and GLUT4, indicating enhancement of adipocyte differentiation. Additionally, YM268 and pioglitazone showed activity of the PPAR gamma ligand, a member of the nuclear receptor superfamily responsible for adipogenesis. To examine the possible involvement of the increased activity of PI 3-kinase in YM268-stimulated glucose uptake, the enzyme activity was estimated by measuring the phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P-3) concentration in human monocytic cells. Insulin dose-dependently increased the PI-3,4,5-P-3 production but YM268 had no significant effect on the insulin-dependent and -independent PI 3-kinase activation. These results indicate that the mechanism by which YM268 increased glucose uptake. may be accounted for in part by the enhancement of GLUT1 and GLUT4 expression through PPAR gamma activation.