Role of peroxisome proliferator-activated receptor-gamma in the glucose-sensing apparatus of liver and beta-cells.

Type 2 diabetes develops in the context of both insulin resistance and beta-cell failure. Thiazolidinediones are a class of antidiabetic agents that are known to improve insulin sensitivity in various animal models of diabetes. The improved insulin sensitivity may be achieved either by systemic insulin sensitization or by direct action of peroxisome proliferator-activated receptor (PPAR)-gamma on the transcription of genes involved in glucose disposal. Evidence supporting the direct action of PPAR-gamma on glucose metabolism is observed in the genes involved in insulin-stimulated glucose disposal. We already showed that GLUT2 and beta-glucokinase were directly activated by PPAR-gamma. Recently, we have identified and characterized the functional PPAR response element in the GLUT2 and liver type glucokinase (LGK) promoter of the liver. It is well known that adipose tissue plays a crucial role in antidiabetic action of PPAR-gamma. In addition, PPAR-gamma can directly affect liver and pancreatic beta-cells to improve glucose homeostasis.