Figure 1.

Regulation of liver metabolism by insulin. Insulin stimulates the expression of genes encoding glycolytic and lipogenic enzymes (green), but inhibits the expression of those encoding gluconeogenic enzymes (red). The induction of gene expression by insulin is mediated by the transcription factor sterol regulatory element binding protein (SREBP), the repression of expression is mediated by forkhead box O1 (FOXO1). Insulin also regulates the activity of glycogen synthase and citrate lyase (blue). Insulin activates glycogen synthase promoting its dephosphorylation through inhibition of protein kinase A (PKA) and glycogen-synthase-kinase-3 (GSK-3). IR, insulin receptor; GLUT2, glucose transporter 2; PEPCK, phosphoenolpyruvate carboxykinase; ACC, acetyl-CoA carboxylase; FAS, fatty acid synthase (Adapted from [51]).