PDK-1/FoxO1 pathway in POMC neurons regulates Pomc expression and food intake.

Both insulin and leptin signaling converge on phosphatidylinositol 3-OH kinase [PI(3)K]/3-phosphoinositide-dependent protein kinase-1 (PDK-1)/protein kinase B (PKB, also known as Akt) in proopiomelanocortin (POMC) neurons. Forkhead box-containing protein-O1 (FoxO1) is inactivated in a PI(3)K-dependent manner. However, the interrelationship between PI(3)K/PDK-1/Akt and FoxO1, and the chronic effects of the overexpression of FoxO1 in POMC neurons on energy homeostasis has not been elucidated.

Forkhead transcription factor FoxO1 in adipose tissue regulates energy storage and expenditure.

Objective: Adipose tissue serves as an integrator of various physiological pathways, energy balance, and glucose homeostasis. Forkhead box-containing protein O subfamily (FoxO) 1 mediates insulin action at the transcriptional level. However, physiological roles of FoxO1 in adipose tissue remain unclear.

The FoxO transcription factors and metabolic regulation.

Forkhead transcription factors FoxOs are conserved beyond species and regulated by insulin signaling pathway. FoxOs have diverse functions on differentiation, proliferation and cell survival. In calorie restriction (CR) or starvation, FoxOs are in nucleus, active transcriptionally, and increase hepatic glucose production, decrease insulin secretion, increase food intake and cause degradation of skeletal muscle for supplying substrates for glucose production.