LEP
MIM.164160
Image Gallery
Leptin is a peptide hormone secreted by adipose tissue that has been associated with many processes. One of the target tissues of leptin is the hypothalamus where it can act to regulate feeding behavior and metabolism.
Another leptin target is skeletal muscle. Activation of leptin signaling in skeletal muscle activates the AMP-activated protein kinase (AMP-kinase), known to play a key role in signaling in response to nutrients throughout evolution (See AMPK pathway and Snf1 pathway).
AMPK phosphorylates and inactivates the enzyme ACC, acetyl-CoA carboxylase. ACC catalyzes the production of malonyl-CoA from acetyl-CoA.
Malonyl-CoA in turn is an inhibitor of the import of fatty acids into mitochondria by carnitine palmitoyl-transferase I for oxidation and energy production (Mitochondrial carnitine palmitoyl-transferase pathway).
In the presence of leptin, AMPK is activated, ACC is inhibited, and malonyl-CoA levels fall, increasing the oxidation of fatty acids and reducing the lipid content of cells.
The reduced lipid content in skeletal muscle allows insulin signaling and glucose consumption to return to their normal levels, reducing insulin resistance. (From Biocarta)
Pathology
germline mutation in leptin-related obesity (morbid obesity with hypogonadism)