[Leptin--a peptide hormone from adipocytes. Sensation of the 23rd FEBS Meeting]

Abstract

Studies of the obese gene are reviewed. Recessive mutations in the ob gene in homozygous state cause excessive weight and diabetes in mice. Cloning and expression of cDNA of the human and mouse ob genes revealed that the ob gene is only expressed in white adipose tissue. cDNA encodes the ob protein that consists of 167 amino acid residues, the homology between the mouse and human ob proteins being 84%. The peptide leptin, secreted into blood, consists of 145 amino acid residues and results from the cleavage of a signal peptide off the ob protein. Leptin was obtained by genetic engineering methods. Its injection into ob/ob mice decreases body weight and eliminates diabetes symptoms. Leptin also decreased body weight of healthy mice by activating the utilization of endogenous lipids in energy metabolism. Leptin was found in human and mouse blood and mouse adipose tissue but not in blood or adipose tissue of ob/ob mice. Based on the results obtained, it was postulated that leptin, a product of the ob gene, is a hormone that is secreted into blood in varying quantities by adipocytes and controls the adipose tissue weight by stimulating lipid metabolism in the organism.