Molecular cloning and characterization of the chicken pro-opiomelanocortin (POMC) gene.

The gene for pro-opiomelanocortin (POMC), a common precursor of melanocortins, lipotropins and beta-endorphin, was isolated in the chicken first among avian species. The chicken POMC gene was found to be a single copy gene and appeared to show the same structural organization as that of other species of different classes. The predicted POMC displayed the highest identity to Xenopus POMC(A) (60. 1%), and consisted of 251 amino acid residues with nine proteolytic cleavage sites, suggesting that it could be processed to give rise to all members of the melanocortin family, including adrenocorticotropic hormone and alpha-, beta- and gamma-melanocyte-stimulating hormones, as well as the other POMC-derived peptides. RT-PCR analysis detected the POMC mRNA in the brain, adrenal gland, gonads, kidney, uropygial gland and adipose tissues, each of which has been demonstrated to express melanocortin receptors. These results suggest that melanocortins act in a paracrine and/or autocrine manner to control a variety of functions both in the brain and in the peripheral tissues in the chicken.