Identification of carp proopiomelanocortin-related peptides and their effects on phagocytes

We report the immunomodulating effects of proopiomelanocortin (POMC)-relate d peptides on phagocytic cells in carp. The complete amino acid sequences o f two carp POMCs (I and II) were deduced from the nucleotide sequences afte r cDNA cloning. Both POMCs consist of 194 amino acids (91% sequence identit y) including identical alpha-melanotropin (MSH) and beta-endorphin (EP). Al l hormonal peptides derived from two POMCs were identified by mass spectrom etry after separation by high-performance liquid chromatography of an acid- acetone extract from a single pituitary. These peptides were alpha-MSH, N-D es-Ac-alpha-MSH, di-Ac-alpha-MSH, beta-MSH I, beta-MSH-II, N-Ac-beta-EP(1-2 9), corticotropin-like intermediate lobe peptide I and II and N-terminal pe ptide of POMC I and II. The immunomodulating effects of synthetic MSHs and EPs on phagocytic cells from carp head kidney were examined. Di-Ac-alpha-MS H, beta-MSH I, N-Ac-beta-EP(1-29) and beta-EP(1-29) increased the productio n of superoxide anion at 0.1-100 ng ml(-1) for these MSHs and 1-100 ng ml(- 1) for EPs in RPMI 1640 medium. (C) 2000 Academic Press.