Molecular evolution of the neuropeptide Y (NPY) family of peptides: cloning of three NPY-related peptides from the sea bass (Dicentrarchus labrax)

Neuropeptide Y (NPY) is a 36-amino-acid peptide that is widely and abundant ly expressed in the central nervous system of all vertebrates investigated. Related peptides have been found in various vertebrate groups: peptide YY (PYY) is present in gut endocrine cells of many species and pancreatic poly peptide (PP) is made in thr pancreas of all tetrapods. In addition, a fish pancreatic peptide called PY has been reported in three species of fishes. The evolutionary relationships of fish PY have been unclear and it has been proposed to be the orthologue (species homologue) of each of the three tet rapod peptides. We demonstrate here with molecular cloning techniques that the sea bass (Dicentrarchus labrax), an acanthomorph fish, has orthologues of both NPY and PYY as well as a separate PY peptide. Sequence comparisons suggest that PY arose as a copy of the PYY gene, presumably in a duplicatio n event separate from the one that generated PP from PYY in tetrapods. PY s equences from four species of fish indicate that, similar to PP, PY evolves much more rapidly than NFY and PYY. The physiological role of PY is unknow n, but we demonstrate here that sea bass PY, like NPY and PYY but in contra st to the tetrapod PP, is expressed in brain. (C) 2000 Elsevier Science B.V . All rights reserved.