Ontogeny of a novel decapeptide derived from POMC-A in the brain and pituitary of the rainbow trout.
Trout POMC-A exhibits a unique C-terminal extension of 25-amino acids which is processed in the pituitary and hypothalamus to generate two novel decapeptides, EQWGREEGEE and ALGERKYHFQ-NH(2). The fibers containing these two decapeptides are widely distributed in the brain, suggesting that they may exert neurotransmitter or neuromodulator activities. In the present study, we have investigated the ontogeny of the decapeptide EQWGREEGEE in the trout pituitary and brain. In the pituitary of 29-day embryos and 33-day alevins, EQWGREEGEE-immunoreactive material was observed in a cluster of cells located in the central and rostral region of the gland, respectively. In 47-day alevins, a second group of cells exhibiting EQWGREEGEE-like immunoreactivity was detected in the caudal region of the pituitary and the intensity of labeling in these cells increased in 61-day fry. In the brain, EQWGREEGEE immunoreactivity was detected in 47-day alevins. In 47- and 61-day larvae, immunoreactive elements were mainly detected in the diencephalon. Characterization of the immunoreactive material by reversed-phase high-performance liquid chromatographic analysis combined with radioimmunoassay detection revealed the existence of two major forms which exhibited different retention times than synthetic EQWGREEGEE. The present study indicates that EQWGREEGEE-related peptides are present in the trout pituitary early during ontogeny and appear in the brain only later, and that processing of the C-terminal extension of POMC-A generates distinct molecular species at different developmental stages. These data suggest that alternative processing of the C-terminal domain of POMC-A gives rise to various peptide products that may exert specific activities during trout development.
Tollemer
Hélène
H
European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U 413, UA CNRS, University of Rouen, 76821 Mont-Saint-Aignan, France.
Vallarino
Mauro
M
Tonon
Marie-Christine
MC
Vaudry
Hubert
H
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism*; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods; D004625:Embryo, Nonmammalian; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods; D017686:Oncorhynchus mykiss; D010455:Peptides / Q000032:analysis / Q000737:chemistry; D010902:Pituitary Gland / Q000196:embryology / Q000378:metabolism*; D011247:Pregnancy; D011333:Pro-Opiomelanocortin / Q000737:chemistry / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods
D010455:Peptides; D011333:Pro-Opiomelanocortin