Production and secretion of N-terminal secretogranin II derived peptides in GH3B6 prolactin cells.
Chromo/secreto-granins are proteins specific of neuroendocrine cells. Chromogranin B (CgB) and secretogranin II (SgII) are both present in normal and in tumoral (GH3B6) prolactin cells, in which they are colocalized in the same secretory granules. These proteins contain multiple dibasic cleavage sites and are considered as potential precursors of active peptides, though their exact function remains unknown. SgII is sulfated on tyrosine-126. We took advantage of this feature to study its post-translational processing in anterior pituitary cells in primary culture and in GH3B6 cells. Pulse-chase experiments with [35S]sulfate demonstrated the precursor-product relationship between SgII and four N-terminal-derived peptides. Kinetic experiments showed the sequential cleavage of SgII from the C-terminus to the N-terminus. Mature SgII and the derived peptides were secreted by both cell models, and their release was stimulated by TRH (30 nM), a secretagogue of prolactin. These data show that SgII is proteolytically processed into different secreted peptides in prolactin cells and demonstrate that GH3B6 cells provide a good cell model for studying the maturation of SgII in anterior pituitary.
Muller
L
L
Groupe de Biologie de la Cellule Neuroendocrine, Collège de France, CNRS URA 1115, Paris, France.
Tougard
C
C
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002864:Chromogranins; D010450:Endopeptidases / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013431:Sulfates / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D002864:Chromogranins; D007328:Insulin; D010446:Peptide Fragments; D011506:Proteins; D013431:Sulfates; D004958:Estradiol; D013973:Thyrotropin-Releasing Hormone; D004815:Epidermal Growth Factor; D010450:Endopeptidases