Insulin-like growth factor-binding protein (IGFBP)-1, -2, -3, -4, -5, and -6 and IGFBP-related protein 1 during rainbow trout postvitellogenesis and oocyte maturation: molecular characterization, expression profiles, and hormonal regulation.
In the present study we report the full coding sequence of rainbow trout IGF-binding protein-1 (IGFBP1), -2, -3, -5, and -6 and IGFBP-related protein-1 (IGFBP-rP1) mRNAs as well as the partial coding sequence of IGFBP-4 mRNA. To our knowledge, this is the first report of IGFBP4, IGFBP6, and IGFBP-rP1 in a nonmammalian species. The tissue distribution of all mRNAs was studied, and the ovarian expression profiles of IGFBP2 to -6 and IGFBP-rP1 between late vitellogenesis and oocyte maturation were characterized. In addition, in vitro hormonal regulation by the maturation-inducing steroid 17,20beta-dihydroxy-4-pregnen-3-one (17,20betaP), gonadotropin, and estradiol were studied. We observed that besides IGFBP1, which was only found in liver, IGFBP2 to -6 and IGFPB-rP1 were expressed in the preovulatory ovary. IGFBP3 was also detected in liver, trunk, kidney, skin, and gills, whereas IGFBP2 to -6 and IGFBP-rP1 exhibited a wider tissue distribution. In the preovulatory ovary, IGFBP3 was strongly down-regulated during the postvitellogenesis period, whereas IGFBP5 exhibited a limited up-regulation. In addition, IGFBP6 and IGFBP-rP1 were up-regulated during oocyte maturation. Hormonal regulation data indicated that all ovarian IGFBPs and IGFBP-rP1 transcripts are regulated under gonadotropic stimulation at a concentration that induced 100% oocyte maturation. In addition, IGFBP2 to -5 transcripts are regulated by 17,20betaP and estradiol. Together, our observations strongly suggest that during final oocyte maturation, a down-regulation of IGFBP3, -4, and -5 occurs in the oocyte in response to gonadotropic and 17,20betaP (IGFBP3 and -5) stimulation, whereas an up-regulation of IGFBP2 and -6 occurs in follicular layers or extrafollicular tissue in response to gonadotropic stimulation.
Kamangar
Barzan Bahrami
BB
Institute National de la Recherche Agronimique, SCRIBE, Institut Fédératif de Recherche 140, Rennes, France.
Gabillard
Jean-Charles
JC
Bobe
Julien
J
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D020224:Expressed Sequence Tags; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006728:Hormones / Q000378:metabolism; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000096:biosynthesis*; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000096:biosynthesis*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000096:biosynthesis*; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000096:biosynthesis*; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000096:biosynthesis*; D018976:Insulin-Like Growth Factor Binding Protein 6 / Q000096:biosynthesis*; D018969:Insulin-Like Growth Factor Binding Proteins / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss; D009865:Oocytes / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism; D010802:Phylogeny; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014818:Vitellogenesis
D018076:DNA, Complementary; D006728:Hormones; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D018974:Insulin-Like Growth Factor Binding Protein 4; D018975:Insulin-Like Growth Factor Binding Protein 5; D018976:Insulin-Like Growth Factor Binding Protein 6; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; C102529:insulin-like growth factor binding protein-related protein 1; D004958:Estradiol; D012313:RNA