Regulation and physiological role of insulin-like-growth-factor-binding protein-1 in human granulosa cells.
The present study was undertaken to elucidate the physiological role and the regulation of insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) in human luteinizing granulosa cells. IGFBP-1 abolished IGF-I-stimulated estradiol production by luteinizing granulosa cells in a dose-dependent manner with a 50% inhibitory concentration (IC50) of 0.27 nM. Similarly, IGFBP-1 inhibited 125I-IGF-I binding to granulosa cells. IGFBP-1 was identified by Western immunoblot and specific enzyme immunoassay in the granulosa-cell-conditioned medium after 24 h culture. Immunoreactive IGFBP-1 released into the medium was inhibited by both IGF-I and follicle-stimulating hormone dose-dependently with an IC50 of 0.14 and 0.13 nM, respectively, while human chorionic gonadotropin-stimulated IGFBP-1 release with a 50% effective dose (ED50) of 0.6 nM. These results suggest that IGFBP-1 is involved in follicular development and granulosa cell differentiation in the human ovary and that gonadotropins may influence IGF-I action by modifying IGFBP-1 levels within the ovary.
Iwashita
M
M
Maternal and Perinatal Center, Tokyo Women's Medical College, Japan.
Adachi
T
T
Katayama
E
E
Kudo
Y
Y
Takeda
Y
Y
D001667:Binding, Competitive; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D002454:Cell Differentiation; D004958:Estradiol / Q000096:biosynthesis / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D015151:Immunoblotting; D007328:Insulin / Q000378:metabolism; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D006080:Ovarian Follicle / Q000502:physiology
D002352:Carrier Proteins; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D005640:Follicle Stimulating Hormone