Regulation of IGF binding proteins by FSH in human luteinizing granulosa cells.
OBJECTIVE
To evaluate the regulation of the secretion of insulin-like growth factor (IGF) binding proteins (IGFBPs) by FSH in human luteinizing granulosa cells.


RESULTS
Luteinizing granulosa cells were incubated with and without FSH. Levels of IGFBP-1 and -3 in the medium were measured by EIA and RIA, respectively and binding activities of these IGFBP were evaluated by Western ligand blot. FSH inhibited the secretion of IGFBP-1 dose dependently. FSH did not inhibit the secretion of immunoreactive IGFBP-3, but inhibited the binding activity of IGFBP-3. To assess the protease activity, 125I-IGFBP-3 was incubated with the cultured medium. 125I-IGFBP-3 degraded into small fragments when it was incubated with the cultured medium treated with FSH.


CONCLUSIONS
FSH enhances the action of IGF-I in human granulosa cells by inhibiting the secretion of IGFBP-1 and the binding activity of IGFBP-3 by stimulating the proteolysis of IGFBP-3.
Adachi
T
T
Department of Obstetrics and Gynecology, Tokyo Women's Medical College, Japan.
Iwashita
M
M
Kuroshima
A
A
Takeda
Y
Y
D015153:Blotting, Western; D002478:Cells, Cultured; D003470:Culture Media / Q000032:analysis / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000378:metabolism / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000032:analysis / Q000494:pharmacology*; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000378:metabolism*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D011863:Radioimmunoassay
D003470:Culture Media; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D010450:Endopeptidases