title: Follicle-stimulating hormone-stimulated secretion of an immunoreactive 29 kDa inhibin alpha-subunit complex, but not of 32 kDa bioactive inhibin, from cultured immature rat Sertoli cells.
abstract: The medium of cultured Sertoli cells from immature rat testes contains 29 and 32 kDa proteins, which are recognized by an antiserum against the 22 N-terminal amino acids of the inhibin alpha-subunit. These proteins were detected by immunoprecipitation of labelled proteins after incubation of Sertoli cells with [35S]methionine, and by Western blotting. The amount of the 32 kDa protein was not affected by the addition of follicle-stimulating hormone (FSH) to the culture medium of the Sertoli cells, whereas FSH induced a large increase of the amount of the 29 kDa protein. Finally, the 29 and 32 kDa proteins in the medium from control and FSH-stimulated Sertoli cells were separated by sodium dodecyl sulfate-polyacrylamide electrophoresis, and inhibin bio- and immunoactivity were determined in eluates of the slices of the gel. Equal amounts of bioactivity were found in control and FSH-stimulated samples at 32 kDa, while the amount of immunoactivity at 29 kDa was increased; no bioactivity was detected in the eluates of these slices. It is concluded that FSH stimulates the secretion of a 29 kDa inhibin-like protein, which does not contain inhibin bioactivity. This indicates that results of experiments, in which antibodies against N-terminal peptides of the inhibin alpha-subunit are used to detect inhibin, do not necessarily reflect the amount of bioactive inhibin produced.
authors: Department of Biochemistry (Division of Chemical Endocrinology), Erasmus University Rotterdam, The Netherlands.
authors: A J
authors: AJ
authors: Grootenhuis
authors: W M
authors: WM
authors: van Beurden
authors: M A
authors: MA
authors: Timmerman
authors: F H
authors: FH
authors: de Jong
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D007265:Inhibins / Q000378:metabolism*; D008297:Male; D011233:Precipitin Tests; D051381:Rats; D011919:Rats, Inbred Strains; D012708:Sertoli Cells / Q000378:metabolism*
chemical_list: D003470:Culture Media; D007265:Inhibins; D005640:Follicle Stimulating Hormone