Opposite vectorial secretion of insulin-like growth factor I and its binding proteins by pig Sertoli cells cultured in the bicameral chamber system.
A two-chamber system has been employed to investigate the vectorial secretion of insulin-like growth factor I (IGF-I) and its binding proteins (IGF-BPs) by pig Sertoli cells. The kinetics of transport of [3H]insulin as well as the transepithelial electrical resistance of filters coated with reconstituted basement membrane, in the absence of presence of Sertoli cells, indicated the formation of a functional barrier by Sertoli cells. The rates of diffusion of [125I]IGF-I or [125I]human CG were slower from the apical (AC) to the basal (BC) compartment than in the opposite direction. However, the IGF-I content and concentration in the BC was twice that seen in the AC. FSH increased the secretion of IGF-I in the BC, and therefore increased the BC/AC ratio. In contrast, most of the IGF-BPs, with apparent molecular sizes of 39-43, 34, 29 and 24 kDa, were secreted in the AC. FSH increased the secretion of IGF-BP 39-43 kDa (BP3). This is the first report of opposite vectorial secretion of IGF-I and its binding protein by any cell type.
Skalli
M
M
INSERM U 307, Hôpital Debrousse, Lyon, France.
Avallet
O
O
Vigier
M
M
Saez
J M
JM
D000818:Animals; D001485:Basement Membrane / Q000502:physiology; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism; D004058:Diffusion; D004553:Electric Conductivity; D004848:Epithelium / Q000502:physiology; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D012708:Sertoli Cells / Q000187:drug effects / Q000502:physiology*; D013552:Swine
D002352:Carrier Proteins; D006063:Chorionic Gonadotropin; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone