[Demonstration of the secretion of IGF-I and of its binding proteins by bovine adrenal fasciculata cells in culture. Immunocytochemistry, radioimmunoassay and ligand blotting].
Insulin-like growth factor I (IGF-I) is required for the maintenance of differentiated functions of bovine adrenal fasciculata cells in culture. We have investigated, by immunocytochemistry, the presence of IGF-I in cells cultured in the absence or presence of corticotropin (ACTH) and angiotensin II (A-II), as well as the secretion of IFG-I and its binding proteins (IGF-BP). In control cultures, very few cells were specifically stained with the anti-IGF-I serum. Following 2 days treatment with A-II (10(-6)M) or ACTH (10(-8)M) the number of stained cells increased 5 and 14 fold, respectively. In all cases the staining was specific since it was abolished when non-immune rabbit serum replaced the anti-IGF serum or when the anti-IGF-I serum was preincubated with saturating concentrations of the peptide. Under the same experimental conditions the secretion of IGF-I in the medium, evaluated by a specific radioimmunoassay, was increased 2- and 7-fold by A-II and ACTH, respectively. Using the method of western ligand blot, we found that the major form of IGF-BP secreted by control adrenal cells is a 38-42 kDa doublet protein. Two minor forms with apparent mol wt of 28-31 kDa and 24 kDa have also been identified. Following acid-ethanol extraction of the conditioned medium all the IGF-BP were recovered in the pellet, whereas most of the IGF-I was in the supernatant. ACTH and, to a lesser extent.(ABSTRACT TRUNCATED AT 250 WORDS)
Penhoat
A
A
INSERM U.307, Hôpital Debrousse, Lyon.
Leduque
P
P
Jaillard
C
C
Chatelain
P G
PG
Dubois
P M
PM
Saez
J M
JM
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D015151:Immunoblotting; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism*; D008024:Ligands; D011863:Radioimmunoassay; D013002:Somatomedins / Q000032:analysis / Q000378:metabolism*; D015383:Zona Fasciculata / Q000166:cytology / Q000378:metabolism*
D002352:Carrier Proteins; D008024:Ligands; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I
Mise en évidence de la sécrétion d'IGF-I et de ses protéines de liaison par les cellules fasciculées du cortex surrénalien bovin en culture. Immunocytochimie, dosage radioimmunologique et "ligand blotting".