Transforming growth factor ?1 and adrenocorticortropin differentially regulate the synthesis of adrenocortical cell heparan sulfate proteoglycans and their binding of basic fibroblast growth factor

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Abstract
Adrenocortical differentiated functions are under the control of both endocrine hormones such as ACTH and local factors such as transforming growth factor β (TGFβ) or basic fibroblast growth factor (bFGF). Besides their regulatory actions on the synthesis of corticosteroids, these two classes of factors also exert some important effects on the cellular environment. We have examined here the regulation by ACTH and TGFβ of adrenocortical cell proteoglycan synthesis and secretion. Under basal conditions, adrenocortical cells synthesized and secreted several species of sulfated proteoglycans, 80% of them being recovered in solution in the culture medium. When analyzed by ion exchange chromatography, the cell extracts and the media from cells metabolically labeled with 35S‐suifate were found to contain two and three species of radioactive sulfated proteoglycans, respectively. All species were proteoheparan‐sulfates. Treatment of adrenocortical cells with TGFβ1 or ACTH resulted in a significant increase of the incorporation of 35S into both secreted and cell‐associated proteoglycans. ACTH stimulated more than three times the amount of secreted proteoglycans eluting from DEAE‐Trisacryl as peak B, whereas TGFβ preferentially increased the amount of peak C. No important modification of the size of the synthesized proteoglycans was observed. The subpopulation of heparan sulfate proteoglycans capable to bind bFGF was also largely increased after ACTH or TGFβ treatment and paralleled the variation in overall proteoheparan sulfate synthesis. Thus those effects of TGFβ and ACTH on proteoglycan synthesis may participate in an increased ability of adrenocortical cells to bind and respond to bFGF.

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