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  • Title: Effects of transforming growth factor beta on ovine adrenocortical cells.
    Author: Rainey WE, Viard I, Mason JI, Cochet C, Chambaz EM, Saez JM.
    Journal: Mol Cell Endocrinol; 1988 Dec; 60(2-3):189-98. PubMed ID: 2850957.
    Abstract:
    Transforming growth factor beta (TGF beta) is a potent regulator of steroidogenic cell function. However, the mechanisms of the effects are not well understood. We studied the actions of TGF beta on primary cultures of ovine adrenocortical (OAC) cells. OAC cells had high affinity receptors for TGF beta (KD congruent to 7.6 +/- 1.5 X 16(-11) M). In addition, TGF beta inhibited the following markers of adrenocortical function: (1) ACTH, cholera toxin and forskolin acute stimulation of cAMP and steroid production; (2) the acute 8-bromo-cAMP stimulation of corticosteroid and pregnenolone production; and (3) the activity and amount of P-450 17 alpha-hydroxylase protein as well as activities of 11 beta- and 21-hydroxylases. The inhibitory effects of TGF beta on ACTH-induced cAMP and steroid production were time (half inhibition at 6 and 3 h respectively) and dose dependent (ID50 congruent to 10(-12) M). From these data we concluded that TGF beta acted rapidly on sites of OAC cell acute responses to stimulation by ACTH before and after the production of cAMP. Pregnenolone production in these cells was not inhibited by TGF beta when steroid production was stimulated on the addition of the readily permeable cholesterol derivative, 22 R-hydroxycholesterol. Thus, the rapid effect on OAC cells was manifest by TGF beta action on the utilization of cellular pools of cholesterol for the acute stimulation of steroid formation and not by direct action on the cholesterol side-chain cleavage enzyme. In addition, cells stimulated with ACTH in the absence or presence of lipoproteins (for up to 36 h) were susceptible to the inhibitory action of TGF beta. Taken together, these data amplify the pleiotropic actions of TGF beta on adrenocortical cell function and demonstrate that one acute action of TGF beta is on the utilization of endogenous supplies of cholesterol for steroid production.
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