AUTOCRINE ROLE OF TGF-BETA-1 IN ADRENAL

Three main criteria are required to postulate that a factor has an aut ocrine action in any cell: presence of receptors and biological effect s of the factor; local production which must be regulated by physiolog ical signals and the inhibition of its secretion or action should caus e effects opposite to those caused by the exogenous factor. In adrenal cells, transforming growth factor beta 1 (TGF beta 1) fulfilled these criteria: 1) Adrenal cells possess TGF beta 1 receptors and this fact or regulates the expression of adrenal cell specific genes, including ACTH and angiotensin II (AngII) receptors and several steroidogenic en zymes, leading to changes in the steroidogenic responsiveness; 2) Adre nal cells express and secrete TGF beta 1 and its secretion is regulate d by the two adrenal specific hormones ACTH and AngII; 3) The blockade of TGF beta 1 protein synthesis by an antisense oligonucleotide produ ces changes in adrenal cell functions opposed to those induced by the exogenous factor.