Transforming growth factor-beta 1 stimulates fibronectin production in bovine adrenocortical cells in culture.

Transforming growth factor-beta (TGF-beta 1) suppresses cortisol production when added to cultured bovine adrenocortical (BAC) cells while concomitantly increasing fibronectin synthesis and assembly into extracellular fibrils. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of gelatin-Sepharose-treated media from BAC cells demonstrated a 2-fold stimulation of fibronectin production by TGF-beta 1 in both the presence and absence of serum. Indirect immunofluorescence studies revealed that TGF-beta 1 caused a striking increase in the fibronectin content of BAC extracellular matrix. TGF-beta 1 caused a 4-fold increase in deoxycholate-insoluble fibronectin after 12 h and a 7-fold increase after 24 h over that of control BAC cultures. Northern hybridization analyses indicated that TGF-beta 1 stimulated levels of fibronectin poly(A)+ RNA 2.3-fold. We found that cultured BAC cells express TGF-beta 1 mRNA, suggesting a possible autocrine role for TGF-beta 1 in the adrenal.