TGFβ1 effects on functional activity of porcine thyroid cells cultured in suspension

Thyrotropin (TSH) and transforming growth factor (TGFbeta(1)) have major roles in the regulation of folliculo-genesis and differentiation in thyroid cells. Isolated porcine thyroid cells cultured in the presence of TSH on a plastic surface recover a follicular architecture and exhibit normal functional properties. The addition of TGFbeta(1) to the culture medium induces important morphological changes and extracellular matrix remodelling. Similarly, thyroid cells lose their ability to organify iodine and their responsiveness to adenylate cyclase. The aim of this study was to analyse the influence of TGFbeta(1) on the Functional activity of thyrocytes in suspension culture, independent of follicle disruption. In this system, we demonstrate that TGFbeta(1) inhibits expression of thyroperoxidase, NADPH oxidase activity, iodine uptake and, consequently, iodine organification. Moreover, TGFbeta(1) decreases basal and TSH-stimulated cAMP production and TSH receptor expression. Taken together, these data converge to demonstrate in essential role of TGFbeta(1) in the regulation of the thyroid cell function.