Transforming growth factor-β effects on morphology of immature rat Leydig cells

Transforming growth factor-beta (TGFbeta) has been shown to regulate steroid production and DNA synthesis in rat Leydig cells. We have investigated the effects of TGFbeta on the secretion of extracellular matrix (ECM) proteins and on the cytoskeleton of immature rat Leydig cells in vitro. TGFbeta caused significant morphological changes in Leydig cells, which were accompanied by significant increases in secretion of fibronectin, laminin and collagen IV and rearrangement of actin filaments in TGFbeta-treated cells. The cells cultured on plates pre-coated with fibronectin or fibronectin plus laminin and collagen IV, displayed morphological and cytoskeletal changes similar to those induced by TGFbeta. Immunofluorescence localization studies revealed significantly higher fibronectin staining in Leydig cells in adult animals and in LH-treated immature animals than those in untreated immature animals. We conclude that TGFbeta participates in the morphological differentiation of immature Leydig cells into adult Leydig cells in the rat testis by inducing the expression of ECM proteins. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.