Testicular expression of the TGF-B1 system and the control of Leydig cell proliferation

Abstract

Transforming growth factor beta 1 (TGF-beta1) is a key regulator that modulates male reproductive function. Testicular TGF-beta1 modulates the steroidogenesis of Leydig cells, the organization of peritubular myoid cells, testis development and spermatogenesis. Several studies have indicated that TGF-beta1 is involved in the tight balance between proliferative and apoptotic re- sponses in the Leydig cells. In the present review, we summarize the direct effects of this cytokine in Ley- dig cells under normal and pathological conditions. We analyze the effect of TGF-beta1 in Leydig cells de- pending on the type of receptors involved in the sig- naling pathway of TGF-beta1. Our group has been ana- lyzing the canonical and non canonical intracellular signaling pathways of TGF-beta1 that are involved in the expression of proliferative and apoptotic markers in Leydig cells. On the basis of our studies and from those of other authors we conclude that the balance between the expression of TGF-beta1 receptors and co receptors is of relevance in Leydig cell physiology and pathophisiology.