TGF-BETA (TRANSFORMING GROWTH-FACTOR-BETA ) AND ITS RELATED PEPTIDES IN THE TESTIS

Recent data on TGFbeta (and related peptides) expression and action in the testis are briefly reviewed. At least, three isoforms of TGFbeta are expressed during the male gonadal development. TGFbeta are express ed in somatic and germ cells. The expression of the different isoforms varies during gonadal development and is cell specific. Both types I, II and III TGFbeta receptors have been localized in somatic cells. TG Fbeta inhibits gonadotropin action both in Sertoli cells and Leydig ce lls as well as proliferation of germ cells and Leydig cells. Inhibins and activins (in terms of mRNA and proteins) are expressed in somatic cells and germ cells. Inhibin production in Sertoli cells is under the control of FSH, local factors (ex: EGF, insulin, opiods) and probably of germ cells. Activins and inhibins regulate Leydig and Sertoli cell s activities and germ cells development. The existence of activin rece ptors in somatic and germ cells has been suggested by the presence of type II receptor mRNA (ActRII and ActRIIB).