Sertoli cell-germ cell interactions and TGF beta 1 expression and secretion in vitro

Transforming growth factor beta 1 (TGF beta 1) has been reported to be secreted and to act within the somatic cells of the testis. We examined whether the TGF beta 1 expression is present at mRNA and protein levels in purified rat Sertoli cells (SC), purified pachytene spermatocytes (SPC), and early spermatids (SPT) cultured alone or together. SC expressed a single TGF beta 1 transcript of 2.5 kb, but no TGF beta 1 protein could be detected in SC conditioned medium indicating that, if at all, SC secreted less than 10 pg/10(6) cells/24 h. Neither TGF beta 1 mRNA nor protein could be detected in either SPC or SPT. Coculture of SC with either SPC or SPT resulted in a 2-fold increase of TGF beta 1 mRNA and more importantly in the secretion of TGF beta 1 protein. These findings demonstrate that Sertoli cell-germ cell interactions regulate TGF beta 1 expression and secretion and indicate that TGF beta 1 may be involved in spermatogenesis.