Expression and regulation of transforming growth factor beta 1 mRNA and protein in rat fetal testis in vitro

The expression and secretion of Transforming Growth Factor beta 1 (TGF beta 1) by cultured testes of day 20.5 rat fetuses were investigated. The testes were found to express two TGF beta 1 mRNA transcripts of 2.5 and 1.8 kb. By using mink lung epithelial cell bioassay based on the measurement of the inhibition of tritiated thymidine incorporation in response to TGF beta 1 immunoreactive material, the fetal testes were shown to secrete TGF beta 1 protein in organ culture. This secretion was positively regulated by dibutyryl cyclic AMP or by LH and FSH together, but not by LH alone and very slightly by FSH alone, which suggests interactions between Leydig and Sertoli cells for the control of TGF beta 1 production. These regulations probably take place at a posttranscriptional step since no concomitant increase of TGF beta 1 mRNA levels was observed, Such a positive regulation of TGF beta 1 secretion by gonadotropins could be a characteristic of the rat fetal testis. (C) 1997 Academic Press.