In vitro regulation of rat Sertoli cell transferrin expression by tumor necrosis factor α and retinoic acid

Abstract

In the present study, we examined the in vitro regulation of 20-day-old rat Sertoli cell transferrin expression by tumor necrosis factor α (TNF α), a paracrine factor produced by germ cells. Addition of TNF α to highly purified cultured Sertoli cells resulted in a dose and time-dependent enhancement in the levels of transferrin mRNA (Northern-blot) and protein (RadioImmunoAssay) with an ED 50 of 120pM. Co-treatment of Sertoli cells with the optimal dose of retinoic acid (RA, a potent inducer of transferrin) and TNF α induced a stimulation of transferrin that was significantly higher than the FIRT combination, a well known mixture of transferrin activators. Actinomycin D inhibited the effects of TNF α and of RA, suggesting that ongoing RNA synthesis was required to enhance transferrinn. We next demonstrated that RA and TNF α exerted additive effects on transferrin expression as assessed by dose-response and kinetics studies. Moreover pre-treatment with RA, while greatly increasing the amount of transferrin produced, did not modify Sertoli cell responsiveness to TNF α. Together these results show that TNF α and RA are likely to act independently, additively and at least at the transcriptional level to increase transferrin expression.