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

In the present study, we examined the in vitro regulation of 20-day-old rat Sertoli cell transferrin expression by tumor necrosis factor alpha (TNF al pha), a paracrine factor produced by germ cells. Addition of TNF alpha to h ighly 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 ED50 of 120pM. Go-treatment of Sertoli cells wit h the optimal dose of retinoic acid (RA, a potent inducer of transferrin) a nd TNF alpha induced a stimulation of transferrin that was significantly hi gher than the FIRT combination, a well known mixture of transferrin activat ors. Actinomycin D inhibited the effects of TNF alpha and of RA, suggesting that ongoing RNA synthesis was required to enhance transferrinn. We next d emonstrated that RA and TNF alpha exerted additive effects on transferrin e xpression as assessed by dose-response and kinetics studies. Moreover pre-t reatment with RA, while greatly increasing the amount of transferrin produc ed, did not modify Sertoli cell responsiveness to TNF alpha. Together these results show that TNF alpha and RA are likely to act independently, additi vely and at least at the transcriptional level to increase transferrin expr ession. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.