Expression of Fas system-related genes in the testis during development and after toxicant exposure

The Fas system has been identified as a key regulator of testicular germ ce ll apoptosis. The goal of these experiments was to explore the expression o f Fas system-related genes in the testis during development and after toxic ant exposure. Both Fas ligand (FasL) and Fas receptor (Fas) were expressed postnatally in rat testis with peak expression associated with the high lev els of germ cell apoptosis found during the first wave of spermatogenesis. The testicular expression of RIP and FAP-1, components of the Pas activatin g complex, increased after exposure to mono-(2-ethylhexyl)phthalate (MEHP), a Sertoli cell toxicant which induces massive germ cell death. Finally, th e expression of additional apoptosis-inducing genes, including tumor necros is factor receptor (TNFR), FADD, TRAIL, and DR5, was detected in mammalian testis. These results provide additional support for the following concepts : (1) Sertoli-germ cell interactions are important in the control of germ c ell apoptosis; and (2) the Fas system and similar paracrine systems are imp ortant modulators of testicular homeostasis. (C) 1998 Elsevier Science Irel and Ltd. All rights reserved.