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(111) PROTEIN C INHIBITOR EXPRESSION BY MATURE RAT SERTOLI CELLS: EFFECTS OF TESTOSTERONE WITHDRAWAL AND REPLETION. Anway, Matthew1, Fulmer, Janet1, Zirkin, Barry1, 1 Dept of Biochemistry and Molecular Biology, Baltimore, MD ABSTRACT- Protein C inhibitor (PCI), a member of the plasma serine protease inhibitor (serpin) family, is abundantly expressed by the male reproductive tract, including seminal vesicle and testis. Mice lacking PCI are infertile due to impaired spermatogenesis. In the testis, PCI is expressed specifically by Sertoli cells. The objective of this study was to determine whether PCI expression by adult Sertoli cells is testosterone (T) dependent. We analyzed PCI expression in Sertoli cells that were freshly isolated from adult rats that had been treated with LH suppressive testosterone/estradiol (TE) implants, a procedure that decreases intratesticular testosterone, and by Sertoli cells isolated from rats that had received implants for 8 weeks and then a replacement dose of T (24 cm T implant) for 5 days. Adult Sertoli cells were isolated from individual testes rapidly (<4 hours), with >80 percent purity; the Sertoli cell preparations did not express hemiferrin and protamine 2, both of which are germ cell genes, but did express the unique Sertoli cell expressed genes SGP2 and transferrin. As determined by Northern blot analyses, PCI gene expression by adult Sertoli cells decreased by 50 percent and 60 percent from wild type control levels at 4 and 8 weeks, respectively, postimplantation. Decrease in PCI expression paralleled decrease in intratesticular T as well as testis weight ( KEY WORDS: sertoli cells, protein c inhibitor, protease, testosterone implants |
50 percent), suggesting that PCI responds to T reduction, germ cell loss, or both. Within 5 days of providing replacement T to rats that had received TE implants for 8 weeks, a 25 percent increase in PCI gene expression was seen without a significant increase in testis weight. Thus, the isolation procedure that we used made it possible to treat adult Sertoli cells in vivo and then assess treatment effects in vitro without subjecting the cells to culture conditions. The data suggest that PCI gene expression by mature Sertoli cells may be responsive to T alone or to both T and germ cells. (Supported by NIH grant HD36209).