THE GENE ENCODING VITAMIN-K-DEPENDENT ANTICOAGULANT PROTEIN-C IS EXPRESSED IN HUMAN MALE REPRODUCTIVE TISSUES

Protein C is a vitamin K-dependent protein circulating in plasma as a zymogen to an anticoagulant serine protease, After its activation, pro tein C cleaves and inactivates coagulation factors Va and VIIIa. Human protein C is synthesized in liver and undergoes extensive post-transl ational modification during its synthesis, Recently, the protein C inh ibitor was demonstrated to be synthesized in several organs of the hum an male reproductive tract, Moreover, vitamin K-dependent protein S, w hich functions as a co-factor to activated protein C, was found to be synthesized in the Leydig cells of human testis. The aim of this study was to elucidate whether the protein C gene is also expressed in the male reproductive system, Specific immunostaining of protein C was fou nd in Leydig cells of human testis, in the excretory epithelium of epi didymis, and in some epithelial glands of the prostate, whereas no imm unostaining was detected in seminal vesicles, Northern blotting and no n-radioactive in situ hybridization demonstrated protein C mRNA in Ley dig cells, in the excretory epithelium of epididymis, and in some of t he epithelial glands of the prostate. The mRNA was distributed perinuc learly and the localization was in accordance with the specific immuno staining for protein C, The epithelium of epididymis was also found to contain both protein S mRNA and immunoreactivity. The demonstration o f both protein C and protein S immunoreactivities, as well as their mR NAs, in male reproductive tissues suggests as yet unknown local functi ons for these proteins.