TISSUE AND DEVELOPMENTAL DISTRIBUTION, DEPENDENCE UPON TESTICULAR FACTORS AND ATTACHMENT TO SPERMATOZOA OF GPX5, A MURINE EPIDIDYMIS-SPECIFIC GLUTATHIONE-PEROXIDASE

Using immunohistochemistry and Western blotting analyses, we present a detailed study of the distribution of the glutathione peroxidase prot ein (GPX5) within the mouse epididymis. We have shown that the express ion of the epididymis-specific protein is restricted to the caput and essentially localized to the apical cell border of the caput epitheliu m. Secretion of the protein was detected as early as the proximal segm ent of the caput and GPX5 was subsequently found in the lumen of corpu s and cauda epididymis duct. Within the caput, Western blot analyses h ave shown that equivalent quantities of GPX5 protein were found in seg ments I, II, and III. During ontogenesis, GPX5 appeared at 20 days pos tnatal, before the completion of the morphological differentiation of the caput and concomitantly with the appearance of spermatozoa within the epididymis, in agreement with what was reported earlier regarding the transcription of its corresponding gene during epididymal ontogene sis (Faure et al., 1991). Hormonal privation by castration abolished t he accumulation of the GPX5 protein confirming previous data obtained on GPX5 mRNA levels. Treatments such as testosterone replacement or he micastration led to the restriction of the protein to the caput epithe lium, suggesting that protein secretion partly depends both on the pre sence of testicular factors and on spermatozoa. Using electron microsc opy, we have shown that the secreted protein binds to spermatozoa and is found predominantly on the sperm acrosomic region. Finally, we repo rt here that the GPX5 protein can be detected in fluids recovered from the uterine horns of freshly mated female mice. These results suggest that GPX5 might play an important role in sperm maturation from the e arly events up to the onset of fertilization and therefore could poten tially be used as a tool to monitor sperm quality. (C) 1997 Wiley-Liss , Inc.