Tissue and developmental distribution, dependence upon testicular factors and attachment to spermatozoa of GPX5, a murine epididymis-specific glutathione peroxidase

Abstract

Using immunohistochemistry and Western blotting analyses, we present a detailed study of the distribution of the glutathione peroxidase protein (GPX5) within the mouse epididymis. We have shown that the expression of the epididymis‐specific protein is restricted to the caput and essentially localized to the apical cell border of the caput epithelium. Secretion of the protein was detected as early as the proximal segment of the caput and GPX5 was subsequently found in the lumen of corpus and cauda epididymis duct. Within the caput, Western blot analyses have shown that equivalent quantities of GPX5 protein were found in segments, I, II, and III. During ontogenesis, GPX5 appeared at 20 days postnatal, 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 ontogenesis (Faure et al., 1991). Hormonal privation by castration abolished the accumulation of the GPX5 protein confirming previous data obtained on GPX5 mRNA levels. Treatments such as testosterone replacement or hemi‐castration led to the restriction of the protein to the caput epithelium, suggesting that protein secretion partly depends both on the presence of testicular factors and on spermatazoa. Using electron microscopy, we have shown that the secreted protein binds to spermatozoa and is found predominantly on the sperm acrosomic region. Finally, we report here that the GPX5 protein can be detected in fluids recovered from the uterinie horns of freshly mated female mice. These results suggest that GPX5 might play an important role in sperm maturation from the early events up to the onset of fertilization and therefore could potentially be used as a tool to monitor sperm quality. Mol. Reprod. Dev. 47:87–98, 1997. © 1997 Wiley‐Liss, Inc.

Expression of selenium-independent glutathione peroxidase 5 (GPx5) in the epididymis of Small Tail Han sheep

“…GPx5 was secreted to the epididymal lumen, where it binds to the transiting sperm and protects it from ROS damage. This result is similar to a series of studies in mice [ 12 , 29 , 30 ]. In our study, the proximal and distal sheep caput showed a positive signal, but the GPx5 protein signal in the distal was stronger than the proximal caput; a result which is also similar to a mouse study [ 9 ].…”

Dog epididymis-specific mRNA encoding secretory glutathione peroxidase-like protein

“…However, expression of mRNA encoding GPX3 is equally strong in the lung, testis and ovary (Maser et al, 1994) which were all negative for the mRNA encoding CE7/GPX5. Expression of mRNA encoding CE7 along the dog epididy¬ mal duct was in accordance with that observed for mRNA encoding GPX5 in other species (Faure et al, 1991;Syntin et al, 1996;Vernet et al, 1997), the vast majority being expressed in the caput region. The interspecies conservation of this regionalized expression suggests that a conserved regulatory transcriptional mechanism may be involved.…”

The PEA3 protein of theEts oncogene family is a putative transcriptional modulator of the mouse epididymis-specific glutathione peroxidase genegpx5

“…Moreover, we have observed that within the epididymis both PEA3 and gpx5 mRNAs were confined to the same territory, the caput epididymidis. Furthermore, data from Western blot analyses (not shown) have suggested that the PEA3 protein is mostly localized within the initial segment of the caput epididymidis, matching the epididymal territory expressing the gpx5 gene (Faure et al, 1991;Vernet et al, 1997). Altogether, these data are in agreement with the hypothesis that the PEA3 factor might act as a positive transcriptional modulator of gpx5 expression.…”