GPX5 is present in the mouse caput and cauda epididymidis lumen at three different locations

Abstract

In mice, GPX5 is a secreted protein abundantly synthesized by the caput epididymidis. The protein is secreted as early as the initial segment of the caput and is found subsequently associated with the sperm plasma membrane in a sub-acrosomic localization. We show here that GPX5 is present in the caput and cauda epididymides lumens in three different locations: either free as a soluble protein in the caput epididymal fluid, weakly bound to caput sperm membranes, or, finally, associated to lipid-containing structures conferring to the protein a protective effect against proteolytic digestions. Within the cauda epididymidis, the amount of free GPX5 is low compared to the caput and the association with sperm membranes proved to be more solid. In both caput and cauda sperm samples, the association of GPX5 with the sperm membrane protects GPX5 from proteolytic cleavages. Protection against proteolytic digestions can be overcome by physical treatments of epididymal fluid and sperm samples such as ultrasounds or very acidic pH. These data suggest that complex phenomena and structures participate in the transfer and binding of the caput-secreted GPX5 protein to the sperm plasma membrane.

Antioxidant enzyme expression of mRNA and protein in the epididymis of finasteride-treated male rat offspring during postnatal development

“…The results of this study confirm the changes in antioxidant enzyme expression of mRNA and proteins during postnatal maturation, being different in immature rats (PND 7,14,21,28) than in mature animals (PND 90), in agreement with other reports [62] that demonstrated changes in antioxidant enzymes' (GPX, GR, CAT, SOD) activity in male reproductive tissues (such as the cauda epididymidis) in young (4-month-old) rats when compared to older (21-month-old) rats. Some authors [16] consider CAT one of the most controversial enzymes within the epididymis, such as when CAT mRNA expression is extremely low, undermining its potential role as a major antioxidant in the tissue.…”

“…Therefore, increased attention has been paid to the epididymis as a supportive organ protecting male reproductive cells against oxidative stress [16], and a rich source of antioxidant enzymes, e.g. catalase (CAT), superoxide dismutase (SOD), and enzymes associated with glutathione peroxidation and reduction, such as glutathione peroxidase (GPX) [16,[20][21][22][23][24][25][26][27][28] and glutathione reductase (GR) [29].…”

Epididymosomes, prostasomes, and liposomes: their roles in mammalian male reproductive physiology

“…Glutathione peroxidase 5 (GPX5) is another protein associated with epididymosomes in murine species (Rejraji et al 2002). GPX5 is a seleno-independent GPX protecting sperm from oxidative stress, including preserving their DNA integrity (Chabory et al 2009).…”

Epididymis seleno-independent glutathione peroxidase 5 maintains sperm DNA integrity in mice

“…This unconventional mammalian GPX, unlike the other members of the family, is devoid of the classical selenocysteine residue that was shown to be critical for its activity (5). Gpx5 is strongly expressed under androgenic control in the caput epididymidis (6), and the corresponding protein is readily secreted in the epididymal lumen, where it was shown to interact loosely with sperm cells (7,8). These expression characteristics were found to be quite conserved in all the mammals tested so far, including humans, suggesting that this enzyme might play a key role in the process of post-testicular sperm maturation.…”