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

Abstract

A differential library screening procedure was used to clone a novel abundant and tissue-specific cDNA from the dog epididymis. It was tentatively named CE7 for dog epididymal gene product 7. By sequence similarity to homologous counterparts expressed in mice, rats, pigs, and macaque monkeys, it appears that the 1.5 kb dog epididymal mRNA encodes the secretory glutathione peroxidase-like protein, GPX5. This protein is very similar to the family of glutathione peroxidase enzymes, but does not contain selenocysteine. Northern blot and in situ hybridization analyses revealed that the mRNA encoding CE7/GPX5, like its species homologues, was restricted to the epididymis and transcribed by the epithelial cells in the proximal parts of the organ. While the CE7 cDNA probe cross-hybridized to epididymal mRNAs in most species included in this study, it failed to identify a human GPX5 counterpart. Northern blot analyses of epididymal RNA extracts from hemi-cryptorchid dogs suggested that testicular secretions, including androgen hormones, temperature effects, or both, were involved in the region-dependent modulation of mRNA encoding CE7 in the dog epididymis. The effect was most obvious in the caput region of the abdominal organ where the mRNA encoding CE7 was almost completely downregulated.

Molecular characterization of epididymal proteins

“…One difficulty of this 'gene-specific' library screening approach lies in the high degree of species specificity, that is, poor evolutionary conservation of many epididymal proteins. In addition, there are considerable species differences in the protein content of the epididymal fluid in various mammals (Beiglböck et al, 1998), although at least the most abundant proteins do appear to be shared.…”

A Putative 12‐Transmembrane Domain Cotransporter Associated With Apical Membranes of the Epididymal Duct

“…A canine epididymal cDNA library constructed in the Lambda UniZAP‐XR vector (Stratagene, LaJolla, Calif; Ellerbrock et al, 1994) was screened employing a hybridization strategy essentially as previously described (Beiglböck et al, 1998). Briefly, approximately 10 000 independent cDNA clones were plated at low density (approximately 500 plaque‐forming units per plate) and screened by a multistep procedure employing 32 P‐radiolabeled single‐stranded cDNA pools from canine epididymis to provide positively hybridizing signals and from liver, testis, and lung as negative controls.…”

Proteins of the canine seminal plasma

“…Similar to bulls (MOURA et al, Ciência Rural, v.46, n.5, mai, 2016. 2010), some evidence suggests that GPx is present in canine epididymal secretions (BEIGLBOCK et al, 1998), and a greater activity of this enzyme was reported in samples collected from the cauda of the epididymis than in samples collected from the other segments (caput and corpus) and in the three ejaculated fractions. Therefore, this result indicates that the epididymis may be the main source of GPx in canine semen (ANGRIMANI et al, 2014b).…”