Abstract
BackgroundPost-spermiogenesis membrane surface modifications rely on molecules present in the reproductive tracts. Two isoforms (isoform 1 and 2) from Quiescin Q6-Sulfydryl Oxidase protein family have been identified in the male reproductive tract of rodent species. However, unlike isoform 1, scarce information is available for isoform 2, likely due to its lower expression level and lack of proper purification methods to obtain sufficient protein quantity for further assays.ResultsThis study demonstrated the presence of short and long forms of Quiescin Q6-Sulfydryl Oxidase 2 in boar, likely representing the secretory (short form) and transmembrane (long form) forms of Quiescin Q6-Sulfydryl Oxidase 2. Immunohistochemistry studies revealed the presence of Quiescin Q6-Sulfydryl Oxidase 2 in a broad range of porcine tissues; the pronounced vesicle-contained Quiescin Q6-Sulfydryl Oxidase 2 at the apical region of epididymis and seminal vesicles epithelium suggested its involvement in sperm physiology and its participation in semen formation. The majority of porcine Quiescin Q6-Sulfydryl Oxidase 2 could be purified via either antibody affinity column or be salted out using 10%–40% ammonium sulfate. Higher amount of low molecular weight Quiescin Q6-Sulfydryl Oxidase 2 observed in the seminal vesicle likely represents the secretory form of Quiescin Q6-Sulfydryl Oxidase 2 and reflects an exuberant secretory activity in this organ.ConclusionsWe demonstrated for the first time, the presence of Quiescin Q6-Sulfydryl Oxidase 2 in porcine species; moreover, two forms of Quiescin Q6-Sulfydryl Oxidase 2 were identified and exhibited distinct molecular weights and properties during protein purification processes. This study also provided feasible Quiescin Q6-Sulfydryl Oxidase 2 purification methods from slaughterhouse materials that could potentially allow obtaining sufficient amount of Quiescin Q6-Sulfydryl Oxidase 2 for future functional investigations.
Highlights
Post-spermiogenesis membrane surface modifications rely on molecules present in the reproductive tracts
Our results demonstrated that Q6-Sulfydryl Oxidase 2 (QSOX2) was present in most of the tissues tested including in heart, lung, liver, spleen, small intestine and kidney
In line with previous reports from rodents or human, no signal can be detected in skeletal muscle; unlike in humans, we observed a positive signal in porcine heart (Fig. 1a), even though its expression level is low
Summary
Post-spermiogenesis membrane surface modifications rely on molecules present in the reproductive tracts. Two isoforms (isoform 1 and 2) from Quiescin Q6-Sulfydryl Oxidase protein family have been identified in the male reproductive tract of rodent species. Kuo et al BMC Veterinary Research (2017) 13:205 acid compositions as well as their immunoreactivity, and adenylate cyclase activity [5]. Many of these processes are thought to improve the structural integrity of the sperm membrane and to increase or to regulate the fertilization ability of the spermatozoa. QSOX protein was first discovered by Otrowoski and co-workers from rat seminal vesicles back in 1979 [6] It was characterized as a flavoprotein responsible for converting sulfhydryl containing substances to corresponding disulfides at the expense of molecular oxygen and generating hydrogen peroxidase as shown in equation: 2R–SH + O2→ R-S = S-R + H2O2 [6]
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