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

Amniotic Mesenchymal-Derived Extracellular Vesicles and Their Role in the Prevention of Persistent Post-Breeding Induced Endometritis

Persistent post-breeding induced endometritis (PPBIE) is considered a major cause of subfertility in mares. It consists of persistent or delayed uterine inflammation in susceptible mares. There are many options for the treatment of PPBIE, but in this study, a novel approach aimed at preventing the onset of PPBIE was investigated. Stallion semen was supplemented with extracellular vesicles derived from amniotic mesenchymal stromal cells (AMSC-EVs) at the time of insemination to prevent or limit the development of PPBIE. Before use in mares, a dose–response curve was produced to evaluate the effect of AMSC-EVs on spermatozoa, and an optimal concentration of 400 × 106 EVs with 10 × 106 spermatozoa/mL was identified. At this concentration, sperm mobility parameters were not negatively affected. Sixteen susceptible mares were enrolled and inseminated with semen (n = 8; control group) or with semen supplemented with EVs (n = 8; EV group). The supplementation of AMSC-EVs to semen resulted in a reduction in polymorphonuclear neutrophil (PMN) infiltration as well as intrauterine fluid accumulation (IUF; p < 0.05). There was a significant reduction in intrauterine cytokine levels (p < 0.05) for TNF-α and IL-6 and an increase in anti-inflammatory IL-10 in mares in the EV group, suggesting successful modulation of the post-insemination inflammatory response. This procedure may be useful for mares susceptible to PPBIE.

Microfluidics facilitating the use of small extracellular vesicles in innovative approaches to male infertility

Sperm are transcriptionally and translationally quiescent and, therefore, rely on the seminal plasma microenvironment for function, survival and fertilization of the oocyte in the oviduct. The male reproductive system influences sperm function via the binding and fusion of secreted epididymal (epididymosomes) and prostatic (prostasomes) small extracellular vesicles (S-EVs) that facilitate the transfer of proteins, lipids and nucleic acids to sperm. Seminal plasma S-EVs have important roles in sperm maturation, immune and oxidative stress protection, capacitation, fertilization and endometrial implantation and receptivity. Supplementing asthenozoospermic samples with normospermic-derived S-EVs can improve sperm motility and S-EV microRNAs can be used to predict non-obstructive azoospermia. Thus, S-EV influence on sperm physiology might have both therapeutic and diagnostic potential; however, the isolation of pure populations of S-EVs from bodily fluids with current conventional methods presents a substantial hurdle. Many conventional techniques lack accuracy, effectiveness, and practicality; yet microfluidic technology has the potential to simplify and improve S-EV isolation and detection.

Essential Protective Role of Catalytically Active Antibodies (Abzymes) with Redox Antioxidant Functions in Animals and Humans

During the life of aerobic organisms, the oxygen resulting from numerous reactions is converted into reactive oxygen species (ROS). Many ROS are dangerous due to their high reactivity; they are strong oxidants, and react with various cell components, leading to their damage. To protect against ROS overproduction, enzymatic and non-enzymatic systems are evolved in aerobic cells. Several known non-enzymatic antioxidants have a relatively low specific antioxidant activity. Superoxide dismutases, catalase, glutathione peroxidase, glutathione S-transferase, thioredoxin, and the peroxiredoxin families are the most important enzyme antioxidants. Artificial antibodies catalyzing redox reactions using different approaches have been created. During the past several decades, it has been shown that the blood and various biological fluids of humans and animals contain natural antibodies that catalyze different redox reactions, such as classical enzymes. This review, for the first time, summarizes data on existing non-enzymatic antioxidants, canonical enzymes, and artificial or natural antibodies (abzymes) with redox functions. Comparing abzymes with superoxide dismutase, catalase, peroxide-dependent peroxidase, and H₂O₂-independent oxidoreductase activities with the same activities as classical enzymes was carried out. The features of abzymes with the redox activities are described, including their exceptional diversity in the optimal pH values, dependency and independence on various metal ions, and the reaction rate constants for healthy donors and patients with different autoimmune diseases. The entire body of evidence indicates that abzymes with redox antioxidant activities existing in the blood for a long time compared to enzymes are an essential part of the protection system of humans and animals from oxidative stress.

Epididymosomes: A potential male fertility influencer

During transit and storage in epididymis, spermatozoa undergo final maturation, acquire motility, functional competence and the ability to fertilise an oocyte. Epididymal secretions contain a complex biochemical milieu of diverse inorganic ions, proteins, metabolites and other molecules. Since it is believed that spermatozoa are translationally silent, proteins appearing in them are thought to be synthesised elsewhere, including epididymis, and then incorporated to the cells. One of the important mechanisms suggested to be involved in transfer of epididymal secretions to spermatozoa is through exosomes called epididymosomes. Epididymosomes released from the epididymal epithelium contain proteins, noncoding RNAs and distinct set of lipids that are transferred to spermatozoa while they pass through the different epididymal regions. Owing to the importance of these molecules for sperm maturation and fertilising ability, research on epididymosomes has gained increasing attention during the last decade. This review is focused on epididymosomes, with emphasis on recent advances in the understanding of mechanisms of epididymosomal cargo transfer to spermatozoa and potential roles of epididymosomes in sperm function and beyond. Possibilities of utilising the molecular signatures of epididymosomes as a tool for male fertility assessment are also discussed.

Role of Exosomes in the Exchange of Spermatozoa after Leaving the Seminiferous Tubule: A Review

BACKGROUND

Exosomes are extracellular vesicles (EVs) released from cells upon fusion of an intermediate endocytic compartment with the plasma membrane. They refer to the intraluminal vesicles released from the fusion of multivesicular bodies with the plasma membrane. The contents and number of exosomes are related to diseases such as metabolic diseases, cancer and inflammatory diseases. Exosomes have been used in neurological research as a drug delivery tool and also as biomarkers for diseases. Recently, exosomes were observed in the seminal plasma of the one who is asthenozoospermia, which can affect sperm motility and capacitation.

OBJECTIVE

The main objective of this review is to deeply discuss the role of exosomes in spermatozoa after leaving the seminiferous tubule.

METHODS

We conducted an extensive search of the literature available on relationships between exosomes and exosomes in spermatozoa on the bibliographic database.

CONCLUSION

This review thoroughly discussed the role that exosomes play in the exchange of spermatozoa after leaving the seminiferous tubule and its potential as a drug delivery tool and biomarkers for diseases as well.

Exposure to epididymal extracellular vesicles enhances immature sperm function and sustains vitality of cryopreserved spermatozoa in the domestic cat model

PURPOSE

Extracellular vesicles (EVs) secreted by the epididymal epithelium transfer key factors to maturing spermatozoa. Using an in vitro system previously developed in our laboratory, the objective was to (1) characterize the impact of EV exposure on the fertilizing ability and developmental potential of immature sperm cells from the caput epididymidis and (2) examine the benefit of EV exposure to restore vitality of mature spermatozoa from the cauda epididymidis after freezing-thawing.

METHODS

EVs were isolated from entire epididymides and collected into pellets via ultracentrifugation. Immature spermatozoa from adult cats were isolated from the caput epididymis and incubated with EVs prior to in vitro fertilization. Similarly, mature spermatozoa were isolated from the cauda segment and cryopreserved prior to EV exposure and subsequent analysis of motility and developmental potential after fertilization.

RESULTS

EV exposure did not affect the percentage of caput sperm penetration; however, it improved the fertilizing ability (faster pronuclear apposition) and the developmental potential (higher proportions of morula-blastocysts) of those immature sperm cells. While EV exposure was beneficial to the frozen-thawed sperm motility, it did not significantly improve the fertilizing ability and the developmental potential.

CONCLUSIONS

Epididymal EVs contain multiple factors contributing to immature sperm function, specifically enhancing the ability to complete a faster pronuclear apposition with subsequently improved early embryonic development. Supplementation was also beneficial to the motility of spermatozoa that had undergone cryopreservation. Those new findings could lead to new options for male fertility treatment in animal models and humans.

Extracellular vesicles and domestic animal reproduction

Embryo implantation is a complex process in which significant changes occur continually in both the corpora lutea and in the endometrium of females and which varies depending on the embryonic, pre-implantation, or fetal stages. However, at all stages, correct maternal-embryonic communication is essential. In the last few years, a new intercellular communication tool, mediated by extracellular vesicles (EVs), has emerged. Many authors agree on the relevant role of EVs in correct communication between the mother and the embryo, as a fundamental system for the pregnancy to reach term and embryonic development to occur correctly. This review analyzes current information on known EVs, their main functions, and their role in implantation and embryonic development in domestic animals.

Mitochondrial Functionality in Male Fertility: From Spermatogenesis to Fertilization

Mitochondria are structurally and functionally distinct organelles that produce adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS), to provide energy to spermatozoa. They can also produce reactive oxidation species (ROS). While a moderate concentration of ROS is critical for tyrosine phosphorylation in cholesterol efflux, sperm–egg interaction, and fertilization, excessive ROS generation is associated with male infertility. Moreover, mitochondria participate in diverse processes ranging from spermatogenesis to fertilization to regulate male fertility. This review aimed to summarize the roles of mitochondria in male fertility depending on the sperm developmental stage (from male reproductive tract to female reproductive tract). Moreover, mitochondria are also involved in testosterone production, regulation of proton secretion into the lumen to maintain an acidic condition in the epididymis, and sperm DNA condensation during epididymal maturation. We also established the new signaling pathway using previous proteomic data associated with male fertility, to understand the overall role of mitochondria in male fertility. The pathway revealed that male infertility is associated with a loss of mitochondrial proteins in spermatozoa, which induces low sperm motility, reduces OXPHOS activity, and results in male infertility.

The Effects of Antioxidants Provided with Feed on Certain Quality Parameters of Bull Semen Under Heat Stress Conditions

The aim of the current research was to assess the effects of the feed additive made of lyophilised melon juice (source of superoxide dismutase, SOD) and inactivated live Saccharomyces cerevisiae (strain R397) cells added to the feed via the product containing high levels of organically bound selenium (source of selenium-dependant glutathione peroxidase, Se-GPx) on the semen quality of bulls in heat stress conditions. The 15 bulls chosen for the experiment were assigned to three equal groups (control –group C; treated group M, given the source of SOD; and group A, treated with the source of Se-GPx). The research was conducted in summer. The activities of SOD and Se-GPx in seminal plasma were determined spectrophotometrically. Computer-assisted semen analysis was done to determine the sperm counts, motility and velocity. The temperature and humidity were recorded with a digital data logger.

The average SOD activity in the control bulls was significantly lower than in M (p<0.001) and A (p<0.001), whilst the average activities in the treated groups did not differ significantly (p=0.784). Higher average SOD activity compared to the control in the treated groups showed that both feed additives increased the antioxidative capacity of the seminal fluid. The average GPx activity in the control was significantly lower than in groups A (p=0.001) and M (p=0.005), whilst the two treatments did not lead to significantly different results (p=0.701). The analysis of relations between the activity of each enzyme and sperm motility and progressive motility in each of the bulls failed to detect a significant correlation. The analysis of the relation between THI (temperature-humidity index) and the activity of the antioxidative enzymes revealed that the increase in THI coincided with the decrease in the SOD activity in the control group, but with its increase in the treated groups (p>0.05). In all of the three groups with the increase in THI there was an increase in GPx activity (p>0.05). It can be concluded that in all of the three groups of bulls there was an increase in the activity of both enzymes in the seminal plasma, but the increase was significantly lower in the control. Thus, the antioxidative capacity of the seminal plasma of untreated bulls was proven to be lower in comparison with those of the treated animals.

Novel Proteomic Profiling of Epididymal Extracellular Vesicles in the Domestic Cat Reveals Proteins Related to Sequential Sperm Maturation with Differences Observed between Normospermic and Teratospermic Individuals

Extracellular vesicles (EVs) secreted by the epididymal epithelium transfer to spermatozoa key proteins that are essential in promoting motility and subsequent fertilization success. Using the domestic cat model, the objectives were to (1) characterize and compare protein content of EVs between segments of the epididymis, and (2) compare EV protein compositions between normo- and teratospermic individuals (producing >60% of abnormal spermatozoa). Epididymal EVs from adult cats were isolated and assessed via liquid chromatography tandem MS. Both male types shared 3008 proteins in total, with 98 and 20 EV proteins unique to normospermic and teratospermic males, respectively. Expression levels of several proteins changed between epididymal segments in both male types. Several proteins in both groups were related to sperm motility (e.g. hexokinase 1, adenylate kinase isoenzyme) and zona pellucida or oolemma binding (e.g. disintegrin and metalloproteinase domain proteins, zona binding proteins 1 and 2). Interestingly, seven cauda-derived EV proteins trended downward in teratospermic compared with normospermic males, which may relate to poor sperm quality. Collective results revealed, for the first time, EV proteins related to sequential sperm maturation with differences observed between normospermic and teratospermic individuals.

Role of aposomes and epididymosomes in sperm quality control: A light and transmission electron microscopic study in an experimental rat model

The epididymis responds to adverse conditions of misshapen spermatozoa resulting from pathological changes or toxic insults by secretion of a dense matrix that segregates the latter for complete disintegration and dissolution. The objective of this study was to find the source of this matrix and the role-player of disintegration and dissolution of misshapen spermatozoa. We chose Wistar strain male rat model to tackle this issue, and the rats were administered with aflatoxin B1 for 55 days so as to increase the incidence of misshapen spermatozoa. At the end of the treatment, different segments of epididymis were processed for microscopic observations. We found that parallel with abundant misshapen spermatozoa in the epididymis the principal cells of the initial segment secrete enormous membrane-bound apical blebs called aposomes, which contain epididymosomes. The aposomes were found to coalesce so as for the content to merge and form a dense matrix that entangles the misshapen spermatozoa and segregates them from viable spermatozoa. The epididymosomes associate with the misshapen spermatozoa, and the latter is processed to disintegration and total dissolution. Therefore, we assign the role of segregation of misshapen spermatozoa from viable ones to the dense matrix of aposomes and their disintegration and dissolution to the epididymosomes.

Emerging roles for non-selenium containing ER-resident glutathione peroxidases in cell signaling and disease

Maintenance of cellular redox control is pivotal for normal cellular functions and cell fate decisions including cell death. Among the key cellular redox systems in mammals, the glutathione peroxidase (GPX) family of proteins is the largest conferring multifaceted functions and affecting virtually all cellular processes. The endoplasmic reticulum (ER)-resident GPXs, designated as GPX7 and GPX8, are the most recently added members of this family of enzymes. Recent studies have provided exciting insights how both enzymes support critical processes of the ER including oxidative protein folding, maintenance of ER redox control by eliminating H₂O₂, and preventing palmitic acid-induced lipotoxicity. Consequently, numerous pathological conditions, such as neurodegeneration, cancer and metabolic diseases have been linked with altered GPX7 and GPX8 expression. Studies in mice have demonstrated that loss of GPX7 leads to increased differentiation of preadipocytes, increased tumorigenesis and shortened lifespan. By contrast, GPX8 deficiency in mice results in enhanced caspase-4/11 activation and increased endotoxic shock in colitis model. With the increasing recognition that both types of enzymes are dysregulated in various tumor entities in man, we deem a review of the emerging roles played by GPX7 and GPX8 in health and disease development timely and appropriate.

Tetraspanins, More than Markers of Extracellular Vesicles in Reproduction

The participation of extracellular vesicles in many cellular processes, including reproduction, is unquestionable. Although currently, the tetraspanin proteins found in extracellular vesicles are mostly applied as markers, increasing evidence points to their role in extracellular vesicle biogenesis, cargo selection, cell targeting, and cell uptake under both physiological and pathological conditions. In this review, we bring other insight into the involvement of tetraspanin proteins in extracellular vesicle physiology in mammalian reproduction. We provide knowledge regarding the involvement of extracellular vesicle tetraspanins in these processes in somatic cells. Furthermore, we discuss the future direction towards an understanding of their functions in the tissues and fluids of the mammalian reproductive system in gamete maturation, fertilization, and embryo development; their involvement in mutual cell contact and communication in their complexity.

Roles of male reproductive tract extracellular vesicles in reproduction

Extracellular vesicles (EVs) are secreted cell-derived membrane structures present in all organisms across animal, bacterial, and plant phyla. These vesicles play important roles in cell-cell communication in many processes integral to health and disease. Recent studies demonstrate that EVs and their cargo have influential and conserved roles in male reproduction. While EVs have been isolated from virtually all specialized tissues comprising the male reproductive tract, they are best characterized in the epididymis (epididymosomes) and seminal fluid (seminal fluid extracellular vesicles or prostasomes). Broadly speaking, EVs promote reproductive success through supporting sperm development and function, as well as influencing the physiology of female reproductive tract cells after mating. In this review, we present current knowledge on the composition and function of male reproductive tract EV populations in both normal physiology and pathology, and argue that their functions identify them as critical regulators of fertility and fecundity.

GPx8 Expression in Rat Oocytes, Embryos, and Female Genital Organs During Preimplantation Period of Pregnancy

This study aimed to detect the presence of glutathione peroxidase 8 (GPx8) in rat during preimplantation period of pregnancy. Females were killed on first (D1), third (D3), and fifth (D5) day of pregnancy. The presence of GPx8 in embryos was detected under the confocal microscope, the presence of GPx8 in genital organs was confirmed immunohistochemically, and the amount of GPx8 was determined using densitometry. We found that GPx8 is dispersed in the cytoplasm of oocytes, while after fertilization, it is concentrated in granules. From 4-cell stage till blastocyst, GPx8 reaction was found in the perinuclear region. In the ovary, GPx8 was seen in granulosa-lutein cells, in plasma of blood vessels, and inside Graafian follicles. In oviduct, GPx8 was detected in the plasma and in the extracellular matrix (ECM). Moreover, epithelial cells of isthmus were positive. In uterus, GPx8 was observed in the uterine glands, in the plasma, and in ECM. On D5, the enzyme disappeared from the uterine glands and appeared in fibroblasts. Densitometry revealed that the highest amount of GPx8 was on D1 and subsequently declined. To our knowledge, this is the first paper describing GPx8 presence in the oocytes, preimplantation embryos, and female genital organs in mammals. Our results improve the understanding of antioxidant enzymes presence during pregnancy in defense against oxidative stress, which is considered to be one of the main causes of infertility.

Exosomes of male reproduction

Exosomes are nanosized membrane vesicles secreted by wide variety of cells and found in abundance in biological fluids including semen. They contain cargo of lipids, proteins, microRNAs and mRNAs, and are known to play a major role in intracellular communication. Seminal exosomes mainly include epididymosomes and prostasomes. Most of the proteins associated with the epididymosomes are transferred to the sperm subcellular or membranous domains during their epididymal transit and are involved in the acquisition of fertilizing ability, modulation of motility and protection against oxidative stress. Proteins associated with prostasomes stimulate sperm motility and regulate the timing of capacitation to avoid premature induction of acrosome reaction. Furthermore, prostasomes protect the sperm from immune responses within the female reproductive tract. Overall, exosome-associated proteins play an indispensable role in maturation of spermatozoa and therefore, serve as an excellent biomarker in early diagnosis of male infertility.

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

INTRODUCTION

We verify whether finasteride had a transgenerational effect on the epididymal expression of antioxidant enzymes, and the correlation between these enzymes and blood androgen concentrations in male offspring (F1:Fin) of females fertilized by finasteride-treated male rats.

MATERIAL AND METHODS

The expression of CAT, SOD1, GPX5, GR on the mRNA and protein levels was evaluated in the epididymis at postnatal day (PND) 7, 14, 21, 28 and 90. Levels of T and DHT were correlated with mRNA levels of enzymes by Spearman's rank correlation coefficient.

RESULTS

A change in the levels of transcripts was noted in F1:Fin rats: CAT decreased at PND 28 (p < 0.01) and increased at PND 90 (p < 0.01); SOD1 increased at PND 7 (p < 0.0001), 21 (p < 0.001), 90 (p < 0.0001) and decreased at 14 PND (p < 0.01); GPX5 increased at PND 14 and 21 (p < 0.0001); GR decreased at PND 21 and 28 (p < 0.0001). Altered immunolocalization of enzymes within the epididymal epithelium was observed. Negative correlations between GPX5 mRNA with androgens (T, p = 0.0002; DHT, p = 0.0009) were visible in the control rats, and positive correlation between DHT and CAT mRNA (p = 0.03), in opposite to F1:Fin group were was negative for both androgens (T, p = 0.044 and DHT, p = 0.02).

CONCLUSIONS

Finasteride treatment of adult male rats may cause changes in antioxidant defense system in the epididymis of their offspring, leading to improper ROS concentrations that can affect post-testicular sperm maturation.

MicroRNAs as Potential Regulators of Glutathione Peroxidases Expression and Their Role in Obesity and Related Pathologies

Glutathione peroxidases (GPxs) belong to the eight-member family of phylogenetically related enzymes with different cellular localization, but distinct antioxidant function. Several GPxs are important selenoproteins. Dysregulated GPx expression is connected with severe pathologies, including obesity and diabetes. We performed a comprehensive bioinformatic analysis using the programs miRDB, miRanda, TargetScan, and Diana in the search for hypothetical microRNAs targeting 3′untranslated regions (3´UTR) of GPxs. We cross-referenced the literature for possible intersections between our results and available reports on identified microRNAs, with a special focus on the microRNAs related to oxidative stress, obesity, and related pathologies. We identified many microRNAs with an association with oxidative stress and obesity as putative regulators of GPxs. In particular, miR-185-5p was predicted by a larger number of programs to target six GPxs and thus could play the role as their master regulator. This microRNA was altered by selenium deficiency and can play a role as a feedback control of selenoproteins’ expression. Through the bioinformatics analysis we revealed the potential connection of microRNAs, GPxs, obesity, and other redox imbalance related diseases.

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

OBJECTIVE

Selenium-independent glutathione peroxidase (GPx5) is specifically expressed in the mammalian epididymis and plays an important role in protecting sperm from reactive oxygen species and lipid peroxidation damage. This study investigates GPx5 expression in the epididymis of Small Tail Han sheep.

METHODS

GPx5 expression was studied in three age groups: lamb (2 to 3 months), young (8 to 10 months), and adult (18 to 24 months). The epididymis of each age group divided into caput, corpus and cauda, respectively. Analysis the expression quantity of GPx5 in epididymis and testis by real-time fluorescent quantitative polymerase chain reaction and Western blot. Finally, GPx5 protein locating in the epididymis by immunohistochemical.

RESULTS

The results demonstrate that in the lamb group, the GPx5 mRNA, but not protein, can be detected. GPx5 mRNA and expressed protein were detected in both the young and adult groups. Moreover, both the mRNA and protein levels of GPx5 were significantly higher in the young group than in other two groups. When the different segments of epididymis were investigated, GPx5 mRNA was expressed in each segment of epididymis regardless of age. Additionally, the mRNA level in the caput was significantly higher than that in corpus and cauda within same age group. The GPx5 protein was in the epithelial cells' cytoplasm. However, GPx5 mRNA and protein were not detected in the testis.

CONCLUSION

These results suggest that GPx5 is mainly expressed in the epididymis of Small Tail Han sheep, and that the expression level of GPx5 is associated with age. Additionally, GPx5 was primarily expressed in the epithelial cells of the caput. Taken together, these studies indicate that GPx5 is expressed in the epididymis in all age grades.

The use of reduced glutathione (GSH) as antioxidant for cryopreserved sperm in dogs

ABSTRACT The aim of this study was to evaluate the effect of supplementation with different concentrations of reduced glutathione GSH (0; 5; 7.5; 10mM) in the extender for cryopreservation in dogs with evaluations performed after glycerolization (chilled) and thawing (thawed). For this purpose, we used 8 dogs and two semen collections were performed in a weekly interval, totaling 16 semen samples. The sperm were analyzed by automatic sperm motility (CASA) and flow cytometry analysis of mitochondrial potential (JC1 dye) and membrane/acrosome integrity (FITC-PI dyes). We evaluated subjectively the membrane and acrosome integrity, mitochondrial activity and DNA integrity. Seminal plasma was evaluated for lipid peroxidation (TBARS concentration). Chilled and thawed samples supplemented with 7.5 and 10mM of GSH had lower percentage of sperm with high (DAB - Class I) and medium (DAB - Class II) mitochondrial activity. And 10mM of GSH had higher percentage of low mitochondrial activity (DAB - Class III). Moreover, thawed samples of 10mM of GSH had high DNA fragmentation rates. Probably by a reductive stress effect on mitochondria which lead to an increase in reactive oxygen species, and a mitochondrial malfunction.

Induction of immune-related gene expression by seminal exosomes in the porcine endometrium

Seminal plasma (SP) is considered as a vehicle to carry sperm into female reproductive tract, of which functions have not been completely understood. This study aimed to identify the function of seminal exosomes on porcine endometrium. Exosomes were isolated from the sperm-rich fraction of boar semen and were confirmed by the expression of exosome marker HSP70 and size distribution using nano-sight tracking analysis. Porcine endometrial epithelial cells (EECs) were then treated with seminal exosomes, and RNA extracted were subjected to global expression analysis. Transcripts related to "immune response", "inflammatory response" and their associated signaling pathways were up-regulated in EECs treated with seminal exosome, whereas those associated with "steroid biosynthesis", "metabolic pathways" and "T cell differentiation" were down-regulated. The decrease in PMVK, SC5D, INSIG1, HSD17B7, NSDHL, HMGCR, SQLE and FDFT1, and increase in CCL20, TNFSF15, AMCFII, CXCL2 and CXCL8 were also found in the endometrium from the naturally mated pigs. Moreover, changes in exosome-induced CYP24A1, EBP, CCL20, AMCFII and IL1A expression were not regulated by the exosome removed SP. These observations indicated that exosomes present in SP are involved in the immune-related gene regulation in the uterus, which could pave the passage for sperm and possibly fertilized eggs.

Glutathione peroxidases as oncotargets

Oxidative stress is a disturbance in the equilibrium among free radicals, reactive oxygen species, and endogenous antioxidant defense mechanisms. Oxidative stress is a result of imbalance between the production of reactive oxygen and the biological system's ability to detoxify the reactive intermediates or to repair the resulting damage. Mounting evidence has implicated oxidative stress in various physiological and pathological processes, including DNA damage, proliferation, cell adhesion, and survival of cancer cells. Glutathione peroxidases (GPxs) (EC 1.11.1.9) are an enzyme family with peroxidase activity whose main biological roles are to protect organisms from oxidative damage by reducing lipid hydroperoxides as well as free hydrogen peroxide. Currently, 8 sub-members of GPxs have been identified in humans, all capable of reducing H₂O₂ and soluble fatty acid hydroperoxides. A large number of publications has demonstrated that GPxs have significant roles in different stages of carcinogenesis. In this review, we will update recent progress in the study of the roles of GPxs in cancer. Better mechanistic understanding of GPxs will potentially contribute to the development and advancement of improved cancer treatment models.

Copper-Induced Spermatozoa Head Malformation Is Related to Oxidative Damage to Testes in CD-1 Mice

The molecular mechanism for copper toxicity on spermatozoa quality in mice is not well understood. In a 4-week experiment, we challenged 24, 6-week-old male CD-1 mice with twice-a-week intraperitoneal copper chloride injections and evaluated spermatozoa quality, copper levels in the testes, serum testosterone, the expression of key antioxidant glutathione peroxidase 5 (GPx5), and the regulated androgen receptor (AR) in the mice testes. We compared these outcomes for four groups of six mice given doses of 0, 1.25, 2.5, 5.0 mg/kg weight copper chloride twice a week for 4 weeks. The mice demonstrated a copper increase spermatozoa head malformation in a dose-response manner. However, we observed no changes in spermatozoa viability and acrosome integrity in the ratio of mouse body weight to testes weight or in the histomorphology of the testes as the average copper level increased. Results of our RT-PCR assays, immunohistochemical tests, ELISA, and histochemistry analyses indicated that testis GPx5 expression was increased, AR expression in the testes was decreased, serum testosterone was decreased, and the activity of 3β-hydroxysteroid dehydrogenase was decreased as the copper dose increased. In conclusion, these data show that sublethal exposure to copper induces spermatozoa head malformation and influences both mRNA and protein levels of GPx5 and AR which is related to copper resides in the testes.

Glutathione Peroxidase 5 Is Expressed by the Entire Pig Male Genital Tract and Once in the Seminal Plasma Contributes to Sperm Survival and In Vivo Fertility

Glutathione peroxidase-5 (GPX5) is an H₂O₂-scavenging enzyme identified in boar seminal plasma (SP). This study attempted to clarify its origin and role on sperm survival and fertility after artificial insemination (AI). GPX5 was expressed (Western blot and immunocytochemistry using a rabbit primary polyclonal antibody) in testes, epididymis and accessory sex glands (6 boars). SP-GPX5 concentration differed among boars (11 boars, P < 0.001), among ejaculates within boar (44 ejaculates, P < 0.001) and among portions within ejaculate (15 ejaculates). The first 10 mL of the sperm rich fraction (SRF, sperm-peak portion) had a significantly lower concentration (8.87 ± 0.78 ng/mL) than the rest of the SRF and the post-SRF (11.66 ± 0.79 and 12.37 ± 0.79 ng/mL, respectively, P < 0.005). Sperm motility of liquid-stored semen AI-doses (n = 44, at 15–17°C during 72h) declined faster in AI-doses with low concentrations of SP-GPX5 compared to those with high-levels. Boars (n = 11) with high SP-GPX5 showed higher farrowing rates and litter sizes than those with low SP-GPX5 (a total of 5,275 inseminated sows). In sum, GPX5 is widely expressed in the boar genital tract and its variable presence in SP shows a positive relationship with sperm quality and fertility outcomes of liquid-stored semen AI-doses.

Extracellular vesicles: roles in gamete maturation, fertilization and embryo implantation

BACKGROUND

Extracellular vesicles (EVs) are membrane-bound vesicles, found in biofluids, that carry and transfer regulatory molecules, such as microRNAs (miRNAs) and proteins, and may mediate intercellular communication between cells and tissues. EVs have been isolated from a wide variety of biofluids, including plasma, urine, and, relevant to this review, seminal, follicular and uterine luminal fluid. We conducted a systematic search of the literature to review and present the currently available evidence on the possible roles of EVs in follicular growth, resumption of oocyte development and maturation (meiosis), sperm maturation, fertilization and embryo implantation.

METHODS

MEDLINE, Embase and Web of Science databases were searched using keywords pertaining to EVs, including 'extracellular vesicles', 'microvesicles', 'microparticles' and 'exosomes', combined with a range of terms associated with the period of development between fertilization and implantation, including 'oocyte', 'sperm', 'semen', 'fertilization', 'implantation', 'embryo', 'follicular fluid', 'epididymal fluid' and 'seminal fluid'. Relevant research articles published in English (both animal and human studies) were reviewed with no restrictions on publication date (i.e. from earliest database dates to July 2015). References from these articles were used to obtain additional articles.

RESULTS

A total of 1556 records were retrieved from the three databases. After removing duplicates and irrelevant titles, we reviewed the abstracts of 201 articles, which included 92 relevant articles. Both animal and human studies unequivocally identified various types of EVs in seminal, follicular and ULFs. Several studies provided evidence for the roles of EVs in these biofluids. In men, EVs in seminal fluid were linked with post-testicular sperm maturation, including sperm motility acquisition and reduction of oxidative stress. In women, EVs in follicular fluid were shown to contain miRNAs with potential roles in follicular growth, resumption of oocyte meiosis, steroidogenesis and prevention of polyspermy after fertilization. EVs were also detected in the media of cultured embryos, suggesting that EVs released from embryos and the uterus may mediate embryo-endometrium cross-talk during implantation. It is important to note that many of the biologically plausible functions of EVs in reproduction discussed in the current literature have not yet been substantiated by conclusive experimental evidence.

CONCLUSIONS

A detailed understanding of the contributions of EVs in the series of events from gametogenesis to fertilization and then on to implantation, in both normal and pathological cases, may enable the development of valuable tools to advance reproductive health. Because of the early stage of the field, it is unsurprising that the current literature includes not only growing experimental evidence, but also as-yet unproven hypotheses pertaining to the roles of EVs in key reproductive processes. In this review, we present a comprehensive survey of the rapidly expanding literature on this subject, highlighting both relevant findings and gaps in knowledge.

Sperm Proteome Maturation in the Mouse Epididymis

In mammals, transit through the epididymis, which involves the acquisition, loss and modification of proteins, is required to confer motility and fertilization competency to sperm. The overall dynamics of maturation is poorly understood, and a systems level understanding of the complex maturation process will provide valuable new information about changes occurring during epididymal transport. We report the proteomes of sperm collected from the caput, corpus and cauda segments of the mouse epididymis, identifying 1536, 1720 and 1234 proteins respectively. This study identified 765 proteins that are present in sperm obtained from all three segments. We identified 1766 proteins that are potentially added (732) or removed (1034) from sperm during epididymal transit. Phenotypic analyses of the caput, corpus and cauda sperm proteomes identified 60 proteins that have known sperm phenotypes when mutated, or absent from sperm. Our analysis indicates that as much as one-third of proteins with known sperm phenotypes are added to sperm during epididymal transit. GO analyses revealed that cauda sperm are enriched for specific functions including sperm-egg recognition and motility, consistent with the observation that sperm acquire motility and fertilization competency during transit through the epididymis. In addition, GO analyses revealed that the immunity protein profile of sperm changes during sperm maturation. Finally, we identified components of the 26S proteasome, the immunoproteasome, and a proteasome activator in mature sperm.

Chromatin and extracellular vesicle associated sperm RNAs

A diverse pool of RNAs remain encapsulated within the transcriptionally silent spermatozoon despite the dramatic reduction in cellular and nuclear volume following cytoplasm/nucleoplasm expulsion. The impact of this pronounced restructuring on the distribution of transcripts inside the sperm essentially remains unknown. To define their compartmentalization, total RNA >100 nt was extracted from sonicated (SS) mouse spermatozoa and detergent demembranated sucrose gradient fractionated (Cs/Tx) sperm heads. Sperm RNAs predominately localized toward the periphery. The corresponding distribution of transcripts and thus localization and complexity were then inferred by RNA-seq. Interestingly, the number of annotated RNAs in the CsTx sperm heads exhibiting reduced peripheral enrichment was restricted. However this included Cabyr, the calcium-binding tyrosine phosphorylation-regulated protein encoded transcript. It is present in murine zygotes prior to the maternal to the zygotic transition yet absent in oocytes, consistent with the delivery of internally positioned sperm-borne RNAs to the embryo. In comparison, transcripts enriched in sonicated sperm contributed to the mitochondria and exosomes along with several nuclear transcripts including the metastasis associated lung adenocarcinoma transcript 1 (Malat1) and several small nucleolar RNAs. Their preferential peripheral localization suggests that chromatin remodeling during spermiogenesis is not limited to nucleoproteins as part of the nucleoprotein exchange.

Glutathione peroxidase 8 is transcriptionally regulated by HIFα and modulates growth factor signaling in HeLa cells

GPx8 is a mammalian Cys-glutathione peroxidase of the endoplasmic reticulum membrane, involved in protein folding. Its regulation is mostly unknown. We addressed both the functionality of two hypoxia-response elements (HREs) within the promoter, GPx8 HRE1 and GPx8 HRE2, and the GPx8 physiological role. In HeLa cells, treatment with HIFα stabilizers, such as diethyl succinate (DES) or 2-2'-bipyridyl (BP), induces GPx8 expression at both mRNA and protein level. Luciferase activity of pGL3(GPx8wt), containing a fragment of the GPx8 promoter including the two HREs, is also induced by DES/BP or by overexpressing either individual HIFα subunit. Mutating GPx8 HRE1 within pGL3(GPx8wt) resulted in a significantly higher inhibition of luciferase activity than mutating GPx8 HRE2. Electrophoretic mobility-shift assay showed that both HREs exhibit enhanced binding to a nuclear extract from DES/BP-treated cells, with stronger binding by GPx8 HRE1. In DES-treated cells transfected with pGL3(GPx8wt) or mutants thereof, silencing of HIF2α, but not HIF1α, abolishes luciferase activity. Thus GPx8 is a novel HIF target preferentially responding to HIF2α binding at its two novel functional GPx8 HREs, with GPx8 HRE1 playing the major role. Fibroblast growth factor (FGF) treatment increases GPx8 mRNA expression, and reporter gene experiments indicate that induction occurs via HIF. Comparing the effects of depleting GPx8 on the downstream effectors of FGF or insulin signaling revealed that absence of GPx8 results in a 16- or 12-fold increase in phosphorylated ERK1/2 by FGF or insulin treatment, respectively. Furthermore, in GPx8-depleted cells, phosphorylation of AKT by insulin treatment increases 2.5-fold. We suggest that induction of GPx8 expression by HIF slows down proliferative signaling during hypoxia and/or growth stimulation through receptor tyrosine kinases.

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

Mammalian spermatozoa are unique cells in many ways, and the acquisition of their main function, i.e. fertilization capacity, is a multistep process starting in the male gonad and ending near the female egg for the few cells reaching this point. Owing to the unique character of this cell, the molecular pathways necessary to achieve its maturation also show some specific characteristics. One of the most striking specificities of the spermatozoon is that its DNA is highly compacted after the replacement of histones by protamines, making the classical processes of transcription and translation impossible. The sperm cells are thus totally dependent on their extracellular environment for their protection against oxidative stress, for example, or for the molecular changes occurring during the transit of the epididymis; the first organ in which post-testicular maturation takes place. The molecular mechanisms underlying sperm maturation are still largely unknown, but it has been shown in the past three decades that extracellular vesicles secreted by the male reproductive tract are involved in this process. This review will examine the roles played by two types of naturally occurring extracellular vesicles, epididymosomes and prostasomes, secreted by the epididymis and the prostate respectively. We will also describe how the use of artificial vesicles, liposomes, contributed to the study of male reproductive physiology.

Glutathione peroxidases

BACKGROUND

With increasing evidence that hydroperoxides are not only toxic but rather exert essential physiological functions, also hydroperoxide removing enzymes have to be re-viewed. In mammals, the peroxidases inter alia comprise the 8 glutathione peroxidases (GPx1-GPx8) so far identified.

SCOPE OF THE REVIEW

Since GPxs have recently been reviewed under various aspects, we here focus on novel findings considering their diverse physiological roles exceeding an antioxidant activity.

MAJOR CONCLUSIONS

GPxs are involved in balancing the H2O2 homeostasis in signalling cascades, e.g. in the insulin signalling pathway by GPx1; GPx2 plays a dual role in carcinogenesis depending on the mode of initiation and cancer stage; GPx3 is membrane associated possibly explaining a peroxidatic function despite low plasma concentrations of GSH; GPx4 has novel roles in the regulation of apoptosis and, together with GPx5, in male fertility. Functions of GPx6 are still unknown, and the proposed involvement of GPx7 and GPx8 in protein folding awaits elucidation.

GENERAL SIGNIFICANCE

Collectively, selenium-containing GPxs (GPx1-4 and 6) as well as their non-selenium congeners (GPx5, 7 and 8) became key players in important biological contexts far beyond the detoxification of hydroperoxides. This article is part of a Special Issue entitled Cellular functions of glutathione.

Maturational changes in the survivability and fertility of fowl sperm during their passage through the male reproductive tract

The objective of this study was to examine whether domestic fowl (Gallus domesticus) sperm undergo maturation in their capacity for survival and fertilization in the male reproductive tract. Sperm collected from the testis, epididymis and the proximal, middle and distal vas deferens were simultaneously stored in vitro in minimum essential medium (MEM) at 39°C for 0, 3 and 6h, and at 4°C for 24 and 48h. Sperm membrane integrity was measured using the dual fluorescent stain SYBR-14/propidium iodide (PI). Aliquots of sperm from the various sites were subjected to artificial insemination (AI) into the uteri of hens to assess the duration of sperm survival in the oviduct and to determine the fertility status of the sperm. Testicular sperm exhibited a very low capacity to survive under in vitro liquid storage conditions, irrespective of the storage temperature used, and in the oviduct, and they had a low ability to fertilize the ovum. On the contrary, sperm from the distal vas deferens had a higher survival rate during in vitro storage periods, a longer life span in the oviduct, and high fertility. Survival and fertilizing capacity of the sperm recovered from the testes increased gradually (P<0.05) from the testes to the distal vas deferens. In conclusion, we suggest that fowl sperm may undergo functional maturation through a process of gradual changes in their survival and fertilization capacities during their passage through the successive parts of the male reproductive tract.

Post testicular sperm maturational changes in the bull: important role of the epididymosomes and prostasomes

After spermatogenesis, testicular spermatozoa are not able to fertilize an oocyte, they must undergo sequential maturational processes. Part of these essential processes occurs during the transit of the spermatozoa through the male reproductive tract. Since the sperm become silent in terms of translation and transcription at the testicular level, all the maturational changes that take place on them are dependent on the interaction of spermatozoa with epididymal and accessory gland fluids. During the last decades, reproductive biotechnologies applied to bovine species have advanced significantly. The knowledge of the bull reproductive physiology is really important for the improvement of these techniques and the development of new ones. This paper focuses on the importance of the sperm interaction with the male reproductive fluids to acquire the fertilizing ability, with special attention to the role of the membranous vesicles present in those fluids and the recent mechanisms of protein acquisition during sperm maturation.

ADAM7 is associated with epididymosomes and integrated into sperm plasma membrane

During epididymal transit, mammalian sperm acquire selected proteins secreted by the epididymis. We previously showed that a disintegrin and metalloprotease (ADAM) 7 is expressed specifically in the epididymis and transferred to the sperm surface during epididymal transit. Here, we show that mouse ADAM7 secreted to the epididymal lumen is associated with membranous vesicles known as epididymosomes. Furthermore, we found that ADAM7 can be transferred directly from epididymal vesicles to sperm and that it is an integral plasma membrane protein in sperm. Thus, our study provides new information regarding the unique mode of secretion and interaction of ADAM7 during the epididymis-to-sperm transfer process.

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

The mammalian epididymis provides sperm with an environment that promotes their maturation and protects them from external stresses. For example, it harbors an array of antioxidants, including non-conventional glutathione peroxidase 5 (GPX5), to protect them from oxidative stress. To explore the role of GPX5 in the epididymis, we generated mice that lack epididymal expression of the enzyme. Histological analyses of Gpx5-/- epididymides and sperm cells revealed no obvious defects. Furthermore, there were no apparent differences in the fertilization rate of sexually mature Gpx5-/- male mice compared with WT male mice. However, a higher incidence of miscarriages and developmental defects were observed when WT female mice were mated with Gpx5-deficient males over 1 year old compared with WT males of the same age. Flow cytometric analysis of spermatozoa recovered from Gpx5-null and WT male mice revealed that sperm DNA compaction was substantially lower in the cauda epididymides of Gpx5-null animals and that they suffered from DNA oxidative attacks. Real-time PCR analysis of enzymatic scavengers expressed in the mouse epididymis indicated that the cauda epididymidis epithelium of Gpx5-null male mice mounted an antioxidant response to cope with an excess of ROS. These observations suggest that GPX5 is a potent antioxidant scavenger in the luminal compartment of the mouse cauda epididymidis that protects spermatozoa from oxidative injuries that could compromise their integrity and, consequently, embryo viability.

GPX5, the selenium-independent glutathione peroxidase-encoding single copy gene is differentially expressed in mouse epididymis

Using various molecular approaches, including reverse transcription–polymerase chain reaction (RT–PCR), rapid amplification of cDNA ends–PCR, sequencing, northern and western blotting, we found that the mouse GPX5 gene gives rise to at least three different transcripts that are not expressed at the same levels in the mouse epididymis. In addition to the major GPX5 transcript, we show that minor GPX5 transcripts exist, arising either from precocious termination of transcription or an alternative splicing event within intron 4 of the 5 exon-encoding GPX5 single copy gene. Furthermore, we demonstrate that variants of the GPX5 protein that are correlated with the shorter GPX5 transcripts can be detected in caput epididymidis protein extracts and that the various GPX5 isoforms are subject to differential post-transcriptional maturation processes in the mouse epididymis that essentially involve the addition of O-glycosyl extensions. Using a sensitive poly-A+ mRNA tissue blot, as well as RT–PCR and northern assays, we further show that in addition to being expressed in the epididymis, the GPX5 gene is also expressed, albeit at lower levels, in other tissues of the male genital tract, including the testis and prostate. Finally, we present evidence suggesting that the GPX5 gene is expressed in a temporally regulated manner during mouse embryonic development.

Epididymosomes are involved in the acquisition of new sperm proteins during epididymal transit

During epididymal transit, spermatozoa acquire new proteins. Some of these newly acquired proteins behave as integral membrane proteins, including glycosylphosphatidylinositol (GPI)-anchored proteins. This suggests that the secreted epididymal proteins are transferred to spermatozoa by an unusual mechanism. Within the epididymal lumen, spermatozoa interact with small membranous vesicles named epididymosomes. Many proteins are associated with epididymosomes and the protein composition of these vesicles varies along the excurrent duct and differs from soluble intraluminal proteins. Some epididymosome-associated proteins have been identified and their functions in sperm maturation hypothesized. These include P25b, a zona pellucida binding protein, macrophage migration inhibitory factor, enzymes of the polyol pathway, HE5/CD52, type 5 glutathione peroxidase, and SPAM1 or PH-20. The electrophoretic patterns of proteins associated to epididymosomes are complex and some of these proteins are transferred to defined surface domains of epididymal spermatozoa. Epididymosomes collected from different epididymal segments interact differently with spermatozoa. This protein transfer from epididymosomes to spermatozoa is time-dependent, temperature-dependent and pH-dependent, and is more efficient in the presence of zinc. Some proteins are segregated to lipid raft domains of epididymosomes and are selectively transferred to raft domains of the sperm plasma membrane. Some evidence is presented showing that epididymosomes are secreted in an apocrine manner by the epididymal epithelial cells. In conclusion, epididymosomes are small membranous vesicles secreted in an apocrine manner in the intraluminal compartment of the epididymis and play a major role in the acquisition of new proteins by the maturing spermatozoa.