Insights into the Role of Glutathione Peroxidase 3 in Non-Neoplastic Diseases

Reactive oxygen species (ROSs) are byproducts of normal cellular metabolism and play pivotal roles in various physiological processes. Disruptions in the balance between ROS levels and the body's antioxidant defenses can lead to the development of numerous diseases. Glutathione peroxidase 3 (GPX3), a key component of the body's antioxidant system, is an oxidoreductase enzyme. GPX3 mitigates oxidative damage by catalyzing the conversion of hydrogen peroxide into water. Beyond its antioxidant function, GPX3 is vital in regulating metabolism, modulating cell growth, inducing apoptosis and facilitating signal transduction. It also serves as a significant tumor suppressor in various cancers. Recent studies have revealed aberrant expression of GPX3 in several non-neoplastic diseases, associating it with multiple pathological processes. This review synthesizes the current understanding of GPX3 expression and regulation, highlighting its extensive roles in noncancerous diseases. Additionally, this paper evaluates the potential of GPX3 as a diagnostic biomarker and explores emerging therapeutic strategies targeting this enzyme, offering potential avenues for future clinical treatment of non-neoplastic conditions.

Exploring novel function of Gpx5 antioxidant activity: Assisting epididymal cells secrete functional extracellular vesicles

Glutathione peroxisomal-5 (Gpx5) promotes the elimination of H2O2 or organic hydrogen peroxide, and plays an important role in the physiological process of resistance to oxidative stress (OS). To directly and better understand the protection of Gpx5 against OS in epididymal cells and sperm, we studied its mechanism of antioxidant protection from multiple aspects. To more directly investigate the role of Gpx5 in combating oxidative damage, we started with epididymal tissue morphology and Gpx5 expression profiles in combination with the mouse epididymal epithelial cell line PC1 (proximal caput 1) expressing recombinant Gpx5. The Gpx5 is highly expressed in adult male epididymal caput, and its protein signal can be detected in the sperm of the whole epididymis. Gpx5 has been shown to alleviate OS damage induced by 3-Nitropropionic Acid (3-NPA), including enhancing antioxidant activity, reducing mitochondrial damage, and suppressing cell apoptosis. Gpx5 reduces OS damage in PC1 and maintains the well-functioning extracellular vesicles (EVs) secreted by PC1, and the additional epididymal EVs play a role in the response of sperm to OS damage, including reducing plasma membrane oxidation and death, and increasing sperm motility and sperm-egg binding ability. Our study suggests that GPX5 plays an important role as an antioxidant in the antioxidant processes of epididymal cells and sperm, including plasma membrane oxidation, mitochondrial oxidation, apoptosis, sperm motility, and sperm-egg binding ability.

Development of a Normal Porcine Cell Line Growing in a Heme-Supplemented, Serum-Free Condition for Cultured Meat

A key element for the cost-effective development of cultured meat is a cell line culturable in serum-free conditions to reduce production costs. Heme supplementation in cultured meat mimics the original meat flavor and color. This study introduced a bacterial extract generated from Corynebacterium that was selected for high-heme expression by directed evolution. A normal porcine cell line, PK15, was used to apply the bacterial heme extract as a supplement. Consistent with prior research, we observed the cytotoxicity of PK15 to the heme extract at 10 mM or higher. However, after long-term exposure, PK15 adapted to tolerate up to 40 mM of heme. An RNA-seq analysis of these heme-adapted PK15 cells (PK15H) revealed a set of altered genes, mainly involved in cell proliferation, metabolism, and inflammation. We found that cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1), lactoperoxidase (LPO), and glutathione peroxidase 5 (GPX5) were upregulated in the PK15H heme dose dependently. When we reduced serum serially from 2% to serum free, we derived the PK15H subpopulation that was transiently maintained with 5-10 mM heme extract. Altogether, our study reports a porcine cell culturable in high-heme media that can be maintained in serum-free conditions and proposes a marker gene that plays a critical role in this adaptation process.

Effects of Reactive Oxygen and Nitrogen Species on Male Fertility

Significance: In recent decades, male fertility has been severely reduced worldwide. The causes underlying this decline are multifactorial, and include, among others, genetic alterations, changes in the microbiome, and the impact of environmental pollutants. Such factors can dysregulate the physiological levels of reactive species of oxygen (ROS) and nitrogen (RNS) in the patient, generating oxidative and nitrosative stress that impairs fertility. Recent Advances: Recent studies have delved into other factors involved in the dysregulation of ROS and RNS levels, such as diet, obesity, persistent infections, environmental pollutants, and gut microbiota, thus leading to new strategies to solve male fertility problems, such as consuming prebiotics to regulate gut flora or treating psychological conditions. Critical Issues: The pathways where ROS or RNS may be involved as modulators are still under investigation. Moreover, the extent to which treatments can rescue male infertility as well as whether they may have side effects remains, in most cases, to be elucidated. For example, it is known that prescription of antioxidants to treat nitrosative stress can alter sperm chromatin condensation, which makes DNA more exposed to ROS and RNS, and may thus affect fertilization and early embryo development. Future Directions: The involvement of extracellular vesicles, which might play a crucial role in cell communication during spermatogenesis and epididymal maturation, and the relevance of other factors such as sperm epigenetic signatures should be envisaged in the future.

Several lines of antioxidant defense against oxidative stress: antioxidant enzymes, nanomaterials with multiple enzyme-mimicking activities, and low-molecular-weight antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role, since they can be either deleterious or beneficial to biological systems. An imbalance between ROS production and elimination is termed oxidative stress, a critical factor and common denominator of many chronic diseases such as cancer, cardiovascular diseases, metabolic diseases, neurological disorders (Alzheimer's and Parkinson's diseases), and other disorders. To counteract the harmful effects of ROS, organisms have evolved a complex, three-line antioxidant defense system. The first-line defense mechanism is the most efficient and involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This line of defense plays an irreplaceable role in the dismutation of superoxide radicals (O2•-) and hydrogen peroxide (H2O2). The removal of superoxide radicals by SOD prevents the formation of the much more damaging peroxynitrite ONOO- (O2•-  + NO• → ONOO-) and maintains the physiologically relevant level of nitric oxide (NO•), an important molecule in neurotransmission, inflammation, and vasodilation. The second-line antioxidant defense pathway involves exogenous diet-derived small-molecule antioxidants. The third-line antioxidant defense is ensured by the repair or removal of oxidized proteins and other biomolecules by a variety of enzyme systems. This review briefly discusses the endogenous (mitochondria, NADPH, xanthine oxidase (XO), Fenton reaction) and exogenous (e.g., smoking, radiation, drugs, pollution) sources of ROS (superoxide radical, hydrogen peroxide, hydroxyl radical, peroxyl radical, hypochlorous acid, peroxynitrite). Attention has been given to the first-line antioxidant defense system provided by SOD, CAT, and GPx. The chemical and molecular mechanisms of antioxidant enzymes, enzyme-related diseases (cancer, cardiovascular, lung, metabolic, and neurological diseases), and the role of enzymes (e.g., GPx4) in cellular processes such as ferroptosis are discussed. Potential therapeutic applications of enzyme mimics and recent progress in metal-based (copper, iron, cobalt, molybdenum, cerium) and nonmetal (carbon)-based nanomaterials with enzyme-like activities (nanozymes) are also discussed. Moreover, attention has been given to the mechanisms of action of low-molecular-weight antioxidants (vitamin C (ascorbate), vitamin E (alpha-tocopherol), carotenoids (e.g., β-carotene, lycopene, lutein), flavonoids (e.g., quercetin, anthocyanins, epicatechin), and glutathione (GSH)), the activation of transcription factors such as Nrf2, and the protection against chronic diseases. Given that there is a discrepancy between preclinical and clinical studies, approaches that may result in greater pharmacological and clinical success of low-molecular-weight antioxidant therapies are also subject to discussion.

Decoding the influence of semen collection processes on goat sperm quality from a perspective of seminal plasma proteomics

This study aims to assess the impact of semen collection methods on goat semen quality and seminal plasma (SP) proteomes. Semen was collected by artificial vagina (AV) or electro-ejaculator (EE) and semen parameters were evaluated. Tandem mass tag coupled with liquid chromatography-tandem mass spectrometry was used to screen SP differentially abundant proteins (DAPs) between EE and AV. PRM was used to confirm the reliability of the data. In contrast to EE, a lower volume, higher progressive motility and concentration were observed in AV. No differences were found in total motility, membrane integrity, acrosome integrity, and ROS production between EE and AV. In total, 1692 proteins were identified in SP, including 210 DAPs. Among them, 120 and 90 proteins were down-regulated and up-regulated in AV compared to EE, respectively. The GO annotation showed that DAPs are mainly localized in the membrane, involved in deference responses to bacterium, RNA processing, and related to oxidoreductase activity. KEGG demonstrated tight associations of DAPs with specific amino acids, carbon metabolism, citrate cycle, and propanoate metabolism. In conclusion, this study provides valuable insights into the effects of semen collection on goat semen quality and explores the potential action mechanism based on the modification of SP proteomes. SIGNIFICANCE OF THE STUDY: The quality of fresh semen directly influences the results of artificial insemination and semen cryopreservation in livestock. This study represents the first attempt to evaluate the impact of semen collection methods including electroejaculation and artificial vagina on sperm quality and seminal plasma proteomes in goat. The results of this study demonstrated that semen collection methods directly impacted the quality of goat semen. Then, the proteomic strategy was used to explore the potential action mechanism of semen collection methods on sperm. Some differentially abundant proteins that potentially influence semen quality were identified. Furthermore, this study suggests the possibility of utilizing specific proteins as predictive markers for goat semen quality.

Ancient Loss of Catalytic Selenocysteine Spurred Convergent Adaptation in a Mammalian Oxidoreductase

Selenocysteine, the 21st amino acid specified by the genetic code, is a rare selenium-containing residue found in the catalytic site of selenoprotein oxidoreductases. Selenocysteine is analogous to the common cysteine amino acid, but its selenium atom offers physical-chemical properties not provided by the corresponding sulfur atom in cysteine. Catalytic sites with selenocysteine in selenoproteins of vertebrates are under strong purifying selection, but one enzyme, glutathione peroxidase 6 (GPX6), independently exchanged selenocysteine for cysteine <100 million years ago in several mammalian lineages. We reconstructed and assayed these ancient enzymes before and after selenocysteine was lost and up to today and found them to have lost their classic ability to reduce hydroperoxides using glutathione. This loss of function, however, was accompanied by additional amino acid changes in the catalytic domain, with protein sites concertedly changing under positive selection across distant lineages abandoning selenocysteine in glutathione peroxidase 6. This demonstrates a narrow evolutionary range in maintaining fitness when sulfur in cysteine impairs the catalytic activity of this protein, with pleiotropy and epistasis likely driving the observed convergent evolution. We propose that the mutations shared across distinct lineages may trigger enzymatic properties beyond those in classic glutathione peroxidases, rather than simply recovering catalytic rate. These findings are an unusual example of adaptive convergence across mammalian selenoproteins, with the evolutionary signatures possibly representing the evolution of novel oxidoreductase functions.

Alleviation of carbendazim toxicity effect by Moringa oleifera oil and Linum usitatissimum L. oil on testes of male rats: Physiological, histological and in silico study

Carbendazim (CBZ) is a widely used fungicide that is used to control the unwanted growth of fungi on fruits and vegetables. Sixty male rats were divided into six groups, each having ten. Group one served as control, animals belonging to group two were exposed to CBZ in the measure of 200 mg/kg body weight (BW). In the third and fourth groups, rats were administered 800 mg/kg BW of Moringa oleifera (moringa oil) and Linum usitatissimum L. (flaxseed oil), plus CBZ with the same dose given to group two. Groups five and six were administered with moringa and flaxseed oils respectively for six weeks. A marked decline was seen in oxidative stress markers, reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and a rise in malondialdehyde (MDA) level in group two with severe histological disruptions. Moringa oil and flaxseed oil were used to alleviate these changes. In addition, a biocomputational molecular docking analysis of three proteins found in male rats was performed. In relation to CBZ (CID:10584007) the screened proteins namely testis-expressed protein (TX101_RAT), EPPI_RAT, and glutathione peroxidase 5 (GPX5_RAT) were docked, and their docking score were obtained (-5.9 kcal/mol), (-5.8 kcal/mol) and (-5.6 kcal/mol) respectively. By examining these interactions in 2D and 3D structures, a detailed understanding of the unique and specific binding affinity, hydrogen bonds, hydrophobic interactions, ionic bonds, and water bonds were obtained. Structure-based virtual screening (SBVS) molecular docking analysis showed that protein interaction with CBZ causes reproductive complications in protein expression and functions by hampering their normal function and blocking active sites.

Glutathione Peroxidase gpx1 to gpx8 Genes Expression in Experimental Brain Tumors Reveals Gender-Dependent Patterns

Extensive research efforts in the field of brain tumor studies have led to the reclassification of tumors by the World Health Organization (WHO) and the identification of various molecular subtypes, aimed at enhancing diagnosis and treatment strategies. However, the quest for biomarkers that can provide a deeper understanding of tumor development mechanisms, particularly in the case of gliomas, remains imperative due to their persistently incurable nature. Oxidative stress has been widely recognized as a key mechanism contributing to the formation and progression of malignant tumors, with imbalances in antioxidant defense systems being one of the underlying causes for the excess production of reactive oxygen species (ROS) implicated in tumor initiation. In this study, we investigated the gene expression patterns of the eight known isoforms of glutathione peroxidase (GPx) in brain tissue obtained from male and female control rats, as well as rats with transplacental ethyl nitrosourea (ENU)-induced brain tumors. Employing the delta-delta Ct method for RT-PCR, we observed minimal expression levels of gpx2, gpx5, gpx6, and gpx7 in the brain tissue from the healthy control animals, while gpx3 and gpx8 exhibited moderate expression levels. Notably, gpx1 and gpx4 displayed the highest expression levels. Gender differences were not observed in the expression profiles of these isoforms in the control animals. Conversely, the tumor tissue exhibited elevated relative expression levels in all isoforms, except for gpx4, which remained unchanged, and gpx5, which exhibited alterations solely in female animals. Moreover, except for gpx1, which displayed no gender differences, the relative expression values of gpx2, gpx3, gpx6, gpx7, and gpx8 were significantly higher in the male animals compared to their female counterparts. Hence, the analysis of glutathione peroxidase isoforms may serve as a valuable approach for discerning the behavior of brain tumors in clinical settings.

Spectacular role of epididymis and bio-active cargo of nano-scale exosome in sperm maturation: A review

The epididymis is responsible for post-testicular sperm maturation as it provides a favorable environment for spermatozoa to gain the ability for movement and fertilization. The recent evidence has shown that, the spermatozoa are vulnerable to dynamic variations driven by various cellular exposure mechanisms mediated by epididymosomes. Exosomes provide new insight into a mechanism of intercellular communication because they provide direct evidence for the transfer of several important bio-active cargo elements (proteins, lipid, DNA, mRNA, microRNA, circular RNA, long noncoding RNA) between epididymis and spermatozoa. In broad sense, proteomic analysis of exosomes from epididymis indicates number of proteins that are involved in sperm motility, acrosomal reaction, prevent pre-mature sperm capacitation and male infertility. Pinpointing, how reproductive disorders are associated with bio-active cargo elements of nano-scale exosome in the male reproductive tract. Therefore, the current review presents evidence regarding the distinctive characteristics and functions of nano-scale exosome in the male reproductive tract in both pathological and physiological developments, and argue that these vesicles serve as an important regulator of male reproduction, fertility, and disease susceptibility.

The emerging role of extracellular vesicles in the testis

Extracellular vesicles (EVs) are nano-sized membrane-bounded particles, released by all cells and capable of transporting bioactive cargoes, proteins, lipids, and nucleic acids, to regulate a variety of biological functions. Seminal plasma is enriched in EVs, and extensive evidence has revealed the role of EVs (e.g. prostasomes and epididymosomes) in the male genital tract. Recently, EVs released from testicular cells have been isolated and identified, and some new insights have been generated on their role in maintaining normal spermatogenesis and steroidogenesis in the testis. In the seminiferous tubules, Sertoli cell-derived EVs can promote the differentiation of spermatogonial stem cells (SSCs), and EVs secreted from undifferentiated A spermatogonia can inhibit the proliferation of SSCs. In the testicular interstitium, EVs have been identified in endothelial cells, macrophages, telocytes, and Leydig cells, although their roles are still elusive. Testicular EVs can also pass through the blood-testis barrier and mediate inter-compartment communication between the seminiferous tubules and the interstitium. Immature Sertoli cell-derived EVs can promote survival and suppress the steroidogenesis of Leydig cells. Exosomes isolated from macrophages can protect spermatogonia from radiation-induced injury. In addition to their role in intercellular communication, testicular EVs may also participate in the removal of aberrant proteins and the delivery of antigens for immune tolerance. EVs released from testicular cells can be detected in seminal plasma, which makes them potential biomarkers reflecting testicular function and disease status. The testicular EVs in seminal plasma may also affect the female reproductive tract to facilitate conception and may even affect early embryogenesis through modulating sperm RNA. EVs represent a new type of intercellular messenger in the testis. A detailed understanding of the role of testicular EV may contribute to the discovery of new mechanisms causing male infertility and enable the development of new diagnostic and therapeutic strategies for the treatment of infertile men.

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.

Research progress of glutathione peroxidase family (GPX) in redoxidation

Maintaining the balance of a cell's redox function is key to determining cell fate. In the critical redox system of mammalian cells, glutathione peroxidase (GPX) is the most prominent family of proteins with a multifaceted function that affects almost all cellular processes. A total of eight members of the GPX family are currently found, namely GPX1-GPX8. They have long been used as antioxidant enzymes to play an important role in combating oxidative stress and maintaining redox balance. However, each member of the GPX family has a different mechanism of action and site of action in maintaining redox balance. GPX1-4 and GPX6 use selenocysteine as the active center to catalyze the reduction of H₂O₂ or organic hydroperoxides to water or corresponding alcohols, thereby reducing their toxicity and maintaining redox balance. In addition to reducing H₂O₂ and small molecule hydroperoxides, GPX4 is also capable of reducing complex lipid compounds. It is the only enzyme in the GPX family that directly reduces and destroys lipid hydroperoxides. The active sites of GPX5 and GPX7-GPX8 do not contain selenium cysteine (Secys), but instead, have cysteine residues (Cys) as their active sites. GPX5 is mainly expressed in epididymal tissue and plays a role in protecting sperm from oxidative stress. Both enzymes, GPX7 and GPX8, are located in the endoplasmic reticulum and are necessary enzymes involved in the oxidative folding of endoplasmic reticulum proteins, and GPX8 also plays an important role in the regulation of Ca²⁺ in the endoplasmic reticulum. With an in-depth understanding of the role of the GPX family members in health and disease development, redox balance has become the functional core of GPX family, in order to further clarify the expression and regulatory mechanism of each member in the redox process, we reviewed GPX family members separately.

Investigation of Sperm and Seminal Plasma Candidate MicroRNAs of Bulls with Differing Fertility and In Silico Prediction of miRNA-mRNA Interaction Network of Reproductive Function

Simple Summary

The objective of this study was to identify differentially expressed (DE) sperm and seminal plasma microRNAs (miRNAs) in high- and low-fertile Holstein bulls (four bulls per group), integrate miRNAs to their target genes, and categorize target genes based on predicted biological processes. Out of 84 bovine-specific, prioritized miRNAs analyzed by RT-PCR, 30 were differentially expressed in high-fertile sperm and seminal plasma compared to low-fertile sperm and seminal plasma, respectively (p ≤ 0.05, fold regulation ≥5 magnitudes). Interestingly, expression levels of DE-miRNAs in sperm and seminal plasma followed a similar pattern. Highly scored integrated genes of DE-miRNAs predicted various biological and molecular functions, cellular process, and pathways. Further in silico analysis revealed categorized genes may have a plausible association with pathways regulating sperm structure and function, fertilization, and embryo and placental development. In conclusion, highly DE-miRNAs in bovine sperm and seminal plasma could be used as a tool for predicting reproductive functions. Since the identified miRNA-mRNA interactions were mostly based on predictions from public databases, the causal regulations of miRNA-mRNA and the underlying mechanisms require further functional characterization in future studies.

Abstract

Recent advances in high-throughput in silico techniques portray experimental data as exemplified biological networks and help us understand the role of individual proteins, interactions, and their biological functions. The objective of this study was to identify differentially expressed (DE) sperm and seminal plasma microRNAs (miRNAs) in high- and low-fertile Holstein bulls (four bulls per group), integrate miRNAs to their target genes, and categorize the target genes based on biological process predictions. Out of 84 bovine-specific, prioritized miRNAs analyzed by RT-PCR, 30 were differentially expressed in high-fertile sperm and seminal plasma compared to low-fertile sperm and seminal plasma, respectively (p ≤ 0.05, fold regulation ≥ 5 magnitudes). The expression levels of DE-miRNAs in sperm and seminal plasma followed a similar pattern. Highly scored integrated genes of DE-miRNAs predicted various biological and molecular functions, cellular process, and pathways. Further, analysis of the categorized genes showed association with pathways regulating sperm structure and function, fertilization, and embryo and placental development. In conclusion, highly DE-miRNAs in bovine sperm and seminal plasma could be used as a tool for predicting reproductive functions. Since the identified miRNA-mRNA interactions were mostly based on predictions from public databases, the causal regulations of miRNA-mRNA and the underlying mechanisms require further functional characterization in future studies.

Simvastatin as an emerging pollutant on non-target aquatic invertebrates: effects on antioxidant-related genes in Daphnia magna

Simvastatin (SIM) is one of the most widely used lipid-lowering drugs and consequently has been frequently detected in various waters. However, its potential adverse effects and toxic mechanisms on non-target organisms such as Daphnia magna (D. magna) remain still unclear. In the present study, the expressions of Nrf2 and antioxidant genes including Keap1, HO-1, GCLC, GST, SOD, CAT, GPx5, GPx7, GRx, TRX, TrxR, and Prx1 in D. magna exposed to SIM for 24 h, 48 h, and 96 h were investigated. The changes of SOD, CAT, GST, and GPx enzymatic activities, and the GSH and MDA content under SIM for 48-h exposure were also addressed. Results showed that the expression of Nrf2 was inhibited at 24 h but induced at 96 h, displaying a time- and/or dose-dependent relationship under SIM exposure. In contrast, Keap1 exhibited induction at 24 h. HO-1 showed significant induction under SIM exposure for different time. SOD generally displayed an induction trend under SIM exposure for different periods. GPX5 expression showed significant induction under SIM exposure, particularly at 24 h in 5 µg L^-1 increasing 15 folds of the control. But GPX7 expression generally displayed inhibition except in 5 µg L^-1. Trx and TrxR showed different induction or inhibition, which was depended on the exposure time and concentration. Prx1 displayed significant induction in most SIM groups. In addition, the decreasing GSH and increasing MDA content also indicated oxidative stress of SIM exposure. Overall, SIM exposure affected the expression of Nrf2 and antioxidant-related genes and altered the redox homeostasis of D. magna, even may cause the morphological changes such as shorten spine and abnormal development eye.

Seminal plasma proteins as potential biomarkers for sperm motility and velocities

Seminal plasma proteins have important roles in sperm functionality, and different mechanisms including micro-vesicle transport of proteins are involved in the regulation of sperm biology. Due to the role of seminal plasma, we hypothesized that specific proteins present in seminal plasma may be used as discriminant variables with potential to identify stallions producing different quality ejaculates; 10 fertile stallions, with different motility and velocity values (although within normal ranges) were used in this study. Motilities and velocities were studied using computer assisted sperm analysis (CASA), while protein composition of the seminal plasma was studied using UHPLC-MS/MS. Specific proteins were more abundant in samples with poorer percentages of total motility, average path velocity and circular velocity, and were: Secreted phosphoprotein 1, Fructose-bisphosphate aldolase (p = 1,95E-09; q = 0.0005) and Malate dehydrogenase 1 (p = 1,41E-11; q = 0.002), to the contrary samples with better straight-line velocity values were enriched in Glutathione peroxidase (p=0.00013; q=0.04) and Triosephosphate isomerase (p=0.00015; q=0.04).

Roles of Oxidative Stress in the Male Reproductive System: Potential of Antioxidant Supplementation for Infertility Treatment

The decline of fertility in modern society is a serious worldwide concern, and the reasons behind it are complex and difficult to unveil. The fact that a big percentage of infertility cases remain diagnosed as idiopathic, turn the strategies to treat such conditions very limited. Nevertheless, one must agree that keeping the oxidative balance of the reproductive tissues should be one of the first lines of treatment for infertile patients. As reported, 30-80% of male infertile individuals present high levels of prooxidant species in the seminal fluid. Thus, antioxidant therapies, which consist of dietary supplementation therapy with one or more antioxidant compound, remain the first step in the treatment of male infertility. Nevertheless, the efficacy of such therapies is variable between individuals. The most common prescribed antioxidants are carnitines and vitamins C and E, but recently phytochemical quercetin has emerged as a potential compound for the treatment of oxidative stress in the male reproductive system. Although there are several animals' evidence about the great potential of quercetin for the treatment of infertility, clinical trials on this subject remain scarce.

ROS as Regulators of Cellular Processes in Melanoma

In this review, we examine the multiple roles of ROS in the pathogenesis of melanoma, focusing on signal transduction and regulation of gene expression. In recent years, different studies have analyzed the dual role of ROS in regulating the redox system, with both negative and positive consequences on human health, depending on cell concentration of these agents. High ROS levels can result from an altered balance between oxidant generation and intracellular antioxidant activity and can produce harmful effects. In contrast, low amounts of ROS are considered beneficial, since they trigger signaling pathways involved in physiological activities and programmed cell death, with protective effects against melanoma. Here, we examine these beneficial roles, which could have interesting implications in melanoma treatment.

Contribution of epididymal epithelial cell functions to sperm epigenetic changes and the health of progeny

BACKGROUND

Spermatozoa acquire their motility and fertilizing abilities during their maturation through the epididymis. This process is controlled by epididymal epithelial cells that possess features adapted to sense and respond to their surrounding environment and to communicate with spermatozoa. During the past decade, new intercellular communication processes have been discovered, including the secretion and transport of molecules from the epithelium to spermatozoa via extracellular vesicles (EVs), as well as sensing of the intraluminal milieu by cellular extensions.

OBJECTIVE AND RATIONALE

This review addresses recent findings regarding epididymal epithelial cell features and interactions between spermatozoa and the epididymal epithelium as well as epigenetic modifications undergone by spermatozoa during transit through the epididymal microenvironment.

SEARCH METHODS

A systematic search was conducted in Pubmed with the keyword 'epididymis'. Results were filtered on original research articles published from 2009 to 2021 and written in the English language. One hundred fifteen original articles presenting recent advancements on the epididymis contribution to sperm maturation were selected. Some additional papers cited in the primary reference were also included. A special focus was given to higher mammalian species, particularly rodents, bovines and humans, that are the most studied in this field.

OUTCOMES

This review provides novel insights into the contribution of epididymal epithelium and EVs to post-testicular sperm maturation. First, new immune cell populations have been described in the epididymis, where they are proposed to play a role in protecting the environment surrounding sperm against infections or autoimmune responses. Second, novel epididymal cell extensions, including dendrites, axopodia and primary cilia, have been identified as sensors of the environment surrounding sperm. Third, new functions have been outlined for epididymal EVs, which modify the sperm epigenetic profile and participate in transgenerational epigenetic inheritance of paternal traits.

WIDER IMPLICATIONS

Although the majority of these findings result from studies in rodents, this fundamental research will ultimately improve our knowledge of human reproductive physiopathologies. Recent discoveries linking sperm epigenetic modifications with paternal environmental exposure and progeny outcome further stress the importance of advancing fundamental research on the epididymis. From this, new therapeutic options for infertile couples and better counseling strategies may arise to increase positive health outcomes in children conceived either naturally or with ART.

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.

The Role of Extracellular Vesicles in Sperm Function and Male Fertility

Within the reproductive tract, distinct cell types must have precisely controlled communication for complex processes such as gamete production, fertilisation and implantation. Intercellular communication in many physiological processes involves extracellular vesicles (EVs). In reproductive systems, EVs have been implicated in many aspects, from gamete maturation to embryo development. Sperm develop within the testis and then exit into the epididymis in an immature form, lacking motility and fertilising capabilities. Due to their small size, compact nature of the nucleus and the lack of specific organelles, sperm are unable to perform de novo protein synthesis, and thus rely on extrinsic signals delivered from the external milieu to gain full function. Mounting evidence points to EVs as being a major provider of these signals, not just within the male reproductive tract but also within the female as the sperm make their way through a seemingly hostile environment to the oocyte. In this chapter, we review the current knowledge on EVs as mediators of sperm maturation and function and highlight their potential roles in male fertility.

Impact of diabetic hyperglycaemia and insulin therapy on autophagy and impairment in rat epididymis

Blood glucose dysregulation and hyperglycaemia caused by diabetes mellitus are intimately associated with male infertility. Two-month-old Sprague-Dawley rats were given a single dose of streptozotocin (55 mg/kg) by intraperitoneal injection to induce type I diabetes mellitus (DM group). The treatment group was given 1 unit/day of insulin for 16 weeks (INS group). The normal control group (NC group) was given food ad libitum. In the DM group, the histological analysis of caput and cauda epididymal ducts showed broken stereocilia and more lipid vacuolisations in the principal cells. The interstitial hyperplasia and inflammatory cell infiltration were observed in epididymal tissues. Transmission electron microscopy observation showed that the principal cells in the DM group contained more vacuoles, partly lost stereocilia, and swollen mitochondria. The autophagosomes were observed as well. Western blotting results of LC3II/I and P62 protein expression indicated that autophagy was downregulated in the DM group. The total antioxidant activity and GPx5 expression of epididymal tissues were also decreased. In the INS group, significant improvements were observed in epididymal tissues. Our study suggests that diabetic hyperglycaemia causes autophagy dysregulation in epididymal tissues, which may play a role in diabetes-induced rat epididymal injury. Insulin treatment is beneficial for diabetic-associated epididymal dysfunction.

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.

Regulatory Phenomena in the Glutathione Peroxidase Superfamily

Significance: The selenium-containing Glutathione peroxidases (GPxs)1-4 protect against oxidative challenge, inhibit inflammation and oxidant-induced regulated cell death. Recent Advances: GPx1 and GPx4 dampen phosphorylation cascades predominantly via prevention of inactivation of phosphatases by H₂O₂ or lipid hydroperoxides. GPx2 regulates the balance between regeneration and apoptotic cell shedding in the intestine. It inhibits inflammation-induced carcinogenesis in the gut but promotes growth of established cancers. GPx3 deficiency facilitates platelet aggregation likely via disinhibition of thromboxane biosynthesis. It is also considered a tumor suppressor. GPx4 is expressed in three different forms. The cytosolic form proved to inhibit interleukin-1-driven nuclear factor κB activation and leukotriene biosynthesis. Moreover, it is a key regulator of ferroptosis, because it reduces hydroperoxy groups of complex lipids and silences lipoxygenases. By alternate substrate use, the nuclear form contributes to chromatin compaction. Mitochondrial GPx4 forms the mitochondrial sheath of spermatozoa and, thus, guarantees male fertility. Out of the less characterized GPxs, the cysteine-containing GPx7 and GPx8 are unique in contributing to oxidative protein folding in the endoplasmic reticulum by reacting with protein isomerase as an alternate substrate. A yeast 2-Cysteine glutathione peroxidase equipped with CP and CR was reported to sense H₂O₂ for inducing an adaptive response. Critical Issues: Most of the findings compiled are derived from tissue culture and/or animal studies only. Their impact on human physiology is sometimes questionable. Future Directions: The expression of individual GPxs and GPx-dependent regulatory phenomena are to be further investigated, in particular in respect to human health.

GPx6 is involved in the in vitro induced capacitation and acrosome reaction in porcine sperm

Glutathione peroxidases (GPxs) are regarded as important protectors against oxidative stress. Some members of this protein family were reported to play key roles in protecting sperm against oxidative stress. Whether GPx6 a member of the GPx family also plays a role in protection against oxidative stress is not known to date. The objective of the present study was to evaluate the localization and function of glutathione peroxidase 6 (GPx6) in boar accessory sex glands, seminal plasma, and sperm, as well as the effect of GPx6 on vitality and capacitation in boar sperm. qPCR and Western blot analysis demonstrated the presence of GPx6 in testis, epididymis, bulbourethral glands, prostate, seminal vesicle, sperm and seminal plasma. Incubation of sperm with an GPx6 antibody had no significant effect on the viability of boar sperm prior to capacitation. Surprisingly, when capacitated sperm was incubated with the GPx6 antibody for 240 min, sperm vitality was significantly improved. Western blotting showed that in capacitated sperm without prior pretreatment, GPx6 protein content was reduced compared to sperm before capacitation. To further confirm a role for GPx6 in sperm capacitation, we tested sperm acrosome reaction by ACR.2 and FITC-PSA. The results showed that treatment of sperm with the GPx6 antibody significantly increased sperm capacitation and acrosome reaction. Furthermore, we examined the concentration of cAMP in sperm after capacitation. ELISA demonstrated that the cAMP concentration in the sperm exposed to the GPx6 antibody was significantly higher than that of the control group. In addition, the exposure of sperm to the GPx6 antibody significantly increased the concentration of H₂O₂, while the expression of SOD3 and CAT were decreased. Based on these observations we would like to postulate that in the boar reproductive tract the GPx6 protein becomes attached to the sperm head preventing the sperm to undergo premature capacitation by affecting components of the antioxidant pathway. How GPx6 expression following ejaculation becomes suppressed to allow sperm capacitation to take place needs further investigation.

Comparative proteomics reveals protective effect of resveratrol on a high-fat diet-induced damage to mice testis

In recent years, resveratrol has been shown to protect against metabolic damage, including obesity-associated subfertility/infertility. In the present study, proteomic alterations in testicular tissues were investigated by tandem mass tag (TMT) in mice fed with a high-fat diet (HFD) without or with resveratrol supplementation (HFD+RSV). Serum testosterone levels, spermatozoa parameters and testicular histological morphology were assessed. Resveratrol treatment was shown to significantly reduce serum cholesterol, prevent the HFD-induced reductions in serum testosterone and spermatozoa parameters, and decrease the ultrastructural degeneration of testicular tissues. The comparative proteomics analysis revealed 58 differentially expressed proteins between the HFD and control groups and 38 differentially expressed proteins between the HFD and HFD+RSV groups. Gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the most highly enriched differential proteins were correlated to spermatozoa function and cholesterol metabolism. The real-time RT-PCR and western blotting results confirmed the differential expression of the corresponding proteins related to spermatozoa function that were identified by proteomics. The present study provides new insight into the mechanisms of the beneficial effects of resveratrol, and may present it as a potential therapeutic strategy for obesity-associated male subfertility/infertility.Abbreviations:TMT: Tandem mass tag; HFD: High-fat diet; RSV: Resveratrol; GO: Gene ontology; Protein-proteinKEGG: Kyoto Encyclopedia of Genes and Genomes; RT-PCR: Reverse transcription-polymerase chain reaction; SDS-PAGE: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis; PVDF: Polyvinylidene fluoride; ECL: Enhanced chemiluminescence; RIPA: Radio-immunoprecipitation assay; CTRL: Control; PPI: interaction; RIA: Radioimmunoassay; T: Testosterone; TG: Triglycerides; TC: Total cholesterol; LDL-c: Low-density lipoprotein cholesterol; HDL-c: High-density lipoprotein cholesterol; Crisp1: Cysteine-rich secretory protein 1; SIRT1: Sirtuin 1; GPx5: Glutathione peroxidase 5; Svs4: Seminal vesicle secretory protein 4; Tssk3: Testis-specific serine kinase 3; Pate4: Prostate and testis expressed 4; Sva: Seminal vesicle antigen; Lcn5: Lipocalin 5; Spinkl: Serine protease inhibitor, Kazal type-like.

Testosterone promotes GPX5 expression of goat epididymal epithelial cells cultured in vitro

Androgens are involved in maintaining epididymal structure and function. In the present study, primary culture of goat EECs and effect of testosterone on expression of glutathione peroxidase-5 (GPX5) in goat epididymal epithelial cells (EECs) were investigated. The EECs isolated from 12-mo-old goat caput epididymis were cultured with testosterone in vitro, and expression of glutathione peroxidase-5 (GPX5) and androgen receptors (ARs) was analyzed. Our results showed that testosterone effectively increased EEC proliferation activity, and EECs cultured with testosterone could maintain molecular markers for up to 12 passages. Compared with the control group, 100 nM testosterone significantly increased the mRNA and protein expression of GPX5 (P < 0.05) and ARs (P < 0.01 and P < 0.05, respectively) in EECs, and this effect was blocked by the AR blocker enzalutamide. In conclusion, testosterone can promote the expression of GPX5 in EECs by up-regulating AR expression. We established an effective culture system for goat EECs which can be for further investigation on the regulation of epithelial function.

Orchestrating the antioxidant defenses in the epididymis

BACKGROUND

During the post-testicular maturation that occurs in the epididymis, spermatozoa need to face biochemical and morphological changes that may make them vulnerable to oxidative damage. During spermatogenesis and the epididymal maturation, the spermatozoon acquires antioxidant enzymes needed to face possible increases of reactive oxygen species (ROS) produced by its own aerobic metabolism but also due to ROS produced in high quantities by abnormal spermatozoa.

OBJECTIVES

Provide an up-to-date review of the enzymatic antioxidant system in the epididymis.

MATERIAL AND METHODS

A thorough literature review was performed for papers concerning the players of the antioxidant defenses in the epididymis.

RESULTS

The antioxidant system in the epididymis is composed by superoxide dismutases, catalase, glutathione peroxidases, peroxiredoxins, glutathione-S-transferases, thioredoxins and thioredoxin reductase. They work together to maintain low levels of ROS during the epididymal maturation. Knockout models revealed that the absence of one of the enzyme impact sperm quality affecting a variety of proteins involved in motility, the ability to fertilize oocyte, and promotes oxidative damage to the sperm DNA.

DISCUSSION AND CONCLUSIONS

These findings suggest that each enzyme is playing a specific role, and in most of the cases, no compensatory mechanisms are put in place when one enzyme is absent. This review highlights the different antioxidant enzymes in the epididymis and their role during maturation of the spermatozoon.

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.

Patterns of expression of sperm and seminal plasma microRNAs in boar semen

Although sperm and seminal plasma differ in their origin, biophysical and biochemical properties of seminal plasma influence the sperm function. Seminal plasma is a fluid medium containing substances from testes, epididymides and accessory glands. Composition of seminal plasma varies among animal species and in boars, prostate and bulbourethral glands are major contributors to the volume and contents. While the origin of some components of seminal plasma are known, the source of recently discovered seminal plasma microRNAs remains unknown, in part due to the difficulty of recovering and characterizing RNA from porcine sperm and seminal plasma. To test the hypothesis that seminal plasma miRNAs interact with sperm, the first objective was to validate protocols for recovering RNAs from porcine seminal plasma and sperm, whereas the second objective was to characterize expression patterns of 84 prioritized microRNAs employing real time PCR methodology. The study identified a relationship between sperm and seminal plasma microRNAs, based on the normalized threshold cycle of amplifying cDNA in sperm and seminal plasma from the same semen of Landrace boars. Therefore, it was concluded that seminal plasma miRNAs may originate from sperm or these miRNAs may shuttle between sperm and seminal plasma in order to facilitate cell-to-cell communication.

Reactive oxygen species and protein modifications in spermatozoa

Cellular response to reactive oxygen species (ROS) includes both reversible redox signaling and irreversible nonenzymatic reactions which depend on the nature and concentration of the ROS involved. Changes in thiol/disulfide pairs affect protein conformation, enzymatic activity, ligand binding, and protein-protein interactions. During spermatogenesis and epididymal maturation, there are ROS-dependent modifications of the sperm chromatin and flagellar proteins.The spermatozoon is regulated by redox mechanisms to acquire fertilizing ability. For this purpose, controlled amounts of ROS are necessary to assure sperm activation (motility and capacitation). Modifications of the thiol groups redox status of sperm proteins are needed for spermatozoon to achieve fertilizing ability. However, when ROS are produced at high concentrations, the established oxidative stress promotes pathological changes affecting sperm function and leading to infertility. Sperm proteins are sensitive to high levels of ROS and suffer modifications that impact on motility, capacitation, and the ability of the spermatozoon to recognize and bind to the zona pellucida and damage of sperm DNA. Thiol oxidation, tyrosine nitration, and S-glutathionylation are highlighted in this review as significant redox-dependent protein modifications associated with impairment of sperm function and alteration of paternal genome leading to infertility. Peroxiredoxins, the primary antioxidant protection in spermatozoa, are affected by most of the protein modifications described in this review. They play a significant role in both physiological and pathological processes in mammalian spermatozoa.

Extracellular Vesicles in Human Reproduction in Health and Disease

Extensive evidence suggests that the release of membrane-enclosed compartments, more commonly known as extracellular vesicles (EVs), is a potent newly identified mechanism of cell-to-cell communication both in normal physiology and in pathological conditions. This review presents evidence about the formation and release of different EVs, their definitive markers and cargo content in reproductive physiological processes, and their capacity to convey information between cells through the transfer of functional protein and genetic information to alter phenotype and function of recipient cells associated with reproductive biology. In the male reproductive tract, epididymosomes and prostasomes participate in regulating sperm motility activation, capacitation, and acrosome reaction. In the female reproductive tract, follicular fluid, oviduct/tube, and uterine cavity EVs are considered as vehicles to carry information during oocyte maturation, fertilization, and embryo-maternal crosstalk. EVs via their cargo might be also involved in the triggering, maintenance, and progression of reproductive- and obstetric-related pathologies such as endometriosis, polycystic ovarian syndrome, preeclampsia, gestational diabetes, and erectile dysfunction. In this review, we provide current knowledge on the present and future use of EVs not only as biomarkers, but also as therapeutic targeting agents, mainly as vectors for drug or compound delivery into target cells and tissues.

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 dynamic metabolomic changes throughout mouse epididymal lumen fluid potentially contribute to sperm maturation

Epididymal lumen fluids are directly responsible for sperm maturation. However, very little is known about the molecular details of small molecule metabolites in the epididymal lumen fluids until now. Here we identified and compared the metabolic profiles of mouse caput and cauda epididymal lumen fluids using GC-MS technique. Among 236 metabolites identified in caput and cauda epididymis, 36 were significantly enriched in caput epididymis while 18 were significantly enriched in cauda epididymis. Pathway analysis identified ascorbate and aldarate metabolism and beta-alanine metabolism as most relevant pathways in caput and cauda epididymis, respectively. Ascorbate, dehydroascorbic acid and beta-alanine associated with these two pathways were firstly reported in mouse epididymal lumen fluids and might play important roles in sperm maturation.

A network-based method using a random walk with restart algorithm and screening tests to identify novel genes associated with Menière's disease

As a chronic illness derived from hair cells of the inner ear, Menière’s disease (MD) negatively influences the quality of life of individuals and leads to a number of symptoms, such as dizziness, temporary hearing loss, and tinnitus. The complete identification of novel genes related to MD would help elucidate its underlying pathological mechanisms and improve its diagnosis and treatment. In this study, a network-based method was developed to identify novel MD-related genes based on known MD-related genes. A human protein-protein interaction (PPI) network was constructed using the PPI information reported in the STRING database. A classic ranking algorithm, the random walk with restart (RWR) algorithm, was employed to search for novel genes using known genes as seed nodes. To make the identified genes more reliable, a series of screening tests, including a permutation test, an interaction test and an enrichment test, were designed to select essential genes from those obtained by the RWR algorithm. As a result, several inferred genes, such as CD4, NOTCH2 and IL6, were discovered. Finally, a detailed biological analysis was performed on fifteen of the important inferred genes, which indicated their strong associations with MD.

In vivo oxidative stress alters thiol redox status of peroxiredoxin 1 and 6 and impairs rat sperm quality

Oxidative stress, the imbalance between the production of reactive oxygen species (ROS) and antioxidant activity is a major culprit of male infertility. Peroxiredoxins (PRDXs) are major antioxidant enzymes of mammalian spermatozoa and are thiol oxidized and inactivated by ROS in a dose-dependent manner. Their deficiency and/or inactivation have been associated with men infertility. The aim of this study was to elucidate the impact of oxidative stress, generated by the in vivo tert-butyl hydroperoxide (tert-BHP) treatment on rat epididymal spermatozoa during their maturation process. Adult Sprague-Dawley males were treated with μmoles tert-BHP/kg or saline (control) per day intraperitoneal for 15 days. Lipid peroxidation (2-thibarbituric acid reactive substances assay), total amount and thiol oxidation of PRDXs along with the total amount of superoxide dismutase (SOD), motility and DNA oxidation (8-hydroxy-deoxyguanosine) were determined in epididymal spermatozoa. Total amount of PRDXs and catalase and thiol oxidation of PRDXs were determined in caput and cauda epididymis. While animals were not affected by treatment, their epididymal spermatozoa have decreased motility, increased levels of DNA oxidation and lipid peroxidation along with increased PRDXs (and not SOD) amounts. Moreover, sperm PRDXs were highly thiol oxidized. There was a differential regulation in the expression of PRDX1 and PRDX6 in the epididymis that suggests a segment-specific role for PRDXs. In conclusion, PRDXs are increased in epididymal spermatozoa in an attempt to fight against the oxidative stress generated by tert-BHP in the epididymis. These findings highlight the role of PRDXs in the protection of sperm function and DNA integrity during epididymal maturation.

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.

Protective role of selenium in the activities of antioxidant enzymes in piglet splenic lymphocytes exposed to deoxynivalenol

We evaluated the effects of selenium (Se) on antioxidant enzymes of piglet splenic lymphocytes exposed to deoxynivalenol (DON). We measured cell viability, the activities of several antioxidant enzymes, and lactate dehydrogenase (LDH), as well as total antioxidant capacity (T-AOC) and the levels of malonaldehyde (MDA) and hydrogen peroxide (H₂O₂). We found that DON exposure increased the concentrations of LDH, MDA, and H₂O₂ in all experimental groups in a dose-dependent manner, while the concentrations of other antioxidant enzymes were decreased. In Se-pretreated DON-exposed cells, damage to antioxidant enzymes was reduced, especially in the lower-dose DON groups over longer exposure times. These results may indicate that in piglet splenic lymphocytes, Se can alleviate DON-induced damage to antioxidant enzymes by improving glutathione peroxidase activity. Se may function as a potential antioxidative agent to alleviate DON-induced oxidative stress.

Role of Zinc Supplementation in Testicular and Epididymal Damages in Diabetic Rat: Involvement of Nrf2, SOD1, and GPX5

Zinc (Zn) is one of the most important trace elements required for several biological processes. Diabetes negatively affects many organs, and diabetic patients are often hypozincemic. The present study aims to investigate the role of Zn supplementation in the testes, epididymis, and sperms of streptozotocin (STZ)-induced diabetic rat. Serum, testicular, and sperm Zn contents were found to be altered in diabetic rat. Biochemical, histopathological, and protein expression profiles were determined to decipher the role of Zn in protecting the cellular perturbations. Further, histopathological analyses of testes and epididymis showed deranged architecture along with other noted abnormalities. Diabetic testes showed decreased Nrf2, HO-1, SOD1, PCNA, and Bcl-2 expressions whereas increased COX-2, NF-κB, MT, IL-6, and p-ERK levels. SOD1 and GPX5 were decreased in the epididymis of diabetic rat, whereas Zn supplementation attenuated these changes. The present results demonstrate the beneficial role of Zn supplementation in diabetes-associated testicular alterations of rat.

Identification of New Epididymal Luminal Fluid Proteins Involved in Sperm Maturation in Infertile Rats Treated by Dutasteride Using iTRAQ

Background: Spermatozoa become mature and acquire fertilizing capacity during their passage through the epididymal lumen. In this study, we identified new epididymal luminal fluid proteins involved in sperm maturation in infertile rats by dutasteride, a dual 5α-reductase inhibitor, in order to provide potential epididymal targets for new contraceptives and infertility treatment. Methods: Male rats were treated with dutasteride for 28 consecutive days. We observed the protein expression profiles in the epididymal luminal fluids in infertile and normal rats using isobaric tags for relative and absolute quantitation (iTRAQ) technique. The confidence of proteome data was validated by enzyme-linked immunosorbent assays. Results: 1045 proteins were tested, and 23 of them presented different expression profiling in the infertile and normal rats. The seven proteins were down-regulated, and 16 proteins were up-regulated. Among the seven proteins which were significantly down-regulated by dutasteride in the epididymal luminal fluids, there were three β-defensins (Defb2, Defb18 and Defb39), which maybe the key proteins involved in epididymal sperm maturation and male fertility. Conclusions: We report for the first time that dutasteride influences the protein expression profiling in the epididymal luminal fluids of rats, and this result provides some new epididymal targets for male contraception and infertility therapy.

Comparative analysis of boar seminal plasma proteome from different freezability ejaculates and identification of Fibronectin 1 as sperm freezability marker

Variation in boar sperm freezability (i.e. capacity to withstand cryopreservation) between ejaculates is a limitation largely reported in the literature. Prediction of sperm freezability and classification of boar ejaculates into good (GFEs) and poor freezability ejaculates (PFEs) before cryopreservation takes place may increase the use of frozen-thawed spermatozoa. While markers of boar sperm freezability have been found from sperm cell extracts, little attention has been paid to seminal plasma. On this basis, the present study compared the fresh seminal plasma proteome of 9 GFEs and 9 PFEs through two-dimensional difference gel electrophoresis (2D-DIGE) and liquid chromatography mass spectrometry (LC-MS/MS). The ejaculates were previously classified as GFE or PFE upon their sperm viability and progressive motility assessments at 30 and 240 min post thawing. From a total of 51 spots, four were found to significantly (p < 0.05) differ between GFEs and PFEs, and two were identified as fibronectin-1 (FN1) and glutathione peroxidase 5 (GPX5). These two potential markers were further studied by western blot and correlation analysis between protein relative abundances in fresh seminal plasma and regression factors from principal component analyses (PCA) run using post-thawing sperm quality parameters. Results confirmed that FN1 is a reliable marker of boar sperm freezability, because GFEs presented significantly (p < 0.05) higher FN1-amounts than PFEs and FN1 was found to be correlated with the first PCA component at 240 min post thawing. In contrast, GPX5 was not validated as a boar sperm freezability marker. We can thus conclude that levels of FN1 in fresh seminal plasma from boar semen may be used as a sperm freezability marker, thereby facilitating the use of frozen-thawed boar spermatozoa.

New insights into epididymal function in relation to sperm maturation

Testicular spermatozoa acquire fertility only after 1 or 2 weeks of transit through the epididymis. At the end of this several meters long epididymal tubule, the male gamete is able to move, capacitate, migrate through the female tract, bind to the egg membrane and fuse to the oocyte to result in a viable embryo. All these sperm properties are acquired after sequential modifications occurring either at the level of the spermatozoon or in the epididymal surroundings. Over the last few decades, significant increases in the understanding of the composition of the male gamete and its surroundings have resulted from the use of new techniques such as genome sequencing, proteomics combined with high-sensitivity mass spectrometry, and gene-knockout approaches. This review reports and discusses the most relevant new results obtained in different species regarding the various cellular processes occurring at the sperm level, in particular, those related to the development of motility and egg binding during epididymal transit.