Sterols in spermatogenesis and sperm maturation

Seminal plasma proteomics as putative biomarkers for male infertility diagnosis

Male infertility represents a significant global public health issue that is currently emerging as a prominent research focus. Presently, laboratories adhere to the guidelines outlined by the World Health Organization (WHO) manuals for conducting routine semen analysis to diagnose male infertility. However, the accuracy of results in predicting sperm quality and fertility is limited because some individuals with a normal semen analysis report, an unremarkable medical history, and a physical examination may still experience infertility. As a result, the importance of employing more advanced techniques to investigate sperm function and male fertility in the treatment of male infertility and/or subfertility becomes apparent. The standard test for evaluating human semen has been improved by more complex tests that look at things like reactive oxygen species (ROS) levels, total antioxidant capacity (TAC), sperm DNA fragmentation levels, DNA compaction, apoptosis, genetic testing, and the presence and location of anti-sperm antibodies. Recent discoveries of novel biomarkers have significantly enriched our understanding of male fertility. Moreover, the notable biological diversity among samples obtained from the same individual complicates the efficacy of routine semen analysis. Therefore, unraveling the molecular mechanisms involved in fertilization is pivotal in expanding our understanding of factors contributing to male infertility. By understanding how these proteins work and what role they play in sperm activity, we can look at the expression profile in men who can't have children to find diagnostic biomarkers. This review examines the various sperm and seminal plasma proteins associated with infertility, as well as proteins that are either deficient or exhibit aberrant expression, potentially contributing to male infertility causes.

The proteomic landscape of sperm surface deciphers its maturational and functional aspects in buffalo

Buffalo is a dominant dairy animal in many agriculture-based economies. However, the poor reproductive efficiency (low conception rate) of the buffalo bulls constrains the realization of its full production potential. This in turn leads to economic and welfare issues, especially for the marginal farmers in such economies. The mammalian sperm surface proteins have been implicated in the regulation of survival and function of the spermatozoa in the female reproductive tract (FRT). Nonetheless, the lack of specific studies on buffalo sperm surface makes it difficult for researchers to explore and investigate the role of these proteins in the regulation of mechanisms associated with sperm protection, survival, and function. This study aimed to generate a buffalo sperm surface-specific proteomic fingerprint (LC-MS/MS) and to predict the functional roles of the identified proteins. The three treatments used to remove sperm surface protein viz. Elevated salt, phosphoinositide phospholipase C (PI-PLC) and in vitro capacitation led to the identification of N = 1,695 proteins (≥1 high-quality peptide-spectrum matches (PSMs), p < 0.05, and FDR<0.01). Almost half of these proteins (N = 873) were found to be involved in crucial processes relevant in the context of male fertility, e.g., spermatogenesis, sperm maturation and protection in the FRT, and gamete interaction or fertilization, amongst others. The extensive sperm-surface proteomic repertoire discovered in this study is unparalleled vis-à-vis the depth of identification of reproduction-specific cell-surface proteins and can provide a potential framework for further studies on the functional aspects of buffalo spermatozoa.

An important role for triglyceride in regulating spermatogenesis

Drosophila is a powerful model to study how lipids affect spermatogenesis. Yet, the contribution of neutral lipids, a major lipid group which resides in organelles called lipid droplets (LD), to sperm development is largely unknown. Emerging evidence suggests LD are present in the testis and that loss of neutral lipid- and LD-associated genes causes subfertility; however, key regulators of testis neutral lipids and LD remain unclear. Here, we show LD are present in early-stage somatic and germline cells within the Drosophila testis. We identified a role for triglyceride lipase brummer (bmm) in regulating testis LD, and found that whole-body loss of bmm leads to defects in sperm development. Importantly, these represent cell-autonomous roles for bmm in regulating testis LD and spermatogenesis. Because lipidomic analysis of bmm mutants revealed excess triglyceride accumulation, and spermatogenic defects in bmm mutants were rescued by genetically blocking triglyceride synthesis, our data suggest that bmm-mediated regulation of triglyceride influences sperm development. This identifies triglyceride as an important neutral lipid that contributes to Drosophila sperm development, and reveals a key role for bmm in regulating testis triglyceride levels during spermatogenesis.

A ripple effect? The impact of obesity on sperm quality and function

Infertility affects approximately 15% of couples trying to conceive. Male-related causes account for roughly 50% of cases, with obesity emerging as a possible significant factor. Obesity, defined as a body mass index of 30.0 or higher, has become a widespread epidemic associated with numerous health issues, including a decrease of fertility. This review discusses the relationship between obesity and male infertility, particularly focusing on sperm quality and function. An overview of the literature suggests that obesity may influence the male reproductive system via disruptions in hormonal profiles, oxidative stress, and inflammation, leading to changes in sperm parameters. Several studies have discussed if obesity causes a decrease in sperm concentration, motility, and normal morphology, so far without a consensus being reached. However, available evidence suggests an impairment of sperm function in obese men, due to an increase in DNA damage and oxidative stress, impaired mitochondrial function and acrosome reaction in response to progesterone. Finally, the relationship between obesity and assisted reproductive technologies outcomes remains debatable, with conflicting evidence regarding the influence on fertilisation, pregnancy, and live birth rates. Therefore, the actual impact of obesity on human spermatozoa still needs to be clarified, due to the multiple factors potentially in play.

Methyl β-Cyclodextrin-sperm-mediated gene editing (MBCD-SMGE): a simple and efficient method for targeted mutant mouse production

BACKGROUND

Generating targeted mutant mice is a crucial technology in biomedical research. This study focuses on optimizing the CRISPR/Cas9 system uptake into sperm cells using the methyl β-cyclodextrin-sperm-mediated gene transfer (MBCD-SMGT) technique to generate targeted mutant blastocysts and mice efficiently. Additionally, the present study elucidates the roles of cholesterol and reactive oxygen species (ROS) in the exogenous DNA uptake by sperm.

RESULTS

In this study, B6D2F1 mouse sperm were incubated in the c-TYH medium with different concentrations of MBCD (0, 0.75, 1, and 2 mM) in the presence of 20 ng/µl pCAG-eCas9-GFP-U6-gRNA (pgRNA-Cas9) for 30 min. Functional parameters, extracellular ROS, and the copy numbers of internalized plasmid per sperm cell were evaluated. Subsequently, in vitro fertilization (IVF) was performed and fertilization rate, early embryonic development, and transfection rate were assessed. Finally, our study investigated the potential of the MBCD-SMGT technique in combination with the CRISPR-Cas9 system, referred to as MBCD-SMGE (MBCD-sperm-mediated gene editing), for generating targeted mutant blastocysts and mice. Results indicated that cholesterol removal from the sperm membrane using MBCD resulted in a premature acrosomal reaction, an increase in extracellular ROS levels, and a dose-dependent influence on the copy numbers of the internalized plasmids per sperm cell. Moreover, the MBCD-SMGT technique led to a larger population of transfected motile sperm and a higher production rate of GFP-positive blastocysts. Additionally, the current study validated the targeted indel in blastocyst and mouse derived from MBCD-SMGE technique.

CONCLUSION

Overall, this study highlights the significant potential of the MBCD-SMGE technique for generating targeted mutant mice. It holds enormous promise for modeling human diseases and improving desirable traits in animals.

Adverse outcome pathways of PBDEs inducing male reproductive toxicity

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants, they are easily released into environment and causing adverse effects to the ecosystem and human health. This review aims to summarize the research status of PBDEs-induced male reproductive toxicity and its mechanisms at various levels such as molecular/cellular, tissue/organ and individual/population. The Adverse Outcome Pathways (AOPs) diagram showed that PBDEs-induced reactive oxygen species (ROS) production, disruptions of estrogen receptor-α (ERα) and antagonism of androgen receptor (AR) were defined as critical molecular initiating events (MIEs). They caused key events (KEs) at the molecular and cellular levels, including oxidative stress, increased DNA damage, damaging mitochondria, increased glycolipid levels and apoptosis, depletion of ectoplasmic specialization and decreased Leydig cells numbers. These in turn lead to followed KEs at the tissue or organ levels, such as the impaired spermatogenesis, impaired blood-testis barrier and reduced testosterone synthesis and function. As a result, reproductive system-related adverse outcomes (AOs) were reported, such as the decreased sperm quantity or quality, shorten male anogenital distance and cryptorchidism in individual and reduced reproduction of the population. This review assembled information on the mechanisms of male reproductive toxicity induced by PBDEs, and constructed a causal mechanism relationship diagram from different levels using the an AOP framework to provide theoretical basis for ecological risk assessment and environmental management of PBDEs. The AOP framework makes it possible to develop risk management strategies based on toxicity mechanisms and support for development of Integrated Approach to Testing and Assessment (IATA) which are available for regulatory purposes.

A comprehensive review on the decabromodiphenyl ether (BDE-209)-induced male reproductive toxicity: Evidences from rodent studies

Polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants (BFRs), are employed in various manufactured products to prevent fires, slow down their spread and reduce the resulting damages. Decabromodiphenyl ether (BDE-209), an example of PBDEs, accounts for approximately 82 % of the total production of PBDEs. BDE-209 is a thyroid hormone (TH)-disrupting chemical owing to its structural similarity with TH. Currently, increase in the level of BDE-209 in biological samples has become a major issue because of its widespread use. BDE-209 causes male reproductive toxicity mainly via impairment of steroidogenesis, generation of oxidative stress (OS) and interference with germ cell dynamics. Further, exposure to this chemical can affect metabolic status, sperm concentration, epigenetic regulation of various developmental genes and integrity of blood-testis barrier in murine testis. However, the possible adverse effects of BDE-209 and its mechanism of action on the male reproductive health have not yet been critically evaluated. Hence, the present review article, with the help of available literature, aims to elucidate the reproductive toxicity of BDE-209 in relation to thyroid dysfunction in rodents. Further, several crucial pathways have been also highlighted in order to strengthen our knowledge on BDE-209-induced male reproductive toxicity. Data were extracted from scientific articles available in PubMed, Web of Science, and other databases. A thorough understanding of the risk assessment of BDE-209 exposure and mechanisms of its action is crucial for greater awareness of the potential threat of this BFR to preserve male fertility.

Rapid azoospermia classification by stimulated Raman scattering and second harmonic generation microscopy

Disease diagnosis and classification pose significant challenges due to the limited capabilities of traditional methods to obtain molecular information with spatial distribution. Optical imaging techniques, utilizing (auto)fluorescence and nonlinear optical signals, introduce new dimensions for biomarkers exploration that can improve diagnosis and classification. Nevertheless, these signals often cover only a limited number of species, impeding a comprehensive assessment of the tissue microenvironment, which is crucial for effective disease diagnosis and therapy. To address this challenge, we developed a multimodal platform, termed stimulated Raman scattering and second harmonic generation microscopy (SRASH), capable of simultaneously providing both chemical bonds and structural information of tissues. Applying SRASH imaging to azoospermia patient samples, we successfully identified lipids, protein, and collagen contrasts, unveiling molecular and structural signatures for non-obstructive azoospermia. This achievement is facilitated by LiteBlendNet-Dx (LBNet-Dx), our diagnostic algorithm, which achieved an outstanding 100% sample-level accuracy in classifying azoospermia, surpassing conventional imaging modalities. As a label-free technique, SRASH imaging eliminates the requirement for sample pre-treatment, demonstrating great potential for clinical translation and enabling molecular imaging-based diagnosis and therapy.

In vitro exposure to triazoles used as fungicides impairs human granulosa cells steroidogenesis

Triazoles are the main components of fungicides used in conventional agriculture. Some data suggests that they may be endocrine disruptors. Here, we found five triazoles, prothioconazole, metconazole, difenoconazole, tetraconazole, and cyproconazole, in soil or water from the Centre-Val de Loire region of France. We then studied their effects from 0.001 µM to 1000 µM for 48 h on the steroidogenesis and cytotoxicity of ovarian cells from patients in this region and the human granulosa line KGN. In addition, the expression of the aryl hydrocarbon receptor (AHR) nuclear receptor in KGN cells was studied. Overall, all triazoles reduced the secretion of progesterone, estradiol, or both at doses that were non-cytotoxic but higher than those found in the environment. This was mainly associated, depending on the triazole, with a decrease in the expression of CYP51, STAR, CYP11A1, CYP19A1, or HSD3B proteins, or a combination thereof, in hGCs and KGN cells and an increase in AHR in KGN cells.

Membrane Cholesterol Inhibits Progesterone-Mediated Sperm Function through the Possible Involvement of ABHD2

Abhydrolase domain containing 2-acylglycerol lipase (ABHD2) was recently claimed as the membrane receptor of progesterone (P4) in sperm cells, mediating cell processes such as sperm chemotaxis and acrosome reaction. Here, we investigated the role of membrane cholesterol (Chol) on ABHD2-mediated human sperm chemotaxis. Human sperm cells were obtained from twelve normozoospemic healthy donors. ABHD2-Chol interaction was modelled by computational molecular-modelling (MM). Sperm membrane Chol content was depleted by incubating cells with cyclodextrin (CD) or augmented by the incubation with the complex between CD and Chol (CD:Chol). Cell Chol levels were quantified by liquid chromatography-mass spectrometry. Sperm migration upon P4 gradient was evaluated through the accumulation assay in a specific migration device. Motility parameters were evaluated by sperm class analyzer, whilst intracellular calcium concentration, acrosome reaction and mitochondrial membrane potential were evaluated with calcium orange, FITC-conjugated anti-CD46 antibody and JC-1 fluorescent probes, respectively. MM analysis showed the possible stable binding Chol to ABHD2, resulting in to major impact on the protein backbone flexibility. The treatment with CD was associated with a dose-dependent increase in sperm migration in a 160 nM P4 gradient, together with increase in sperm motility parameters and levels of acrosome reaction. The treatment with CD:Chol was associated with essentially opposite effects. Chol was, thus, suggested to inhibit P4-mediated sperm function through the possible inhibition of ABHD2.

Comparative Analysis of Epididymis Cauda of Yak before and after Sexual Maturity

Epididymis development is the basis of male reproduction and is a crucial site where sperm maturation occurs. In order to further understand the epididymal development of yak and how to regulate sperm maturation, we conducted a multi-omics analysis. We detected 2274 differential genes, 222 differential proteins and 117 co-expression genes in the cauda epididymis of yak before and after sexual maturity by RNA-seq and proteomics techniques, which included TGFBI, COL1A1, COL1A2, COL3A1, COL12A1, SULT2B1, KRT19, and NPC2. These high abundance genes are mainly related to cell growth, differentiation, adhesion and sperm maturation, and are mainly enriched via extracellular matrix receptor interaction, protein differentiation and absorption, and lysosome and estrogen signaling pathways. The abnormal expression of these genes may lead to the retardation of epididymal cauda development and abnormal sperm function in yak. In conclusion, through single and combined analysis, we provided a theoretical basis for the development of the yak epididymal cauda, sperm maturation, and screening of key genes involved in the regulation of male yak reproduction.

The Association Between Lipid Serum and Semen Parameters: a Systematic Review

Increased lipid levels sometimes not only affect sexual function but also are considered to harm semen quality. It is often a suspicion that elevated lipids are a factor in infertility. We conduct a systematic review. Articles that met the criteria were identified according to The Preferred Reporting Items for Systematic Review and Meta-analysis of recommendations in the PubMed, ProQuest, EBSCO, Web of Science Wiley Online, Springer Link, Scopus, and Science Direct databases with no time restriction for publication. Seven studies are eligible for qualitative analysis from nine studies that have the potential to be assessed. These studies measure the correlation of serum lipids (VLDL, HDL, LDL, triglycerides, total cholesterol, free cholesterol, phospholipids, free fatty acids) with semen parameters (concentration, motility, morphology, DNA fragmentation index). Although not all studies consistently report that lipids impact semen quality, this review suspects that lipids have a significant impact on sperm quality. This study implies that it is necessary to maintain lipid levels to maintain sperm quality and quality of life. However, further investigation with an observational cohort study design needs to be carried out to assess the effect of lipids on semen quality more precisely for the promotion of reproductive health care.

"Fine feathers make fine birds" - The mammalian sperm plasma membrane lipid composition and effects on assisted reproduction

The sperm plasma membrane is important in modulating many sperm functions. The sperm membrane is composed of a complex mixture of lipids including phospholipids, glycolipids and sterols. There are differences of sperm membrane composition among mammalian species with two groups differing in the most abundant polyunsaturated fatty acid (PUFA), either docosahexaenoic (ω-3 PUFA) or docosapentaenoic acid (ω-6 PUFA). During testicular and epididymal maturation, composition of the sperm plasma membrane evolves with spermatozoa gaining the capacity for fertilization. The importance of fatty acid metabolism for complete spermatogenesis has been elucidated using gene knockout mice. During epididymal transit cholesterol content decreases and PUFA content increases, conferring more fluidity properties to the sperm membrane. The relatively lesser content of antioxidant enzymes and the relatively larger content of PUFA make the spermatozoa particularly susceptible to lipid peroxidation during sperm preservation. In numerous studies, there was adding of PUFA and antioxidants to the diet of animals or to semen extenders with the aim to improve sperm membrane integrity. This review highlights the current knowledge on the sperm membrane composition and effects on sperm function in mammalian domestic animals.

TRPV1 in male reproductive system: focus on sperm function

The transient receptor potential vanilloid 1 (TRPV1) is a receptor used to perceive external noxious stimuli and participates in the regulation of various pathophysiological mechanisms in vivo by integrating multiple signals. The explosive growth in knowledge of TRPV1 stemmed from research on neuronal pain and heat sensation over the last decades and is being expanded tremendously in peripheral tissue research. The discovery that TRPV1 is functionally active in male animal and human reproductive tissues have attracted increasing attention in recent years. Indeed, many studies have indicated that TRPV1 is an endocannabinoid receptor that mediates Anandamide's regulation of sperm function. Other characteristics of the TRPV1 channel itself, such as calcium penetration and temperature sensitivity, have also been investigated, especially the possibility that TRPV1 could act as a mediator for sperm thermotaxis. In addition, some reproductive diseases appear to be related to the protective effects of TRPV1 on oxidative stress and heat stress. A better understanding of TRPV1 in these areas should provide strategies for tackling male infertility. This paper is the first to review the expression and mechanism of TRPV1 in the male reproductive system from molecular and cellular perspectives. A focus is given on sperm function, including calcium homeostasis, crosstalk with endocannabinoid system, participation in cholesterol-related sperm maturation, and thermotaxis, hoping to capture the current situation of this rapidly developing field.

PCSK9 Contributes to the Cholesterol, Glucose, and Insulin2 Homeostasis in Seminiferous Tubules and Maintenance of Immunotolerance in Testis

The PCSK9 contribution to cholesterol and immunotolerance homeostasis and response to glucose, and insulin in testis and hypophysis were studied using Pcsk9-deficient (-/-) and transgenic [Tg (PCSK9)] mice, and diabetic, obese ob/ob and db/db mice. The spermatids/spermatozoa acrosome, peritubular vessels, and epididymal adipocytes were PCSK9- and LDL-R-positive. The pro-PCSK9/PCSK9 ratio was high in interstitial tissue-fractions (ITf) and spermatozoa and low in seminiferous tubule-fractions (STf) in normal adult mice. This ratio decreased in ITf in ob/ob and db/db mice but increased in tubules in ob/ob mice. Deleting pcsk9 lowered cholesterol in serum but increased testicular cholesterol. Furthermore, HMGCoA-red, ACAT-2 and LDL-R turnover increased whereas SR-BI decreased in ITf; in tubules, ABCA1 decreased and 160 kDa LDL-R increased in Pcsk9 -/- mice. Excess testicular cholesterol could result from increased cholesterol synthesis and uptake with reduction in SR-BI-mediated efflux in ITf and from the overload of apoptotic cells, lowered ABCA1-mediated efflux and stimulated LDL-R protein synthesis in tubules in Pcsk9 -/- mice. Concomitantly with the cholesterol accumulation, tubules showed infiltrates of immune cells, elevated IL-17A and IL-17RA, and changes in the immunotolerance homeostasis. PCSK9 deficiency decreased glucose in tubules and spermatozoa while increasing insulin2 in ITf and tubules not serum. Moreover, IR-α, and IR-β augmented in tubules but decreased in the anterior pituitary; IR-α increased whereas IR-β decreased in ITf. The histology and cholesterol levels were normal in Tg (PCSK9) mouse testis. The excess cholesterol creates a milieu favorable to the action of high IL-17A and IL-17RA, the development of inflammatory conditions and self-tolerance breakdown in testis.

Adenylyl cyclase 3 deficiency results in dysfunction of blood-testis barrier during mouse spermiogenesis

Human infertility has become a global medical and social health problem. Mice deficient in type 3 adenylyl cyclase (AC3), a key enzyme that synthesizes cyclic adenosine monophosphate (cAMP), develop male infertility, although the underlying molecular mechanisms remain unknown. We performed a label-free quantitative (LFQ) proteomics analyses to identify testicular differentially expressed proteins (DEPs) and their respective biological processes. Furthermore, histological examination demonstrated that AC3 deficiency in mice led to mild impairment of spermatogenesis, including the thinning of seminiferous epithelium and local lesions in the testis. We further identified that the integrity of the blood-testis barrier (BTB) was impaired in AC3 knockout (AC3^-/-) mice accompanied with the reduction in the expression of tight junctions (TJs) and ectoplasmic specialization (ESs)-related proteins. In addition, the deletion of AC3 in mice also reduced the germ cell proliferation, increased apoptosis, and decreased lipid deposition in the seminiferous tubules. Collectively, our results revealed a role of AC3 in regulating the BTB integrity during spermatogenesis. Thus, our findings provide new perspectives for future research in male infertility.

Decabromodiphenyl ether induces male reproductive toxicity by activating mitochondrial apoptotic pathway through glycolipid metabolism dysbiosis

Decabromodiphenyl ether (BDE-209), an extensively used flame retardant, exists widely in the environment. Although male reproductive toxicity induced by BDE-209 has been reported, its mechanisms remain unclear. To explore the role of glycolipid metabolism in male reproductive toxicity and the potential mechanisms, forty male SD rats were divided into four groups and given gavage with BDE-209 at 0, 5, 50, and 500 mg/kg/d for 28 days. In vitro, the spermatogenic cell lines GC-2spd cells were divided into four groups: the control group, 32 μg/mL BDE-209 group, 32 μg/mL BDE-209 + 0.4 μM Fatostatin (the inhibitor of SREBP-1) group, and 0.4 μM Fatostatin group. Our results showed that BDE-209 decreased sperm quality and quantity, which was correlated with glycolipid metabolism dysbiosis of testis. The levels of glucose, triglyceride, and total cholesterol were negatively correlated with sperm concentration, and triglyceride and total cholesterol levels were negatively correlated with sperm motility, while positively correlated with the sperm malformation rate. Moreover, BDE-209 exposure activated the glycolipid metabolism pathways (PPARγ/RXRα/SCAP/SREBP-1) and mitochondrial apoptotic pathway, thereby inducing the apoptosis of spermatogenic cells. In vitro, BDE-209 caused triglyceride and total cholesterol disorder and apoptosis of GC-2spd cells, the lipid metabolism pathways inhibitor fatostain downregulated the elevation of triglyceride and total cholesterol concentrations, and suppressed apoptosis and the activation of the mitochondrial apoptotic pathway in GC-2spd cells caused by BDE-209. Our results indicated that BDE-209 induced male reproductive toxicity by causing glycolipid metabolism dysbiosis of testis resulting in activating of the mitochondrial apoptotic pathway in spermatogenic cells. The study provides new insight into the mechanisms of male reproductive toxicity caused by BDE-209.

The glucose-sensing transcription factor MLX balances metabolism and stress to suppress apoptosis and maintain spermatogenesis

Male germ cell (GC) production is a metabolically driven and apoptosis-prone process. Here, we show that the glucose-sensing transcription factor (TF) MAX-Like protein X (MLX) and its binding partner MondoA are both required for male fertility in the mouse, as well as survival of human tumor cells derived from the male germ line. Loss of Mlx results in altered metabolism as well as activation of multiple stress pathways and GC apoptosis in the testes. This is concomitant with dysregulation of the expression of male-specific GC transcripts and proteins. Our genomic and functional analyses identify loci directly bound by MLX involved in these processes, including metabolic targets, obligate components of male-specific GC development, and apoptotic effectors. These in vivo and in vitro studies implicate MLX and other members of the proximal MYC network, such as MNT, in regulation of metabolism and differentiation, as well as in suppression of intrinsic and extrinsic death signaling pathways in both spermatogenesis and male germ cell tumors (MGCTs).

Voluntary Exercise Attenuates Hyperhomocysteinemia, But Does not Protect Against Hyperhomocysteinemia-Induced Testicular and Epididymal Disturbances

The hyperhomocysteinemia (HHcy) is toxic to the cells and associated with several diseases. Clinical studies have shown changes in plasma concentrations of Hcy after physical exercise. This study aimed to assess the effect of HHcy on testis, epididymis and sperm quality and to investigate whether voluntary exercise training protects this system against damage caused by HHcy in Swiss mice. In this study, 48 mice were randomly distributed in the control, HHcy, physical exercise, and HHcy combined with physical exercise groups. HHcy was induced by daily administration of dl-homocysteine thiolactone via gavage throughout the experimental period. Physical exercise was performed through voluntary running on the exercise wheels. The plasma concentrations of homocysteine (Hcy) and testosterone were determined. The testes and epididymis were used to assess the sperm count, histopathology, lipoperoxidation, cytokine levels, testicular cholesterol, myeloperoxidase, and catalase activity. Spermatozoa were analyzed for morphology, acrosome integrity, mitochondrial activity, and motility. In the testes, HHcy increased the number of abnormal seminiferous tubules, reduced the tubular diameter and the height of the germinal epithelium. In the epididymis, there was tissue remodeling in the head region. Ultimately, voluntary physical exercise training reduced plasma Hcy concentration but did not attenuate HHcy-induced testicular and epididymal disturbances.

Sperm Lipid Markers of Male Fertility in Mammals

Sperm plasma membrane lipids are essential for the function and integrity of mammalian spermatozoa. Various lipid types are involved in each key step within the fertilization process in their own yet coordinated way. The balance between lipid metabolism is tightly regulated to ensure physiological cellular processes, especially referring to crucial steps such as sperm motility, capacitation, acrosome reaction or fusion. At the same time, it has been shown that male reproductive function depends on the homeostasis of sperm lipids. Here, we review the effects of phospholipid, neutral lipid and glycolipid homeostasis on sperm fertilization function and male fertility in mammals.

Male diet affects female fitness and sperm competition in human- and bat-associated lineages of the common bedbug, Cimex lectularius

Sperm performance can vary in ecologically divergent populations, but it is often not clear whether the environment per se or genomic differences arising from divergent selection cause the difference. One powerful and easily manipulated environmental effect is diet. Populations of bedbugs (Cimex lectularius) naturally feed either on bat or human blood. These are diverging genetically into a bat-associated and a human-associated lineage. To measure how male diet affects sperm performance, we kept males of two HL and BL populations each on either their own or the foreign diet. Then we investigated male reproductive success in a single mating and sperm competition context. We found that male diet affected female fecundity and changed the outcome of sperm competition, at least in the human lineage. However, this influence of diet on sperm performance was moulded by an interaction. Bat blood generally had a beneficial effect on sperm competitiveness and seemed to be a better food source in both lineages. Few studies have examined the effects of male diet on sperm performance generally, and sperm competition specifically. Our results reinforce the importance to consider the environment in which sperm are produced. In the absence of gene flow, such differences may increase reproductive isolation. In the presence of gene flow, however, the generally better sperm performance after consuming bat blood suggests that the diet is likely to homogenise rather than isolate populations.

Desmosterol Incorporation Into Ram Sperm Membrane Before Cryopreservation Improves in vitro and in vivo Fertility

Pregnancy rates in ewes are markedly low after cervical insemination with frozen-thawed sperm. Sensitivity of ram sperm to freeze-thawing is related to the lipid composition of the membrane, particularly to its low sterol content. Recently, we proved that sterol content of ram sperm can be increased by treatment with methyl-β-cyclodextrin-sterol complexes and we provided mechanistic based evidence on the differential behavior of cholesterol and desmosterol in the ram sperm membrane. In the present study, we evaluated the role of increasing cholesterol and desmosterol content of ram sperm before cryopreservation, on the extent and distribution of sterols, cryocapacitation status, acrosome integrity, DNA damage associated with apoptosis and fertility competence in vitro and in vivo of post-thawed sperm. After freeze-thawing, similar levels of sterol content were evidenced in control sperm cells and in those pre-incubated with either cholesterol or desmosterol. Still, moderately higher levels of sterols were registered in treated sperm compared to the control, indicating no physiological excess of sterols after thawing or sterol losses that exceed the control. Live cell imaging of fluorescent cholesterol evidenced the presence of sperm sub-populations differentially affected by freeze-thawing. Similar unimodal frequency profiles were observed between sterol-enriched groups, while the control exhibited a sub-population of sperm compatible with low sterol content. Tyrosine phosphorylation was significantly lower when ram sperm incorporated cholesterol compared to the control. No difference in this capacitation parameter was found between the latter and desmosterol-enriched sperm. The percentage of sperm with damaged acrosomes post-thawing, assessed by a fluorescent lectin, was reduced in sperm that incorporated sterols before freezing, irrespective of the sterol class. These results suggest that sterols exert a stabilizing effect on the acrosome. No differences were found in levels of apoptotic DNA fragmentation among experimental groups. As to fertility trials, desmosterol-enriched sperm gave rise to higher rates of in vitro activated oocytes by heterologous fertilization and to significantly lower pregnancy loss in vivo. Our research provides new insights on sterol incorporation into ram sperm prior to cryopreservation, in particular on the additional benefit of incorporating desmosterol as a strategy to improve fertility outcome.

Castration causes an increase in lysosomal size and upregulation of cathepsin D expression in principal cells along with increased secretion of procathepsin D and prosaposin oligomers in adult rat epididymis

In the epididymis, lysosomal proteins of the epithelial cells are normally targeted from the Golgi apparatus to lysosomes for degradation, although their secretion into the epididymal lumen has been documented and associated with sperm maturation. In this study, cathepsin D (CatD) and prosaposin (PSAP) were examined in adult epididymis of control, and 2-day castrated rats without (Ct) and with testosterone replacement (Ct+T) to evaluate their expression and regulation within epididymal epithelial cells. By light microscope-immunocytochemistry, a quantitative increase in size of lysosomes in principal cells of Ct animals was noted from the distal initial segment to the proximal cauda. Androgen replacement did not restore the size of lysosomes to control levels. Western blot analysis revealed a significant increase in CatD expression in the epididymis of Ct animals, which suggested an upregulation of its expression in principal cells; androgens restored levels of CatD to that of controls. In contrast, PSAP expression in Ct animals was not altered from controls. Additionally, an increase in procathepsin D levels was noted from samples of the epididymal fluid of Ct compared to control animals, accompanied by an increased complex formation with PSAP. Moreover, an increased oligomerization of prosaposin was observed in the epididymal lumen of Ct rats, with changes reverted to controls in Ct+T animals. Taken together these data suggest castration causes an increased uptake of substrates that are acted upon by CatD in lysosomes of principal cells and in the lumen by procathepsin D. These substrates may be derived from apoptotic cells noted in the lumen of proximal regions and possibly by degenerating sperm in distal regions of the epididymis of Ct animals. Exploring the mechanisms by which lysosomal enzymes are synthesized and secreted by the epididymis may help resolve some of the issues originating from epididymal dysfunctions with relevance to sperm maturation.

Sperm Cholesterol Content Modifies Sperm Function and TRPV1-Mediated Sperm Migration

Transient receptor potential channels-vanilloid receptor 1 (TRPV1) regulates thermotaxis in sperm-oriented motility. We investigated the role of membrane cholesterol (Chol) on TRPV1-mediated human sperm migration. Semen samples were obtained from five normozoospemic healthy volunteers. Sperm membrane Chol content, quantified by liquid chromatography-mass spectrometry, was modified by incubating cells with 2-hydroxypropyl-ß-cyclodextrin (CD) or the complex between CD and Chol (CD:Chol). The effect on sperm migration on a 10 μM capsaicin gradient (CPS), a TRPV1 agonist, was then investigated. Motility parameters were evaluated by Sperm Class Analyser. Intracellular calcium concentration and acrosome reaction were measured by staining with calcium orange and FITC-conjugated anti-CD46 antibody, respectively. TRPV1-Chol interaction was modelled by computational molecular-modelling (MM). CD and CD:Chol, respectively, reduced and increased membrane Chol content in a dose-dependent manner, resulting in a dose-dependent increase and reduction of sperm migration in a CPS gradient. MM confirmed a specific interaction of Chol with a TRPV1 domain that appeared precluded to the Chol epimer epicholesterol (Epi-Chol). Accordingly, CD:Epi-Chol was significantly less efficient than CD:Chol, in reducing sperm migration under CPS gradient. Chol inhibits TRPV1-mediated sperm function by directly interacting with a consensus sequence of the receptor.

Stress response pathways in the male germ cells and gametes

The unfolded protein response (UPR) is a conserved and essential cellular pathway involved in protein quality control that is activated in response to several cellular stressors such as diseases states, ageing, infection and toxins. The cytosol, endoplasmic reticulum (ER) and mitochondria are continuously exposed to new proteins and in situations of aberrant protein folding; one of three lines of defence may be activated: (i) heat-shock response, (ii) mitochondrial UPR and (iii) ER UPR. These pathways lead to different signal transduction mechanisms that activate or upregulate transcription factors that, in turn, regulate genes that increase the cell's ability to correct the conformation of poorly folded proteins or, ultimately, lead to apoptosis. Despite the recent progress in understanding such biological processes, few studies have focused on the implications of the UPR in male infertility, highlighting the need for a first approach concerning the presence of these components in the male reproductive system. In testis, there is a high rate of protein synthesis, and the UPR mechanisms are well described. However, the presence of these mechanisms in spermatozoa, apparently transcriptionally inactive cells, is contentious, and it is unclear how sperm cells deal with stress. Here, we review current concepts and mechanisms of the UPR and highlight the relevance of these stress response pathways in male fertility, especially the presence and functional activation of those components in male germinal cells and spermatozoa.

Evidence that glycosaminoglycan storage and collagen deposition in the cauda epididymidis does not impair sperm viability in the Mucopolysaccharidosis type I mouse model

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disease caused by a deficiency of the lysosomal hydrolase, α-L-iduronidase (IDUA). IDUA degrades heparan and dermatan sulfates, two types of glycosaminoglycan (GAG), important signalling and structural molecules of the extracellular matrix. Because many cell types store GAGs, MPS I has been investigated in human and animal models. Enzyme replacement therapy is available for MPS I patients and has improved their life expectancy, allowing them to achieve reproductive age. The aim of this study was to evaluate epididymal and sperm morphology and function in a murine model of MPS I. We used C57BL Idua+/+ and Idua-/- adult male mice (6 months old) to investigate epididymal morphology, sperm ultrastructure, GAG characterisation and mating competence. Epithelial GAG storage, especially in the cauda epididymidis, was seen in Idua-/- mice. Regardless of the morphologic change and GAG storage found in the cauda epididymis, sperm morphology and motility were normal, similar to wild types. In the interstitium, vacuolated cells were found in addition to deposits of GAGs. Mating was not impaired in Idua-/- males and litter sizes were similar between groups. At the time point of the disease evaluated, the deficiency in IDUA affected the morphology of the epididymis in male Idua-/- mice, whereas sperm appearance and motility and the male's capacity to mate and impregnate females were preserved.

Gene expression and functional abnormalities in XX/Sry Leydig cells

The SRY gene induces testis development even in XX individuals. However, XX/Sry testes fail to produce mature sperm, due to the absence of Y chromosome carrying genes essential for spermatogenesis. XX/Sry Sertoli cells show abnormalities in the production of lactate and cholesterol required for germ cell development. Leydig cells are essential for male functions through testosterone production. However, whether XX/Sry adult Leydig cells (XX/Sry ALCs) function normally remains unclear. In this study, the transcriptomes from XY and XX/Sry ALCs demonstrated that immediate early and cholesterogenic gene expressions differed between these cells. Interestingly, cholesterogenic genes were upregulated in XX/Sry ALCs, although downregulated in XX/Sry Sertoli cells. Among the steroidogenic enzymes, CYP17A1 mediates steroid 17α-hydroxylation and 17,20-lyase reaction, necessary for testosterone production. In XX/Sry ALCs, the latter reaction was selectively decreased. The defects in XX/Sry ALCs, together with those in the germ and Sertoli cells, might explain the infertility of XX/Sry testes.

Grape seed extract improved the fertility-enhancing effect of atorvastatin in high-fat diet-induced testicular injury in rats: involvement of antioxidant and anti-apoptotic effects

Objectives

Reduced male fertility is highly prevalent with hypercholesterolaemia. Though statins are drugs of choice for hypercholesterolaemia, their effect on male fertility is still controversial and dose-dependent. Grape seed extract (GSE) possess hypocholesterolemic and testicular protective effects. Thus, this study aimed to investigate the effects of low-dose atorvastatin (ATV) on male infertility in hypercholesterolaemic rats and assess the additional value of combining ATV with GSE.

Methods

Male rats were randomized into four groups. The normal group was fed a standard diet. The remaining groups were fed a high-fat diet (HFD) for 1 month to induce hypercholesterolaemia. Two HFD groups were administered either ATV (1 mg/kg) alone or combined with GSE (200 mg/kg) orally for 65 days, while the third group served as HFD control.

Key findings

Treatment with ATV or ATV/GSE attenuated dyslipidemia-induced alteration in serum HDL-cholesterol, LDL-cholesterol, and total cholesterol. ATV enhanced serum testosterone, sperm count and motility and fertility index. The effect on testosterone and sperm count was more pronounced by ATV/GSE. Moreover, ATV reduced testicular malondialdehyde, nitric oxide, caspase-9 and caspase-3 while elevated reduced glutathione and superoxide dismutase along with catalase activity. Noteworthy, GSE/ATV induced more powerful antioxidant and anti-apoptotic effects.

Conclusion

GSE enhanced ATV’s protective effect against hypercholesterolaemia-induced infertility via antioxidant and anti-apoptotic mechanisms.

Social status and ejaculate composition in the house mouse

Sperm competition theory predicts that males should tailor ejaculates according to their social status. Here, we test this in a model vertebrate, the house mouse (Mus musculus domesticus), combining experimental data with a quantitative proteomics analysis of seminal fluid composition. Our analyses reveal that both sperm production and the composition of proteins found in seminal vesicle secretions differ according to social status. Dominant males invested more in ejaculate production overall. Their epididymides contained more sperm than those of subordinate or control males, despite similar testes size between the groups. Dominant males also had larger seminal vesicle glands than subordinate or control males, despite similar body size. However, the seminal vesicle secretions of subordinate males had a significantly higher protein concentration than those of dominant males. Moreover, detailed proteomic analysis revealed subtle but consistent differences in the composition of secreted seminal vesicle proteins according to social status, involving multiple proteins of potential functional significance in sperm competition. These findings have significant implications for understanding the dynamics and outcome of sperm competition, and highlight the importance of social status as a factor influencing both sperm and seminal fluid investment strategies. This article is part of the theme issue 'Fifty years of sperm competition'.

Proton MR Spectroscopy in Assessing the Biochemical Milieu of Human Testes

Proton magnetic resonance spectroscopy (MRS), considered a connection between metabolism and anatomic and functional information provided by standard MRI, gives information on various tissue metabolites and their pathologic changes. Recently, proton MRS has been added as an adjunct tool to the multiparametric protocol of scrotal MRI, providing a new insight into the extremely complex biochemical milieu of normal and abnormal testes. This article reviews proton MR spectra of normal testes, showing age and bilateralism dependence. Disturbances of various metabolic pathways in testes of infertile men resulting in alterations of metabolite peaks are discussed. Preliminary data on proton MR spectra of testicular mass lesions are presented. LEVEL OF EVIDENCE: 5. TECHNICAL EFFICACY STAGE: 5.

Role of cholesterol metabolism in the anticancer pharmacology of selective estrogen receptor modulators

Selective estrogen receptor modulators (SERMs) are a class of compounds that bind to estrogen receptors (ERs) and possess estrogen agonist or antagonist actions in different tissues. As such, they are widely used drugs. For instance, tamoxifen, the most prescribed SERM, is used to treat ERα-positive breast cancer. Aside from their therapeutic targets, SERMs have the capacity to broadly affect cellular cholesterol metabolism and handling, mainly through ER-independent mechanisms. Cholesterol metabolism reprogramming is crucial to meet the needs of cancer cells, and different key processes involved in cholesterol homeostasis have been associated with cancer progression. Therefore, the effects of SERMs on cholesterol homeostasis may be relevant to carcinogenesis, either by contributing to the anticancer efficacy of these compounds or, conversely, by promoting resistance to treatment. Understanding these aspects of SERMs actions could help to design more efficacious therapies. Herein we review the effects of SERMs on cellular cholesterol metabolism and handling and discuss their potential in anticancer pharmacology.

Sperm methylome alterations following yoga-based lifestyle intervention in patients of primary male infertility: A pilot study

A majority of the cases of primary male infertility are idiopathic with the underlying molecular mechanisms contributing to the pathophysiology as yet unknown. Effects of the environment can alter the sperm epigenome thereby impacting male reproductive health. Epigenetic mechanisms are crucial to understanding health and disease, and methylome alterations are now known to have far-reaching clinical implications. Here, we report the results from our pilot study, a first of its kind analysis of the effect of the traditional practice of yoga on human sperm quality. We find marked improvement in sperm characteristics in patients of idiopathic male infertility following a supervised 21-day yoga regimen. Furthermore, next-generation sequencing-based methylome analysis reveals alterations in the sperm epigenome of these patients. We find that the practice of yoga is associated with DNA methylation changes at nearly 400 genes, 147 of which were hypermethylated while 229 were hypomethylated. These included promoters of several genes linked to maintenance of fertility and genomic integrity. This novel piece of work draws a direct link between positive lifestyle practices and male reproductive health.

First Insights on the Presence of the Unfolded Protein Response in Human Spermatozoa

The unfolded protein response (UPR) is involved in protein quality control and is activated in response to several stressors. Although in testis the UPR mechanisms are well described, their presence in spermatozoa is contentious. We aimed to investigate the presence of UPR-related proteins in human sperm and the impact of oxidative stress induction in UPR activation. To identify UPR-related proteins in human sperm, a bioinformatic approach was adopted. To explore the activation of UPR, sperm were exposed to hydrogen peroxide (H₂O₂) and motility, vitality, and the levels of UPR-related proteins were assessed. We identified 97 UPR-related proteins in human sperm and showed, for the first time, the presence of HSF1, GADD34, and phosphorylated eIF2α. Additionally, the exposure of human sperm to H₂O₂ resulted in a significant decrease in sperm viability and motility and an increase in the levels of HSF1, HSP90, HSP60, HSP27, and eIF2α; all proteins involved in sensing and response to unfolded proteins. This study gave us a first insight into the presence of UPR mechanisms in the male gamete. However, the belief that sperm are devoid of transcription and translation highlight the need to clarify if these pathways are activated in sperm in the same way as in somatic cells.

Liver X Receptors and Male (In)fertility

Liver X receptors (LXRs) are ligand-dependent transcription factors acting as ‘cholesterol sensors’ to regulate lipid homeostasis in cells. The two isoforms, LXRα (NR1H3) and LXRβ (NR1H2), are differentially expressed, with the former expressed predominantly in metabolically active tissues and the latter more ubiquitously. Both are activated by oxidised cholesterol metabolites, endogenously produced oxysterols. LXRs have important roles in lipid metabolism and inflammation, plus a number of newly emerging roles. They are implicated in regulating lipid balance in normal male reproductive function and may provide a link between male infertility and lipid disorders and/or obesity. Studies from Lxr knockout mouse models provide compelling evidence to support this. More recently published data suggest distinct and overlapping roles of the LXR isoforms in the testis and recent evidence of a role for LXRs in human male fertility. This review summarises the current literature and explores the likely link between LXR, lipid metabolism and male fertility as part of a special issue on Liver X receptors in International Journal of Molecular Sciences.

Alteration of Cholesterol Sulfate/Seminolipid Ratio in Semen Lipid Profile of Men With Oligoasthenozoospermia

The reduction of sperm motility and count, or oligoasthenozoospermia, is one of the major causes of reduced fertility or infertility in men. Lipid composition of spermatozoa is important in determining their functional characteristics, in particular on motility, acrosomal exocytosis or fusogenic properties of the sperm. Here we investigated the levels of semen lipids in 11 infertile patients with severe oligoasthenozoospermia and 9 normozoospermic subjects with normal motility values. Sperm polar and neutral lipids were analyzed by thin-layer chromatography (TLC) and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Semen of patients with oligoasthenozoospermia showed a reduction of the degree of fatty acid unsaturation in the phospholipids chains that might affect the membrane fluidity. Furthermore, a significant higher cholesterol sulfate/seminolipid ratio was found in semen of oligoasthenozoospermic patients than in subjects with normal motility values, suggesting a critical role of sulfolipids in semen quality. The results may facilitate the understanding of the role of lipids on male fertility and offer interesting perspectives to find innovative treatments for oligoasthenozoospermia.

Molecular Evaluation of Impacted Reproductive Physiology in Fathead Minnow Testes Provides Mechanistic Insights into Insensitive Munitions Toxicology

Previous toxicological investigations of the insensitive munition (IM), 3-nitro-1,2,4-triazol-5-one (NTO), demonstrated histopathological and physiological impacts in mammalian testes. The implications of these findings for fish was unknown, therefore we investigated the effects of chronic (21 day) exposures to NTO and an NTO-containing IM formulation called IMX-101 (composed of 2,4-dinitroanisole (DNAN), nitroguanidine (NQ), and NTO) in adult male fathead minnows to assess if impacts on testes were conserved. The NTO exposure caused no significant mortality through the maximum exposure concentration (720 mg/L, measured), however NTO elicited testicular impacts causing significant asynchrony in spermatogenesis and necrosis in secondary spermatocytes at the two highest exposure concentrations (383 mg/L and 720 mg/L) and testicular degeneration at the highest exposure. Microarray-based transcriptomics analysis identified significant enrichment of steroid metabolism pathways and mTORC-signal control of spermatogonia differentiation in NTO exposures each having logical connections to observed asynchronous spermatogenesis. Additionally, NTO impaired transcriptional expression for genes supporting sperm structural and flagellar development including sperm-associated antigen 6 (Spag6). These functional transcriptomic responses are hypothesized contributors to impacted reproductive physiology in NTO exposures that ultimately lead to reductions in spermatozoa. In contrast to NTO, the IMX-101 formulation elicited significant mortality at the two highest exposure concentrations of 25.2 and 50.9 mg/L (DNAN nominal + NTO measured + NQ measured). Unlike NTO and NQ, the DNAN component of the IMX-101 formulation underwent significant transformation in the 21d exposure. From previous investigations, neither NTO nor NQ caused mortality in fish at >1000 mg/L suggesting that mortality in the present study arose from DNAN / DNAN-attributable transformation products. The 12.6 mg/L IMX-101 exposure caused significant sublethal impacts on testes including sperm necrosis, interstitial fibrosis, and Sertoli-like cell hyperplasia. Transcriptional profiles for IMX-101 indicated significant enrichment on multiple signaling pathways supporting spermatogenesis, mitosis / meiosis, and flagellar structure, all logically connected to observed sperm necrosis. Additionally, pronounced transcriptional increases within the PPARα-RXRα pathway, a known DNAN target, has been hypothesized to correspond to Sertoli cell hyperplasia, presumably as a compensatory response to fulfill the nurse-function of Sertoli cells during spermatogenesis. Overall, the transcriptional results indicated unique molecular responses for NTO and IMX-101. Regarding chemical hazard, NTO impacted testes and impaired spermatogenesis, but at high exposure concentrations (≥ 192 mg/L), whereas the IMX-101 formulation, elicited mortality and impacts on reproductive physiology likely caused by DNAN and its transformation products present at concentrations well below the NTO-component concentration within the IMX-101 mixture formulation.

Impairment of sperm maturation and capacitation due to diet-dependent cholesterol overload

BACKGROUND

Lipid metabolic disorders (dyslipidemia) are constantly increasing in occidental societies and lead to the development of pathologies such as obesity, diabetes, and metabolic syndrome. It has been demonstrated that dyslipidemia can alter the reproductive function. Animal models have recently been used to show that the offspring of dyslipidemic males could also develop such pathologies and that the transgenerational transmission involved post-testicular sperm maturation. These data targeted the essential role of male gamete epididymal maturation and its importance for the health of the offspring.

OBJECTIVES

This publication summarizes in the first place experimental data obtained using a mouse model of dyslipidemia-induced post-testicular infertility, knockout mice for the two isoforms of the 'Liver X Receptors' (Lxrα;β^-/- ), the major regulators of cholesterol homeostasis. The impact of a high cholesterol diet (HCD) on the protein YWHAZ (14-3-3 ζ or tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein Zeta) was also investigated in our model.

MATERIALS AND METHODS

In our mouse model, when young fertile Lxrα;β^-/- males aged three months were fed four weeks with a HCD, they developed an epididymal phenotype leading to infertility. The level of sperm YWHAZ was evaluated by Western blot and its tyrosine phosphorylation state by immunoprecipitation followed by Western blot.

RESULTS

Our data revealed that sperm lipid composition and structure were altered, leading to defects of the capacitation-associated signaling pathway. They also showed that both the level and the tyrosine phosphorylation state of YWHAZ were affected by the HCD in sperm cells from Lxrα;β^-/- males.

DISCUSSION AND CONCLUSION

YWHAZ could be a new important regulator of capacitation-associated tyrosine phosphorylation and a marker of dyslipidemia-induced infertility.

Functional importance of palmitoyl protein thioesterase 1 (PPT1) expression by Sertoli cells in mediating cholesterol metabolism and maintenance of sperm quality

Sertoli cells are a type of nurse cell in the seminiferous epithelium that are crucial for sustaining spermatogenesis by extending nutritional and energy support to the developing germ cells. Dysfunction of Sertoli cells could cause disordered spermatogenesis and reduced fertility in males. In this study, we focused on the expression and function of palmitoyl protein thioesterase 1 (PPT1), a lysosomal depalmitoylating enzyme, in Sertoli cells. Here, we show that PPT1 expression in Sertoli cells is responsive to cholesterol treatment and that specific knockout of Ppt1 in Sertoli cells causes male subfertility associated with poor sperm quality and a high ratio of sperm deformity. Specifically, Ppt1 deficiency leads to poor cell variably accompanied with abnormal lysosome accumulation and increased cholesterol levels in Sertoli cells. Further, Ppt1 deficiency results in poor adhesion of developing germ cells to Sertoli cells in the seminiferous epithelium, which is likely to be responsible for the reduced male fertility as a consequence of declines in sperm count and motility as well as a high incidence of sperm head deformity. In summary, PPT1 affects sperm quality and male fertility through regulating lysosomal function and cholesterol metabolism in Sertoli cells.

Sperm can act as vectors for HIV-1 transmission into vaginal and cervical epithelial cells

PROBLEM

Sperm are the major cells in semen. Human sperm possess a number of HIV-1 gp120 binding ligands including sulfogalactosylglycerolipid (SGG). However, the mechanisms of how sperm capture HIV-1 onto their surface are unclear. Furthermore, the ability of sperm to deliver HIV-1 to vaginal/cervical epithelial cells lining the lower female reproductive tract, as a first step in HIV-1 transmission, needs to be determined.

METHOD OF STUDY

Sperm from healthy donors were incubated with dual-tropic HIV-1_CS204 (clinical isolate), and virus capture was determined by p24 antigen ELISA. The involvement of SGG in HIV-1 capture was assessed by determining K_d values of HIV-1 gp120-SGG binding as well as computational docking of SGG to the gp120 V3 loop. The ability of sperm-associated HIV-1 to infect peripheral blood mononuclear cells (PBMCs) and TZM-bl indicator cells was determined. Lastly, infection of vaginal (Vk2/E6E7), ectocervical (Ect1/E6E7), and endocervical (End1/E6E7) epithelial cells mediated by HIV-1-associated sperm was evaluated.

RESULTS

Sperm were able to capture HIV-1 in a dose-dependent manner, and the capture reached a maximum within 5 minutes. Captured HIV-1, however, could be removed from sperm by Percoll-gradient centrifugation. Affinity of gp120 for SGG was substantial, implicating sperm SGG in HIV-1 capture. Sperm-associated HIV-1 could productively infect PBMCs and TZM-bl cells, and was capable of being transmitted into vaginal/cervical epithelial cells.

CONCLUSION

Sperm are able to capture HIV-1, which remains infectious and is able to be transmitted into vaginal/cervical epithelial cells, a result indicating the importance of sperm in HIV transmission.

Morbid obesity-related changes in the expression of lipid receptors, transporters, and HSL in human sperm

OBJECTIVE

To study the location and expression of receptors (SR-BI/CLA-1, SR-BII, and LDLr) and transporter (ABCA1) involved in uptake and efflux of cholesterol in human spermatozoa and assess whether obesity alters its location/expression and whether this could be related to infertility.

DESIGN

Observational study.

SETTING

None PATIENT(S): Ten controls and 20 obese patients.

INTERVENTION(S)

Anthropometric parameters. Serum and semen samples were collected.

MAIN OUTCOME MEASURE(S)

Spermatozoon concentration, immunolocalization, and protein expression in semen.

RESULTS

Spermatozoon concentration and motility was decreased in morbidly obese patients. SR-BI/CLA-1, SR-BII, LDLr, and ABCA1 are located in the spermatozoon cell membrane and the localization does not change between obese patients and controls. Control spermatozoa showed high SR-BI expression, and less expression for the rest of the receptors analyzed, indicating that SR-BI/CLA-1 is relevant in human spermatozoon cholesterol uptake/efflux. On the contrary, spermatozoa of obese patients showed less SR-BI/CLA-1 expression than controls, and more intense positive staining for SR-BII, LDLr, and ABCA1. Finally, human sperm expresses the 130- and 82-kDa hormone-sensitive lipase (HSL) isoforms. The 130-kDa isoform is expressed in the control sperm, and the expression disappears in the obese patients.

CONCLUSION(S)

The presence of lipid receptors/transporters and HSL in human spermatozoa suggests their role in the process of maturation/capacitation. The changes in the expression of lipid receptors/transporters and the lack of the 130-kDa HSL isoform in obese patients prevent the hydrolysis of cholesterol esters internalized by these receptors, and favor their accumulation in the cytoplasm of the spermatozoa that could contribute to lipotoxicity and infertility.

Prenatal Bisphenol A Exposure in Mice Induces Multitissue Multiomics Disruptions Linking to Cardiometabolic Disorders

The health impacts of endocrine-disrupting chemicals (EDCs) remain debated, and their tissue and molecular targets are poorly understood. In this study, we leveraged systems biology approaches to assess the target tissues, molecular pathways, and gene regulatory networks associated with prenatal exposure to the model EDC bisphenol A (BPA). Prenatal BPA exposure at 5 mg/kg/d, a dose below most reported no-observed-adverse-effect levels, led to tens to thousands of transcriptomic and methylomic alterations in the adipose, hypothalamus, and liver tissues in male offspring in mice, with cross-tissue perturbations in lipid metabolism as well as tissue-specific alterations in histone subunits, glucose metabolism, and extracellular matrix. Network modeling prioritized main molecular targets of BPA, including Pparg, Hnf4a, Esr1, Srebf1, and Fasn as well as numerous less studied targets such as Cyp51 and long noncoding RNAs across tissues, Fa2h in hypothalamus, and Nfya in adipose tissue. Lastly, integrative analyses identified the association of BPA molecular signatures with cardiometabolic phenotypes in mouse and human. Our multitissue, multiomics investigation provides strong evidence that BPA perturbs diverse molecular networks in central and peripheral tissues and offers insights into the molecular targets that link BPA to human cardiometabolic disorders.

Rosiglitazone ameliorates palmitic acid-induced cytotoxicity in TM4 Sertoli cells

The Sertoli cell is the only somatic cell within the seminiferous tubules, and is vital for testis development and spermatogenesis. Rosiglitazone (RSG) is a member of the thiazolidinedione family and is a peroxisome proliferator-activated receptor-γ (PPARγ) agonist. It has been reported that RSG protects various types of cells from fatty acid-induced damage. However, whether RSG serves a protective role in Sertoli cells against palmitic acid (PA)-induced toxicity remains to be elucidated. Therefore, the aim of the present study was to investigate the effect of RSG on PA-induced cytotoxicity in Sertoli cells. MTT assay and Oil Red O staining revealed that RSG ameliorated the PA-induced decrease in TM4 cell viability, which was accompanied by an alleviation of PA-induced lipid accumulation in cells. In primary mouse Sertoli cells, RSG also showed similar protective effects against PA-induced lipotoxicity. Knockdown of PPARγ verified that RSG exerted its protective role in TM4 cells through a PPARγ-dependent pathway. To evaluate the mechanism underlying the protective role of RSG on PA-induced lipotoxicity, the present study analyzed the effects of RSG on PA uptake, and the expression of genes associated with both fatty acid oxidation and triglyceride synthesis. The results demonstrated that although RSG did not affect the endocytosis of PA, it significantly elevated the expression of carnitine palmitoyltransferase (CPT)-1A, a key enzyme involved in fatty acid oxidation, which indicated that the protective effect of RSG may have an important role in fatty acid oxidation. On the other hand, the expression of CPT1B was not affected by RSG. Moreover, the expression levels of diacylglycerol O-acyltransferase (DGAT)-1 and DGAT2, both of which encode enzymes catalyzing the synthesis of triglycerides, were not suppressed by RSG. The results indicated that RSG reduced PA-induced lipid accumulation by promoting fatty acid oxidation mediated by CPT1A. The effect of RSG in protecting cells from lipotoxicity was also found to be specific to Sertoli cells and hepatocytes, and not to other cell types that do not store excess lipid in large quantities, such as human umbilical vein endothelial cells. These findings provide insights into the cytoprotective effects of RSG on Sertoli cells and suggest that PPARγ activation may be a useful therapeutic method for the treatment of Sertoli cell dysfunction caused by dyslipidemia.

SULFATION PATHWAYS: Expression of SULT2A1, SULT2B1 and HSD3B1 in the porcine testis and epididymis

In the porcine testis, in addition to estrogen sulfates, the formation of numerous sulfonated neutral hydroxysteroids has been observed. However, their functions and the underlying synthetic pathways are still widely unclear. To obtain further information on their formation in postpubertal boars, the expression of sulfotransferases considered relevant for neutral hydroxysteroids (SULT2A1, SULT2B1) was investigated in the testis and defined segments of the epididymis applying real-time RT-qPCR, Western blot and immunohistochemistry (IHC). Sulfotransferase activities were assessed in tissue homogenates or cytosolic preparations applying dehydroepiandrosterone and pregnenolone as substrates. A high SULT2A1 expression was confirmed in the testis and localized in Leydig cells by IHC. In the epididymis, SULT2A1 expression was virtually confined to the body. SULT2B1 expression was absent or low in the testis but increased significantly along the epididymis. Immunohistochemical observations indicate that both enzymes are secreted into the ductal lumen via an apocrine mechanism. The results from the characterization of expression patterns and activity measurements suggest that SULT2A1 is the prevailing enzyme for the sulfonation of hydroxysteroids in the testis, whereas SULT2B1 may catalyze the formation of sterol sulfates in the epididymis. In order to obtain information on the overall steroidogenic capacity of the porcine epididymis, the expression of important steroidogenic enzymes (CYP11A1, CYP17A1, CYP19, HSD3B1, HSD17B3, SRD5A2) was monitored in the defined epididymal segments applying real-time RT-qPCR. Surprisingly, in addition to a high expression of SRD5A2 in the epididymal head, a substantial expression of HSD3B1 was detected, which increased along the organ.

Proteomic identification of turkey (Meleagris gallopavo) seminal plasma proteins

SDS-PAGE combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and 2-dimensional electrophoresis (2DE) combined with matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (MALDI TOF/TOF) were applied to characterize the turkey seminal plasma proteome. LC-MS/MS led to the identification of 175 proteins, which were classified according to their function and to corresponding biochemical pathways. Using 2DE and MALDI TOF/TOF, 34 different turkey seminal plasma proteins could be identified, of which 20 were found in more than one spot, indicating different proteoforms of these proteins. For validation, antibodies against turkey albumin and ovoinhibitor as well as sperm acrosin were used in 2DE Western blots experiments. The bioinformatic analysis of the results indicates that turkey seminal plasma proteins may be involved in regulation of lipid metabolism [liver X receptor/retinoid X receptor (LXR/RXR) activation and farnesoid X receptor/retinoid X receptor (FXR/RXR) activation pathways)], endocytic entry of proteins and lipids at the plasma membrane (clathrin-mediated endocytosis pathway), and defense against pathogens (acute phase response signaling pathway) and energy production (glycolysis and gluconeogenesis). Moreover, a comparative meta-analysis of seminal plasma proteomes from other species indicated the presence of proteins specific for avian reproduction, but distinct differences between turkey and chicken seminal plasma proteomes were detected. The results of our study provide basic knowledge of the protein composition of turkey seminal plasma highlighting important physiological pathways which may play crucial roles in the sperm environment after ejaculation. This knowledge can be the basis to further develop procedures improving the reproduction of farmed turkeys.