Morphological analysis of germ cell apoptosis during postnatal testis development in normal and Hsp 70-2 knockout mice

Single-cell transcriptomic and cross-species comparison analyses reveal distinct molecular changes of porcine testes during puberty

The pig is an important model for studying human diseases and is also a significant livestock species, yet its testicular development remains underexplored. Here, we employ single-cell RNA sequencing to characterize the transcriptomic landscapes across multiple developmental stages of Bama pig testes from fetal stage through infancy, puberty to adulthood, and made comparisons with those of humans and mice. We reveal an exceptionally early onset of porcine meiosis shortly after birth, and identify a distinct subtype of porcine spermatogonia resembling transcriptome state 0 spermatogonial stem cells identified in humans, which were previously thought to be primate specific. We also discover the persistent presence of proliferating progenitors for myoid cells in postnatal testes. The regulatory roles of Leydig cell steroidogenesis and estrogen synthesis in supporting cell lineages are also explored, including the potential impact of estrogen on Sertoli cell maturation and spermatogenesis. Overall, this study offers valuable insights into porcine testicular development, paving the way for future research in reproductive biology, advancements in agricultural breeding, and potential applications in translational medicine.

Mapping the human sperm proteome - novel insights into reproductive research

INTRODUCTION

Spermatozoa are highly specialized cells with unique morphology. In addition, spermatozoa lose a considerable amount of cytoplasm during spermiogenesis, when they also compact their DNA, resulting in a transcriptionally quiescent cell. Throughout the male reproductive tract, sperm will acquire proteins that enable them to interact with the female reproductive tract. After ejaculation, proteins undergo post-translational modifications for sperm to capacitate, hyperactivate and fertilize the oocyte. Many proteins have been identified as predictors of male infertility, and also investigated in diseases that compromise reproductive potential.

AREAS COVERED

In this review we proposed to summarize the recent findings about the sperm proteome and how they affect sperm structure, function, and fertility. A literature search was performed using PubMed and Google Scholar databases within the past 5 years until August 2022.

EXPERT OPINION

Sperm function depends on protein abundance, conformation, and PTMs; understanding the sperm proteome may help to identify pathways essential to fertility, even making it possible to unravel the mechanisms involved in idiopathic infertility. In addition, proteomics evaluation offers knowledge regarding alterations that compromise the male reproductive potential.

Elderberry Diet Restores Spermatogenesis in the Transient Scrotal Hyperthermia-Induced Mice

Over the past years, several studies have also reported the adverse effects of hyperthermia on normal testicular tissues in several species including mice, rats, and humans. These deleterious impacts include temporarily drop in relative weight of testis along with a temporary partial or complete infertility. Sambucus nigra, also known as elderberry or sweet elder, is a source of bioactive compounds that has drawn growing attention for its potential beneficial effects in preventing and treating several diseases. This experimental research divided 30 mice into the following three groups: (1) control, (2) hyperthermia, and (3) hyperthermia receiving elderberry diet for 35 days. Scrotal hyperthermia was induced by water bath with 43 °C for 30 min. Then, the mice were euthanized, and their sperm samples were collected for sperm parameters analysis. Then, we took the testis samples for histopathological experimentations, immunohistochemistry against TNF-α and caspase-3 and serum testosterone, FSH and LH levels. Our outputs indicated that elderberry diet could largely improve the sperms parameters and stereological parameters, like spermatogonia, primary spermatocyte, round spermatid, and Leydig cells together with an increasing level of the serum testosterone compared to the scrotal hyperthermia induced mice. In addition, it was found that the expression of TNF-α and caspase-3 significantly decreased in the treatment groups by elderberry diet compared to the scrotal hyperthermia-induced mice. In conclusion, it could be concluded that elderberry diet may be regarded as an alternative treatment for improving the spermatogenesis process in the scrotal hyperthermia induced mice.

Heat Shock Factors in Protein Quality Control and Spermatogenesis

Proper regulation of cellular protein quality control is crucial for cellular health. It appears that the protein quality control machinery is subjected to distinct regulation in different cellular contexts such as in somatic cells and in germ cells. Heat shock factors (HSFs) play critical role in the control of quality of cellular proteins through controlling expression of many genes encoding different proteins including those for inducible protein chaperones. Mammalian cells exert distinct mechanism of cellular functions through maintenance of tissue-specific HSFs. Here, we have discussed different HSFs and their functions including those during spermatogenesis. We have also discussed the different heat shock proteins induced by the HSFs and their activities in those contexts. We have also identified several small molecule activators and inhibitors of HSFs from different sources reported so far.

Efficacy of Ficus carica leaf extract on morphological and molecular behavior of mice germ stem cells

Infertility is one of the most prevalent health disorders in reproductive-age males and females. Ficus carica (Fc), an herbal plant, has been used traditionally for the treatment of different diseases such as infertility especially in Iranian folk medicine. This study examined the effects of Fc leaf extract on the proliferation of mice spermatogonial stem cells (SSCs). Phenolic, flavonoid content, major polyphenolic compounds and antioxidant activity of the extract was evaluated respectively by Folin-Ciocateu, aluminum chloride, HPLC and the FRAP and DPPH methods. Testicular cells of neonate mice were extracted and their identity was confirmed using cytokeratin for Sertoli and Oct-4, CDHI and PLZF for SSCs. Effects of Fc (0.0875, 0.175, 0.35, 0.71 and 1.42 mg/ml) was evaluated at third, 7th, 9th and 14th days of culture by colony assay. The expression of the Mvh, GFRα1 and Oct-4 genes and the viability and proliferation of cultured cells was assessed at the end of the culture period. The extract has a rich phenolic and flavonoid content such as Rutin, Psoralen, Bergapten and Caffeoylmalic acid using HPLC analysis. It also had a potent reducing and radical scavenging activity. Morphology of colonies was similar in all groups. Higher viability, proliferation, colony number and diameter of SSCs was seen in the presence of Fc leaf extract in a dose-dependent manner so that higher number and diameter of colonies were observed in two higher doses of 0.71 and 1.42 mg/ml, separately for each time point relative to other groups. The Mvh, Oct-4 and GFRα1 genes expression had no significant differences between groups. It seems that Fc leaf extract not only had no any cytotoxic effects on the viability and proliferation of SSCs but also support their stemness state. So, this culture system can be employed for enrichment of germ stem cells for use in clinical applications.

Association of heat shock protein A2 expression and sperm quality after N-acetyl-cysteine supplementation in astheno-terato-zoospermic infertile men

In infertile men, reduced expression of heat shock protein A2 (HSPA2) is related to reduced sperm quality and function. The present study has aimed to investigate the effects of N-acetyl-cysteine (NAC) supplementation on expression of heat shock protein A2 (HSPA2). In this study in continuation of previous study, semen samples from 50 astheno-terato-zoospermic men who have received NAC (600 mg/day) orally for three months were evaluated for expression HSPA2 using RT-PCR, and Western blot analysis. In addition, semen samples of these individuals were assessed for sperm parameters, DNA fragmentation (TUNEL), protamine deficiency (CMA3), lipid peroxidation index (MDA) and total antioxidant capacity (TCA). All assessment was carried out before and after NAC treatment. In addition to improved sperm parameters and aforementioned functional parameters, the presented results revealed the significant increase in relative expression levels of HSPA2 was obtained after using NAC treatment (p < .05). Correlation analysis also demonstrated that HSPA2 expression is significantly related to most of the assessed parameters. NAC may directly or indecently impose its beneficial effect through increased expression of HSPA2, which plays a potential role in proper folding of element needed to counteract stress condition in infertile individuals.

Distinct expression and localization patterns of HSP70 in developmental reproductive organs of rams

Heat shock protein 70 (HSP70) has been widely reported to play a vital role in maintaining intracellular homeostasis, mainly through cellular protection and immune regulation. The expression and function of HSP70 can vary depending upon species and age. To explore the expression signatures and regulatory functions of HSP70 in the reproductive organs of male sheep, we evaluated the expression and distribution patterns of HSP70 in the testes and epididymides (caput, corpus, and cauda) of Tibetan sheep at three developmental stages (i.e., 3 months, 1 year and 3 years after birth) by qRT-PCR, Western blot and immunofluorescence. HSP70 was found to be expressed in testes, caput, corpus, and cauda epididymides throughout the developmental stages but is mainly expressed postpuberty (1 year and 3 years old). Immunofluorescence results revealed that in the testes, a positive reaction for HSP70 protein was mainly seen in round spermatids and luminal sperms from the groups aged 1 year and 3 years. In caput epididymides, the positive signals for HSP70 protein was notably observed in sperm and principal cells of the epididymal epithelium from the groups aged 1 year and 3 years, and positive signals in the epididymal interstitium were found in all three age groups. In corpus and cauda epididymides, HSP70 protein was present in the epididymal epithelium and interstitium, and the positive signals gradually increased with age. In conclusion, these findings suggest that Tibetan sheep HSP70 may play a crucial role in further development and maturation of postmeiotic germ cells and participate in regulation of intraepididymal homeostasis maintenance in Tibetan sheep.

Melatonin protects the mouse testis against heat-induced damage

Spermatogenesis, an intricate process occurring in the testis, is responsible for ongoing production of spermatozoa and thus the cornerstone of lifelong male fertility. In the testis, spermatogenesis occurs optimally at a temperature 2–4°C lower than that of the core body. Increased scrotal temperature generates testicular heat stress and later causes testicular atrophy and spermatogenic arrest, resulting in a lower sperm yield and therefore impaired male fertility. Melatonin (N-acetyl-5-methoxytryptamine), a small neuro-hormone synthesized and secreted by the pineal gland and the testis, is widely known as a potent free-radical scavenger; it has been reported that melatonin protects the testis against inflammation and reactive oxygen species generation thereby playing anti-inflammatory, -oxidative and -apoptotic roles in the testis. Nevertheless, the role of melatonin in the testicular response to heat stress has not been studied. Here, by employing a mouse model of testicular hyperthermia, we systematically investigated the testicular response to heat stress as well as the occurrence of autophagy, apoptosis and oxidative stress in the testis. Importantly, we found that pre-treatment with melatonin attenuated heat-induced apoptosis and oxidative stress in the testis. Also, post-treatment with melatonin promoted recovery of the testes from heat-induced damage, probably by maintaining the integrity of the Sertoli cell tight-junction. Thus, we for the first time provide the proof of concept that melatonin can protect the testis against heat-induced damage, supporting the potential future use of melatonin as a therapeutic drug in men for sub/infertility incurred by various testicular hyperthermia factors.

Gametogenesis: A journey from inception to conception

Gametogenesis, the process of forming mature germ cells, is an integral part of both an individual's and a species' health and well-being. This chapter focuses on critical male and female genetic and epigenetic processes underlying normal gamete formation through their differentiation to fertilization. Finally, we explore how knowledge gained from this field has contributed to progress in areas with great clinical promise, such as in vitro gametogenesis.

Roles of Figla/figla in Juvenile Ovary Development and Follicle Formation During Zebrafish Gonadogenesis

Sex determination and differentiation are complex processes. As a juvenile hermaphrodite or undifferentiated gonochorist, zebrafish undergo a special juvenile ovarian phase during sex differentiation, making it an excellent model for studying early oogenesis and folliculogenesis. We provide lines of evidence at morphological, molecular, and genetic levels for roles of factor in the germline α (Figla), an oocyte-specific transcription factor, in early zebrafish gonadogenesis. As in mammals, Figla/figla was also expressed in the gonads and its expression in the ovary was also restricted to early oocytes. Disruption of figla gene by CRISPR/Cas9 led to an all-male phenotype in the mutant. Detailed analysis of early gonadal development showed that the germ cells in the mutant were clustered in cysts and underwent meiosis, forming oocytes at prefollicular chromatin nucleolar (CN) stage (stage IA). However, the subsequent transition from cystic CN oocytes to individual follicular perinucleolar oocytes (stage IB) was blocked, resulting in an all-male phenotype in the mutant. The phenotype of figla mutant could not be rescued by estrogen treatment, in contrast to cyp19a1a mutant, and introduction of tp53 mutation also had no effect, unlike in fancd1 and fancl mutants. Transcriptome analysis revealed that many biological processes and pathways related to germ cell development, especially oogenesis, were upregulated in the presence of Figla and that the regulation of figla expression may involve heat shock proteins. Our results strongly suggest important roles for Figla in juvenile ovary development, especially the formation of individual follicles from cystic oocytes.

Germ Cell-Specific Retinoic Acid Receptor α Functions in Germ Cell Organization, Meiotic Integrity, and Spermatogonia

Retinoic acid receptor α (RARA), a retinoic acid-dependent transcription factor, is expressed in both somatic and germ cells of the testis. Rara-null male mice with global Rara mutations displayed severely degenerated testis and infertility phenotypes. To elucidate the specific responsibility of germ cell RARA in spermatogenesis, Rara was deleted in germ cells, generating germ cell-specific Rara conditional knockout (cKO) mice. These Rara cKO animals exhibited phenotypes of quantitatively reduced epididymal sperm counts and disorganized germ cell layers in the seminiferous tubules, which worsened with aging. Abnormal tubules lacked lumen, contained vacuoles, and showed massive germ cell sloughing, all characteristics similar to those observed in Rara-null tubules. Spermatocyte chromosomal spreads revealed a novel role for germ cell RARA in modulating the integrity of synaptonemal complexes and meiotic progression. Furthermore, the initiation of spermatogenesis from spermatogonial stem cells was decreased in Rara cKO testes following busulfan treatment, supporting a role of germ cell RARA in spermatogonial proliferation. Collectively, the evidence in this study indicates that RARA produced in male germ cells has a broad spectrum of functions throughout spermatogenesis, which includes the maintenance of seminiferous epithelium organization, the integrity of the meiotic genome, and spermatogonial proliferation and differentiation. The results further suggest that germ cell RARA has dual functions: intrinsically in germ cells, balancing proliferation and differentiation of spermatogonia, and controlling genome integrity during meiosis; and extrinsically in the crosstalks with Sertoli cells, controlling the cell junctional physiology for coordinating proper spatial and temporal development of germ cells during spermatogenesis.

Characterization of MAGEG2 with testis-specific expression in mice

Male germ cell development is a well-defined process occurring in numerous seminiferous tubules of the testis. Uncovering testicular novel genes related to intrinsic regulation of spermatogenesis is essential for the understanding of spermatogenesis. In the present study, we investigated mouse Mageg2, which belongs to a group of melanoma-associated antigens (MAGEs). Mageg2 is transcribed in the testis specifically, and its expression level is increased at the pachytene spermatocyte stage, indicating that Mageg2 is expressed predominantly in germ cells. We generated an antibody against mouse MAGEG2 for further characterization at the protein level. Immunoblot analysis suggested that MAGEG2 has specific testicular expression and the expression primarily occurred in pachytene spermatocytes. Proteomic analyses demonstrated that mouse MAGEG2 binded to testicular germ cell-specific serine/threonine-protein kinase 31 (STK31) and heat shock protein 9 (HSPA9). Direct binding with both interaction partners was confirmed by co-immunoprecipitation. We found that STK31 and HSPA9 bind MAGEG2 directly but not with each other. Interestingly, MAGEG2 reduced the kinase activity of STK31. Our study suggests that mouse MAGEG2 has at least two functions, including chaperone activity related to HSPA9 and regulation of pachytene spermatocyte-specific kinase, STK31. Altogether, our results provide the first information about MAGEG2 at the transcript and protein levels and suggest its potential molecular functions.

The Expression of TLR2 and TLR3 in Sertoli Cells of Azoospermic Patients

Objective

Toll-like receptors (TLRs) on Sertoli cells are thought to have essential roles in sperm protection. This study was conducted to investigate the expression of TLR2 and TLR3 in Sertoli cells of men with azoospermia.

Materials and Methods

In this experimental study, testicular biopsies were taken from ten azoospermic men. Following enzymatic dissociation, the samples were moved to lectin coated petri dishes. After a few passages, all cells were cultivated and Seroli cells were sorted by flow cytometry. To confirm Sertoli cell purification, alkaline phosphatase activity (ALP) and immunohistochemistry assays were employed. The expression of TLR2 and TLR3 at the transcript and protein levels was examined with real-time quantitative reverse transcription-polymerase chain reaction (RT-QPCR) and western blot, respectively.

Results

Isolation, purification and cultivation of human Sertoli cells were performed successfully. Efficacy of purification of Sertoli cells by fluorescence-activated cell sorting (FACS) sorter was ~97%. The type of cultured cells was confirmed by vimentin and follicle-stimulating hormone (FSH) receptor markers. Furthermore, the existence of anti- Müllerian hormone in culture was confirmed. RT-PCR showed that both genes were expressed in Sertoli cells. Consistently, proteins of both were also expressed in Sertoli cells. Moreover, QPCR showed that the relative expression of TLR3 transcripts was significantly higher than TLR2 in Sertoli cells. Although both genes are expressed in fibroblast cells, their level of expression was significantly lower than in Sertoli cells.

Conclusion

This study confirmed expression of TLR2 and TLR3 in human Sertoli cells. This may be an indicator of their roles in developing immunity against pathogens as well as allo- and auto-antigens or viral antigens in seminiferous tubules.

Heat Shock Protein A2 (HSPA2): Regulatory Roles in Germ Cell Development and Sperm Function

Among the numerous families of heat shock protein (HSP) that have been implicated in the regulation of reproductive system development and function, those belonging to the 70 kDa HSP family have emerged as being indispensable for male fertility. In particular, the testis-enriched heat shock 70 kDa protein 2 (HSPA2) has been shown to be critical for the progression of germ cell differentiation during spermatogenesis in the mouse model. Beyond this developmentally important window, mounting evidence has also implicated HSPA2 in the functional transformation of the human sperm cell during their ascent of the female reproductive tract. Specifically, HSPA2 appears to coordinate the remodelling of specialised sperm domains overlying the anterior region of the sperm head compatible with their principle role in oocyte recognition. The fact that levels of the HSPA2 protein in mature spermatozoa tightly correlate with the efficacy of oocyte binding highlight its utility as a powerful prognostic biomarker of male fertility. In this chapter, we consider the unique structural and biochemical characteristics of HSPA2 that enable this heat shock protein to fulfil its prominent roles in orchestrating the morphological differentiation of male germ cells during spermatogenesis as well as their functional transformation during post-testicular sperm maturation.

Characterization of Mammalian ADAM2 and Its Absence from Human Sperm

The members of the ADAM (a disintegrin and metalloprotease) family are membrane-anchored multi-domain proteins that play prominent roles in male reproduction. ADAM2, which was one of the first identified ADAMs, is the best studied ADAM in reproduction. In the male germ cells of mice, ADAM2 and other ADAMs form complexes that contribute to sperm-sperm adhesion, sperm-egg interactions, and the migration of sperm in the female reproductive tract. Here, we generated specific antibodies against mouse and human ADAM2, and investigated various features of ADAM2 in mice, monkeys and humans. We found that the cytoplasmic domain of ADAM2 might enable the differential association of this protein with other ADAMs in mice. Western blot analysis with the anti-human ADAM2 antibodies showed that ADAM2 is present in the testis and sperm of monkeys. Monkey ADAM2 was found to associate with chaperone proteins in testis. In humans, we identified ADAM2 as a 100-kDa protein in the testis, but failed to detect it in sperm. This is surprising given the results in mice and monkeys, but it is consistent with the failure of ADAM2 identification in the previous proteomic analyses of human sperm. These findings suggest that the reproductive functions of ADAM2 differ between humans and mice. Our protein analysis showed the presence of potential ADAM2 complexes involving yet-unknown proteins in human testis. Taken together, our results provide new information regarding the characteristics of ADAM2 in mammalian species, including humans.

Characterization of Mammalian ADAM2 and Its Absence from Human Sperm

The members of the ADAM (a disintegrin and metalloprotease) family are membrane-anchored multi-domain proteins that play prominent roles in male reproduction. ADAM2, which was one of the first identified ADAMs, is the best studied ADAM in reproduction. In the male germ cells of mice, ADAM2 and other ADAMs form complexes that contribute to sperm-sperm adhesion, sperm-egg interactions, and the migration of sperm in the female reproductive tract. Here, we generated specific antibodies against mouse and human ADAM2, and investigated various features of ADAM2 in mice, monkeys and humans. We found that the cytoplasmic domain of ADAM2 might enable the differential association of this protein with other ADAMs in mice. Western blot analysis with the anti-human ADAM2 antibodies showed that ADAM2 is present in the testis and sperm of monkeys. Monkey ADAM2 was found to associate with chaperone proteins in testis. In humans, we identified ADAM2 as a 100-kDa protein in the testis, but failed to detect it in sperm. This is surprising given the results in mice and monkeys, but it is consistent with the failure of ADAM2 identification in the previous proteomic analyses of human sperm. These findings suggest that the reproductive functions of ADAM2 differ between humans and mice. Our protein analysis showed the presence of potential ADAM2 complexes involving yet-unknown proteins in human testis. Taken together, our results provide new information regarding the characteristics of ADAM2 in mammalian species, including humans.

Retinoic Acid Is Sufficient for the In Vitro Induction of Mouse Spermatocytes

Meiosis is the key step in gametogenesis. However, the mechanism of mammalian meiosis remains poorly understood due to the lack of an in vitro model. Here, we report that retinoic acid (RA) is sufficient for inducing leptotene/zygotene spermatocytes from cultured mouse spermatogonial stem cells. Multiple genes regulated by RA were identified by RNA sequencing. RA in combination with pup Sertoli cell co-culture resulted in a higher induction efficiency of 28%. Comparisons in the transcriptomic profiles of the induced spermatogenic cells and the isolated ones revealed the progressive induction of the germ cells. Using this model, we showed that Stra8, Agpat3, Fam57a, Wdr91, and Sox30 contributed to the proliferation and meiosis initiation differentially. In conclusion, we have efficiently generated spermatocytes using an RA/pup Sertoli cell-based in vitro model and provided proof-of-concept evidence for its application in identifying genes involved in mammalian meiosis.

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Retinoic acid (RA) is sufficient for the induction of spermatocytes

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RA activates meiotic genes while repressing genes for SSC self-renewal

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An in vitro model for meiosis based on RA and pup Sertoli cells is established

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Genes for meiosis have been identified using the in vitro model

In vitro effects of date palm (Phoenix dactylifera L.) pollen on colonization of neonate mouse spermatogonial stem cells

ETHNOPHARMACOLOGICAL RELEVANCE

Date palm (Phoenix dactylifera L.) pollen (DPP) is widely used as a folk remedy for male infertility treatment, and has well known medicinal effects.

AIM OF THE STUDY

This study aimed to determine the in vitro effects of DPP on the efficiency of neonate mouse spermatogonial stem cells (SSCs) proliferation.

MATERIAL AND METHODS

Sertoli and SSCs were isolated from 6 to 10-days-old mouse testes, and their identity was confirmed using immunocytochemistry against cytokeratin for sertoli cells and PLZF, Oct-4 and CDH-1 for SSCs. Isolated testicular cells were cultured in the absence or presence of 0.06, 0.25 and 0.62mg/ml concentrations of DPP aqueous extract for 2 weeks. The number and diameter of SSC colonies were assessed during third, 7th, 9th and 14th day of culture, and the expression of the Mvh, GFRα-1 and Oct-4 was evaluated using quantitative PCR at the end of the culture period. The significance of the data was analyzed using ANOVA and paired samples t-test and Tukey and Bonferroni test as post hoc tests at the level of p≤0.05.

RESULTS

Pattern assay of colony formation showed that SSCs numbers increased in the present of 0.62mg/ml concentration of DPP extract with higher slop relative to other groups (P <0.05). Colony diameters had no significant difference between groups in 3th, 7th, 9th and 14th days after culture. The Mvh and Oct-4 genes expression had no significant difference between groups, while GFRα1 expression was increased significantly in cells treated with 0.06mg/ml concentration relative to other groups (P<0.05).

CONCLUSION

It seems that co-culture of SSCs with sertoli sells in the presence of low doses of DPP can increase SSCs proliferation and keep their stemness state, while higher concentrations can differentiate the treated cells.

The role of the molecular chaperone heat shock protein A2 (HSPA2) in regulating human sperm-egg recognition

One of the most common lesions present in the spermatozoa of human infertility patients is an idiopathic failure of sperm-egg recognition. Although this unique cellular interaction can now be readily by-passed by assisted reproductive strategies such as intracytoplasmic sperm injection (ICSI), recent large-scale epidemiological studies have encouraged the cautious use of this technology and highlighted the need for further research into the mechanisms responsible for defective sperm-egg recognition. Previous work in this field has established that the sperm domains responsible for oocyte interaction are formed during spermatogenesis prior to being dynamically modified during epididymal maturation and capacitation in female reproductive tract. While the factors responsible for the regulation of these sequential maturational events are undoubtedly complex, emerging research has identified the molecular chaperone, heat shock protein A2 (HSPA2), as a key regulator of these events in human spermatozoa. HSPA2 is a testis-enriched member of the 70 kDa heat shock protein family that promotes the folding, transport, and assembly of protein complexes and has been positively correlated with in vitro fertilization (IVF) success. Furthermore, reduced expression of HSPA2 from the human sperm proteome leads to an impaired capacity for cumulus matrix dispersal, sperm-egg recognition and fertilization following both IVF and ICSI. In this review, we consider the evidence supporting the role of HSPA2 in sperm function and explore the potential mechanisms by which it is depleted in the spermatozoa of infertile patients. Such information offers novel insights into the molecular mechanisms governing sperm function.

Malfunction of spermatogenesis in experimental ischemic mice

An experimental ischemia (EI)-induced mouse model was used to analyze pathological and biochemical alterations in testes. Initial morphological changes were observed in Sertoli cells of EI testes at the light microscopic level. Examination of the ultrastructure using transmission electron microscopy confirmed that Sertoli cells were partially detached from the basement membrane of the seminiferous epithelium and that the cell membranes of adjacent Sertoli cells were not joined. The functional integrity of the blood-testis barrier (BTB) was assessed using the lanthanum tracer technique. Lanthanum had penetrated into the spaces between adjacent Sertoli cells in the adluminal compartment up to the lumen of the seminiferous epithelium in EI testes. Proteome analysis showed that the expression of heat shock protein (HSP) 70 was significantly upregulated in EI testes. Western blot analysis confirmed that the expression of HSP70 increased in a time-dependent manner after the EI procedure. HSP70 immunostaining was observed in spermatocytes and in round and elongated spermatids in EI testes. Our results suggest that a change in the junctions between adjacent Sertoli cells on the basal compartment is involved in the BTB disruption in EI testes. Therefore, male infertility caused by the BTB disruption could be associated with heat stress induced by ischemia.

Mammalian gonocyte and spermatogonia differentiation: recent advances and remaining challenges

The production of spermatozoa relies on a pool of spermatogonial stem cells (SSCs), formed in infancy from the differentiation of their precursor cells, the gonocytes. Throughout adult life, SSCs will either self-renew or differentiate, in order to maintain a stem cell reserve while providing cells to the spermatogenic cycle. By contrast, gonocytes represent a transient and finite phase of development leading to the formation of SSCs or spermatogonia of the first spermatogenic wave. Gonocyte development involves phases of quiescence, cell proliferation, migration, and differentiation. Spermatogonia, on the other hand, remain located at the basement membrane of the seminiferous tubules throughout their successive phases of proliferation and differentiation. Apoptosis is an integral part of both developmental phases, allowing for the removal of defective cells and the maintenance of proper germ–Sertoli cell ratios. While gonocytes and spermatogonia mitosis are regulated by distinct factors, they both undergo differentiation in response to retinoic acid. In contrast to postpubertal spermatogenesis, the early steps of germ cell development have only recently attracted attention, unveiling genes and pathways regulating SSC self-renewal and proliferation. Yet, less is known on the mechanisms regulating differentiation. The processes leading from gonocytes to spermatogonia have been seldom investigated. While the formation of abnormal gonocytes or SSCs could lead to infertility, defective gonocyte differentiation might be at the origin of testicular germ cell tumors. Thus, it is important to better understand the molecular mechanisms regulating these processes. This review summarizes and compares the present knowledge on the mechanisms regulating mammalian gonocyte and spermatogonial differentiation.

Effect of different doses of nandrolone decanoate on lipid peroxidation, DNA fragmentation, sperm abnormality and histopathology of testes of male Wister rats

The present study aims of to investigate the effects of low and high doses of nandrolone decanoate (ND) on histopathology and apoptosis of the spermatogenic cells as well as lipid peroxidation, antioxidant enzyme activities, sperm abnormality and DNA fragmentation. Eighteen animals were divided into three groups each group contain six animals. The rats were divided into three groups as following: Group 1 was administered saline (control). Group 2, received nandrolone decanoate (3 mg/kg/weekly) (low dose) with intramuscular injection. Group 3, received intramuscular injection dose of nandrolone decanoate (10 mg/kg/weekly) (high dose). After 8 weeks, caspase-3 assay was used to determine the apoptotic cells. The sperm parameters, lipid peroxidation, antioxidant enzyme activities and testosterone concentration were also investigated in the experimental groups of both low and high dose compared to the control groups. Treated group with high dose showed degenerated germinal epithelial cells sloughed in the lumina of seminiferous tubules, where almost seminiferous tubules were devoid of spermatids and spermatozoa compared to control and group treated with low dose. Also, a significant increase of lipid peroxidation levels and heat shock proteins was observed in two groups administrated with two different doses of ND while, antioxidant enzyme activities, and testosterone concentration was significantly decreased in two treated group when compared with control. Administration of ND at high and low doses leads to deteriorated sperm parameters, DNA fragmentation and testicular apoptosis. In conclusion, the administration ND at high doses more effective on lipid peroxidation, antioxidant enzyme activities, sperm abnormality, histopathology, apoptotic and DNA changes compared to low dose group and to control group.

Retinoic acid induces multiple hallmarks of the prospermatogonia-to-spermatogonia transition in the neonatal mouse

In mammals, most neonatal male germ cells (prospermatogonia) are quiescent and located in the center of the testis cords. In response to an unknown signal, prospermatogonia transition into spermatogonia, reenter the cell cycle, divide, and move to the periphery of the testis cords. In mice, these events occur by 3-4 days postpartum (dpp), which temporally coincides with the onset of retinoic acid (RA) signaling in the neonatal testis. RA has a pivotal role in initiating germ cell entry into meiosis in both sexes, yet little is known about the mechanisms and about cellular changes downstream of RA signaling. We examined the role of RA in mediating the prospermatogonia-to-spermatogonia transition in vivo and found 24 h of precocious RA exposure-induced germ cell changes mimicking those that occur during the endogenous transition at 3-4 dpp. These changes included: 1) spermatogonia proliferation; 2) maturation of cellular organelles; and 3), expression of markers characteristic of differentiating spermatogonia. We found that germ cell exposure to RA did not lead to cellular loss from apoptosis but rather resulted in a delay of ∼2 days in their entry into meiosis. Taken together, our results indicate that exogenous RA induces multiple hallmarks of the transition of prospermatogonia to spermatogonia prior to their entry into meiosis.

Optimized flow cytometry isolation of murine spermatocytes

Meiotic prophase I (MPI), is an initial stage of meiosis characterized by intricate homologous chromosome interactions, synapsis, and DNA recombination. These processes depend on the complex, but poorly understood early MPI events of homologous chromosome search, alignment, and pairing. Detailed molecular investigation of these early events requires isolation of individual MPI substages. Enrichment for Pachytene (P) and Diplotene (D) substages of late MPI was previously accomplished using flow cytometry. However, separation of early MPI spermatocytes, specifically, of Leptotene (L) and Zygotene (Z) substages, has been a challenge due to these cells' similar characteristics. In this report, we describe an optimized Hoechst-33342 (Hoechst)-based flow cytometry approach for isolating individual MPI populations from adult mouse testis. We get significant enrichment for individual L and Z spermatocytes, previously inseparable from each other, and optimize the isolation of other MPI substages. Our flow cytometry approach is a combination of three optimized strategies. The first is optimization of testis dissociation protocol that yields more consistent and reproducible testicular single cell suspension. The second involves optimization of flow cytometric gating protocol where a critical addition to the standard protocol for cell discrimination based on Hoechst fluorescence, involves a back-gating technique based on light scattering parameters. This step specifies selection of individual MPI substages. The third, is an addition of DNA content restriction to the gating protocol to minimize contamination from non-meiotic cells. Finally, we confirm significant enrichment of high-purity Preleptotene (PreL), L, Z, P, and D MPI spermatocytes using stage-specific marker distribution. The technique will facilitate understanding of the molecular events underlying MPI.

The paternal age effect: a multifaceted phenomenon

Birth rates for older fathers have increased 30% since 1980. When combined with the increased risk for genetic and multifactorial disorders in children conceived by older fathers, paternal age has become an important health issue for modern society. Laboratory research in this area has been minimal, perhaps because of significant experimental barriers, not the least of which is inadequate access to fresh, disease-free human testicular tissue. Regardless, progress has been made and intriguing models supported by experimental evidence have been proposed. The putative mechanisms range from reduced DNA repair activity, leading to increased mutagenesis, to positive selection of germ cells harboring specific disease-causing mutations. There remain many important venues for research in this increasingly relevant phenomenon that impacts future generations.

Is thioredoxin reductase involved in the defense against DNA fragmentation in varicocele?

We aimed to investigate the role of thioredoxin reductase (TR) and inducible heat shock protein 70 (iHsp70) and their relationship with sperm quality in varicocele (VAR) patients. Semen samples were obtained from 16 subfertile men diagnosed as VAR and 10 fertile men who applied to the Andrology Laboratory of Istanbul Medical Faculty of Istanbul University. The sperm TR and iHsp 70 expression levels were determined using Western blot analysis. The TR activity of the sperm was assayed spectrophometrically. The sperm quality was evaluated both by conventional sperm analysis and by a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) technique that assayed DNA-fragmented spermatozoa in semen samples. The percentage of TUNEL-positive spermatozoa in the VAR group (16.3%± 5.6%) was higher than that in the fertile group (5.5%± 1.9%). Significant inverse correlations were detected between the percentage of TUNEL-positive cells and both the concentration (r=-0.609; P=0.001) and motility (r=-0.550; P=0.004) of spermatozoa. Both the TR expression and activity were increased significantly in the VAR group (U=22.0; P=0.001 and U=33.5; P=0.012, respectively) as analyzed using the Mann-Whitney U Wilcoxon rank sum W test. Furthermore, significant positive correlations were found between TR expression and activity (r=0.406; P=0.040) and between TR expression and the percentage of TUNEL-positive cells (r=0.665; P=0.001). Sperm iHsp70 expression did not differ between the VAR and fertile groups. In conclusion, increased sperm TR expression might be a defense mechanism against apoptosis in the spermatozoa of men with VAR.

The function of chaperone proteins in the assemblage of protein complexes involved in gamete adhesion and fusion processes

The remarkable complexity of the molecular events governing adhesion and fusion of the male and female gametes is becoming apparent. Novel research suggests that these highly specific cellular interactions are facilitated by multiprotein complexes that are delivered to and/or assembled on the surface of the gametes by molecular chaperones in preparation for sperm-egg interaction. While the activation of these molecular chaperones and the mechanisms by which they shuttle proteins to the surface of the cell remain the subject of ongoing investigation, a compelling suggestion is that these processes are augmented by dynamic membrane microdomains or lipid rafts that migrate to the apical region of the sperm head after capacitation. Preliminary studies of the oocyte plasma membrane have also revealed the presence of lipid rafts comprising several molecular chaperones, raising the possibility that similar mechanisms may be involved in the activation of maternal fusion machinery and the regulation of oocyte plasma membrane integrity. Despite these findings, the analysis of oocyte surface multiprotein complexes is currently lacking. Further analyses of the intermediary proteins that facilitate the expression of key players in sperm-egg fusion are likely to deliver important insights into this unique event, which culminates in the cytoplasmic continuity of the male and female gametes.

The molecular chaperone HSPA2 plays a key role in regulating the expression of sperm surface receptors that mediate sperm-egg recognition

A common defect encountered in the spermatozoa of male infertility patients is an idiopathic failure of sperm–egg recognition. In order to resolve the molecular basis of this condition we have compared the proteomic profiles of spermatozoa exhibiting an impaired capacity for sperm-egg recognition with normal cells using label free mass spectrometry (MS)-based quantification. This analysis indicated that impaired sperm–zona binding was associated with reduced expression of the molecular chaperone, heat shock 70 kDa protein 2 (HSPA2), from the sperm proteome. Western blot analysis confirmed this observation in independent patients and demonstrated that the defect did not extend to other members of the HSP70 family. HSPA2 was present in the acrosomal domain of human spermatozoa as a major component of 5 large molecular mass complexes, the most dominant of which was found to contain HSPA2 in close association with just two other proteins, sperm adhesion molecule 1 (SPAM1) and arylsulfatase A (ARSA), both of which that have previously been implicated in sperm-egg interaction. The interaction between SPAM1, ARSA and HSPA2 in a multimeric complex mediating sperm-egg interaction, coupled with the complete failure of this process when HSPA2 is depleted in infertile patients, provides new insights into the mechanisms by which sperm function is impaired in cases of male infertility.

In vitro culture and morphological characterization of prepubertal buffalo (Bubalus bubalis) putative spermatogonial stem cell

PURPOSE

Spermatogonial stem cells (SSCs) have the unique ability both to self-renew and to produce progeny that undergo differentiation to spermatozoa. The present study has been carried out to develop a method to purify and enrich the pure populations of spermatogonial stem cell like cells in buffalo.

METHODS

The spermatogonial cells were isolated from testes of 3-7 month old buffalo calves and disaggregated by double enzymatic digestion. Mixed population of isolated cells were then plated on Datura stramonium agglutinin (DSA) lectin coated dishes for attachment of Sertoli cells. The desired cells were obtained from suspension medium after 18 h of incubation and then loaded on discontinuous density gradient using percoll (20-65 %) and different types of spermatogonia cells were obtained at interface of each layer. These cells were cultured in vitro.

RESULTS

Spermatogonial cells isolated have spherical outline and two or three eccentrically placed nucleoli, created a colony after proliferation during first week or immediately after passage. After 7-10 days of culture, the resulted developed colonies of spermatogonial cells expressed the spermatogonial specific genes like Plzf and VASA; and other pluripotency related markers viz. alkaline phosphtase, DBA, CD9, CD90, SSEA-1, OCT-4, NANOG and REX-1.

CONCLUSION

Our results show that the isolated putative spermatogonial stem cells exhibit the expression of pluripotency related and spermatogonial specific genes. This study may help to establish a long term culture system for buffalo spermatogonia.

Proteomic changes in rat spermatogenesis in response to in vivo androgen manipulation; impact on meiotic cells

The production of mature sperm is reliant on androgen action within the testis, and it is well established that androgens act on receptors within the somatic Sertoli cells to stimulate male germ cell development. Mice lacking Sertoli cell androgen receptors (AR) show late meiotic germ cell arrest, suggesting Sertoli cells transduce the androgenic stimulus co-ordinating this essential step in spermatogenesis. This study aimed to identify germ cell proteins responsive to changes in testicular androgen levels and thereby elucidate mechanisms by which androgens regulate meiosis. Testicular androgen levels were suppressed for 9 weeks using testosterone and estradiol-filled silastic implants, followed by a short period of either further androgen suppression (via an AR antagonist) or the restoration of intratesticular testosterone levels. Comparative proteomics were performed on protein extracts from enriched meiotic cell preparations from adult rats undergoing androgen deprivation and replacement in vivo. Loss of androgenic stimulus caused changes in proteins with known roles in meiosis (including Nasp and Hsp70–2), apoptosis (including Diablo), cell signalling (including 14-3-3 isoforms), oxidative stress, DNA repair, and RNA processing. Immunostaining for oxidised DNA adducts confirmed spermatocytes undergo oxidative stress-induced DNA damage during androgen suppression. An increase in PCNA and an associated ubiquitin-conjugating enzyme (Ubc13) suggested a role for PCNA-mediated regulation of DNA repair pathways in spermatocytes. Changes in cytoplasmic SUMO1 localisation in spermatocytes were paralleled by changes in the levels of free SUMO1 and of a subunit of its activating complex, suggesting sumoylation in spermatocytes is modified by androgen action on Sertoli cells. We conclude that Sertoli cells, in response to androgens, modulate protein translation and post-translational events in spermatocytes that impact on their metabolism, survival, and completion of meiosis.

Evaluation of the effects of cryopreservation on viability, proliferation and colony formation of human spermatogonial stem cells in vitro culture

Proliferation of spermatogonial stem cells (SSCs) in vitro system is very important. It can enhance SSCs numbers for success of transplantation and treatment of infertility in cancer patients. In this study, testicular cells that obtained from azoospermia patients (n=8) by enzymatic digestion were cryopreserved at the beginning and after 2 weeks of culture. Then, frozen-thawed SSCs were co-cultured on fresh Sertoli cells (experimental group 1), and frozen-thawed Sertoli cells (experimental group 2) for another 3 weeks. In control group, fresh SSCs were co-cultured on fresh Sertoli cells. Viability rate after enzymatic digestion was 93.4%±5.0. Frozen-thawed testicular cells after 2 weeks of culture had a significantly (P<0.05) higher percentage of living cells compared to frozen-thawed testicular cells at the beginning of culture (59.2±7.05 and 46.3±8.40 respectively). The number of colonies in the experimental group 1 was significantly higher than experimental group 2 (19.6±2.8 and 8.33±1.5, respectively, P<0.05). The diameter of the colonies in the experimental group 1 was significantly higher than control and experimental group 2 (P<0.05) after 3 weeks of culture (269.7±52.1, 204.34±24.1 and 112.52±23.5 μm, respectively). Cryopreservation technique will raise the possibility of banking SSCs for men who have a cancer-related illness and waiting for radiotherapy and/or chemotherapy.

Characterization of heat shock protein 70 in the red claw crayfish (Cherax quadricarinatus): evidence for its role in regulating spermatogenesis

Heat shock protein 70 (HSP70) is a member of molecular chaperones and is important for reproductive biological processes in eukaryotes. In this regard, a full length HSP70 comprised of 2366 nucleotides from the red claw crayfish Cherax quadricarinatus (CqHSP70) was characterized, which with an open-reading frame of 1959 bp encoded 652 amino acid residues. Its mRNA transcript expression in the testes was measured by real-time quantitative PCR. CqHSP70 mRNA transcripts were detected in all organs especially high in the testes. Furthermore, the greatest transcript levels were found during the spermatogonial preparation phase, while the lowest levels were found during the resting stage of the reproductive cycle. In addition, its distribution in the testes was determined by Western blot and immunohistochemistry. Western blot results revealed a single immunoreactive band with an estimated molecular mass of 70 kDa in different phases of testes development. The strongest immunolabeling positive signal was found in spermatogonia, with lower positive staining in secondary spermatocytes, and weak or absent level in the mature sperm. Interestingly, CqHSP70 was mainly located in the cytoplasm of sperm cells. Thus, our results indicate that CqHSP70 is an essential protein in spermatogenesis, with a crucial reproductive function during sperm maturation in invertebrates.

Male hypogonadism and germ cell loss caused by a mutation in Polo-like kinase 4

The genetic etiologies of male infertility remain largely unknown. To identify genes potentially involved in spermatogenesis and male infertility, we performed genome-wide mutagenesis in mice with N-ethyl-N-nitrosourea and identified a line with dominant hypogonadism and patchy germ cell loss. Genomic mapping and DNA sequence analysis identified a novel heterozygous missense mutation in the kinase domain of Polo-like kinase 4 (Plk4), altering an isoleucine to asparagine at residue 242 (I242N). Genetic complementation studies using a gene trap line with disruption in the Plk4 locus confirmed that the putative Plk4 missense mutation was causative. Plk4 is known to be involved in centriole formation and cell cycle progression. However, a specific role in mammalian spermatogenesis has not been examined. PLK4 was highly expressed in the testes both pre- and postnatally. In the adult, PLK4 expression was first detected in stage VIII pachytene spermatocytes and was present through step 16 elongated spermatids. Because the homozygous Plk4(I242N/I242N) mutation was embryonic lethal, all analyses were performed using the heterozygous Plk4(+/I242N) mice. Testis size was reduced by 17%, and histology revealed discrete regions of germ cell loss, leaving only Sertoli cells in these defective tubules. Testis cord formation (embryonic day 13.5) was normal. Testis histology was also normal at postnatal day (P)1, but germ cell loss was detected at P10 and subsequent ages. We conclude that the I242N heterozygous mutation in PLK4 is causative for patchy germ cell loss beginning at P10, suggesting a role for PLK4 during the initiation of spermatogenesis.

Induction and persistence of abnormal testicular germ cells following gestational exposure to di-(n-butyl) phthalate in p53-null mice

Phthalate esters are commonly used plasticizers found in many household items, personal care products, and medical devices. Animal studies have shown that in utero exposure to di-(n-butyl) phthalate (DBP) within a critical window during gestation causes male reproductive tract abnormalities resembling testicular dysgenesis syndrome. Our studies utilized p53-deficient mice for their ability to display greater resistance to apoptosis during development. This model was chosen to determine whether multinucleated germ cells (MNG) induced by gestational DBP exposure could survive postnatally and evolve into testicular germ cell cancer. Pregnant dams were exposed to DBP (500 mg/kg/day) by oral gavage from gestational day 12 until birth. Perinatal effects were assessed on gestational day 19 and postnatal days 1, 4, 7, and 10 for the number of MNGs present in control and DBP-treated p53-heterozygous and null animals. As expected, DBP exposure induced MNGs, with greater numbers found in p53-null mice. Additionally, there was a time-dependent decrease in the incidence of MNGs during the early postnatal period. Histologic examination of adult mice exposed in utero to DBP revealed persistence of abnormal germ cells only in DBP-treated p53-null mice, not in p53-heterozygous or wild-type mice. Immunohistochemical staining of perinatal MNGs and adult abnormal germ cells was negative for both octamer-binding protein 3/4 and placental alkaline phosphatase. This unique model identified a role for p53 in the perinatal apoptosis of DBP-induced MNGs and provided insight into the long-term effects of gestational DBP exposure within a p53-null environment.

Comparison of colony formation in adult mouse spermatogonial stem cells developed in Sertoli and STO coculture systems

This study aimed to compare the in vitro effects of coculture with Sertoli and SIM mouse embryo-derived thioguanine- and ouabain-resistant (STO) feeder layer cells on the efficiency of adult mouse spermatogonial stem cells (SSCs) colony formation. Sertoli and SSCs were isolated from testes, and their identity was confirmed using immunocytochemistry against Oct4, CDH1, PLZF and C-kit for SSCs and vimentin for Sertoli cells. SSCs were cultured in a simple culture system (control group) and on top of the Sertoli and STO feeder layers for 2 weeks. The number and diameter of colonies were evaluated during third, 7th, 10th and 14th day of culture, and the expression of the Oct-4, α6 and β1 integrins was assessed using quantitative RT-PCR. Significant differences were observed between the three groups, separately for each time (P < 0.05), with higher mean in number and diameter for Sertoli cells (P < 0.05). The results of RT-PCR showed higher gene expression of β1 integrin in Sertoli group, but no significant differences were observed in Oct-4 and α6 integrin gene expression among the three groups. Based the on the optimal effect of Seroli cells on the colony formation of SSCs, it is suggested to use these cells for better colonisation of SSCs.

BCL2 Ala43Thr is a functional variant associated with protection against azoospermia in a Han-Chinese population

Apoptosis is very common during various stages of mammalian germ cell development and differentiation, and the BCL2 gene is one of the most important apoptotic regulators. Although its genetic variants are reported to be involved in cancers and autoimmune diseases, little information is available regarding BCL2 polymorphisms in male spermatogenesis. In the present study, single nucleotide polymorphisms (SNPs) in coding regions of the BCL2 gene were examined in a hospital-based, case-control study including 198 infertile patients with idiopathic azoospermia and 183 fertile controls. Subsequently, a functional study was conducted for comparison of paclitaxel-induced cytotoxicity and apoptosis between the BCL2 variant and the wild type in vitro. Three SNPs were found in exon 2--A21G (rs1801018), G127A (rs1800477), and C300T (rs61733416)--with the latter first reported in the Han-Chinese population. The frequency of G127A (GA+AA) genotype was significantly lower in azoospermic, infertile men compared to the age-matched controls (P = 0.01). This genotype may confer a lower risk of azoospermia (adjusted odd ratio [OR] = 0.448, 95% confidence interval = 0.226-0.889). In addition, HeLa cells expressing the BCL2 Ala43Thr (G127A), similar to the control cells, were more sensitive to paclitaxel-induced cytotoxicity and apoptosis than those expressing wild-type BCL2. Consistently, the cleaved PARP and p-BCL2 proteins were subsequently increased after paclitaxel treatment, as also predicted by the bioinformatics analysis. Considering the decreased antiapoptotic function of BCL2, these results suggest that the Ala43Thr variant is associated with protection against azoospermia in the Han-Chinese population.

The endocytic recycling regulator EHD1 is essential for spermatogenesis and male fertility in mice

Background

The C-terminal Eps15 homology domain-containing protein 1 (EHD1) is ubiquitously expressed and regulates the endocytic trafficking and recycling of membrane components and several transmembrane receptors. To elucidate the function of EHD1 in mammalian development, we generated Ehd1^-/- mice using a Cre/loxP system.

Results

Both male and female Ehd1^-/- mice survived at sub-Mendelian ratios. A proportion of Ehd1^-/- mice were viable and showed smaller size at birth, which continued into adulthood. Ehd1^-/- adult males were infertile and displayed decreased testis size, whereas Ehd1^-/- females were fertile. In situ hybridization and immunohistochemistry of developing wildtype mouse testes revealed EHD1 expression in most cells of the seminiferous epithelia. Histopathology revealed abnormal spermatogenesis in the seminiferous tubules and the absence of mature spermatozoa in the epididymides of Ehd1^-/- males. Seminiferous tubules showed disruption of the normal spermatogenic cycle with abnormal acrosomal development on round spermatids, clumping of acrosomes, misaligned spermatids and the absence of normal elongated spermatids in Ehd1^-/- males. Light and electron microscopy analyses indicated that elongated spermatids were abnormally phagocytosed by Sertoli cells in Ehd1^-/- mice.

Conclusions

Contrary to a previous report, these results demonstrate an important role for EHD1 in pre- and post-natal development with a specific role in spermatogenesis.

Biological species is the only possible form of existence for higher organisms: the evolutionary meaning of sexual reproduction

Consistent holistic view of sexual species as the highest form of biological existence is presented. The Weismann's idea that sex and recombination provide the variation for the natural selection to act upon is dominated in most discussions of the biological meaning of the sexual reproduction. Here, the idea is substantiated that the main advantage of sex is the opposite: the ability to counteract not only extinction but further evolution as well. Living systems live long owing to their ability to reproduce themselves with a high fidelity. Simple organisms (like bacteria) reach the continued existence due to the high fidelity of individual genome replication. In organisms with a large genome and complex development, the achievable fidelity of DNA replication is not enough for the precise reproduction of the genome. Such species must be capable of surviving and must remain unchanged in spite of the continuous changes of their genes. This problem has no solution in the frame of asexual ("homeogenomic") lineages. They would rapidly degrade and become extinct or blurred out in the course of the reckless evolution. The core outcome of the transition to sexual reproduction was the creation of multiorganismic entity - biological species. Individual organisms forfeited their ability to reproduce autonomously. It implies that individual organisms forfeited their ability to substantive evolution. They evolve as a part of the biological species. In case of obligatory sexuality, there is no such a thing as synchronic multi-level selection. Natural selection cannot select anything that is not a unit of reproduction. Hierarchy in biology implies the functional predestination of the parts for the sake of the whole. A crucial feature of the sexual reproduction is the formation of genomes of individual organisms by random picking them over from the continuously shuffled gene pool instead of the direct replication of the ancestor's genome. A clear anti-evolutionary consequence of the sexuality is evident from the fact that the genotypes of the individuals with an enhanced competitiveness are not transmitted to the next generation. Instead, after mating with "ordinary" individuals, these genotypes scatter and rearrange in new gene combinations, thus preventing the winner from exploiting the success.

GC-1 mRHBDD1 knockdown spermatogonia cells lose their spermatogenic capacity in mouse seminiferous tubules

Background

Apoptosis is important for regulating spermatogenesis. The protein mRHBDD1 (mouse homolog of human RHBDD1)/rRHBDD1 (rat homolog of human RHBDD1) is highly expressed in the testis and is involved in apoptosis of spermatogonia. GC-1, a spermatogonia cell line, has the capacity to differentiate into spermatids within the seminiferous tubules. We constructed mRHBDD1 knockdown GC-1 cells and evaluated their capacity to differentiate into spermatids in mouse seminiferous tubules.

Results

Stable mRHBDD1 knockdown GC-1 cells were sensitive to apoptotic stimuli, PS341 and UV irradiation. In vitro, they survived and proliferated normally. However, they lost the ability to survive and differentiate in mouse seminiferous tubules.

Conclusion

Our findings suggest that mRHBDD1 may be associated with mammalian spermatogenesis.

Apoptosis induced by acrylamide is suppressed in a 21.5% fat diet through caspase-3-independent pathway in mice testis

This study investigates the simultaneous effect of acrylamide (ACR) and high-fat-intake on the apoptosis in testis cells, and also the expression and activity of caspase-3. Seventy-two male Kunming mice were divided into two blocks and fed with a high-fat diet (crude fat 21.5%) or basic diet (crude fat 4.4%), respectively; and animals in each diet block were exposed to ACR at the dose of 20 mg/kgbw x d or 40 mg/kgbw x d as ACR treated groups or the normal saline as control. Germ cells prepared from testis were stained with Hoechst dye 33258 and paraffin wax sections from testis were suffered to a TUNEL process. Expression of caspase-3 on protein level was investigated using an immunohistochemical analysis assay. The supernatant of unilateral testes were subjected to a Caspase-3 activity kit to determine the activity of Caspase-3 in testis. The concentration of ACR and glycidamide(GA), epoxide of ACR, in plasma and testis were detected by LC-ES/MS/MS analysis. Results based on the morphological changes, percentage of apoptotic cells, and integrated optical density (IOD) of positive amethyst staining which indicates the apoptotic DNA fragmentation, show that apoptosis was induced by acrylamide only; however, acrylamide-induced apoptosis was weakened by high-fat-intake. The protein expression and activity of Caspase-3 were not induced by ACR or high-fat-intake. Moreover, no significant differences of ACR and GA concentration were found between the high-fat and basic diet groups after exposure of ACR. Results indicate that high-fat-intake reverses the effects on apoptosis induced by ACR; and more possibly, apoptosis is induced by a caspase-3-independent mechanism.

Chaperones in cell cycle regulation and mitogenic signal transduction: a review

Chaperones/heat shock proteins (HSPs) of the HSP90 and HSP70 families show elevated levels in proliferating mammalian cells and a cell cycle-dependent expression. They transiently associate with key molecules of the cell cycle control system such as Cdk4, Wee-1, pRb, p53, p27/Kip1 and are involved in the nuclear localization of regulatory proteins. They also associate with viral oncoproteins such as SV40 super T, large T and small t antigen, polyoma large and middle S antigen and EpsteinBarr virus nuclear antigen. This association is based on a J-domain in the viral proteins and may assist their targeting to the pRb/E2F complex. Small HSPs and their state of phosphorylation and oligomerization also seem to be involved in proliferation and differentiation. Chaperones/HSPs thus play important roles within cell cycle processes. Their exact functioning, however, is still a matter of discussion. HSP90 in particular, but also HSP70 and other chaperones associate with proteins of the mitogen-activated signal cascade, particularly with the Src kinase, with tyrosine receptor kinases, with Raf and the MAP-kinase activating kinase (MEK). This apparently serves the folding and translocation of these proteins, but possibly also the formation of large immobilized complexes of signal transducing molecules (scaffolding function).

Mutagenesis is elevated in male germ cells obtained from DNA polymerase-beta heterozygous mice

Gametes carry the DNA that will direct the development of the next generation. By compromising genetic integrity, DNA damage and mutagenesis threaten the ability of gametes to fulfill their biological function. DNA repair pathways function in germ cells and serve to ameliorate much DNA damage and prevent mutagenesis. High base excision repair (BER) activity is documented for spermatogenic cells. DNA polymerase-beta (POLB) is required for the short-patch BER pathway. Because mice homozygous null for the Polb gene die soon after birth, mice heterozygous for Polb were used to examine the extent to which POLB contributes to maintaining spermatogenic genomic integrity in vivo. POLB protein levels were reduced only in mixed spermatogenic cells. In vitro short-patch BER activity assays revealed that spermatogenic cell nuclear extracts obtained from Polb heterozygous mice had one third the BER activity of age-matched control mice. Polb heterozygosity had no effect on the BER activities of somatic tissues tested. The Polb heterozygous mouse line was crossed with the lacI transgenic Big Blue mouse line to assess mutant frequency. The spontaneous mutant frequency for mixed spermatogenic cells prepared from Polb heterozygous mice was 2-fold greater than that of wild-type controls, but no significant effect was found among the somatic tissues tested. These results demonstrate that normal POLB abundance is necessary for normal BER activity, which is critical in maintaining a low germline mutant frequency. Notably, spermatogenic cells respond differently than somatic cells to Polb haploinsufficiency.

Gonadotropin-regulated testicular helicase (DDX25), an essential regulator of spermatogenesis, prevents testicular germ cell apoptosis

Gonadotropin-regulated testicular helicase (GRTH)/DDX25 is an essential post-transcriptional regulator of spermatogenesis. In GRTH null mice severe apoptosis was observed in spermatocytes entering the metaphase of meiosis. Pro- and anti-apoptotic factors were found to be under GRTH regulation in comparative studies of spermatocytes from wild type and GRTH(-/-) knock-out (KO) mice. KO mice displayed decreased levels of Bcl-2 and Bcl-xL (anti-apoptotic factors), an increase in Bid, Bak, and Bad (pro-apoptotic), reduced phospho-Bad, and release of cytochrome c. Also, an increase on Smac, a competitor of inhibitor apoptotic proteins that release caspases, was observed. These changes caused an increase in cleavage of caspases 9 and 3, activation of caspase 3 and increases in cleavage products of PARP. The half-life of caspase 3 transcripts was markedly increased in KO, indicating that GRTH had a negative role on its mRNA stability. IkappaBalpha, which sequesters NF-kappaB from its transcriptional activation of pro-apoptotic genes, was highly elevated in KO, and its phospho-form, which promotes its dissociation, was reduced. The increase of HDAC1 and abolition of p300 expression in KO indicated a nuclear action of GRTH on the NF-kappaB-mediated transcription of anti-apoptotic genes. It also regulates the associated death domain pathway and caspase 8-mediated events. GRTH-mediated apoptotic regulation was further indicated by its selective binding to pro- and anti-apoptotic mRNAs. These studies have demonstrated that GRTH, as a component of mRNP particles, acts as a negative regulator of the tumor necrosis factor receptor 1 and caspase pathways and promotes NF-kappaB function to control apoptosis in spermatocytes of adult mice.