Transformation, migration and outcome of residual bodies in the seminiferous tubules of the rat testis

DNAJA1 regulates protein ubiquitination and is essential for spermatogenesis in the testes of mice and rats

DNAJA1 is a member of type I DnaJ proteins, which is essential for spermatogenesis and male fertility. However, its expression pattern in the testes and its impact on spermatogenesis remains unclear. Our study aimed to elucidate the mechanism of action of DNAJA1. We employed DNAJA1 knockout mice in this study. Western blotting and immunofluorescence analysis were conducted to determine the protein abundance of DNAJA1 in testes at various developmental stages. Our results revealed that DNAJA1 is predominantly expressed in the testes, and its knockout leads to complete infertility in male mice. We observed that DNAJA1 protein levels increased on postnatal days 14, 21, and 28, peaking on postnatal day 35 in mice. Immunofluorescence staining indicated that DNAJA1 expression varies across different stages of the spermatogenesis cycle. Additionally, DNAJA1 was absent in epididymal sperm. In early- and mid-stage tubules, DNAJA1 protein distribution was co-localized with residual bodies in elongating spermatids. Furthermore, we found that DNAJA1 knockout significantly reduced protein polyubiquitination in the testis. Analysis of the GEO database showed that DNAJA1 levels were significantly decreased in semen samples from subjects with teratozoospermia, asthenozoospermia, and impaired spermatogenesis. Our findings suggest that DNAJA1 is an essential protein for spermatogenesis, and its deletion reduces protein polyubiquitination in the testis, ultimately resulting in infertility and spermatogenesis defects.

Sperm function, mitochondrial activity and in vivo fertility are associated to their mitochondrial DNA content in pigs

BACKGROUND

Despite their low abundance in sperm, mitochondria have diverse functions in this cell type, including energy production, signalling and calcium regulation. In humans, sperm mitochondrial DNA content (mtDNAc) has been reported to be negatively linked to sperm function and fertility. Yet, the association between mtDNAc and sperm function in livestock remains unexplored. For this reason, this study aimed to shed some light on the link between mtDNAc and sperm function and fertilising potential in pigs. A qPCR method for mtDNAc quantification was optimised for pig sperm, and the association of this parameter with sperm motility, kinematics, mitochondrial activity, and fertility was subsequently interrogated.

RESULTS

First, the qPCR method was found to be sensitive and efficient for mtDNAc quantification in pig sperm. By using this technique, mtDNAc was observed to be associated to sperm motility, mitochondrial activity and in vivo, but not in vitro, fertility outcomes. Specifically, sperm with low mtDNAc were seen to exhibit greater motility but decreased mitochondrial activity and intracellular reactive oxygen species. Interestingly, samples with lower mtDNAc showed higher conception and farrowing rates, but similar in vitro fertilisation rates and embryo development, when compared to those with greater mtDNAc.

CONCLUSIONS

These findings enrich our comprehension of the association of mtDNAc with sperm biology, and lay the foundation for future research into employing this parameter as a molecular predictor for sperm function and fertility in livestock.

An Improved Method for Purification of the Residual Bodies from the Seminiferous Tubules of Mice

Human fertility is declining in Western countries, and it is becoming increasingly clear that male infertility plays a pivotal role in the overall fertility decline. To understand the process that drives successful male germ cell maturation, the study of spermatogenesis of model organisms, such as mice, is essential. Residual bodies (RBs) play an important role in the last stages of spermatogenesis. They are formed at the time when post-meiotic spermatids undergo sequential differentiation steps so that the acrosome and flagellum are developed, the nucleus is markedly condensed, and the cytoplasm is lost. The masses of lost cytoplasm become RBs. Our recent work has shown that RB dynamics are highly sensitive to even small fertility defects. It was also noted that the transcriptome and proteome of RBs changes in response to spermatogenic defects. Thus, RBs represent an excellent and highly sensitive entity for studying male fertility. Previously published protocols for RB purification had some major limitations: they produced an RB fraction that was heavily contaminated with spermatozoa and erythrocytes or required tens of grams of starting material. In addition, most of the available protocols were developed for purification of RBs from rat testes. Here, we present a protocol that allows the isolation of 2.5-3 × 106 RBs from mouse testes with a purity of 98% from only 1 g of starting material. The purified material can be used for various downstream applications to study male fertility, such as transcriptome and proteome analyses, super-resolution microscopy, and electron and cryo-electron microscopy, amongst many others. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: An improved method for purification of the residual bodies from the seminiferous tubules of mice.

Exposed and Sequestered Antigens in Testes and Their Protection by Regulatory T Cell-Dependent Systemic Tolerance

Continuous exposure of tissue antigen (Ag) to the autoantigen-specific regulatory T cells (Treg) is required to maintain Treg-dependent systemic tolerance. Thus, testis autoantigens, previously considered as sequestered, may not be protected by systemic tolerance. We now document that the complete testis antigen sequestration is not valid. The haploid sperm Ag lactate dehydrogenase 3 (LDH3) is continuously exposed and not sequestered. It enters the residual body (RB) to egress from the seminiferous tubules and interact with circulating antibody (Ab). Some LDH3 also remains inside the sperm cytoplasmic droplets (CD). Treg-depletion in the DEREG mice that express diphtheria toxin receptor on the Foxp3 promoter results in spontaneous experimental autoimmune orchitis (EAO) and Ab to LDH3. Unlike the wild-type male mice, mice deficient in LDH3 (wild-type female or LDH3 NULL males) respond vigorously to LDH3 immunization. However, partial Treg depletion elevated the wild-type male LDH3 responses to the level of normal females. In contrast to LDH3, zonadhesin (ZAN) in the sperm acrosome displays properties of a sequestered Ag. However, when ZAN and other sperm Ag are exposed by vasectomy, they rapidly induce testis Ag-specific tolerance, which is terminated by partial Treg-depletion, leading to bilateral EAO and ZAN Ab response. We conclude that some testis/sperm Ag are normally exposed because of the unique testicular anatomy and physiology. The exposed Ag: 1) maintain normal Treg-dependent systemic tolerance, and 2) are pathogenic and serve as target Ag to initiate EAO. Unexpectedly, the sequestered Ags, normally non-tolerogenic, can orchestrate de novo Treg-dependent, systemic tolerance when exposed in vasectomy.

Sperm proteins and cancer-testis antigens are released by the seminiferous tubules in mice and men

Sperm develop from puberty in the seminiferous tubules, inside the blood-testis barrier to prevent their recognition as "non-self" by the immune system, and it is widely assumed that human sperm-specific proteins cannot access the circulatory or immune systems. Sperm-specific proteins aberrantly expressed in cancer, known as cancer-testis antigens (CTAs), are often pursued as cancer biomarkers and therapeutic targets based on the assumption they are neoantigens absent from the circulation in healthy men. Here, we identify a wide range of germ cell-derived and sperm-specific proteins, including multiple CTAs, that are selectively deposited by the Sertoli cells of the adult mouse and human seminiferous tubules into testicular interstitial fluid (TIF) that is "outside" the blood-testis barrier. From TIF, the proteins can access the circulatory- and immune systems. Disruption of spermatogenesis decreases the abundance of these proteins in mouse TIF, and a sperm-specific CTA is significantly decreased in TIF from infertile men, suggesting that exposure of certain CTAs to the immune system could depend on fertility status. The results provide a rationale for the development of blood-based tests useful in the management of male infertility and indicate CTA candidates for cancer immunotherapy and biomarker development that could show sex-specific and male-fertility-related responses.

The multiple roles of RAB GTPases in female and male meiosis

BACKGROUND

RAB GTPases constitute the largest family of small GTPases and are found in all eukaryotes. RAB GTPases regulate components of the endomembrane system, the nucleus and the plasma membrane, and are involved in intracellular actin/tubulin-dependent vesicle movement, membrane fusion and cell growth in mitosis.

OBJECTIVE AND RATIONALE

RAB GTPases play multiple critical roles during both female and male meiosis. This review summarizes the progress made in our understanding of the role of RAB GTPases in female and male meiosis in different species. We also discuss the potential relationship between RAB GTPases and oocyte/sperm quality, which may help in understanding the mechanisms underlying oogenesis and spermatogenesis and potential genetic causes of infertility.

SEARCH METHODS

The PubMed database was searched for articles published between 1991 and 2020 using the following terms: 'RAB', 'RAB oocyte', 'RAB sperm' and 'RAB meiosis'.

OUTCOMES

An analysis of 126 relevant articles indicated that RAB GTPases are present in all eukaryotes, and ten subfamilies (almost 70 members) are expressed in human cells. The roles of 25 RAB proteins and orthologues in female meiosis and 12 in male meiosis have been reported. RAB proteins are essential for the accurate continuity of genetic material, successful fertilization and the normal growth of offspring. Distinct and crucial functions of RAB GTPases in meiosis have been reported. In oocytes, RAB GTPases are involved in spindle organization, kinetochore-microtubule attachment, chromosome alignment, actin filament-mediated spindle migration, cytokinesis, cell cycle and oocyte-embryo transition. RAB GTPases function in mitochondrial processes and Golgi-mediated vesicular transport during female meiosis, and are critical for cortical granule transport during fertilization and oocyte-embryo transition. In sperm, RAB GTPases are vital for cytoskeletal organization and successful cytokinesis, and are associated with Golgi-mediated acrosome formation, membrane trafficking and morphological changes of sperm cells, as well as the exocytosis-related acrosome reaction and zona reaction during fertilization.

WIDER IMPLICATIONS

Abnormal expression of RAB GTPases disrupts intracellular systems, which may induce diverse diseases. The roles of RAB proteins in female and male reproductive systems, thus, need to be considered. The mechanisms underlying the function of RAB GTPases and the binding specificity of their effectors during oogenesis, spermatogenesis and fertilization remain to be studied. This review should contribute to our understanding of the molecular mechanisms of oogenesis and spermatogenesis and potential genetic causes of infertility.

Advances on hormone-like activity of Panax ginseng and ginsenosides

Traditional Chinese medicine (TCM) has been paid much attentions due to the prevention and treatment of steroid hormone disorders. Ginseng, the root of Panax ginseng C. A. Meyer (Araliaceae), is one of the most valuable herbs in complementary and alternative medicines around the world. A series of dammarane triterpenoid saponins, also known as phytosteroids, were reported as the primary ingredients of Ginseng, and indicated broad spectral pharmacological actions, including anti-cancer, anti-inflammation and anti-fatigue. The skeletons of the dammarane triterpenoid aglycone are structurally similar to the steroid hormones. Both in vitro and in vivo studies showed that Ginseng and its active ingredients have beneficial hormone-like role in hormonal disorders. This review thus summarizes the structural similarities between hormones and dammarane ginsenosides and integrates the analogous effect of Ginseng and ginsenosides on prevention and treatment of hormonal disorders published in recent twenty years (1998-2018). The review may provide convenience for anticipate structure-function relationship between saponins structure and hormone-like effect.

BXSB/MpJ-Yaa mouse model of systemic autoimmune disease shows increased apoptotic germ cells in stage XII of the seminiferous epithelial cycle

In mammals, the reproductive system and autoimmunity regulate mutual functions. Importantly, systemic autoimmune diseases are thought to cause male infertility but the underlying pathological mechanism remains unclear. In this study, the morpho-function of the testes in BXSB/MpJ-Yaa mice was analyzed as a representative mouse model for systemic autoimmune diseases to investigate the effect of excessive autoimmunity on spermatogenesis. At 12 and 24 weeks of age, BXSB/MpJ-Yaa mice showed splenomegaly and increased levels of serum autoantibodies, whereas no controls showed a similar autoimmune condition. In histological analysis, the enlarged lumen of the seminiferous tubules accompanied with scarce spermatozoa in the epididymal ducts were observed in some of the BXSB/MpJ-Yaa and BXSB/MpJ mice but not in C57BL/6N mice. Histoplanimetrical analysis revealed significantly increased residual bodies and apoptotic germ cells in the seminiferous tubules in BXSB/MpJ-Yaa testes without apparent inflammation. Notably, in stage XII of the seminiferous epithelial cycles, the apoptotic germ cell number was remarkably increased, showing a significant correlation with the indices of systemic autoimmune disease in BXSB/MpJ-Yaa mice. Furthermore, the Sertoli cell number was reduced at the early disease stage, which likely caused subsequent morphological changes in BXSB/MpJ-Yaa testes. Thus, our histological study revealed the altered morphologies of BXSB/MpJ-Yaa testes, which were not observed in controls and statistical analysis suggested the effects of an autoimmune condition on this phenotype, particularly the apoptosis of meiotic germ cells. BXSB/MpJ-Yaa mice were shown to be an efficient model to study the relationship between systemic autoimmune disease and the local reproductive system.