Androgen-Regulated Genes in the Murine Epididymis1

Acute effects of atrazine on the immunoexpressions of sertoli and germ cells molecular markers, cytokines, chemokines, and sex hormones levels in mice testes and epididymides

Atrazine is currently one of the most commonly used agrochemicals in the United States and elsewhere. Here, we studied the immunoexpression of molecular markers of mammalian testicular functions: androgen receptor (AR), promyelocytic leukemia zinc finger (PLZF), GDNF family receptor alpha-1 (GFRA1), VASA/DDX4 (DEAD-Box Helicase 4) as well as the levels of intratesticular and intra-epididymal estradiol (E2) and dihydrotestosterone (DHT), tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukins (IL-1β and IL-6, IL-10) and testicular chemokines (CXCL-1, CCL-2 and CCL3) in BalB/c mice after a sub-acute gavage treatment with a gonado-toxin, atrazine (50 mg/kg body wt.) for three days. We found high numbers of AR immunopositive Sertoli cells and low numbers of GFRA1, PLZF and VASA/DDX4-positive germ cells in the seminiferous tubule regions of the testes. While TNF-α level in the testes fell and remained unchanged in the epididymides, IFN-γ levels in the testes remained constant but increased in the epididymides. E2 and DHT concentrations remained unaltered in the testes but were changed in the epididymides. There were no significant changes in the levels of interleukins in the testis and epididymis. Intratesticular chemokines were also not significantly altered, except for CCL-4, which was increased in the testis. Light microscopy of the epididymis showed detached epithelium and some detached cells in the lumen. It is concluded that atrazine changed the inflammatory status of the gonads and highlighted Sertoli and undifferentiated spermatogonia as important targets for atrazine's toxic effects in the testis of mice. Concerning the epididymis, atrazine altered the epididymal hormonal concentrations and promoted histopathological modifications in its parenchyma.

Distinct actions of testicular endocrine and lumicrine signaling on the proximal epididymal transcriptome

The epididymal function and gene expression in mammals are under the control of the testis. Sex steroids are secreted from the testis and act on the epididymis in an endocrine manner. There is another, non-sex steroidal secreted signaling, named lumicrine signaling, in which testis-derived secreted proteins go through the male reproductive tract and act on the epididymis. The effects of such multiple regulations on the epididymis by the testis have been investigated for many genes. The recent development of high-throughput next-generation sequencing now enables us a further comparative survey of endocrine and lumicrine action-dependent gene expression. In the present study, testis-derived endocrine and lumicrine actions on epididymal gene expression were comparatively investigated by RNA-seq transcriptomic analyses. This investigation utilized experimental animal models in which testis-derived endocrine and/or lumicrine actions were interfered with, such as unilateral or bilateral orchidectomy. By bilateral orchidectomy, which interferes with both endocrine and lumicrine actions, 431 genes were downregulated. By unilateral orchidectomy, which also interferes with endocrine and lumicrine actions by the unilateral testis, but the endocrine action was compensated by the contralateral testis, 283 genes were downregulated. The content of such genes downregulated by unilateral orchidectomy was like those of lumicrine action-interfered efferent duct-ligation, W/Wv, and Nell2-/- mice. When genes affected by unilateral and bilateral orchidectomy were compared, 154 genes were commonly downregulated, whereas 217 genes were specifically downregulated only by bilateral orchidectomy, indicating the distinction between endocrine and lumicrine actions on the proximal epididymal transcriptome. Comparative transcriptome analyses also showed that the expressions of genes emerging since Amniota were notably impacted by bilateral orchidectomy, unilateral orchidectomy, and lumicrine action-interfering treatments; the degree of influence from these treatments varied based on the evolutionary stage beyond Amniota. These findings unveil an evolutional transition of regulated gene expression in the proximal epididymis by two different testis-derived signaling mechanisms.

Busulfan administration replicated the characteristics of the epididymal initial segment observed in mice lacking testis-epididymis lumicrine signaling

The physiological functions of the mammalian epididymis are typically regulated by the testes. In addition to sex steroids secreted by testicular Leydig cells, which act on the epididymis in an endocrine manner, there is a non-sex-steroidal signaling pathway known as the lumicrine pathway. This lumicrine signaling pathway involves ligand proteins secreted from germ cells within the testicular seminiferous tubules traversing the male reproductive tract, which induce epithelial differentiation in the epididymis. These findings prompted an inquiry into whether treatments influencing testis physiology can disrupt epididymal function by interfering with testis-epididymis communication. Busulfan, an alkylating agent commonly used to deplete testicular germ cells in reproductive biology, has not been sufficiently explored because of its effects on the epididymis. This study investigated the effects of busulfan administration on the proximal epididymis using histological and transcriptomic analyses. Notably, busulfan, as opposed to the vehicle dimethyl sulfoxide (DMSO), altered the morphology of the initial segment of the epididymis, leading to a reduction in the cell height of the luminal epithelium. RNA sequencing identified 185 significantly downregulated genes in the proximal epididymis of busulfan-administered mice compared to DMSO-administered mice. Comparative transcriptome analyses revealed similarities between the epididymal transcriptome of busulfan-administered mice and lumicrine-deficient mice, such as efferent-duct-ligated W/Wv and Nell2-/- mice. However, this differed from that of bilaterally orchidectomized mice, in which both the endocrine and lumicrine signaling pathways were simultaneously ablated. Collectively, these results suggested that the harmful effects of busulfan on the proximal epididymis are secondary consequences of the ablation of testis-epididymis lumicrine signaling.

The significance of single-cell transcriptome analysis in epididymis research

As a crucial component of the male reproductive system, the epididymis plays multiple roles, including sperm storage and secretion of nutritive fluids for sperm development and maturation. The acquisition of fertilization capacity by sperm occurs during their transport through the epididymis. Compared with the testis, little has been realized about the importance of the epididymis. However, with the development of molecular biology and single-cell sequencing technology, the importance of the epididymis for male fertility should be reconsidered. Recent studies have revealed that different regions of the epididymis exhibit distinct functions and cell type compositions, which are likely determined by variations in gene expression patterns. In this research, we primarily focused on elucidating the cellular composition and region-specific gene expression patterns within different segments of the epididymis and provided detailed insights into epididymal function in male fertility.

Transcriptome profiling of the initial segment and proximal caput of mouse epididymis

Background

The proximal region of the mouse epididymis plays a pivotal role in sperm transport, sperm maturation, and male fertility. Several studies have focused on segment-dependent gene expression of the mouse epididymis through high-throughput sequencing without the precision of the microdissection.

Methods and results

Herein, we isolated the initial segment (IS) and proximal caput (P-caput) by physical microdissection using an Lcn9-cre; Rosa26tdTomato mouse model. We defined the transcriptome changes of caput epididymis by RNA sequencing (RNA-seq), which identified 1,961 genes that were abundantly expressed in the IS and 1,739 genes that were prominently expressed in the P-caput. In addition, we found that many differentially expressed genes (DEGs) were predominantly or uniquely expressed in the epididymis and region-specific genes were highly associated with transport, secretion, sperm motility, fertilization, and male fertility.

Conclusion

Thus, this study provides an RNA-seq resource to identify region-specific genes in the caput epididymis. The epididymal-selective/specific genes are potential targets for male contraception and may provide new insights into understanding segment-specific epididymal microenvironment-mediated sperm transport, maturation, and male fertility.

Declined expressing mRNA of beta-defensin 108 from epididymis is associated with decreased sperm motility in blue fox (Vulpes lagopus)

BACKGROUND

Fecundity is important for farm blue fox (Vulpes lagopus), who with asthenospermia have be a problem in some of farms in China. A key symptom of asthenospermia is decreased sperm motility. The decreased secreting beta-defensin108 (vBD108) of blue fox is speculated be related to asthenospermia. To clarify this idea, the mRNA expression of vBD108 in testis and epididymis of blue foxes with asthenospermia were detected and compared to the healthy one. The antibody was prepared and analyzed by immunohistochemistry.

RESULTS

The vBD108 in testis and epididymis was found both in blue fox with asthenospermia and healthy group by the method of immunohistochemistry. The expression of vBD108 mRNA in testes (P < 0.05) and epididymal corpus (P < 0.0001) in asthenospermia group was lower than that in healthy group.

CONCLUSIONS

These results suggested that vBD108 deficiency may related to blue fox asthenospermia. Meanwhile, the study on the blue fox vBD108 provides a hopeful direction to explore the pathogenesis of blue fox asthenospermia in the future.

Transcriptome analysis of the epididymis from Plag1 deficient mice suggests dysregulation of sperm maturation and extracellular matrix genes

BACKGROUND

The transcription factor pleomorphic adenoma gene 1 (PLAG1) is required for male fertility. Mice deficient in PLAG1 exhibit decreased sperm motility and abnormal epididymal tubule elongation and coiling, indicating impaired sperm maturation during epididymal transit. However, the downstream transcriptomic profile of the Plag1 knockout (KO; Plag1^-/- ) murine epididymis is currently unknown.

RESULTS

In this study, the PLAG1-dependent epididymal transcriptome was characterised using RNA sequencing. Several genes important for the control of sperm maturation, motility, capacitation and the acrosome reaction were dysregulated in Plag1^-/- mice. Surprisingly, several cell proliferation genes were upregulated, and Ki67 analysis indicated that cell proliferation is aberrantly upregulated in the cauda epididymis stroma of Plag1^-/- mice. Gene ontology analysis showed an overall upregulation of genes encoding extracellular matrix components, and an overall downregulation of genes encoding metalloendopeptidases in the epididymides from Plag1^-/- mice.

CONCLUSION

Together, these results suggest a defect in the epididymal extracellular matrix in Plag1^-/- mice. These results imply that in addition to maintaining epididymal integrity directly, PLAG1 may also regulate several genes involved in the regulation of sperm maturation and capacitation. Moreover, PLAG1 may also be involved in regulating tissue homeostasis and ensuring proper structure and maintenance of the extracellular matrix in the epididymis.

Epididymal contribution to male infertility: An overlooked problem

The diagnosis and treatment of male infertility, excluding assisted conception, are limited because of, but not limited to, poor understanding of sperm post-testicular development and storage. Many may think that sperm dysfunction is only self-contained in the sperm cell itself as a result of defective spermatogenesis. However, it can also be a consequence of inadequate epididymal maturation following disorders of the epididymis. Improper epididymal functions can disturb semen parameters and sperm DNA integrity, result in high leucocyte concentrations and high numbers of immature germ cells and debris or even cause idiopathic infertility. To date, the data are limited regarding critical markers of sperm maturation and studies that can identify such markers for diagnosis and managing epididymal dysfunction are scarce. Therefore, this article aims to draw attention to recognise a disturbed epididymal environment as a potential cause of male infertility.

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

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

A novel transcriptional network for the androgen receptor in human epididymis epithelial cells

STUDY QUESTION

What is the transcriptional network governed by the androgen receptor (AR) in human epididymis epithelial (HEE) cells from the caput region and if the network is tissue-specific, how is this achieved?

SUMMARY ANSWER

About 200 genes are differentially expressed in the caput HEE cells after AR activation; the AR transcriptional network is tissue-specific and may be mediated in part by distinct AR co-factors including CAAT-enhancer binding protein beta (CEBPB) and runt-related transcription factor 1 (RUNX1).

WHAT IS KNOWN ALREADY

Little is known about the AR transcriptional program genome wide in HEE cells, nor its co-factors in those cells. AR has been best studied in the prostate gland epithelium and prostate cancer cell lines, due to the important role of this factor in prostate cancer. However AR-associated differentially expressed genes (DEGs) and AR co-factors have not yet been compared between human epididymis and prostate epithelial cells.

STUDY DESIGN, SIZE, DURATION

Caput HEE cells from two donors were exposed to the synthetic androgen R1881 at 1 nM for 12-16 h after 72 h of hormone starvation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Chromatin was prepared from R1881-treated and vehicle control HEE cells. AR-associated chromatin was purified by chromatin immunoprecipitation (ChIP) and AR occupancy genome wide was revealed by deep sequencing (ChIP-seq). Two independent biological replicates were performed. Total RNA was prepared from R1881 and control-treated HEE cells and gene expression profiles were documented by RNA-seq. The interaction of the potential novel AR co-factors CEBPB and RUNX1, identified through in-silico motif analysis of AR ChIP-seq data, was examined by ChIP-qPCR after siRNA-mediated depletion of each co-factor individually or simultaneously.

MAIN RESULTS AND THE ROLE OF CHANCE

The results identify about 200 genes that are differentially expressed (DEGs) in HEE cells after AR activation. Some of these DEGs show occupancy of AR at their promoters or cis-regulatory elements suggesting direct regulation. However, there is little overlap in AR-associated DEGs between HEE and prostate epithelial cells. Inspection of over-represented motifs in AR ChIP-seq peaks identified CEBPB and RUNX1 as potential co-factors, with no evidence for FOXA1, which is an important co-factor in the prostate epithelium. CEBPB and RUNX1 ChIP-seq in HEE cells showed that both these factors often occupied AR-binding sites, though rarely simultaneously. Further analysis at a single AR-regulated locus (FK506-binding protein 5, FKPB5) suggests that CEBPB may be a co-activator. These data suggest a novel AR transcriptional network governs differentiated functions of the human epididymis epithelium.

LARGE SCALE DATA

AR ChIP-seq and RNA-seq data are deposited at GEO: GSE109063.

LIMITATIONS, REASONS FOR CAUTION

There is substantial donor-to-donor variation in primary HEE cells cultures. We applied stringent statistical tests with a false discovery rate (FDR) of 0.1% for ChIP-seq and standard pipelines for RNA-seq so it is possible that we have missed some AR-regulated genes that are important in caput epididymis function.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest that a novel AR transcriptional network governs differentiated functions of the human epididymis epithelium. Since this cell layer has a critical role in normal sperm maturation, the results are of broader significance in understanding the mechanisms underlying the maintenance of fertility in men.

STUDY FUNDING/COMPETING INTERESTS

This work was funded by the National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Development: R01 HD068901 (PI: Harris). The authors have no competing interests to declare.

Androgen signaling regulates the transcription of anti-Müllerian hormone via synergy with SRY-related protein SOX9A

Anti-Müllerian hormone (amh) is one of the earliest functional genes expressed during testicular differentiation. It has been suggested that androgen signaling regulates critical genes for the differentiation and development of the testis. To elucidate the exact regulatory mechanisms involved in amh transcription mediated by androgen signaling, androgen signaling was manipulated in zebrafish by cytochrome P450 17a1 (cyp17a1) knockout and Flutamide treatment. In cyp17a1-deficient and Flutamide-treated testes, up-regulated sry-box9a (sox9a) and down-regulated amh were observed. Moreover, a physical association of the zebrafish androgen receptor (AR) and SOX9A was found. The interaction between AR and SOX9A was mediated via the DNA binding domain (DBD) of AR and the transactivation domain (TA) of SOX9A, and was further enhanced by 5-alpha dihydrotestosterone (DHT), one of the most potent androgens. Intriguingly, together with SOX9A, androgen signaling synergistically promoted amh transcription, mainly through the proximal 1kb of the amh promoter region. Taken together, our data demonstrate a critical mechanism underlying the direct synergy of androgen signaling and SOX9A in the regulation of amh transcription.

Body mass index and human sperm quality: neither one extreme nor the other

The aim of the present study was to investigate the still contentious association between body mass index (BMI) and seminal quality. To this end, 4860 male patients (aged 18–65 years; non-smokers and non-drinkers), were classified according to BMI as either underweight (UW; BMI <20 kg m–2; n = 45), normal weight (NW; BMI 20–24.9 kg m–2; n = 1330), overweight (OW; BMI 25–29.9 kg m–2; n = 2493), obese (OB; BMI 30–39.9 kg m–2; n = 926) or morbidly obese (MOB; BMI ≥40 kg m–2; n = 57). Conventional semen parameters and seminal concentrations of fructose, citric acid and neutral α-glucosidase (NAG) were evaluated. The four parameters that reflect epididymal maturation were significantly lower in the UW and MOB groups compared with NW, OW and OB groups: sperm concentration, total sperm count (103.3 ± 11.4 and 121.5 ± 20.6 and vs 157.9 ± 3.6, 152.4 ± 2.7 or 142.1 ± 4.3 spermatozoa ejaculate–1 respectively, P < 0.05), motility (41.8 ± 2.5 and 42.6 ± 2.6 vs 47.8 ± 0.5, 48.0 ± 0.4 or 46.3 ± 0.6 % of motile spermatozoa respectively, P < 0.05) and NAG (45.2 ± 6.6 and 60.1 ± 7.9 vs 71.5 ± 1.9, 64.7 ± 1.3 or 63.1 ± 2.1 mU ejaculate-1 respectively, P < 0.05). Moreover, the percentage of morphologically normal spermatozoa was decreased in the MOB group compared with the UW, NW, OW and OB groups (4.8 ± 0.6% vs 6.0 ± 0.8%, 6.9 ± 0.1%, 6.8 ± 0.1 and 6.4 ± 0.2%, respectively; P < 0.05). In addition, men in the MOB group had an increased risk (2.3- to 4.9-fold greater) of suffering oligospermia and teratospermia (P < 0.05). Both morbid obesity and being underweight have a negative effect on sperm quality, particularly epididymal maturation. These results show the importance of an adequate or normal bodyweight as the natural best option for fertility, with both extremes of the BMI scale as negative prognostic factors.

Accumulation of trans-1-amino-3-[(18)F]fluorocyclobutanecarboxylic acid in prostate cancer due to androgen-induced expression of amino acid transporters

PURPOSE

Androgens play a crucial role in prostate cancer progression, and trans-1-amino-3-[(18)F]fluorocyclobutanecarboxylic acid (anti-[(18) F]FACBC) are used for visualization of prostate cancer. We examined the effect of androgen on the expression of amino acid transporters related to anti-[(18)F]FACBC transport and uptake of trans-1-amino-3-fluoro-[1-(14)C]cyclobutanecarboxylic acid (anti-[(14)C]FACBC).

PROCEDURES

Expression of amino acid transporters and uptake of anti-[(14)C]FACBC in androgen receptor (AR)-positive LNCaP and AR-negative DU145 human prostate cancer cells cultured with/without 5α-dihydrotestosterone (DHT) and the effect of bicalutamide, an AR antagonist, on DHT-associated changes were investigated.

RESULTS

DHT stimulated the expression of amino acid transporters ASCT2, SNAT5, 4F2 heavy chain, and LAT3 in LNCaP but not in DU145 cells. Anti-[(14)C]FACBC uptake was enhanced, in a DHT-dependent manner, in LNCaP cells only.

CONCLUSIONS

DHT enhanced the expression of ASCT2, the transporter responsible for anti-[(18)F]FACBC uptake, thereby increasing anti-[(14)C]FACBC uptake in AR-positive LNCaP cells. Androgen-mediated induction may contribute to the distinct anti-[(18)F]FACBC accumulation pattern in prostate cancer.

Steroid regulation of early postnatal development in the corpus epididymidis of pigs

Development of the epididymis including blood-epididymal barrier formation is not required until sperm reach the epididymis peripuberally. Regulation of this development in the early postnatal period is largely unknown. The current objectives were to evaluate potential roles of endogenous estrogen and androgen signaling during early development of the corpus epididymidis and to determine the timing of formation of the blood-epididymal barrier in the pig. Effects of endogenous steroids were evaluated using littermates treated with vehicle, an aromatase inhibitor (letrozole) to reduce endogenous estrogens, an estrogen receptor antagonist (fulvestrant) or an androgen receptor antagonist (flutamide). Phosphorylated histone 3 immunohistochemistry was used to identify proliferating epithelial cells. Lanthanum nitrate and electron microscopy were used to analyze formation of the blood barrier in the corpus epididymidis. Reducing endogenous estrogens increased the number of proliferating corpus epithelial cells at 6 and 6.5 weeks of age compared with vehicle-treated boars (P<0.01 and P<0.001 respectively). Blocking androgen receptors did not alter proliferation rate at 6.5 weeks of age. Although barrier formation was similar between 6 and 6.5 weeks of age in vehicle-treated animals, intercellular barriers increased in letrozole-treated littermates at 6.5 weeks of age. Fulvestrant treatment, which should mimic aromatase inhibition for regulation through ESR1 and ESR2 signaling but potentially stimulate endogenous estrogen signaling through the G protein-coupled estrogen receptor (GPER), had the opposite effect on aromatase inhibition. These responses in conjunction with the presence of GPER in the corpus epididymidis suggest early corpus epididymal development is regulated partially by GPER.

Epididymal Region-Specific miRNA Expression and DNA Methylation and Their Roles in Controlling Gene Expression in Rats

Region-specific gene expression is an intriguing feature of the mammalian epididymis. This unique property is essential for sperm maturation and storage, and it also implicates stringent and multi-level regulations of gene expression. Over the past decade, the androgen-driven activation of epididymal gene transcription has been extensively studied. However, it still remains largely unexplored whether and how other regulatory mechanisms, such as miRNAs and DNA methylation, are involved in controlling regional gene expression in the epididymis. Using microarray-based approaches, we studied the regional miRNA expression and DNA methylation profiles in 4 distinct epididymal regions (initial segment, caput, corpus and cauda) of rats. We found that the miR-200 family members were more expressed in caput, compared with cauda. By GSEA analysis, the differential expression of miR-200 family between caput and cauda was shown to be negatively correlated with their predicted target genes, among which 4 bona fide targets were verified by luciferase reporter assay. Predicted target genes of miR-200 family have enriched functions in anti-apoptosis, cell transportation and development, implying the regional diversity in epididymal functions. On the other hand, we revealed epididymal DNA methylation of 2002 CpG islands and 2771 gene promoters (-3.88-0.97 kb), among which 1350 (67.43%) CpG islands and 2095 (75.60%) promoters contained region-specific DNA methylation. We observed significant and distinct functional enrichment in genes with specifically methylated promoters in each epididymal regions, but these DNA methylations did not show significant correlation with repressed gene transcription in the mature epididymis. Conclusively, we investigated the regional miRNA expression and DNA methylation in the rat epididymis and revealed a potential role of miR-200 family in gene expression regulation between caput and cauda. This may contribute to the distinct physiological function in sperm maturation / storage of caput / cauda epididymis.

New insight into the castrated mouse epididymis based on comparative proteomics

The mammalian epididymis is an important male accessory gland where the spermatozoa gain the ability to fertilise the egg. To further understand the effects of testicular factors on the epididymis, the proteome of castrated adult mice and sham controls was compared using high-resolution two-dimensional gel electrophoresis following identification of proteins by matrix-assisted laser desorption ionisation time-of-flight/time-of-flight mass spectrometry. Twenty-three differentially expressed proteins (11 upregulated and 12 downregulated) were identified in epididymides from castrated. Bioinformatic analysis indicated that these castration-responsive proteins participated in energy metabolism and the antigen processing and presentation pathway. The differential expression levels were further validated by western blotting. The differentially expressed proteins may serve as potential candidates in studies of epididymal function and male infertility.

Characterization of primary cultures of adult human epididymis epithelial cells

OBJECTIVE

To establish cultures of epithelial cells from all regions of the human epididymis to provide reagents for molecular approaches to functional studies of this epithelium.

DESIGN

Experimental laboratory study.

SETTING

University research institute.

PATIENT(S)

Epididymis from seven patients undergoing orchiectomy for suspected testicular cancer without epididymal involvement.

INTERVENTION(S)

Human epididymis epithelial cells harvested from adult epididymis tissue.

MAIN OUTCOME MEASURE(S)

Establishment of a robust culture protocol for adult human epididymal epithelial cells.

RESULT(S)

Cultures of caput, corpus, and cauda epithelial cells were established from epididymis tissue of seven donors. Cells were passaged up to eight times and maintained differentiation markers. They were also cryopreserved and recovered successfully. Androgen receptor, clusterin, and cysteine-rich secretory protein 1 were expressed in cultured cells, as shown by means of immunofluorescence, Western blot, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The distribution of other epididymis markers was also shown by means of qRT-PCR. Cultures developed transepithelial resistance (TER), which was androgen responsive in the caput but androgen insensitive in the corpus and cauda, where unstimulated TER values were much higher.

CONCLUSION(S)

The results demonstrate a robust in vitro culture system for differentiated epithelial cell types in the caput, corpus, and cauda of the human epididymis. These cells will be a valuable resource for molecular analysis of epididymis epithelial function, which has a pivotal role in male fertility.

Androgenic regulation of beta-defensins in the mouse epididymis

BACKGROUND

The majority of beta-defensin family members are exclusively expressed in the epididymis, and some members have been shown to play essential roles in sperm maturation and fertility in rats, mice and humans. Therefore, beta-defensins are hypothesized to be potential targets for contraception and infertility diagnosis and treatment. Clarifying the regulatory mechanisms for the expression of these genes is necessary. Androgen/androgen receptor (AR) signaling plays an important regulatory role in epididymal structure and function. However, very little is known about the androgenic regulation on the production and secretion of the epididymal beta-defensins.

METHODS

The expression of beta-defensins was detected by quantitative RT-PCR. The androgen dependence of beta-defensins was determined by bilateral orchiectomy and androgen supplementation. The androgen response elements (AREs) in the promoters of beta-defensins were identified using the MatInspector software. The binding of AR to AREs was assayed by ChIP-PCR/qPCR.

RESULTS

We demonstrated that 23 mouse caput epididymal beta-defensins were differentially regulated by androgen/androgen receptor. Six genes, Defb18, 19, 20, 39, 41, and 42, showed full regulation by androgens. Ten genes, Defb15, 30, 34, 37, 40, 45, 51, 52, 22 and Spag11a, were partially regulated by androgens. Defb15, 18, 19, 20, 30, 34, 37, 39, 41, 42, 22 and Spag11a were associated with androgen receptor binding sites in their promoter or intronic regions, indicating direct regulation of AR. Six genes, Defb1, 12, 13, 29, 35, and spag11b/c, exhibited an androgen-independent expression pattern. One gene, Defb25, was highly dependent on testicular factors rather on androgens.

CONCLUSIONS

The present study provides novel insights into the mechanisms of androgen regulation on epididymal beta-defensins, enabling a better understanding of the function of beta-defensins in sperm maturation and fertility.

Androgens and mammalian male reproductive tract development

One of the main functions of androgen is in the sexually dimorphic development of the male reproductive tissues. During embryogenesis, androgen determines the morphogenesis of male specific organs, such as the epididymis, seminal vesicle, prostate and penis. Despite the critical function of androgens in masculinization, the downstream molecular mechanisms of androgen signaling are poorly understood. Tissue recombination experiments and tissue specific androgen receptor (AR) knockout mouse studies have revealed epithelial or mesenchymal specific androgen-AR signaling functions. These findings also indicate that epithelial-mesenchymal interactions are a key feature of AR specific activity, and paracrine growth factor action may mediate some of the effects of androgens. This review focuses on mouse models showing the interactions of androgen and growth factor pathways that promote the sexual differentiation of reproductive organs. Recent studies investigating context dependent AR target genes are also discussed. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Transcriptional regulation of the rat sperm-associated antigen 11e (Spag 11e) gene during endotoxin challenge

The lipopolysaccharide (LPS) inducible expression of antimicrobial proteins of the Sperm-Associated Antigen 11 (Spag11) family is dependent on nuclear factor-κB (NF-κB) activation and epigenetic factors. However, the regulatory mechanisms that govern their gene expression during endotoxin challenge are unknown. In this study, we demonstrate that the Spag11e gene upstream sequence contains binding sites for androgen receptor (AR), NF-κB, nuclear factor-1, E-twenty-six and activator protein 2. The role of these transcription factors in inducing Spag11e gene during LPS challenge was analysed by measuring luciferase activity in HEK cells transiently transfected with deletion constructs that lacked one or more of the binding sites. Deletion of AR-binding site resulted in loss of luciferase activity and no further decrease was observed when progressive deletions of the other transcription factor binding sites were made. Mutations in AR or NF-κB binding site resulted in loss of luciferase activity. Electrophoretic gel-mobility shift assays indicated that AR and NF-κB proteins bind to the synthesised radio-labelled oligomers used as probes and the mobility shifted when respective antibodies were added. Results of this study indicate the direct involvement of AR and NF-κB in LPS-induced Spag11e expression, thereby expanding our understanding of antimicrobial gene expression during endotoxin challenge.

Different effects of androgen on the expression of Fut1, Fut2, Fut4 and Fut9 in male mouse reproductive tract

The α-(1,2) fucosyltransferases (Fut1 and Fut2) and α-(1,3) fucosyltransferases (Fut4, Fut9) are responsible for the synthesis of Lewis X (LeX) and Lewis Y (LeY) conjugated to glycoproteins. We recently reported that these fucosyltransferases were differentially expressed in the reproductive tract of male mouse. Here, we studied the effect of androgen on fucosyltransferase expression through the use of mouse castration models. We found that Fut1 mRNA and Fut4 mRNA were upregulated, while Fut2 mRNA and Fut9 mRNA were downregulated by androgen in the caput epididymis. However, in the vas deferens and prostate, only Fut4 mRNA and Fut2 mRNA were respectively upregulated following exposure to androgen. In the seminal vesicle, all fucosyltransferases, with the exception of Fut9, were upregulated. We identified the androgen receptor binding sites (ARBSs) of Fut2, Fut4 and Fut9 in the caput epididymis. Luciferase assay for these ARBSs is able to provide an indication as to why Fut4 and Fut9 are differently expressed and regulated by androgen, although they catalyze the same α-(1,3) fucose linkage. Our study showed that androgen could differentially regulate the expression of these fucosyltransferases and provided an insight into the characteristic distribution of each fucosyltransferase responsible for LeX/LeY biosynthesis in the male reproductive tract.

A genome-wide analysis of open chromatin in human epididymis epithelial cells reveals candidate regulatory elements for genes coordinating epididymal function

The epithelium lining the epididymis has a pivotal role in ensuring a luminal environment that can support normal sperm maturation. Many of the individual genes that encode proteins involved in establishing the epididymal luminal fluid are well characterized. They include ion channels, ion exchangers, transporters, and solute carriers. However, the molecular mechanisms that coordinate expression of these genes and modulate their activities in response to biological stimuli are less well understood. To identify cis-regulatory elements for genes expressed in human epididymis epithelial cells, we generated genome-wide maps of open chromatin by DNase-seq. This analysis identified 33,542 epididymis-selective DNase I hypersensitive sites (DHS), which were not evident in five cell types of different lineages. Identification of genes with epididymis-selective DHS at their promoters revealed gene pathways that are active in immature epididymis epithelial cells. These include processes correlating with epithelial function and also others with specific roles in the epididymis, including retinol metabolism and ascorbate and aldarate metabolism. Peaks of epididymis-selective chromatin were seen in the androgen receptor gene and the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which has a critical role in regulating ion transport across the epididymis epithelium. In silico prediction of transcription factor binding sites that were overrepresented in epididymis-selective DHS identified epithelial transcription factors, including ELF5 and ELF3, the androgen receptor, Pax2, and Sox9, as components of epididymis transcriptional networks. Active genes, which are targets of each transcription factor, reveal important biological processes in the epididymis epithelium.

An androgen receptor-microrna-29a regulatory circuitry in mouse epididymis

MicroRNAs are involved in a number of cellular processes; thus, their deregulation is usually apt to the occurrence of diverse diseases. Previous studies indicate that abnormally up-regulated miR-29a is associated with several diseases, such as human acute myeloid leukemia and diabetes; therefore, the proper level of miR-29a is critical for homeostasis. Herein, we observed that miR-29a was repressed by androgen/androgen receptor signaling in mouse epididymis by targeting a conserved androgen response element located 8 kb upstream of miR-29b1a loci. It is well known that multiple regulatory programs often form a complicated network. Here, we found that miR-29a reversibly suppressed androgen receptor and its target genes by targeting IGF1 and p53 pathways. miR-29b1a-overexpressing transgenic mice displayed epididymis hypoplasia partially similar to the phenotype of those mice with an impaired androgen-androgen receptor signal system. Taken together, the results demonstrated that there is a regulatory circuitry between the androgen signaling pathway and miR-29a in mouse epididymis that may be vital for epididymal development and functions.

The impact of obesity on male reproduction: its biological significance

Since obesity and male subfertility have increased in parallel during the last decades, the hypothesis of an association between these two phenomena has been explored by several researchers. Although there is no consensus apparently obesity impacts men's reproductive potential by several mechanisms, like alterations on the hypothalamus-pituitary-testicular axis, modifications of spermatogenesis and semen quality and/or impairment of men's sexual health. This review intends to summarize the underlying bases of such alterations and propose new ones, without miscalculating their biological significance. Obesity is not rigorously related to subfertility; in addition, the existence of a genetic predisposition to obesity-linked sterility is currently under investigation. Nonetheless, the impact of obesity on male reproductive potential must be fully elucidated since the prevalence of obesity is increasing and consequently, the number of obese men with reduced fertility will also rise.

DNA demethylation-dependent AR recruitment and GATA factors drive Rhox5 homeobox gene transcription in the epididymis

Mammalian male fertility depends on the epididymis, a highly segmented organ that promotes sperm maturation and protects sperm from oxidative damage. Remarkably little is known about how gene expression is controlled in the epididymis. A candidate to regulate genes crucial for epididymal function is reproductive homeobox gene on X chromosome (RHOX)5, a homeobox transcription factor essential for optimal sperm motility that is expressed in the caput region of the epididymis. Here, we report the identification of factors that control Rhox5 gene expression in epididymal cells in a developmentally regulated and region-specific fashion. First, we identify GATA transcription factor-binding sites in the Rhox5 proximal promoter (Pp) necessary for Rhox5 expression in epididymal cells in vitro and in vivo. Adjacent to the GATA sites are androgen-response elements, which bind to the nuclear hormone receptor androgen receptor (AR), and are responsible for the AR-dependent expression of Rhox5 in epididymal cells. We provide evidence that AR is recruited to the Pp in a region-specific and developmentally regulated manner in the epididymis that is dictated not only by differential AR availability but differential methylation of the Pp. Site-specific methylation of the Pp cytosine and guanine separated by one phosphate, most of which overlap with androgen-response elements, inhibited both AR occupancy at the Pp and Pp-dependent transcription in caput epididymal cells. Together, our data support a model in which DNA methylation, AR, and GATA factors collaborate to dictate the unique developmental and region-specific expression pattern of the RHOX5 homeobox transcription factor in the caput epididymis, which in turn controls the expression of genes critical for promoting sperm motility and function.

Caveolin-1 and prostate cancer progression

Caveolin-1 was identified in the 1990s as a marker of aggressive prostate cancer. The caveolin-1 protein localizes to vesicular structures called caveolae and has been shown to bind and regulate many signaling proteins involved in oncogenesis. Caveolin-1 also has lipid binding properties and mediates aspects of cholesterol and fatty acid metabolism and can elicit biological responses in a paracrine manner when secreted. Caveolin-1 is also present in the serum of prostate cancer patients and circulating levels correlate with extent of disease. Current evidence indicates that increased expression of caveolin-1 in prostate adenocarcinoma cells and commensurate downregulation of the protein in prostate stroma, mediate progression to the castration-resistant phase of prostate cancer through diverse pathways. This chapter summarizes the current state of our understanding of the cellular and physiologic mechanisms in which caveolin-1 participates in the evolution of prostate cancer cell phenotypes.

Dephosphorylated NSSR1 is induced by androgen in mouse epididymis and phosphorylated NSSR1 is increased during sperm maturation

NSSR1 (Neural salient serine/arginine rich protein 1, alternatively SRp38) is a newly identified RNA splicing factor and predominantly expressed in neural tissues. Here, by Western blot analysis and immunofluorescent staining, we showed that the expression of dephosphorylated NSSR1 increased significantly during development of the caput epididymis. In adult mice, phosphorylated NSSR1 was mainly expressed in the apical side of epithelial cells, and dephosphorylated NSSR1 in caput epididymis was upregulated in a testosterone dependent manner. In addition, subcellular immunoreactive distribution of NSSR1 varied in different regions of the epididymis. With respect to the sperm, phosphorylated NSSR1 was detected in the mid-piece of the tail as well as the acrosome. Furthermore, NSSR1 was released from the sperm head during the capacitation and acrosome reaction. These findings for the first time provide the evidence for the potential roles of NSSR1 in sperm maturation and fertilization.

Cell autonomous role of PTEN in regulating castration-resistant prostate cancer growth

Alteration of the PTEN/PI3K pathway is associated with late-stage and castrate-resistant prostate cancer (CRPC). However, how PTEN loss is involved in CRPC development is not clear. Here, we show that castration-resistant growth is an intrinsic property of Pten null prostate cancer (CaP) cells, independent of cancer development stage. PTEN loss suppresses androgen-responsive gene expressions by modulating androgen receptor (AR) transcription factor activity. Conditional deletion of Ar in the epithelium promotes the proliferation of Pten null cancer cells, at least in part, by downregulating the androgen-responsive gene Fkbp5 and preventing PHLPP-mediated AKT inhibition. Our findings identify PI3K and AR pathway crosstalk as a mechanism of CRPC development, with potentially important implications for CaP etiology and therapy.

Essential roles of androgen signaling in Wolffian duct stabilization and epididymal cell differentiation

The epididymis is a male accessory organ and functions for sperm maturation and storage under the control of androgen. The development of the epididymis is also androgen dependent. The Wolffian duct (WD), anlagen of the epididymis, is formed in both male and female embryos; however, it is stabilized only in male embryos by testicular androgen. Androgen drives subsequent differentiation of the WD into the epididymis. Although the essential roles of androgen in WD masculinization and epididymal function have been established, little is known about cellular events regulated precisely by androgen signaling during these processes. It is also unclear whether androgen signaling, especially in the epithelia, has further function for epididymal epithelial cell differentiation. In this study we examined the cellular death and proliferation controlled by androgen signaling via the androgen receptor (AR) in WD stabilization. Analyses using AR knockout mice revealed that androgen signaling inhibits epithelial cell death in this process. Analysis of AP2α-Cre;AR(flox/Y) mice, in which AR function is deleted in the WD epithelium, revealed that epithelial AR is not required for the WD stabilization but is required for epithelial cell differentiation in the epididymis. Specifically, loss of epithelial AR significantly reduced expression of p63 that is essential for differentiation of basal cells in the epididymal epithelium. We also interrogated the possibility of regulation of the p63 gene (Trp63) by AR in vitro and found that p63 is a likely direct target of AR regulation.

Gene expression in the efferent ducts, epididymis, and vas deferens during embryonic development of the mouse

The tissues of the male reproductive tract are characterized by distinct morphologies, from highly coiled to un-coiled. Global gene expression profiles of efferent ducts, epididymis, and vas deferens were generated from embryonic day 14.5 to postnatal day 1 as tissue-specific morphologies emerge. Expression of homeobox genes, potential mediators of tissue-specific morphological development, was assessed. Twenty homeobox genes were identified as either tissue-enriched, developmentally regulated, or both. Additionally, ontology analysis demonstrated cell adhesion to be highly regulated along the length of the reproductive tract. Regulators of cell adhesion with variable expression between the three tissues were identified including Alcam, various cadherins, and multiple integrins. Immunofluorescence localization of the cell adhesion regulators POSTN and CDH2 demonstrated cell adhesion in the epithelium and mesenchyme of the epididymis may change throughout development. These results suggest cell adhesion may be modulated in a tissue-specific manner, playing an important role in establishing each tissue's final morphology.

Localization and androgen regulation of metastasis-associated protein 1 in mouse epididymis

BACKGROUND

Metastasis-associated protein 1 (MTA1), the founding member of the MTA family of genes, can modulate transcription by influencing the status of chromatin remodeling. Despite its strong correlation with the metastatic potential of cancer cells, MTA1 can also regulate crucial cellular pathways by modifying the acetylation status. We have previously reported the presence of MTA1/MTA1 in human and mouse testes, providing the evidence for its involvement in the regulation of testicular function during murine spermatogenesis. The objective of present study was to further assess the localization of MTA1 in mouse epididymis on both transcriptional and translational level, and then to explore whether MTA1 expression is regulated by androgens and postnatal epididymal development.

METHODOLOGY/PRINCIPAL FINDINGS

Mice were deprived of circulating androgen by bilaterally castration and were then supplemented with exogenous testosterone propionate for one week. MTA1 was immunolocalized in the epithelium of the entire epididymis with the maximal expression in the nuclei of principal cells and of clear cells in proximal region. Its expression decreased gradually after castration, whereas testosterone treatment could restore the expression, indicating that the expression of this gene is dependent on androgen. During postnatal development, the protein expression in the epididymis began to appear from day 7 to day 14, increased dramatically from postnatal day 28, and peaked at adulthood onwards, coinciding with both the well differentiated status of epididymis and the mature levels of circulating androgens. This region- and cell-specific pattern was also conservative in normal human epididymis.

CONCLUSIONS

Our data suggest that the expression of MTA1 protein could be regulated by androgen pathway and its expression level is closely associated with the postnatal development of the epididymis, giving rise to the possibility that this gene plays a potential role in sperm maturation and fertility.

Research resource: Genome-wide mapping of in vivo androgen receptor binding sites in mouse epididymis

Epididymal function depends on androgen signaling through the androgen receptor (AR), although most of the direct AR target genes in epididymis remain unknown. Here we globally mapped the AR binding regions in mouse caput epididymis in which AR is highly expressed. Chromatin immunoprecipitation sequencing indicated that AR bound selectively to 19,377 DNA regions, the majority of which were intergenic and intronic. Motif analysis showed that 94% of the AR binding regions harbored consensus androgen response elements enriched with multiple binding motifs that included nuclear factor 1 and activator protein 2 sites consistent with combinatorial regulation. Unexpectedly, AR binding regions showed limited conservation across species, regardless of whether the metric for conservation was based on local sequence similarity or the presence of consensus androgen response elements. Further analysis suggested the AR target genes are involved in diverse biological themes that include lipid metabolism and sperm maturation. Potential novel mechanisms of AR regulation were revealed at individual genes such as cysteine-rich secretory protein 1. The composite studies provide new insights into AR regulation under physiological conditions and a global resource of AR binding sites in a normal androgen-responsive tissue.

Estrogen, efferent ductules, and the epididymis

Estrogen's presence in the male reproductive system has been known for over 60 years, but its potential function in the epididymis remains an important area of investigation. Estrogen is synthesized by germ cells, producing a relatively high concentration in rete testis fluid. There are two estrogen receptors (ESR), the presence of which in the head of the epididymis is well documented and consistent between species; however, in other regions of the epididymis, their expression appears to be isotype, species, and cell specific. ESR1 is expressed constitutively in the epididymis; however, its presence is downregulated by high doses of estrogen, making the design of experiments complicated, as the phenotype of the Cyp19a1(-/-) mouse does not resemble that of the Esr1(-/-) mouse. Ligand-independent and DNA-binding Esr1 mutant models further demonstrate the complexity and importance of both signaling pathways in maintenance of efferent ductules and epididymis. Data now reveal the presence of not only classical nuclear receptors, but also cytoplasmic ESR and rapid responding membrane receptors; however, their importance in the epididymis remains undetermined. ESR1 regulates ion transport and water reabsorption in the efferent ducts and epididymis, and its regulation of other associated genes is continually being uncovered. In the male, some genes, such as Aqp9 and Slc9a3, contain both androgen and estrogen response elements and are dually regulated by these hormones. While estrogen pathways are a necessity for fertility in the male, future studies are needed to understand the interplay between androgens and estrogens in epididymal tissues, particularly in cell types that contain both receptors and their cofactors.

Identification of early response genes and pathway activated by androgens in the initial segment and caput regions of the regressed rat epididymis

To identify the initial response to androgens and estrogens in the orchidectomized, regressed epididymis, we determined the gene expression changes triggered by the administration of either of two metabolites of testosterone, 5alpha-dihydrotestosterone (DHT) or 17beta-estradiol (E2), in the regressed rat epididymis. Adult rats were orchidectomized and 8 d later implanted with either empty implants (control), DHT-filled-, or E2-filled-polydioxanone implants. Rats were euthanized 12 h, 1 d, and 7 d later, and RNA was extracted and probed on Rat230-2.0 Affymetrix arrays. Probe sets that respond to DHT or E2 were identified at early time points; although the expression of some was repressed, the expression of many others was either transiently or chronically elevated. Nerve growth factor receptor (Ngfr) and S100 calcium binding protein G (S100g) were two E2 up-regulated genes detected at 12 h. Among the genes that showed a dramatic early response to DHT were endothelin 1 (Edn1), bone morphogenetic protein 4 (Bmp4), and IGF binding protein 3 (Igfbp3), which were suppressed, and IGF-I (Igf1), which was induced. Genes that were up- or down-regulated by DHT were classified based on biological function. Using PathwayStudio 4.0, we identified genes that were linked and directly influenced either the expression or regulation of one another. Epidermal growth factor and IGF-I play an important role in the pathway due to their function in regulation and expression of many other genes. These results provide novel insights into the impact of androgen action on the expression of genes that are important for epididymal function.

Identification of cis-regulatory elements in the mammalian genome: the cREMaG database

Background

A growing number of gene expression-profiling datasets provides a reliable source of information about gene co-expression. In silico analyses of the properties shared among the promoters of co-expressed genes facilitates the identification of transcription factors (TFs) involved in the co-regulation of those genes. Our previous experience with microarray data led to the development of a database suitable for the examination of regulatory motifs in the promoters of co-expressed genes.

Methodology

We introduce the cREMaG (cis-Regulatory Elements in the Mammalian Genome) system designed for in silico studies of the promoter properties of co-regulated mammalian genes. The cREMaG system offers an analysis of data obtained from human, mouse, rat, bovine and canine gene expression-profiling studies. More than eight analysis parameters can be utilized in user-defined combinations. The selection of alternative transcription start sites and information about CpG islands are also available.

Conclusions

Using the cREMaG system, we successfully identified TFs mediating transcriptional responses in reference gene sets. The cREMaG system facilitates in silico studies of mammalian transcriptional gene regulation. The resource is freely available at http://www.cremag.org.

Comparative profiling of genes and miRNAs expressed in the newborn, young adult, and aged human epididymides

To understand roles of transcriptional factors and miRNAs in regulating gene expression in the epididymis from postnatal development through aging, systematic profiling of genes and miRNAs expressed in the newborn, young adult, and aged human epididymides was performed by cDNA array and miRNA array analysis, respectively. The newborn human epididymis expressed the fewest mRNAs but the largest number of miRNAs, whereas the adult and aged epididymides expressed the most mRNAs but the fewest miRNAs, a negative correlation between mRNAs and miRNA during aging. By integrative analysis, a set of miRNA targets were predicted based on the miRNA and cDNA arrays. In the newborn epididymis, 127 miRNAs were exclusively or preferentially expressed but only 3 and 2 miRNAs showed an age-enriched expression pattern in the adult and aged epididymides, respectively. This study provides a basic database as well as new insights and foundations for further studies on the complex regulation of gene expression in the epididymis.

Overweight and seminal quality: a study of 794 patients

OBJECTIVES

To evaluate sperm quality, levels of markers of epididymal and accessory gland function, and T in semen from men grouped according to their body mass index (BMI).

DESIGN

Blind prospective study.

SETTING

Andrology and reproduction laboratory in Cordoba, Argentina (2006-2007).

PATIENT(S)

Seven hundred ninety-four men.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

In semen samples, sperm quality (volume, density, motility, morphology, viability, hypoosmotic swell test, and nuclear maturity) and levels of neutral alpha-glucosidase, fructose, citric acid and T.

RESULT(S)

Multivariate analysis showed a negative association between BMI and motility, rapid motility and neutral alpha-glucosidase levels, and a positive association between BMI and seminal fructose levels. No associations were found among BMI and sperm concentration, the other parameters evaluated, or seminal T levels.

CONCLUSION(S)

Results found in our study support a deleterious effect of obesity on seminal quality, probably by alterations in the function of the epididymis (i.e., in epididymal maturation).

Transplanted XY germ cells produce spermatozoa in testes of XXY mice

XXY mouse has been characterized as an experimental model for men with Klinefelter's syndrome (XXY male phenotype). To test whether donor XY germ cells could proliferate and differentiate in the XXY testicular environment, donor testicular cells from adult (2-3 months old) and immature (10 days old) XY green fluorescence protein (GFP) transgenic mice were transplanted into the seminiferous tubules of adult (4-7 months old) and young (6 weeks old) XXY recipient mice respectively. Twelve weeks after transplantation, GFP positive spermatogonia were found in 21.74% (five out of 23) of adult XXY recipients who received adult donor cells. The GFP positive segments of seminiferous tubules were observed in 44.44% (four out of nine) young XXY recipients who received donor cells from 10 days old GFP mice. We found using immunohistochemistry and cell morphology that donor-derived GFP positive germ cells were spermatogonia, spermatocytes, round spermatids and spermatozoa in some of the seminiferous tubules of young XXY recipient mice. The results demonstrated that the donor XY germ cells were able to qualitatively complete spermatogenesis in some of the seminiferous tubules of XXY mice.

Regulation of gene expression by estrogen and testosterone in the proximal mouse reproductive tract

The role of estrogen and testosterone in the regulation of gene expression in the proximal reproductive tract is not completely understood. To address this question, mice were treated with testosterone or estradiol, and RNA from the efferent ducts and caput epididymides was processed and hybridized to Affymetrix M430 2.0 microarrays. Analysis of array output identified probe sets in each tissue with altered levels in hormone-treated versus control animals. Hormone treatment efficacy was confirmed by determination of serum hormone levels before and after treatment and by observed changes in transcript levels of previously reported hormone-responsive genes. Tissue-specific hormone sensitivity was observed with 2867 and 3197 probe sets changing significantly in the efferent ducts after estrogen and testosterone treatment, respectively. In the caput epididymidis, 117 and 268 probe sets changed after estrogen and testosterone treatment, respectively, demonstrating a greater response to hormone in the efferent ducts than in the caput epididymidis. Transcripts sharing similar profiles in the intact and hormone-treated animals compared with castrated controls were also identified. Ontology analysis of probe sets revealed that a significant number of hormone-regulated transcripts encode proteins associated with lipid metabolism, transcription, and steroid metabolism in both tissues. Real-time RT-PCR was used to confirm array data and to investigate other potential hormone-responsive regulators of proximal reproductive tract function. The results of this work reveal previously unknown responses to estrogen in the caput epididymidis and to testosterone in the efferent ducts, as well as tissue-specific hormone sensitivity in the proximal reproductive tract.

Differential testicular gene expression in seasonal fertility

Spermatogenesis is an essential precursor for successful sexual reproduction. Recently, there has been an expansion in the knowledge of the genes associated with particular stages of normal, physiological testicular development and pubertal activation. What has been lacking, however, is an understanding of those genes that are involved in specifically regulating sperm production, rather than in maturation and elaboration of the testis as an organ. By using the reversible (seasonal) fertility of the Syrian hamster as a model system, the authors sought to discover genes that are specifically involved in turning off sperm production and not involved in tissue specification and/or maturation. Using gene expression microarrays and in situ hybridization in hamsters and genetically infertile mice, the authors have identified a variety of known and novel factors involved in reversible, transcriptional, translational, and posttranslational control of testicular function, as well those involved in cell division and macromolecular metabolism. The novel genes uncovered could be potential targets for therapies against fertility disorders.

An epididymis-specific secretory protein HongrES1 critically regulates sperm capacitation and male fertility

Mammalian sperm capacitation is an essential prerequisite to fertilizion. Although progress had been made in understanding the physiology and biochemistry of capacitation, little is known about the potential roles of epididymal proteins during this process. Here we report that HongrES1, a new member of the SERPIN (serine proteinase inhibitor) family exclusively expressed in the rat cauda epididymis and up-regulated by androgen, is secreted into the lumen and covers the sperm head. Co-culture of caudal sperms with HongrES1 antibody in vitro resulted in a significant increase in the percentage of capacitated spermatozoa. Furthermore, the percentage of capacitated spermatozoa clearly increased in rats when HongrES1 was down-regulated by RNAi in vivo. Remarkably, knockdown of HongrES1 in vivo led to reduced fertility accompanied with deformed appearance of fetuses and pups. These results identify HongrES1 as a novel and critical molecule in the regulation of sperm capacitation and male fertility.

Severe subfertility in mice with androgen receptor inactivation in sex accessory organs but not in testis

Androgen action on sex accessory organs influences rodent fertility, but the mechanisms remain unclear and investigation is difficult without the ability to restrict androgen action in specific tissues. We used Cre-LoxP technology to generate male mice with prostate epithelial-specific androgen receptor deficiency (denoted PEARKO). In addition to prostate, these males have reduced androgen action due to tissue-selective androgen receptor inactivation in seminal vesicle, epididymis, and vas deferens, whereas the testis is unaffected. We find that fertility of PEARKO males was severely reduced, compared with littermates with prominent defects in copulatory plug formation, which were smaller, softer, and more friable than controls. Despite normal testis sperm production, sperm numbers were reduced in caput but increased in cauda epididymis, suggesting alterations in sperm epididymal transit kinetics associated with increased rate of spontaneous acrosome reaction and abnormal flagellar morphology in PEARKO cauda epididymal sperm. Whereas the quantitative in vitro fertilizing ability of PEARKO epididymal sperm was normal, fewer fertilized oocytes were flushed from the oviducts of females after natural mating with PEARKO males. These data show that sperm formed in mice with impaired androgen action restricted to accessory glands and epididymis are quantitatively normal in number and in vitro fertilizing function but that severe in vivo subfertility reflects other functions related to sperm transport and survival in female reproductive tract that determine fertility in vivo.