Sertoli cell tight junction dynamics: their regulation during spermatogenesis

Curcumin ameliorates aging-induced blood-testis barrier disruption by regulating AMPK/mTOR mediated autophagy

The blood-testis barrier (BTB) is composed of tight junctions (TJ) between adjacent Sertoli cells (SCs) and is crucial for sperm growth and development. Aging-induced TJ impairment is closely related to testicular dysfunction. Curcumin, a natural compound, has been widely demonstrated to have a wide range of pharmacological activities, but its regulatory effects on tight junction damage in the testis remain unclear. We here explored the effect of curcumin on TJ function and its underlying molecular mechanism by using D-galactose (D-gal)-induced mouse testis and mouse testicular SCs (TM4) aging models in vitro. In this study, D-gal increased the expression of aging-related proteins p16 and p21, whereas significantly decreased the expression of TJ proteins (ZO-1, Claudin-4, Claudin-7, and Occludin). In addition, curcumin restored the adverse effects of D-gal in the SCs. Autophagy is a degradation system for maintaining cell renewal and homeostasis. D-gal significantly decreased the autophagy level, whereas curcumin restored the effect of D-gal. Using chloroquine (CQ), an inhibitor of autophagy, and rapamycin (RAPA), an activator of autophagy, it was demonstrated that autophagy plays a key role in curcumin amelioration of TJ injury in testicular SCs. Further studies unveiled that autophagy activation was mediated through the AMPK/mTOR pathway. In conclusion, curcumin ameliorates aging-induced TJ damage through AMPK/mTOR signaling pathway-regulated autophagy. This study thus clearly identifies a novel action mechanism of curcumin in the treatment of age-related male reproductive disorders.

Quaternary ammonium compound exposure causes infertility by altering endocrine signaling and gametogenesis

Quaternary ammonium compounds (QACs) are common substances utilized in cleaners, ophthalmic solutions, swimming pool treatments, cosmetics, and other consumer goods. Previous studies have shown that QAC exposure causes infertility in both male and female mice. Based on these studies, we hypothesized that oral QAC exposure negatively impacts male and female reproduction through changes in physiologic and endocrine mechanisms rather than direct toxicity to gametes. Endocrine disruption was assessed by evaluating luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations in male and female mice exposed orally throughout gestation and lactation, and by changes in estrogen and progesterone in in orally exposed females throughout pregnancy. Sperm functionality and spermatogenesis were assessed by in vitro fertilization; while Sertoli cell homeostasis was evaluated by determining cellular metabolism, cell cycle progression and blood-testes barrier (BTB) permeability. QAC exposure decreased LH, and FSH concentrations in both males and females, and decreased progesterone and estrogen concentrations during pregnancy. QACs significantly decreased Sertoli cell metabolism at 0.0005 % ADBAC+DDAC well before disruption of the BTB at 0.01 %. Fertilization was not affected 24 h after exposure but was decreased after a 10 day rest period suggesting a disruption in spermatogenesis rather than direct toxicity to sperm. Lastly, QAC exposure altered Sertoli cell cycling with a G2/M cycle arrest. While the effect of QAC exposure on humans is unknown, implications from the in vivo and in vitro studies are concerning given the rise in infertility rates and increased reliance on assisted reproductive technologies along with ubiquitous exposure to QACs.

Spatial Transcriptomics Reveals the Temporal Architecture of the Seminiferous Epithelial Cycle and Precise Sertoli-Germ Synchronization

Spermatogenesis is characterized by the seminiferous epithelial cycle, a periodic pattern of germ cell differentiation with a wave-like progression along the length of seminiferous tubules. While key signaling and metabolic components of the cycle are known, the transcriptional changes across the cycle and the correlations between germ cell and somatic lineages remain undefined. Here, we use spatial transcriptomics via RNA SeqFISH+ to profile 2,638 genes in 216,090 cells in mouse testis and identify a periodic transcriptional pattern across tubules that precisely recapitulates the seminiferous epithelial cycle, enabling us to map cells to specific timepoints along the developmental cycle. Analyzing gene expression in somatic cells reveals that Sertoli cells exhibit a cyclic transcriptional profile closely synchronized with germ cell development while other somatic cells do not demonstrate such synchronization. Remarkably, in mouse testis with drug-induced ablation of germ cells, Sertoli cells independently maintain their cyclic transcriptional dynamics. By analyzing expression data, we identify an innate retinoic acid cycle, a network of transcription factors with cyclic activation, and signaling from germ cells that could interact with this network. Together, this work leverages spatial geometries for mapping the temporal dynamics and reveals a regulatory mechanism in spermatogenesis where Sertoli cells oscillate and coordinate with the cyclical progression of germ cell development.

Comprehensive analysis of differentially expressed mRNAs, circRNAs, and miRNAs and their ceRNA network in the testis of cattle-yak, yak, and cattle

Cattle-yak is a hybrid offspring resulting from the crossbreeding of yak and cattle, and it exhibits substantial heterosis in production performance. However, male sterility in cattle-yak remains a concern. Reports suggest that noncoding RNAs are involved in the regulation of spermatogenesis. Therefore, in this study, we comprehensively compared testicular transcription profiles among cattle, yak, and cattle-yak. Numerous differentially expressed genes (DEGs), differentially expressed circRNAs (DECs), and differentially expressed miRNAs (DEMs) were identified in the intersection of two comparison groups, namely cattle versus cattle-yak and yak versus cattle-yak, with the number of DEGs, DECs, and DEMs being 4968, 360, and 59, respectively. The DEGs in cattle-yaks, cattle, and yaks were mainly associated with spermatogenesis, male gamete generation, and sexual reproduction. Concurrently, GO and KEGG analyses indicated that DEC host genes and DEM source genes were involved in the regulation of spermatogenesis. The construction of a potential competing endogenous RNA network revealed that some differentially expressed noncoding RNAs may be involved in regulating the expression of genes related to testicular spermatogenesis, including miR-423-5p, miR-449b, miR-34b/c, and miR-15b, as well as previously unreported miR-6123 and miR-1306, along with various miRNA-circRNA interaction pairs. This study serves as a valuable reference for further investigations into the mechanisms underlying male sterility in cattle-yaks.

Mating-induced Ecdysone in the testis disrupts soma-germline contacts and stem cell cytokinesis

Germline maintenance relies on adult stem cells to continually replenish lost gametes over a lifetime and respond to external cues altering the demands on the tissue. Mating worsens germline homeostasis over time, yet a negative impact on stem cell behavior has not been explored. Using extended live imaging of the Drosophila testis stem cell niche, we find that short periods of mating in young males disrupts cytokinesis in germline stem cells (GSCs). This defect leads to failure of abscission, preventing release of differentiating cells from the niche. We find that GSC abscission failure is caused by increased Ecdysone hormone signaling induced upon mating, which leads to disrupted somatic encystment of the germline. Abscission failure is rescued by isolating males from females, but recurs with resumption of mating. Importantly, reiterative mating also leads to increased GSC loss, requiring increased restoration of stem cells via symmetric renewal and de-differentiation. Together, these results suggest a model whereby acute mating results in hormonal changes that negatively impact GSC cytokinesis but preserves the stem cell population.

Effects and mechanisms of endocrine disruptor bisphenol AF on male reproductive health: A mini review

Bisphenol AF (BPAF), an analogue of bisphenol A (BPA), is commonly found in manufacturing industries and known for its endocrine-disrupting properties. Despite potential similarities in adverse effects with BPA, limited toxicological data exist specifically for BPAF and its impact on male reproductive physiology. This mini-review aims to elucidate the influence of BPAF on the male reproductive system, focusing on estrogenic effects, effects on the hypothalamus-pituitary-gonad (HPG) axis, steroidogenesis, spermatogenesis, and transgenerational reproductive toxicity. Additionally, we outline the current insights into the potential mechanisms underlying BPAF-induced male reproductive disorders. BPAF exposure, either directly or maternally, has been associated with detrimental effects on male reproductive functions, including damage to the blood-testis barrier (BTB) structure, disruptions in steroidogenesis, testis dysfunction, decreased anogenital distance (AGD), and defects in sperm and semen quality. Mechanistically, altered gene expression in the HPG axis, deficits in the steroidogenesis pathway, activation of the aromatase pathway, cascade effects induced by reactive oxygen species (ROS), activation of ERK signaling, and immunological responses collectively contribute to the adverse effects of BPAF on the male reproductive system. Given the high prevalence of male reproductive issues and infertility, along with the widespread environmental distribution of bisphenols, this study provides valuable insights into the negative effects of BPAF. The findings underscore the importance of considering the safe use of this compound, urging further exploration and regulatory attention to decrease potential risks associated with BPAF exposure.

The effect of HYPE knock-out on the AMPylome of human OSU-CLL leukemia cells

In humans, AMPylation of cellular proteins is carried out by Huntingtin yeast-interacting protein E (HYPE), activated under conditions of endoplasmic reticulum stress, such as in cancer cells. Extracts of the human chronic lymphocytic leukemia cell line, OSU-CLL, were fractionated using immuno-precipitation with antibodies against adenosine-phosphate and then AMP-Tyr. The proteins isolated were modified with AMP, the 'AMPylome.' AMP-labelled peptides isolated from HYPE wild-type (WT) and HYPE knock-out (KO) cells were identified using tandem mass spectrometry. A total of 213 proteins were identified from WT cell extracts, while only 23 of these were pulled down from KO cells, consistent with the presence of another AMPylator, besides HYPE. The KO cells were more sensitive to fludarabine nucleoside (2-FaraA) than WT cells. Ingenuity Pathway Analysis of the AMPylated proteins identified in WT cells clustered actin binding proteins of the cytoskeleton, and proteins of the RHO GTPase pathway that would jointly stimulate cell proliferation.

Mating-induced ecdysone in the testis disrupts soma-germline contacts and stem cell cytokinesis

Germline maintenance relies on adult stem cells to continually replenish lost gametes over a lifetime and respond to external cues altering the demands on the tissue. Mating worsens germline homeostasis over time, yet a negative impact on stem cell behavior has not been explored. Using extended live imaging of the Drosophila testis stem cell niche, we find that short periods of mating in young males disrupts cytokinesis in germline stem cells (GSCs). This defect leads to failure of abscission, preventing release of differentiating cells from the niche. We find that GSC abscission failure is caused by increased ecdysone hormone signaling induced upon mating, which leads to disrupted somatic encystment of the germline. Abscission failure is rescued by isolating males from females but recurs with resumption of mating. Importantly, reiterative mating also leads to increased GSC loss, requiring increased restoration of stem cells via symmetric renewal and de-differentiation. Together, these results suggest a model whereby acute mating results in hormonal changes that negatively impact GSC cytokinesis but preserves the stem cell population.

Adverse Effects of Prenatal Exposure to Oxidized Black Carbon Particles on the Reproductive System of Male Mice

Ambient black carbon (BC), a main constituent of atmospheric particulate matter (PM), is a primary particle that is mainly generated by the incomplete combustion of fossil fuel and biomass burning. BC has been identified as a potential health risk via exposure. However, the adverse effects of exposure to BC on the male reproductive system remain unclear. In the present study, we explored the effects of maternal exposure to oxidized black carbon (OBC) during pregnancy on testicular development and steroid synthesis in male offspring. Pregnant mice were exposed to OBC (467 μg/kg BW) or nanopure water (as control) by intratracheal instillation from gestation day (GD) 4 to GD 16.5 (every other day). We examined the testicular histology, daily sperm production, serum testosterone, and mRNA expression of hormone synthesis process-related factors of male offspring at postnatal day (PND) 35 and PND 84. Histological examinations exhibited abnormal seminiferous tubules with degenerative changes and low cellular adhesion in testes of OBC-exposed mice at PND 35 and PND 84. Consistent with the decrease in daily sperm production, the serum testosterone level of male offspring of OBC-exposed mice also decreased significantly. Correspondingly, mRNA expression levels of hormone-synthesis-related genes (i.e., StAR, P450scc, P450c17, and 17β-HSD) were markedly down-regulated in male offspring of PND 35 and PND 84, respectively. In brief, these results suggest that prenatal exposure has detrimental effects on mouse spermatogenesis in adult offspring.

What do we know about blood-testis barrier? current understanding of its structure and physiology

Blood-testis barrier (BTB) creates a particular compartment in the seminiferous epithelium. Contacting Sertoli cell-Sertoli cell plasma membranes possess specialized junction proteins which present a complex dynamic of formation and dismantling. Thus, these specialized structures facilitate germ cell movement across the BTB. Junctions are constantly rearranged during spermatogenesis while the BTB preserves its barrier function. Imaging methods are essential to studying the dynamic of this sophisticated structure in order to understand its functional morphology. Isolated Sertoli cell cultures cannot represent the multiple interactions of the seminiferous epithelium and in situ studies became a fundamental approach to analyze BTB dynamics. In this review, we discuss the contributions of high-resolution microscopy studies to enlarge the body of morphofunctional data to understand the biology of the BTB as a dynamic structure. The first morphological evidence of the BTB was based on a fine structure of the junctions, which was resolved with Transmission Electron Microscopy. The use of conventional Fluorescent Light Microscopy to examine labelled molecules emerged as a fundamental technique for elucidating the precise protein localization at the BTB. Then laser-scanning confocal microscopy allowed the study of three-dimensional structures and complexes at the seminiferous epithelium. Several junction proteins, like the transmembrane, scaffold and signaling proteins, were identified in the testis using traditional animal models. BTB morphology was analyzed in different physiological conditions as the spermatocyte movement during meiosis, testis development, and seasonal spermatogenesis, but also structural elements, proteins, and BTB permeability were studied. Under pathological, pharmacological, or pollutant/toxic conditions, there are significant studies that provide high-resolution images which help to understand the dynamic of the BTB. Notwithstanding the advances, further research using new technologies is required to gain information on the BTB. Super-resolution light microscopy is needed to provide new research with high-quality images of targeted molecules at a nanometer-scale resolution. Finally, we highlight research areas that warrant future studies, pinpointing new microscopy approaches and helping to improve our ability to understand this barrier complexity.

Curcumin Ameliorates Age-Induced Tight Junction Impaired in Porcine Sertoli Cells by Inactivating the NLRP3 Inflammasome through the AMPK/SIRT3/SOD2/mtROS Signaling Pathway

Blood-testis barrier (BTB) made of concomitant junction apparatus between Sertoli cells (SCs) is crucial for spermatogenesis. The tight junction (TJ) function is impaired in SCs with age, exhibiting an intimate relationship to testicular dysfunction induced by age. In this study, compared with those in young boars, TJ proteins (i.e., Occludin, ZO-1, and plus Claudin-11) were discovered to have reduced expressions in testes, and spermatogenesis ability declined in old boars. An in vitro age model for D-gal-treated porcine SCs was established, the performance of Curcumin as a natural antioxidant and anti-inflammatory compound in affecting the TJ function of SCs was appraised, and related molecular mechanisms were exploited. The results manifested that 40 g/L D-gal downregulated ZO-1, Claudin-11, and Occludin in terms of the expression in SCs, whereas Curcumin restored such expressions in D-gal-treated SCs. Using the AMPK and SIRT3 inhibiters demonstrated that activation of the AMPK/SIRT3 pathway was associated with Curcumin, which not only rescued the expression of ZO-1, Occludin, Claudin-11, and SOD2 but also inhibited the production of mtROS and ROS and the activation of NLRP3 inflammasome and release of IL-1β in D-gal-treated SCs. Furthermore, with mtROS scavenger (mito-TEMPO), NLRP3 inhibitor (MCC950) plus IL-1Ra treatment ameliorated D-gal-caused TJ protein decline in SCs. In vivo data also showed that Curcumin alleviated TJ impairment in murine testes, improved D-gal-triggered spermatogenesis ability, and inactivated the NLRP3 inflammasome by virtue of the AMPK/SIRT3/mtROS/SOD2 signal transduction pathway. Given the above findings, a novel mechanism where Curcumin modulates BTB function to improve spermatogenesis ability in age-related male reproductive disorder is characterized.

The regulatory role of BMP4 in testicular Sertoli cells of Tibetan sheep

This study aimed to determine the regulatory mechanism of bone morphogenetic protein 4 (BMP4) gene in the testes of Tibetan sheep and its role in the blood-testis barrier (BTB). First, we cloned BMP4 gene for bioinformatics analysis, and detected the mRNA and protein expression levels of BMP4 in the testes of Tibetan sheep pre-puberty (3-mo-old), during sexual maturity (1-yr-old), and in adulthood (3-yr-old) by qRT-PCR and Western blot. In addition, the subcellular localization of BMP4 was analyzed by immunohistochemical staining. Next, BMP4 overexpression and silencing vectors were constructed and transfected into primary Sertoli cells (SCs) to promote and inhibit the proliferation of BMP4, respectively. Then, CCK-8 was used to detect the proliferation effect of SCs. The expression of BMP4 and downstream genes, pathway receptors, tight junction-related proteins, and cell proliferation and apoptosis-related genes in SCs were studied using qRT-PCR and Western blot. The results revealed that the relative expression of BMP4 mRNA and protein in testicular tissues of 1Y group and 3Y group was dramatically higher than that of 3M group (P < 0.01), and BMP4 protein is mainly located in SCs and Leydig cells at different development stages. The CDS region of the Tibetan sheep BMP4 gene was 1,229 bp. CCK-8 results demonstrated that the proliferation rate of BMP4 was significantly increased in the overexpression group (pc-DNA-3.1(+)-BMP4; P < 0.05). In addition, the mRNA and protein expressions of SMAD5, BMPR1A, and BMPR1B and tight junction-related proteins Claudin11, Occludin, and ZO1 were significantly increased (P < 0.05). The mRNA expression of cell proliferation-related gene Bcl2 was significantly enhanced (P < 0.05), and the expression of GDNF was enhanced (P > 0.05). The mRNA expression of apoptosis-related genes Caspase3 and Bax decreased significantly (P < 0.05), while the mRNA expression of cell cycle-related genes CyclinA2 and CDK2 increased significantly (P < 0.05). It is worth noting that the opposite results were observed after transfection with si-BMP4. In summary, what should be clear from the results reported here is that BMP4 affects testicular development by regulating the Sertoli cells and BTB, thereby modulating the spermatogenesis of Tibetan sheep.

Canonical Wnt Signaling Promotes Formation of Somatic Permeability Barrier for Proper Germ Cell Differentiation

Morphogen-mediated signaling is critical for proper organ development and stem cell function, and well-characterized mechanisms spatiotemporally limit the expression of ligands, receptors, and ligand-binding cell-surface glypicans. Here, we show that in the developing Drosophila ovary, canonical Wnt signaling promotes the formation of somatic escort cells (ECs) and their protrusions, which establish a physical permeability barrier to define morphogen territories for proper germ cell differentiation. The protrusions shield germ cells from Dpp and Wingless morphogens produced by the germline stem cell (GSC) niche and normally only received by GSCs. Genetic disruption of EC protrusions allows GSC progeny to also receive Dpp and Wingless, which subsequently disrupt germ cell differentiation. Our results reveal a role for canonical Wnt signaling in specifying the ovarian somatic cells necessary for germ cell differentiation. Additionally, we demonstrate the morphogen-limiting function of this physical permeability barrier, which may be a common mechanism in other organs across species.

Involvement of TauT/SLC6A6 in Taurine Transport at the Blood-Testis Barrier

Taurine transport was investigated at the blood–testis barrier (BTB) formed by Sertoli cells. An integration plot analysis of mice showed the apparent influx permeability clearance of [³H]taurine (27.7 μL/(min·g testis)), which was much higher than that of a non-permeable paracellular marker, suggesting blood-to-testis transport of taurine, which may involve a facilitative taurine transport system at the BTB. A mouse Sertoli cell line, TM4 cells, showed temperature- and concentration-dependent [³H]taurine uptake with a K_m of 13.5 μM, suggesting that the influx transport of taurine at the BTB involves a carrier-mediated process. [³H]Taurine uptake by TM4 cells was significantly reduced by the substrates of taurine transporter (TauT/SLC6A6), such as β-alanine, hypotaurine, γ-aminobutyric acid (GABA), and guanidinoacetic acid (GAA), with no significant effect shown by L-alanine, probenecid, and L-leucine. In addition, the concentration-dependent inhibition of [³H]taurine uptake revealed an IC₅₀ of 378 μM for GABA. Protein expression of TauT in the testis, seminiferous tubules, and TM4 cells was confirmed by Western blot analysis and immunohistochemistry by means of anti-TauT antibodies, and knockdown of TauT showed significantly decreased [³H]taurine uptake by TM4 cells. These results suggest the involvement of TauT in the transport of taurine at the BTB.

Expression Analysis of Circular RNAs in Young and Sexually Mature Boar Testes

Simple Summary

Circular RNAs are novel long non-coding RNA involved in the regulation of gene expression. Recently, the expression of circRNAs was characterized in testes of humans and bulls. However, the profiling of circRNAs and their potential biological functions in boar testicular development are yet to be known. In this study we characterized expression and biological roles of circRNAs in piglet (30 d) and adult (210 d) boar testes by high-throughput sequencing. We identified a large number of circRNAs during testicular development, of which 2326 circRNAs exhibited a significantly differential expression. Gene ontology analysis revealed that these differential expressed circRNAs might be involved in regulating spermatogenesis and hormone biosynthesis. Overall, the results indicate that circRNAs are abundantly expressed in boar testes and exhibit dynamic changes during testicular development. These findings will enable the provision of potential molecular markers for both breeding of elite boars and evaluating developmental status of boar testes.

Abstract

Testicular development is critical for male animals’ reproduction and is tightly regulated by epigenetic factors. Circular RNAs (circRNAs) were recently identified in the testes of humans and bulls. However, the expression profile of circRNAs and their potential biological functions in boar testicular development remain unclear. We identified 34,521 and 31,803 circRNAs in piglet (30 d) and adult (210 d) boar testes by high-throughput sequencing, respectively. Bioinformatics analysis revealed that these circRNAs are widely distributed on autosomes and sex chromosomes. Some of the host genes can generate multiple circRNAs. A total of 2326 differentially expressed circRNAs (DECs) derived from 1526 host genes was found in testicular development, of which 1003 circRNAs were up-regulated in adult boar testes and 1323 circRNAs were down-regulated. Furthermore, gene ontology analysis of host genes of DECs revealed that these circRNAs are mainly involved in regulating spermatogenesis, cilia motility, and hormone biosynthesis. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the DECs are markedly enriched to stem cell pluripotency regulation, tight junctions, adhesion junctions, and cAMP signaling pathway. These results indicate that circRNAs are abundantly expressed in boar testes and exhibit dynamic changes during testicular development.

Evaluation of testicular toxicity upon fetal exposure to bisphenol A using an organ culture method

Humans are exposed to a multitude of endocrine disruptor chemicals (EDCs) that can interfere with the action of endogenous hormones and the normal development of reproductive organs. Bisphenol A (BPA) is one of the most common EDCs found in the environment. Here, we evaluated BPA toxicity on fetal testes using an in vitro organ culture system. Mouse fetal testes sampled at 15.5 days post coitus were cultured in a medium containing BPA for 5 days. The number of germ cells was reduced by BPA treatment, whereas the number of Sertoli cells was slightly increased by BPA at the highest dose (100 μM). Consistently, BPA treatment reduced the protein and gene expression levels of germ cell markers, but it increased the expression levels of Sertoli cell markers. The expression levels of fetal Leydig cell markers such as Cyp11a1, Thbs2, Cyp17a1, and Pdgf-α were significantly increased, whereas those of adult Leydig cell markers such as Hsd17b3, Ptgds, Sult1e1, Vcam1, and Hsd11b1 were decreased in the testes exposed to BPA. Generally, Notch signaling restricts Leydig cell differentiation from progenitor cells during fetal testis development. The expression levels of Notch1, Notch2, Notch3, Hes1, Ptch1, Jag1, Jag2, c-Myc, Hey1, and Hey2, which are involved in Notch signaling, were markedly higher in BPA-treated fetal testes than in the controls, indicating that BPA interrupts fetal Leydig cell development. BPA also disrupted steroidogenesis in the fetal testis organ culture system. In conclusion, our study showed that BPA inhibits fetal germ cell growth, Leydig cell development, and steroidogenesis.

Mutations in non-muscle myosin 2A disrupt the actomyosin cytoskeleton in Sertoli cells and cause male infertility

Mutations in non-muscle myosin 2A (NM2A) encompass a wide spectrum of anomalies collectively known as MYH9-Related Disease (MYH9-RD) in humans that can include macrothrombocytopenia, glomerulosclerosis, deafness, and cataracts. We previously created mouse models of the three mutations most frequently found in humans: R702C, D1424N, and E1841K. While homozygous R702C and D1424N mutations are embryonic lethal, we found homozygous mutant E1841K mice to be viable. However the homozygous male, but not female, mice were infertile. Here, we report that these mice have reduced testis size and defects in actin-associated junctions in Sertoli cells, resulting in inability to form the blood-testis barrier and premature germ cell loss. Moreover, compound double heterozygous (R702C/E1841K and D1424/E1841K) males show the same abnormalities in testes as E1841K homozygous males. Conditional ablation of either NM2A or NM2B alone in Sertoli cells has no effect on fertility and testis size, however deletion of both NM2A and NM2B in Sertoli cells results in infertility. Isolation of mutant E1841K Sertoli cells reveals decreased NM2A and F-actin colocalization and thicker NM2A filaments. Furthermore, A^E1841K/A^E1841K and double knockout Sertoli cells demonstrate microtubule disorganization and increased tubulin acetylation, suggesting defects in the microtubule cytoskeleton. Together, these results demonstrate that NM2A and 2B paralogs play redundant roles in Sertoli cells and are essential for testes development and normal fertility.

Novel targets identified by integrated proteomic and phosphoproteomic analysis in spermatogenesis of swamp buffalo (Bubalus bubalis)

To understand mechanisms of spermatogenesis, the proteome and the phosphoproteome in prepubertal and pubertal swamp buffalo (Bubalus bubalis) testes were analyzed using tandem mass tag (TMT) coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS). In prepubertal testes, 80 proteins were overexpressed, 148 proteins were underexpressed, and 139 and 142 protein sites had higher and lower phosphorylation, respectively, compared to the levels in pubertal testes. Several of these proteins were associated with reproductive processes such as sexual reproduction, spermatogenesis, fertilization, and spermatid development. In particular, outer dense fiber protein 1 (ODF1), protein maelstrom homolog (MAEL), actin-like protein 7B (ACTL7B), tyrosine-(Y)-phosphorylation regulated (CABYR), and tripartite motif containing 36 (TRIM36) were upregulated with age at both the proteome and phosphoproteome levels. Combining proteome and phosphoproteome analysis can be effectively applied to study the protein/phosphorylation patterns of buffalo testes. These data provide new regulatory candidates and evidence for a complex network in spermatogenesis in buffalo testes, and serve as an important resource for exploring the physiological mechanism of spermatogenesis in mammals.

Excessive unilateral proliferation of spermatogonia in a patient with non-obstructive azoospermia - adverse effect of clomiphene citrate pre-treatment?

Background

Clomiphene citrate has been proposed as pre-treatment for infertile men with non-obstructive, testicular azoospermia (NOA) before surgery for testicular sperm extraction (TESE), especially when serum testosterone is low.

Case presentation

Here, we report on a 33-year old azoospermic patient with a previous history of repeated "fresh" TESE and clomiphene citrate therapy (50 mg/day over 6 months) before undergoing microscopically assisted, bilateral testicular biopsy. Comprehensive histological and immunohistochemical work-up revealed a heterogeneous spermatogenic arrest at the level of spermatogonia or primary spermatocytes, with focally preserved spermatogenesis up to elongated spermatids in the right testis. In the left testis, the majority of tubules (> 70%) showed no tubular lumen or regular seminiferous epithelium but a great number of spermatogonia-like cells. These cells proved to be normally differentiated spermatogonia (positive for melanoma associated antigen 4 (MAGEA4), negative for placental alkaline phosphatase (PlAP)) with increased proliferative activity (positive for proliferating cell nuclear antigen (PCNA)) and a slightly higher rate of apoptotic cells. When compared to a tissue control with normal spermatogenesis, expression of sex hormone receptors androgen receptor (AR), estrogen receptor (ER) alpha, and G-protein coupled estrogen receptor 1 (GPER1) was not altered in patient samples. Sertoli cells appeared to be mature (positive for vimentin, negative for cytokeratin 18), whereas the expression of zona occludens protein 1 (ZO-1), claudin 11, and connexin 43 was absent or dislocated in the tubules with abundance of spermatogonia.

Conclusion

This result suggests that formation of the blood-testis barrier is disturbed in affected tubules. To our knowledge this is the first observation of excessive, non-malignant proliferation of spermatogonia in a NOA patient. Although underlying molecular mechanisms remain to be elucidated, we hypothesize that the unusual pathology was triggered by the high-dose clomiphene citrate treatment preceding testicular biopsy.

Deoxynivalenol induced spermatogenesis disorder by blood-testis barrier disruption associated with testosterone deficiency and inflammation in mice

Deoxynivalenol (DON) is an unavoidable cereal crops contaminants and environmental pollutants, which seriously threated the health of human and animal. DON has been reported to exert significant toxicity effects on spermatogenesis, but the underlying mechanisms remain largely inconclusive. The blood-testis barrier (BTB) provides a specialized biochemical microenvironment for maintaining spermatogenesis. Thus, we hypothesized that DON could impair BTB and lead to spermatogenesis disorder. To confirm this hypothesis, sixty male mice were intragastrically administered with 0, 1.2, 2.4 and 4.8 mg/kg body weight DON for 28 days, and several important observations were obtained in present study. First, we found that DON induced spermatogenesis disorder, reflected by the declines of sperm concentration and quality, sperm ultrastructural damage as well as seminiferous tubular damage. Then, we proved that DON induced BTB disruption as well as decreased the expressions of BTB junction proteins, including Occludin, Connexin 43 and N-cadherin. Finally, the present study showed that DON induced inflammation and inhibited T biosynthesis in testis of mice. These results revealed that DON induced spermatogenesis disorder by BTB disruption associated with testosterone deficiency and inflammation in mice, which shed a new light on the potential mechanisms of reproductive toxicity induced by DON.

New perspectives on PPAR, VDR and FXRα as new actors in testicular pathophysiology

The incidence of reproductive disorders is constantly increasing and affects 15% of couples, with male's abnormalities diagnosed in almost half of the cases. The male gonads exert two major functions of the testis with the productions of gametes (exocrine function) and of sexual hormones (endocrine function). In the last decades, next to steroid receptors such as estrogen and androgen receptors, the involvement of other members of the nuclear receptor superfamily have been described such as Steroidogenic factor-1 (SF-1), Nerve growth factor IB (NGFIB), Liver-X-Receptorα (LXRα) and Dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1 (DAX-1). The purpose of this review is to highlight the emerging roles of some members of the nuclear receptor superfamily among which the vitamin-D Receptor (VDR), Peroxisome Proliferator-Activated Receptor (PPAR), Farnesoid-X-Receptor-α (FXRα). We discuss how these receptors could participate to explain male fertility disorders; and their potential to be use as biomarkers or therapeutic targets for management of fertility disorders.

Methyl parathion causes genetic damage in sperm and disrupts the permeability of the blood-testis barrier by an oxidant mechanism in mice

Methyl parathion (Me-Pa) is an extremely toxic organophosphorus pesticide still used in developing countries. It has been associated with decreased sperm function and fertility and with oxidative and DNA damage. The blood-testis barrier (BTB) is a structure formed by tight junction (TJ) proteins in Sertoli cells and has a critical role in spermatogenesis. We assessed the effect of repeated doses of Me-Pa (3-12 mg/kg/day for 5 days, i.p.) on sperm quality, lipid oxidation, DNA integrity, and BTB permeability in adult male mice and explored oxidation as a mechanism of toxicity. Me-Pa caused dose-dependent effects on sperm quality, lipoperoxidation, and DNA integrity. Testis histology results showed the disruption of spermatogenesis progression and atrophy of seminiferous tubules. The pesticide opened the BTB, as evidenced by the presence of a biotin tracer in the adluminal compartment of the seminiferous tubules. This effect was not observed after 45 days of exposure when a spermatogenic cycle had completed. The coadministration of the antioxidant α-tocopherol (50 mg/kg/day for 5 days, oral) prevented the effects of Me-Pa on sperm quality, DNA and the BTB, indicating the importance of oxidative stress in the damage generated by Me-Pa. As evidenced by immunochemistry, no changes were found in the localization of the TJ proteins of the BTB, although oxidation (carbonylation) of total proteins in testis homogenates was detected. Our results show that Me-Pa disturbs the BTB and that oxidation is involved in the observed toxic effects on sperm cells.

The impact of thyroid diseases starting from birth on reproductive function

The aim of this review is to provide relevant information regarding the impact of thyroid disease, starting from birth and mainly concerning hyperthyroidism and hypothyroidism, on reproduction. Hyperthyroidism occurs much less commonly in children than hypothyroidism, with Graves' disease (GD) being the most common cause of thyrotoxicosis in children. Children born with neonatal GD have no defects in the reproductive system that could be related to hyperthyroidism. Current treatment options include antithyroid drugs (ATD), surgery, and radioactive iodine (RAI). In males, normal thyroid function seems important, at least in some parameters, for maintenance of semen quality via genomic or non-genomic mechanisms, either by locally acting on Sertoli cells, Leydig cells, or germ cells, or by affecting crosstalk between the HPT axis and the HPG axis. Sexual behavior may also be affected in thyroxic men, although many of these patients may have normal free testosterone levels. In women, menstrual irregularities are the most common reproduction-related symptoms in thyrotoxicosis, while this disorder is also associated with reduced fertility, although most women remain ovulatory. An increase in sex hormone-binding globulin (SHBG) and androgens, thyroid autoimmunity, and an impact on uterine oxidative stress are the main pathophysiological mechanisms which may influence female fertility. Thyroid hormones are responsible for normal growth and development during pre- and postnatal life, congenital hypothyroidism (CH) being the most common cause of neonatal thyroid disorders, affecting about one newborn infant in 3500. The reproductive tract appears to develop normally in cretins. Today, CH-screening programs allow for early identification and treatment, and, as a result, affected children now achieve normal or near-normal development. Hypothyroidism in males is associated with decreased libido or impotence. Although little is currently known about the effects of hypothyroidism on spermatogenesis and fertility, it has been established that sperm morphology and motility are mainly affected. In women of reproductive age, hypothyroidism results in changes in cycle length and amount of bleeding. Moreover, a negative effect on fertility and higher miscarriage rates has also been described.

Blood Testis Barrier and Somatic Cells Impairment in a Series of 35 Adult Klinefelter Syndrome Patients

Klinefelter Syndrome (KS) is the most common genetic cause of infertility in men. Degeneration of the testicular tissue starts in utero and accelerates at puberty with hyalinisation of seminiferous tubules, spermatogonia apoptosis and germ cell maturation arrest. Therefore, fertility preservation in young KS boys has been proposed, although this measure is still debated due to insufficient knowledge of the pathophysiology of the disease. To better understand the underlying mechanisms of testicular failure and germ cell loss, we analysed functional and morphological alterations in the somatic compartment of KS testis, i.e., Sertoli cells, including the blood-testis barrier (BTB) and Leydig cells (LC). We compared three populations: 35 KS 47,XXY non-mosaic patients, 28 Sertoli-cell-only (SCO) syndrome patients and 9 patients with normal spermatogenesis. In KS patients the expression of BTB proteins connexin-43 and claudin-11 assessed with a semi-quantitative scoring system appeared significantly reduced with a disorganised pattern. A significant reduction in seminiferous tubules expressing androgen receptors (AR) was observed in KS compared to normal spermatogenesis controls. INSL3 expression, a marker of LC maturation, was also significantly reduced in KS compared to patients with normal spermatogenesis or SCO. Hence, the somatic compartment impairment in KS could be involved in degeneration of seminiferous tubules.

Changes in sperm quality and testicular structure in a rat model of type 1 diabetes

Background

Chronic hyperglycemia is a characteristic of diabetes mellitus (DM). Long-lasting hyperglycemia can generate oxidative stress and reactive oxygen species. The effect of this condition on sperm quality and spermatogenesis leads to male infertility and reproductive dysfunction.

Objectives

To investigate changes in sperm quality, morphology of testicular structure, and stage of development of seminiferous tubules in a streptozotocin (STZ)-induced rat model of type 1 DM.

Methods

We divided 15 male Sprague Dawley rats into 2 groups. DM was induced in 7 rats using STZ (60 mg/kg intraperitoneally), while the other 8 were treated with citrate buffer as a vehicle control group. Rat semen was collected for quality measurements including motility, normal morphology, and concentration. Morphological changes in testicular structure and stage of development of seminiferous tubules were investigated by histology with hematoxylin and eosin (HE) staining.

Results

Significant decreases in all parameters of sperm quality and testicular weight were found in rats with induced DM. Moreover, abnormal morphology of seminiferous tubules including separation of the germinal epithelium, vacuolization, luminal sloughing of germ cells, and tubular atrophy was increased significantly in these rats, while the proportion of their seminiferous tubules at an early stage of development was significantly higher, but was dramatically decreased in the late stage of development when compared with that in vehicle-treated control rats.

Conclusions

DM has adverse effects on sperm quality, testicular structure, and development of seminiferous tubules. These findings may reflect the male infertility and reproductive dysfunction seen in patients with type 1 DM.

Investigation of betaine as a novel psychotherapeutic for schizophrenia

Background

Betaine is known to act against various biological stresses and its levels were reported to be decreased in schizophrenia patients. We aimed to test the role of betaine in schizophrenia pathophysiology, and to evaluate its potential as a novel psychotherapeutic.

Methods

Using Chdh (a gene for betaine synthesis)-deficient mice and betaine-supplemented inbred mice, we assessed the role of betaine in psychiatric pathophysiology, and its potential as a novel psychotherapeutic, by leveraging metabolomics, behavioral-, transcriptomics and DNA methylation analyses.

Findings

The Chdh-deficient mice revealed remnants of psychiatric behaviors along with schizophrenia-related molecular perturbations in the brain. Betaine supplementation elicited genetic background-dependent improvement in cognitive performance, and suppressed methamphetamine (MAP)-induced behavioral sensitization. Furthermore, betaine rectified the altered antioxidative and proinflammatory responses induced by MAP and in vitro phencyclidine (PCP) treatments. Betaine also showed a prophylactic effect on behavioral abnormality induced by PCP. Notably, betaine levels were decreased in the postmortem brains from schizophrenia, and a coexisting elevated carbonyl stress, a form of oxidative stress, demarcated a subset of schizophrenia with “betaine deficit-oxidative stress pathology”. We revealed the decrease of betaine levels in glyoxylase 1 (GLO1)-deficient hiPSCs, which shows elevated carbonyl stress, and the efficacy of betaine in alleviating it, thus supporting a causal link between betaine and oxidative stress conditions. Furthermore, a CHDH variant, rs35518479, was identified as a cis-expression quantitative trait locus (QTL) for CHDH expression in postmortem brains from schizophrenia, allowing genotype-based stratification of schizophrenia patients for betaine efficacy.

Interpretation

The present study revealed the role of betaine in psychiatric pathophysiology and underscores the potential benefit of betaine in a subset of schizophrenia.

Fund

This study was supported by the Strategic Research Program for Brain Sciences from AMED (Japan Agency for Medical Research and Development) under Grant Numbers JP18dm0107083 and JP19dm0107083 (TY), JP18dm0107129 (MM), JP18dm0107086 (YK), JP18dm0107107 (HY), JP18dm0107104 (AK) and JP19dm0107119 (KH), by the Grant-in-Aid for Scientific Research on Innovative Areas from the MEXT under Grant Numbers JP18H05435 (TY), JP18H05433 (AH.-T), JP18H05428 (AH.-T and TY), and JP16H06277 (HY), and by JSPS KAKENHI under Grant Number JP17H01574 (TY). In addition, this study was supported by the Collaborative Research Project of Brain Research Institute, Niigata University under Grant Numbers 2018–2809 (YK) and RIKEN Epigenetics Presidential Fund (100214–201801063606-340120) (TY).

Maelstrom regulates spermatogenesis of the silkworm, Bombyx mori

The spermatogenesis of animal is essential for the reproduction and a very large number of genes participate in this procession. The Maelstrom (Mael) is identified essential for spermatogenesis in both Drosophila and mouse, though the mechanisms appear to differ. It was initially found that Mael gene is necessary for axis specification of oocytes in Drosophila, and recent studies suggested that Mael participates in the piRNA pathway. In this study, we obtained Bombyx mori Mael mutants by using a binary transgenic CRISPR/Cas9 system and analyzed the function of Mael in B. mori, a model lepidopteran insect. The results showed that BmMael is not necessary for piRNA pathway in the ovary of silkworm, whereas it might be essential for transposon elements (TEs) repression in testis. The BmMael mutation resulted in male sterility, and further analysis established that BmMael was essential for spermatogenesis. The spermatogenesis defects occurred in the elongation stage and resulted in nuclei concentration arrest. RNA-seq and qRT-PCR analyses demonstrated that spermatogenesis defects were associated with tight junctions and apoptosis. We also found that BmMael was not involved in the silkworm sex determination pathway. Our data provide insights into the biological function of BmMael in male spermatogenesis and might be useful for developing novel methods to control lepidopteron pests.

Gliclazide alone or in combination with atorvastatin ameliorated reproductive damage in streptozotocin-induced type 2 diabetic male rats

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High-fat diet/STZ-induced T2DM caused severe damage in rat male reproductive system.

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ATV treatment slightly improved the reproductive functions.

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GLZ treatment strongly ameliorated spermatogenesis as well as testicular structure.

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ATV/GLZ combination treatment improved sperm morphology and testes structure.

Objectives

Type 2 diabetes (T2DM) is one of the most serious challenges of the 21th century with life-threatening complications and excessive health care costs. In diabetic patients, the main goal in T2DM treatment is the regulation of both blood glucose and lipid levels. For that, Gliclazide (GLZ), an oral antidiabetic, and Atorvastatin (ATV), a lipid lowering agent, are widely used drugs as combination. Diabetes has been reported severe impacts on male reproductive system; however, data obtained about ATV and GLZ treatment alone or in combination are conflicted or insufficient. Herein the effects of ATV and GLZ on male reproductive system in type 2 diabetic male rats have been investigated in the present study.

Methods

T2DM was induced by high-fat diet and single injection of streptozotocin (STZ) (35 mg/kg) in young adult male Sprague-Dawley rats. The diabetic rats were given ATV (10 mg/kg), GLZ (10 mg/kg) and ATV/GLZ (1:1, 10 mg/kg) combination by oral gavage for 28 days. The hormone levels were determined in the cardiac blood samples; and the histopathological and ultrastructural analyses were conducted in the testicular tissues and epididymal sperms.

Results

It was observed that diabetes had severe effects on testicular tissue and spermatogenesis. ATV treatment did not affect sperm count and testes structure (p > 0.05), however ameliorated sperm morphology (p < 0.05). GLZ treatment increased sperm count, and improved sperm morphology, testes structure and spermatogenesis (p < 0.05). ATV/GLZ combination treatment enhanced sperm morphology and improved testicular structure (p < 0.05) while did not affect sperm count (p > 0.05).

Conclusion

GLZ treatment regenerated testicular damage and sperm parameters whether alone or in combination with ATV in diabetic rats without affecting hypothalamic-pituitary-gonadal axis.

Identification and characterization of circular RNAs in Qinchuan cattle testis

Circular RNA (circRNA) is a new class of non-coding RNA that has recently attracted researchers' interest. Studies have demonstrated that circRNA can function as microRNA sponges or competing endogenous RNAs. Although circRNA has been explored in some species and tissues, the genetic basis of testis development and spermatogenesis in cattle remains unknown. We performed ribo-depleted total RNA-Seq to detect circRNA expression profiles of neonatal (one week old) and adult (4 years old) Qinchuan cattle testes. We obtained 91 112 596 and 80 485 868 clean reads and detected 21 753 circRNAs. A total of 4248 circRNAs were significantly differentially expressed between neonatal and adult cattle testes. Among these circRNAs, 2225 were upregulated, and 2023 were downregulated in adult cattle testis. Genomic feature, length distribution and other characteristics of the circRNAs in cattle testis were studied. Moreover, Gene Ontology and KEGG pathway analyses were performed for source genes of circRNAs. These source genes were mainly involved in tight junction, adherens junction, TGFβ signalling pathway and reproduction, such as PIWIL1, DPY19L2, SLC26A8, IFT81, SMC1B, IQCG and TTLL5. CircRNA expression patterns were validated by RT-qPCR. Our discoveries provide a solid foundation for the identification and characterization of key circRNAs involved in testis development or spermatogenesis.

50 years of spermatogenesis: Sertoli cells and their interactions with germ cells

The complex morphology of the Sertoli cells and their interactions with germ cells has been a focus of investigators since they were first described by Enrico Sertoli. In the past 50 years, information on Sertoli cells has transcended morphology alone to become increasingly more focused on molecular questions. The goal of investigators has been to understand the role of the Sertoli cells in spermatogenesis and to apply that information to problems relating to male fertility. Sertoli cells are unique in that they are a nondividing cell population that is active for the reproductive lifetime of the animal and cyclically change morphology and gene expression. The numerous and distinctive junctional complexes and membrane specializations made by Sertoli cells provide a scaffold and environment for germ cell development. The increased focus of investigators on the molecular components and putative functions of testicular cells has resulted primarily from procedures that isolate specific cell types from the testicular milieu. Products of Sertoli cells that influence germ cell development and vice versa have been characterized from cultured cells and from the application of transgenic technologies. Germ cell transplantation has shown that the Sertoli cells respond to cues from germ cells with regard to developmental timing and has furthered a focus on spermatogenic stem cells and the stem cell niche. Very basic and universal features of spermatogenesis such as the cycle of the seminiferous epithelium and the spermatogenic wave are initiated by Sertoli cells and maintained by Sertoli-germ cell cooperation.

Identification and characterization of circular RNAs in Qinchuan cattle testis

Circular RNA (circRNA) is a new class of non-coding RNA that has recently attracted researchers' interest. Studies have demonstrated that circRNA can function as microRNA sponges or competing endogenous RNAs. Although circRNA has been explored in some species and tissues, the genetic basis of testis development and spermatogenesis in cattle remains unknown. We performed ribo-depleted total RNA-Seq to detect circRNA expression profiles of neonatal (one week old) and adult (4 years old) Qinchuan cattle testes. We obtained 91 112 596 and 80 485 868 clean reads and detected 21 753 circRNAs. A total of 4248 circRNAs were significantly differentially expressed between neonatal and adult cattle testes. Among these circRNAs, 2225 were upregulated, and 2023 were downregulated in adult cattle testis. Genomic feature, length distribution and other characteristics of the circRNAs in cattle testis were studied. Moreover, Gene Ontology and KEGG pathway analyses were performed for source genes of circRNAs. These source genes were mainly involved in tight junction, adherens junction, TGFβ signalling pathway and reproduction, such as PIWIL1, DPY19L2, SLC26A8, IFT81, SMC1B, IQCG and TTLL5. CircRNA expression patterns were validated by RT-qPCR. Our discoveries provide a solid foundation for the identification and characterization of key circRNAs involved in testis development or spermatogenesis.

Effects of bisphenol A and its analogs on reproductive health: A mini review

Known endocrine disruptor bisphenol A (BPA) has been shown to be a reproductive toxicant in animal models. Its structural analogs: bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) are increasingly being used in consumer products. However, these analogs may exert similar adverse effects on the reproductive system, and their toxicological data are still limited. This mini-review examined studies on both BPA and BPA analog exposure and reproductive toxicity. It outlines the current state of knowledge on human exposure, toxicokinetics, endocrine activities, and reproductive toxicities of BPA and its analogs. BPA analogs showed similar endocrine potencies when compared to BPA, and emerging data suggest they may pose threats as reproductive hazards in animal models. While evidence based on epidemiological studies is still weak, we have utilized current studies to highlight knowledge gaps and research needs for future risk assessments.

Mesoporous silica nanoparticle is comparatively safer than zinc oxide nanoparticle which can cause profound steroidogenic effects on pregnant mice and male offspring exposed in utero

The increasing use of nanomaterials has naturally caused heightened concerns about their potential risks to human and animal health. We investigated the effect of zinc oxide nanoparticles (ZnO NPs) and mesoporous silica nanoparticles (MSN) on steroidogenesis in the corpus luteum (CL) of pregnant mice and testis of male offspring. Pregnant albino mice were exposed to ZnO NPs and MSN for 2 days on alternate days, gestation days 15–19. Hepatic injury marker enzymes increased in the higher concentration of NM-exposed mother mice, but histological examination revealed no changes in the placenta of pregnant mice, whereas testis of male offspring showed gross pathological changes. The expression pattern of progesterone biosynthesis-related genes was also altered in the CL of NP-exposed pregnant mice. In utero exposure of ZnO NPs increased the relative expression of StAR in 100 mg/kg body weight (BW) ZnO NP-treated and bulk ZnO-treated groups and P450 side-chain cleavage enzyme (P450scc) in 50 mg/kg BW ZnO NP-treated and 100 mg/kg of bulk ZnO-treated male offspring. Serum testosterone concentration significantly increased in the 100 mg/kg of bulk ZnO-treated group and decreased in the 250 mg/kg of MSN-treated group and a single dose of 300 mg/Kg BW of ZnO NPs caused miscarriages and adversely affected the developing foetus in mice.

Diabetes mellitus- induction: Effect of different streptozotocin doses on male reproductive parameters

Diabetes mellitus (DM) is reported to be involved in male reproductive impairment, and its impact is evident in the increased prevalence of infertility. Various studies have reported that a single parenteral injection of <40 mg/kg Streptozotocin (STZ) is ineffective in ablating pancreatic β-cells and creating a rat model to investigate the effect of DM on the male reproductive system. This study therefore aims to validate these claims. Adult male Wistar rats received either a single intraperitoneal injection of STZ (30 mg/kg or 60 mg/kg) or saline (0.9%, Control). Diabetes was confirmed after 72 h if plasma glucose levels were ≥14 mmol/L. Body weight, glucose level, fluid and food intake were measured weekly. Animals were sacrificed after 8 weeks of treatment by an overdose of sodium pentobarbital (160 mg/kg body weight). The testis and epididymis were harvested and weighed prior to preparation for histological evaluation. Epididymal sperm morphology was analysed using computer aided sperm analysis (CASA). STZ60 animals presented with significantly lower body weights compared to both control and STZ30 groups. Animals in both STZ30 and STZ60 groups showed decreased normal sperm morphology compared to control. Histological evaluation of the testes showed a decrease in the number of spermatozoa in the seminiferous tubules of animals in the STZ30 and STZ60 groups compared to control. A complete absence of spermiogenesis was observed in the seminiferous tubules of STZ60 animals. These findings prove that an STZ concentration of 30 mg/kg, which is much lower than the reported 40 mg/kg, has adverse effects on the male reproductive system via its diabetogenic effect and can therefore be used to study the impact of DM on male fertility.

Hormone induced differential transcriptome analysis of Sertoli cells during postnatal maturation of rat testes

Sertoli cells (Sc) are unique somatic cells of testis that are the target of both FSH and testosterone (T) and regulate spermatogenesis. Although Sc of neonatal rat testes are exposed to high levels of FSH and T, robust differentiation of spermatogonial cells becomes conspicuous only after 11-days of postnatal age. We have demonstrated earlier that a developmental switch in terms of hormonal responsiveness occurs in rat Sc at around 12 days of postnatal age during the rapid transition of spermatogonia A to B. Therefore, such “functional maturation” of Sc, during pubertal development becomes prerequisite for the onset of spermatogenesis. However, a conspicuous difference in robust hormone (both T and FSH) induced gene expression during the different phases of Sc maturation restricts our understanding about molecular events necessary for the spermatogenic onset and maintenance. Here, using microarray technology, we for the first time have compared the differential transcriptional profile of Sc isolated and cultured from immature (5 days old), maturing (12 days old) and mature (60 days old) rat testes. Our data revealed that immature Sc express genes involved in cellular growth, metabolism, chemokines, cell division, MAPK and Wnt pathways, while mature Sc are more specialized expressing genes involved in glucose metabolism, phagocytosis, insulin signaling and cytoskeleton structuring. Taken together, this differential transcriptome data provide an important resource to reveal the molecular network of Sc maturation which is necessary to govern male germ cell differentiation, hence, will improve our current understanding of the etiology of some forms of idiopathic male infertility.

Essential roles of Akt/Snail pathway in microcystin-LR-induced tight junction toxicity in Sertoli cell

Microcystin (MC)-LR is a cyclic heptapeptide that acts as a potent reproductive system toxin. However, the underlying pathways of MCLR-induced reproductive system toxicity have not been well elucidated. The blood-testis barrier is mainly constituted by tight junctions (TJs) between adjacent Sertoli cells in the seminiferous epithelium near the basement membrane. The present study was designed to investigate changes in TJs and the underlying pathway in MC-LR-induced TJs toxicity in Sertoli cell. In our study, the transepithelial electrical resistance (TER) value was decreased in a dose dependent manner due to the markers of TJs occludin, claudin and zonula occludens-1 (ZO-1) expression decline. MC-LR is shown to induce cytotoxicity by inhibiting protein phosphatase 2A (PP2A) activity. Our results also showed that the PP2A activity presented a dose-dependent decline. Moreover, MC-LR stimulated protein expression of snail by Akt/GSK-3β activation. The activated Akt/GSK-3β and snail signaling pathway largely accounted for MC-LRinduced TJs toxicity, which could be partially reversed by snail siRNA interference or AKT chemical inhibitor in TM4 cells. These findings indicated that MC-LR inhibit the protein expression of TJs, and the activation of Akt/Snail signaling pathways due to PP2A inhibition is proposed to participate in this process.

Fluorochloridone induces primary cultured Sertoli cells apoptosis: Involvement of ROS and intracellular calcium ions-mediated ERK1/2 activation

Fluorochloridone (FLC) is a widely used pyrrolidone selective herbicide and reported to induce testis injuries in male rats, but the underlying mechanism is largely unknown. In the present study, primary-cultured Sertoli cells were exposed to FLC at the concentration of 0-10.00μM to study the mechanism of FLC-induced apoptosis. The roles of ROS, intracellular calcium, endoplasmic reticulum (ER), and ERK1/2 were looked at with ROS scavenger N-acetyl-cysteine (NAC), intracellular calcium chelator BAPTA-AM, ER calcium depleting agent thapsigargin (TG), and ERK1/2 inhibitor U0126, respectively. FLC induced dose-dependent apoptosis increase as well as the elevation in levels of ROS, intracellular calcium, and ERK1/2 activation. FLC treatment led to constantly increasing apoptotic rates and ERK1/2 activation over time, while inversed-V shaped change tendencies of ROS and intracellular calcium levels were observed. FLC-induced ROS generation disrupted the intracellular calcium homeostasis by attacking the ER, and the elevated intracellular calcium levels resulted in ERK1/2 over-phosphorylation and consequently promoted Sertoli cell apoptosis. Taken together, ROS and intracellular calcium-mediated ERK1/2 activation led to FLC-induced Sertoli cell apoptosis.

Generation and characteristics of human Sertoli cell line immortalized by overexpression of human telomerase

Sertoli cells are required for normal spermatogenesis and they can be reprogrammed to other types of functional cells. However, the number of primary Sertoli cells is rare and human Sertoli cell line is unavailable. In this study, we have for the first time reported a stable human Sertoli cell line, namely hS1 cells, by overexpression of human telomerase. The hS1 cells expressed a number of hallmarks for human Sertoli cells, including SOX9, WT1, GDNF, SCF, BMP4, BMP6, GATA4, and VIM, and they were negative for 3β-HSD, SMA, and VASA. Higher levels of AR and FSHR were observed in hS1 cells compared to primary human Sertoli cells. Microarray analysis showed that 70.4% of global gene profiles of hS1 cells were similar to primary human Sertoli cells. Proliferation assay demonstrated that hS1 cells proliferated rapidly and they could be passaged for more than 30 times in 6 months. Neither Y chromosome microdeletion nor tumorgenesis was detected in this cell line and 90% normal karyotypes existed in hS1 cells. Collectively, we have established the first human Sertoli cell line with phenotype of primary human Sertoli cells, an unlimited proliferation potential and high safety, which could offer sufficient human Sertoli cells for basic research as well as reproductive and regenerative medicine.

Molecular and structural changes related to hepatitis E virus antigen and its expression in testis inducing apoptosis in Mongolian gerbil model

Hepatitis E virus (HEV) infection has been associated with a wide range of extrahepatic manifestations, so this study was designed to examine the effect and role of HEV on structural and molecular changes in the testicular tissues of Mongolian gerbils experimentally infected with swine HEV. HEV RNA was first detected in testis at 14 days post-inoculation and reached a peak between 28 and 42 days later with viral load between 3.12 and 6.23 logs/g by PCR assays. Changes including vacuolation, sloughing of germ cells, formation of multinuclear giant cells, degeneration, necrosis of tubules and damaged blood-testis barrier were observed through transmission electron microscopy. HEV ORF2 antigen was detected in the sperm cell cytoplasm along with decrease in relative protein of zonula occludens-1 through immunohistochemistry. HEV ORF3 antigen and ZO-1 protein were detectable by Western blotting. Lower (P<.05) serum testosterone and higher (P<.05) blood urea nitrogen level was observed in inoculated Mongolian gerbils. Likewise, increased (P<.05) germ cell apoptosis rate was detected with significant increased expression of Fas-L and Fas in HEV-inoculated groups at each time points. Up-regulation (P<.05 or P<.01) in mRNA level of Fas-L, Fas, Bax, Bcl-2 and caspase-3 was observed in HEV RNA-positive testes. Our study demonstrated that after experimental inoculation, HEV can be detected in testis tissues and viral proteins produce structural and molecular changes that in turn disrupt the blood-testis barrier and induce germ cell apoptosis.

The Bile Acid Nuclear Receptor FXRα Is a Critical Regulator of Mouse Germ Cell Fate

Spermatogenesis is the process by which spermatozoa are generated from spermatogonia. This cell population is heterogeneous, with self-renewing spermatogonial stem cells (SSCs) and progenitor spermatogonia that will continue on a path of differentiation. Only SSCs have the ability to regenerate and sustain spermatogenesis. This makes the testis a good model to investigate stem cell biology. The Farnesoid X Receptor alpha (FXRα) was recently shown to be expressed in the testis. However, its global impact on germ cell homeostasis has not yet been studied. Here, using a phenotyping approach in Fxrα^−/− mice, we describe unexpected roles of FXRα on germ cell physiology independent of its effects on somatic cells. FXRα helps establish and maintain an undifferentiated germ cell pool and in turn influences male fertility. FXRα regulates the expression of several pluripotency factors. Among these, in vitro approaches show that FXRα controls the expression of the pluripotency marker Lin28 in the germ cells.

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FXRα regulated germ cell apoptotis independently of androgen homeostasis

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FXRα controls germ cell differentiation

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FXRα regulates the establishment and maintenance of undifferentiated germ cells

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In germ cells, FXRα controls the expression of pluripotency markers such as Lin28

BMP6 Regulates Proliferation and Apoptosis of Human Sertoli Cells Via Smad2/3 and Cyclin D1 Pathway and DACH1 and TFAP2A Activation

Sertoli cells are essential for regulating normal spermatogenesis. However, the mechanisms underlying human Sertoli cell development remain largely elusive. Here we examined the function and signaling pathways of BMP6 in regulating human Sertoli cells. RT-PCR, immunocytochemistry and Western blots revealed that BMP6 and its multiple receptors were expressed in human Sertoli cells. CCK-8 and EDU assays showed that BMP6 promoted the proliferation of Sertoli cells. Conversely, BMP6 siRNAs inhibited the division of these cells. Annexin V/PI assay indicated that BMP6 reduced the apoptosis in human Sertoli cells, whereas BMP6 knockdown assumed reverse effects. BMP6 enhanced the expression levels of ZO1, SCF, GDNF and AR in human Sertoli cells, and ELISA assay showed an increase of SCF by BMP6 and a reduction by BMP6 siRNAs. Notably, Smad2/3 phosphorylation and cyclin D1 were enhanced by BMP6 and decreased by BMP6 siRNAs in human Sertoli cells. The levels of DACH1 and TFAP2A were increased by BMP6 and reduced by BMP6 siRNAs, and the growth of human Sertoli cells was inhibited by these siRNAs. Collectively, these results suggest that BMP6 regulates the proliferation and apoptosis of human Sertoli cells via activating the Smad2/3/cyclin D1 and DACH1 and TFAP2A pathway.

Polydeoxyribonucleotide, an Adenosine-A2A Receptor Agonist, Preserves Blood Testis Barrier from Cadmium-Induced Injury

Cadmium (Cd) impairs blood-testis barrier (BTB). Polydeoxyribonucleotide (PDRN), an adenosine A_2A agonist, has positive effects on male reproductive system. We investigated the effects of PDRN on the morphological and functional changes induced by Cd in mice testes. Adult Swiss mice were divided into four groups: controls administered with 0.9% NaCl (1 ml/kg, i.p., daily) or with PDRN (8 mg/kg, i.p. daily), animals challenged with Cd chloride (CdCl₂; 2 mg/kg, i.p, daily) and animals challenged with CdCl₂ (2 mg/kg, i.p., daily) and treated with PDRN (8 mg/kg, i.p., daily). Experiments lasted 14 days. Testes were processed for biochemical, structural, and ultrastructural evaluation and hormones were assayed in serum. CdCl₂ increased pERK 1/2 expression and Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) levels; it decreased testosterone (TE) and inhibin-B levels and induced structural damages in extratubular compartment and in seminiferous epithelium, with ultrastructural features of BTB disruption. Many TUNEL-positive germ cells were present. CdCl₂ increased tubular TGF-β3 immunoreactivity and reduced claudin-11, occludin, and N-cadherin immunoreactivity. PDRN administration reduced pERK 1/2 expression, FSH, and LH levels; it increased TE and inhibin-B levels, ameliorated germinal epithelium changes and protected BTB ultrastructure. Few TUNEL-positive germ cells were present and the extratubular compartment was preserved. Furthermore, PDRN decreased TGF-β3 immunoreactivity and enhanced claudin-11, occludin, and N-cadherin immunoreactivity. We demonstrate a protective effect of PDRN on Cd-induced damages of BTB and suggest that PDRN may play an important role against Cd, particularly against its harmful effects on gametogenesis.

Pentacle gold-copper alloy nanocrystals: a new system for entering male germ cells in vitro and in vivo

Gold-based nanocrystals have attracted considerable attention for drug delivery and biological applications due to their distinct shapes. However, overcoming biological barriers is a hard and inevitable problem, which restricts medical applications of nanomaterials in vivo. Seeking for an efficient transportation to penetrate biological barriers is a common need. There are three barriers: blood-testis barrier, blood-placenta barrier, and blood-brain barrier. Here, we pay close attention to the blood-testis barrier. We found that the pentacle gold-copper alloy nanocrystals not only could enter GC-2 cells in vitro in a short time, but also could overcome the blood-testis barrier and enter male germ cells in vivo. Furthermore, we demonstrated that the entrance efficiency would become much higher in the development stages. The results also suggested that the pentacle gold-copper alloy nanocrystals could easier enter to germ cells in the pathological condition. This system could be a new method for theranostics in the reproductive system.

Effects of Fetal Exposure to Asian Sand Dust on Development and Reproduction in Male Offspring

In recent experimental studies, we reported the aggravating effects of Asian sand dust (ASD) on male reproduction in mice. However, the effects of fetal ASD exposure on male reproduction have not been investigated. The present study investigated the effects of fetal ASD exposure on reproduction in male offspring. Using pregnant CD-1 mice, ASD was administered intratracheally on days 7 and 14 of gestation, and the reproduction of male offspring was determined at 5, 10, and 15 weeks after birth. The secondary sex ratio was significantly lower in the fetal ASD-exposed mice than in the controls. Histologic examination showed partial vacuolation of seminiferous tubules in immature mice. Moreover, daily sperm production (DSP) was significantly less in the fetal ASD-exposed mice than in the controls. DSP in the fetal ASD-exposed mice was approximately 10% less than the controls at both 5 and 10 weeks. However, both the histologic changes and the DSP decrease were reversed as the mice matured. These findings suggest that ASD exposure affects both the fetal development and the reproduction of male offspring. In the future, it will be necessary to clarify the onset mechanisms of ASD-induced male fetus death and male reproductive disorders.