Expressions of Sox9, Sox5, and Sox13 transcription factors in mice testis during postnatal development

Regulatory mechanisms of SoxD transcription factors and their influences on male fertility

Members of the SRY-related box (SOX) subfamily D (SoxD) of transcription factors are well conserved among vertebrate species and play important roles in different stages of male reproductive development. In mammals, the SoxD subfamily contains three members: SOX5, SOX6 and SOX13. Here, we describe their implications in testicular development and spermatogenesis, contributing to fertility. We also cover the mechanisms of action of SoxD transcription factors in gene regulation throughout male development. The specificity of activation of target genes by SoxD members depends, in part, on their post-translational modifications and interactions with other partners. Sperm production in adult males requires the coordination in the regulation of gene expression by different members of the SoxD subfamily of transcription factors in the testis. Specifically, the regulation of genes promoting adequate spermatogenesis by SoxD members is discussed in comparison between species.

Identification of key genes affecting sperm motility in chicken based on whole-transcriptome sequencing

Sperm motility is an important index for the evaluation of semen quality. Improving sperm motility is important to improve reproductive performance, promote breeding process, and reduce production cost. However, the molecular mechanisms regulating sperm motility in chickens remain unclear. In this study, histological observation and whole-transcriptome analysis were performed on testicular tissue of chickens with high and low sperm motility. Histological observations showed that roosters with high sperm motility exhibited better semen quality than those with low sperm motility. In addition, the germinal epithelial cells of roosters with low sperm motility were loosely arranged and contained many vacuoles. RNA-seq results revealed the expression of 23,033 mRNAs, 2,893 lncRNAs, and 515 miRNAs in chicken testes. Among them, there were 417 differentially expressed mRNAs (DEmRNAs), 106 differentially expressed lncRNAs (DElncRNAs), and 15 differentially expressed miRNAs (DEmiRNAs) between high and low sperm motility testes. These differentially expressed genes were involved in the G protein-coupled receptor signaling pathway, cilia structure, Wnt signaling, MAPK signaling, GnRH signaling, and mTOR signaling. By integrating the competitive relationships between DEmRNAs, DElncRNAs, and DEmiRNAs, we identified the regulatory pathway of MSTRG.3077.3/MSTRG.9085.1-gga-miR-138-5p-CADM1 and MSTRG.2290.1-gga-miR-142-3p-GNAQ/PPP3CA as crucial in the modulation of chicken sperm motility. This study provides new insights into the function and mechanism of ceRNAs in regulating sperm motility in chicken testes.

A single-cell landscape of triptolide-associated testicular toxicity in mice

Triptolide is a key active component of the widely used traditional Chinese herb medicine Tripterygium wilfordii Hook. F. Although triptolide exerts multiple biological activities and shows promising efficacy in treating inflammatory-related diseases, its well-known safety issues, especially reproductive toxicity has aroused concerns. However, a comprehensive dissection of triptolide-associated testicular toxicity at single cell resolution is still lacking. Here, we observed testicular toxicity after 14 days of triptolide exposure, and then constructed a single-cell transcriptome map of 59,127 cells in mouse testes upon triptolide-treatment. We identified triptolide-associated shared and cell-type specific differentially expressed genes, enriched pathways, and ligand-receptor pairs in different cell types of mouse testes. In addition to the loss of germ cells, our results revealed increased macrophages and the inflammatory response in triptolide-treated mouse testes, suggesting a critical role of inflammation in triptolide-induced testicular injury. We also found increased reactive oxygen species (ROS) signaling and downregulated pathways associated with spermatid development in somatic cells, especially Leydig and Sertoli cells, in triptolide-treated mice, indicating that dysregulation of these signaling pathways may contribute to triptolide-induced testicular toxicity. Overall, our high-resolution single-cell landscape offers comprehensive information regarding triptolide-associated gene expression profiles in major cell types of mouse testes at single cell resolution, providing an invaluable resource for understanding the underlying mechanism of triptolide-associated testicular injury and additional discoveries of therapeutic targets of triptolide-induced male reproductive toxicity.

The transcription factors Creb1 and Cebpb regulate Sox9 promoter activity in TM4 Sertoli cells

In Sertoli cells, the Sox9 gene is essential for testicular development and normal spermatogenesis. SOX9 is critical for postnatal Sertoli cells differentiation and proliferation in the testis. However, the molecular mechanisms that specifically regulate its expression are not entirely understood. Sox9 expression is regulated by CREB1 and CEBPB in other biological contexts such as during chondrogenesis and in rat thyroid follicular cells. We hypothesized that Sox9 promoter activity is regulated by CREB1 and CEBPB in Sertoli cells. Our results show that Sox9 expression is dependent on the activation of these transcription factors by the cAMP/PKA signaling pathway in TM4 Sertoli cells. Chromatin immunoprecipitation and promoter/reporter luciferase assays with 5' promoter deletions and site-directed mutagenesis demonstrated that CREB1 is being recruited to a DNA regulatory element at -141 bp of the Sox9 promoter region. Such regulation is dependent on the cAMP/PKA signaling pathway, resulting in phosphorylation of CREB1. Activation of Sox9 expression by CEBPB may involve its recruitment to the proximal promoter region by protein-protein interaction with CREB1. Thus, we have shown that the Sox9 promoter is being regulated by the transcription factors CREB1 and CEBPB in TM4 Sertoli cells and involve their recruitment to the proximal promoter region.

Multi-breed genomic predictions and functional variants for fertility of tropical bulls

Worldwide, most beef breeding herds are naturally mated. As such, the ability to identify and select fertile bulls is critically important for both productivity and genetic improvement. Here, we collected ten fertility-related phenotypes for 6,063 bulls from six tropically adapted breeds. Phenotypes were comprised of four bull conformation traits and six traits directly related to the quality of the bull's semen. We also generated high-density DNA genotypes for all the animals. In total, 680,758 single nucleotide polymorphism (SNP) genotypes were analyzed. The genomic correlation of the same trait observed in different breeds was positive for scrotal circumference and sheath score on most breed comparisons, but close to zero for the percentage of normal sperm, suggesting a divergent genetic background for this trait. We confirmed the importance of a breed being present in the reference population to the generation of accurate genomic estimated breeding values (GEBV) in an across-breed validation scenario. Average GEBV accuracies varied from 0.19 to 0.44 when the breed was not included in the reference population. The range improved to 0.28 to 0.59 when the breed was in the reference population. Variants associated with the gene HDAC4, six genes from the spermatogenesis-associated (SPATA) family of proteins, and 29 transcription factors were identified as candidate genes. Collectively these results enable very early in-life selection for bull fertility traits, supporting genetic improvement strategies currently taking place within tropical beef production systems. This study also improves our understanding of the molecular basis of male fertility in mammals.

Mechanisms of autoimmune pathology in post-COVID syndrome

   One of the delayed consequences of SARS-CoV-2 infection is post-acute COVID-19 – polymorphic disorders of various organ systems that affect COVID-19 convalescents and persist for more than four weeks after an acute infection. Due to the infectious nature of the COVID-19, we would like to pay special attention to complications from the immune system, especially concomitant and new-onset autoimmune pathology. This review analyzes the current state of the issue of post-acute COVID-19 complications, discusses the molecular features of the SARS-CoV-2 virus and the mechanisms underlying the impaired immune response during acute COVID-19 infection and the occurrence of autoimmune and autoinflammatory conditions during convalescence. Particular attention is paid to the molecular mimicry of antigenic determinants of the SARS-CoV-2 virus, which are structurally similar to the epitopes of human autoantigens. The current data on post-acute COVID-19 autoimmune complications from humoral immunity and the endocrine system, as well as reproductive disorders faced by male patients are presented. For the first time, we hypothesize a role of the structural homology of the human SOX13 autoantigen (HMG box factor SOX13) associated with diabetes mellitus and SARS-CoV-2 envelope (E) protein in the development of the post-acute COVID-19 autoimmune pathologies. Due to the structural similarity of the two proteins and the overlap of their immunogenic regions, we suggest that the increased risk of developing diabetes mellitus and reproductive disorders in men after suffering from COVID-19 may be associated with immunological cross-reactivity.

Sox13 is a novel flow-sensitive transcription factor that prevents inflammation by repressing chemokine expression in endothelial cells

Atherosclerosis is a chronic inflammatory disease and occurs preferentially in arterial regions exposed to disturbed blood flow (d-flow) while the stable flow (s-flow) regions are spared. D-flow induces endothelial inflammation and atherosclerosis by regulating endothelial gene expression partly through the flow-sensitive transcription factors (FSTFs). Most FSTFs, including the well-known Kruppel-like factors KLF2 and KLF4, have been identified from in vitro studies using cultured endothelial cells (ECs). Since many flow-sensitive genes and pathways are lost or dysregulated in ECs during culture, we hypothesized that many important FSTFs in ECs in vivo have not been identified. We tested the hypothesis by analyzing our recent gene array and single-cell RNA sequencing (scRNAseq) and chromatin accessibility sequencing (scATACseq) datasets generated using the mouse partial carotid ligation model. From the analyses, we identified 30 FSTFs, including the expected KLF2/4 and novel FSTFs. They were further validated in mouse arteries in vivo and cultured human aortic ECs (HAECs). These results revealed 8 FSTFs, SOX4, SOX13, SIX2, ZBTB46, CEBPβ, NFIL3, KLF2, and KLF4, that are conserved in mice and humans in vivo and in vitro. We selected SOX13 for further studies because of its robust flow-sensitive regulation, preferential expression in ECs, and unknown flow-dependent function. We found that siRNA-mediated knockdown of SOX13 increased endothelial inflammatory responses even under the unidirectional laminar shear stress (ULS, mimicking s-flow) condition. To understand the underlying mechanisms, we conducted an RNAseq study in HAECs treated with SOX13 siRNA under shear conditions (ULS vs. oscillatory shear mimicking d-flow). We found 94 downregulated and 40 upregulated genes that changed in a shear- and SOX13-dependent manner. Several cytokines, including CXCL10 and CCL5, were the most strongly upregulated genes in HAECs treated with SOX13 siRNA. The robust induction of CXCL10 and CCL5 was further validated by qPCR and ELISA in HAECs. Moreover, the treatment of HAECs with Met-CCL5, a specific CCL5 receptor antagonist, prevented the endothelial inflammation responses induced by siSOX13. In addition, SOX13 overexpression prevented the endothelial inflammation responses. In summary, SOX13 is a novel conserved FSTF, which represses the expression of pro-inflammatory chemokines in ECs under s-flow. Reduction of endothelial SOX13 triggers chemokine expression and inflammatory responses, a major proatherogenic pathway.

Ssc-MiR-21-5p and Ssc-MiR-615 Regulates the Proliferation and Apoptosis of Leydig Cells by Targeting SOX5

Leydig cells (LCs) are the predominant cells of androgen production, which plays key roles in spermatogenesis and maintaining male secondary sexual characteristics. Abnormal development of LCs affects androgen levels in vivo, affects fertility and may even lead to infertility. Little is known about the regulation mechanism on LCs’ development and maturation in domestic animals, especially the regulation of non-coding RNAs. In this study, we continued to dig deeper in the previous RNA-seq data of porcine LCs from our group, combined with detecting the expression profiles in different tissues and different types of cells in the testis, to screen out candidate microRNAs (miRNAs) that may affect the regulation of LCs. A total of two miRNAs, ssc-miR-21-5p and ssc-miR-615 (“ssc” is omitted below), were finally determined. After overexpression and interference of miRNAs in vitro, the effects of candidate miRNAs on the proliferation and apoptosis of TM3 (mouse Leydig cell line) were explored. The results showed that miR-21-5p led to a decrease in TM3 cell density and p53 (apoptosis related protein) expression. Meanwhile, miR-21-5p decreased EdU positive cell numbers, but increased TUNEL positive cell numbers, suggesting miR-21-5p could inhibit proliferation and promote apoptosis. Conversely, miR-615 could increase TM3 cell density. Western blot and TUNEL assay indicated miR-615 inhibited apoptosis, but had no effect on proliferation. In addition, Sox5 was identified a potential target gene of these two miRNAs by Dual-Luciferase reporter system assay. Our findings about functions of miRNAs in TM3 and the mapping of miRNAs-target gene regulatory network would provide an important basis for the further elucidation of miRNAs in regulating pig LCs.

Eef2k is not required for fertility in male mice

Background

Eukaryotic elongation factor-2 kinase (Eef2k) is a protein kinase associated with the calmodulin-induced signaling pathway and an atypical alpha-kinase family member. Eef2k-mediated phosphorylation of eukaryotic translation elongation factor 2 (Eef2) can inhibit the functionality of this protein, altering protein translation. Prior work suggests Eef2k to be overexpressed in breast, pancreatic, brain, and lung cancers wherein it may control key processes associated with apoptosis, autophagy, and cell cycle progression. The functional importance of Eef2k in the testes of male mice, however, has yet to be clarified.

Methods

A CRISPR/Cas9 approach was used to generate male Eef2k-knockout mice, which were evaluated for phenotypic changes in epididymal or testicular tissues through histological and immunofluorescent staining assays. In addition, TUNEL staining was conducted to assess the apoptotic death of cells in the testis. Fertility, sperm counts, and sperm motility were further assessed.

Results

Male Eef2k-knockout mice were successfully generated, and exhibited normal fertility and development. No apparent differences were observed with respect to spermatogenesis, sperm counts, or germ cell apoptosis when comparing male Eef2k ^-/- and Eef2k ^+/+ mice.

Conclusions

Male Eef2k-knockout mice remained fertile and were free of any evident developmental or spermatogenic abnormalities, suggesting Eef2k to be dispensable in the context of male fertility.

Effect and in silico characterization of genetic variants associated with severe spermatogenic disorders in a large Iberian cohort

BACKGROUND

Severe spermatogenic failure (SpF) represents the most extreme manifestation of male infertility, as it decreases drastically the semen quality leading to either severe oligospermia (SO, <5 million spermatozoa/mL semen) or non-obstructive azoospermia (NOA, complete lack of spermatozoa in the ejaculate without obstructive causes).

OBJECTIVES

The main objective of the present study is to analyze in the Iberian population the effect of 6 single-nucleotide polymorphisms (SNPs) previously associated with NOA in Han Chinese through genome-wide association studies (GWAS) and to establish their possible functional relevance in the development of specific SpF patterns.

MATERIALS AND METHODS

We genotyped 674 Iberian infertile men (including 480 NOA and 194 SO patients) and 1058 matched unaffected controls for the GWAS-associated variants PRMT6-rs12097821, PEX10-rs2477686, CDC42BPA-rs3000811, IL17A-rs13206743, ABLIM1-rs7099208, and SOX5-rs10842262. Their association with SpF, SO, NOA, and different NOA phenotypes was evaluated by logistic regression models, and their functional relevance was defined by comprehensive interrogation of public resources.

RESULTS

ABLIM1-rs7099208 was associated with SpF under both additive (OR = 0.86, p = 0.036) and dominant models (OR = 0.78, p = 0.026). The CDC42BPA-rs3000811 minor allele frequency was significantly increased in the subgroup of NOA patients showing maturation arrest (MA) of germ cells compared to the remaining NOA cases under the recessive model (OR = 4.45, p = 0.044). The PEX10-rs2477686 SNP was associated with a negative testicular sperm extraction (TESE) outcome under the additive model (OR = 1.32, p = 0.034). The analysis of functional annotations suggested that these variants affect the testis-specific expression of nearby genes and that lincRNA may play a role in SpF.

CONCLUSIONS

Our data support the association of three previously reported NOA risk variants in Asians (ABLIM1-rs7099208, CDC42BPA-rs3000811, and PEX10-rs2477686) with different manifestations of SpF in Iberians of European descent, likely by influencing gene expression and lincRNA deregulation.

Comparative analysis of hypothalamus transcriptome between laying hens with different egg-laying rates

Egg-laying performance is one of the most important economic traits in the poultry industry. Commercial layers can lay one egg almost every day during their peak-laying period. However, many Chinese indigenous chicken breeds show a relatively low egg-laying rate, even during their peak-laying period. To understand what makes the difference in egg production, we compared the hypothalamus transcriptome profiles of Lushi blue-shelled-egg chickens (LBS), a Chinese indigenous breed with low egg-laying rate and Rhode Island Red chickens (RIR), a commercial layer with relatively high egg-laying rate using RNA-seq. A total of 753 differentially expressed genes (DEGs) were obtained. Of these DEGs, 38 genes were enriched in 2 Gene Ontology (GO) terms, namely reproduction term and the reproductive process term, and 6 KEGG pathways, namely Wnt signaling pathway, Oocyte meiosis, GnRH signaling pathway, Thyroid hormone signaling pathway, Thyroid hormone synthesis and MAPK signaling pathway, which have been long known to be involved in egg production regulation. To further determine the core genes from the 38 DEGs, protein-protein interaction (PPI) network, co-expression network and transcriptional regulatory network analyses were carried out. After integrated analysis and experimental validation, 4 core genes including RAC1, MRE11A, MAP7 and SOX5 were identified as the potential core genes that are responsible for the laying-rate difference between the 2 breeds. These findings paved the way for future investigating the mechanism of egg-laying regulation and enriched the chicken reproductive regulation theory.

Deficiency in insulin-like growth factors signalling in mouse Leydig cells increase conversion of testosterone to estradiol because of feminization

AIM

A growing body of evidence pointed correlation between insulin-resistance, testosterone level and infertility, but there is scarce information about mechanisms. The aim of this study was to identify the possible mechanism linking the insulin-resistance with testosterone-producing-Leydig-cells functionality.

METHODS

We applied in vivo and in vitro approaches. The in vivo model of functional genomics is represented by INSR/IGF1R-deficient-testosterone-producing Leydig cells obtained from the prepubertal (P21) and adult (P80) male mice with insulin + IGF1-receptors deletion in steroidogenic cells (Insr/Igf1r-DKO). The in vitro model of INSR/IGF1R-deficient-cell was mimicked by blockade of insulin/IGF1-receptors on the primary culture of P21 and P80 Leydig cells.

RESULTS

Leydig-cell-specific-insulin-resistance induce the development of estrogenic characteristics of progenitor Leydig cells in prepubertal mice and mature Leydig cells in adult mice, followed with a dramatic reduction of androgen phenotype. Level of androgens in serum, testes and Leydig cells decrease as a consequence of the dramatic reduction of steroidogenic capacity and activity as well as all functional markers of Leydig cell. Oppositely, the markers for female-steroidogenic-cell differentiation and function increase. The physiological significances are the higher level of testosterone-to-estradiol-conversion in double-knock-out-mice of both ages and few spermatozoa in adults. Intriguingly, the transcription of pro-male sexual differentiation markers Sry/Sox9 increased in P21-Leydig-cells, questioning the current view about the antagonistic genetic programs underlying gonadal sex determination.

CONCLUSION

The results provide new molecular mechanisms leading to the development of the female phenotype in Leydig cells from Insr/Igf1r-DKO mice and could help to better understand the correlation between insulin resistance, testosterone and male (in)fertility.

SOX13 gene downregulation in peripheral blood mononuclear cells of patients with Klinefelter syndrome

Klinefelter syndrome (KS) is the most common sex chromosome disorder in men. It is characterized by germ cell loss and other variable clinical features, including autoimmunity. The sex-determining region of Y (SRY)-box 13 (Sox13) gene is expressed in mouse spermatogonia. In addition, it has been identified as islet cell autoantigen 12 (ICA12), which is involved in the pathogenesis of autoimmune diseases, including type 1 diabetes mellitus (DM) and primary biliary cirrhosis. Sox13 expression has never been investigated in patients with KS. In this age-matched, case-control study performed on ten patients with KS and ten controls, we found that SOX13 is significantly downregulated in peripheral blood mononuclear cells of patients with KS compared to controls. This finding might be consistent with the germ cell loss typical of patients with KS. However, the role of Sox13 in the pathogenesis of germ cell loss and humoral autoimmunity in patients with KS deserves to be further explored.

Characterization of rodent Sertoli cell primary cultures

Sertoli cells play a vital role in spermatogenesis by offering physical and nutritional support to the differentiating male germ cells. They form the blood-testis barrier and secrete growth factors essential for germ cell differentiation. Sertoli cell primary cultures are critical for understanding the regulation of spermatogenesis; however, obtaining pure cultures has been a challenge. Rodent Sertoli cell isolation protocols do not rule out contamination by the interstitial or connective tissue cells. Sertoli cell-specific markers could be helpful, but there is no consensus. Vimentin, the most commonly used marker, is not specific for Sertoli cells since its expression has been reported in peritubular myoid cells, mesenchymal stem cells, fibroblasts, macrophages, and endothelial cells, which contaminate Sertoli cell preparations. Markers based on transcription and growth factors also have limitations. Thus, the impediment to obtaining pure Sertoli cell cultures pertains to both the method of isolation and marker usage. The aim of this review is to discuss improvements to current methods of rodent Sertoli cell primary cultures, assess the properties of prepubertal versus mature Sertoli cell cultures, and propose steps to improve cellular characterization. Potential benefits of using contemporary approaches, including lineage tracing, specific cell ablation, and RNA-seq for obtaining Sertoli-specific transcript markers are discussed. Evaluating the specificity and applicability of these markers at the protein level to characterize Sertoli cells in culture would be critical. This review is expected to positively impact future work using primary cultures of rodent Sertoli cells.

Spermatogenesis is normal in Tex33 knockout mice

Testis expressed gene 33 (Tex33) is a recently reported testis-specific gene and it is evolutionarily conserved in vertebrates. The Tex33 expression is found in cytoplasm of round spermatids in Mus musculus. However, the in vivo function of Tex33 remains unknown. In this study, we made a 62bp in frame deletion on Exon2 of Tex33 gene by CRISPR/Cas9 in C57B/L6 mouse, which cause frame shift mutation of Tex33 gene. Tex33^-/-adult male were fertile, and there is no significant change on litter size compared with male wildtype (Tex33^+/+) adult. Besides, no overt differences were found in testis/body weight ratios, testicular/epididymal tissue morphology, sperm counts, sperm morphology and spermatozoa motility in adult Tex33^-/-male mice (N = 3), in comparison with Tex33^+/+ adult (N = 3). TUNEL assay also indicates the germ cells apoptosis ratio was not significantly changed in adult Tex33^-/- adult male mouse testis (N = 3), compared with adult Tex33^+/+ male (N = 3). Importantly, the first wave of elongating spermatids formation happens in 5w old mice. We find that the first wave of spermiogenesis is not disrupted in both 5-week-old Tex33^+/+ and Tex33^-/-male mouse testes and three hallmarks of spermatogenesis, PLZF,γ-H2AX and TNP1, are all detectable in seminiferous tubule. All results indicate that Tex33 is a redundant gene to spermatogenesis. This study can help other researchers avoid repetitive works on redundant genes.

The transcriptome of the newt Cynops orientalis provides new insights into evolution and function of sexual gene networks in sarcopterygians

Amphibians evolved in the Devonian period about 400 Mya and represent a transition step in tetrapod evolution. Among amphibians, high-throughput sequencing data are very limited for Caudata, due to their largest genome sizes among terrestrial vertebrates. In this paper we present the transcriptome from the fire bellied newt Cynops orientalis. Data here presented display a high level of completeness, comparable to the fully sequenced genomes available from other amphibians. Moreover, this work focused on genes involved in gametogenesis and sexual development. Surprisingly, the gsdf gene was identified for the first time in a tetrapod species, so far known only from bony fish and basal sarcopterygians. Our analysis failed to isolate fgf24 and foxl3, supporting the possible loss of both genes in the common ancestor of Rhipidistians. In Cynops, the expression analysis of genes described to be sex-related in vertebrates singled out an expected functional role for some genes, while others displayed an unforeseen behavior, confirming the high variability of the sex-related pathway in vertebrates.

Testicular expression of long non-coding RNAs is affected by curative GnRHa treatment of cryptorchidism

Background

Cryptorchidism is a frequent endocrinopathy in boys that has been associated with an increased risk of developing testicular cancer and infertility. The condition is curable by combined surgery and hormonal treatment during early pre-pubertal stages using gonadotropin releasing hormone agonist (GnRHa). However, whether the treatment also alters the expression of testicular long non-coding RNAs (lncRNAs) is unknown. To gain insight into the effect of GnRHa on testicular lncRNA levels, we re-analyzed an expression dataset generated from testicular biopsies obtained during orchidopexy for bilateral cryptorchidism.

Results

We identified EGFR-AS1, Linc-ROR, LINC00221, LINC00261, LINC00282, LINC00293, LINC00303, LINC00898, LINC00994, LINC01121, LINC01553, and MTOR-AS1 as potentially relevant for the stimulation of cell proliferation mediated by GnRHa based on their direct or indirect association with rapidly dividing cells in normal and pathological tissues. Surgery alone failed to alter the expression of these transcripts.

Conclusion

Given that lncRNAs can cooperate with chromatin-modifying enzymes to promote epigenetic regulation of genes, GnRHa treatment may act as a surrogate for mini-puberty by triggering the differentiation of Ad spermatogonia via lncRNA-mediated epigenetic effects. Our work provides additional molecular evidence that infertility and azoospermia in cryptorchidism, resulting from defective mini-puberty cannot be cured with successful orchidopexy alone.

Pig Hsd17b3: Alternative splice variants expression, insertion/deletion (indel) in promoter region and their associations with male reproductive traits

Hydroxysteroid 17-Beta Dehydrogenase 3 (Hsd17b3), primarily expressed in Leydig cells (LCs) of the mammalian testes, is essential for testosterone biosynthesis and male fertility. The aim of our study was to profile the expression, splice variants (SV) and novel insertion/deletion (indel) of Hsd17b3 in boars. Quantitative analysis showed that the expression level of Hsd17b3 in the testis was significantly highest. Among different testicular cell types, the Hsd17b3 mRNA expression level of LCs was significantly higher than that of SSCs (spermatogonial stem cells) and SCs (Sertoli cells). Furthermore, the SV was firstly identified in pigs and it was highly expressed in LCs comparing with SSCs and SCs. In addition, two mutations were identified in pig Hsd17b3 gene promotor and intron, respectively, which were associated with male reproductive traits (P <  0.05). In conclusion, both transcripts of Hsd17b3 gene were highly expressed in pig testes and LCs; the two novel indel variants of Hsd17b3 gene can be used as potential DNA makers for the marker-assisted selection in pigs. All these findings would enrich the study of Hsd17b3 gene in pig genetic breeding.

Effects of long term antiprogestine mifepristone (RU486) exposure on sexually dimorphic lncRNA expression and gonadal masculinization in Nile tilapia (Oreochromis niloticus)

Mifepristone (RU486), a clinical abortion agent and potential endocrine disruptor, binds to progestin and glucocorticoid receptors and has multiple functional importance in reproductive physiology. A long-term exposure of RU486 resulted in masculinization of female fish, however, the epigenetic landscape remains elusive. Recent studies demonstrated that long non-coding RNAs (lncRNAs) might play potential roles in epigenetic modulation of sex differentiation, ovarian cancer and germline stem cell survival. To further understand the influence of RU486 exposure on epigenetic regulation, we performed a comparative investigation on sex-biased gonadal lncRNAs profiles using control XX/XY and RU486-induced sex reversed XX Nile tilapia (Oreochromis niloticus) by RNA-seq. In total, 962 sexually differentially expressed lncRNAs and their target genes were screened from the gonads of control and sex reversed fish. In comparison with the control XX group, sex reversal induced by RU486 treatment led to significant up-regulation of 757 lncRNAs and down-regulation of 221 lncRNAs. Hierarchical clustering analysis revealed that global lncRNA expression profiles in RU486-treated XX group clustered into the same branch with the control XY, whereas XX control group formed a separate branch. The KEGG pathway enrichment analysis showed that the cis-target genes between RU486-XX and control-XX were concentrated in NOD - like receptor signaling pathway, Cell adhesion molecules (CAMs) and Biosynthesis of amino acids. Real-time PCR and in situ hybridization experiments demonstrate that lncRNAs showing intense fluctuation during RU486 treatment are also sexually dimorphic during early sex differentiation, which further proves the intimate relationship between lncRNAs and sex differentiation and sexual transdifferentiation. Taken together, our data strongly indicates that a long-term exposure of RU486 resulted in sex reversal of XX female fish and the altered expression of sexually dimorphic lncRNAs might partially account for the sex reversal via epigenetic modification.

Y chromosome loss is associated with age-related male patients with abdominal aortic aneurysms

Purpose

Abdominal aortic aneurysm (AAA) demonstrates many features of autoimmune diseases. Y chromosome, sex-determining region of the Y chromosome (SRY) gene, androgen receptor (AR) gene, and androgen appear as potential candidates for influence of the male immune function. This study investigated Y chromosome numbers, SRY gene, AR gene, and androgen levels in male AAAs. We also investigated the correlation between Y chromosome loss (LOY) ratio, SRY expression, androgen levels, and age.

Patients and methods

We investigated LOY by fluorescence in situ hybridization (FISH) in 37 AAAs and compared with 12 patients with abdominal aortic atherosclerotic occlusive disease (AOD) and 91 healthy controls (HC). We investigated SRY and AR expression at mRNA level by real-time PCR in peripheral T lymphocytes in AAA compared with AOD and HC, and AR protein levels by immunohistochemistry (IHC) in AAA. LOY, SRY expression, androgen levels, and age were examined for correlations using the Spearman’s rank correlation coefficient.

Results

LOY ratio in peripheral T lymphocytes was significantly higher in the AAA group compared with the HC (9.11% vs 5.56%, P<0.001) and AOD groups (9.11% vs 6.42%, P=0.029). The SRY mRNA expression in peripheral T lymphocytes was 4.7-fold lower expressed in the AAA group than in the HC group (P<0.001). Free plasma testosterone levels were lower in the AAA group compared with the HC group (P=0.036), whereas sex hormone-binding globulin levels were higher (P=0.020). LOY ratio and expression of SRY mRNA level increased with age in the AAA group (R=0.402 and, R=0.366, respectively). A significant correlation between AR mRNA level (R=0.692) and aortic diameter was detected. Simultaneously, in AAA tissue, the rate of LOY increased with age (R=0.547) and also positively associated with LOY in peripheral blood T lymphocytes (R=0.661).

Conclusion

This study identified a prominent Y chromosome loss in male AAAs, which is correlated to age, lower level of SRY expression and free testosterone, providing a new clue for the mechanisms of AAA.

Gestational exposure to an epidemiologically defined mixture of phthalates leads to gonadal dysfunction in mouse offspring of both sexes

The increasing concern for the reproductive toxicity of abundantly used phthalates requires reliable tools for exposure risk assessment to mixtures of chemicals, based on real life human exposure and disorder-associated epidemiological evidence. We herein used a mixture of four phthalate monoesters (33% mono-butyl phthalate, 16% mono-benzyl phthalate, 21% mono-ethyl hexyl phthalate, and 30% mono-isononyl phthalate), detected in 1st trimester urine of 194 pregnant women and identified as bad actors for a shorter anogenital distance (AGD) in their baby boys. Mice were treated with 0, 0.26, 2.6 and 13 mg/kg/d of the mixture, corresponding to 0x, 10x, 100x, 500x levels detected in the pregnant women. Adverse outcomes detected in the reproductive system of the offspring in pre-puberty and adulthood included reduced AGD index and gonadal weight, changes in gonadal histology and altered expression of key regulators of gonadal growth and steroidogenesis. Most aberrations were apparent in both sexes, though more pronounced in males, and exhibited a non-monotonic pattern. The phthalate mixture directly affected expression of steroidogenesis as demonstrated in a relevant in vitro model. The detected adversities at exposures close to the levels detected in pregnant women, raise concern on the existing safety limits for early-life human exposures and emphasizes the need for re-evaluation of the exposure risk.

Differential isoform expression and alternative splicing in sex determination in mice

Background

Alternative splicing (AS) may play an important role in gonadal sex determination (GSD) in mammals. The present study was designed to identify differentially expressed isoforms and AS modifications accompanying GSD in mice.

Results

Using deep RNA-sequencing, we performed a transcriptional analysis of XX and XY gonads during sex determination on embryonic days 11 (E11) and 12 (E12). Analysis of differentially expressed genes (DEG) identified hundreds of genes related to GSD and early sex differentiation that may represent good candidates for sex reversal. Expression at time point E11 in males was significantly enriched in RNA splicing and mRNA processing Gene Ontology terms. Differentially expressed isoform analysis identified hundreds of specific isoforms related to GSD, many of which showed no differences in the DEG analysis. Hundreds of AS events were identified as modified at E11 and E12. Female E11 gonads featured sex-biased upregulation of intron retention (in genes related to regulation of transcription, protein phosphorylation, protein transport and mRNA splicing) and exon skipping (in genes related to chromatin repression) suggesting AS as a post-transcription mechanism that controls sex determination of the bipotential fetal gonad.

Conclusion

Our data suggests an important role of splicing regulatory mechanisms for sex determination in mice.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5572-x) contains supplementary material, which is available to authorized users.

A Comparative View on Sex Differentiation and Gametogenesis Genes in Lungfish and Coelacanths

Gonadal sex differentiation and reproduction are the keys to the perpetuation of favorable gene combinations and positively selected traits. In vertebrates, several gonad development features that differentiate tetrapods and fishes are likely to be, at least in part, related to the water-to-land transition. The collection of information from basal sarcopterygians, coelacanths, and lungfishes, is crucial to improve our understanding of the molecular evolution of pathways involved in reproductive functions, since these organisms are generally regarded as “living fossils” and as the direct ancestors of tetrapods. Here, we report for the first time the characterization of >50 genes related to sex differentiation and gametogenesis in Latimeria menadoensis and Protopterus annectens. Although the expression profiles of most genes is consistent with the intermediate position of basal sarcopterygians between actinopterygian fish and tetrapods, their phylogenetic placement and presence/absence patterns often reveal a closer affinity to the tetrapod orthologs. On the other hand, particular genes, for example, the male gonad factor gsdf (Gonadal Soma-Derived Factor), provide examples of ancestral traits shared with actinopterygians, which disappeared in the tetrapod lineage.

Expression profiles of Sox transcription factors within the postnatal rodent testes

SRY-related box (Sox) transcription factors are conserved among vertebrate species. These proteins regulate multiple processes including sex determination and testis differentiation of the male embryo. Members of the Sox family have been identified in pre- and postnatal testis and are known to play an important role in sex determination (Sry, Sox9), male gonadal development, and fertility (Sox4, Sox8, Sox30). However, their expression profiles per cell types remain elusive. The objectives of this research were to characterize the expression profiles of Sox family members within adult testes using publically available datasets and to determine whether these findings are consistent with literature as well as immunofluorescence and in situ hybridization results. We have found that Sox4, Sox8, Sox9, and Sox12 are highly expressed in Sertoli cells, whereas Sox5, Sox6, and Sox30 were typically expressed in spermatocytes and spermatids. Spermatogonia were characterized by the expressions of Sox3, Sox4, Sox12, Sox13, and Sox18. Hence, these results suggest that Sox transcription factors may play different roles according to cell types of the adult mammalian testis.

Sox5 is involved in germ-cell regulation and sex determination in medaka following co-option of nested transposable elements

Background

Sex determination relies on a hierarchically structured network of genes, and is one of the most plastic processes in evolution. The evolution of sex-determining genes within a network, by neo- or sub-functionalization, also requires the regulatory landscape to be rewired to accommodate these novel gene functions. We previously showed that in medaka fish, the regulatory landscape of the master male-determining gene dmrt1bY underwent a profound rearrangement, concomitantly with acquiring a dominant position within the sex-determining network. This rewiring was brought about by the exaptation of a transposable element (TE) called Izanagi, which is co-opted to act as a silencer to turn off the dmrt1bY gene after it performed its function in sex determination.

Results

We now show that a second TE, Rex1, has been incorporated into Izanagi. The insertion of Rex1 brought in a preformed regulatory element for the transcription factor Sox5, which here functions in establishing the temporal and cell-type-specific expression pattern of dmrt1bY. Mutant analysis demonstrates the importance of Sox5 in the gonadal development of medaka, and possibly in mice, in a dmrt1bY-independent manner. Moreover, Sox5 medaka mutants have complete female-to-male sex reversal.

Conclusions

Our work reveals an unexpected complexity in TE-mediated transcriptional rewiring, with the exaptation of a second TE into a network already rewired by a TE. We also show a dual role for Sox5 during sex determination: first, as an evolutionarily conserved regulator of germ-cell number in medaka, and second, by de novo regulation of dmrt1 transcriptional activity during primary sex determination due to exaptation of the Rex1 transposable element.

Electronic supplementary material

The online version of this article (10.1186/s12915-018-0485-8) contains supplementary material, which is available to authorized users.

Identification of Sertoli cell-specific transcripts in the mouse testis and the role of FSH and androgen in the control of Sertoli cell activity

Background

The Sertoli cells act to induce testis differentiation and subsequent development in fetal and post-natal life which makes them key to an understanding of testis biology. As a major step towards characterisation of factors involved in Sertoli cell function we have identified Sertoli cell-specific transcripts in the mouse testis and have used the data to identify Sertoli cell-specific transcripts altered in mice lacking follicle-stimulating hormone receptors (FSHRKO) and/or androgen receptors (AR) in the Sertoli cells (SCARKO).

Results

Adult iDTR mice were injected with busulfan to ablate the germ cells and 50 days later they were treated with diphtheria toxin (DTX) to ablate the Sertoli cells. RNAseq carried out on testes from control, busulfan-treated and busulfan + DTX-treated mice identified 701 Sertoli-specific transcripts and 4302 germ cell-specific transcripts. This data was mapped against results from microarrays using testicular mRNA from 20 day-old FSHRKO, SCARKO and FSHRKO.SCARKO mice. Results show that of the 534 Sertoli cell-specific transcripts present on the gene chips, 85% were altered in the FSHRKO mice and 94% in the SCARKO mice (mostly reduced in both cases). In the FSHRKO.SCARKO mice additive or synergistic effects were seen for most transcripts. Age-dependent studies on a selected number of Sertoli cell-specific transcripts, showed that the marked effects in the FSHRKO at 20 days had largely disappeared by adulthood although synergistic effects of FSHR and AR knockout were seen.

Conclusions

These studies have identified the Sertoli cell-specific transcriptome in the mouse testis and have shown that most genes in the transcriptome are FSH- and androgen-dependent at puberty although the importance of FSH diminishes towards adulthood.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4357-3) contains supplementary material, which is available to authorized users.

Transcription factors SF1 and cJUN cooperate to activate the Fdx1 promoter in MA-10 Leydig cells

The Ferredoxin 1 (FDX1) protein supports steroid biosynthesis in steroidogenic cells through electron transfer to the rate-limiting steroidogenic enzyme, CYP11A1. The latter catalyzes the conversion of cholesterol to pregnenolone through side chain cleavage inside the mitochondria. Thus far, only several transcription factors have been implicated in the regulation of mouse Fdx1 promoter activity in Leydig cells. These include the nuclear receptor SF1 and SP1. Since two conserved regulatory elements for AP1 transcription factors have been located at -764 and -617bp of the Fdx1 promoter, we hypothesized that cJUN may cooperate with other partners to regulate Fdx1 in Leydig cells. Indeed, we report that SF1 and cJUN interact and cooperate to activate the Fdx1 promoter in MA-10 and TM3 Leydig cells. Furthermore, we found that such activation requires different regulatory elements located between -124 and -306bp of the Fdx1 promoter and involves recruitment of SF1 to this region. Using RNA interference, the importance of SF1 in transcriptional regulation of Fdx1 was confirmed, whereas cJUN was dispensable even though it cooperated with SF1 to upregulate Fdx1 expression in MA-10 cells. Thus, our data provides new insights in the molecular mechanisms that control mouse Fdx1 transcription, possibly leading to regulation of CYP11A1 enzyme activation, in Leydig cells.

Steroidogenic genes expressions are repressed by high levels of leptin and the JAK/STAT signaling pathway in MA-10 Leydig cells

The adipose tissue is an important endocrine organ secreting numerous peptide hormones, including leptin. Increased circulating levels of leptin, as a result of hormonal resistance in obese individuals, may contribute to lower androgen production in obese males. However, the molecular mechanisms involved need to be better defined. Androgens are mainly produced by Leydig cells within the testis. In male rodents, activation of the leptin receptor modulates a cascade of intracellular signal transduction pathways which may lead to regulation of transcription factors having influences on steroidogenesis in Leydig cells. Thus, as a result of high leptin levels interacting with its receptor and modulating the activity of the JAK/STAT signaling pathway, the activity of transcription factors important for steroidogenic genes expressions may be inhibited in Leydig cells. Here we show that Lepr is increasingly expressed within Leydig cells according to postnatal development. Although high levels of leptin (corresponding to obesity condition) alone had no effect on Leydig cells' steroidogenic genes expression, it downregulated cAMP-dependent activations of the cholesterol transporter Star and of the rate-limiting steroidogenic enzyme Cyp11a1. Our results suggest that STAT transcriptional activity is downregulated by high levels of leptin, leading to reduced cAMP-dependent steroidogenic genes (Star and Cyp11a1) expressions in MA-10 Leydig cells. However, other transcription factors such as members of the SMAD and NFAT families may be involved and need further investigation to better define how leptin regulates their activities and their relevance for Leydig cells function.

Porcine SOX9 Gene Expression Is Influenced by an 18 bp Indel in the 5'-Untranslated Region

Sex determining region Y-box 9 (SOX9) is an important regulator of sex and skeletal development and is expressed in a variety of embryonal and adult tissues. Loss or gain of function resulting from mutations within the coding region or chromosomal aberrations of the SOX9 locus lead to a plethora of detrimental phenotypes in humans and animals. One of these phenotypes is the so-called male-to-female or female-to-male sex-reversal which has been observed in several mammals including pig, dog, cat, goat, horse, and deer. In 38,XX sex-reversal French Large White pigs, a genome-wide association study suggested SOX9 as the causal gene, although no functional mutations were identified in affected animals. However, besides others an 18bp indel had been detected in the 5′-untranslated region of the SOX9 gene by comparing affected animals and controls. We have identified the same indel (Δ18) between position +247bp and +266bp downstream the transcription start site of the porcine SOX9 gene in four other pig breeds; i.e., German Large White, Laiwu Black, Bamei, and Erhualian. These animals have been genotyped in an attempt to identify candidate genes for porcine inguinal and/or scrotal hernia. Because the 18bp segment in the wild type 5′-UTR harbours a highly conserved cAMP-response element (CRE) half-site, we analysed its role in SOX9 expression in vitro. Competition and immunodepletion electromobility shift assays demonstrate that the CRE half-site is specifically recognized by CREB. Both binding of CREB to the wild type as well as the absence of the CRE half-site in Δ18 reduced expression efficiency in HEK293T, PK–15, and ATDC5 cells significantly. Transfection experiments of wild type and Δ18 SOX9 promoter luciferase constructs show a significant reduction of RNA and protein levels depending on the presence or absence of the 18bp segment. Hence, the data presented here demonstrate that the 18bp indel in the porcine SOX9 5′-UTR is of functional importance and may therefore indeed be a causative variation in SOX9 associated traits.

Is the protein expression window during testicular development affected in patients at risk for stem cell loss?

STUDY QUESTION

Is the protein expression window during testicular development affected in prepubertal patients at risk for stem cell loss?

SUMMARY ANSWER

Nuclear ubiquitin carboxyl-terminal esterase L1 (UCHL1) expression in Sertoli cells and interstitial expression of inhibin α (INHA), sex-determining region Y-box 9 (SOX9) and steroidogenic acute regulatory protein (STAR) was affected in patients with Klinefelter syndrome.

WHAT IS KNOWN ALREADY

Some patients undergoing testicular tissue banking have already been treated before the testis biopsy is taken. These treatments include chemotherapy or hydroxyurea, which can have an influence on the stem cell number and function. A germinal loss occurs in Klinefelter patients, but its cause is currently unknown.

STUDY DESIGN, SIZE, DURATION

Parrafin-embedded testicular tissue from 5 fetuses, 25 prepubertal patients and 5 adults was used to characterize the spatial and temporal distribution of different testicular marker proteins during testicular development. Expression of the markers was evaluated in germ cells, Sertoli cell and interstitial cells. The integrity of this time window was analyzed in patients at risk for germ cell loss: patients treated with hydroxyurea (n = 7), patients treated with chemotherapy (n = 6) and patients affected by Klinefelter syndrome (n = 5).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Immunohistochemistry was performed in normal fetal, prepubertal and adult testicular tissue to set up a timeline for the expression of melanoma antigen family A4 (MAGE-A4), ubiquitin carboxyl-terminal esterase L1 (UCHL1), octamer-binding transcription factor 4 (OCT4), stage-specific embryonic antigen-4 (SSEA4), homeobox protein NANOG, INHA, anti-Müllerian hormone, androgen receptor (AR), SOX9 and STAR. The established timeline was used to evaluate whether the expression of these markers was altered in patients at risk for germ cell loss (patients treated for sickle cell disease (hydroxyurea) or cancer (chemotherapy) and patients with Klinefelter syndrome).

MAIN RESULTS AND THE ROLE OF CHANCE

A protein expression timeline was created using different markers expressed in different testicular cell types. Less positive tubules and less positive cells per tubule were observed for MAGE-A4 and UCHL1 expression in the KS compared with the non-treated group (P < 0.01). Higher nuclear UCHL1 Sertoli cell expression was observed in the KS group compared with the non-treated group (P < 0.05). Higher interstitial expression of INHA (P < 0.05), SOX9 (P < 0.01) and STAR (P < 0.05) was observed in KS compared with the non-treated group.

LIMITATIONS, REASONS FOR CAUTION

Important age variations exist in the prepubertal groups. Therefore, data were represented in three age groups. However, owing to the limited access to prepubertal tissue, no statistical comparison was possible between these groups. For the Klinefelter group, tissue was only available from patients older than 12 years.

WIDER IMPLICATIONS OF THE FINDINGS

The expression timeline can add knowledge to the process of spermatogenesis and be used to evaluate altered protein patterns in patients undergoing potentially gonadotoxic treatments, to monitor spermatogenesis established in vitro and to unravel causes of germ cell loss in Klinefelter patients.