Wnt signaling promotes proliferation and stemness regulation of spermatogonial stem/progenitor cells

The antifibrotic potential of IMT504: modulation of GLAST + Wnt1 + bone marrow stromal progenitors and hepatic microenvironment

BACKGROUND

The immunomodulatory oligodeoxynucleotide (ODN) IMT504 might harbor antifibrotic properties within the liver.

METHODS

Fibrosis models were induced in mice through thioacetamide (TAA) administration and bile-duct ligation. Cre-loxP mice were utilized to identify GLAST + Wnt1 + bone marrow stromal progenitors (BMSPs) and to examine their contribution with cells in the liver. In vivo and in vitro assays; flow-cytometry, immunohistochemistry, and qPCR were conducted.

RESULTS

IMT504 demonstrated significant inhibition of liver fibrogenesis progression and reversal of established fibrosis. Early responses to IMT504 involved the suppression of profibrogenic and proinflammatory markers, coupled with an augmentation of hepatocyte proliferation. Additionally, this ODN stimulated the proliferation and mobilization of GLAST + Wnt1 + BMSPs, likely amplifying their contribution with endothelial- and hepatocytes-like cells. Moreover, IMT504 significantly modulated the expression levels of Wnt ligands and signaling pathway/target genes specifically within GLAST + Wnt1 + BMSPs, with minimal impact on other BMSPs. Intriguingly, both IMT504 and conditioned media from IMT504-pre-treated GLAST + Wnt1 + BMSPs shifted the phenotype of fibrotic macrophages, hepatic stellate cells, and hepatocytes, consistent with the potent antifibrotic effects observed.

CONCLUSION

In summary, our findings identify IMT504 as a promising candidate molecule with potent antifibrotic properties, operating through both direct and indirect mechanisms, including the activation of GLAST + Wnt1 + BMSPs.

PLZF protein forms a complex with protein TET1 to target TCF7L2 in undifferentiated spermatogonia

The transcription factor promyelocytic leukemia zinc finger (PLZF, also known as ZBTB16) is critical for the self-renewal of spermatogonial stem cells (SSCs). However, the function of PLZF in SSCs is not clear. Here, we found that PLZF acted as an epigenetic regulator of stem cell maintenance and self-renewal of germ cells. The PLZF protein interacts with the ten-eleven translocation 1 (TET1) protein and subsequently acts as a modulator to regulate the expression of self-renewal-related genes. Furthermore, Transcription Factor 7-like 2 (TCF7L2) is promoted by the coordination of PLZF and Tri-methylation of lysine 4 on histone H3 (H3K4me3). In addition, testicular single-cell sequencing indicated that TCF7L2 is commonly expressed in the PLZF cluster. We demonstrated that PLZF directly targets TCF7L2 and alters the landscape of histone methylation in the SSCs nucleus. Meanwhile, the RD domain and Zn finger domain of PLZF synergize with H3K4me3 and directly upregulate TCF7L2 expression at the transcriptional level. Additionally, we identified a new association between PLZF and the histone methyltransferase EZH2 at the genomic level. Our study identified a new association between PLZF and H3K4me3, established the novel PLZF&TET1-H3K4me3-TCF7L2 axis at the genomic level which regulates undifferentiated spermatogonia, and provided a platform for studying germ cell development in male domestic animals.

Identification and Analysis of Genes Related to Testicular Size in 14-Day-Old Piglets

The RNA-Seq technology was used to screen the key genes that affect the early development of the testes of Duroc × Landrace × Yorkshire piglets, to determine the regulatory pathway and provide reference for subsequent reproductive performance research, breeding, and other production practices. This study selected 14-day-old Duroc × Landrace × Yorkshire piglets as the trial animals. Testes from piglets with similar weights and no pathological changes were divided into small testis (ST) and large testis (LT) groups, and the RNA-Seq screening of differentially expressed genes (DEGs) was performed to find candidate genes and regulatory pathways related to early testicular development. The results show that 570 DEGs were found in the ST and LT groups, with 281 upregulated and 289 downregulated. The DEGs were mainly enriched on 47 gene ontology (GO) functional items. The Kyoto encyclopedia of genes and genotypes (KEGG) enrichment analysis found that there were 44 significantly enriched KEGG signal pathways, and the regulation of testicular development mainly focused on the arachidonic acid metabolism, Wnt signaling pathway and GnRH secretion pathways. The PTGES, SFRP1, SPP1, PLA2G4E, KCNJ5, PTGS2, and HCN1 genes were found to be as closely related to the testicular development of these Duroc × Landrace × Yorkshire piglets, and the differential gene expression was consistent with the real-time quantitative reverse transcription PCR (real-time qRT-PCR) validation results. This study was validated by high-throughput sequencing analysis and real-time qRT-PCR, and showed that the PTGES, SFRP1, SPP1, PLA2G4E, KCNJ5, PTGS2, and HCN1 genes may be involved in the regulation of germ cell development, spermatogenesis and semen traits. These should be further studied as candidate genes for early testicular development and reproductive trait regulation in boars.

High-content analysis of testicular toxicity of BPA and its selected analogs in mouse spermatogonial, Sertoli cells, and Leydig cells revealed BPAF induced unique multinucleation phenotype associated with the increased DNA synthesis

Bisphenol A is an endocrine disruptor that has been shown to have testicular toxicity in animal models. Its structural analog, including bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) have been introduced to the market as BPA alternatives. Previously, we developed high-content analysis (HCA) assays and applied machine learning to compare the testicular toxicity of BPA and its analogs in spermatogonial cells and testicular cell co-culture models. There are diverse cell populations in the testis to support spermatogenesis, but their cell type-specific toxicities are still not clear. The purpose of this study is to examine the selective toxicity of BPA, BPS), BPAF, and TBBPA on these testicular cells, including Sertoli cells, Leydig cells, and spermatogonia cells. We developed a high-content image-based single-cell analysis and measured a broad spectrum of adverse endpoints related to the development of reproductive toxicology, including cell number, nuclear morphology, DNA synthesis, cell cycle progression, early DNA damage response, cytoskeleton structure, DNA methylation status, and autophagy. We introduced an HCA index and spectrum to reveal multiple HCA parameters and observed distinct toxicity profiling of BPA and its analogs among three testicular types. The HCA spectrum shows the dynamic, chemical-specific, dose-dependent changes of each HCA parameter. Each chemical displayed a unique dose-dependent profile within each type of cell. All three types of cells showed the highest response to BPAF at 10 μM across all endpoints measured. BPAF targeted spermatogonial cell (C18) more significantly at 5 μM. BPS more likely targeted Sertoli cell (TM4) and Leydig cell (TM3) and less at spermatogonia cells. TBBPA targeted spermatogonia, Sertoli cells, and less at TM3 cells. BPA is mainly targeted at TM4, followed by TM3 cells, and less at spermatogonial cells. Most importantly, we observed that BPAF induced a dose-dependent increase in spermatogonia cells, not in Sertoli and Leydig cells. In summary, our current HCA assays revealed the cell-type-specific toxicities of BPA and its analogs in different testicular cells. Multinucleation induced by BPAF, along with increased DNA damage and synthesis at low doses, could possibly have a profound long-term effect on reproductive systems.

BDE-209 disturbed proliferation and differentiation of spermatogonia during mitotic process through estrogen receptor α

Deca-bromodiphenyl ether (BDE-209) exposure caused spermatogenesis disorder resulting in poor sperm quality has become a public concern in recent years. Spermatogenesis refers to the process by which the division of spermatogonia stem cells (SSCs) produces haploid spermatozoa, including mitosis, meiosis, and spermiogenesis. However, the mechanism of mitosis including proliferation and differentiation of spermatogonia dysfunction induced by BDE-209 remains largely unclear. Here, our data showed that BDE-209 exposure caused a decline in sperm quality with seminiferous tubule structure disorder in rats. In addition, BDE-209 exposure damage spermatogonia proliferation and differentiation with decreasing level of PLZF and cKit in testis. Moreover, rats exposed to BDE-209 decreased the expression of ERα, whereas an elevated expression of Wnt3a and Wnt5a. Mechanistically, supplementation with propipyrazole triol (PPT, a selective ERα pathway agonist) rescued sperm quality and attenuated impairment of proliferation and differentiation of spermatogonia in BDE-209-induced rats. Therefore, ERα plays a crucial role in the proliferation and differentiation of spermatogonia during mitotic process. In conclusion, our study clarified the role of ERα in BDE-209-induced spermatogonia proliferation and differentiation in rats and provides a potential therapeutic application on poor sperm quality caused by BDE-209 exposure.

The role of WNT10B in physiology and disease: A 10-year update

WNT10B, a member of the WNT family of secreted glycoproteins, activates the WNT/β-catenin signaling cascade to control proliferation, stemness, pluripotency, and cell fate decisions. WNT10B plays roles in many tissues, including bone, adipocytes, skin, hair, muscle, placenta, and the immune system. Aberrant WNT10B signaling leads to several diseases, such as osteoporosis, obesity, split-hand/foot malformation (SHFM), fibrosis, dental anomalies, and cancer. We reviewed WNT10B a decade ago, and here we provide a comprehensive update to the field. Novel research on WNT10B has expanded to many more tissues and diseases. WNT10B polymorphisms and mutations correlate with many phenotypes, including bone mineral density, obesity, pig litter size, dog elbow dysplasia, and cow body size. In addition, the field has focused on the regulation of WNT10B using upstream mediators, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). We also discussed the therapeutic implications of WNT10B regulation. In summary, research conducted during 2012-2022 revealed several new, diverse functions in the role of WNT10B in physiology and disease.

H3K4me2 cooperates with Wnt/TCF7L2 to regulate TDRD1 and promote chicken spermatogonia stem cell formation

Spermatogonia Stem Cells (SSCs) are the basis of spermatogenesis. In the poultry industry, asthenospermia and azoospermia in roosters seriously reduce economic benefits. In this study, we explored SSCs formation mechanisms in detail. TDRD1, which is a downstream target gene of TCF7L2 and is modified by histone methylation, was screened through multiomics analysis. Functionally, RT-qPCR, flow cytometry, immunohistochemistry, and indirect immunofluorescence results showed that H3K4me2 regulated TDRD1 to promote SSCs formation both in vivo and in vitro. Furthermore, ChIP-qPCR and dual luciferase assays showed that H3K4me2 was enriched in the -800 to 0 bp region of the TDRD1 promoter and positively regulated TDRD1 transcription to promote SSCs formation. Interestingly, in mechanistic terms, dual luciferase assays showed that TDRD1 transcription levels were significantly decreased after co-transfection with dCas9-LSD1-P1/P2/P3 and OETCF7L2, while TDRD1 transcript levels were not significantly altered after transfecting dCas9-LSD1-P4 and OETCF7L2. These results suggested that H3K4me2 enrichment in P1, P2, and P3 of the TDRD1 promoter promotes TDRD1 transcription by reducing enrichment of TCF7L2. This study explored the specific regulatory mechanisms involving the Wnt signaling pathway, H3K4me2, and TDRD1, enriched the regulatory network regulating the formation of SSCs, and laid a theoretical foundation for the specific application of SSCs.

Transcriptome sequencing reveals the effects of circRNA on testicular development and spermatogenesis in Qianbei Ma goats

Circular RNAs (circRNAs) play an important role in regulating the mammalian reproductive system, especially testicular development and spermatogenesis. However, their functions in testicular development and spermatogenesis in the Qianbei Ma goat, the Guizhou endemic breed are still unclear. In this study, tissue sectioning and circRNAs transcriptome analysis were conducted to compare the changes of morphology and circular RNAs gene expression profile at four different developmental stages (0Y, 0-month-old; 6Y, 6-month-old; 12Y, 12-month-old; 18Y, 18-month-old). The results showed that the circumferences and area of the seminiferous tubule gradually increased with age, and the lumen of the seminiferous tubule in the testis differentiated significantly. 12,784 circRNAs were detected from testicular tissues at four different developmental stages by RNA sequencing, and 8,140 DEcircRNAs (differentially expressed circRNAs) were found in 0Y vs. 6Y, 6Y vs. 12Y, 12Y vs. 18Y and 0Y vs. 18Y, 0Y vs. 12Y, 6Y vs. 18Y Functional enrichment analysis of the source genes showed that they were mainly enriched in testicular development and spermatogenesis. In addition, the miRNAs and mRNAs associated with DECircRNAs in 6 control groups were predicted by bioinformatics, and 81 highly expressed DECircRNAs and their associated miRNAs and mRNAs were selected to construct the ceRNA network. Through functional enrichment analysis of the target genes of circRNAs in the network, some candidate circRNAs related to testicular development and spermatogenesis were obtained. Such as circRNA_07172, circRNA_04859, circRNA_07832, circRNA_00032 and circRNA_07510. These results will help to reveal the mechanism of circRNAs in testicular development and spermatogenesis, and also provide some guidance for goat reproduction.

Dynamic transcriptome analysis reveals the gene network of gonadal development from the early history life stages in dwarf surfclam Mulinia lateralis

BACKGROUND

Gonadal development is driven by a complex genetic cascade in vertebrates. However, related information remains limited in molluscs owing to the long generation time and the difficulty in maintaining whole life cycle in the lab. The dwarf surfclam Mulinia lateralis is considered an ideal bivalve model due to the short generation time and ease to breed in the lab.

RESULTS

To gain a comprehensive understanding of gonadal development in M. lateralis, we conducted a combined morphological and molecular analysis on the gonads of 30 to 60 dpf. Morphological analysis showed that gonad formation and sex differentiation occur at 35 and 40-45 dpf, respectively; then the gonads go through gametogenic cycle. Gene co-expression network analysis on 40 transcriptomes of 35-60 dpf gonads identifies seven gonadal development-related modules, including two gonad-forming modules (M6, M7), three sex-specific modules (M14, M12, M11), and two sexually shared modules (M15, M13). The modules participate in different biological processes, such as cell communication, glycan biosynthesis, cell cycle, and ribosome biogenesis. Several hub transcription factors including SOX2, FOXZ, HSFY, FOXL2 and HES1 are identified. The expression of top hub genes from sex-specific modules suggests molecular sex differentiation (35 dpf) occurs earlier than morphological sex differentiation (40-45 dpf).

CONCLUSION

This study provides a deep insight into the molecular basis of gonad formation, sex differentiation and gametogenesis in M. lateralis, which will contribute to a comprehensive understanding of the reproductive regulation network in molluscs.

A homozygous PIWIL2 frameshift variant affects the formation and maintenance of human-induced pluripotent stem cell-derived spermatogonial stem cells and causes Sertoli cell-only syndrome

Background

The most serious condition of male infertility is complete Sertoli cell-only syndrome (SCOS), which refers to the lack of all spermatogenic cells in the testes. The genetic cause of SCOS remains to be explored. We aimed to investigate the genetic cause of SCOS and assess the effects of the identified causative variant on human male germ cells.

Methods

Whole-exome sequencing was performed to identify potentially pathogenic variants in a man with complete SCOS, and Sanger sequencing was performed to verify the causative variant in this man and his father and brother. The pathogenic mechanisms of the causative variant were investigated by in vitro differentiation of human-induced pluripotent stem cells (hiPSCs) into germ cell-like cells.

Results

The homozygous loss-of-function (LoF) variant p.His244ArgfsTer31 (c.731_732delAT) in PIWIL2 was identified as the causative variant in the man with complete SCOS, and the same variant in heterozygosis was confirmed in his father and brother. This variant resulted in a truncated PIWIL2 protein lacking all functional domains, and no PIWIL2 expression was detected in the patient’s testes. The patient and PIWIL2^−/− hiPSCs could be differentiated into primordial germ cell-like cells and spermatogonial stem cell-like cells (SSCLCs) in vitro, but the formation and maintenance of SSCLCs were severely impaired. RNA-seq analyses suggested the inactivation of the Wnt signaling pathway in the process of SSCLC induction in the PIWIL2^−/− group, which was validated in the patient group by RT-qPCR. The Wnt signaling pathway inhibitor hindered the formation and maintenance of SSCLCs during the differentiation of normal hiPSCs.

Conclusions

Our study revealed the pivotal role of PIWIL2 in the formation and maintenance of human spermatogonial stem cells. We provided clinical and functional evidence that the LoF variant in PIWIL2 is a genetic cause of SCOS, which supported the potential role of PIWIL2 in genetic diagnosis. Furthermore, our results highlighted the applicability of in vitro differentiation models to function validation experiments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03175-6.

Two Short Repeats in the 5′ Untranslated Region of Insulin-like Androgenic Gland Factor in Procambarus clarkii (PcIAG) That Regulate PcIAG Expression

Insulin-like androgenic gland factor (IAG) plays an important role in sex manipulation in decapods. Understanding the molecular regulation mechanism of IAG in Procambarus clarkii (PcIAG) is important for realizing its sex control. In this study, the promoter and gene structure of PcIAG, mRNA, and miRNA expression profiles after interfering with two siRNAs synthesized according to the two short repeats in the 5′ untranslated regions (5′UTR) of PcIAG were analyzed, and miRNAs of exosomes were investigated to explore the role of repeated sequences with tandem two short repeats located in the 5′UTR of PcIAG isolated from the androgenic gland (AG) in the regulation of IAG expression. The results showed that the repeated sequences of 5′UTR only occurred completely in the cDNA from AG, and the function of the two repeats was different in regulating the expression of PcIAG, in which the Wnt signaling pathway may be involved. Furthermore, we found that six miRNAs including miR-133, miR-193, miR-34, miR-1, miR-100, and let-7 might be involved in the regulation of the expression of PcIAG, wherein miR-133 might directly be related with the repeated sequences of 5′UTR.

SAT2 regulates Sertoli cell-germline interactions via STIM1-mediated ROS/WNT/β-catenin signaling pathway

As the main component of seminiferous tubules, Sertoli cells are in close contact with germ cells and generate niche signals, which exhibit pivotal functions in spermatogenesis and male fertility. However, the regulatory mechanisms of Sertoli cell-germline interactions (SGIs) in the testes of neonatal mice (NM) remain largely unclear. Previously, we identified spermidine/spermine N1-acetyl transferase 2 (SAT2) and stromal interaction molecule 1 (STIM1) to be potential regulators of testicular cord formation via comparative proteomics analysis. Here, we demonstrated a novel role of SAT2 for SGIs during testicular development in NM. Testicular explants lacking SAT2 affected the mislocation, but not the quantity, of Sertoli cells, which led to maintenance defects in spermatogonial stem cells (SSCs). Interestingly, SAT2 was essential for the migration of TM4 cells, a Sertoli cell line. Mechanistically, SAT2 was able to bind STIM1, repress its expression, and regulate homeostasis of a reactive oxygen species/wingless type (WNT)/β-catenin pathway in NM testes. Collectively, our study identified that SAT2 was able to regulate SGIs via a STIM1-mediated WNT signaling pathway.

Comparison of miRNA and mRNA Expression in Sika Deer Testes With Age

To elucidate the complex physiological process of testis development and spermatogenesis in Sika deer, this study evaluated the changes of miRNA and mRNA profiles in the four developmental stages of testis in the juvenile (1-year-old), adolescence (3-year-old), adult (5-year-old), and aged (10-year-old) stages. The results showed that a total of 198 mature, 66 novel miRNAs, and 23,558 differentially expressed (DE) unigenes were obtained; 14,918 (8,413 up and 6,505 down), 4,988 (2,453 up and 2,535 down), and 5,681 (2,929 up and 2,752 down) DE unigenes, as well as 88 (43 up and 45 down), 102 (44 up and 58 down), and 54 (18 up and 36 down) DE miRNAs were identified in 3- vs. 1-, 5- vs. 3-, and 10- vs. 5-year-old testes, respectively. By integrating miRNA and mRNA expression profiles, we predicted 10,790 mRNA-mRNA and 69,883 miRNA-mRNA interaction sites. The target genes were enriched by GO and KEGG pathways to obtain DE mRNA (IGF1R, ALKBH5, Piwil, HIF1A, BRDT, etc.) and DE miRNA (miR-140, miR-145, miR-7, miR-26a, etc.), which play an important role in testis development and spermatogenesis. The data show that DE miRNAs could regulate testis developmental and spermatogenesis through signaling pathways, including the MAPK signaling pathway, p53 signaling pathway, PI3K-Akt signaling pathway, Hippo signaling pathway, etc. miR-140 was confirmed to directly target mutant IGF1R-3'UTR by the Luciferase reporter assays. This study provides a useful resource for future studies on the role of miRNA regulation in testis development and spermatogenesis.

Sertoli Cell-Germ Cell Interactions Within the Niche: Paracrine and Juxtacrine Molecular Communications

Male germ cell development depends on multiple biological events that combine epigenetic reprogramming, cell cycle regulation, and cell migration in a spatio-temporal manner. Sertoli cells are a crucial component of the spermatogonial stem cell niche and provide essential growth factors and chemokines to developing germ cells. This review focuses mainly on the activation of master regulators of the niche in Sertoli cells and their targets, as well as on novel molecular mechanisms underlying the regulation of growth and differentiation factors such as GDNF and retinoic acid by NOTCH signaling and other pathways.

Breathe it in - Spotlight on senescence and regeneration in the lung

Cellular senescence, a highly coordinated and programmed cellular state, has a functional role in both lung physiology and pathology. While the contribution of senescent cells is recognized in the context of ageing and age-related pulmonary diseases, relatively less is known how cellular senescence of functionally distinct cell types leads to the progression of these pathologies. Recent advances in tools to track and isolate senescent cells from tissues, shed a light on the identity, behavior and function of senescent cells in vivo. The transient presence of senescent cells has an indispensable role in limiting lung damage and contributes to organ regenerative capacity upon acute stress insults. In contrast, persistent accumulation of senescent cells is a driver of age-related decline in organ function. Here, we discuss lung physiology and pathology as an example of seemingly contradictory role of senescence in structural and functional integrity of the tissue upon damage, and in age-related pulmonary diseases.

Identification and Characterization of lncRNA and mRNA in Testes of Landrace and Hezuo Boars

Simple Summary

Precocious puberty is an excellent reproductive trait in domestic animals, which can generate higher breeding benefits in livestock production. However, regulators associated with this sexual maturation process remain largely unknown. Chinese Hezuo (HZ) boars are known for their early sexual maturity. In this work, the characteristics of precocious puberty in HZ pigs were confirmed by histological analysis, and some important long noncoding RNA (lncRNA) and mRNA were identified in the testes of immature (30-day-old) and mature (120-day-old) HZ boars, which could play a key role in precocious puberty. These results will provide a theoretical basis for further research on the regulatory mechanism of precocious puberty, which is important for accelerating the breeding process of highly fertile animals.

Abstract

Chinese HZ boars are typical plateau miniature boars characterized by precocious puberty, which is closely related to testicular development and spermatogenesis. Accumulating evidence indicates that lncRNA is involved in the testicular development and regulation of spermatogenesis. However, little is known about the lncRNA precocious regulation in testicular development and spermatogenesis on early sexual maturity of HZ boars. Thus, we investigated the expression and characterization of lncRNA and mRNA in 30-day-old and 120-day-old HZ boar testes using transcriptome to explore precocious puberty. Landrace (LC) boar was treated as the control. Histological analyses indicated that HZ boar underwent puberty development at an earlier stage than LC boar and had achieved sexual maturity at 120 days old. RNA-Seq yielded a total of 187 lncRNAs and 984 mRNAs; these molecules were identified as possible candidates for precocious puberty. GO terms and KEGG pathways enrichment analyses revealed that the differentially expressed lncRNA and their targeted genes were involved in metabolic pathways regulating testis development and spermatogenesis, such as the PI3K-Akt, TGF-beta and Wnt pathways. Further screening, some lncRNA (such as LOC102166140, LOC110259451, and MSTRG.15011.2), and mRNA (such as PDCL2, HSD17B4, SHCBP1L, CYP21A2, and SPATA3) were found to be possibly associated with precocious puberty, which would add to our understanding of the molecular regulatory mechanisms of precocious puberty. This study provided valuable information for further study of the role of lncRNA and mRNA in the process of precocious puberty.

POSTN Promotes the Proliferation of Spermatogonial Cells by Activating the Wnt/β-Catenin Signaling Pathway

The self-renewal of spermatogonial cells (SCs) provides the foundation for life-long spermatogenesis. To date, only a few growth factors have been used for the culture of SCs in vitro, and how to enhance proliferation capacity of SCs in vitro needs further research. This study aimed to explore the effects of periostin (POSTN) on the proliferation of human SCs. GC-1 spg cells were cultured in a medium with POSTN, cell proliferation was evaluated by MTS analysis and EdU assay, and the Wnt/β-catenin signaling pathway was examined. Thereafter, the proliferations of human SC were detected using immunofluorescence and RT-PCR. In this study, we found that CM secreted by human amniotic mesenchymal stem cells (hAMSCs) could enhance the proliferation capacity of mouse GC-1 spg cells. Label-free mass spectrometry and ELISA analysis demonstrated that high level of POSTN was secreted by hAMSCs. MTS and EdU staining showed that POSTN increased GC-1 spg cell proliferation, whereas CM from POSTN-silenced hAMSCs suppressed cell proliferation capacity. Then POSTN was found to activate the Wnt/β-catenin signaling pathway to regulate the proliferation of GC-1 spg cells. XAV-939, a Wnt/β-catenin inhibitor, partially reversed the effects of POSTN on GC-1 spg cell proliferation. We then analyzed human SCs and found that POSTN promoted human SC proliferation in vitro. These findings provide insights regarding the role of POSTN in regulating SC proliferation via the Wnt/β-catenin signaling pathway and suggest that POSTN may serve as a cytokine for male infertility therapy.

WNT signalling in the normal human adult testis and in male germ cell neoplasms

STUDY QUESTION

Is WNT signalling functional in normal and/or neoplastic human male germ cells?

SUMMARY ANSWER

Regulated WNT signalling component synthesis in human testes indicates that WNT pathway function changes during normal spermatogenesis and is active in testicular germ cell tumours (TGCTs), and that WNT pathway blockade may restrict seminoma growth and migration.

WHAT IS KNOWN ALREADY

Regulated WNT signalling governs many developmental processes, including those affecting male fertility during early germ cell development at embryonic and adult (spermatogonial) ages in mice. In addition, although many cancers arise from WNT signalling alterations, the functional relevance and WNT pathway components in TGCT, including germ cell neoplasia in situ (GCNIS), are unknown.

STUDY DESIGN, SIZE, DURATION

The cellular distribution of transcripts and proteins in WNT signalling pathways was assessed in fixed human testis sections with normal spermatogenesis, GCNIS and seminoma (2-16 individuals per condition). Short-term (1-7 h) ligand activation and long-term (1-5 days) functional outcomes were examined using the well-characterised seminoma cell line, TCam-2. Pathway inhibition used siRNA or chemical exposures over 5 days to assess survival and migration.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The cellular localisation of WNT signalling components was determined using in situ hybridisation and immunohistochemistry on Bouin's- and formalin-fixed human testis sections with complete spermatogenesis or germ cell neoplasia, and was also assessed in TCam-2 cells. Pathway function tests included exposure of TCam-2 cells to ligands, small molecules and siRNAs. Outcomes were measured by monitoring beta-catenin (CTNNB1) intracellular localisation, cell counting and gap closure measurements.

MAIN RESULTS AND THE ROLE OF CHANCE

Detection of nuclear-localised beta-catenin (CTNNB1), and key WNT signalling components (including WNT3A, AXIN2, TCF7L1 and TCF7L2) indicate dynamic and cell-specific pathway activity in the adult human testis. Their presence in germ cell neoplasia and functional analyses in TCam-2 cells indicate roles for active canonical WNT signalling in TGCT relating to viability and migration. All data were analysed to determine statistical significance.

LARGE SCALE DATA

No large-scale datasets were generated in this study.

LIMITATIONS, REASONS FOR CAUTION

As TGCTs are rare and morphologically heterogeneous, functional studies in primary cancer cells were not performed. Functional analysis was performed with the only well-characterised, widely accepted seminoma-derived cell line.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrated the potential sites and involvement of the WNT pathway in human spermatogenesis, revealing similarities with murine testis that suggest the potential for functional conservation during normal spermatogenesis. Evidence that inhibition of canonical WNT signalling leads to loss of viability and migratory activity in seminoma cells suggests that potential treatments using small molecule or siRNA inhibitors may be suitable for patients with metastatic TGCTs.

STUDY FUNDING AND COMPETING INTEREST(S)

This study was funded by National Health and Medical Research Council of Australia (Project ID 1011340 to K.L.L. and H.E.A., and Fellowship ID 1079646 to K.L.L.) and supported by the Victorian Government's Operational Infrastructure Support Program. None of the authors have any competing interests.

Arid1a-Plagl1-Hh signaling is indispensable for differentiation-associated cell cycle arrest of tooth root progenitors

Chromatin remodelers often show broad expression patterns in multiple cell types yet can elicit cell-specific effects in development and diseases. Arid1a binds DNA and regulates gene expression during tissue development and homeostasis. However, it is unclear how Arid1a achieves its functional specificity in regulating progenitor cells. Using the tooth root as a model, we show that loss of Arid1a impairs the differentiation-associated cell cycle arrest of tooth root progenitors through Hedgehog (Hh) signaling regulation, leading to shortened roots. Our data suggest that Plagl1, as a co-factor, endows Arid1a with its cell-type/spatial functional specificity. Furthermore, we show that loss of Arid1a leads to increased expression of Arid1b, which is also indispensable for odontoblast differentiation but is not involved in regulation of Hh signaling. This study expands our knowledge of the intricate interactions among chromatin remodelers, transcription factors, and signaling molecules during progenitor cell fate determination and lineage commitment.

Transcriptome analysis revealed differences in the microenvironment of spermatogonial stem cells in seminiferous tubules between pre-pubertal and adult buffaloes

The microenvironment in the seminiferous tubules of buffalo changes with age, which affects the self-renewal and growth of spermatogonial stem cells (SSCs) and the process of spermatogenesis, but the mechanism remains to be elucidated. RNA-seq was performed to compare the transcript profiles of pre-pubertal buffalo (PUB) and adult buffalo (ADU) seminiferous tubules. In total, 17,299 genes from PUB and ADU seminiferous tubules identified through RNA-seq, among which 12,271 were expressed in PUB and ADU seminiferous tubules, 4,027 were expressed in only ADU seminiferous tubules, and 956 were expressed in only PUB seminiferous tubules. Of the 17,299 genes, we identified 13,714 genes that had significant differences in expression levels between PUB and ADU through GO enrichment analysis. Among these genes, 5,342 were significantly upregulated and possibly related to the formation or identity of the surface antigen on SSCs during self-renewal; 7,832 genes were significantly downregulated, indicating that genes in PUB seminiferous tubules do not participate in the biological processes of sperm differentiation or formation in this phase compared with those in ADU seminiferous tubules. Subsequently, through the combination with KEGG analysis, we detected enrichment in a number of genes related to the development of spermatogonial stem cells, providing a reference for study of the development mechanism of buffalo spermatogonial stem cells in the future. In conclusion, our data provide detailed information on the mRNA transcriptomes in PUB and ADU seminiferous tubules, revealing the crucial factors involved in maintaining the microenvironment and providing a reference for further in vitro cultivation of SSCs.

The role of Wnt signaling in male reproductive physiology and pathology

Accumulating evidence has shown that Wnt signaling is deeply involved in male reproductive physiology, and malfunction of the signal path can cause pathological changes in genital organs and sperm cells. These abnormalities are diverse in manifestation and have been constantly found in the knockout models of Wnt studies. Nevertheless, most of the research solely focused on a certain factor in the Wnt pathway, and there are few reports on the overall relation between Wnt signals and male reproductive physiology. In our review, Wnt findings relating to the reproductive system were sought and summarized in terms of Wnt ligands, Wnt receptors, Wnt intracellular signals and Wnt regulators. By sorting out and integrating relevant functions, as well as underlining the controversies among different reports, our review aims to offer an overview of Wnt signaling in male reproductive physiology and pathology for further mechanistic studies.

Microarray analysis identification of key pathways and interaction network of differential gene expressions during osteogenic differentiation

BACKGROUND

Adult bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stem cells that can differentiate into three lineages. They are suitable sources for cell-based therapy and regenerative medicine applications. This study aims to evaluate the hub genes and key pathways of differentially expressed genes (DEGs) related to osteogenesis by bioinformatics analysis in three different days. The DEGs were derived from the three different days compared with day 0.

RESULTS

Gene expression profiles of GSE37558 were obtained from the Gene Expression Omnibus (GEO) database. A total of 4076 DEGs were acquired on days 8, 12, and 25. Gene ontology (GO) enrichment analysis showed that the non-canonical Wnt signaling pathway and lipopolysaccharide (LPS)-mediated signaling pathway were commonly upregulated DEGs for all 3 days. KEGG pathway analysis indicated that the PI3K-Akt and focal adhesion were also commonly upregulated DEGs for all 3 days. Ten hub genes were identified by CytoHubba on days 8, 12, and 25. Then, we focused on the association of these hub genes with the Wnt pathways that had been enriched from the protein-protein interaction (PPI) by the Cytoscape plugin MCODE.

CONCLUSIONS

These findings suggested further insights into the roles of the PI3K/AKT and Wnt pathways and their association with osteogenesis. In addition, the stem cell microenvironment via growth factors, extracellular matrix (ECM), IGF1, IGF2, LPS, and Wnt most likely affect osteogenesis by PI3K/AKT.

The effect of regulating the Wnt signaling pathway on the proliferation and differentiation of spermatogonial stem cells

Background

Spermatogonial stem cells and organ engineering research has raised new hope in infertility treatment. Spermatogenesis is a complex physiological process. To observe the proliferation ability and differentiation tendency of mice spermatogonial stem cells (SSCs), to study the effect of regulating the Wnt signaling pathway on the proliferation and differentiation of SSCs, and to provide a valuable basis for the clinical application of SSCs.

Methods

SSCs were isolated and cultured by immunomagnetic separation. Cell surface markers were identified by flow cytometry. Axin1 was chosen as the target gene to inhibit fibrosis of SSCs by inhibiting the activity of Wnt signaling pathway. Axin-siRNA interference vector was constructed and transfected into spermatogonial stem cells. Cultured SSCs were randomly divided into six groups: control group, SSCs + TGF-β group, SSCs + DKK1 group, SSCs + Axin-RNAi group, SSCs + TGF-β + DKK1 group, SSCs + TGF-β + Axin-RNAi group. Proliferation of SSCs in each group was detected by MTT assay. Immunofluorescence, western blot and real time polymerase chain reaction analysis were used to detect protein expression in the Wnt/β catenin signaling pathways and the molecular markers of fibroblasts in SSCs.

Results

Flow cytometry analysis confirmed that the cultured SSCs were of high purity. MTT assay showed there was no significant difference between Axin-siRNA transfected and non-transfected cells. The proliferation ability was significantly increased in the SSCs + TGF-β group, however, it was retarded in SSCs + Axin-RNAi group. The results of immunofluorescence and western blot analysis showed that the expression levels of the Wnt signaling pathway proteins were relatively inhibited after Axin-siRNA was applied. Real-time polymerase chain reaction showed that the expression levels of the molecular markers of fibroblasts were close to the normal control group.

Conclusions

The Axin-siRNA constructed in this study specifically inhibited Wnt/β-catenin signal pathway activation, then inhibited the differentiation of SSCs into fibroblasts, which provides a valuable basis for the clinical application of SSCs.

Cracd Marks the First Wave of Meiosis during Spermatogenesis and Is Mis-Expressed in Azoospermia Mice

Testicular development starts in utero and maturation continues postnatally, requiring a cascade of gene activation and differentiation into different cell types, with each cell type having its own specific function. As we had previously reported that the Capping protein inhibiting regulator of actin (Cracd) gene was expressed in the adult mouse testis, herein we examine when and where the β-catenin associated Cracd is initially expressed during postnatal testis development. Significantly, Cracd mRNA is present in both the immature postnatal and adult testis in round spermatid cells, with highest level of expression occurring during the first wave of meiosis and spermatogenesis. In the juvenile testes, Cracd is initially expressed within the innermost region but as maturation occurs, Cracd mRNA switches to a more peripheral location. Thereafter, Cracd is downregulated to maintenance levels in the haploid male germ cell lineage. As Cracd mRNA was expressed within developing round spermatids, we tested its effectiveness as a biomarker of non-obstructive azoospermia using transgenic knockout mice models. Meaningfully, Cracd expression was absent in Deleted in azoospermia like (Dazl) null testis, which exhibit a dramatic germ cell loss. Moreover, Cracd was abnormally regulated and ectopically mis-expressed in Polypyrimidine tract binding protein-2 (Ptbp2) conditional germ cell restricted knockout testis, which exhibit a block during spermatid differentiation and a reduction in the number of late stage spermatocytes coincident with reduced β-catenin expression. Combined, these data suggest that Cracd is a useful first wave of spermatogenesis biomarker of azoospermia phenotypes, even prior to an overt phenotype being evident.

Conversion from spermatogonia to spermatocytes: Extracellular cues and downstream transcription network

Spermatocyte (spc) formation from spermatogonia (spg) differentiation is the first step of spermatogenesis which produces prodigious spermatozoa for a lifetime. After decades of studies, several factors involved in the functioning of a mouse were discovered both inside and outside spg. Considering the peculiar expression and working pattern of each factor, this review divides the whole conversion of spg to spc into four consecutive development processes with a focus on extracellular cues and downstream transcription network in each one. Potential coordination among Dmrt1, Sohlh1/2 and BMP families mediates Ngn3 upregulation, which marks progenitor spg, with other changes. After that, retinoic acid (RA), as a master regulator, promotes A1 spg formation with its helpers and Sall4. A1-to-B spg transition is under the control of Kitl and impulsive RA signaling together with early and late transcription factors Stra8 and Dmrt6. Finally, RA and its responsive effectors conduct the entry into meiosis. The systematic transcription network from outside to inside still needs research to supplement or settle the controversials in each process. As a step further ahead, this review provides possible drug targets for infertility therapy by cross-linking humans and mouse model.

Formation of organotypic testicular organoids in microwell culture†

Three-dimensional (3D) organoids can serve as an in vitro platform to study cell-cell interactions, tissue development, and toxicology. Development of organoids with tissue architecture similar to testis in vivo has remained a challenge. Here, we present a microwell aggregation approach to establish multicellular 3D testicular organoids from pig, mouse, macaque, and human. The organoids consist of germ cells, Sertoli cells, Leydig cells, and peritubular myoid cells forming a distinct seminiferous epithelium and interstitial compartment separated by a basement membrane. Sertoli cells in the organoids express tight junction proteins claudin 11 and occludin. Germ cells in organoids showed an attenuated response to retinoic acid compared to germ cells in 2D culture indicating that the tissue architecture of the organoid modulates response to retinoic acid similar to in vivo. Germ cells maintaining physiological cell-cell interactions in organoids also had lower levels of autophagy indicating lower levels of cellular stress. When organoids were treated with mono(2-ethylhexyl) phthalate (MEHP), levels of germ cell autophagy increased in a dose-dependent manner, indicating the utility of the organoids for toxicity screening. Ablation of primary cilia on testicular somatic cells inhibited the formation of organoids demonstrating an application to screen for factors affecting testicular morphogenesis. Organoids can be generated from cryopreserved testis cells and preserved by vitrification. Taken together, the testicular organoid system recapitulates the 3D organization of the mammalian testis and provides an in vitro platform for studying germ cell function, testicular development, and drug toxicity in a cellular context representative of the testis in vivo.

Short time exposure to low concentration of zinc oxide nanoparticles up-regulates self-renewal and spermatogenesis-related gene expression

Extensive application of zinc oxide (ZnO) nanoparticles (NPs) in everyday life results in increased exposure to these NPs. Spermatogonial stem cells (SSCs) guarantee sperm production throughout the male reproductive life by providing a balance between self-renewal and differentiation. We used an in vitro platform to investigate the ZnO NPs effects on SSCs. We successfully synthesized ZnO NPs. In order to investigate these NPs, we isolated SSCs from mouse testes and cultured them in vitro. Our results confirmed the uptake of ZnO NPs by the cultured SSCs. We observed a dose- and time-dependent decrease in SSC viability. Both spherical and nanosheet ZnO NPs had the same cytotoxic effects on the SSCs, irrespective of their shapes. Moreover, we have shown that short time (one day) exposure of SSCs to a low concentration of ZnO NPs (10 μg/mL) promoted expressions of specific genes (Plzf, Gfr α1 and Bcl6b) for SSC self-renewal and differentiation genes (Vasa, Dazl, C-kit and Sycp3) expressed by spermatogonia during spermatogenesis. Our study provides the first insight into ZnO NPs function in SSCs and suggests a new function for ZnO NPs in the male reproductive system. We demonstrated that ZnO NPs might promote spermatogenesis via upregulation of gene expression related to SSC self-renewal and differentiation at low concentrations. Additional research should clarify the possible effect of ZnO NPs on the SSC genome and its effects on human SSCs.

Signaling Inhibitors Accelerate the Conversion of mouse iPS Cells into Cancer Stem Cells in the Tumor Microenvironment

Cancer stem cells (CSCs) are a class of cancer cells characterized by self-renewal, differentiation and tumorigenic potential. We previously established a model of CSCs by culturing mouse induced pluripotent stem cells (miPSCs) for four weeks in the presence of a conditioned medium (CM) of cancer cell lines, which functioned as the tumor microenvironment. Based on this methodology of developing CSCs from miPSCs, we assessed the risk of 110 non-mutagenic chemical compounds, most of which are known as inhibitors of cytoplasmic signaling pathways, as potential carcinogens. We treated miPSCs with each compound for one week in the presence of a CM of Lewis lung carcinoma (LLC) cells. However, one-week period was too short for the CM to convert miPSCs into CSCs. Consequently, PDO325901 (MEK inhibitor), CHIR99021 (GSK-3β inhibitor) and Dasatinib (Abl, Src and c-Kit inhibitor) were found to confer miPSCs with the CSC phenotype in one week. The tumor cells that survived exhibited stemness markers, spheroid formation and tumorigenesis in Balb/c nude mice. Hence, we concluded that the three signal inhibitors accelerated the conversion of miPSCs into CSCs. Similarly to our previous study, we found that the PI3K-Akt signaling pathway was upregulated in the CSCs. Herein, we focused on the expression of relative genes after the treatment with these three inhibitors. Our results demonstrated an increased expression of pik3ca, pik3cb, pik3r5 and pik3r1 genes indicating class IA PI3K as the responsible signaling pathway. Hence, AKT phosphorylation was found to be up-regulated in the obtained CSCs. Inhibition of Erk1/2, tyrosine kinase, and/or GSK-3β was implied to be involved in the enhancement of the PI3K-AKT signaling pathway in the undifferentiated cells, resulting in the sustained stemness, and subsequent conversion of miPSCs into CSCs in the tumor microenvironment.

The role of CTNNB1 and LEF1 in feather follicles development of Anser cygnoides and Anser anser

BACKGROUND

Wingless-types/beta-catenin (Wnt/β-catenin) signaling pathway is one of the most extensively studied transcriptional cascades involved in various types of organogenesis including embryonic and postnatal development. Downy feather quantity is primarily affected by follicular development and gene regulations.

OBJECTIVE

This research was aimed to investigate the role of catenin beta-1(CTNNB1) and lymphoid enhancerbinding factor-1 (LEF1) on feather follicles development at different developmental stages.

METHODS

Fluorescence quantitative PCR, Western-blot and immunohistochemical methods were used in Anser cygnoides and Anser anser embryos (E12, E13 E18, and E28) and after birth gosling stages (G18, G48, G88) for gene expression analysis.

RESULTS

CTNNB1 and LEF1 genes were expressed in Anser cygnoides and Anser anser at different embryonic and after-birth gosling developmental stages and the expression levels were significantly different in different stages (p < 0.05). The mRNA expression of CTNNB1 and LEF1 genes reached the highest level at D88 in Anser cygnoides, while the highest expression levels were at D18 and D88 in Anser anser, and the expression levels of CTNNB1 genes at D88 in all embryonic stages were significantly lower than after-birth stages. CTNNB1 and LEF1 protein expression were the highest at E12 and E28 for Anser cygnoides feather follicles development. While at a similar stage for Anser anser, the expression of CTNNB1 and LEF1 protein was the highest at D48 and D18. Protein expression at embryonic stages was in the epidermis (E) and the hair basal plate (P), the expression site for after-birth stages was in the dermal papilla (DP).

CONCLUSION

Our study illustrated that CTNNB1 and LEF1 has an impact on Anser cygnoides and Anser anser feather follicles growth and development.

Strawberry Notch 1 (SBNO1) promotes proliferation of spermatogonial stem cells via the noncanonical Wnt pathway in mice

While it is known that spermatogonial stem cells (SSCs) initiate the production of male germ cells, the mechanisms of SSC self-renewal, proliferation, and differentiation remain poorly understood. We have previously identified Strawberry Notch 1 (SBNO1), a vertebrate strawberry notch family protein, in the proteome profile for mouse SSC maturation and differentiation, revealing SBNO1 is associated with neonatal testicular development. To explore further the location and function of SBNO1 in the testes, we performed Sbno1 gene knockdown in mice to study the effects of SBNO1 on neonatal testicular and SSC development. Our results revealed that SBNO1 is required for neonatal testicular and SSC development in mice. Particularly, in vitro Sbno1 gene knockdown with morpholino oligonucleotides caused a reduction of SSCs and inactivation of the noncanonical Wnt pathway, through Jun N-terminal kinases. Our study suggests SBNO1 maintains SSCs by promoting the noncanonical Wnt pathway.

Characterization of Embryonic Skin Transcriptome in Anser cygnoides at Three Feather Follicles Developmental Stages

In order to enrich the Anser cygnoides genome and identify the gene expression profiles of primary and secondary feather follicles development, de novo transcriptome assembly of skin tissues was established by analyzing three developmental stages at embryonic day 14, 18, and 28 (E14, E18, E28). Sequencing output generated 436,730,608 clean reads from nine libraries and de novo assembled into 56,301 unigenes. There were 2,298, 9,423 and 12,559 unigenes showing differential expression in three stages respectively. Furthermore, differentially expressed genes (DEGs) were functionally classified according to genes ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and series-cluster analysis. Relevant specific GO terms such as epithelium development, regulation of keratinocyte proliferation, morphogenesis of an epithelium were identified. In all, 15,144 DEGs were clustered into eight profiles with distinct expression patterns and 2,424 DEGs were assigned to 198 KEGG pathways. Skin development related pathways (mitogen-activated protein kinase signaling pathway, extra-cellular matrix -receptor interaction, Wingless-type signaling pathway) and genes (delta like canonical Notch ligand 1, fibroblast growth factor 2, Snail family transcriptional repressor 2, bone morphogenetic protein 6, polo like kinase 1) were identified, and eight DEGs were selected to verify the reliability of transcriptome results by real-time quantitative PCR. The findings of this study will provide the key insights into the complicated molecular mechanism and breeding techniques underlying the developmental characteristics of skin and feather follicles in Anser cygnoides.

Thyroid hormone (T3) is involved in inhibiting the proliferation of newborn calf Sertoli cells via the PI3K/Akt signaling pathway in vitro

The experiment was designed to study the effects of Thyroid hormone (T₃) on the proliferation and differentiation of newborn calf Sertoli cells (SCs) to provide a theoretical and practical basis for increased testicular semen production. In this experiment, the cck8 method was used to detect the effects of different concentrations of T₃ on the proliferation rate of newborn calf SCs. qPCR and Western Blot methods were used to explore the effects of T3 on the proliferation and differentiation of calves SCs and whether T₃ through Wnt/β-catenin and PI3K/Akt pathways can regulate the proliferation and differentiation of SCs. We found that dosage (T₃) and time correlated with proliferation inhibition of SC. T₃ inhibited the proliferation of SC by down-regulating cyclinD1, upregulating p21Cip, p27Kip1, and other cell-cycle factors. By up-regulating AR and down-regulating KRT-18, T3 promoted the maturated differentiation of SC. T₃ could not affect the expression of β-catenin in SC of newborn calf, indicating that T₃ may not regulate SCs proliferation through the Wnt pathway. T3 also negatively regulated the gene expression and protein levels of some genes in the PI3K/Akt signaling pathway. We concluded that T₃ inhibited newborn calf SCs proliferation through the PI3K/Akt signaling pathway and possibly promoted their differentiation.

MicroRNA-322 Regulates Self-renewal of Mouse Spermatogonial Stem Cells through Rassf8

Spermatogonial stem cells (SSCs) are essential for spermatogenesis and male fertility. MicroRNAs (miRs) are key regulators of gene expression involved in self-renewal, differentiation, and apoptosis. However, the function and mechanisms of individual miR in regulating self-renewal and differentiation of SSCs remain unclear. Here, we report for the first time that miR-322 regulates self-renewal of SSCs. Functional assays revealed that miR-322 was essential for SSC self-renewal. Mechanistically, miR-322 promoted SSC self-renewal by targeting RASSF8 (ras association domain family 8). Moreover, the WNT/β-catenin signaling pathway was involved in the miR-322-mediated regulation. Furthermore, miR-322 overexpression increased GFRα1, ETV5 and PLZF expression but decreased STRA8, C-KIT and BCL6 expression. Our study provides not only a novel insight into molecular mechanisms regulating SSC self-renewal but also a basis for the diagnosis, treatment, and prevention of male infertility.

Integrative Proteomic and Phosphoproteomic Profiling of Testis from Wip1 Phosphatase-Knockout Mice: Insights into Mechanisms of Reduced Fertility

Mice lacking wild-type p53-induced phosphatase 1 (Wip1) display male reproductive defects including smaller testes, subfertility and spermatogenesis defects at the round- and elongating-spermatid stages. However, the molecular mechanisms underlying these abnormalities remain unclear. Here we examined the proteome and phosphoproteome of testes from Wip1-knockout mice using a quantitative proteomic approach. From a total of 6872 proteins and 4280 phosphorylation sites identified, 58 proteins and 159 phosphorylation sites were found to be differentially regulated compared with wild type mice. Pathway enrichment analyses revealed that these regulated proteins and phosphosites were mainly involved in adherens/tight junctions, apoptosis, inflammatory response, spermatogenesis, sperm motility, and cytoskeletal assembly and depolymerization. Wip1-knockout mice showed decreased expression of junction-associated proteins (occludin, ZO-1, and N-cadherin) and impaired integrity of the blood-testis barrier. In addition, Wip1 deficiency was associated with elevated levels of cytokines and germ cell apoptosis in the testis. These results suggest that proinflammatory cytokines may impair the blood-testis barrier dynamics by decreasing the expression of junction-associated proteins, which could lead to subfertility and spermatogenesis defects. Collectively, these findings help to explain the low reproductive function caused by Wip1 deletion and provide novel insights into our understanding of causes of male infertility.

Wnt/β-catenin signaling enhances transcription of the CX43 gene in murine Sertoli cells

Sertoli cells provide the nutritional and metabolic support for germ cells. Wnt/β-catenin signaling is important for the development of the seminiferous epithelium during embryonic age, although after birth this pathway is downregulated. Cx43 gene codes for a protein that is critical during testicular development. The Cx43 promoter contains TCF/β-catenin binding elements (TBEs) that contribute CX43 expression in different cell types and which may also be regulating the expression of this gene in Sertoli cells. In this study, we demonstrate that 42GPA9 Sertoli cells respond to treatments that result in accumulation of β-catenin within the nucleus and in upregulation of CX43 gene transcription. β-Catenin binds to TBEs located both upstream and downstream of the transcriptional start site (TSS). Luciferase reporter experiments revealed that TBEs located upstream of the TSS are necessary for β-catenin-mediated upregulation. Our results also indicate that the Wnt/β-catenin-dependent upregulation of the Cx43 gene in Sertoli cells is accompanied by changes in epigenetic parameters that may be directly contributing to generating a chromatin environment that facilitates the establishment of the transcriptional machinery at this promoter.

The influence of retinoic acid-induced differentiation on the radiation response of male germline stem cells

Lifelong mammalian male fertility is maintained through an intricate balance between spermatogonial proliferation and differentiation. DNA damage in spermatogonia, for instance caused by chemo- or radiotherapy, can induce cell cycle arrest or germ cell apoptosis, possibly resulting in male infertility. Spermatogonia are generally more radiosensitive and prone to undergo apoptosis than somatic cells. Among spermatogonial subtypes the response to DNA damage is differentially modulated; undifferentiated spermatogonia, including the spermatogonial stem cells (SSCs), are relatively radio-resistant, whereas differentiating spermatogonia are very radiosensitive. To investigate the molecular mechanisms underlying this difference, we used an in vitro system consisting of mouse male germline stem (GS) cells that can be induced to differentiate. Using RNA-sequencing analysis, we analyzed the response of undifferentiated and differentiating GS cells to ionizing radiation (IR). At the RNA expression level, both undifferentiated and differentiating GS cells showed a very similar response to IR. Protein localization of several genes found to be involved in either spermatogonial differentiation or radiation response was investigated using mouse testis sections. For instance, we found that the transcription factor PDX1 was specifically expressed in undifferentiated spermatogonia and thus may be a novel marker for these cells. Interestingly, also at the protein level, undifferentiated GS cells showed a more pronounced upregulation of p53 in response to IR than differentiating GS cells. The higher p53 protein level in undifferentiated spermatogonia may preferentially induce cell cycle arrest, thereby giving these cells more time to repair inflicted DNA damage and increase their radio-resistance.

Stromal interaction molecule 1 is required for neonatal testicular development in mice

Stromal interaction molecule 1 (STIM1) is a transmembrane endoplasmic reticulum protein, and it serves as a Ca²⁺ sensor and activator of store-operated Ca²⁺ entry (SOCE). We have previously identified STIM1 in the proteome profile of mice neonatal testes, revealing STIM1 to be associated with neonatal testicular development. Here, to further explore the location and function of STIM1 in mice testes, we studied the effect of Stim1 gene knockdown on neonatal testicular development by testicular culture. Our results revealed that STIM1 was primarily located in Sertoli cells. Knockdown of Stim1 gene using morpholino in neonatal testis caused the mislocation of Sertoli cells and loss of germ cells, which were associated with the aberrant reactive oxygen species (ROS) activation, while inhibition of ROS could partly rescue the phenotypes caused by Stim1 gene knockdown. In conclusion, our study suggests that STIM1 can maintain neonatal testicular development by inhibiting ROS activation.

Roles of microRNAs in mammalian reproduction: from the commitment of germ cells to peri-implantation embryos

MicroRNAs (miRNAs) are active regulators of numerous biological and physiological processes including most of the events of mammalian reproduction. Understanding the biological functions of miRNAs in the context of mammalian reproduction will allow a better and comparative understanding of fertility and sterility in male and female mammals. Herein, we summarize recent progress in miRNA‐mediated regulation of mammalian reproduction and highlight the significance of miRNAs in different aspects of mammalian reproduction including the biogenesis of germ cells, the functionality of reproductive organs, and the development of early embryos. Furthermore, we focus on the gene expression regulatory feedback loops involving hormones and miRNA expression to increase our understanding of germ cell commitment and the functioning of reproductive organs. Finally, we discuss the influence of miRNAs on male and female reproductive failure, and provide perspectives for future studies on this topic.

Noncoding RNAs: Potential players in the self-renewal of mammalian spermatogonial stem cells

Spermatogonial stem cells (SSCs), a unique population of male germ cells with self-renewal ability, are the foundation for maintenance of spermatogenesis throughout the life of the male. Although many regulatory molecules essential for SSC self-renewal have been identified, the fundamental mechanism underlying how SSCs acquire and maintain their self-renewal activity remains largely to be elucidated. In recent years, many types of noncoding RNAs (ncRNAs) have been suggested to regulate the SSC self-renewal through multiple ways, indicating ncRNAs play crucial roles in SSC self-renewal. In this paper, we mainly focus on four types of ncRNAs including microRNA, long ncRNA, piwi-interacting RNA, as well as circular RNAs, and reviewed their potential roles in SSC self-renewal that discovered recently to help us gain a better understanding of molecular mechanisms by which ncRNAs perform their function in regulating SSC self-renewal.

Wnt3a Ectopic Expression Interferes Axonal Projection and Motor Neuron Positioning During the Chicken Spinal Cord Development

The formation of dorsal-ventral axis of the spinal cord is controlled largely by dorsal signals such as Wnts (which are members of the wingless + MMTV integrants, Int family), besides ventral signals such as sonic hedgehog (Shh). Wnt3a, one of the Wnt family members, is involved in multiple cellular functions, including self-renewal, proliferation, differentiation, and motility. Here, we aim to study the mechanism of the regulation of chicken spinal cord patterning by Wnt3a. In this study, Wnt3a was ectopically expressed in the spinal cord of developing chicken embryos by in ovo electroporation. The results of immunofluorescent staining revealed that Wnt3a ectopic expression caused the abnormality of commissural axonal projection and the formation of nerve fibers was interrupted. It is worth noting that neurons in the ventricular zone, especially motor neurons, could not migrate laterally after the Wnt3a overexpression, which led to the malformation of motor column. In addition, we found that neurons could not protrude axons outwardly after overexpression of Wnt3a in the spinal cord. It was also found that Wnt3a overexpression inhibited the outgrowth of processes in culturing SH-SY5Y cells. In conclusion, we proposed that Wnt3a regulates neuronal morphology, which subsequently disrupts axonal projection and motor neuron positioning during spinal cord development.

Systems genomics study reveals expression quantitative trait loci, regulator genes and pathways associated with boar taint in pigs

Boar taint is an offensive odour and/or taste from a proportion of non-castrated male pigs caused by skatole and androstenone accumulation during sexual maturity. Castration is widely used to avoid boar taint but is currently under debate because of animal welfare concerns. This study aimed to identify expression quantitative trait loci (eQTLs) with potential effects on boar taint compounds to improve breeding possibilities for reduced boar taint. Danish Landrace male boars with low, medium and high genetic merit for skatole and human nose score (HNS) were slaughtered at ~100 kg. Gene expression profiles were obtained by RNA-Seq, and genotype data were obtained by an Illumina 60K Porcine SNP chip. Following quality control and filtering, 10,545 and 12,731 genes from liver and testis were included in the eQTL analysis, together with 20,827 SNP variants. A total of 205 and 109 single-tissue eQTLs associated with 102 and 58 unique genes were identified in liver and testis, respectively. By employing a multivariate Bayesian hierarchical model, 26 eQTLs were identified as significant multi-tissue eQTLs. The highest densities of eQTLs were found on pig chromosomes SSC12, SSC1, SSC13, SSC9 and SSC14. Functional characterisation of eQTLs revealed functions within regulation of androgen and the intracellular steroid hormone receptor signalling pathway and of xenobiotic metabolism by cytochrome P450 system and cellular response to oestradiol. A QTL enrichment test revealed 89 QTL traits curated by the Animal Genome PigQTL database to be significantly overlapped by the genomic coordinates of cis-acting eQTLs. Finally, a subset of 35 cis-acting eQTLs overlapped with known boar taint QTL traits. These eQTLs could be useful in the development of a DNA test for boar taint but careful monitoring of other overlapping QTL traits should be performed to avoid any negative consequences of selection.

miR‐31 Regulates Spermatogonial Stem Cells Meiosis via Targeting Stra8

Stra8 (stimulated by retinoic acid gene 8) is a specific gene that is expressed in mammalian germ cells during transition from mitosis to meiosis and plays a key role in the initiation of meiosis in mammals and birds. So, the evaluation of the Stra8 pathway in cSSCs may provide a deeper insight into mammalian spermatogenesis. miRNA was also an important regulating factor for meiosis of SSCs. However, there is currently no data indicating that miRNA regulate the meiosis of SSCs via Stra8. Here, we predicted the prospective miRNA targeting to Stra8 using the online Bioinformatics database‐Targetscan, and performed an analysis of the dual‐luciferase recombinant vector, pGL3‐CMV‐LUC‐MCS‐Stra8‐3′UTR. miR‐31 mimics (miR‐31m), miR‐31 inhibitors (miR‐31i), Control (NC, scrambled oligonucleotides transfection) were transfected into cSSCs; Stra8 and miRNA were analyzed by RT‐qPCR, immunofluorescence, and Western blot. The detection of haploid was conducted by flow cytometry. The results showed that miR‐31 regulates meiosis of cSSCs via targeting Stra8 in vitro and in vivo. Our study identifies a new regulatory pathway that miR‐31 targets Stra8 and inhibits spermatogenesis. J. Cell. Biochem. 118: 4844–4853, 2017. © 2017 Wiley Periodicals, Inc.

Long Non Coding RNA Expression Intersecting Cancer and Spermatogenesis: A Systematic Review

Background: Numerous similarities have been noted between gametogenic and tumorigenic programs in features such as global hypomethylation, immune evasion, immortalization, meiosis induction, and migration. In addition, aberrant expression of testis specific genes has been detected in various cancers which has led to categorization of these genes as “cancer-testis genes”. Most of the examples identified in this category are protein encoding. However, recent studies have revealed that non-coding RNAs, including long non coding RNAs (lncRNAs), may have essential regulatory roles in telomere biology, chromatin dynamics, modulation of gene expression and genome structural organization. All of these functions are implicated in both gametogenic and tumorigenic programs. Methods: In the present study, we conducted a computerized search of the MEDLINE/PUBMED and Embase databases with the key words lncRNA, gametogenesis, testis and cancer. Results: We found a number of lncRNAs with essential roles and notable expression in both gametogenic and cancer tissues. Conclusions: Comparison between cancer tissues and gametogenic tissues has shown that numerous lncRNAs are expressed in both, playing similar roles in processes modulated by signaling pathways such as Wnt/β-catenin and PI3K/AKT/mTOR. Evaluation of expression patterns and functions of these genes should pave the way to discovery of biomarkers for early detection, prognostic assessment and evaluation of therapeutic responses in cancers.

From the Cover: An Animal-Free In Vitro Three-Dimensional Testicular Cell Coculture Model for Evaluating Male Reproductive Toxicants

Primary testicular cell coculture model has been used to evaluate testicular abnormalities during development, and was able to identify the testicular toxicity of phthalates. However, the primary testicular cell coculture model has disadvantages in employing animals for the isolation of testicular cells, and the complicated isolation procedure leads to inconsistent results. We developed an invitro testicular coculture model from rodent testicular cell lines, including spermatogonial cells, Sertoli cells, and Leydig cells with specified cell density and extracellular matrix (ECM) composition. Using comparative high-content analysis of F-actin cytoskeletal structure between the coculture and single cell culture models, we demonstrated a 3D structure of the coculture, which created an invivo-like niche, and maintained and supported germ cells within a 3D environment. We validated this model by discriminating between reproductive toxicants and nontoxicants among 32 compounds in comparison to the single cell culture models. Furthermore, we conducted a comparison between the invitro (IC50) and invivo reproductive toxicity testing (lowest observed adverse effect level on reproductive system). We found the invitro coculture model could classify the tested compounds into 4 clusters, and identify the most toxic reproductive substances, with high concordance, sensitivity, and specificity of 84%, 86.21%, and 100%, respectively. We observed a strong correlation of IC50 between the invitro coculture model and the invivo testing results. Our results suggest that this novel invitro coculture model may be useful for screening testicular toxicants and prioritize chemicals for further assessment in the future.

Wnt signaling pathway regulates differentiation of chicken embryonic stem cells into spermatogonial stem cells via Wnt5a

In this study, we investigated the mechanism of signaling pathway-mediated differentiation of embryonic stem cells (ESCs) into spermatogonial stem cells (SSCs) in chicken. The Wnt signaling pathway was identified based on previous RNA Sequencing results and was proven a crucial signaling pathway that participates in the differentiation of ESCs into SSCs. In retinoic acid (RA) induction experiments in vitro, we found that Wnt signaling expression was inhibited by Wnt5a-shRNA, resulting in decreased expression of corresponding marker genes in SSCs, C-kit, Cvh, integrin α6 and integrin β1, but it was significantly promoted by RA treatment. Immunofluorescence assay showed that percentage of C-kit, Cvh, and integrin α6 and integrin β1-positive cells in RA treatment group and Wnt5a overexpression group was significantly higher than that in Wnt5a signaling interference group. Results of fluorescence-activated cell sorting analysis (FACS) also showed that proportion of germ-like cells was reduced by 14.3% (from 18.3% to 4.0%) at day 4 and 15.4% (from 18.6% to 3.2%) at day 12 after transfection, respectively. In experiments in vivo, shRNA-Wnt5a was stably expressed in fertilized chicken embryos and significantly reduced germ cell formation by 11.3% (from 21.7% to 10.4%) and 3.7% (6.4% from 10.1%). Results of quantitative PCR (qRT-PCR) and western blot assays showed that the expression of some specific germ cell marker genes, integrin α6 and integrin β1, was significantly suppressed following Wnt5a signaling interference in vivo. Taken together, our study suggests that Wnt signaling pathway could regulate positively the differentiation of chicken ESCs into SSCs through Wnt5a.

Genome-wide analysis of long non-coding RNAs and their role in postnatal porcine testis development

A comprehensive and systematic understanding of the roles of lncRNAs in the postnatal development of the pig testis has still not been achieved. In the present study, we obtained more than one billion clean reads and identified 15,528 lncRNA transcripts; these transcripts included 5032 known and 10,496 novel porcine lncRNA transcripts and corresponded to 10,041 lncRNA genes. Pairwise comparisons identified 449 known and 324 novel lncRNAs that showed differential expression patterns. GO and KEGG pathway enrichment analyses revealed that the targeted genes were involved in metabolic pathways regulating testis development and spermatogenesis, such as the TGF-beta pathway, the PI3K-Akt pathway, the Wnt/β-catenin pathway, and the AMPK pathway. Using this information, we predicted some lncRNAs and coding gene pairs were predicted that may function in testis development and spermatogenesis; these are listed in detail. This study has provided the most comprehensive catalog to date of lncRNAs in the postnatal pig testis and will aid our understanding of their functional roles in testis development and spermatogenesis.