Nonobstructive azoospermia (NOA) is a severe and heterogeneous form of male factor infertility caused by dysfunction of spermatogenesis. Although various factors are well defined in the disruption of spermatogenesis, not all aspects due to the heterogeneity of the disorder have been determined yet. In this review, we focus on the recent findings and summarize the current data on epigenetic mechanisms such as DNA methylation and different metabolites produced during methylation and demethylation and various types of small noncoding RNAs involved in the pathogenesis of different groups of NOA.
Humans ; Azoospermia/metabolism* ; Male ; DNA Methylation/genetics* ; Epigenesis, Genetic ; Spermatogenesis/genetics* ; RNA, Small Untranslated/genetics*

OBJECTIVE: To explore the role of nuclear receptor-binding SET-domain protein 1 (NSD1) in the pathogenesis of nonobstructive azoospermia (NOA) by regulating the expressions of relevant genes. METHODS: We detected the expression of NSD1 in the testis tissue of 7 male patients with obstructive azoospermia (OA) and 18 with NOA by qPCR and immunofluorescence assay, and determined the modification level of H3K36me2 in the testes of two groups of patients by immunofluorescence staining, Western blot and immunoprecipitation (IP). We examined the difference in the enrichment of H3K36me2 in the testis tissue by chromatin IP-based sequencing (ChIP-Seq), analyzed the genomic distribution and target genes using bioinformatics, and verified the expression levels of the target genes in the testes of the two groups of patients by qPCR. RESULTS: Compared with the patients with OA, those with NOA showed dramatically decreased mRNA and protein expressions of NSD1 (P=0.000 8). The binding of NSD1 to H3K36me2 was observed in the testis tissue of both the two groups of patients, while the modification level of H3K36me2 was evidently reduced in the NOA males. H3K36me2 was distributed mainly in the intergenic region in the testes of the two groups of patients, but the enrichment of H3K36me2 was obviously decreased in the NOA group. The differentially H3K36me2-enriched genes were involved in various biological processes, including tissue development, and cell morphogenesis. Results of ChIP-Seq and qPCR showed significantly down-regulated expressions of the target genes KIT, SPO11 and ACRV1 in the testis tissue of the NOA males compared with those in the OA patients (P<0.01). CONCLUSION The levels of NSD1 and H3K36me2 are decreased in testis tissue of the NOA patient, H3K36me2 is highly enriched in the spermatogenesis-related key genes KIT, SPO11 and ACRV1, and the down-regulated expression of NSD1 impairs spermatogenesis.
Humans ; Male ; Azoospermia/genetics* ; Testis/metabolism* ; Histone-Lysine N-Methyltransferase/metabolism* ; Histones/metabolism*

Thanks to tremendous advances in sequencing technologies and in particular to whole exome sequencing (WES), many genes have now been linked to severe sperm defects. A precise genetic diagnosis is obtained for a minority of patients and only for the most severe defects like azoospermia or macrozoospermia which is very often due to defects in the aurora kinase C (AURKC gene. Here, we studied a subject with a severe oligozoospermia and a phenotypic diagnosis of macrozoospermia. AURKC analysis did not reveal any deleterious variant. WES was then initiated which permitted to identify a homozygous loss of function variant in the zinc finger MYND-type containing 15 (ZMYND15 gene. ZMYND15 has been described to serve as a switch for haploid gene expression, and mice devoid of ZMYND15 were shown to be sterile due to nonobstructive azoospermia (NOA). In man, ZMYND15 has been associated with NOA and severe oligozoospermia. We confirm here that the presence of a bi-allelic ZMYND15 variant induces a severe oligozoospermia. In addition, we show that severe oligozoospermia can be associated macrozoospermia, and that a phenotypic misdiagnosis is possible, potentially delaying the genetic diagnosis. In conclusion, genetic defects in ZMYND15 can induce complete NOA or severe oligozoospermia associated with a very severe teratozoospermia. In our experience, severe oligozoospermia is often associated with severe teratozoospermia and can sometimes be misinterpreted as macrozoospermia or globozoospermia. In these instances, specific AURKC or dpy-19 like 2 (DPY19L2) diagnosis is usually negative and we recommend the direct use of a pan-genomic techniques such as WES.
Animals ; Azoospermia/genetics* ; Humans ; Infertility, Male/genetics* ; Male ; Membrane Proteins/genetics* ; Mice ; Mutation ; Oligospermia/genetics* ; Repressor Proteins/metabolism* ; Teratozoospermia/genetics*

Circular RNAs (circRNAs) are highly conserved and ubiquitously expressed noncoding RNAs that participate in multiple reproduction-related diseases. However, the expression pattern and potential functions of circRNAs in the testes of patients with non-obstructive azoospermia (NOA) remain elusive. In this study, according to a circRNA array, a total of 37 881 circRNAs were identified that were differentially expressed in the testes of NOA patients compared with normal controls, including 19 874 upregulated circRNAs and 18 007 downregulated circRNAs. Using quantitative real-time polymerase chain reaction (qRT-PCR) analysis, we confirmed that the change tendency of some specific circRNAs, including hsa_circ_0137890, hsa_circ_0136298, and hsa_circ_0007273, was consistent with the microarray data in another larger sample. The structures and characteristics of these circRNAs were confirmed by Sanger sequencing, and fluorescence in situ hybridization revealed that these circRNAs were primarily expressed in the cytoplasm. Bioinformatics analysis was used to construct the competing endogenous RNA (ceRNA) network, and numerous miRNAs that could be paired with circRNAs validated in this study were reported to be vital for spermatogenesis regulation. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses indicated that genes involved in axoneme assembly, microtubule-based processes, and cell proliferation were significantly enriched. Our data suggest that there are aberrantly expressed circRNA profiles in patients with NOA and that these circRNAs may help identify key diagnostic and therapeutic molecular biomarkers for NOA patients.
Male ; Humans ; RNA, Circular/genetics* ; Azoospermia/genetics* ; In Situ Hybridization, Fluorescence ; MicroRNAs/metabolism*

Azoospermia patients who carry a monogenetic mutation that causes meiotic arrest may have their biological child through genetic correction in spermatogonial stem cells (SSCs). However, such therapy for infertility has not been experimentally investigated yet. In this study, a mouse model with an X-linked testis-expressed 11 (TEX11) mutation (Tex11
Adult Germline Stem Cells/metabolism* ; Animals ; Azoospermia/genetics* ; Infertility, Male/therapy* ; Male ; Mice ; Mutation/genetics* ; Spermatogenesis/genetics*

Many studies have shown that microRNAs (miRNAs) play vital roles during the spermatogenesis. However, little is known about the altered miRNA profiles of testicular tissues in nonobstructive azoospermia (NOA). Using microarray technology, the miRNA expression profiles of testicular biopsies from patients with NOA and of normal testicular tissues were determined. Bioinformatics analyses were conducted to predict the enriched biological processes and functions of identified miRNAs. The microarray data were validated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the results of which were then validated with a larger sample size. Correlations between the miRNA expression levels and clinical characteristics were analyzed. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic ability of miRNAs for azoospermia. Hierarchical clustering showed that 129 miRNAs were significantly differentially expressed between the NOA and control groups. Bioinformatics analysis indicated that the differentially expressed miRNAs were involved in spermatogenesis, cell cycle, and mitotic prometaphase. In the subsequent qRT-PCR assays, the selected miRNA expression levels were consistent with the microarray results, and similar validated results were obtained with a larger sample size. Some clinical characteristics were significantly associated with the expression of certain miRNAs. In particular, we identified a combination of two miRNAs (miR-10b-3p and miR-34b-5p) that could serve as a predictive biomarker of azoospermia. This study provides altered miRNA profiles of testicular biopsies from NOA patients and examines the roles of miRNAs in spermatogenesis. These profiles may be useful for predicting and diagnosing the presence of testicular sperm in individuals with azoospermia.
Adult ; Azoospermia/genetics* ; Biopsy ; Cluster Analysis ; Computational Biology ; Follicle Stimulating Hormone/metabolism* ; Gene Expression Profiling ; Humans ; Luteinizing Hormone/metabolism* ; Male ; MicroRNAs/metabolism* ; Reverse Transcriptase Polymerase Chain Reaction ; Spermatogenesis/genetics* ; Testis/metabolism* ; Testosterone/metabolism* ; Tissue Array Analysis

ObjectiveTo study the expression of CLAUDIN-11 in the testis tissue of non-obstructive azoospermia (NOA) patients with different severities and investigate its clinical significance.

METHODSSixty-two NOA patients were divided into a hypospermatogenesis (HS) group (n = 30) and a Sertoli cell only syndrome (SCO) group (n =32). The expression of CLAUDIN-11 in the testicular tissue of the patients was detected by immunohistochemistry, that of CLAUDIN-11 mRNA determined by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR), and the levels of serum reproductive hormones measured by chemiluminescent immunoassay.

RESULTSImmunohistochemistry showed that the expression of CLAUDIN-11 was mainly in the cytoplasm of the Sertoli cells around the seminiferous tubule wall in the HS group, but diffusely distributed in the membrane of the Sertoli cells in the SCO group. RT-qPCR revealed a significantly lower expression of CLAUDIN-11 mRNA in the HS than in the SCO group (0.008 ± 0.001 vs 0.013 ± 0.002, t = 10.616, P<0.01). The level of serum luteotropic hormone (LH) was also markedly lower in the HS than in the SCO group (［3.62 ± 1.34］ vs ［4.96 ± 3.10］ IU/L, P<0.05) and so was that of follicle-stimulating hormone (FSH) (［5.36 ± 2.80］ vs ［10.65 ± 9.18］ IU/L, P<0.05).

CONCLUSIONSThe up-regulated expression of CLAUDIN-11 in Sertoli cells may play an important role in the development and progression of spermatogenic dysfunction in NOA patients.

Azoospermia ; genetics ; metabolism ; Claudins ; metabolism ; Follicle Stimulating Hormone ; metabolism ; Humans ; Male ; Oligospermia ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Seminiferous Tubules ; metabolism ; Sertoli Cell-Only Syndrome ; genetics ; metabolism ; Sertoli Cells ; metabolism ; Spermatogenesis ; Testis ; metabolism

Adult ; Azoospermia/genetics* ; Follicle Stimulating Hormone/metabolism* ; Gonadal Dysgenesis, Mixed/pathology* ; Growth Disorders/genetics* ; Humans ; In Situ Hybridization, Fluorescence ; Infertility, Male/genetics* ; Karyotype ; Luteinizing Hormone/metabolism* ; Male ; Mosaicism ; Testis/pathology* ; Testosterone/metabolism* ; Turner Syndrome

In about half the cases of involuntary childlessness, a male infertility factor is involved. The PIWI-LIKE genes, a subclade of the Argonaute protein family, are involved in RNA silencing and transposon control in the germline. Knockout of murine Piwi-like 1 and 2 homologs results in complete infertility in males. The aim of this study was to analyze whether the mRNA expression of human PIWI-LIKE 1-4 genes is altered in ejaculated spermatozoa of men with impaired sperm characteristics. Ninety male participants were included in the study, among which 47 were with normozoospermia, 36 with impaired semen characteristics according to the World Health Organization (WHO) manual, 5^th edition, and 7 with azoospermia serving as negative control for the PIWI-LIKE 1-4 mRNA expression in somatic cells in the ejaculate. PIWI-LIKE 1-4 mRNA expression in the ejaculated spermatozoa of the participants was measured by quantitative real-time PCR. In nonazoospermic men, PIWI-LIKE 1-4 mRNA was measurable in ejaculated spermatozoa in different proportions. PIWI-LIKE 1 (100.0%) and PIWI-LIKE 2 (49.4%) were more frequently expressed than PIWI-LIKE 3 (9.6%) and PIWI-LIKE 4 (15.7%). Furthermore, a decreased PIWI-LIKE 2 mRNA expression showed a significant correlation with a decreased sperm count (P = 0.022) and an increased PIWI-LIKE 1 mRNA expression with a decreased progressive motility (P = 0.048). PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression exhibited a significant association with impaired sperm characteristics and may be a useful candidate for the evaluation of the impact of PIWI-LIKE 1-4 mRNA expression on male infertility.
Adult ; Argonaute Proteins/genetics* ; Azoospermia/genetics* ; Case-Control Studies ; Gene Expression ; Humans ; Infertility, Male/genetics* ; Male ; Middle Aged ; RNA, Messenger/metabolism* ; RNA-Binding Proteins ; Sperm Count ; Sperm Motility/genetics* ; Spermatozoa/metabolism* ; Young Adult

This study was performed to investigate a potential marker for the presence of spermatozoa in the ejaculate following varicocelectomy in Chinese men with nonobstructive azoospermia and varicoceles. The micro-RNA (miR)-192a levels in seminal plasma and testicular tissue were evaluated by quantitative real-time polymerase chain reaction from 60 men with nonobstructive azoospermia and varicoceles (Group A: 27 men with spermatozoa found in the ejaculate after surgery; Group B: 33 men without spermatozoa found in the ejaculate after surgery) and 30 controls. The seminal plasma and testicular tissue miR-192a levels were higher in Group B than in Group A and the controls (P < 0.001), and there was no significant difference between Group A and the controls (P > 0.05). Apoptosis and proliferation assays with miR mimics and inhibitors showed that miR-192a induced GC-2 cell apoptosis through the activation of Caspase-3 protein. Thus, seminal plasma miR-192a appears to be a potential marker for successfully indicating spermatozoa in the ejaculate following microsurgical varicocelectomy in men with nonobstructive azoospermia and varicoceles. Seminal plasma miR-192a may be a useful clinical marker for prescreening to determine which patients with nonobstructive azoospermia and varicoceles would benefit from varicocelectomy.
Adult ; Apoptosis ; Asian People ; Azoospermia/surgery* ; Biomarkers/analysis* ; Caspase 3/analysis* ; Cell Proliferation ; Humans ; Infertility, Male/etiology* ; Male ; MicroRNAs/biosynthesis* ; Microsurgery ; Predictive Value of Tests ; Semen/metabolism* ; Testis/metabolism* ; Treatment Outcome ; Varicocele/surgery*