Novel axonemal protein ZMYND12 interacts with TTC29 and DNAH1, and is required for male fertility and flagellum function

Male infertility is common and complex, presenting a wide range of heterogeneous phenotypes. Although about 50% of cases are estimated to have a genetic component, the underlying cause often remains undetermined. Here, from whole-exome sequencing on samples from 168 infertile men with asthenoteratozoospermia due to severe sperm flagellum, we identified homozygous ZMYND12 variants in four unrelated patients. In sperm cells from these individuals, immunofluorescence revealed altered localization of DNAH1, DNALI1, WDR66, and TTC29. Axonemal localization of ZMYND12 ortholog TbTAX-1 was confirmed using the Trypanosoma brucei model. RNAi knock-down of TbTAX-1 dramatically affected flagellar motility, with a phenotype similar to the sperm from men bearing homozygous ZMYND12 variants. Co-immunoprecipitation and ultrastructure expansion microscopy in T. brucei revealed TbTAX-1 to form a complex with TTC29. Comparative proteomics with samples from Trypanosoma and Ttc29 KO mice identified a third member of this complex: DNAH1. The data presented revealed that ZMYND12 is part of the same axonemal complex as TTC29 and DNAH1, which is critical for flagellum function and assembly in humans, and Trypanosoma. ZMYND12 is thus a new asthenoteratozoospermia-associated gene, bi-allelic variants of which cause severe flagellum malformations and primary male infertility.

Advances in the study of genetic factors and clinical interventions for fertilization failure

Fertilization failure refers to the failure in the pronucleus formation, evaluating 16-18 h post in vitro fertilization or intracytoplasmic sperm injection. It can be caused by sperm, oocytes, and sperm-oocyte interaction and lead to great financial and physical stress to the patients. Recent advancements in genetics, molecular biology, and clinical-assisted reproductive technology have greatly enhanced research into the causes and treatment of fertilization failure. Here, we review the causes that have been reported to lead to fertilization failure in fertilization processes, including the sperm acrosome reaction, penetration of the cumulus and zona pellucida, recognition and fusion of the sperm and oocyte membranes, oocyte activation, and pronucleus formation. Additionally, we summarize the progress of corresponding treatment methods of fertilization failure. This review will provide the latest research advances in the genetic aspects of fertilization failure and will benefit both researchers and clinical practitioners in reproduction and genetics.

Human globozoospermia-related genes and their role in acrosome biogenesis

The mammalian acrosome is a secretory vesicle attached to the sperm nucleus whose fusion with the overlying plasma membrane is required to achieve fertilization. Acrosome biogenesis starts during meiosis, but it lasts through the entire process of haploid cell differentiation (spermiogenesis). Acrosome biogenesis is a stepwise process that involves membrane traffic from the Golgi apparatus, but it also seems that the lysosome/endosome system participates in this process. Defective sperm head morphology is accompanied by defective acrosome shape and function, and patients with these characteristics are infertile or subfertile. The most extreme case of acrosome biogenesis failure is globozoospermia syndrome, which is primarily characterized by the presence of round-headed spermatozoa without acrosomes with cytoskeleton defects around the nucleus and infertility. Several genes participating in acrosome biogenesis have been uncovered using genetic deletions in mice, but only a few of them have been found to be deleted or modified in patients with globozoospermia. Understanding acrosome biogenesis is crucial to uncovering the molecular basis of male infertility and developing new diagnostic tools and assisted reproductive technologies that may help infertile patients through more effective treatment techniques. This article is categorized under: Reproductive System Diseases > Environmental Factors Infectious Diseases > Stem Cells and Development Reproductive System Diseases > Molecular and Cellular Physiology.

Globozoospermia: A Case Report and Systematic Review of Literature

PURPOSE

Globozoospermia is a genetic syndrome characterized by the presence of round-headed spermatozoa and infertility due to the inability of these spermatozoa to fertilize the oocyte. In this article, we present the clinical case of a young globozoospermic patient with a new, not yet described mutation of the DPY19L2 gene. We also performed a systematic review of the literature on gene mutations, the outcome of assisted reproductive techniques, and the risk of transmission of abnormalities to the offspring in patients with globozoospermia and made recommendations to offer a more appropriate clinical management of these patients.

MATERIALS AND METHODS

We performed a systematic search in the PubMed, Google Scholar, and Scopus databases from their inception to December 2021. The search strategy included the combination of the following Medical Subjects Headings (MeSH) terms and keywords: "globozoospermia", "round-headed spermatozoa", "round head spermatozoa", "intracytoplasmic sperm injection", "ICSI", "offspring", "child health", "assisted reproductive technique outcome". All the eligible studies were selected following the PECOS (Population, Exposure, Comparison/Comparator, Outcomes, Study design) model. The quality of included studies was assessed by applying the "Cambridge Quality Checklists".

RESULTS

The main genes involved in the pathogenesis of globozoospermia are DPY19L2, SPATA16, PICK1, GGN, SPACA1, ZPBP, CCDC62, and CCNB3 genes. Other genes could also play a role. These include C2CD6, C7orf61, CCIN, DNH17, DNH6, PIWIL4, and CHPT1. Globozoospermic patients should undergo ART to achieve fertility. In particular, intracytoplasmic sperm injection with assisted oocyte activation or intracytoplasmic morphologically-selected sperm injection appears to be associated with a higher success rate. Patients with globozoospermia should also be evaluated for the high rate of sperm aneuploidy which appears to influence the success rate of ART but does not appear to be associated with an increased risk of transmission of genetic abnormalities to offspring.

CONCLUSIONS

This systematic review summarizes the evidence on the gene panel to be evaluated, ICSI outcomes, and the health of the offspring in patients with globozoospermia. Evidence-based recommendations on the management of patients with globozoospermia are provided.

Application of CRISPR/Cas Technology in Spermatogenesis Research and Male Infertility Treatment

As the basis of animal reproductive activity, normal spermatogenesis directly determines the efficiency of livestock production. An in-depth understanding of spermatogenesis will greatly facilitate animal breeding efforts and male infertility treatment. With the continuous development and application of gene editing technologies, they have become valuable tools to study the mechanism of spermatogenesis. Gene editing technologies have provided us with a better understanding of the functions and potential mechanisms of action of factors that regulate spermatogenesis. This review summarizes the applications of gene editing technologies, especially CRISPR/Cas9, in deepening our understanding of the function of spermatogenesis-related genes and disease treatment. The problems of gene editing technologies in the field of spermatogenesis research are also discussed.

Awareness and reporting of globozoospermia among in vitro fertilization and andrology laboratories: A national survey

Globozoospermia (GZ) is a rare disorder found in less than 0.1% of infertile men in which spermatozoa lack acrosomes necessary for penetration of an oocyte. While methods have been demonstrated to allow globozoospermic men to achieve a viable pregnancy with their partner, the Wold Health Organization considers identifying and reporting GZ on semen analysis to be 'important'. Our study aims to determine if and to what extent in vitro fertilization (IVF) laboratories nationwide recognize and report GZ on semen analysis reports. We constructed an IRB-approved survey sent nationwide to IVF and andrology clinic laboratory directors listed by the Society for Assisted Reproductive Technology and/or the American Society for Reproductive Medicine. Results from the survey were de-identified for analysis. A total of 490 surveys were sent with a response rate of 10% (n = 51). Most respondents (66%) practiced in a private, rather than academic, setting. A majority of respondents were confident in their technicians' knowledge of GZ (86%) and ability to identify it on a sample (94%). However, only half of respondents noted a space to report the concern for GZ to the ordering physician, and 25% of respondents did not feel their clinic was able to identify patients where there is a concern for GZ. Similarly, 84% of respondents did not report a percent of acrosome-deficient sperm. Less than half of respondents reported that their clinic has previously diagnosed GZ. Though the majority of respondents felt that their laboratory technicians would be able to identify GZ, a significant minority felt that their clinic did not have means to be able to report concern for GZ. This may be due to the absence of a proper channel to report a concern for GZ, a lack of knowledge about the condition, or failure to distinguish GZ from a broader reported percentage of morphologically abnormal sperm. Given evidence that the diagnosis of GZ may be under-reported in the United States, there should be a national standard for laboratory technicians to be trained to recognize GZ and be able to report their suspicion to the ordering clinician.

Advanced molecular approaches in male infertility diagnosis

In the recent years a special attention has been given to a major health concern namely to male infertility, defined as the inability to conceive after 12 months of regular unprotected sexual intercourse, taken into account the statistics that highlight that sperm counts have dropped by 50-60% in recent decades. According to the WHO, infertility affects approximately 9% of couples globally, and the male factor is believed to be present in roughly 50% of cases, with exclusive responsibility in 30%. The aim of this manuscript is to present an evidence-based approach for diagnosing male infertility that includes finding new solutions for diagnosis and critical outcomes, retrieving up-to-date studies and existing guidelines. The diverse factors that induce male infertility generated in a vast amount of data that needed to be analysed by a clinician before a decision could be made for each individual. Modern medicine faces numerous obstacles as a result of the massive amount of data generated by the molecular biology discipline. To address complex clinical problems, vast data must be collected, analysed, and used, which can be very challenging. The use of artificial intelligence (AI) methods to create a decision support system can help predict the diagnosis and guide treatment for infertile men, based on analysis of different data as environmental and lifestyle, clinical (sperm count, morphology, hormone testing, karyotype, etc.) and "omics" bigdata. Ultimately, the development of AI algorithms will assist clinicians in formulating diagnosis, making treatment decisions, and predicting outcomes for assisted reproduction techniques.

FAM71F1 binds to RAB2A and RAB2B and is essential for acrosome formation and male fertility in mice

The acrosome is a cap-shaped, Golgi-derived membranous organelle that is located over the anterior of the sperm nucleus and highly conserved throughout evolution. Although morphological changes during acrosome biogenesis in spermatogenesis have been well described, the molecular mechanism underlying this process is still largely unknown. Family with sequence similarity 71, member F1 and F2 (FAM71F1 and FAM71F2) are testis-enriched proteins that contain a RAB2B-binding domain, a small GTPase involved in vesicle transport and membrane trafficking. Here, by generating mutant mice for each gene, we found that Fam71f1 is essential for male fertility. In Fam71f1-mutant mice, the acrosome was abnormally expanded at the round spermatid stage, likely because of enhanced vesicle trafficking. Mass spectrometry analysis after immunoprecipitation indicated that, in testes, FAM71F1 binds not only RAB2B, but also RAB2A. Further study suggested that FAM71F1 binds to the GTP-bound active form of RAB2A/B, but not the inactive form. These results indicate that a complex of FAM71F1 and active RAB2A/B suppresses excessive vesicle trafficking during acrosome formation.

Will whole-genome sequencing become the first-line genetic analysis for male infertility in the near future?

Whereas the initially strategy for the genetic analysis of male infertility was based on a candidate gene approach, the development of next-generation sequencing technologies (such as whole-exome sequencing (WES)) provides an opportunity to analyze many genes in a single procedure. In order to recommend WES or whole-genome sequencing (WGS) after genetic counselling, an objective evaluation of the current genetic screening strategy for male infertility is required, even if, at present, we have to take into consideration the complexity of such a procedure, not discussed in this commentary.

Molecular Analysis of DPY19L2, PICK1 and SPATA16 in Italian Unrelated Globozoospermic Men

This study aims to evaluate genetic contribution and sperm DNA fragmentation (SDF) in a cohort of 18 unrelated globozoospermic Italian men (Group G). Semen samples were assessed according to the WHO 2010 Laboratory Manual and compared with 31 fertile controls. We focused our genetic analysis on the exons of the main globozoospermia-associated genes, performing qualitative PCR to assess deletion of DPY19L2 and sequencing to detect mutations of SPATA16 and PICK1. SDF was evaluated using the TUNEL assay. In Group G, 10 patients had a complete form of globozoospermia, whereas 8 patients had a partial form. Molecular analysis revealed deletion of DPY19L2 in six of the patients, all of them with complete globozoospermia, while no mutations were found in the examined exons of PICK1 and SPATA16. TUNEL analysis showed a higher SDF% in Group G. Our findings confirm DPY19L2 defects as the most frequent genetic alteration in Italian patients contributing to globozoospermic phenotypes. Furthermore, spermatozoa with acrosomal defects could also display high levels of SDF as a possible consequence of abnormally remodeled chromatin. The possible effect on offspring of chromatin structure abnormalities and altered DNA integrity should be carefully evaluated by clinicians, especially regarding the feasibility and safety of artificial reproductive techniques, which represent the only treatment that allows these patients to conceive.

Disease gene discovery in male infertility: past, present and future

Identifying the genes causing male infertility is important to increase our biological understanding as well as the diagnostic yield and clinical relevance of genetic testing in this disorder. While significant progress has been made in some areas, mainly in our knowledge of the genes underlying rare qualitative sperm defects, the same cannot be said for the genetics of quantitative sperm defects. Technological advances and approaches in genomics are critical for the process of disease gene identification. In this review we highlight the impact of various technological developments on male infertility gene discovery as well as functional validation, going from the past to the present and the future. In particular, we draw attention to the use of unbiased genomics approaches, the development of increasingly relevant functional assays and the importance of large-scale international collaboration to advance disease gene identification in male infertility.

Genetics of teratozoospermia: Back to the head

Spermatozoa are polarized cells with a head and a flagellum joined by the connecting piece. Head integrity is critical for normal sperm function, and head defects consistently lead to male infertility. Abnormalities of the sperm head are among the most severe and characteristic sperm defects. Patients presenting with a monomorphic head sperm defects such as globozoospermia or marcrozoospermia were analyzed permitting to identify several key genes for spermatogenesis such as AURKC and DPY19L2. The study of patients with other specific sperm head defects such as acephalic spermatozoa have also enabled the identification of new infertility genes such as SUN5. Here, we review the genetic causes leading to morphological defects of sperm head. Advances in the genetics of male infertility are necessary to improve the management of infertility and will pave the road towards future strategies of treatments, especially for patients with the most severe phenotype as sperm head defects.

Molecular genetics of infertility: loss-of-function mutations in humans and corresponding knockout/mutated mice

BACKGROUND

Infertility is a major issue in human reproductive health, affecting an estimated 15% of couples worldwide. Infertility can result from disorders of sex development (DSD) or from reproductive endocrine disorders (REDs) with onset in infancy, early childhood or adolescence. Male infertility, accounting for roughly half of all infertility cases, generally manifests as decreased sperm count (azoospermia or oligozoospermia), attenuated sperm motility (asthenozoospermia) or a higher proportion of morphologically abnormal sperm (teratozoospermia). Female infertility can be divided into several classical types, including, but not limited to, oocyte maturation arrest, premature ovarian insufficiency (POI), fertilization failure and early embryonic arrest. An estimated one half of infertility cases have a genetic component; however, most genetic causes of human infertility are currently uncharacterized. The advent of high-throughput sequencing technologies has greatly facilitated the identification of infertility-associated gene mutations in patients over the past 20 years.

OBJECTIVE AND RATIONALE

This review aims to conduct a narrative review of the genetic causes of human infertility. Loss-of-function mutation discoveries related to human infertility are summarized and further illustrated in tables. Corresponding knockout/mutated animal models of causative genes for infertility are also introduced.

SEARCH METHODS

A search of the PubMed database was performed to identify relevant studies published in English. The term 'mutation' was combined with a range of search terms related to the core focus of the review: infertility, DSD, REDs, azoospermia or oligozoospermia, asthenozoospermia, multiple morphological abnormalities of the sperm flagella (MMAF), primary ciliary dyskinesia (PCD), acephalic spermatozoa syndrome (ASS), globozoospermia, teratozoospermia, acrosome, oocyte maturation arrest, POI, zona pellucida, fertilization defects and early embryonic arrest.

OUTCOMES

Our search generated ∼2000 records. Overall, 350 articles were included in the final review. For genetic investigation of human infertility, the traditional candidate gene approach is proceeding slowly, whereas high-throughput sequencing technologies in larger cohorts of individuals is identifying an increasing number of causative genes linked to human infertility. This review provides a wide panel of gene mutations in several typical forms of human infertility, including DSD, REDs, male infertility (oligozoospermia, MMAF, PCD, ASS and globozoospermia) and female infertility (oocyte maturation arrest, POI, fertilization failure and early embryonic arrest). The causative genes, their identified mutations, mutation rate, studied population and their corresponding knockout/mutated mice of non-obstructive azoospermia, MMAF, ASS, globozoospermia, oocyte maturation arrest, POI, fertilization failure and early embryonic arrest are further illustrated by tables. In this review, we suggest that (i) our current knowledge of infertility is largely obtained from knockout mouse models; (ii) larger cohorts of clinical cases with distinct clinical characteristics need to be recruited in future studies; (iii) the whole picture of genetic causes of human infertility relies on both the identification of more mutations for distinct types of infertility and the integration of known mutation information; (iv) knockout/mutated animal models are needed to show whether the phenotypes of genetically altered animals are consistent with findings in human infertile patients carrying a deleterious mutation of the homologous gene; and (v) the molecular mechanisms underlying human infertility caused by pathogenic mutations are largely unclear in most current studies.

WILDER IMPLICATIONS

It is important to use our current understanding to identify avenues and priorities for future research in the field of genetic causes of infertility as well as to apply mutation knowledge to risk prediction, genetic diagnosis and potential treatment for human infertility.

Genetic analyses of a large cohort of infertile patients with globozoospermia, DPY19L2 still the main actor, GGN confirmed as a guest player

Globozoospermia is a rare phenotype of primary male infertility inducing the production of round-headed spermatozoa without acrosome. Anomalies of DPY19L2 account for 50-70% of all cases and the entire deletion of the gene is by far the most frequent defect identified. Here, we present a large cohort of 69 patients with 20-100% of globozoospermia. Genetic analyses including multiplex ligation-dependent probe amplification, Sanger sequencing and whole-exome sequencing identified 25 subjects with a homozygous DPY19L2 deletion (36%) and 14 carrying other DPY19L2 defects (20%). Overall, 11 deleterious single-nucleotide variants were identified including eight novel and three already published mutations. Patients with a higher rate of round-headed spermatozoa were more often diagnosed and had a higher proportion of loss of function anomalies, highlighting a good genotype phenotype correlation. No gene defects were identified in patients carrying < 50% of globozoospermia while diagnosis efficiency rose to 77% for patients with > 50% of globozoospermia. In addition, results from whole-exome sequencing were scrutinized for 23 patients with a DPY19L2 negative diagnosis, searching for deleterious variants in the nine other genes described to be associated with globozoospermia in human (C2CD6, C7orf61, CCDC62, CCIN, DNAH17, GGN, PICK1, SPATA16, and ZPBP1). Only one homozygous novel truncating variant was identified in the GGN gene in one patient, confirming the association of GGN with globozoospermia. In view of these results, we propose a novel diagnostic strategy focusing on patients with at least 50% of globozoospermia and based on a classical qualitative PCR to detect DPY19L2 homozygous deletions. In the absence of the latter, we recommend to perform whole-exome sequencing to search for defects in DPY19L2 as well as in the other previously described candidate genes.

Identification of a novel deletion mutation in DPY19L2 from an infertile patient with globozoospermia: a case report

Background

Male infertility is an increasing medical concern worldwide. In most cases, genetic factors are considered as the main cause of the disease. Globozoospermia (MIM102530) (also known as round-headed sperm) is a rare and severe malformed spermatospermia caused by acrosome deficiency or severe malformation. A subset of genetic mutations, such as DNAH6, SPATA16, DPY19L2, PICK1, and CCIN related to globozoospermia, have been reported in the past few years. The DPY19L2 mutation is commonly found in patients with globozoospermia. Herein, a 180-kbp homozygote deletion at 12q14.2 (g.63950001–64130000) was identified by copy number variation sequencing (CNVseq) in a patient with a globozoospermia, including the complete deletion of DPY19L2.

Case presentation

A 27-year-old patient at the First Affiliated Hospital of Xiamen University was diagnosed with infertility because, despite normal sexual activity for 4 years, his wife did not conceive. The patient was in good health with no obvious discomfort, no history of adverse chemical exposure, and no vices, such as smoking and drinking. The physical examination revealed normal genital development. However, semen tests showed a normal sperm count of 0% and the morphology was the round head. Sperm cytology showed that acrosomal enzyme was lower than normal. Reproductive hormones were in the normal range. B ultrasound did not show any abnormal seminal vesicle, prostate, bilateral testis, epididymis, and spermatic veins. The karyotype was normal, 46, XY, and no microdeletion of Y chromosome was detected. However, a homozygous deletion mutation was found in DPY19L2, which was further diagnosed as globozoospermia.

Conclusions

The present study reported a male infertility patient who was diagnosed with globozoospermia. The analysis of gene mutations revealed that DPY19L2 had a homozygous mutation, which was the primary cause of globozoospermia.

Transcriptome profiling of developing testes and spermatogenesis in the Mongolian horse

BACKGROUND

Horse testis development and spermatogenesis are complex physiological processes.

METHODS

To study these processes, three immature and three mature testes were collected from the Mongolian horse, and six libraries were established using high-throughput RNA sequencing technology (RNA-Seq) to screen for genes related to testis development and spermatogenesis.

RESULTS

A total of 16,237 upregulated genes and 8,641 downregulated genes were detected in the testis of the Mongolian horse. These genes play important roles in different developmental stages of spermatogenesis and testicular development. Five genes with alternative splicing events that may influence spermatogenesis and development of the testis were detected. GO (Gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses were performed for functional annotation of the differentially expressed genes. Pathways related to "spermatogenesis," male gamete generation," "spermatid development" and "oocyte meiosis" were significantly involved in different stages of testis development and spermatogenesis.

CONCLUSION

Genes, pathways and alternative splicing events were identified with inferred functions in the process of spermatogenesis in the Mongolian horse. The identification of these differentially expressed genetic signatures improves our understanding of horse testis development and spermatogenesis.

Novel DPY19L2 variants in globozoospermic patients and the overcoming this male infertility

Globozoospermia has been reported to be a rare but severe causation of male infertility, which results from the failure of acrosome biogenesis and sperm head shaping. Variants of dpy-19-like 2 (DPY19L2) are highly related to globozoospermia, but related investigations have been mainly performed in patients from Western countries. Here, we performed a screening of DPY19L2 variants in a cohort of Chinese globozoospermic patients and found that five of nine patients carried DPY19L2 deletions and the other four patients contained novel DPY19L2 point mutations, as revealed by whole-exome sequencing. Patient 3 (P3) contained a heterozygous variant (c.2126+5G>A), P6 contained a homozygous nonsense mutation (c.1720C>T, p.Arg574^*), P8 contained compound heterozygous variants (c.1182-1184delATC, p.Leu394_Ser395delinsPhe; c.368A>T, p.His123Arg), and P9 contained a heterozygous variant (c.1182-1184delATCTT, frameshift). We also reported intracytoplasmic sperm injection (ICSI) outcomes in the related patients, finding that ICSI followed by assisted oocyte activation (AOA) with calcium ionophore achieved high rates of live births. In summary, the infertility of these patients results from DPY19L2 dysfunction and can be treated by ICSI together with AOA.

A framework for high-resolution phenotyping of candidate male infertility mutants: from human to mouse

Male infertility is a heterogeneous condition of largely unknown etiology that affects at least 7% of men worldwide. Classical genetic approaches and emerging next-generation sequencing studies support genetic variants as a frequent cause of male infertility. Meanwhile, the barriers to transmission of this disease mean that most individual genetic cases will be rare, but because of the large percentage of the genome required for spermatogenesis, the number of distinct causal mutations is potentially large. Identifying bona fide causes of male infertility thus requires advanced filtering techniques to select for high-probability candidates, including the ability to test causality in animal models. The mouse remains the gold standard for defining the genotype-phenotype connection in male fertility. Here, we present a best practice guide consisting of (a) major points to consider when interpreting next-generation sequencing data performed on infertile men, and, (b) a systematic strategy to categorize infertility types and how they relate to human male infertility. Phenotyping infertility in mice can involve investigating the function of multiple cell types across the testis and epididymis, as well as sperm function. These findings will feed into the diagnosis and treatment of male infertility as well as male health broadly.

Comparison of Human Oocyte Activation Between Round-Headed Sperm Injection Followed by Calcium Ionophore Treatment and Normal Sperm Injection in a Patient With Globozoospermia

Fertilization failure is common in patients with round-headed sperm, a form of globozoospermia. Artificial oocyte activation is able to assist oocyte fertilization after sperm injection in these patients. Comparisons between oocyte fertilization with or without calcium ionophore have been reported in patients with round-headed sperm. However, no comparison has been reported between round-headed sperm injection followed by calcium ionophone activation and normal sperm injection. In this case report, half of oocytes from a patient were injected with her partner's round-headed sperm followed by calcium ionophore activation, and the other half of oocytes were injected with a donor sperm without calcium ionophore activation. The injected oocytes were cultured to examine fertilization, embryo development, and embryonic aneuploidies in the resulting blastocysts. The fertilization rate was lower in round-headed sperm injected oocytes (3/6) than that in donor sperm injected oocytes (5/6), but rates of blastocyst and aneuploidies were similar in the resulting embryos between the two groups. A euploid blastocyst resulted from round-headed sperm injection was transferred, and a healthy baby was delivered. These results indicate that calcium ionophore treatment can assist oocyte activation in patients with round-headed sperm, but its efficiency to activate oocytes is lower than that induced by a normal sperm injection. However, embryo development and chromosome integrity may not be affected by calcium ionophore treatment.

Deletion of dpy-19 like 2 (DPY19L2) gene is associated with total but not partial globozoospermia

The dpy-19 like 2 (DPY19L2) gene is the most common genetic cause of globozoospermia characterised by the production of round-headed spermatozoa without an acrosome. The present study was performed on 63 men with globozoospermia and 41 normozoospermic individuals to evaluate the frequency of the DPY19L2 gene and exons; deletion and genetic changes in exons 1, 5, 7–11, 19, 21 and interval introns; and some epidemiological factors (e.g. varicocele, smoking, drug use, alcohol consumption and a family history of infertility). Homozygous deletion of DPY19L2 was identified in 35% of men with globozoospermia. Exon 7 was deleted in 4.8% of men with globozoospermia in which DPY19L2 was not deleted. No genetic variations were observed within the DPY19L2 exons examined, but five intronic polymorphisms were detected: 1054–77T&gt;C in intron 9, 1131+65T&gt;C and 1131+53A&gt;G in intron 10 and 1218+22T&gt;C and 1218+73T&gt;C in intron 11. There were significant differences in the frequency of 1054–77T&gt;C and 1218+22T&gt;C polymorphisms between the globozoospermic and normozoospermic groups. In addition, there were significant differences between the two groups in sperm count, sperm motility, a history of infertility in the family and varicocele. Based on these findings, DPY19L2 deletion is the major cause of total globozoospermia and there is no association between exons 1, 5, 8–11, 19 and 21 polymorphisms of the DPY19L2 gene in the occurrence of this defect.

Globozoospermia syndrome: An update

Among the factors involved in male infertility, there is a rare morphology disorder called "globozoospermia" that is classified into total globozoospermia and partial globozoospermia (type I and type II, respectively). This syndrome is primarily characterised by the presence of round-headed spermatozoa with cytoskeleton defects around the nucleus and no acrosome. Current data support the negative correlation between globozoospermia and conventional intracytoplasmic sperm injection (ICSI) outcomes, revealing the need for the management of patients undergoing assisted reproduction technology (ART) through more effective treatment techniques. This review highlights the most important characteristics of globozoospermia such as sperm parameters, DNA/chromatin integrity and sperm DNA fragmentation (SDF), as well as genetic features based on the latest knowledge. Additionally, we looked into current progress on fertilisation potential and possible treatment strategies for patients presenting with globozoospermia.

A Novel Scoring System for Pivotal Autophagy-Related Genes Predicts Outcomes after Chemotherapy in Advanced Ovarian Cancer Patients

BACKGROUND

In the clinical practice of ovarian cancer, the application of autophagy, an important regulator of carcinogenesis and chemoresistance, is still limited. This study aimed to establish a scoring system based on expression profiles of pivotal autophagy-related (ATG) genes in patients with stage III/IV ovarian cancer who received chemotherapy.

METHODS

Data of ovarian serous cystadenocarcinoma in The Cancer Genome Atlas (TCGA-OV) were used as training dataset. Two validation datasets comprised patients in a Chinese local database and a dataset from the Gene Expression Omnibus (GEO). ATG genes significantly (P < 0.1) associated with overall survival (OS) were selected and aggregated into an ATG scoring scale, of which the abilities to predict OS and recurrence-free survival (RFS) were examined.

RESULTS

Forty-three ATG genes were selected to develop the ATG score. In TCGA-OV, patients with lower ATG scores had better OS [HR = 0.41; 95% confidence interval (CI), 0.26-0.65; P < 0.001] and RFS [HR = 0.47; 95% CI, 0.27-0.82; P = 0.007]. After complete or partial remission to primary therapy, the rate of recurrence was 47.2% in the low-score group and 68.3% in the high-score group (odds ratio = 0.42; 95% CI, 0.18-0.92; P = 0.03). Such findings were verified in the two validation datasets.

CONCLUSIONS

We established a novel scoring system based on pivotal ATG genes, which accurately predicts the outcomes of patients with advanced ovarian cancer after chemotherapy.

IMPACT

The present ATG scoring system may provide a novel perspective and a promising tool for the development of personalized therapy in the future.

Altered three-dimensional organization of sperm genome in DPY19L2-deficient globozoospermic patients

PURPOSE

To explore the three-dimensional (3D) organization of sperm genome in DPY19L2-deficient globozoospermic patients speculating a link between DPY19L2 and genome organization of sperm nucleus.

METHODS

This is a study of chromatin organization in DPY19L2-deficient globozoospermic patients and healthy donors using three-dimensional fluorescence in situ hybridization (3D-FISH) combined with confocal laser scanning microscopy followed by 3D image analysis. The 3D structures of sperm nuclei, chromocenter, telomeric regions and chromosome territories (CTs), were reconstructed using IMARIS software, and the relative radial position for each individual signal was calculated. Statistical analysis used a non-parametric Mann-Whitney test was appropriate with significance at p < 0.05.

RESULTS

DPY19L2-deficient globozoospermic patients display impaired sperm chromocenter organization resulting in an increased number of chromocenters (5.4 vs 3.5; p < 0.0001). Moreover, radial positions of telomeres are modified with a more central position in globozoospermic nuclei. 3D-FISH analysis of five chromosome territories (CTs) (X, Y, 7, 17, 18) showed that DPY19L2-deficient globozoospermic sperm nuclei display altered spatial organization of CT X, CT 7 and CT 18.

CONCLUSIONS

Our findings strengthen the hypothesis that DPY19L2 might be considered as a LINC-like protein having a crucial role in the organization of nuclear chromatin in sperm nucleus through its interaction with nuclear lamina. Our results might also explain defective embryonic development after intracytoplasmic sperm injection (ICSI) performed with DPY19L2-deficient globozoospermic sperm.

An Overview of The Globozoospermia as A Multigenic Identified Syndrome

Acrosome plays an integral role during fertilization and its absence in individuals with globozoospermia leads to failure of in vitro fertilization (IVF) and oocyte activation post-intracytoplasmic sperm injection (ICSI). A variety of processes, organelles and structures are involved in acrosome biogenesis including, trans-golgi network (TGN), acroplaxome and cellular trafficking. This review aims to explain roles of related signals and molecules involved in this process and also describe how their absence in form of mutation, deletion and knockout model may lead to phe- nomenon referred to globozoospermia.

AU040320 deficiency leads to disruption of acrosome biogenesis and infertility in homozygous mutant mice

Study of knockout (KO) mice has helped understand the link between many genes/proteins and human diseases. Identification of infertile KO mice provides valuable tools to characterize the molecular mechanisms underlying gamete formation. The KIAA0319L gene has been described to have a putative association with dyslexia; surprisingly, we observed that homozygous KO males for AU040320, KIAA0319L ortholog, are infertile and present a globozoospermia-like phenotype. Mutant spermatozoa are mostly immotile and display a malformed roundish head with no acrosome. In round spermatids, proacrosomal vesicles accumulate close to the acroplaxome but fail to coalesce into a single acrosomal vesicle. In wild-type mice AU040320 localises to the trans-Golgi-Network of germ cells but cannot be detected in mature acrosomes. Our results suggest AU040320 may be necessary for the normal formation of proacrosomal vesicles or the recruitment of cargo proteins required for downstream events leading to acrosomal fusion. Mutations in KIAA0319L could lead to human infertility; we screened for KIAA0319L mutations in a selected cohort of globozoospermia patients in which no genetic abnormalities have been previously identified, but detected no pathogenic changes in this particular cohort.

The involvement of the nuclear lamina in human and rodent spermiogenesis: a systematic review

The nuclear lamina (NL) is a filamentous protein meshwork, composed essentially of lamins, situated between the inner nuclear membrane and the chromatin. The NL is a component of the nuclear envelope, interacts with a wide range of proteins and is required for normal nuclear structure and physiological development. During spermiogenesis the spermatid nucleus is elongated, and dramatically reduced in size with protamines replacing histones to produce a highly compacted chromatin. There is mounting evidence from studies in human and rodent, that the NL plays an important role in mammalian spermatid differentiation during spermiogenesis. In this review, we summarize and discuss the data available in the literature regarding the involvement of lamins and their direct or indirect partners in normal and abnormal human spermiogenesis.

Creation of knock out and knock in mice by CRISPR/Cas9 to validate candidate genes for human male infertility, interest, difficulties and feasibility

High throughput sequencing (HTS) and CRISPR/Cas9 are two recent technologies that are currently revolutionizing biological and clinical research. Both techniques are complementary as HTS permits to identify new genetic variants and genes involved in various pathologies and CRISPR/Cas9 permits to create animals or cell models to validate the effect of the identified variants, to characterize the pathogeny of the identified variants and the function of the genes of interest and ultimately to provide ways of correcting the molecular defects. We analyzed a cohort of 78 infertile men presenting with multiple morphological anomalies of the sperm flagella (MMAF), a severe form of male infertility. Using whole exome sequencing (WES), homozygous mutations in autosomal candidate genes were identified in 63% of the tested subjects. We decided to produce by CRISPR/cas9 four knock-out (KO) and one knock-in (KI) mouse lines to confirm these results and to increase our understanding of the physiopathology associated with these genetic variations. Overall 31% of the live pups obtained presented a mutational event in one of the targeted regions. All identified events were insertions or deletions localized near the PAM sequence. Surprisingly we observed a high rate of germline mosaicism as 30% of the F1 displayed a different mutation than the parental event characterized on somatic tissue (tail), indicating that CRISPR/Cas9 mutational events kept happening several cell divisions after the injection. Overall, we created mouse models for 5 distinct loci and in each case homozygous animals could be obtained in approximately 6 months. These results demonstrate that the combined use of WES and CRISPR/Cas9 is an efficient and timely strategy to identify and validate mutations responsible for infertility phenotypes in human.

Human Globozoospermia-Related Gene Spata16 Is Required for Sperm Formation Revealed by CRISPR/Cas9-Mediated Mouse Models

A recent genetic analysis of infertile globozoospermic patients identified causative mutations in three genes: a protein interacting with C kinase 1 (PICK1), dpy 19-like 2 (DPY19L2), and spermatogenesis associated 16 (SPATA16). Although mouse models have clarified the physiological functions of Pick1 and Dpy19l2 during spermatogenesis, Spata16 remains to be determined. Globozoospermic patients carried a homozygous point mutation in SPATA16 at 848G→A/R283Q. We generated CRISPR/Cas9-mediated mutant mice with the same amino acid substitution in the fourth exon of Spata16 to analyze the mutation site at R284Q, which corresponded with R283Q of mutated human SPATA16. We found that the point mutation in Spata16 was not essential for male fertility; however, deletion of the fourth exon of Spata16 resulted in infertile male mice due to spermiogenic arrest but not globozoospermia. This study demonstrates that Spata16 is indispensable for male fertility in mice, as well as in humans, as revealed by CRISPR/Cas9-mediated mouse models.

Genetic abnormalities leading to qualitative defects of sperm morphology or function

Infertility, defined by the inability of conceiving a child after 1 year is estimated to concern approximately 50 million couples worldwide. As the male gamete is readily accessible and can be studied by a simple spermogram it is easier to subcategorize male than female infertility. Subjects with a specific sperm phenotype are more likely to have a common origin thus facilitating the search for causal factors. Male infertility is believed to be often multifactorial and caused by both genetic and extrinsic factors, but severe cases of male infertility are likely to have a predominant genetic etiology. Patients presenting with a monomorphic teratozoospermia such as globozoospermia or macrospermia with more than 85% of the spermatozoa presenting this specific abnormality have been analyzed permitting to identify several key genes for spermatogenesis such as AURKC and DPY19L2. The study of patients with other specific sperm anomalies such as severe alteration of sperm motility, in particular multiple morphological anomalies of the sperm flagella (MMAF) or sperm unability to fertilize the oocyte (oocyte activation failure syndrome) has also enable the identification of new infertility genes. Here we review the recent works describing the identification and characterization of gene defects having a direct qualitative effect on sperm morphology or function.

Biogenesis of sperm acrosome is regulated by pre-mRNA alternative splicing of Acrbp in the mouse

Proper biogenesis of a sperm-specific organelle, the acrosome, is essential for gamete interaction. An acrosomal matrix protein, ACRBP, is known as a proacrosin-binding protein. In mice, two forms of ACRBP, wild-type ACRBP-W and variant ACRBP-V5, are generated by pre-mRNA alternative splicing of Acrbp Here, we demonstrate the functional roles of these two ACRBP proteins. ACRBP-null male mice lacking both proteins showed a severely reduced fertility, because of malformation of the acrosome. Notably, ACRBP-null spermatids failed to form a large acrosomal granule, leading to the fragmented structure of the acrosome. The acrosome malformation was rescued by transgenic expression of ACRBP-V5 in ACRBP-null spermatids. Moreover, exogenously expressed ACRBP-W blocked autoactivation of proacrosin in the acrosome. Thus, ACRBP-V5 functions in the formation and configuration of the acrosomal granule during early spermiogenesis. The major function of ACRBP-W is to retain the inactive status of proacrosin in the acrosome until acrosomal exocytosis.

Mutations of the aurora kinase C gene causing macrozoospermia are the most frequent genetic cause of male infertility in Algerian men

Klinefelter syndrome and Y-chromosomal microdeletion analyses were once the only two genetic tests offered to infertile men. Analyses of aurora kinase C (AURKC) and DPY19L2 are now recommended for patients presenting macrozoospermia and globozoospermia, respectively, two rare forms of teratozoospermia particularly frequent among North African men. We carried out genetic analyses on Algerian patients, to evaluate the prevalence of these syndromes in this population and to compare it with the expected frequency of Klinefelter syndrome and Y-microdeletions. We carried out a retrospective study on 599 consecutive patients consulting for couple infertility at the assisted reproduction unit of the Ibn Rochd Clinique, Constantine, Algeria. Abnormal sperm parameters were observed in 404 men. Fourteen and seven men had typical macrozoospermia and globozoospermia profiles, respectively. Molecular diagnosis was carried out for these patients, for the AURKC and DPY19L2 genes. Eleven men with macrozoospermia had a homozygous AURKC mutation (79%), corresponding to 2.7% of all patients with abnormal spermograms. All the men with globozoospermia studied (n = 5), corresponding to 1.2% of all infertile men, presented a homozygous DPY19L2 deletion. By comparison, we would expect 1.6% of the patients in this cohort to have Klinefelter syndrome and 0.23% to have Y-microdeletion. Our findings thus indicate that AURKC mutations are more frequent than Klinefelter syndrome and constitute the leading genetic cause of infertility in North African men. Furthermore, we estimate that AURKC and DPY19L2 molecular defects are 10 and 5 times more frequent, respectively, than Y-microdeletions.

Assessment of DPY19L2 Deletion in Familial and Non-Familial Individuals with Globozoospermia and DPY19L2 Genotyping

Background

Globozoospermia is a rare syndrome with an incidence of less than 0.1% among infertile men. Researchers have recently identified a large deletion, about 200 kbp, encompassing the whole length of DPY19L2 or mutations in SPATA16 and PICK1 genes associated with globozoospermia. The aim of this study was to analyze the DPY19L2 gene deletion using polymerase chain reaction technique for the exons 1, 48, 11 and 22 as well as break point (BP) “a” in globozoospermic men.

Materials and Methods

In this experimental study, genome samples were collected from 27 men with globozoospermia (cases) and 36 fertile individuals (controls), and genomic analysis was carried out on each sample.

Results

Deletion of DPY19L2 gene accounted for 74% of individuals with globozoospermia. DPY19L2 gene deletion was considered as the molecular pathogenic factor for the onset of globozoospermia in infertile men. By quantitative real-time polymerase chain reaction (qPCR), we genotyped DPY19L2 deletion and identified carriers within the population.

Conclusion

This technique may be considered as a method for family counseling and has the potential to be used as a pre-implantation genetic diagnosis, especially in ethnic community with high rate of consanguineous marriages.

Sun proteins and Dpy19l2 forming LINC-like links are critical for spermiogenesis

Summary: In this response to Pasch et al.’s (2015) discovery that Sun4 is essential for sperm head formation, the authors highlight that like Sun4, Dpy19l2 has a likely LINK-like function and that it also plays a crucial role in spermiogenesis and male infertility.

Identification of a new DPY19L2 mutation and a better definition of DPY19L2 deletion breakpoints leading to globozoospermia

STUDY HYPOTHESIS

The purpose of this study was to analyze DPY19L2 sequence variants to investigate the mechanism leading to the entire DPY19L2 deletion in a large cohort of infertile globozoospermic patients.

STUDY FINDING

An improved analysis of the DPY19L2 deletion breakpoints (BPs) allowed us to identify two BPs located in a small 1 kb region and to more precisely localize the BPs reported previously.

WHAT IS KNOWN ALREADY

Three genes [spermatogenesis associated 16 (SPATA16), protein interacting with PRKCA (PICK1) and DPY19L2] were previously correlated with globozoospermia, but a homozygous deletion of the entire DPY19L2 was identified as the most frequent alteration causing this phenotype. In addition, several point mutations in this gene were reported. In previous work, we have identified nine BPs for the DPY19L2 deletion clustered in two hotspot regions, while others reported a total of five BPs.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

We screened for the DPY19L2 deletion and for mutations in the DPY19L2, SPATA16 and PICK1 genes in a cohort of 21 Tunisian globozoospermic patients. In order to characterize the DPY19L2 deletion BPs, we sequenced a 2 kb fragment on low copy repeat (LCR) 1 and LCR2 in Tunisian fertile controls to distinguish between single-nucleotide polymorphisms (SNPs) and LCR-specific markers.

MAIN RESULTS AND THE ROLE OF CHANCE

Molecular analyses performed on 18 genetically independent individuals showed that 11 (61.1%) were homozygous for the DPY19L2 deletion, 2 (11.1%) were homozygous for the non-synonymous mutation (p.R298C) in exon 8, 1 patient (5.6%) was homozygous for a new splice-site mutation at the junction exon-intron 16 [c.1579_1580+4delAGGTAAinsTCAT] and no DPY19L2, SPATA16 or PICK1 mutations were identified for 4 patients (22.2%). By defining 15 specific LCR markers, we characterized 2 BPs for the DPY19L2 deletion in 11 patients showing the homozygous deletion. Using 20 non-LCR-specific SNPs, we identified 8 distinct haplotypes.

LIMITATIONS, REASONS FOR CAUTION

A limitation of this study is the small number of patients owing to the rarity of this form of male infertility.

WIDER IMPLICATIONS OF THE FINDINGS

Our data showed that some nucleotides, described by others as LCR-specific markers and used to limit their BPs, were in fact SNPs demonstrating the difficulty in precisely determining the localization of BPs.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by the French Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM), the Ministère de l'Education Nationale et de l'Enseignement Supérieur et de la Recherche, the University of Strasbourg, the University Hospital of Strasbourg, the Agence Nationale pour la Recherche, the Agence de la BioMédecine and l'Agence Universitaire de la Francophonie (AUF). There are no conflicts of interest to declare.

Ultrastructural Morphology of Sperm from Human Globozoospermia

Globozoospermia is a rare disorder characterized by the presence of sperm with round head, lacking acrosome. Coiling tail around the nucleus has been reported since early human studies, but no specific significance has conferred it. By contrast, studies on animal models suggest that coiling tail around the nucleus could represent a crucial step of defective spermatogenesis, resulting in round-headed sperm. No observations, so far, support the transfer of this hypothesis to human globozoospermia. The purpose of this work was to compare ultrastructural morphology of human and mouse model globozoospermic sperm. Sperm have been investigated by using scanning and transmission electron microscopy. The images that we obtained show significant similarities to those described in GOPC knockout mice, an animal model of globozoospermia. By using this model as reference, we were able to identify the probable steps of the tail coiling process in human globozoospermia. Although we have no evidence that there is the same pathophysiology in man and knocked-out mouse, the similarities between these ultrastructural observations in human and those in the experimental model are very suggestive. This is the first demonstration of the existence of relevant morphological homologies between the tail coiling in animal model and human globozoospermia.

Teratozoospermia: spotlight on the main genetic actors in the human

BACKGROUND

Male infertility affects >20 million men worldwide and represents a major health concern. Although multifactorial, male infertility has a strong genetic basis which has so far not been extensively studied. Recent studies of consanguineous families and of small cohorts of phenotypically homogeneous patients have however allowed the identification of a number of autosomal recessive causes of teratozoospermia. Homozygous mutations of aurora kinase C (AURKC) were first described to be responsible for most cases of macrozoospermia. Other genes defects have later been identified in spermatogenesis associated 16 (SPATA16) and dpy-19-like 2 (DPY19L2) in patients with globozoospermia and more recently in dynein, axonemal, heavy chain 1 (DNAH1) in a heterogeneous group of patients presenting with flagellar abnormalities previously described as dysplasia of the fibrous sheath or short/stump tail syndromes, which we propose to call multiple morphological abnormalities of the flagella (MMAF).

METHODS

A comprehensive review of the scientific literature available in PubMed/Medline was conducted for studies on human genetics, experimental models and physiopathology related to teratozoospermia in particular globozoospermia, large headed spermatozoa and flagellar abnormalities. The search included all articles with an English abstract available online before September 2014.

RESULTS

Molecular studies of numerous unrelated patients with globozoospermia and large-headed spermatozoa confirmed that mutations in DPY19L2 and AURKC are mainly responsible for their respective pathological phenotype. In globozoospermia, the deletion of the totality of the DPY19L2 gene represents ∼ 81% of the pathological alleles but point mutations affecting the protein function have also been described. In macrozoospermia only two recurrent mutations were identified in AURKC, accounting for almost all the pathological alleles, raising the possibility of a putative positive selection of heterozygous individuals. The recent identification of DNAH1 mutations in a proportion of patients with MMAF is promising but emphasizes that this phenotype is genetically heterogeneous. Moreover, the identification of mutations in a dynein strengthens the emerging point of view that MMAF may be a phenotypic variation of the classical forms of primary ciliary dyskinesia. Based on data from human and animal models, the MMAF phenotype seems to be favored by defects directly or indirectly affecting the central pair of axonemal microtubules of the sperm flagella.

CONCLUSIONS

The studies described here provide valuable information regarding the genetic and molecular defects causing infertility, to improve our understanding of the physiopathology of teratozoospermia while giving a detailed characterization of specific features of spermatogenesis. Furthermore, these findings have a significant influence on the diagnostic strategy for teratozoospermic patients allowing the clinician to provide the patient with informed genetic counseling, to adopt the best course of treatment and to develop personalized medicine directly targeting the defective gene products.

Dynamics of Sun5 localization during spermatogenesis in wild type and Dpy19l2 knock-out mice indicates that Sun5 is not involved in acrosome attachment to the nuclear envelope

The acrosome is an organelle that is central to sperm physiology and a defective acrosome biogenesis leads to globozoospermia, a severe male infertility. The identification of the actors involved in acrosome biogenesis is therefore particularly important to decipher the molecular pathogeny of globozoospermia. We recently showed that a defect in the DPY19L2 gene is present in more than 70% of globozoospermic men and demonstrated that Dpy19l2, located in the inner nuclear membrane, is the first protein involved in the attachment of the acrosome to the nuclear envelope (NE). SUN proteins serve to link the nuclear envelope to the cytoskeleton and are therefore good candidates to participate in acrosome-nucleus attachment, potentially by interacting with DPY19L2. In order to characterize new actors of acrosomal attachment, we focused on Sun5 (also called Spag4l), which is highly expressed in male germ cells, and investigated its localization during spermatogenesis. Using immunohistochemistry and Western blot experiments in mice, we showed that Sun5 transits through different cellular compartments during meiosis. In pachytene spermatocytes, it is located in a membranous compartment different to the reticulum. In round spermatids, it progresses to the Golgi and the NE before to be located to the tail/head junction in epididymal sperm. Interestingly, we demonstrate that Sun5 is not, as initially reported, facing the acrosome but is in fact excluded from this zone. Moreover, we show that in Dpy19l2 KO spermatids, upon the detachment of the acrosome, Sun5 relocalizes to the totality of the NE suggesting that the acrosome attachment excludes Sun5 from the NE facing the acrosome. Finally, Western-blot experiments demonstrate that Sun5 is glycosylated. Overall, our work, associated with other publications, strongly suggests that the attachment of the acrosome to the nucleus does not likely depend on the formation of SUN complexes.

Nuclear envelope remodelling during human spermiogenesis involves somatic B-type lamins and a spermatid-specific B3 lamin isoform

The nuclear lamina (NL) is a filamentous protein meshwork, composed essentially of lamins, situated between the inner nuclear membrane and the chromatin. There is mounting evidence that the NL plays a role in spermatid differentiation during spermiogenesis. The mouse spermatid NL is composed of the ubiquitous lamin B1 and the spermatid-specific lamin B3, an N-terminally truncated isoform of lamin B2. However, nothing is known about the NL in human spermatids. We therefore investigated the expression pattern and localization of A-type lamins (A, C and C2) and B-type lamins (B1, B2 and B3) during human spermiogenesis. Here, we show that a lamin B3 transcript is present in human spermatids and that B-type lamins are the only lamins detectable in human spermatids. We determine that, as shown for their mouse counterparts, human lamin B3, but not lamin B2, induces strong nuclear deformation, when ectopically expressed in HeLa cells. Co-immunofluorescence revealed that, in human spermatids, B-type lamins are present at the nuclear periphery, except in the region covered by the acrosome, and that as the spermatid matures the B-type lamins recede towards the posterior pole. Only lamin B1 remains detectable on 33-47% of ejaculated spermatozoa. On spermatozoa selected for normal head density, however, this fell to <6%, suggesting that loss of the NL signal may be linked to complete sperm nucleus compaction. The similarities revealed between lamin expression during human and rodent spermiogenesis, strengthen evidence that the NL and lamin B3 have conserved functions during the intense remodelling of the mammalian spermatid nucleus.

Genetic aspects of monomorphic teratozoospermia: a review

Teratozoospermia is characterized by the presence of spermatozoa with abnormal morphology over 85 % in sperm. When all the spermatozoa display a unique abnormality, teratozoospermia is said to be monomorphic. Two forms of monomorphic teratozoospermia, representing less than 1 % of male infertility, are recognized: macrozoospermia (also called macrocephalic sperm head syndrome) and globozoospermia (also called round-headed sperm syndrome). Macrozoospermia is defined as the presence of a very high percentage of spermatozoa with enlarged head and multiple flagella. Meiotic segregation studies in 30 males revealed that over 90 % of spermatozoa were aneuploid, mainly diploid. Sperm DNA fragmentation studies performed in a few patients showed an increase in DNA fragmentation index compared to fertile men. Four mutations in the AURKC gene, a key player in meiosis and more particularly in spermatogenesis, have been found to be responsible for macrozoospermia. Globozoospermia is characterized by round-headed spermatozoa with an absent acrosome, an aberrant nuclear membrane and midpiece defects. The rate of aneuploidy of various chromosomes in spermatozoa from 26 globozoospermic men was slightly increased compared to fertile men. However, this increase was of the same order as that commonly found in infertile men with altered sperm parameters. The majority of the studies found that globozoospermic males had a sperm DNA fragmentation index higher than in fertile men. Mutations or deletions in three genes, SPATA16, PICK1 and DPY19L2, have been shown to be responsible for globozoospermia. Identification of the genetic causes of macrozoospermia and globozoospermia should help refine diagnosis and treatment of these patients, avoiding long and painful treatments. Elucidating the molecular causes of these defects is of utmost importance as intracytoplasmic sperm injection (ICSI) is very disappointing in these two pathologies.

ICA1L forms BAR-domain complexes with PICK1 and is critical for acrosome formation in spermiogenesis

Mutations of the Pick1 gene cause globozoospermia, a male infertility disorder in both mice and human. PICK1 is critical for vesicle trafficking and its deficiency in sperm cells leads to abnormal vesicle trafficking from the Golgi to acrosome. This eventually disrupts acrosome formation and leads to male infertility. We identified a novel BAR-domain binding partner of PICK1: ICA1L, which has sequence similarities to ICA69. ICA1L is expressed in testes and brain, and is the major binding partner for PICK1 in testes. ICA1L and PICK1 are highly expressed in spermatids and trafficked together at different stages of spermiogenesis. ICA1L knockout mice were generated by CRISPR-Cas technology. PICK1 expression was reduced by 80% in the testes of male mice lacking ICA1L. Sperms from ICA1L knockout mice had abnormalities in acrosome, nucleus and mitochondrial sheath formation. Both total and mobile sperms were reduced in number and about half of the remaining sperms had characteristics of globozoospermia. These defects ultimately resulted in reduced fertility of male ICA1L knockout mice and the fertility of male mice was completely eliminated in ICA69/ICA1L double knockout mice.

Subcellular localization of phospholipase Cζ in human sperm and its absence in DPY19L2-deficient sperm are consistent with its role in oocyte activation

We recently identified the DPY19L2 gene as the main genetic cause of human globozoospermia (70%) and described that Dpy19l2 knockout (KO) mice faithfully reproduce the human phenotype of globozoospermia making it an excellent model to characterize the molecular physiopathology of globozoospermia. Recent case studies on non-genetically characterized men with globozoospermia showed that phospholipase C, zeta (PLCζ), the sperm factor thought to induce the Ca(2+) oscillations at fertilization, was absent from their sperm, explaining the poor fertilization potential of these spermatozoa. Since 30% of globozoospermic men remain genetically uncharacterized, the absence of PLCζ in DPY19L2 globozoospermic men remains to be formally established. Moreover, the precise localization of PLCζ and the reasons underlying its loss during spermatogenesis in globozoospermic patients are still not understood. Herein, we show that PLCζ is absent, or its presence highly reduced, in human and mouse sperm with DPY19L2-associated globozoospermia. As a consequence, fertilization with sperm from Dpy19l2 KO mice failed to initiate Ca(2+) oscillations and injected oocytes remained arrested at the metaphase II stage, although a few human oocytes injected with DPY19L2-defective sperm showed formation of 2-pronuclei embryos. We report for the first time the subcellular localization of PLCζ in control human sperm, which is along the inner acrosomal membrane and in the perinuclear theca, in the area corresponding to the equatorial region. Because these cellular components are absent in globozoospermic sperm, the loss of PLCζ in globozoospermic sperm is thus consistent and reinforces the role of PLCζ as an oocyte activation factor necessary for oocyte activation. In our companion article, we showed that chromatin compaction during spermiogenesis in Dpy19l2 KO mouse is defective and leads to sperm DNA damage. Together, these defects explain the poor fertilization potential of DPY19L2-globozoospermic sperm and the compromised developmental potential of embryos obtained using sperm from patients with a deletion of the DPY19L2 gene.

Dpy19l2-deficient globozoospermic sperm display altered genome packaging and DNA damage that compromises the initiation of embryo development

We recently identified the DPY19L2 gene as the main genetic cause of human globozoospermia. Non-genetically characterized cases of globozoospermia were associated with DNA alterations, suggesting that DPY19L2-dependent globozoospermia may be associated with poor DNA quality. However the origins of such defects have not yet been characterized and the consequences on the quality of embryos generated with globozoospermic sperm remain to be determined. Using the mouse model lacking Dpy19l2, we compared several key steps of nuclear compaction. We show that the kinetics of appearance and disappearance of the histone H4 acetylation waves and of transition proteins are defective. More importantly, the nuclear invasion by protamines does not occur. As a consequence, we showed that globozoospermic sperm presented with poor sperm chromatin compaction and sperm DNA integrity breakdown. We next assessed the developmental consequences of using such faulty sperm by performing ICSI. We showed in the companion article that oocyte activation (OA) with globozoospermic sperm is very poor and due to the absence of phospholipase Cζ; therefore artificial OA (AOA) was used to bypass defective OA. Herein, we evaluated the developmental potential of embryos generated by ICSI + AOA in mice. We demonstrate that although OA was fully rescued, preimplantation development was impaired when using globozoospermic sperm. In human, a small number of embryos could be generated with sperm from DPY19L2-deleted patients in the absence of AOA and these embryos also showed a poor developmental potential. In conclusion, we show that chromatin compaction during spermiogenesis in Dpy19l2 KO mouse is defective and leads to sperm DNA damage. Most of the DNA breaks were already present when the sperm reached the epididymis, indicating that they occurred inside the testis. This result thus suggests that testicular sperm extraction in Dpy19l2-dependent globozoospermia is not recommended. These defects may largely explain the poor embryonic development of most mouse and human embryos obtained with globozoospermic sperm.

Protein phospholipase C Zeta1 expression in patients with failed ICSI but with normal sperm parameters

PURPOSE

This study was conducted to determine if expression of the testis-specific phospholipase C Zeta1 (PLCZ1) correlated with low success or fertilization failure after ICSI in patients with normal parameters after standard semen analysis (SA).

METHODS

Couples <43 years with one or two failed or low fertilization ICSI cycles. Standard Semen Analysis (SA) was performed to determine sperm parameters in male partners, whereas females were evaluated for antral follicle counts (AFC), day 3 FSH levels and peak Estradiol (E2) levels. The presence of PLCZ1 in sperm was ascertained using Western blotting and Immunofluorescence (IF) analysis. The ability of sperm to initiate changes in the intracellular concentrations of free calcium ([Ca(2+)]i), which is characteristic of mammalian sperm, was performed after injection of human sperm into mouse eggs loaded with the Ca(2+) sensitive dye fura-2 AM.

RESULTS

Male partners of couples with failed or low success ICSI fertilization but with normal SA parameters showed low expression levels of PLCZ1 as determined by western blotting and reduced fluorescent signal during IF studies. In addition, fewer of these males' sperm showed PLCZ1 expression and were able to initiate robust [Ca(2+)]i oscillations upon injection into eggs.

CONCLUSION

Our data suggest that in patients with normal SA parameters but with repeated low fertilization or outright failed fertilization results after ICSI, abnormal PLCZ1 function should be considered as the underlying mechanism responsible for the failure of fertilization.

Comparative testicular transcriptome of wild type and globozoospermic Dpy19l2 knock out mice

BACKGROUND

Globozoospermia is a male infertility phenotype characterized by the presence in the ejaculate of near 100% acrosomeless round-headed spermatozoa with normal chromosomal content. Following intracytoplasmic sperm injection (ICSI) these spermatozoa give a poor fertilization rate and embryonic development. We showed previously that most patients have a 200 kb homozygous deletion, which includes DPY19L2 whole coding sequence. Furthermore we showed that the DPY19L2 protein is located in the inner nuclear membrane of spermatids during spermiogenesis and that it is necessary to anchor the acrosome to the nucleus thus performing a function similar to that realized by Sun proteins within the LINC-complex (Linker of Nucleoskeleton and Cytoskeleton). SUN1 was described to be necessary for gametogenesis and was shown to interact with the telomeres. It is therefore possible that Dpy19l2 could also interact, directly or indirectly, with the DNA and modulate gene expression during spermatogenesis. In this study, we compared the transcriptome of testes from Dpy19l2 knock out and wild type mice in order to identify a potential deregulation of transcripts that could explain the poor fertilization potential of Dpy19l2 mutated spermatozoa.

METHODS

RNA was extracted from testes from DPY19L2 knock out and wild type mice. The transcriptome was carried out using GeneChip® Mouse Exon 1.0 ST Arrays. The biological processes and molecular functions of the differentially regulated genes were analyzed with the PANTHER software.

RESULTS

A total of 76 genes were deregulated, 70 were up-regulated and 6 (including Dpy19l2) were down-regulated. These genes were found to be involved in DNA/RNA binding, structural organization, transport and catalytic activity.

CONCLUSIONS

We describe that an important number of genes are differentially expressed in Dpy19l2 mice. This work could help improving our understanding of Dpy19l2 functions and lead to a better comprehension of the molecular mechanism involved in spermatogenesis.

C. elegans DPY-19 is a C-mannosyltransferase glycosylating thrombospondin repeats

Among the different types of protein glycosylation, C-mannosylation of tryptophan residues stands out because of the unique linkage formed between sugar and protein. Instead of the typical O- or N-glycosidic linkage, a C-C bond is used for attachment of a single mannose. C-mannose is characteristically found in thrombospondin type 1 repeats and in the WSXWS motif of type I cytokine receptors. The genetic base of the enzymatic activity catalyzing C-mannosylation was not known. Here we demonstrate that Caenorhabditis elegans DPY-19 is a C-mannosyltransferase. DPY-19 exhibits topological and sequential homology to the N-glycan oligosaccharyltransferase, highlighting an evolutionary link between N- and C-glycosylation. We show that the C. elegans surface receptors MIG-21 and UNC-5 are acceptor substrates of DPY-19 and that C-mannosylation is essential for the secretion of soluble MIG-21. Thereby, our data provide an explanation for the previously described identical Q neuroblast migration phenotypes of dpy-19 and mig-21 mutants.

Fine characterisation of a recombination hotspot at the DPY19L2 locus and resolution of the paradoxical excess of duplications over deletions in the general population

We demonstrated previously that 75% of infertile men with round, acrosomeless spermatozoa (globozoospermia) had a homozygous 200-Kb deletion removing the totality of DPY19L2. We showed that this deletion occurred by Non-Allelic Homologous Recombination (NAHR) between two homologous 28-Kb Low Copy Repeats (LCRs) located on each side of the gene. The accepted NAHR model predicts that inter-chromatid and inter-chromosome NAHR create a deleted and a duplicated recombined allele, while intra-chromatid events only generate deletions. Therefore more deletions are expected to be produced de novo. Surprisingly, array CGH data show that, in the general population, DPY19L2 duplicated alleles are approximately three times as frequent as deleted alleles. In order to shed light on this paradox, we developed a sperm-based assay to measure the de novo rates of deletions and duplications at this locus. As predicted by the NAHR model, we identified an excess of de novo deletions over duplications. We calculated that the excess of de novo deletion was compensated by evolutionary loss, whereas duplications, not subjected to selection, increased gradually. Purifying selection against sterile, homozygous deleted men may be sufficient for this compensation, but heterozygously deleted men might also suffer a small fitness penalty. The recombined alleles were sequenced to pinpoint the localisation of the breakpoints. We analysed a total of 15 homozygous deleted patients and 17 heterozygous individuals carrying either a deletion (n = 4) or a duplication (n = 13). All but two alleles fell within a 1.2-Kb region central to the 28-Kb LCR, indicating that >90% of the NAHR took place in that region. We showed that a PRDM9 13-mer recognition sequence is located right in the centre of that region. Our results therefore strengthen the link between this consensus sequence and the occurrence of NAHR.

We demonstrated previously that most men with globozoospermia, who produce only round acrosomeless spermatozoa and are 100% infertile, had a homozygous deletion removing the totality of DPY19L2. We also showed that this deletion occurred by Non-Allelic Homologous Recombination (NAHR). NAHR results in the production of deletions and duplications of regions encompassed by two homologous sequences, normally with a higher occurrence of deletions over duplications. Analysis of public databases at the DPY19L2 locus paradoxically revealed that, in the general population, duplications were approximately three times as frequent as deletions. Analysis of sperm DNA permits us to quantify de novo events that take place during male meiosis. We therefore measured the rates of de novo deletion and duplication in the sperm of three healthy donors. As predicted by the NAHR theoretical model and contrary to the allelic frequency observed in the general population, we identified an approximate 2-fold excess of deletions over duplications. We calculated that the measured rate of de novo deletion was compensated by evolutionary loss, whereas duplications, not subjected to selection, increased gradually. Purifying selection against infertile homozygous deleted men may be sufficient for this compensation, or heterozygously deleted men may also suffer a small fitness penalty.