Deleterious genetic changes in AGTPBP1 result in teratozoospermia with sperm head and flagella defects

Approximately 10%-15% of couples worldwide are infertile, and male factors account for approximately half of these cases. Teratozoospermia is a major cause of male infertility. Although various mutations have been identified in teratozoospermia, these can vary among ethnic groups. In this study, we performed whole-exome sequencing to identify genetic changes potentially causative of teratozoospermia. Out of seven genes identified, one, ATP/GTP Binding Protein 1 (AGTPBP1), was characterized, and three missense changes were identified in two patients (Affected A: p.Glu423Asp and p.Pro631Leu; Affected B: p.Arg811His). In those two cases, severe sperm head and tail defects were observed. Moreover, AGTPBP1 localization showed a fragmented pattern compared to control participants, with specific localization in the neck and annulus regions. Using murine models, we found that AGTPBP1 is localized in the manchette structure, which is essential for sperm structure formation. Additionally, in Agtpbp1-null mice, we observed sperm head and tail defects similar to those in sperm from AGTPBP1-mutated cases, along with abnormal polyglutamylation tubulin and decreasing △-2 tubulin levels. In this study, we established a link between genetic changes in AGTPBP1 and human teratozoospermia for the first time and identified the role of AGTPBP1 in deglutamination, which is crucial for sperm formation.

Unveiling the Genetic Complexity of Teratozoospermia: Integrated Genomic Analysis Reveals Novel Insights into lncRNAs' Role in Male Infertility

Male infertility is a global health issue, affecting over 20 million men worldwide. Genetic factors are crucial in various male infertility forms, including teratozoospermia. Nonetheless, the genetic causes of male infertility remain largely unexplored. In this study, we employed whole-genome sequencing and RNA expression analysis to detect differentially expressed (DE) long-noncoding RNAs (lncRNAs) in teratozoospermia, along with mutations that are exclusive to teratozoospermic individuals within these DE lncRNAs regions. Bioinformatic tools were used to assess variants' impact on lncRNA structure, function, and lncRNA-miRNA interactions. Our analysis identified 1166 unique mutations in teratozoospermic men within DE lncRNAs, distinguishing them from normozoospermic men. Among these, 64 variants in 23 lncRNAs showed potential regulatory roles, 7 variants affected 4 lncRNA structures, while 37 variants in 17 lncRNAs caused miRNA target loss or gain. Pathway Enrichment and Gene Ontology analyses of the genes targeted by the affected miRNAs revealed dysregulated pathways in teratozoospermia and a link between male infertility and cancer. This study lists novel variants and lncRNAs associated for the first time with teratozoospermia. These findings pave the way for future studies aiming to enhance diagnosis and therapy in the field of male infertility.

Identification of nonfunctional SPATA20 causing acephalic spermatozoa syndrome in humans

Acephalic spermatozoa syndrome (ASS) is a rare and severe type of teratozoospermia characterized by the predominance of headless spermatozoa in the ejaculate. However, knowledge about the causative genes associated with ASS in humans is limited. Loss-of-function of SPATA20 has been suggested to result in the separation of the sperm head and flagellum in mice, whereas there have been no cases reporting SPATA20 variants leading to human male infertility. In this study, a nonsense mutation in SPATA20 (c.619C > T, p.Arg207*) was first identified in an ASS patient. Moreover, this variant contributed to the degradation of SPATA20 and was associated with decreased expression of SPATA6, which plays a vital role in the assembly of the sperm head-tail conjunction in humans. In addition, the infertility caused by loss-of-function mutation of SPATA20 might not be rescued by intracytoplasmic sperm injection (ICSI). Collectively, our findings suggested that SPATA20 might be required for sperm head-tail conjunction formation in humans, the nonfunction of which may lead to male infertility related to ASS. The discovery of the loss-of-function mutation in SPATA20 enriches the gene variant spectrum of human ASS, further contributing to improved diagnosis, genetic counseling and prognosis for male infertility.

[Intracytoplasmic sperm injection for patients with special types of teratozoospermia: Analysis of outcomes]

OBJECTIVE

To investigate the outcomes of intracytoplasmic sperm injection (ICSI) in the treatment of special types of teratozoospermia such as globozoospermia, acephalic spermatozoa syndrome (ASS) and multiple morphological abnormalities of sperm flagella (MMAF).

METHODS

We retrospectively analyzed the clinical data on 7 cases of globozoospermia (group A), 6 cases of ASS (group B) and 21 cases of MMAF (group C) treated by ICSI from January 2011 to January 2021, all confirmed with pathogenic or likely pathogenic gene variations. We compared the age, body mass index (BMI), sperm parameters, number of mature oocytes, and rates of fertilization, high-quality embryos, clinical pregnancy, live birth and spontaneous abortion among the three groups of patients.

RESULTS

There were no statistically significant differences in the age, BMI and number of metaphase Ⅱ (MⅡ) oocytes among the three groups (P > 0.05). Sperm concentration and motility were dramatically higher (P < 0.01) while the rates of fertilization, clinical pregnancy and live birth remarkably lower in group A than in B and C (P < 0.01). No statistically significant difference was observed in the spontaneous abortion rate among the three groups (P > 0.05).

CONCLUSION

ICSI can achieve relatively satisfactory outcomes of clinical pregnancy in patients with ASS or MMAF, but only a low fertilization rate or no fertilization at all in those with globozoospermia even if treated by artificial oocyte activation.

A loss-of-function variant in SSFA2 causes male infertility with globozoospermia and failed oocyte activation

Globozoospermia (OMIM: 102530) is a rare type of teratozoospermia (< 0.1%). The etiology of globozoospermia is complicated and has not been fully revealed. Here, we report an infertile patient with globozoospermia. Variational analysis revealed a homozygous missense variant in the SSFA2 gene (NM_001130445.3: c.3671G > A; p.R1224Q) in the patient. This variant significantly reduced the protein expression of SSFA2. Immunofluorescence staining showed positive SSFA2 expression in the acrosome of human sperm. Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) and Coimmunoprecipitation (Co-IP) analyses identified that GSTM3 and Actin interact with SSFA2. Further investigation revealed that for the patient, regular intracytoplasmic sperm injection (ICSI) treatment had a poor prognosis. However, Artificial oocyte activation (AOA) by a calcium ionophore (A23187) after ICSI successfully rescued the oocyte activation failure for the patient with the SSFA2 variant, and the couple achieved a live birth. This study revealed that SSFA2 plays an important role in acrosome formation, and the homozygous c.3671G > A loss-of-function variant in SSFA2 caused globozoospermia. SSFA2 may represent a new gene in the genetic diagnosis of globozoospermia, especially the successful outcome of AOA-ICSI treatment for couples, which has potential value for clinicians in their treatment regimen selections.

A novel homozygous mutation in DNAJB13-a gene associated with the sperm axoneme-leads to teratozoospermia

PURPOSE

To evaluate the unknown genetic causes of teratozoospermia, and determine the pathogenicity of candidate variants.

METHODS

A primary infertile patient and his family members were recruited in the West China Second University Hospital of Sichuan University. Whole-exome sequencing was performed to identify causative genes in a man with teratozoospermia. Immunofluorescence staining and western blotting were applied to assess the pathogenicity of the identified variant. Intracytoplasmic sperm injection (ICSI) was used to assist fertilization for the patient with teratozoospermia.

RESULTS

We performed whole-exome sequencing (WES) and detected a novel homozygous frameshift mutation of c.335_336del [p.E112Vfs*3] in DNAJB13 on a primary infertile male patient. Intriguingly, we identified abnormal sperm morphology in this patient, with recurrent respiratory infections and chronic cough. Furthermore, we confirmed that this mutation resulted in negative effects on DNAJB13 expression in the spermatozoa of the affected individual, causing ultrastructural defects in his sperm. Remarkably, our staining revealed that DNAJB13 was expressed in the cytoplasm of primary germ cells and in the flagella of spermatids during spermiogenesis in humans and mice. Finally, we are the first group to report a favorable prognosis using ICSI for a patient carrying this DNAJB13 mutation.

CONCLUSION

Our study revealed a novel homozygous frameshift mutation of c.335_336del [p.E112Vfs*3] in DNAJB13 involved in teratozoospermia phenotype. Our study greatly expands the spectrum of limited DNAJB13 mutations, and is expected to provide a better understanding of genetic counseling diagnoses and subsequent treatment of male infertility.

Homozygous SPAG6 variants can induce nonsyndromic asthenoteratozoospermia with severe MMAF

BACKGROUND

Multiple morphological abnormalities of the sperm flagella (MMAF) is a subtype of severe asthenoteratozoospermia with poorly understood genetic etiology. SPAG6 is a core axonemal component that plays a critical role in the formation of cilia and sperm flagella. Previous studies have reported that mutations in SPAG6 cause primary ciliary dyskinesia (PCD), but the association between SPAG6 gene variants and the MMAF phenotype has not yet been described.

METHODS

We performed whole-exome sequencing (WES) in two unrelated Han Chinese men with MMAF. Sanger sequencing was used to validate the candidate variants. Routine semen analysis was carried out according to the WHO guidelines (5^th Edition). Sperm morphology was assessed using modified Papanicolaou staining. Scanning and transmission electron microscopy (S/TEM) was performed to observe the ultrastructural defects of the sperm flagella. Western blot analysis and immunofluorescence (IF) of spermatozoa were performed to examine the expression of SPAG6 protein. Assisted fertilization with intracytoplasmic sperm injection (ICSI) was applied.

RESULTS

Two homozygous SPAG6 variants were identified by WES and Sanger validation in two patients with MMAF phenotype (F1 II-1: c.308C > A, p. A103D; F2 II-1: c. 585delA, p. K196Sfs*6). Semen analysis showed progressive rates of less than 1%, and most of the spermatozoa presented MMAF by Papanicolaou staining. TEM revealed that the overall axonemal ultrastructure was disrupted and primarily presented an abnormal "9 + 0" configuration. No other PCD-related symptoms were found on physical examination and medical consultations, as well as lung CT screening. The level of SPAG6 protein was significantly decreased in the spermatozoa, and IF analysis revealed that SPAG6 staining was extremely weak and discontinuous in the sperm flagella of the two patients. Notably, F1 II-1 and his wife conceived successfully after undergoing ICSI.

CONCLUSIONS

Our research provides new evidence for a potential correlation between SPAG6 variants and the MMAF phenotype.

Whole-genome methylation analysis of testicular germ cells from cryptozoospermic men points to recurrent and functionally relevant DNA methylation changes

BACKGROUND

Several studies have reported an association between male infertility and aberrant sperm DNA methylation patterns, in particular in imprinted genes. In a recent investigation based on whole methylome and deep bisulfite sequencing, we have not found any evidence for such an association, but have demonstrated that somatic DNA contamination and genetic variation confound methylation studies in sperm of severely oligozoospermic men. To find out whether testicular germ cells (TGCs) of such patients might carry aberrant DNA methylation, we compared the TGC methylomes of four men with cryptozoospermia (CZ) and four men with obstructive azoospermia, who had normal spermatogenesis and served as controls (CTR).

RESULTS

There was no difference in DNA methylation at the whole genome level or at imprinted regions between CZ and CTR samples. However, using stringent filters to identify group-specific methylation differences, we detected 271 differentially methylated regions (DMRs), 238 of which were hypermethylated in CZ (binominal test, p < 2.2 × 10-16). The DMRs were enriched for distal regulatory elements (p = 1.0 × 10-6) and associated with 132 genes, 61 of which are differentially expressed at various stages of spermatogenesis. Almost all of the 67 DMRs associated with the 61 genes (94%) are hypermethylated in CZ (63/67, p = 1.107 × 10-14). As judged by single-cell RNA sequencing, 13 DMR-associated genes, which are mainly expressed during meiosis and spermiogenesis, show a significantly different pattern of expression in CZ patients. In four of these genes, the promoter is hypermethylated in CZ men, which correlates with a lower expression level in these patients. In the other nine genes, eight of which downregulated in CZ, germ cell-specific enhancers may be affected.

CONCLUSIONS

We found that impaired spermatogenesis is associated with DNA methylation changes in testicular germ cells at functionally relevant regions of the genome. We hypothesize that the described DNA methylation changes may reflect or contribute to premature abortion of spermatogenesis and therefore not appear in the mature, motile sperm.

Pathogenesis of acephalic spermatozoa syndrome caused by splicing mutation and de novo deletion in TSGA10

PURPOSE

To identify the genetic causes for acephalic spermatozoa syndrome.

METHODS

Whole-exome sequencing was performed on the proband from a non-consanguineous to identify pathogenic mutations for acephalic spermatozoa syndrome. Quantitative real-time polymerase chain reaction and whole genome sequencing were subjected to detect deletion. The functional effect of the identified splicing mutation was investigated by minigene assay. Western blot and immunofluorescence were performed to detect the expression level and localization of mutant TSGA10 protein.

RESULTS

Here, we identified a novel heterozygous splicing mutation in TSGA10 (NM_025244: c.1108-1G > T), while we confirmed that there was a de novo large deletion in the proband. The splicing mutation led to the skipping of the exon15 of TSGA10, which resulted in a truncated protein (p. A370Efs*293). Therefore, we speculated that the splicing mutation might affect transcription and translation without the dosage compensation of a normal allele, which possesses a large deletion including intact TSGA10. Western blot and immunofluorescence demonstrated that the very low expression level of truncated TSGA10 protein led the proband to present the acephalic spermatozoa phenotype.

CONCLUSION

Our finding expands the spectrum of pathogenic TSGA10 mutations that are responsible for ASS and male infertility. It is also important to remind us of paying attention to the compound heterozygous deletion in patients from non-consanguineous families, so that we can provide more precise genetic counseling for patients.

The missing linker between SUN5 and PMFBP1 in sperm head-tail coupling apparatus

The sperm head-to-tail coupling apparatus (HTCA) ensures sperm head-tail integrity while defective HTCA causes acephalic spermatozoa, rendering males infertile. Here, we show that CENTLEIN is indispensable for HTCA integrity and function, and that inactivation of CENTLEIN in mice leads to sperm decapitation and male sterility. We demonstrate that CENTLEIN directly interacts with both SUN5 and PMFBP1, two proteins localized in the HTCA and related with acephalic spermatozoa syndrome. We find that the absence of Centlein sets SUN5 and PMFBP1 apart, the former close to the sperm head and the latter in the decapitated tail. We show that lack of Sun5 results in CENTLEIN and PMFBP1 left in the decapitated tail, while disruption of Pmfbp1 results in SUN5 and CENTLEIN left on the detached sperm head. These results demonstrate that CENTLEIN cooperating with SUN5 and PMFBP1 participates in the HTCA assembly and integration of sperm head to the tail, indicating that impairments of CENTLEIN might be associated with acephalic spermatozoa syndrome in humans.

Identification and Characterization of the Most Common Genetic Variant Responsible for Acephalic Spermatozoa Syndrome in Men Originating from North Africa

Acephalic spermatozoa syndrome (ASS) is a rare but extremely severe type of teratozoospermia, defined by the presence of a majority of headless flagella and a minority of tail-less sperm heads in the ejaculate. Like the other severe monomorphic teratozoospermias, ASS has a strong genetic basis and is most often caused by bi-allelic variants in SUN5 (Sad1 and UNC84 domain-containing 5). Using whole exome sequencing (WES), we investigated a cohort of nine infertile subjects displaying ASS. These subjects were recruited in three centers located in France and Tunisia, but all originated from North Africa. Sperm from subjects carrying candidate genetic variants were subjected to immunofluorescence analysis and transmission electron microscopy. Moreover, fluorescent in situ hybridization (FISH) was performed on sperm nuclei to assess their chromosomal content. Variant filtering permitted us to identify the same SUN5 homozygous frameshift variant (c.211+1_211+2dup) in 7/9 individuals (78%). SUN5 encodes a protein localized on the posterior part of the nuclear envelope that is necessary for the attachment of the tail to the sperm head. Immunofluorescence assays performed on sperm cells from three mutated subjects revealed a total absence of SUN5, thus demonstrating the deleterious impact of the identified variant on protein expression. Transmission electron microscopy showed a conserved flagellar structure and a slightly decondensed chromatin. FISH did not highlight a higher rate of chromosome aneuploidy in spermatozoa from SUN5 patients compared to controls, indicating that intra-cytoplasmic sperm injection (ICSI) can be proposed for patients carrying the c.211+1_211+2dup variant. These results suggest that the identified SUN5 variant is the main cause of ASS in the North African population. Consequently, a simple and inexpensive genotyping of the 211+1_211+2dup variant could be beneficial for affected men of North African origin before resorting to more exhaustive genetic analyses.

Novel Loss-of-Function Mutations in DNAH1 Displayed Different Phenotypic Spectrum in Humans and Mice

Male infertility is a prevalent disorder distressing an estimated 70 million people worldwide. Despite continued progress in understanding the causes of male infertility, idiopathic sperm abnormalities such as multiple morphological abnormalities of sperm flagella (MMAF) still account for about 30% of male infertility. Recurrent mutations in DNAH1 have been reported to cause MMAF in various populations, but the underlying mechanism is still poorly explored. This study investigated the MMAF phenotype of two extended consanguineous Pakistani families without manifesting primary ciliary dyskinesia symptoms. The transmission electron microscopy analysis of cross-sections of microtubule doublets revealed a missing central singlet of microtubules and a disorganized fibrous sheath. SPAG6 staining, a marker generally used to check the integration of microtubules of central pair, further confirmed the disruption of central pair in the spermatozoa of patients. Thus, whole-exome sequencing (WES) was performed, and WES analysis identified two novel mutations in the DNAH1 gene that were recessively co-segregating with MMAF phenotype in both families. To mechanistically study the impact of identified mutation, we generated Dnah1 mice models to confirm the in vivo effects of identified mutations. Though Dnah1^{△iso1/△iso1} mutant mice represented MMAF phenotype, no significant defects were observed in the ultrastructure of mutant mice spermatozoa. Interestingly, we found DNAH1 isoform2 in Dnah1^{△iso1/△iso1} mutant mice that may be mediating the formation of normal ultrastructure in the absence of full-length protein. Altogether we are first reporting the possible explanation of inconsistency between mouse and human DNAH1 mutant phenotypes, which will pave the way for further understanding of the underlying pathophysiological mechanism of MMAF.

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.

Identification of a New QTL Region on Mouse Chromosome 1 Responsible for Male Hypofertility: Phenotype Characterization and Candidate Genes

Male fertility disorders often have their origin in disturbed spermatogenesis, which can be induced by genetic factors. In this study, we used interspecific recombinant congenic mouse strains (IRCS) to identify genes responsible for male infertility. Using ultrasonography, in vivo and in vitro fertilization (IVF) and electron microscopy, the phenotyping of several IRCS carrying mouse chromosome 1 segments of Mus spretus origin revealed a decrease in the ability of sperm to fertilize. This teratozoospermia included the abnormal anchoring of the acrosome to the nucleus and a persistence of residual bodies at the level of epididymal sperm midpiece. We identified a quantitative trait locus (QTL) responsible for these phenotypes and we have proposed a short list of candidate genes specifically expressed in spermatids. The future functional validation of candidate genes should allow the identification of new genes and mechanisms involved in male infertility.

[Detection of DPY19L2 gene mutation in 2 cases of globozoospermia]

OBJECTIVE

To investigate the mutation of the DPY19L2 gene in patients with globozoospermia.

METHODS

We collected the clinical data and peripheral blood from 2 patients with globozoospermia and screened for mutation of the DPY19L2 gene by PCR amplification and DNA sequencing technology.

RESULTS

The sperm from the 2 globozoospermia patients were round morphologically under the light microscope, with deeply stained nuclei but no acrosome. Electron microscopy showed the sperm with a large round head but no acrosomal structure, the nuclei enveloped by a single layer of membrane and the cytoplasm dispersed. PCR amplification revealed homozygous deletion of Exon 5, Exon6 and Exon15 in the DPY19L2 gene in both the patients.

CONCLUSIONS

This study proved that the homozygous mutation of DPY19L2 could lead to globozoospermia, which has an important significance for researches on the molecular mechanisms and gene diagnosis of the disease as well as for clinicians in genetic counseling and treatment.

[Analysis of (DPY19L2 gene variant in two brothers affected with globozoospermia]

OBJECTIVE

To explore the molecular basis for two brothers affected with globozoospermia.

METHODS

Whole exome sequencing was carried out for both patients. Candidate variant was verified by Sanger sequencing and quantitative real-time PCR (qRT-PCR).

RESULTS

Whole exome sequencing, Sanger sequencing and qRT-PCR verification revealed a heterozygous c.384dup (p.Glu129*) variant in the DPY19L2 gene in the two brothers and their mother. A large heterozygous deletion, spanning approximately 164.5 kb and encompassing the entire DPY19L2 gene, was detected on chromosome 12 of the two patients and their father.

CONCLUSION

The c.384dup (p.Glu129*) variant and deletion of the DPY19L2 gene probably underlie the pathogenesis of globozoospermia in the two patients, which was in keeping with the autosomal recessive inheritance of disease in this pedigree.

[Advances in the molecular genetic studies of acephalic spermatozoa syndrome]

Acephalic spermatozoa syndrome (ASS) is characterized by a predominance of headless spermatozoa with abnormal head-tail junction in the ejaculate, which causes severe male infertility. The pathogenic mechanism of ASS remained unclarified for a long time until recent identification of the four ASS-associated genes SUN5, PMFBP1, TSGA10, and BRDT and their mutations due to the development of high-throughput sequencing technology. This review summarizes the advances in the genetic studies of ASS, focusing on its pathogenic molecular mechanisms, which provide an important basis for the molecular diagnosis of the disease as well as for assisted reproductive technology.

Whole-exome sequencing identified a novel mutation of AURKC in a Chinese family with macrozoospermia

PURPOSE

Macrozoospermia is a rare sperm morphologic abnormality associated with male infertility and is characterized by a high percentage of spermatozoa with large irregular heads. The aim of this study was to identify the genetic cause of an infertile male with macrozoospermia from a consanguineous family.

METHODS

Whole-exome sequencing (WES) was performed using peripheral blood genomic DNA from the patient and his parents.

RESULTS

WES analysis of the patient with macrozoospermia from a consanguineous family allowed the identification of a novel homozygous missense variant in the AURKC gene (c.269G>A). Bioinformatics analysis also suggested this variant a pathogenic mutation. Quantitative real-time PCR analysis showed that the mRNA level of AURKC is significantly decreased in the patient compared with his father. Moreover, no embryos were available for transfer after ICSI.

CONCLUSIONS

These results further support the important role of AURKC in male infertility and guide the practitioner in optimal decision making for patients with macrozoospermia.

[Advances in the studies of teratospermia-related genes]

Sperm morphology is one of the important indicators for the evaluation of male fertility. In recent years, there has been a gradual increase in the incidence of male infertility and that of infertility-associated teratospermia. Scholars at home and abroad are trying to explore the pathogenesis of teratospermia at the molecular level. With a review of recent studies on teratospermia, we present an overview of abnormal sperm morphology in the aspects of sperm head, neck and tail deformities, focusing on teratospermia-related genes, such as SPATA16, DPY19L2, PICK1, ZPBP1, SIRT1, AURKC, SPATA6, SUN5, ODF1, and DNAH1, aiming to provide a theoretical basis and some reference for the diagnosis and treatment of teratospermia.

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.

[Idiopathic teratozoospermia is not correlated with c.144delC polymorphism in the AURKC gene in Sichuan]

OBJECTIVE

To investigate the association of a very common mutation of c.144delC in the aurora kinase C (AURKC) gene with idiopathic teratozoospermia in Chinese infertile men in Sichuan.

METHODS

Using polymerase chain reaction (PCR) and next-generation sequencing, we analyzed the correlation between c.144delC polymorphism of the AURKC gene and male infertility in 98 idiopathic teratozoospermia patients in comparison with 162 normal fertile men.

RESULTS

Neither c.144delC mutation nor other meaningful mutations were detected in the AURKC gene in the 98 idiopathic teratozoospermia patients or the 162 normal controls.

CONCLUSIONS

Teratozoospermia is not correlated with c.144delC mutation in the AURKC gene in the men of the Sichuan area. Therefore, large-scale genotyping of the AURKC gene may not be necessary clinically among Chinese patients with idiopathic teratozoospermia.

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.

Detection of candidate nectin gene mutations in infertile men with severe teratospermia

PURPOSE

Approximately 40% of infertile men have an abnormal semen analysis, resulting from either abnormalities of sperm production (defective spermatogenesis) or sperm shape (defective spermiogenesis). This latter process is dependent upon the function of Sertoli cells, which maintain specialized junctional complexes with germ cells. Nectins, members of the immunoglobulin superfamily, participate in formation of these dynamic complexes. Male mice in which the nectin-2 or nectin-3 gene is knocked out are sterile. Their spermatozoa exhibit severe teratospermia, altered motility, and an impaired ability to fertilize eggs. We asked whether mutations in the protein coding regions of the nectin-2 (aka PVRL2) and nectin-3 (aka PVRL3) genes could be detected in men from infertile couples whose semen analysis revealed unimpaired sperm production, judged by normal sperm concentration, but severe abnormalities in sperm shape.

METHODS

Ejaculates were snap frozen in liquid nitrogen and later submitted for Sanger analysis of these two genes, to detect mutations in their protein coding regions.

RESULTS

Eighty-nine of 455 ejaculates (19.5%) met the inclusion criteria for study. Two of the 56 samples that were successfully analyzed for nectin-2 (3.6%) and one of 73 (1.3%) analyzed for nectin-3 possessed possibly damaging mutations.

CONCLUSIONS

Despite the small-scale nature of the study, at least two low-frequency deleterious variants were identified. These results suggest the need for a larger-scale study of sequence variants in the nectins in severe teratospermia.

Comparative expression profiling of testis-enriched genes regulated during the development of spermatogonial cells

The testis has been identified as the organ in which a large number of tissue-enriched genes are present. However, a large portion of transcripts related to each stage or cell type in the testis still remains unknown. In this study, databases combined with confirmatory measurements were used to investigate testis-enriched genes, localization in the testis, developmental regulation, gene expression profiles of testicular disease, and signaling pathways. Our comparative analysis of GEO DataSets showed that 24 genes are predominantly expressed in testis. Cellular locations of 15 testis-enriched proteins in human testis have been identified and most of them were located in spermatocytes and round spermatids. Real-time PCR revealed that expressions of these 15 genes are significantly increased during testis development. Also, an analysis of GEO DataSets indicated that expressions of these 15 genes were significantly decreased in teratozoospermic patients and polyubiquitin knockout mice, suggesting their involvement in normal testis development. Pathway analysis revealed that most of those 15 genes are implicated in various sperm-related cell processes and disease conditions. This approach provides effective strategies for discovering novel testis-enriched genes and their expression patterns, paving the way for future characterization of their functions regarding infertility and providing new biomarkers for specific stages of spematogenesis.

[Genetic genes associated with oligospermia, asthenospermia and teratospermia: Advances in studies]

Approximately 2,300 genes are found to be associated with spermiogenesis and their expressions play important roles in the regulation of spermiogenesis. In recent years, more and more attention has been focused on the studies of the genes associated with oligospermia, asthenospermia and teratospermia and their molecular mechanisms. Some genes, such as GSTM1, DNMT3L, and CYP1A1, have been shown to be potentially associated with oligospermia; some, such as CATSPER1, CRISP2, SEPT4, TCTE3, TEKT4, and DNAH1, with asthenospermia; and still others, such as DPY19L2 and AURKC, with teratospermia. These findings have provided a molecular basis for the studies of the pathogenesis of oligospermia, asthenospermia and teratospermia, as well as a new approach to the exploration of new diagnostic and therapeutic techniques.