Absence of CFAP69 Causes Male Infertility due to Multiple Morphological Abnormalities of the Flagella in Human and Mouse

A novel homozygous LRRC6 mutation causes male infertility with asthenozoospermia and primary ciliary dyskinesia in humans

BACKGROUND

Dysfunction of motile cilia, including respiratory cilia and sperm flagella, typically leads to primary ciliary dyskinesia and male infertility or low fertility in humans. Genetic defects of LRRC6 have been associated with primary ciliary dyskinesia and asthenozoospermia due to abnormal ultrastructure of ciliated axonemes.

OBJECTIVES

To identify novel mutations of the LRRC6 gene related to multiple morphological abnormalities of the sperm flagella and male infertility and investigate the underlying molecular mechanisms involved.

MATERIALS AND METHODS

The LRRC6 mutations were identified by whole exome sequencing and confirmed with Sanger sequencing. Papanicolaou staining, scanning, and transmission electron microscopy were performed to investigate the morphological and ultrastructural characteristics of spermatozoa. Further tandem mass tagging proteomics analyses were performed to explore the effect of mutations and confirmed by immunostaining and western blotting. Intracytoplasmic sperm injection was applied for the assisted reproductive therapy of males harboring biallelic LRRC6 mutations.

RESULTS

In this study, we identified a novel homozygous LRRC6 mutation in a consanguineous family, characterized by asthenozoospermia and primary ciliary dyskinesia. Further Semen parameter and morphology analysis demonstrate that the novel LRRC6 mutation leads to a significant reduction in sperm flagella length, a decrease in sperm progressive motility parameters, and abnormalities of sperm ultrastructure. Specifically, the absence of outer dynein arms and inner dynein arms, and incomplete mitochondrial sheath in the flagellar mid-piece were observed by transmission electron microscopy. In addition, tandem mass tagging proteomics analysis revealed that spermatozoa obtained from patients harboring the LRRC6 mutation exhibited a significant decrease in the expression levels of proteins related to the assembly and function of dynein axonemal arms. Functional analysis revealed that this novel LRRC6 mutation disrupted the function of the leucine-rich repeat containing 6 protein, which in turn affects the expression of the dynein arm proteins and leucine-rich repeat containing 6-interacting proteins CCDC40, SPAG1, and ZMYND10. Finally, we reported a successful pregnancy through assisted reproductive technology with intracytoplasmic sperm injection in the female partner of the proband.

DISCUSSION AND CONCLUSION

This study highlights the identification of a novel homozygous LRRC6 mutation in a consanguineous family and its impact on sperm progressive motility, morphology, and sperm kinetics parameters, which could facilitate the genetic diagnosis of asthenozoospermia and offer valuable perspectives for future genetic counseling endeavors.

The Role of Z Chromosome Localization Gene psmd9 in Spermatogenesis of Cynoglossus semilaevis

Proteasome 26S Subunit, Non-ATPase 9 (psmd9) plays an important role in the balance of protamine and the stability of the nucleolar structure during spermatogenesis. In this study, we cloned the psmd9 of Cynoglossus semilaevis and analyzed its expression pattern. psmd9 was identified on the Z chromosome of C. semilaevis, which is considered an interesting candidate gene for spermatogenesis. qRT-PCR and FISH experiments showed that the psmd9 gene was significantly highly expressed in the testes. It is worth noting that the expression level of psmd9 in male fish testes is significantly higher than that in pseudomales. In order to further explore the role of psmd9 in spermatogenesis, a male testicular cell line was used as the experimental material. The results of the psmd9-RNAi and overexpression experiments showed that psmd9 had a synergistic effect with spermatogenesis-related genes dnd1, cfap69, dnah3 and dnajb13, but had an antagonistic effect with ccne2. Our findings offer a scientific foundation for comprehending the role of psmd9 in the spermatogenesis regulatory network of C. semilaevis.

Conserved genes regulating human sex differentiation, gametogenesis and fertilization

The study of the functional genome in mice and humans has been instrumental for describing the conserved molecular mechanisms regulating human reproductive biology, and for defining the etiologies of monogenic fertility disorders. Infertility is a reproductive disorder that includes various conditions affecting a couple's ability to achieve a healthy pregnancy. Recent advances in next-generation sequencing and CRISPR/Cas-mediated genome editing technologies have facilitated the identification and characterization of genes and mechanisms that, if affected, lead to infertility. We report established genes that regulate conserved functions in fundamental reproductive processes (e.g., sex determination, gametogenesis, and fertilization). We only cover genes the deletion of which yields comparable fertility phenotypes in both rodents and humans. In the case of newly-discovered genes, we report the studies demonstrating shared cellular and fertility phenotypes resulting from loss-of-function mutations in both species. Finally, we introduce new model systems for the study of human reproductive biology and highlight the importance of studying human consanguineous populations to discover novel monogenic causes of infertility. The rapid and continuous screening and identification of putative genetic defects coupled with an efficient functional characterization in animal models can reveal novel mechanisms of gene function in human reproductive tissues.

Genetic Causes of Qualitative Sperm Defects: A Narrative Review of Clinical Evidence

Several genes are implicated in spermatogenesis and fertility regulation, and these genes are presently being analysed in clinical practice due to their involvement in male factor infertility (MFI). However, there are still few genetic analyses that are currently recommended for use in clinical practice. In this manuscript, we reviewed the genetic causes of qualitative sperm defects. We distinguished between alterations causing reduced sperm motility (asthenozoospermia) and alterations causing changes in the typical morphology of sperm (teratozoospermia). In detail, the genetic causes of reduced sperm motility may be found in the alteration of genes associated with sperm mitochondrial DNA, mitochondrial proteins, ion transport and channels, and flagellar proteins. On the other hand, the genetic causes of changes in typical sperm morphology are related to conditions with a strong genetic basis, such as macrozoospermia, globozoospermia, and acephalic spermatozoa syndrome. We tried to distinguish alterations approved for routine clinical application from those still unsupported by adequate clinical studies. The most important aspect of the study was related to the correct identification of subjects to be tested and the correct application of genetic tests based on clear clinical data. The correct application of available genetic tests in a scenario where reduced sperm motility and changes in sperm morphology have been observed enables the delivery of a defined diagnosis and plays an important role in clinical decision-making. Finally, clarifying the genetic causes of MFI might, in future, contribute to reducing the proportion of so-called idiopathic MFI, which might indeed be defined as a subtype of MFI whose cause has not yet been revealed.

Gene-knockout by iSTOP enables rapid reproductive disease modeling and phenotyping in germ cells of the founder generation

Cytosine base editing achieves C•G-to-T•A substitutions and can convert four codons (CAA/CAG/CGA/TGG) into STOP-codons (induction of STOP-codons, iSTOP) to knock out genes with reduced mosaicism. iSTOP enables direct phenotyping in founders' somatic cells, but it remains unknown whether this works in founders' germ cells so as to rapidly reveal novel genes for fertility. Here, we initially establish that iSTOP in mouse zygotes enables functional characterization of known genes in founders' germ cells: Cfap43-iSTOP male founders manifest expected sperm features resembling human "multiple morphological abnormalities of the flagella" syndrome (i.e., MMAF-like features), while oocytes of Zp3-iSTOP female founders have no zona pellucida. We further illustrate iSTOP's utility for dissecting the functions of unknown genes with Ccdc183, observing MMAF-like features and male infertility in Ccdc183-iSTOP founders, phenotypes concordant with those of Ccdc183-KO offspring. We ultimately establish that CCDC183 is essential for sperm morphogenesis through regulating the assembly of outer dynein arms and participating in the intra-flagellar transport. Our study demonstrates iSTOP as an efficient tool for direct reproductive disease modeling and phenotyping in germ cells of the founder generation, and rapidly reveals the essentiality of Ccdc183 in fertility, thus providing a time-saving approach for validating genetic defects (like nonsense mutations) for human infertility.

Lack of CCDC146, a ubiquitous centriole and microtubule-associated protein, leads to non-syndromic male infertility in human and mouse

From a cohort of 167 infertile patients suffering from multiple morphological abnormalities of the flagellum (MMAF), pathogenic bi-allelic mutations were identified in the CCDC146 gene. In somatic cells, CCDC146 is located at the centrosome and at multiple microtubule-related organelles during mitotic division, suggesting that it is a microtubule-associated protein (MAP). To decipher the molecular pathogenesis of infertility associated with CCDC146 mutations, a Ccdc146 knock-out (KO) mouse line was created. KO male mice were infertile, and sperm exhibited a phenotype identical to CCDC146 mutated patients. CCDC146 expression starts during late spermiogenesis. In the spermatozoon, the protein is conserved but is not localized to centrioles, unlike in somatic cells, rather it is present in the axoneme at the level of microtubule doublets. Expansion microscopy associated with the use of the detergent sarkosyl to solubilize microtubule doublets suggests that the protein may be a microtubule inner protein (MIP). At the subcellular level, the absence of CCDC146 impacted all microtubule-based organelles such as the manchette, the head-tail coupling apparatus (HTCA), and the axoneme. Through this study, a new genetic cause of infertility and a new factor in the formation and/or structure of the sperm axoneme were characterized.

Identification of CFAP52 as a novel diagnostic target of male infertility with defects of sperm head-tail connection and flagella development

Male infertility is a worldwide population health concern. Asthenoteratozoospermia is a common cause of male infertility, but its etiology remains incompletely understood. No evidence indicates the relevance of CFAP52 mutations to human male infertility. Our whole-exome sequencing identified compound heterozygous mutations in CFAP52 recessively cosegregating with male infertility status in a non-consanguineous Chinese family. Spermatozoa of CFAP52-mutant patient mainly exhibited abnormal head-tail connection and deformed flagella. Cfap52-knockout mice resembled the human infertile phenotype, showing a mixed acephalic spermatozoa syndrome (ASS) and multiple morphological abnormalities of the sperm flagella (MMAF) phenotype. The ultrastructural analyses further revealed a failure of connecting piece formation and a serious disorder of '9+2' axoneme structure. CFAP52 interacts with a head-tail coupling regulator SPATA6 and is essential for its stability. Expression of microtubule inner proteins and radial spoke proteins were reduced after the CFAP52 deficiency. Moreover, CFAP52-associated male infertility in humans and mice could be overcome by intracytoplasmic sperm injection (ICSI). The study reveals a prominent role for CFAP52 in sperm development, suggesting that CFAP52 might be a novel diagnostic target for male infertility with defects of sperm head-tail connection and flagella development.

CCDC146 is required for sperm flagellum biogenesis and male fertility in mice

Multiple morphological abnormalities of the flagella (MMAF) is a severe disease of male infertility, while the pathogenetic mechanisms of MMAF are still incompletely understood. Previously, we found that the deficiency of Ccdc38 might be associated with MMAF. To understand the underlying mechanism of this disease, we identified the potential partner of this protein and found that the coiled-coil domain containing 146 (CCDC146) can interact with CCDC38. It is predominantly expressed in the testes, and the knockout of this gene resulted in complete infertility in male mice but not in females. The knockout of Ccdc146 impaired spermiogenesis, mainly due to flagellum and manchette organization defects, finally led to MMAF-like phenotype. Furthermore, we demonstrated that CCDC146 could interact with both CCDC38 and CCDC42. It also interacts with intraflagellar transport (IFT) complexes IFT88 and IFT20. The knockout of this gene led to the decrease of ODF2, IFT88, and IFT20 protein levels, but did not affect CCDC38, CCDC42, or ODF1 expression. Additionally, we predicted and validated the detailed interactions between CCDC146 and CCDC38 or CCDC42, and built the interaction models at the atomic level. Our results suggest that the testis predominantly expressed gene Ccdc146 is essential for sperm flagellum biogenesis and male fertility, and its mutations might be associated with MMAF in some patients.

Assessing genetic diversity and defining signatures of positive selection on the genome of dromedary camels from the southeast of the Arabian Peninsula

Dromedary camels (Camelus dromedarius) are members of the Camelini tribe within the Camelidae family. They are distributed throughout North Africa, the Arabian Peninsula and Southeast Asia. This domestic species is characterized by its superior adaptability to the harsh desert environment. In this study, whole autosomal data of 29 dromedary samples from the Southeast Arabian Peninsula in Oman; 10 from Muscat, 14 from Al-Batinah, and 5 from Al-Sharqiya, were investigated to assess their genetic relationship and to define candidate signatures of positive selection. A minimal genetic distinction that separates Muscat dromedaries from the other two populations was observed, with a degree of genetic admixture between them. Using the de-correlated composite of multiple signals (DCMS) approach, a total of 47 candidate regions within the autosomes of these dromedary populations were defined with signatures of positive selection. These candidate regions harbor a total of 154 genes that are mainly associated with functional categories related to immune response, lipid metabolism and energy expenditure, optical and auditory functions, and long-term memory. Different functional genomic variants were called on the candidate regions and respective genes that warrant further investigation to find possible association with the different favorable phenotypes in dromedaries. The output of this study paves the way for further research efforts aimed at defining markers for use in genomic breeding programs, with the goal of conserving the genetic diversity of the species and enhancing its productivity.

The human sperm proteome-Toward a panel for male fertility testing

BACKGROUND

Although male factor accounts for 40%-50% of unintended childlessness, we are far from fully understanding the detailed causes. Usually, affected men cannot even be provided with a molecular diagnosis.

OBJECTIVES

We aimed at a higher resolution of the human sperm proteome for better understanding of the molecular causes of male infertility. We were particularly interested in why reduced sperm count decreases fertility despite many normal-looking spermatozoa and which proteins might be involved.

MATERIAL AND METHODS

Applying mass spectrometry analysis, we qualitatively and quantitatively examined the proteomic profiles of spermatozoa from 76 men differing in fertility. Infertile men had abnormal semen parameters and were involuntarily childless. Fertile subjects exhibited normozoospermia and had fathered children without medical assistance.

RESULTS

We discovered proteins from about 7000 coding genes in the human sperm proteome. These were mainly known for involvements in cellular motility, response to stimuli, adhesion, and reproduction. Numbers of sperm proteins showing at least threefold deviating abundances increased from oligozoospermia (N = 153) and oligoasthenozoospermia (N = 154) to oligoasthenoteratozoospermia (N = 368). Deregulated sperm proteins primarily engaged in flagellar assembly and sperm motility, fertilization, and male gametogenesis. Most of these participated in a larger network of male infertility genes and proteins.

DISCUSSION

We expose 31 sperm proteins displaying deviant abundances under infertility, which already were known before to have fertility relevance, including ACTL9, CCIN, CFAP47, CFAP65, CFAP251 (WDR66), DNAH1, and SPEM1. We propose 18 additional sperm proteins with at least eightfold differential abundance for further testing of their diagnostic potential, such as C2orf16, CYLC1, SPATA31E1, SPATA31D1, SPATA48, EFHB (CFAP21), and FAM161A.

CONCLUSION

Our results shed light on the molecular background of the dysfunctionality of the fewer spermatozoa produced in oligozoospermia and syndromes including it. The male infertility network presented may prove useful in further elucidating the molecular mechanism of male infertility.

A novel mutation in PCD-associated gene DNAAF3 causes male infertility due to asthenozoospermia

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive disease manifested with recurrent infections of respiratory tract and infertility. DNAAF3 is identified as a novel gene associated with PCD and different mutations in DNAAF3 results in different clinical features of PCD patients, such as situs inversus, sinusitis and bronchiectasis. However, the sperm phenotypic characteristics of PCD males are generally poorly investigated. Our reproductive medicine centre received a case of PCD patient with infertility, who presented with sinusitis, recurrent infections of the lower airway and severe asthenozoospermia; However, no situs inversus was found in the patient. A novel homozygous mutation in DNAAF3(c.551T>A; p.V184E) was identified in the PCD patient by whole-exome sequencing. Subsequent Sanger sequencing further confirmed that the DNAAF3 had a homozygous missense variant in the fifth exon. Transmission electron microscopy and immunostaining analysis of the sperms from the patient showed a complete absence of outer dynein arms and partial absence of inner dynein arms, which resulted in the reduction in sperm motility. However, this infertility was overcome by intracytoplasmic sperm injections, as his wife achieved successful pregnancy. These findings showed that the PCD-associated pathogenic mutation within DNAAF3 also causes severe asthenozoospermia and male infertility ultimately due to sperm flagella axoneme defect in humans. Our study not only contributes to understand the sperm phenotypic characteristics of patients with DNAAF3 mutations but also expands the spectrum of DNAAF3 mutations and may contribute to the genetic diagnosis and therapy for infertile patient with PCD.

A novel variant in CFAP69 causes asthenoteratozoospermia with treatable ART outcomes and a literature review

PURPOSE

Multiple morphological abnormalities of the sperm flagella (MMAF) are a severe form of sperm defect causing male infertility. Previous studies identified the variants in the CFAP69 gene as a MMAF-associated factor, but few cases have been reported. This study was performed to identify additional variants in CFAP69 and describe the semen characteristics and outcomes of assisted reproductive technology (ART) in CFAP69-affected couples.

METHODS

Genetic testing with next-generation sequencing (NGS) panel of 22 MMAF-associated genes and Sanger sequencing was performed in a cohort of 35 infertile males with MMAF to identify pathogenic variants. Morphological, ultrastructural, and immunostaining analyses were performed to investigate the characteristics of probands' spermatozoa. ART with intracytoplasmic sperm injection (ICSI) was carried out for the affected couples to get their own progenies.

RESULTS

We identified a novel frameshift variant in CFAP69 (c.2061dup, p. Pro688Thrfs*5) from a MMAF-affected infertile male with low sperm motility and malformed morphology of sperm. Furthermore, transmission electron microscopy and immunofluorescence staining revealed that the variant induced the aberrant ultrastructure and reduction of CFAP69 expression in the proband's spermatozoa. Moreover, the partner of the proband birthed a healthy girl through ICSI.

CONCLUSIONS

This study expanded the variant spectrum of CFAP69 and described the good outcome of ART treatment with ICSI, which is beneficial to the molecular diagnosis, genetic counseling, and treatment of infertile males with MMAF in the future.

Genetic data visualization using literature text-based neural networks: Examples associated with myocardial infarction

Data visualization is critical to unraveling hidden information from complex and high-dimensional data. Interpretable visualization methods are critical, especially in the biology and medical fields, however, there are limited effective visualization methods for large genetic data. Current visualization methods are limited to lower-dimensional data and their performance suffers if there is missing data. In this study, we propose a literature-based visualization method to reduce high-dimensional data without compromising the dynamics of the single nucleotide polymorphisms (SNP) and textual interpretability. Our method is innovative because it is shown to (1) preserves both global and local structures of SNP while reducing the dimension of the data using literature text representations, and (2) enables interpretable visualizations using textual information. For performance evaluations, we examined the proposed approach to classify various classification categories including race, myocardial infarction event age groups, and sex using several machine learning models on the literature-derived SNP data. We used visualization approaches to examine clustering of data as well as quantitative performance metrics for the classification of the risk factors examined above. Our method outperformed all popular dimensionality reduction and visualization methods for both classification and visualization, and it is robust against missing and higher-dimensional data. Moreover, we found it feasible to incorporate both genetic and other risk information obtained from literature with our method.

Mechanisms of damage to sperm structure in mice on the zinc-deficient diet

BACKGROUND

Zinc (Zn)is an essential trace element for spermatogenesis and its deficiency causes abnormal spermatogenesis.

OBJECTIVE

The present study was conducted to examine the mechanisms by which Zn-deficient diet impairs sperm morphology and its reversibility.

METHODS

30 SPF grade male Kunming (KM) mice were randomly divided into three groups, 10 mice per group. Zn-normal diet group (ZN group) was given Zn-normal diet（Zn content= 30 mg/kg）for 8 weeks. Zn-deficienct diet group (ZD group) was given Zn-deficienct diet（Zn content< 1 mg/kg）for 8 weeks. Zn-deficient and Zn-normal diet group（ZDN group）was given 4 weeks Zn-deficienct diet followed by 4 weeks Zn-normal diet. After 8 weeks, the overnight fasted mice were sacrificed, and blood and organs were collected for further analysis.

RESULTS

The experimental results showed that Zn-deficienct diet leads to increased abnormal morphology sperm and testicular oxidative stress.The rate of abnormal morphology sperm, chromomycin A3(CMA3), DNA fragmentation index (DFI), malondialdehyde (MDA) were significantly increased, and a-kinase anchor protein 4(AKAP4), dynein axonemal heavy chain 1(DNAH1), sperm associated antigen 6(SPAG6), cilia and flagella associated protein 44(CFAP44), glutathione peroxidase (GSH-PX), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), nuclear factor erythroid 2-related factor (NRF2), NAD(P)H:quinone oxidoreductase 1(NQO1)and heme oxygenase 1(HO1) were significantly decreased in the ZD group mice. While the changes in above indicators caused by Zn-deficient diet were significantly alleviated in the ZDN group.

CONCLUSION

It was concluded that Zn-deficient diet causes abnormal morphology sperm and testicular oxidative stress in male mice. Abnormal morphology sperm caused by Zn-deficient diet are reversible, and Zn-normal diet can alleviate them.

CFAP70 is a solid and valuable target for the genetic diagnosis of oligo-astheno-teratozoospermia in infertile men

BACKGROUND

Male infertility is a worldwide population health concern, but its aetiology remains largely understood. Although CFAP70 variants have already been reported in two oligo-astheno-teratozoospermia (OAT) individuals by sequencing, animal evidence to support CFAP70 as a credible OAT-pathogenic gene is lacking.

METHOD

Cfap70-KO mice were generated to explore the physiological role of CFAP70. CFAP70 variants were detected in infertile men with OAT by whole exome sequencing and Sanger sequencing confirmation. Cfap70-truncated mice were further generated to explore the pathogenicity of the nonsense variant of CFAP70 identified in the proband.

FINDINGS

Here, we demonstrate that Cfap70-KO mice are sterile mainly due to OAT and further identify a Chinese infertile man carrying a homozygous nonsense variant (c.2962C > T/p.R988X) of CFAP70. Cfap70-truncated mice lacking 5-8 tetratricopeptide repeats (TPRs) mimic the patient's symptoms. CFAP70 is required for the biogenesis of spermatid flagella partially by regulating the expression of OAT-associated proteins (e.g., QRICH2), assisting the cytoplasmic preassembly of the calmodulin- and radial spoke-associated complex (CSC), and controlling the manchette localization of axoneme-related proteins. Moreover, we suggest that CFAP70-associated male infertility could be overcome by intracytoplasmic sperm injection (ICSI) treatment.

INTERPRETATION

Overall, we demonstrate that CFAP70 is necessary to assemble spermatid flagella and that CFAP70 gene could be used as a diagnostic target for male infertility with OAT in the clinic.

FUNDING

This study was supported by the National Key Research and Development Project (2019YFA0802101 to S.C), Open Fund of Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education (to S.C), Central Government to Guide Local Scientific and Technological Development (ZY21195023 to B.W), and Basic Research Projects of Central Scientific Research Institutes (to B.W).

The cilia and flagella associated protein CFAP52 orchestrated with CFAP45 is required for sperm motility in mice

Asthenozoospermia characterized by decreased sperm motility is a major cause of male infertility, but the majority of their etiology remains unknown. Here, we showed that the cilia and flagella associated protein 52 (Cfap52) gene was predominantly expressed in testis and its deletion in a Cfap52 knockout mouse model resulted in decreased sperm motility and male infertility. Cfap52 knockout also led to the disorganization of midpiece-principal piece junction of the sperm tail, but had no effect on the axoneme ultrastructure in spermatozoa. Furthermore, we found that CFAP52 interacted with the cilia and flagella associated protein 45 (CFAP45), and knockout of Cfap52 decreased the expression level of CFAP45 in sperm flagellum, which further disrupted the microtubule sliding produced by dynein ATPase. Together, our studies demonstrate that CFAP52 plays an essential role in sperm motility by interacting with CFAP45 in sperm flagellum, providing insights into the potential pathogenesis of the infertility of the human CFAP52 mutations.

BBOF1 is required for sperm motility and male fertility by stabilizing the flagellar axoneme in mice

The sperm flagellum is a specialized type of motile cilium composed of a typical "9 + 2" axonemal structure with peri-axonemal structures, such as outer dense fibers (ODFs). This flagellar arrangement is crucial for sperm movement and fertilization. However, the association of axonemal integrity with ODFs remains poorly understood. Here, we demonstrate that mouse BBOF1 could interact with both MNS1, an axonemal component, and ODF2, an ODF protein, and is required for sperm flagellar axoneme maintenance and male fertility. BBOF1 is expressed exclusively in male germ cells from the pachytene stage onwards and is detected in sperm axoneme fraction. Spermatozoa derived from Bbof1-knockout mice exhibit a normal morphology, however, reduced motility due to the absence of certain microtubule doublets, resulting in the failure to fertilize mature oocytes. Furthermore, BBOF1 is found to interact with ODF2 and MNS1 and is also required for their stability. Our findings in mice suggest that Bbof1 could also be essential for human sperm motility and male fertility, thus is a novel potential candidate gene for asthenozoospermia diagnosis.

Sperm Motility Annotated Genes: Are They Associated with Impaired Fecundity?

Sperm motility is a prerequisite for achieving pregnancy, and alterations in sperm motility, along with sperm count and morphology, are commonly observed in subfertile men. The aim of the study was to determine whether the expression level of genes annotated with the Gene Ontology (GO) term 'sperm motility' differed in sperm collected from healthy men and men diagnosed with oligoasthenozoospermia. Reverse transcription quantitative real-time PCR (RT-qPCR), quantitative mass spectrometry (LC-MS/MS), and enrichment analyses were used to validate a set of 132 genes in 198 men present at an infertility clinic. Out of the 132 studied sperm-motility-associated genes, 114 showed differentially expressed levels in oligoasthenozoospermic men compared to those of normozoospermic controls using an RT-qPCR analysis. Of these, 94 genes showed a significantly lower expression level, and 20 genes showed a significantly higher expression level. An MS analysis of sperm from an independent cohort of healthy and subfertile men identified 692 differentially expressed proteins, of which 512 were significantly lower and 180 were significantly higher in oligoasthenozoospermic men compared to those of the normozoospermic controls. Of the 58 gene products quantified with both techniques, 48 (82.75%) showed concordant regulation. Besides the sperm-motility-associated proteins, the unbiased proteomics approach uncovered several novel proteins whose expression levels were specifically altered in abnormal sperm samples. Among these deregulated proteins, there was a clear overrepresentation of annotation terms related to sperm integrity, the cytoskeleton, and energy-related metabolism, as well as human phenotypes related to spermatogenesis and sperm-related abnormalities. These findings suggest that many of these proteins may serve as diagnostic markers of male infertility. Our study reveals an extended number of sperm-motility-associated genes with altered expression levels in the sperm of men with oligoasthenozoospermia. These genes and/or proteins can be used in the future for better assessments of male factor infertility.

Molecular genetic mechanisms of teratozoospermia

In recent years, the incidence of teratospermia has been increasing, and it has become a very important factor leading to male infertility. The research on the molecular mechanism of teratospermia is also progressing rapidly. This article briefly summarizes the clinical incidence of teratozoospermia, and makes a retrospective summary of related studies reported in recent years. Specifically discussing the relationship between gene status and spermatozoa, the review aims to provide the basis for the genetic diagnosis and gene therapy of teratozoospermia.

Truncating PICK1 Variant Identified in Azoospermia Affected Mitochondrial Dysfunction in Knockout Mice

OBJECTIVE

The protein interacting with C kinase 1 (PICK1) plays a critical role in vesicle trafficking, and its deficiency in sperm cells results in abnormal vesicle trafficking from Golgi to acrosome, which eventually disrupts acrosome formation and leads to male infertility.

METHODS

An azoospermia sample was filtered, and the laboratory detection and clinical phenotype indicated typical azoospermia in the patient. We sequenced all of the exons in the PICK1 gene and found that there was a novel homozygous variant in the PICK1 gene, c.364delA (p.Lys122SerfsX8), and this protein structure truncating variant seriously affected the biological function. Then we constructed a PICK1 knockout mouse model using clustered regularly interspaced short palindromic repeat cutting technology (CRISPRc).

RESULTS

The sperm from PICK1 knockout mice showed acrosome and nucleus abnormalities, as well as dysfunctional mitochondrial sheath formation. Both the total sperm and motility sperm counts were decreased in the PICK1 knockout mice compared to wild-type mice. Moreover, the mitochondrial dysfunction was verified in the mice. These defects in the male PICK1 knockout mice may have eventually led to complete infertility.

CONCLUSION

The c.364delA novel variant in the PICK1 gene associated with clinical infertility, and pathogenic variants in the PICK1 may cause azoospermia or asthenospermia by impairing mitochondrial function in both mice and humans.

New Mutations in DNHD1 Cause Multiple Morphological Abnormalities of the Sperm Flagella

Male infertility is a common and complex disease and presents as a wide range of heterogeneous phenotypes. Multiple morphological abnormalities of the sperm flagellum (MMAF) phenotype is a peculiar condition of extreme morphological sperm defects characterized by a mosaic of sperm flagellum defects to a total asthenozoospermia. At this time, about 40 genes were associated with the MMAF phenotype. However, mutation prevalence for most genes remains individually low and about half of individuals remain without diagnosis, encouraging us to pursue the effort to identify new mutations and genes. In the present study, an a cohort of 167 MMAF patients was analyzed using whole-exome sequencing, and we identified three unrelated patients with new pathogenic mutations in DNHD1, a new gene recently associated with MMAF. Immunofluorescence experiments showed that DNHD1 was totally absent from sperm cells from DNHD1 patients, supporting the deleterious effect of the identified mutations. Transmission electron microscopy reveals severe flagellum abnormalities of sperm cells from one mutated patient, which appeared completely disorganized with the absence of the central pair and midpiece defects with a shortened and misshapen mitochondrial sheath. Immunostaining of IFT20 was not altered in mutated patients, suggesting that IFT may be not affected by DNHD1 mutations. Our data confirmed the importance of DNHD1 for the function and structural integrity of the sperm flagellum. Overall, this study definitively consolidated its involvement in MMAF phenotype on a second independent cohort and enriched the mutational spectrum of the DNHD1 gene.

Diverse monogenic subforms of human spermatogenic failure

Non-obstructive azoospermia (NOA) is the most severe form of male infertility and typically incurable. Defining the genetic basis of NOA has proven challenging, and the most advanced classification of NOA subforms is not based on genetics, but simple description of testis histology. In this study, we exome-sequenced over 1000 clinically diagnosed NOA cases and identified a plausible recessive Mendelian cause in 20%. We find further support for 21 genes in a 2-stage burden test with 2072 cases and 11,587 fertile controls. The disrupted genes are primarily on the autosomes, enriched for undescribed human "knockouts", and, for the most part, have yet to be linked to a Mendelian trait. Integration with single-cell RNA sequencing data shows that azoospermia genes can be grouped into molecular subforms with synchronized expression patterns, and analogs of these subforms exist in mice. This analysis framework identifies groups of genes with known roles in spermatogenesis but also reveals unrecognized subforms, such as a set of genes expressed across mitotic divisions of differentiating spermatogonia. Our findings highlight NOA as an understudied Mendelian disorder and provide a conceptual structure for organizing the complex genetics of male infertility, which may provide a rational basis for disease classification.

Peptides from the croceine croaker (Larimichthys crocea) swim bladder attenuate busulfan-induced oligoasthenospermia in mice

CONTEXT

The swim bladder of the croceine croaker is believed to have a therapeutic effect on various diseases. However, there is no research about its effect on mammalian spermatogenesis.

OBJECTIVE

We investigated the swim bladder peptides (SBPs) effect on busulfan-induced oligoasthenospermia in mice.

MATERIALS AND METHODS

We first extracted SBP from protein hydrolysate of the croceine croaker swim bladder, and then five groups of ICR male mice were randomly assigned: control, control + SBP 60 mg/kg, busulfan, busulfan + SBP 30 mg/kg and busulfan + SBP 60 mg/kg. Mice received bilateral intratesticular injections of busulfan to establish oligoasthenospermia model. After treatment with SBP for 4 weeks, testis and epididymis were collected from all mice for further analysis.

RESULTS

After treatment with SBP 30-60 mg/kg for 4 weeks, epididymal sperm concentration and motility increased by 3.9-9.6- and 1.9-2.4-fold than those of oligoasthenospermia mice induced by busulfan. Meanwhile, histology showed that spermatogenic cells decreased, leading to increased lumen diameters and vacuolization in the busulfan group. These features were reversed by SBP treatment. RNA-sequencing analysis revealed that, compared with the busulfan group, Lin28b and Igf2bp1 expression related to germ cell proliferation, increased with a >1.5-fold change after SBP treatment. Additionally, PGK2 and Cfap69 mRNAs associated with sperm motility, also increased with a >1.5-fold change. Furthermore, these findings were validated by quantitative real-time PCR and Western blotting.

DISCUSSION AND CONCLUSIONS

This is the first reported evidence for the therapeutic effect of SBP on oligoasthenospermia. SBP may be a promising drug for oligoasthenospermia in humans.

Clinical detection, diagnosis and treatment of morphological abnormalities of sperm flagella: A review of literature

Sperm carries male genetic information, and flagella help move the sperm to reach oocytes. When the ultrastructure of the flagella is abnormal, the sperm is unable to reach the oocyte and achieve insemination. Multiple morphological abnormalities of sperm flagella (MMAF) is a relatively rare idiopathic condition that is mainly characterized by multiple defects in sperm flagella. In the last decade, with the development of high-throughput DNA sequencing approaches, many genes have been revealed to be related to MMAF. However, the differences in sperm phenotypes and reproductive outcomes in many cases are attributed to different pathogenic genes or different pathogenic mutations in the same gene. Here, we will review information about the various phenotypes resulting from different pathogenic genes, including sperm ultrastructure and encoding proteins with their location and functions as well as assisted reproductive technology (ART) outcomes. We will share our clinical detection and diagnosis experience to provide additional clinical views and broaden the understanding of this disease.

Intake of ultra-processed foods and asthenozoospermia odds: A hospital-based case-control study

Background

The intake of ultra-processed foods (UPFs) has increased rapidly in recent years. Evidence has suggested that UPFs has adverse effects on several health outcomes. This study aimed to first evaluate the association between the intake of UPFs and asthenozoospermia odds.

Methods

A hospital-based case-control study including 549 cases and 581 controls was performed in the infertility clinics of Shengjing Hospital of China Medical University from June 2020 to December 2020. Dietary intake was assessed using a validated food frequency questionnaire. Food items were categorized by the NOVA classification system based on the degree of processing. Semen parameters were analyzed according to the World Health Organization guidelines.

Results

The highest tertile of UPFs intake (% of total energy intake) was positively associated with the odds of asthenozoospermia (odds ratio [OR] = 1.53; 95% confidence interval [CI]: 1.12, 2.10; P for trend < 0.05), compared with the lowest tertile. Similar patterns were also found in subgroup analyses among participants with age ≥32 years (OR = 1.58; 95% CI: 1.04, 2.40), BMI ≥ 24 kg/m² (OR = 1.52; 95% CI: 1.04, 2.22), ever cigarette smoking (OR = 1.78; 95% CI: 1.14, 2.79), and ever alcohol drinking (OR = 1.65; 95% CI: 1.01, 2.72), and in sensitivity analyses by using absolute amount (g/day) to calculate the intake of UPFs.

Conclusion

Higher consumption of UPFs was positively associated with the odds of asthenozoospermia. More studies are needed to confirm our findings.

DNAH5 gene and its correlation with linc02220 expression and sperm characteristics

BACKGROUND

Numerous pieces of evidence show that many environmental and genetic factors can cause male infertility. Much research in recent years has investigated the function of long non-coding RNAs (lncRNAs) in fertility. The main objective of the current study was to investigate the expression of Dynein Axonemal Heavy Chain 5 (DNAH5) as a gene that plays an essential role in sperm motility in individuals with asthenozoospermia and terato-asthenozoospermia. Alterations in linc02220 expression (located close to the DNAH5 gene), its action potential in DNAH5 regulating, and the correlation between their expression and normal sperm morphology and motility were also examined.

METHOD AND MATERIAL

This study examined the semen of 31 asthenozoospermia individuals (AZ), 33 terato-asthenozoospermia (TAZ) individuals, and 33 normospermia (NZ) individuals with normal sperm as a control group. The expression levels of DNAH5 and linc02220 in the sperm samples were analyzed by real-time PCR.

RESULTS

Gene expression analysis revealed a significant association between DNAH5 expression and sperm motility and morphology (p < 0.0001). The DNAH5 expression levels in the TAZ and AZ groups were also significantly reduced; however, linc02220 was significantly upregulated in both TAZ and AZ groups compared to the NZ group (p < 0.0001). DNAH5 expression in the TAZ and AZ groups was negatively correlated with linc02220 expression, thus, DNAH5 downregulation was associated with linc02220 overexpression (p < 0.05).

CONCLUSIONS

The gene linc02220 could be a potential regulatory target for DNAH5, and both could affect sperm's normal motility and morphology.

LRRC46 Accumulates at the Midpiece of Sperm Flagella and Is Essential for Spermiogenesis and Male Fertility in Mouse

The sperm flagellum is essential for male fertility. Multiple morphological abnormalities of the sperm flagella (MMAF) is a severe form of asthenoteratozoospermia. MMAF phenotypes are understood to result from pathogenic variants of genes from multiple families including AKAP, DANI, DNAH, RSPH, CCDC, CFAP, TTC, and LRRC, among others. The Leucine-rich repeat protein (LRRC) family includes two members reported to cause MMAF phenotypes: Lrrc6 and Lrrc50. Despite vigorous research towards understanding the pathogenesis of MMAF-related diseases, many genes remain unknown underlying the flagellum biogenesis. Here, we found that Leucine-rich repeat containing 46 (LRRC46) is specifically expressed in the testes of adult mice, and show that LRRC46 is essential for sperm flagellum biogenesis. Both scanning electron microscopy (SEM) and Papanicolaou staining (PS) presents that the knockout of Lrrc46 in mice resulted in typical MMAF phenotypes, including sperm with short, coiled, and irregular flagella. The male KO mice had reduced total sperm counts, impaired sperm motility, and were completely infertile. No reproductive phenotypes were detected in Lrrc46-/- female mice. Immunofluorescence (IF) assays showed that LRRC46 was present throughout the entire flagella of control sperm, albeit with evident concentration at the mid-piece. Transmission electron microscopy (TEM) demonstrated striking flagellar defects with axonemal and mitochondrial sheath malformations. About the important part of the Materials and Methods, SEM and PS were used to observe the typical MMAF-related irregular flagella morphological phenotypes, TEM was used to further inspect the sperm flagellum defects in ultrastructure, and IF was chosen to confirm the location of protein. Our study suggests that LRRC46 is an essential protein for sperm flagellum biogenesis, and its mutations might be associated with MMAF that causes male infertility. Thus, our study provides insights for understanding developmental processes underlying sperm flagellum formation and contribute to further observe the pathogenic genes that cause male infertility.

Characterization of 2,2'4,4'-Tetrabromodiphenyl ether (BDE47)-induced testicular toxicity via single-cell RNA-sequencing

Background

The growing male reproductive diseases have been linked to higher exposure to certain environmental compounds such as 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) that are widely distributed in the food chain. However, the specific underlying molecular mechanisms for BDE47-induced male reproductive toxicity are not completely understood.

Methods

Here, for the first time, advanced single-cell RNA sequencing (ScRNA-seq) was employed to dissect BDE47-induced prepubertal testicular toxicity in mice from a pool of 76 859 cells.

Results

Our ScRNA-seq results revealed shared and heterogeneous information of differentially expressed genes, signaling pathways, transcription factors, and ligands-receptors in major testicular cell types in mice upon BDE47 treatment. Apart from disruption of hormone homeostasis, BDE47 was discovered to downregulate multiple previously unappreciated pathways such as double-strand break repair and cytokinesis pathways, indicative of their potential roles involved in BDE47-induced testicular injury. Interestingly, transcription factors analysis of ScRNA-seq results revealed that Kdm5b (lysine-specific demethylase 5B), a key transcription factor required for spermatogenesis, was downregulated in all germ cells as well as in Sertoli and telocyte cells in BDE47-treated testes of mice, suggesting its contribution to BDE47-induced impairment of spermatogenesis.

Conclusions

Overall, for the first time, we established the molecular cell atlas of mice testes to define BDE47-induced prepubertal testicular toxicity using the ScRNA-seq approach, providing novel insight into our understanding of the underlying mechanisms and pathways involved in BDE47-associated testicular injury at a single-cell resolution. Our results can serve as an important resource to further dissect the potential roles of BDE47, and other relevant endocrine-disrupting chemicals, in inducing male reproductive toxicity.

Multiomics analysis of male infertility

Infertility affects 8-12% of couples globally, and the male factor is a primary cause in approximately 50% of couples. Male infertility is a multifactorial reproductive disorder, which can be caused by paracrine and autocrine factors, hormones, genes, and epigenetic changes. Recent studies in rodents and most notably in humans using multiomics approach have yielded important insights into understanding the biology of spermatogenesis. Nonetheless, the etiology and pathogenesis of male infertility are still largely unknown. In this review, we summarized and critically evaluated findings based on the use of advanced technologies to compare normal and obstructive azoospermia (OA) versus non-obstructive azoospermia (NOA) men, including whole-genome bisulfite sequencing (WGBS), single cell RNA-seq (scRNA-seq), whole exome sequencing (WES), and ATAC-seq. It is obvious that the multiomics approach is the method of choice for basic research and clinical studies including clinical diagnosis of male infertility.

Homozygous Loss of Septin12, but not its Haploinsufficiency, Leads to Male Infertility and Fertilization Failure

The SEPTIN12 gene has been associated with male infertility. Male Septin12^+/− chimera mice were infertile, supporting the prevailing view that SEPTIN12 haploinsufficiency causes male infertility. In this study, we identified a heterozygous mutation on SEPTIN12, c.72C>A (p.Cys24Ter) in the male partner of a patient couple, who had a previous fertilization failure (FF) after intracytoplasmic sperm injection (ICSI) and became pregnant after ICSI together with artificial oocyte activation (AOA). To investigate the role of SEPTIN12 in FF and oocyte activation, we constructed Septin12 knockout mice. Surprisingly, Septin12^−/− male mice, but not Septin12^+/− male mice, are infertile, and have reduced sperm counts and abnormal sperm morphology. Importantly, AOA treatment enhances the 2-cell embryo rate of ICSI embryos injected with Septin12^−/− sperm, indicating that FF caused by male Septin12 deficiency is overcome by AOA. Mechanistically, loss of PLCζ around the acrosome might be the reason for FF of Septin12^−/− sperm. Taken together, our data indicated that homozygous knockout of Septin12, but not Septin12 haploinsufficiency, leads to male infertility and FF.

Ciliary central apparatus structure reveals mechanisms of microtubule patterning

A pair of extensively modified microtubules form the central apparatus (CA) of the axoneme of most motile cilia, where they regulate ciliary motility. The external surfaces of both CA microtubules are patterned asymmetrically with large protein complexes that repeat every 16 or 32 nm. The composition of these projections and the mechanisms that establish asymmetry and longitudinal periodicity are unknown. Here, by determining cryo-EM structures of the CA microtubules, we identify 48 different CA-associated proteins, which in turn reveal mechanisms for asymmetric and periodic protein binding to microtubules. We identify arc-MIPs, a novel class of microtubule inner protein, that bind laterally across protofilaments and remodel tubulin structure and lattice contacts. The binding mechanisms utilized by CA proteins may be generalizable to other microtubule-associated proteins. These structures establish a foundation to elucidate the contributions of individual CA proteins to ciliary motility and ciliopathies.

Reduced expression of CFAP44 and CFAP44-AS1 may affect sperm motility and morphology

Motility and morphology are two important characteristics of a fertile spermatozoon. CFAP44 gene encodes flagellar protein 44 involved in the formation and function of the flagella and cilia. Long non-coding RNAs are regulatory elements involved in several processes, including reproduction. We aimed to study the alterations in the expressions of CFAP44 and CFAP44-AS1 genes in infertile men with asthenozoospermia and terato-asthenozoospermia. In this case-control study, a total of 105 subjects, including 35 TAZ patients, 34 AZ patients and 35 normozoospermic men, were enrolled. After RNA extraction from spermatozoa samples, quantitative real-time PCR was performed to compare the expression of CFAP44 and CFAP44-AS1 between the studied groups. A meaningful reduction in CFAP44 expression and a significant reduction in the expression of CFAP44-AS1 were observed. Moreover, a positive correlation between both genes' expressions and normal sperm morphology was detected in NZ, AZ and TAZ groups. Also, there was a positive relation between CFAP44 gene expression and sperm motility in AZ and TAZ groups. The expression of CFAP44-AS1 was positively correlated with sperm motility and morphology. Present results confirm the role of CFAP44 and CFAP44-AS1 in the motility and morphology of spermatozoon, and deregulation of these genes may contribute to male infertility.

Oligogenic heterozygous inheritance of sperm abnormalities in mouse

Male infertility is an important health concern that is expected to have a major genetic etiology. Although high-throughput sequencing has linked gene defects to more than 50% of rare and severe sperm anomalies, less than 20% of common and moderate forms are explained. We hypothesized that this low success rate could at least be partly due to oligogenic defects – the accumulation of several rare heterozygous variants in distinct, but functionally connected, genes. Here, we compared fertility and sperm parameters in male mice harboring one to four heterozygous truncating mutations of genes linked to multiple morphological anomalies of the flagellum (MMAF) syndrome. Results indicated progressively deteriorating sperm morphology and motility with increasing numbers of heterozygous mutations. This first evidence of oligogenic inheritance in failed spermatogenesis strongly suggests that oligogenic heterozygosity could explain a significant proportion of asthenoteratozoospermia cases. The findings presented pave the way to further studies in mice and man.

PCD Genes-From Patients to Model Organisms and Back to Humans

Primary ciliary dyskinesia (PCD) is a hereditary genetic disorder caused by the lack of motile cilia or the assembxly of dysfunctional ones. This rare human disease affects 1 out of 10,000-20,000 individuals and is caused by mutations in at least 50 genes. The past twenty years brought significant progress in the identification of PCD-causative genes and in our understanding of the connections between causative mutations and ciliary defects observed in affected individuals. These scientific advances have been achieved, among others, due to the extensive motile cilia-related research conducted using several model organisms, ranging from protists to mammals. These are unicellular organisms such as the green alga Chlamydomonas, the parasitic protist Trypanosoma, and free-living ciliates, Tetrahymena and Paramecium, the invertebrate Schmidtea, and vertebrates such as zebrafish, Xenopus, and mouse. Establishing such evolutionarily distant experimental models with different levels of cell or body complexity was possible because both basic motile cilia ultrastructure and protein composition are highly conserved throughout evolution. Here, we characterize model organisms commonly used to study PCD-related genes, highlight their pros and cons, and summarize experimental data collected using these models.

Comparative Proteomics of the Acanthopagrus schlegelii Gonad in Different Sex Reversal

A substantial proportion of Acanthopagrus schlegelii individuals change sex from male to female during their lifetime. However, the mechanisms underlying sex change are unknown. In this research, iTRAQ analyses of proteins obtained from A.schlegelii gonads in four different stages of development were compared. In total, 4692 proteins were identified, including common sex-specific proteins, such as sperm-associated antigen 6 and cilia- and flagella-associated proteins in males, and zona pellucida sperm-binding proteins in females. Furthermore, proteins involved in the integrin signaling pathway, inflammation mediated by the chemokine and cytokine signaling pathways, pyruvate metabolism, CCKR signaling map, de novo purine biosynthesis and the ubiquitin proteasome pathway were upregulated in female gonads, whereas proteins implicated in DNA replication, the heterotrimeric G-protein signaling pathway, Gi alpha- and Gs alpha-mediated pathways, wnt signaling pathway, and hedgehog signaling pathway were upregulated in male gonads. Interestingly, cathepsins were only identified in ovaries, indicating their potential involvement in rapid ovarian development. Apoptosis-related proteins expressed in ovaries (such as MAPK and Cdc42) may protect them from cancer. This is the first report on the gonad proteome from A.schlegelii in different stages of sex reversal, and the results provide important fundamental data for studying the molecular mechanisms of sex reversal.

Mitochondrial regulation during male germ cell development

Mitochondria tailor their morphology to execute their specialized functions in different cell types and/or different environments. During spermatogenesis, mitochondria undergo continuous morphological and distributional changes with germ cell development. Deficiencies in these processes lead to mitochondrial dysfunction and abnormal spermatogenesis, thereby causing male infertility. In recent years, mitochondria have attracted considerable attention because of their unique role in the regulation of piRNA biogenesis in male germ cells. In this review, we describe the varied characters of mitochondria and focus on key mitochondrial factors that play pivotal roles in the regulation of spermatogenesis, from primordial germ cells to spermatozoa, especially concerning metabolic shift, stemness and reprogramming, mitochondrial transformation and rearrangement, and mitochondrial defects in human sperm. Further, we discuss the molecular mechanisms underlying these processes.

Molecular basis of the morphogenesis of sperm head and tail in mice

Background

The spermatozoon has a complex molecular apparatus necessary for fertilization in its head and flagellum. Recently, numerous genes that are needed to construct the molecular apparatus of spermatozoa have been identified through the analysis of genetically modified mice.

Methods

Based on the literature information, the molecular basis of the morphogenesis of sperm heads and flagella in mice was summarized.

Main findings (Results)

The molecular mechanisms of vesicular trafficking and intraflagellar transport in acrosome and flagellum formation were listed. With the development of cryo‐electron tomography and mass spectrometry techniques, the details of the axonemal structure are becoming clearer. The fine structure and the proteins needed to form the central apparatus, outer and inner dynein arms, nexin‐dynein regulatory complex, and radial spokes were described. The important components of the formation of the mitochondrial sheath, fibrous sheath, outer dense fiber, and the annulus were also described. The similarities and differences between sperm flagella and Chlamydomonas flagella/somatic cell cilia were also discussed.

Conclusion

The molecular mechanism of formation of the sperm head and flagellum has been clarified using the mouse as a model. These studies will help to better understand the diversity of sperm morphology and the causes of male infertility.

CFAP61 is required for sperm flagellum formation and male fertility in human and mouse

Defects in the structure or motility of cilia and flagella may lead to severe diseases such as primary ciliary dyskinesia (PCD), a multisystemic disorder with heterogeneous manifestations affecting primarily respiratory and reproductive functions. We report that CFAP61 is a conserved component of the calmodulin- and radial spoke-associated complex (CSC) of cilia. We find that a CFAP61 splice variant, c.143+5G>A, causes exon skipping/intron retention in human, inducing a multiple morphological abnormalities of the flagella (MMAF) phenotype. We generated Cfap61 knockout mice that recapitulate the infertility phenotype of the human CFAP61 mutation, but without other symptoms usually observed in PCD. We find that CFAP61 interacts with the CSC, radial spoke stalk and head. During early stages of Cfap61-/- spermatid development, the assembly of radial spoke components is impaired. As spermiogenesis progresses, the axoneme in Cfap61-/- cells becomes unstable and scatters, and the distribution of intraflagellar transport proteins is disrupted. This study reveals an organ-specific mechanism of axoneme stabilization that is related to male infertility.

Proteomic fertility markers in ram sperm

Precise estimation of ram fertility is important for sheep farming to sustain reproduction efficiency and profitability of production. There, however, is no conventional method to accurately predict ram fertility. The objective of this study, therefore, was to ascertain proteomic profiles of ram sperm having contrasting fertility phenotypes. Mature rams (n = 66) having greater pregnancy rates than average (89.4 ± 7.2%) were assigned into relatively-greater fertility (GF; n = 31; 94.5 ± 2.8%) whereas those with less-than-average pregnancy rates were assigned into a lesser-fertility (LF; n = 25; 83.1 ± 5.73%; P = 0.028) group. Sperm samples from the outlier greatest- and least-fertility rams (n = 6, pregnancy rate; 98.4 ± 1.8% and 76.1 ± 3.9%) were used for proteomics assessments utilizing Label-free LC-MS/MS. A total of 997 proteins were identified, and among these, 840 were shared by both groups, and 57 and 93 were unique to GF and LF, respectively. Furthermore, 190 differentially abundant proteins were identified; the abundance of 124 was larger in GF while 66 was larger in LF rams. The GF ram sperm had 79 GO/pathway terms in ten major biological networks while there were 47 GO/pathway terms in six biological networks in sperm of LF rams. Accordingly, differential abundances of sperm proteins between sperm of GF and LF rams were indicative of functional implications of sperm proteome on male fertility. The results of this study emphasize there are potential protein markers for evaluation of semen quality and estimation of ram sperm fertilizing capacity.

Genetic diagnosis, sperm phenotype and ICSI outcome in case of severe asthenozoospermia with multiple morphological abnormalities of the flagellum

STUDY QUESTION

Are ICSI outcomes impaired in cases of severe asthenozoospermia with multiple morphological abnormalities of the flagellum (MMAF phenotype)?

SUMMARY ANSWER

Despite occasional technical difficulties, ICSI outcomes for couples with MMAF do not differ from those of other couples requiring ICSI, irrespective of the genetic defect.

WHAT IS KNOWN ALREADY

Severe asthenozoospermia, especially when associated with the MMAF phenotype, results in male infertility. Recent findings have confirmed that a genetic aetiology is frequently responsible for this phenotype. In such situations, pregnancies can be achieved using ICSI. However, few studies to date have provided detailed analyses regarding the flagellar ultrastructural defects underlying this phenotype, its genetic aetiologies, and the results of ICSI in such cases of male infertility.

STUDY DESIGN, SIZE, DURATION

We performed a retrospective study of 25 infertile men exhibiting severe asthenozoospermia associated with the MMAF phenotype identified through standard semen analysis. They were recruited at an academic centre for assisted reproduction in Paris (France) between 2009 and 2017. Transmission electron microscopy (TEM) and whole exome sequencing (WES) were performed in order to determine the sperm ultrastructural phenotype and the causal mutations, respectively. Finally 20 couples with MMAF were treated by assisted reproductive technologies based on ICSI.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients with MMAF were recruited based on reduced sperm progressive motility and increased frequencies of absent, short, coiled or irregular flagella compared with those in sperm from fertile control men. A quantitative analysis of the several ultrastructural defects was performed for the MMAF patients and for fertile men. The ICSI results obtained for 20 couples with MMAF were compared to those of 378 men with oligoasthenoteratozoospermia but no MMAF as an ICSI control group.

MAIN RESULTS AND THE ROLE OF CHANCE

TEM analysis and categorisation of the flagellar anomalies found in these patients provided important information regarding the structural defects underlying asthenozoospermia and sperm tail abnormalities. In particular, the absence of the central pair of axonemal microtubules was the predominant anomaly observed more frequently than in control sperm (P < 0.01). Exome sequencing, performed for 24 of the 25 patients, identified homozygous or compound heterozygous pathogenic mutations in CFAP43, CFAP44, CFAP69, DNAH1, DNAH8, AK7, TTC29 and MAATS1 in 13 patients (54.2%) (11 affecting MMAF genes and 2 affecting primary ciliary dyskinesia (PCD)-associated genes). A total of 40 ICSI cycles were undertaken for 20 MMAF couples, including 13 cycles (for 5 couples) where a hypo-osmotic swelling (HOS) test was required due to absolute asthenozoospermia. The fertilisation rate was not statistically different between the MMAF (65.7%) and the non-MMAF (66.0%) couples and it did not differ according to the genotype or the flagellar phenotype of the subjects or use of the HOS test. The clinical pregnancy rate per embryo transfer did not differ significantly between the MMAF (23.3%) and the non-MMAF (37.1%) groups. To date, 7 of the 20 MMAF couples have achieved a live birth from the ICSI attempts, with 11 babies born without any birth defects.

LIMITATIONS, REASONS FOR CAUTION

The ICSI procedure outcomes were assessed retrospectively on a small number of affected subjects and should be confirmed on a larger cohort. Moreover, TEM analysis could not be performed for all patients due to low sperm concentrations, and WES results are not yet available for all of the included men.

WIDER IMPLICATIONS OF THE FINDINGS

An early and extensive phenotypic and genetic investigation should be considered for all men requiring ICSI for severe asthenozoospermia. Although our study did not reveal any adverse ICSI outcomes associated with MMAF, we cannot rule out that some rare genetic causes could result in low fertilisation or pregnancy rates.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study and there are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Successful birth after ICSI with testicular immotile spermatozoa from a patient with total MMAF in the ejaculates: a case report

There has been no report on the outcome of vitrified blastocyst transfer from a vitrified oocyte injected with immotile testicular spermatozoa with only multiple morphological abnormalities of the sperm flagella (MMAF). A couple diagnosed with MMAF returned to the clinic to attempt pregnancy using their vitrified oocytes. Testicular spermatozoa were injected intracytoplasmically, and the following intracytoplasmic sperm injection results were observed. In the second cycle, surplus vitrified oocytes and testicular retrieved sperm were used, but no pregnancy ensued. In the third cycle, a surplus vitrified blastocyst was transferred, and a healthy female child was delivered, with a birth weight of 3050 g and a birth length of 53 cm. In this report we describe a successful pregnancy achieved in a patient presenting MMAF. The successful pregnancy was obtained from vitrified oocytes microinjected with testicular retrieved sperm in a vitrified blastocyst transfer.

A novel stop-gain mutation in ARMC2 is associated with multiple morphological abnormalities of the sperm flagella

RESEARCH QUESTION

Male infertility is a global issue worldwide and multiple morphological abnormalities of the sperm flagella (MMAF) is one of the most severe forms of the qualitative sperm defects with a heterogeneous genetic cause that has not been completely understood. Can whole-exome sequencing (WES) reveal novel genetic causes contributing to MMAF in a consanguineous Pakistani family, comprising three infertile brothers?

DESIGN

WES and bioinformatic analysis were conducted to screen potential pathogenic variants. The identified variant was validated by Sanger sequencing in all available family members Transmission electron microscopy analyses was carried out to examine the flagella ultrastructure of spermatozoa from patient.

RESULTS

WES and Sanger sequencing identified a novel homozygous stop-gain mutation (ENST00000392644.4, c.182C>G, p.S61X) in ARMC2, which is expected to lead to loss of protein functions. Transmission electron microscopy analyses revealed that the flagellar ultrastructure of the patient's spermatozoa was disorganized along with a complete absence of central pair complex (CPC), suggesting that ARMC2 is involved in the assembly, stability of the axonemal complex, or both, particularly the CPC.

CONCLUSION

We report that a familial stop-gain mutation in ARMC2 is associated with male infertility in humans caused by MMAF accompanied with loss of CPCs and axonemal disorganization. We provide genetic evidence that ARMC2 is essential for human spermatogenesis and its mutation may be pathogenic for MMAF. These findings will improve the knowledge about the genetic basis of MMAF and provide information for genetic counselling of this disease.

Diagnostics and Management of Male Infertility in Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD), a disease caused by the malfunction of motile cilia, manifests mainly with chronic recurrent respiratory infections. In men, PCD is also often associated with infertility due to immotile sperm. Since causative mutations for PCD were identified in over 50 genes, the role of these genes in sperm development should be investigated in order to understand the effect of PCD mutations on male fertility. Previous studies showed that different dynein arm heavy chains are present in respiratory cilia and sperm flagellum, which may partially explain the variable effects of mutations on airways and fertility. Furthermore, recent studies showed that male reproductive tract motile cilia may play an important part in sperm maturation and transport. In some PCD patients, extremely low sperm counts were reported, which may be due to motile cilia dysfunction in the reproductive tract rather than problems with sperm development. However, the exact roles of PCD genes in male fertility require additional studies, as do the treatment options. In this review, we discuss the diagnostic and treatment options for men with PCD based on the current knowledge.

Autophagic elimination of ribosomes during spermiogenesis provides energy for flagellar motility

How autophagy initiation is regulated and what the functional significance of this regulation is are unknown. Here, we characterized the role of yeast Vac8 in autophagy initiation through recruitment of PIK3C3-C1 to the phagophore assembly site (PAS). This recruitment is dependent on the palmitoylation of Vac8 and on its middle ARM domains for binding PIK3C3-C1. Vac8-mediated anchoring of PIK3C3-C1 promotes PtdIns3P generation at the PAS and recruitment of the PtdIns3P binding protein Atg18-Atg2. The mouse homolog of Vac8, ARMC3, is conserved and functions in autophagy in mouse testes. Mice lacking ARMC3 have normal viability but show complete male infertility. Proteomic analysis indicated that the autophagic degradation of cytosolic ribosomes was blocked in ARMC3-deficient spermatids, which caused low energy levels of mitochondria and motionless flagella. These studies uncovered a function of Vac8/ARMC3 in PtdIns3-kinase anchoring at the PAS and its physical significance in mammalian spermatogenesis with a germ tissue-specific autophagic function.

Loss-of-function missense variant of AKAP4 induced male infertility through reduced interaction with QRICH2 during sperm flagella development

Sperm fibrous sheath is closely related to sperm maturation, capacitation and motility, and A-kinase anchor protein 4 (AKAP4) is the most abundant protein in sperm fibrous sheath. Previous studies found incomplete sperm fibrous sheaths and abnormal flagella in Akap4 knockout (KO) mice. Meanwhile, it was reported that the partial deletion in AKAP4 is highly relevant to the dysplasia of the fibrous sheath in an infertile man, and so far, there is no report about male infertility caused by hemizygous AKAP4 variant. Furthermore, the specific mechanisms of how the variant is relevant to the phenotype remain elusive. In this study, we investigated three multiple morphological abnormalities of the sperm flagella (MMAF)-affected men from three independent families (including one consanguine family) carried hemizygous c.C1285T variant in AKAP4. The patients carried thisvariant showed dysplastic sperm fibrous sheath and the protein expression of AKAP4 was decreased in flagella which was further confirmed in HEK-293 T cells in vitro. In addition, the co-localization and interaction between AKAP4 and glutamine-rich protein 2 (QRICH2) on the molecular level were identified by immunofluorescence and Co-immunoprecipitation (CO-IP). The hemizygous c.1285C > T variant in AKAP4 induced decreased protein expression of QRICH2 in spermatozoa. These results suggested that the normal expression of AKAP4 is required for maintaining the expression of QRICH2 and the decreased protein expression of AKAP4 and QRICH2，as well as the interaction between them induced by the hemizygous variant of AKAP4 caused dysplastic fibrous sheath, which eventually led to reduced sperm motility and male infertility.

Expression of miR-135a-5p and its target gene JAK2 in spermatozoa of patients with asthenozoospermia

This study aimed to identify the molecular mechanism by which JAK2 mRNA and microRNA-135a-5p (miR-135a-5p) affect asthenozoospermia. The expression levels of JAK2 mRNA in the spermatozoa of 30 asthenozoospermia patients and 30 normal controls were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). MiR-135a-5p that targeted JAK2 mRNA was predicted by bioinformatics. A dual luciferase reporter vector containing miR-135a-5p 3'UTR was constructed. The binding of miR-135a-5p to JAK2 mRNA was verified by luciferase reporter assay. The protein expression levels of JAK2 and STAT3 in spermatozoa were examined by Western bolt. The relative expression levels of JAK2 mRNA and protein in the asthenozoospermia group were significantly lower than those of the normal group. MiR-135a-5p overexpression inhibited JAK2 mRNA and protein expression by targeting JAK2 mRNA 3'UTR. Correlation analysis showed that miR-135a-5p level was significantly negatively correlated with progressive sperm motility, while JAK2 mRNA level was significantly positively correlated with progressive sperm activity. Low expression of JAK2 mRNA and high expression of miR-135a-5p were related to asthenozoospermia and male infertility.

Insight on multiple morphological abnormalities of sperm flagella in male infertility: what is new?

The syndrome of multiple morphological abnormalities of the sperm flagella (MMAF) is a specific kind of asthenoteratozoospermia with a mosaic of flagellar morphological abnormalities (absent, short, bent, coiled, and irregular flagella). MMAF was proposed in 2014 and has attracted increasing attention; however, it has not been clearly understood. In this review, we elucidate the definition of MMAF from a systematical view, the difference between MMAF and other conditions with asthenoteratozoospermia or asthenozoospermia (such as primary mitochondrial sheath defects and primary ciliary dyskinesia), the knowledge regarding its etiological mechanism and related genetic findings, and the clinical significance of MMAF for intracytoplasmic sperm injection and genetic counseling. This review provides the basic knowledge for MMAF and puts forward some suggestions for further investigations.

Towards Post-Meiotic Sperm Production: Genetic Insight into Human Infertility from Mouse Models

Declined quality and quantity of sperm is currently the major cause of patients suffering from infertility. Male germ cell development is spatiotemporally regulated throughout the whole developmental process. While it has been known that exogenous factors, such as environmental exposure, diet and lifestyle, et al, play causative roles in male infertility, recent progress has revealed abundant genetic mutations tightly associated with defective male germline development. In mammals, male germ cells undergo dramatic morphological change (i.e., nuclear condensation) and chromatin remodeling during post-meiotic haploid germline development, a process termed spermiogenesis; However, the molecular machinery players and functional mechanisms have yet to be identified. To date, accumulated evidence suggests that disruption in any step of haploid germline development is likely manifested as fertility issues with low sperm count, poor sperm motility, aberrant sperm morphology or combined. With the continually declined cost of next-generation sequencing and recent progress of CRISPR/Cas9 technology, growing studies have revealed a vast number of disease-causing genetic variants associated with spermiogenic defects in both mice and humans, along with mechanistic insights partially attained and validated through genetically engineered mouse models (GEMMs). In this review, we mainly summarize genes that are functional at post-meiotic stage. Identification and characterization of deleterious genetic variants should aid in our understanding of germline development, and thereby further improve the diagnosis and treatment of male infertility.

Exome sequencing reveals variants in known and novel candidate genes for severe sperm motility disorders

STUDY QUESTION

What are the causative genetic variants in patients with male infertility due to severe sperm motility disorders?

SUMMARY ANSWER

We identified high confidence disease-causing variants in multiple genes previously associated with severe sperm motility disorders in 10 out of 21 patients (48%) and variants in novel candidate genes in seven additional patients (33%).

WHAT IS KNOWN ALREADY

Severe sperm motility disorders are a form of male infertility characterised by immotile sperm often in combination with a spectrum of structural abnormalities of the sperm flagellum that do not affect viability. Currently, depending on the clinical sub-categorisation, up to 50% of causality in patients with severe sperm motility disorders can be explained by pathogenic variants in at least 22 genes.

STUDY DESIGN, SIZE, DURATION

We performed exome sequencing in 21 patients with severe sperm motility disorders from two different clinics.

PARTICIPANTS/MATERIALS, SETTING, METHOD

Two groups of infertile men, one from Argentina (n = 9) and one from Australia (n = 12), with clinically defined severe sperm motility disorders (motility <5%) and normal morphology values of 0–4%, were included. All patients in the Argentine cohort were diagnosed with DFS-MMAF, based on light and transmission electron microscopy. Sperm ultrastructural information was not available for the Australian cohort. Exome sequencing was performed in all 21 patients and variants with an allele frequency of <1% in the gnomAD population were prioritised and interpreted.

MAIN RESULTS AND ROLE OF CHANCE

In 10 of 21 patients (48%), we identified pathogenic variants in known sperm assembly genes: CFAP43 (3 patients); CFAP44 (2 patients), CFAP58 (1 patient), QRICH2 (2 patients), DNAH1 (1 patient) and DNAH6 (1 patient). The diagnostic rate did not differ markedly between the Argentinian and the Australian cohort (55% and 42%, respectively). Furthermore, we identified patients with variants in the novel human candidate sperm motility genes: DNAH12, DRC1, MDC1, PACRG, SSPL2C and TPTE2. One patient presented with variants in four candidate genes and it remains unclear which variants were responsible for the severe sperm motility defect in this patient.

LARGE SCALE DATA

N/A

LIMITATIONS, REASONS FOR CAUTION

In this study, we described patients with either a homozygous or two heterozygous candidate pathogenic variants in genes linked to sperm motility disorders. Due to unavailability of parental DNA, we have not assessed the frequency of de novo or maternally inherited dominant variants and could not determine the parental origin of the mutations to establish in all cases that the mutations are present on both alleles.

WIDER IMPLICATIONS OF THE FINDINGS

Our results confirm the likely causal role of variants in six known genes for sperm motility and we demonstrate that exome sequencing is an effective method to diagnose patients with severe sperm motility disorders (10/21 diagnosed; 48%). Furthermore, our analysis revealed six novel candidate genes for severe sperm motility disorders. Genome-wide sequencing of additional patient cohorts and re-analysis of exome data of currently unsolved cases may reveal additional variants in these novel candidate genes.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported in part by funding from the Australian National Health and Medical Research Council (APP1120356) to M.K.O.B., J.A.V. and R.I.M.L., The Netherlands Organisation for Scientific Research (918-15-667) to J.A.V., the Royal Society and Wolfson Foundation (WM160091) to J.A.V., as well as an Investigator Award in Science from the Wellcome Trust (209451) to J.A.V. and Grants from the National Research Council of Argentina (PIP 0900 and 4584) and ANPCyT (PICT 9591) to H.E.C. and a UUKi Rutherford Fund Fellowship awarded to B.J.H.

Composition and function of the C1b/C1f region in the ciliary central apparatus

Motile cilia are ultrastructurally complex cell organelles with the ability to actively move. The highly conserved central apparatus of motile 9 × 2 + 2 cilia is composed of two microtubules and several large microtubule-bound projections, including the C1b/C1f supercomplex. The composition and function of C1b/C1f subunits has only recently started to emerge. We show that in the model ciliate Tetrahymena thermophila, C1b/C1f contains several evolutionarily conserved proteins: Spef2A, Cfap69, Cfap246/LRGUK, Adgb/androglobin, and a ciliate-specific protein Tt170/TTHERM_00205170. Deletion of genes encoding either Spef2A or Cfap69 led to a loss of the entire C1b projection and resulted in an abnormal vortex motion of cilia. Loss of either Cfap246 or Adgb caused only minor alterations in ciliary motility. Comparative analyses of wild-type and C1b-deficient mutant ciliomes revealed that the levels of subunits forming the adjacent C2b projection but not C1d projection are greatly reduced, indicating that C1b stabilizes C2b. Moreover, the levels of several IFT and BBS proteins, HSP70, and enzymes that catalyze the final steps of the glycolytic pathway: enolase ENO1 and pyruvate kinase PYK1, are also reduced in the C1b-less mutants.