Sperm defects in primary ciliary dyskinesia and related causes of male infertility

Human asthenozoospermia: Update on genetic causes, patient management, and clinical strategies

BACKGROUND

In mammals, sperm fertilization potential relies on efficient progression within the female genital tract to reach and fertilize the oocyte. This fundamental property is supported by the flagellum, an evolutionarily conserved organelle, which contains dynein motor proteins that provide the mechanical force for sperm propulsion and motility. Primary motility of the sperm cells is acquired during their transit through the epididymis and hyperactivated motility is acquired throughout the journey in the female genital tract by a process called capacitation. These activation processes rely on the micro-environment of the genital tracts. In particular, during capacitation, a panoply of ion transporters located at the surface of the sperm cells mediate complex ion exchanges, which induce an increase in plasma membrane fluidity, the alkalinization of the cytoplasm and protein phosphorylation cascades that are compulsory for sperm hyperactivation and fertilization potential. As a consequence, both structural and functional defects of the sperm flagellum can affect sperm motility, resulting in asthenozoospermia, which constitutes the most predominant pathological condition associated with human male infertility.

OBJECTIVES

Herein, we have performed a literature review to provide a comprehensive description of the recent advances in the genetics of human asthenozoospermia.

RESULTS AND DISCUSSION

We describe the currently knowledge on gene mutations that affect sperm morphology and motility, namely, asthenoteratozoospermia; we also specify the gene mutations that exclusively affect sperm function and activation, resulting in functional asthenozoospermia. We discuss the benefit of this knowledge for patient and couple management, in terms of genetic counselling and diagnosis of male infertility as a sole phenotype or in association with ciliary defects. Last, we discuss the current strategies that have been initiated for the development of potential therapeutical and contraceptive strategies targeting genes that are essential for sperm function and activation.

1700030J22RIK is essential for sperm flagellar function and male fertility in mice

Spermiogenesis is an indispensable process occurring during the later stages of spermatogenesis. Despite multiple proteins being associated with spermiogenesis, the molecular mechanisms that control spermiogenesis remain poorly characterized. In this study, we show that 1700030J22RIK is exclusively expressed in the testis of mice and investigate its roles in spermiogenesis using genetic and proteomic approaches. The deficiency in 1700030J22RIK in male mice results in severe subfertility, characterized by a substantial decrease in sperm concentration, motility, and abnormalities in the flagella. Furthermore, 1700030J22RIK interacts with the A-kinase-anchoring protein AKAP3, and 1700030J22RIK knockout decreases AKAP3 and AKAP4 protein levels. Additionally, the absence of 1700030J22RIK alters spermatozoal levels of the subunits of protein kinase A, leading to reduced protein phosphorylation and impaired sperm motility. This study reveals that 1700030J22RIK plays a crucial role in the organization of sperm morphology and function in mice.

Primary ciliary dyskinesia as a rare cause of male infertility: case report and literature overview

BACKGROUND

Primary ciliary dyskinesia (PCD) is a heterogenous disease caused by mutations of miscellaneous genes which physiologically play an important role in proper structure and/or function of various cellular cilia including sperm flagella. Besides male infertility, the typical phenotypes, based on decreased mucociliary clearance, are lifelong respiratory issues, i.e., chronic bronchitis leading to bronchiectasis, chronic rhinosinusitis, and chronic otitis media. Moreover, since motile cilia are important during embryological development in the sense of direction of gut rotation, 50% of affected individuals develop situs inversus - so-called Kartagener's syndrome.

CASE PRESENTATION

We present two cases of PCD as a rare cause of male infertility.

CONCLUSIONS

Primary ciliary dyskinesia should be suspected in infertile males having (sub)normal sperm concentration values with persistent zero motility together with patient's and/or family history of respiratory symptoms like bronchiectasis, chronic cough, rhinitis, recurrent sinusitis, and otitis media. Due to more than 50 identified mutations until now, the causal mechanism of male infertility is miscellaneous and not in all cases known in detail. Besides impaired sperm motility, other mechanisms significantly decreasing efficacy of assisted reproduction techniques play a pivotal role. Thus, proper diagnostic work-up including, among others, sperm DNA fragmentation, is mandatory to avoid ineffective treatment burden.

The lncRNA Gm8097 is associated with hypospermatogenesis

OBJECTIVE

To investigate whether long non-coding RNA (lncRNA) Gm8097 (LncGm8097) is associated with male infertility.

METHODS

The expression and bilogical role of LncGm8097 were investigated.

RESULTS

LncGm8097 expression was down-regulated in the testis tissues with moderate and severe hypospermatogenesis compared with those with normal spermatogenesis and mild hypospermatogenesis (p<0.05). LncGm8097 down-regulation significantly promoted apoptosis and inhibited proliferation in GC1 and GC2 cells. In addition, LncGm8097 was significantly down-regulated in mouse model of hypospermatogenesis and correlated with cell apoptosis and proliferation. LncGm8097 was located immediately upstream of PRPS2, and correlated with Bcl-2/P53/caspase 6/caspase 9 signal pathway.

CONCLUSION

LncGm8097 down-regulation correlates with hypospermatogenesis, which may offer new insights into the pathogenesis of male infertility.

Motile Cilia in Female and Male Reproductive Tracts and Fertility

Motile cilia are evolutionarily conserved organelles. In humans, multiciliated cells (MCCs), assembling several hundred motile cilia on their apical surface, are components of the monolayer epithelia lining lower and upper airways, brain ventricles, and parts of the reproductive tracts, the fallopian tube and uterus in females, and efferent ductules in males. The coordinated beating of cilia generates a force that enables a shift of the tubular fluid, particles, or cells along the surface of the ciliated epithelia. Uncoordinated or altered cilia motion or cilia immotility may result in subfertility or even infertility. Here, we summarize the current knowledge regarding the localization and function of MCCs in the human reproductive tracts, discuss how cilia and cilia beating-generated fluid flow directly and indirectly contribute to the processes in these organs, and how lack or improper functioning of cilia influence human fertility.

Novel variants in DNAH9 are present in two infertile patients with severe asthenospermia

Asthenospermia is a type of sperm that has malformed sperm with movement disorders that lead to male infertility. DNAH9 is a member of the dynein family and a central part of the outer dynein arm of cilia and flagella. DNAH9 gene defects are associated with primary ciliary dyskinesia and ultrastructural abnormalities in ciliary axial ultrastructure. However, the role of DNAH9 in sperm motility remains unclear, prompting us to investigate its function in spermatozoa. Familial Sanger sequencing showed that sterile males carried homozygous DNAH9 variants (c. 12218A>C, p. N4073T) and compound heterozygous variants (c.8617G>A, p.V2873M; c.11742A>T, p.E3914D), respectively. Transmission electron microscopy revealed these variants resulted in a significant lack of outer dynein arms in the cross-sectional view of the axoneme in both patients. Immunofluorescence results showed that these variants can lead to decline in DNAH9 protein expression, which led to the dysfunction of flagellar ultrastructure-related proteins, including DNAI1, DNAH1 and DNAH10. In conclusion, we identified novel biallelic variants in DNAH9 that likely bring about sharply decreased motility of spermatozoa in the two patients with asthenospermia. Our findings will widen the variant spectrum of known DNAH9 variants involving asthenospermia and further offer more proofs for genetic counseling and diagnosis.

DNAH3 deficiency causes flagellar inner dynein arm loss and male infertility in humans and mice

Axonemal protein complexes, including the outer and inner dynein arms (ODA/IDA), are highly ordered structures of the sperm flagella that drive sperm motility. Deficiencies in several axonemal proteins have been associated with male infertility, which is characterized by asthenozoospermia or asthenoteratozoospermia. Dynein axonemal heavy chain 3 (DNAH3) resides in the IDA and is highly expressed in the testis. However, the relationship between DNAH3 and male infertility is still unclear. Herein, we identified biallelic variants of DNAH3 in four unrelated Han Chinese infertile men with asthenoteratozoospermia through whole-exome sequencing (WES). These variants contributed to deficient DNAH3 expression in the patients' sperm flagella. Importantly, the patients represented the anomalous sperm flagellar morphology, and the flagellar ultrastructure was severely disrupted. Intriguingly, Dnah3 knockout (KO) male mice were also infertile, especially showing the severe reduction in sperm movement with the abnormal IDA and mitochondrion structure. Mechanically, nonfunctional DNAH3 expression resulted in decreased expression of IDA-associated proteins in the spermatozoa flagella of patients and KO mice, including DNAH1, DNAH6, and DNALI1, the deletion of which has been involved in disruption of sperm motility. Moreover, the infertility of patients with DNAH3 variants and Dnah3 KO mice could be rescued by intracytoplasmic sperm injection (ICSI) treatment. Our findings indicated that DNAH3 is a novel pathogenic gene for asthenoteratozoospermia and may further contribute to the diagnosis, genetic counseling, and prognosis of male infertility.

Structure and function of FAP47 in the central pair apparatus of Chlamydomonas flagella

Motile cilia have a so-called "9 + 2" structure, which consists of nine doublet microtubules and a central pair apparatus. The central pair apparatus (CA) is thought to interact mechanically with radial spokes and to control the flagellar beating. Recently, the components of the CA have been identified by proteomic and genomic analyses. Still, the mechanism of how the CA contributes to ciliary motility has much to be revealed. Here, we focused on one CA component with a large molecular weight: FAP47, and its relationship with two other CA components with large molecular weight: HYDIN, and CPC1. The analyses of motility of the Chlamydomonas mutants revealed that in contrast to cpc1 or hydin, which swam more slowly than the wild type, fap47 cells displayed wild-type swimming velocity and flagellar beat frequency, yet interestingly, fap47 cells have phototaxis defects and swim straighter than the wild-type cells. Furthermore, the double mutant fap47cpc1 and fap47hydin showed significantly slower swimming than cpc1 and hydin cells, and the motility defect of fap47cpc1 was rescued to the cpc1 level with GFP-tagged FAP47, indicating that the lack of FAP47 makes the motility defect of cpc1 worse. Cryo-electron tomography demonstrated that the fap47 lacks a part of the C1-C2 bridge of CA. Taken together, these observations indicate that FAP47 maintains the structural stiffness of the CA, which is important for flagellar regulation.

A novel missense mutation of CCDC34 causes male infertility with oligoasthenoteratozoospermia in a consanguineous Pakistani family

ABSTRACT

Male infertility is a worldwide health issue, affecting 8%-12% of the global population. Oligoasthenoteratozoospermia (OAT) represents a severe type of male infertility, characterized by reduced sperm count and motility and an increased frequency of sperm with aberrant morphology. Using whole-exome sequencing, this study identified a novel missense mutation (c.848C>A, p.A283E) in the coiled-coil domain-containing 34 gene (CCDC34) in a consanguineous Pakistani family. This rare mutation was predicted to be deleterious and to affect the protein stability. Hematoxylin and eosin staining of spermatozoa from the patient with OAT revealed multiple morphological abnormalities of the flagella and transmission electron microscopy indicated axonemal ultrastructural defects with a lack of outer dynein arms. These findings indicated that CCDC34 plays a role in maintaining the axonemal ultrastructure and the assembly or stability of the outer dynein arms, thus expanding the phenotypic spectrum of CCDC34 missense mutations.

Novel bi-allelic DNAH3 variants cause oligoasthenoteratozoospermia

Background

Oligoasthenoteratozoospermia (OAT) is a widespread cause of male infertility. One of the usual clinical manifestations of OAT is multiple morphological abnormalities of the sperm flagella (MMAF), which are frequently associated with mutations and defects in the dynein family. However, the relationship between the newly identified Dynein Axonemal Heavy Chain 3 (DNAH3) mutation and oligonasthenospermia in humans has not yet been established.

Methods

Whole exome sequencing, pathogenicity analysis, and species conservation analysis of mutation sites were conducted on two patients from different unrelated families with DNAH3 mutations. We identified representative mutation sites and predicted the protein structure following these mutations. The sperm characteristics of the two patients with DNAH3 mutations were verified using Papanicolaou staining, scanning electron microscopy, and transmission electron microscopy. Additionally, mRNA and protein levels were assessed through RT-qPCR and Western blotting.

Results

The biallelic mutations in the first progenitor included a heterozygous deletion and insertion, c.6535_6536 delinsAC (to infect mutation (p.Asp2179Thr), and stop codon premutation, c.3249G > A (p.Trp1083Ter). In Family II, the patient (P2) harbored a DNAH3 heterozygous missense mutation, c. 10439G> A(p.Arg3480Gln), along with a stop codon premutation, (c.10260G > A; p.Trp3420Ter). Patients with premature termination of transcription or translation due to DNAH3 mutations exhibit OAT phenotypes, including fibrous sheath dysplasia and multiple tail malformations. We identified the representative sites after mutation, predicted the protein structure, and assessed changes in the protein levels of DNAH3 and related genes following mutations. Notably,a significant reduction in DNAH3 protein expression was validated in these patients. We may explore in the future how DNAH3 affects sperm motility and quality through regulatory mechanisms involving protein structural changes.

Conclusion

Novel biallelic mutations in DNAH3, especially those resulting in a premature stop codon, may alter protein expression, structure, and active site, leading to spermatogenic failure and potentially inducing OAT. The discovery of new mutations in DNAH3 may be the key to the diagnosis and treatment of OAT.

Association of novel DNAH11 variants with asthenoteratozoospermia lead to male infertility

BACKGROUND

Bi-allelic variants in DNAH11 have been identified as causative factors in Primary Ciliary Dyskinesia, leading to abnormal respiratory cilia. Nonetheless, the specific impact of these variants on human sperm flagellar and their involvement in male infertility remain largely unknown.

METHODS

A collaborative effort involving two Chinese reproductive centers conducted a study with 975 unrelated infertile men. Whole-exome sequencing was employed for variant screening, and Sanger sequencing confirmed the identified variants. Morphological and ultrastructural analyses of sperm were conducted using Scanning Electron Microscopy and Transmission Electron Microscopy. Western Blot Analysis and Immunofluorescence Analysis were utilized to assess protein levels and localization. ICSI was performed to evaluate its efficacy in achieving favorable pregnancy outcomes for individuals with DNAH11 variants.

RESULTS

In this study, we identified seven novel variants in the DNAH11 gene in four asthenoteratozoospermia subjects. These variants led the absence of DNAH11 proteins and ultrastructure defects in sperm flagella, particularly affecting the outer dynein arms (ODAs) and adjacent structures. The levels of ODA protein DNAI2 and axoneme related proteins were down regulated, instead of inner dynein arms (IDA) proteins DNAH1 and DNAH6. Two out of four individuals with DNAH11 variants achieved clinical pregnancies through ICSI. The findings confirm the association between male infertility and bi-allelic deleterious variants in DNAH11, resulting in the aberrant assembly of sperm flagella and contributing to asthenoteratozoospermia. Importantly, ICSI emerges as an effective intervention for overcoming reproductive challenges caused by DNAH11 gene variants.

A novel homozygous mutation in the DNAAF3 gene leads to severe asthenozoospermia and teratospermia

Primary ciliary dyskinesia (PCD) is an autosomal recessive genetic disorder characterized by ultrastructural defects in the cilia or flagella of cells, causing respiratory abnormalities, sinusitis, visceral transposition, and male infertility. DNAAF3 plays an important role in the assembly and transportation of axonemal dynein complexes in cilia or flagella and has been shown to be associated with PCD. To date, only two cases of PCD with infertility associated with DNAAF3 mutations have been reported, and no mouse models for this gene have been successfully constructed. This study was conducted on an infertile Chinese male patient with a history of bronchitis. Examination of the patient's semen revealed severe asthenozoospermia and teratospermia. Whole exome sequencing revealed a new homozygous loss-of-function DNAAF3 mutation. CRISPR-Cas9 gene-editing technology was used to construct the same mutation in C57/B6 mice, revealing that homozygous C57/B6 mice were characterized by severe hydrocephalus and early death. The results of this study expand the mutation spectrum of DNAAF3 and confirm its correlation with PCD pathogenesis. This study provides new insights on the mechanisms underlying male infertility related to DNAAF3 mutation and PCD.

The Domestication of Wild Boar Could Result in a Relaxed Selection for Maintaining Olfactory Capacity

Domesticated animals are artificially selected to exhibit desirable traits, however not all traits of domesticated animals are the result of deliberate selection. Loss of olfactory capacity in the domesticated pig (Sus scrofa domesticus) is one example. We used whole transcriptome analysis (RNA-Seq) to compare patterns of gene expression in the olfactory mucosa of the pig and two subspecies of wild boar (Sus scrofa), and investigate candidate genes that could be responsible for the loss of olfactory capacity. We identified hundreds of genes with reductions in transcript abundance in pig relative to wild boar as well as differences between the two subspecies of wild boar. These differences were detected mainly in genes involved in the formation and motility of villi, cilia and microtubules, functions associated with olfaction. In addition, differences were found in the abundances of transcripts of genes related to immune defenses, with the highest levels in continental wild boar subspecies. Overall, the loss of olfactory capacity in pigs appears to have been accompanied by reductions in the expression of candidate genes for olfaction. These changes could have resulted from unintentional selection for reduced olfactory capacity, relaxed selection for maintaining olfactory capacity, pleiotropic effects of genes under selection, or other non-selective processes. Our findings could be a cornerstone for future researches on wild boars, pigs, feral populations, and their evolutionary trajectories, aimed to provide tools to better calibrate species management as well as guidelines for breeders.

Further evidence from DNAH12 supports favorable fertility outcomes of infertile males with dynein axonemal heavy chain gene family variants

Male infertility is a major concern affecting reproductive health. Biallelic deleterious variants of most DNAH gene family members have been linked to male infertility, with intracytoplasmic sperm injection (ICSI) being an efficacious way to achieve offspring. However, the association between DNAH12 and male infertility is still limited. Here, we identified one homozygous variant and two compound heterozygous variants in DNAH12 from three infertile Chinese men. Semen analysis revealed severe asthenozoospermia, abnormal morphology, and structure of sperm flagella. Furthermore, the Dnah12 knock-out mouse revealed severe spermatogenesis failure and validated the same male infertility phenotype. Favorable fertility outcomes were achieved through ICSI in three human individuals and Dnah12 knock-out mice. Collectively, our study indicated that biallelic variants of DNAH12 can induce male infertility in both human beings and mice. Notably, evidence from DNAH12 enhanced that ICSI was an optimal intervention to achieve favorable fertility outcomes for infertile males with DNAH gene family variants.

Primary Ciliary Dyskinesia Associated Disease-Causing Variants in CCDC39 and CCDC40 Cause Axonemal Absence of Inner Dynein Arm Heavy Chains DNAH1, DNAH6, and DNAH7

Disease-causing bi-allelic DNA variants in CCDC39 and CCDC40 are frequent causes of the hereditary disorder of primary ciliary dyskinesia (PCD). The encoded proteins form a molecular ruler complex, crucial for maintaining the 96 nm repeat units along the ciliary axonemes. Defects of those proteins cause a stiff, rapid, and flickery ciliary beating pattern, recurrent respiratory infections, axonemal disorganization, and abnormal assembly of GAS8, CCDC39, and DNALI1. We performed molecular characterization of the defects in the 96 nm axonemal ruler due to disease-causing variants in CCDC39 and CCDC40 and analyzed the effect on additional axonemal components. We identified a cohort of 51 individuals with disease-causing variants in CCDC39 and CCDC40 via next-generation sequencing techniques and demonstrated that the IDA heavy chains DNAH1, DNAH6, and DNAH7 are conspicuously absent within the respiratory ciliary axonemes by immunofluorescence analyses. Hence, we show for the first time that the centrin2 (CETN2) containing IDAs are also affected. These findings underscore the crucial role of CCDC39 and CCDC40 in the assembly and function of IDAs in human respiratory cilia. Thus, our data improve the diagnostics of axonemal ruler defects by further characterizing the associated molecular IDA defects.

Infertility and pregnancy outcomes among adults with primary ciliary dyskinesia

STUDY QUESTION

What is the prevalence of infertility and ectopic pregnancies among individuals with primary ciliary dyskinesia (PCD)?

SUMMARY ANSWER

We found that 39 of 50 men (78%) and 72 of 118 women (61%) with PCD were infertile and that women with PCD had an increased risk of ectopic pregnancies (7.6 per 100 pregnancies, 95% CI 4.7-12.2).

WHAT IS KNOWN ALREADY

PCD is a heterogeneous multiorgan disease caused by mutations in genes required for the function and structure of motile cilia. Previous studies identified a link between PCD and infertility, but original data on prevalence of infertility and risk of ectopic pregnancies, the use and efficacy of medically assisted reproduction (MAR), and the association of fertility with PCD genotype are extremely limited.

STUDY DESIGN SIZE DURATION

We performed a cross-sectional survey about fertility within the Living with PCD study (formerly COVID-PCD). Living with PCD is an international, online, participatory study that collects information directly from people with PCD. People with PCD of any age from anywhere in the world can participate in the study. At the time of the survey, 482 adults with PCD were registered within the Living with PCD study.

PARTICIPANTS/MATERIALS SETTING METHODS

We sent a questionnaire on fertility on 12 July 2022, to all participants older than 18 years enrolled in the Living with PCD study. Responses were collected until 8 March 2023. The fertility questionnaire covered topics related to pregnancy attempts, use of MAR, and pregnancy outcomes. Data were collected via the Research Electronic Data Capture (REDCap) platform. We defined infertility as failure to achieve a clinical pregnancy after 12 months or use of MAR for at least one pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 265 of 482 adult participants (55%) completed the fertility questionnaire. Among 168 adults who had tried to conceive, 39 of 50 men (78%) and 72 of 118 women (61%) were infertile. Of the infertile men, 28 had tried MAR, and 17 of them (61%) fathered a child with the help of MAR. Among infertile women, 59 had used MAR, and 41 of them (69%) became pregnant with the help of MAR. In our population, women with PCD showed a relatively high risk of ectopic pregnancies: 1 in 10 women who became pregnant had at least one ectopic pregnancy and 7.6% of pregnancies were ectopic (95% CI 4.7-12.2). We evaluated the association between fertility and affected PCD genes in 46 individuals (11 men, 35 women) with available genetic and fertility information, and found differences between genotypes, e.g. all five women with a mutation in CCDC40 were infertile and all five with DNAH11 were fertile.

LIMITATIONS REASONS FOR CAUTION

The study has limitations, including potential selection bias as people experiencing problems with fertility might be more likely to fill in the questionnaire, which may have influenced our prevalence estimates. We were unable to validate clinical data obtained from participant self-reports owing to the anonymous study design, which is likely to lead to recall bias.

WIDER IMPLICATIONS OF THE FINDINGS

The study underlines the need for addressing infertility in routine PCD care, with a focus on informing individuals with PCD about their increased risk. It emphasizes the utility and efficacy of MAR in PCD-related infertility. Additionally, women attempting conception should be made aware of the increased risk of ectopic pregnancies and seek systematic early consultation to confirm an intrauterine pregnancy. Fertility, efficacy of MAR, and risk for adverse pregnancy outcomes differ between people with PCD-depending on genotypes-and close monitoring and support might be needed from fertility specialists to increase chances of successful conception.

STUDY FUNDING/COMPETING INTERESTS

Our research was funded by the Swiss National Science Foundation, Switzerland (SNSF 320030B_192804), the Swiss Lung Association, Switzerland (2021-08_Pedersen), and we also received support from the PCD Foundation, USA; the Verein Kartagener Syndrom und Primäre Ciliäre Dyskinesie, Germany; the PCD Support UK, UK; and PCD Australia, Australia. M. Goutaki received funding from the Swiss National Science Foundation, Switzerland (PZ00P3_185923). B. Maitre participates in the RaDiCo-DCP funded by INSERM France. The study authors participate in the BEAT-PCD Clinical Research Collaboration supported by the European Respiratory Society. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID NCT04602481.

The Odad3 Gene Is Necessary for Spermatozoa Development and Male Fertility in Mice

Odad3 gene loss-of-function mutation leads to Primary Ciliary Dyskinesia (PCD), a disease caused by motile cilia dysfunction. Previously, we demonstrated that knockout of the Odad3 gene in mice replicates several features of PCD, such as hydrocephalus, defects in left-right body symmetry, and male infertility, with a complete absence of sperm in the reproductive tract. The majority of Odad3 knockout animals die before sexual maturation due to severe hydrocephalus and failure to thrive, which precludes fertility studies. Here, we performed the expression analysis of the Odad3 gene during gonad development and in adult testes. We showed that Odad3 starts its expression during the first wave of spermatogenesis, specifically at the meiotic stage, and that its expression is restricted to the germ cells in the adult testes, suggesting that Odad3 plays a role in spermatozoa formation. Subsequently, we conditionally deleted the Odad3 gene in adult males and demonstrated that even partial ablation of the Odad3 gene leads to asthenoteratozoospermia with multiple morphological abnormalities of sperm flagella (MMAF) in mice. The analysis of the seminiferous tubules in Odad3-deficient mice revealed defects in spermatogenesis with accumulation of seminiferous tubules at the spermiogenesis and spermiation phases. Furthermore, analysis of fertility in heterozygous Odad3+/- knockout mice revealed a reduction in sperm count and motility as well as abnormal sperm morphology. Additionally, Odad3+/- males exhibited a shorter fertile lifespan. Overall, these results suggest the important role of Odad3 and Odad3 gene dosage in male fertility. These findings may have an impact on the genetic and fertility counseling practice of PCD patients carrying Odad3 loss-of-function mutations.

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.

Primary Ciliary Dyskinesia: A Clinical Review

Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous, motile ciliopathy, characterized by neonatal respiratory distress, recurrent upper and lower respiratory tract infections, subfertility, and laterality defects. Diagnosis relies on a combination of tests for confirmation, including nasal nitric oxide (nNO) measurements, high-speed videomicroscopy analysis (HSVMA), immunofluorescent staining, axonemal ultrastructure analysis via transmission electron microscopy (TEM), and genetic testing. Notably, there is no single gold standard confirmatory or exclusionary test. Currently, 54 causative genes involved in cilia assembly, structure, and function have been linked to PCD; this rare disease has a spectrum of clinical manifestations and emerging genotype-phenotype relationships. In this review, we provide an overview of the structure and function of motile cilia, the emerging genetics and pathophysiology of this rare disease, as well as clinical features associated with motile ciliopathies, novel diagnostic tools, and updates on genotype-phenotype relationships in PCD.

Identification of a novel MYO1D variant associated with laterality defects, congenital heart diseases, and sperm defects in humans

The establishment of left-right asymmetry is a fundamental process in animal development. Interference with this process leads to a range of disorders collectively known as laterality defects, which manifest as abnormal arrangements of visceral organs. Among patients with laterality defects, congenital heart diseases (CHD) are prevalent. Through multiple model organisms, extant research has established that myosin-Id (MYO1D) deficiency causes laterality defects. This study investigated over a hundred cases and identified a novel biallelic variant of MYO1D (NM_015194: c.1531G>A; p.D511N) in a consanguineous family with complex CHD and laterality defects. Further examination of the proband revealed asthenoteratozoospermia and shortened sperm. Afterward, the effects of the D511N variant and another known MYO1D variant (NM_015194: c.2293C>T; p.P765S) were assessed. The assessment showed that both enhance the interaction with β-actin and SPAG6. Overall, this study revealed the genetic heterogeneity of this rare disease and found that MYO1D variants are correlated with laterality defects and CHD in humans. Furthermore, this research established a connection between sperm defects and MYO1D variants. It offers guidance for exploring infertility and reproductive health concerns. The findings provide a critical basis for advancing personalized medicine and genetic counseling.

Novel SPEF2 variants cause male infertility and likely primary ciliary dyskinesia

PURPOSE

This study aimed to identify the genetic causes of male infertility and primary ciliary dyskinesia (PCD)/PCD-like phenotypes in three unrelated Han Chinese families.

METHODS

We conducted whole-exome sequencing of three patients with male infertility and PCD/PCD-like phenotypes from three unrelated Chinese families. Ultrastructural and immunostaining analyses of patient spermatozoa and respiratory cilia and in vitro analyses were performed to analyze the effects of SPEF2 variants. Intracytoplasmic sperm injection (ICSI) was administered to three affected patients.

RESULTS

We identified four novel SPEF2 variants, including one novel homozygous splicing site variant [NC_000005.10(NM_024867.4): c.4447 + 1G > A] of the SPEF2 gene in family 1, novel compound heterozygous nonsense variants [NC_000005.10(NM_024867.4): c.1339C > T (p.R447*) and NC_000005.10(NM_024867.4): c.1645G > T (p.E549*)] in family 2, and one novel homozygous missense variant [NC_000005.10(NM_024867.4): c.2524G > A (p.D842N)] in family 3. All the patients presented with male infertility and PCD/likely PCD. All variants were present at very low levels in public databases, predicted to be deleterious in silico prediction tools, and were further confirmed deleterious by in vitro analyses. Ultrastructural analyses of the spermatozoa of the patients revealed the absence of the central pair complex in the sperm flagella. Immunostaining of the spermatozoa and respiratory cilia of the patients validated the pathogenicity of the SPEF2 variants. All patients carrying SPEF2 variants underwent one ICSI cycle and delivered healthy infants.

CONCLUSION

Our study reported four novel pathogenic variants of SPEF2 in three male patients with infertility and PCD/PCD-like phenotypes, which not only extend the spectrum of SPEF2 mutations but also provide information for genetic counseling and treatment of such conditions.

Skewed X-chromosome inactivation drives the proportion of DNAAF6-defective airway motile cilia and variable expressivity in primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare airway disorder caused by defective motile cilia. Only male patients have been reported with pathogenic mutations in X-linked DNAAF6, which result in the absence of ciliary dynein arms, whereas their heterozygous mothers are supposedly healthy. Our objective was to assess the possible clinical and ciliary consequences of X-chromosome inactivation (XCI) in these mothers.

METHODS

XCI patterns of six mothers of male patients with DNAAF6-related PCD were determined by DNA-methylation studies and compared with their clinical phenotype (6/6 mothers), as well as their ciliary phenotype (4/6 mothers), as assessed by immunofluorescence and high-speed videomicroscopy analyses. The mutated X chromosome was tracked to assess the percentage of cells with a normal inactivated DNAAF6 allele.

RESULTS

The mothers' phenotypes ranged from absence of symptoms to mild/moderate or severe airway phenotypes, closely reflecting their XCI pattern. Analyses of the symptomatic mothers' airway ciliated cells revealed the coexistence of normal cells and cells with immotile cilia lacking dynein arms, whose ratio closely mirrored their XCI pattern.

CONCLUSION

This study highlights the importance of searching for heterozygous pathogenic DNAAF6 mutations in all female relatives of male PCD patients with a DNAAF6 defect, as well as in females consulting for mild chronic respiratory symptoms. Our results also demonstrate that about one-third-ranging from 20% to 50%-normal ciliated airway cells sufficed to avoid severe PCD, a result paving the way for gene therapy.

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.

Sperm hyperactivation and the CatSper channel: current understanding and future contribution of domestic animals

In female tract, mammalian sperm develop hyperactivated motility which is a key physiological event for sperm to fertilize eggs. This motility change is triggered by Ca2+ influx via the sperm-specific Ca2+ channel, CatSper. Although previous studies in human and mice largely contributed to understanding CatSper and Ca2+ signaling for sperm hyperactivation, the differences on their activation mechanisms are not well understood yet. There are several studies to examine expression and significance of the CatSper channel in non-human and non-mouse models, such as domestic animals. In this review, I summarize key knowledge for the CatSper channel from previous studies and propose future aspects for CatSper study using sperm from domestic animals.

A novel homozygous nonsense variant of AK7 is associated with multiple morphological abnormalities of the sperm flagella

RESEARCH QUESTION

Is the novel homozygous nonsense variant of AK7 associated with multiple morphological abnormalities of the sperm flagella (MMAF), a specific type of oligoasthenoteratozoospermia leading to male infertility?

DESIGN

Whole-exome sequencing and Sanger sequencing were performed to identify potential gene variants. Immunoblotting and immunofluorescence were applied to confirm the relationship between mutated genes and disease phenotypes. The concentration of reactive oxygen species and the rate of apoptosis were measured to evaluate the mitochondrial function of spermatozoa. Transmission electron microscopy and scanning electron microscopy were employed to observe sperm ultrastructure.

RESULTS

A novel homozygous nonsense variant of AK7, c.1153A>T (p. Lys385*), was identified in two infertile siblings with asthenoteratozoospermia through whole-exome sequencing. Both immunoblotting and immunofluorescence assays showed practically complete absence of AK7 in the patient's spermatozoa. Additionally, the individual with the novel AK7 variant exhibited a phenotype characterized by severe oxidative stress and apoptosis caused by mitochondrial metabolic dysfunction of spermatozoa. Notably, remarkable flagellar defects with multiple axonemes in uniflagellate spermatozoa, accompanied by mitochondrial vacuolization, were observed; this has not been reported previously in patients with other AK7 variants.

CONCLUSIONS

This study found that a novel identified homozygous nonsense variant of AK7 may be associated with MMAF-related asthenoteratozoospermia. The observed functional associations between mitochondria and sperm flagellar assembly provide evidence for potential mutual regulation between AK7 and flagella-associated proteins during spermatogenesis.

Effects of Tcte1 knockout on energy chain transportation and spermatogenesis: implications for male infertility

STUDY QUESTION

Is the Tcte1 mutation causative for male infertility?

SUMMARY ANSWER

Our collected data underline the complex and devastating effect of the single-gene mutation on the testicular molecular network, leading to male reproductive failure.

WHAT IS KNOWN ALREADY

Recent data have revealed mutations in genes related to axonemal dynein arms as causative for morphology and motility abnormalities in spermatozoa of infertile males, including dysplasia of fibrous sheath (DFS) and multiple morphological abnormalities in the sperm flagella (MMAF). The nexin-dynein regulatory complex (N-DRC) coordinates the dynein arm activity and is built from the DRC1-DRC7 proteins. DRC5 (TCTE1), one of the N-DRC elements, has already been reported as a candidate for abnormal sperm flagella beating; however, only in a restricted manner with no clear explanation of respective observations.

STUDY DESIGN SIZE DURATION

Using the CRISPR/Cas9 genome editing technique, a mouse Tcte1 gene knockout line was created on the basis of the C57Bl/6J strain. The mouse reproductive potential, semen characteristics, testicular gene expression levels, sperm ATP, and testis apoptosis level measurements were then assessed, followed by visualization of N-DRC proteins in sperm, and protein modeling in silico. Also, a pilot genomic sequencing study of samples from human infertile males (n = 248) was applied for screening of TCTE1 variants.

PARTICIPANTS/MATERIALS SETTING METHODS

To check the reproductive potential of KO mice, adult animals were crossed for delivery of three litters per caged pair, but for no longer than for 6 months, in various combinations of zygosity. All experiments were performed for wild-type (WT, control group), heterozygous Tcte1+/- and homozygous Tcte1-/- male mice. Gross anatomy was performed on testis and epididymis samples, followed by semen analysis. Sequencing of RNA (RNAseq; Illumina) was done for mice testis tissues. STRING interactions were checked for protein-protein interactions, based on changed expression levels of corresponding genes identified in the mouse testis RNAseq experiments. Immunofluorescence in situ staining was performed to detect the N-DRC complex proteins: Tcte1 (Drc5), Drc7, Fbxl13 (Drc6), and Eps8l1 (Drc3) in mouse spermatozoa. To determine the amount of ATP in spermatozoa, the luminescence level was measured. In addition, immunofluorescence in situ staining was performed to check the level of apoptosis via caspase 3 visualization on mouse testis samples. DNA from whole blood samples of infertile males (n = 137 with non-obstructive azoospermia or cryptozoospermia, n = 111 samples with a spectrum of oligoasthenoteratozoospermia, including n = 47 with asthenozoospermia) was extracted to perform genomic sequencing (WGS, WES, or Sanger). Protein prediction modeling of human-identified variants and the exon 3 structure deleted in the mouse knockout was also performed.

MAIN RESULTS AND THE ROLE OF CHANCE

No progeny at all was found for the homozygous males which were revealed to have oligoasthenoteratozoospermia, while heterozygous animals were fertile but manifested oligozoospermia, suggesting haploinsufficiency. RNA-sequencing of the testicular tissue showed the influence of Tcte1 mutations on the expression pattern of 21 genes responsible for mitochondrial ATP processing or linked with apoptosis or spermatogenesis. In Tcte1-/- males, the protein was revealed in only residual amounts in the sperm head nucleus and was not transported to the sperm flagella, as were other N-DRC components. Decreased ATP levels (2.4-fold lower) were found in the spermatozoa of homozygous mice, together with disturbed tail:midpiece ratios, leading to abnormal sperm tail beating. Casp3-positive signals (indicating apoptosis) were observed in spermatogonia only, at a similar level in all three mouse genotypes. Mutation screening of human infertile males revealed one novel and five ultra-rare heterogeneous variants (predicted as disease-causing) in 6.05% of the patients studied. Protein prediction modeling of identified variants revealed changes in the protein surface charge potential, leading to disruption in helix flexibility or its dynamics, thus suggesting disrupted interactions of TCTE1 with its binding partners located within the axoneme.

LARGE SCALE DATA

All data generated or analyzed during this study are included in this published article and its supplementary information files. RNAseq data are available in the GEO database (https://www.ncbi.nlm.nih.gov/geo/) under the accession number GSE207805. The results described in the publication are based on whole-genome or exome sequencing data which includes sensitive information in the form of patient-specific germline variants. Information regarding such variants must not be shared publicly following European Union legislation, therefore access to raw data that support the findings of this study are available from the corresponding author upon reasonable request.

LIMITATIONS REASONS FOR CAUTION

In the study, the in vitro fertilization performance of sperm from homozygous male mice was not checked.

WIDER IMPLICATIONS OF THE FINDINGS

This study contains novel and comprehensive data concerning the role of TCTE1 in male infertility. The TCTE1 gene is the next one that should be added to the 'male infertility list' because of its crucial role in spermatogenesis and proper sperm functioning.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by National Science Centre in Poland, grants no.: 2015/17/B/NZ2/01157 and 2020/37/B/NZ5/00549 (to M.K.), 2017/26/D/NZ5/00789 (to A.M.), and HD096723, GM127569-03, NIH SAP #4100085736 PA DoH (to A.N.Y.). The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Coiled-coil domain-containing 38 is required for acrosome biogenesis and fibrous sheath assembly in mice

During spermiogenesis, haploid spermatids undergo dramatic morphological changes to form slender sperm flagella and cap-like acrosomes, which are required for successful fertilization. Severe deformities in flagella cause a male infertility syndrome, multiple morphological abnormalities of the flagella (MMAF), while acrosomal hypoplasia in some cases leads to sub-optimal embryonic developmental potential. However, evidence regarding the occurrence of acrosomal hypoplasia in MMAF is limited. Here, we report the generation of base-edited mice knocked out for coiled-coil domain-containing 38 (Ccdc38) via inducing a nonsense mutation and find that the males are infertile. The Ccdc38-KO sperm display acrosomal hypoplasia and typical MMAF phenotypes. We find that the acrosomal membrane is loosely anchored to the nucleus and fibrous sheaths are disorganized in Ccdc38-KO sperm. Further analyses reveal that Ccdc38 knockout causes a decreased level of TEKT3, a protein associated with acrosome biogenesis, in testes and an aberrant distribution of TEKT3 in sperm. We finally show that intracytoplasmic sperm injection overcomes Ccdc38-related infertility. Our study thus reveals a previously unknown role for CCDC38 in acrosome biogenesis and provides additional evidence for the occurrence of acrosomal hypoplasia in MMAF.

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.

Structure and Function of Dynein's Non-Catalytic Subunits

Dynein, an ancient microtubule-based motor protein, performs diverse cellular functions in nearly all eukaryotic cells, with the exception of land plants. It has evolved into three subfamilies-cytoplasmic dynein-1, cytoplasmic dynein-2, and axonemal dyneins-each differentiated by their cellular functions. These megadalton complexes consist of multiple subunits, with the heavy chain being the largest subunit that generates motion and force along microtubules by converting the chemical energy of ATP hydrolysis into mechanical work. Beyond this catalytic core, the functionality of dynein is significantly enhanced by numerous non-catalytic subunits. These subunits are integral to the complex, contributing to its stability, regulating its enzymatic activities, targeting it to specific cellular locations, and mediating its interactions with other cofactors. The diversity of non-catalytic subunits expands dynein's cellular roles, enabling it to perform critical tasks despite the conservation of its heavy chains. In this review, we discuss recent findings and insights regarding these non-catalytic subunits.

Evaluation of The 1499T>C Variant in The AKAP3 Gene of Infertile Men with Multiple Morphological Abnormalities of The Sperm Flagella Phenotype: A Case-Control Study

BACKGROUND

Infertile men with multiple morphological abnormalities of the sperm flagella (MMAF) phenotype exhibit mosaic sperm flagella abnormalities such as short, bent, coiled, and irregular flagella or absent flagella. Sperm flagellum has an ultrastructurally axonemal structure that contains a large number of proteins. A-Kinase Anchoring Protein 3 (AKAP3) is expressed in spermatozoa. It may function as a regulator of motility and the acrosome reaction. This study aimed to compare genetic changes in infertile men suffering MMAF phenotype with the control group.

MATERIALS AND METHODS

In this case-control study, genetic variants of the AKAP3 gene were evaluated in 60 infertile men with MMAF phenotype and 40 fertile men, as control. As exon five of the AKAP3 gene encodes the functional domain of this protein, its genetic variants were studied. Therefore, polymerase chain reaction (PCR)-sequencing was undertaken on the DNA extracted from control and patients' blood samples.

RESULTS

Sixty infertile men with MMAF phenotype and 40 normozoospermic men, as control, were enrolled in this study. Four haplotype variants 1378T>C (rs10774251), 1391C>G (rs11063266), 1437T>C (rs11063265), and 1573G>A (rs1990312) were detected in all patients and controls. On the other hand, a missense mutation 1499T>C (rs12366671) was observed in four patients with the homozygous form while seven patients carried the heterozygous form. No mutation was identified in the controls (P=0.04). The difference between the variation allele frequencies was assessed in the patient and control groups by the Fisher Exact Test.

CONCLUSION

In the homozygous form, this mutation changed Isoleucine to Threonine. This alternation occurred inside the AKAP4 binding domain of the AKAP3 protein. The observed variants caused no significant deviation in the secondary structure of AKAP3 protein and probably its function in spermatozoa flagella. So, these variants cannot be considered as the causes of MMAF phenotype in the studied patients.

Fertility care among people with primary ciliary dyskinesia

INTRODUCTION

Fertility care is important for people living with primary ciliary dyskinesia (PCD) who are at increased risk of fertility problems. We investigated fertility care in an international participatory study.

METHODS

Participants of the COVID-PCD study completed an online questionnaire addressing fertility issues. We used logistic regression to study factors associated with fertility specialist visits.

RESULTS

Among 384 respondents (response rate 53%), 266 were adults (median age 44 years, interquartile range [IQR]: 33-54, 68% female), 16 adolescents, and 102 parents of children with PCD. Only half of adult participants (128; 48%) received care from fertility specialists at a median age of 30 years (IQR: 27-33)-a median of 10 years after PCD diagnosis. Only 12% were referred to fertility specialists by their PCD physician. Fertility specialist visits were reported more often by adults with pregnancy attempts (odds ratio [OR]: 9.1, 95% confidence interval [CI]: 3.8-23.6) and among people who reported fertility as important for them (OR: 5.9, 95% CI: 2.6-14.6) and less often by females (OR: 0.4, 95% CI: 0.2-0.8). Only 56% of participants who talked with healthcare professionals about fertility were satisfied with information they received. They expressed needs for more comprehensive fertility information and reported dissatisfaction with physician knowledge about PCD and fertility.

CONCLUSION

People with PCD are inconsistently referred to fertility specialists. We recommend care from fertility specialists become standard in routine PCD care, and that PCD physicians provide initial fertility information either at diagnosis or no later than transition to adult care.

Improved phenotypic classification of male infertility to promote discovery of genetic causes

An increasing number of genes are being described in the context of non-syndromic male infertility. Linking the underlying genetic causes of non-syndromic male infertility with clinical data from patients is important to establish new genotype-phenotype correlations. This process can be facilitated by using universal nomenclature, but no standardized vocabulary is available in the field of non-syndromic male infertility. The International Male Infertility Genomics Consortium aimed at filling this gap, providing a standardized vocabulary containing nomenclature based on the Human Phenotype Ontology (HPO). The "HPO tree" was substantially revised compared with the previous version and is based on the clinical work-up of infertile men, including physical examination and hormonal assessment. Some causes of male infertility can already be suspected based on the patient's clinical history, whereas in other instances, a testicular biopsy is needed for diagnosis. We assembled 49 HPO terms that are linked in a logical hierarchy and showed examples of morphological features of spermatozoa and testicular histology of infertile men with identified genetic diagnoses to describe the phenotypes. This work will help to record patients' phenotypes systematically and facilitate communication between geneticists and andrologists. Collaboration across institutions will improve the identification of patients with the same phenotypes, which will promote the discovery of novel genetic causes for non-syndromic male infertility.

Taste receptor type 1 member 3 is required for the fertility of male mice

Male infertility is a global health concern. However, its underlying pathophysiology remains unclear. Taste receptor type 1 member 3 (TAS1R3) is highly expressed in the testes, indicating its potential involvement in male fertility. Using wild-type and Tas1r3 knockout (KO) mice, we investigated whether TAS1R3 modulates male reproductive function. Tas1r3 KO mice exhibited reduced male fertility compared to WT mice, with fewer live pups per litter and a delayed first litter. Testicular transcriptome analysis indicated suppressed PKA/CREB/StAR signaling-mediated testosterone synthesis in Tas1r3 KO mice. In silico single-cell RNA sequencing revealed considerably higher Tas1r3 expression in Leydig cells than in other testicular cell subtypes. An in vitro study validated that Tas1r3 knockdown downregulated the expression of Creb1 and steroidogenic genes in Leydig cells. Our results suggest that testicular TAS1R3 is intricately involved in male reproduction via the PKA/CREB/StAR signaling pathway, highlighting its potential as a promising target for addressing male infertility.

Adverse effects of exposure to petrol-generator exhaust fumes on the reproductive hormones, testis and spermatozoa in male dogs

There is evidence that sperm count has progressively declined in men over the recent decades. Exposure to air pollutants including petrol and diesel exhaust have been reported to impair male reproduction although there is little experimental evidence. This study investigated the effects of petrol-generator exhaust fumes (PGEF) on semen, sperm, gonadal structure and hormonal status in the dog. Sixteen adult male Basenji dogs were randomly assigned four to each of 4 groups as follows: an unexposed (Control) group and three groups exposed to graded levels of PGEF for 1, 2 or 3 h per day (hpd), respectively, for 90 days. Serum concentrations of testosterone (T), follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured on days 0 (baseline), 30, 60 and 90 of the study. At day 90, semen samples were collected for semen and sperm analysis. Testicular and epididymal tissues were subjected to gross, histopathological and histomorphometric evaluation. Graded exposure to PGEF resulted in increased serum concentration of T and decreased concentrations of FSH and LH, increased seminal plasma lipid peroxidation, seminiferous and epididymal tubular degeneration, germ cell depletion, lowered sperm concentration, decreased sperm motility and vitality, and increased sperm abnormal morphology. The close proximity between dogs and humans in exposed environments underscores the importance of these findings to human reproductive health and fertility. The findings suggest that with prolonged exposure, the impairment of reproductive functions will likely play significant roles in the decline in male fertility.

LRRC23 truncation impairs radial spoke 3 head assembly and sperm motility underlying male infertility

Radial spokes (RS) are T-shaped multiprotein complexes on the axonemal microtubules. Repeated RS1, RS2, and RS3 couple the central pair to modulate ciliary and flagellar motility. Despite the cell type specificity of RS3 substructures, their molecular components remain largely unknown. Here, we report that a leucine-rich repeat-containing protein, LRRC23, is an RS3 head component essential for its head assembly and flagellar motility in mammalian spermatozoa. From infertile male patients with defective sperm motility, we identified a splice site variant of LRRC23. A mutant mouse model mimicking this variant produces a truncated LRRC23 at the C-terminus that fails to localize to the sperm tail, causing male infertility due to defective sperm motility. LRRC23 was previously proposed to be an ortholog of the RS stalk protein RSP15. However, we found that purified recombinant LRRC23 interacts with an RS head protein RSPH9, which is abolished by the C-terminal truncation. Evolutionary and structural comparison also shows that LRRC34, not LRRC23, is the RSP15 ortholog. Cryo-electron tomography clearly revealed that the absence of the RS3 head and the sperm-specific RS2-RS3 bridge structure in LRRC23 mutant spermatozoa. Our study provides new insights into the structure and function of RS3 in mammalian spermatozoa and the molecular pathogenicity of LRRC23 underlying reduced sperm motility in infertile human males.

Cilia-related diseases

More and more attention is paid to diseases such as internal transfer and brain malformation which are caused by the abnormal morphogenesis of cilia. These cilia-related diseases are divided into two categories: ciliopathy resulting from defects of primary cilia and primary ciliary dyskinesia (PCD) caused by functional dysregulation of motile cilia. Cilia are widely distributed, and their related diseases can cover many human organs and tissues. Recent studies prove that primary cilia play a key role in maintaining homeostasis in the cardiovascular system. However, molecular mechanisms of cilia-related diseases remain elusive. Here, we reviewed recent research progresses on characteristics, molecular mechanisms and treatment methods of ciliopathy and PCD. Our review is beneficial to the further research on the pathogenesis and treatment strategies of cilia-related diseases.

The role of cilia during organogenesis in zebrafish

Cilia are hair-like organelles that protrude from the surface of eukaryotic cells and are present on the surface of nearly all human cells. Cilia play a crucial role in signal transduction, organ development and tissue homeostasis. Abnormalities in the structure and function of cilia can lead to a group of human diseases known as ciliopathies. Currently, zebrafish serves as an ideal model for studying ciliary function and ciliopathies due to its relatively conserved structure and function of cilia compared to humans. In this review, we will summarize the different types of cilia that present in embryonic and adult zebrafish, and provide an overview of the advantages of using zebrafish as a vertebrate model for cilia research. We will specifically focus on the roles of cilia during zebrafish organogenesis based on recent studies. Additionally, we will highlight future prospects for ciliary research in zebrafish.

Dnali1 is required for sperm motility and male fertility in mice

BACKGROUND

The sperm flagellum is an evolutionarily conserved specialized organelle responsible for sperm motility and male fertility. Deleterious mutations in genes involved in the sperm flagellum assembly can often cause sperm motility defects and male infertility. The murine Dnali1 gene encodes a protein that is known to interact with the cytoplasmic dynein heavy chain 1.

RESULTS

A Dnali1-mutated mouse model was generated by inducing a nonsense mutation in the Dnali1 gene. The Dnali1-mutated male mice presented impaired sperm motility and were completely infertile. Although no obviously abnormal sperm morphology was observed in Dnali1-mutated male mice, the ultrastructural structure of sperm flagellum was disrupted, displaying as an asymmetrical distribution of the longitudinal columns (LCs). Notably, infertile Dnali1-mutated male mice were able to obtain offspring via ICSI.

CONCLUSIONS

Our results uncover a role of DNALI1 in sperm motility and male fertility in mice, and demonstrate that ICSI overcomes Dnali1-associated male infertility, thus providing guidance for the diagnosis and genetic counseling of DNALI1-associated human infertility.

De novo protein identification in mammalian sperm using in situ cryoelectron tomography and AlphaFold2 docking

To understand the molecular mechanisms of cellular pathways, contemporary workflows typically require multiple techniques to identify proteins, track their localization, and determine their structures in vitro. Here, we combined cellular cryoelectron tomography (cryo-ET) and AlphaFold2 modeling to address these questions and understand how mammalian sperm are built in situ. Our cellular cryo-ET and subtomogram averaging provided 6.0-Å reconstructions of axonemal microtubule structures. The well-resolved tertiary structures allowed us to unbiasedly match sperm-specific densities with 21,615 AlphaFold2-predicted protein models of the mouse proteome. We identified Tektin 5, CCDC105, and SPACA9 as novel microtubule-associated proteins. These proteins form an extensive interaction network crosslinking the lumen of axonemal doublet microtubules, suggesting their roles in modulating the mechanical properties of the filaments. Indeed, Tekt5 -/- sperm possess more deformed flagella with 180° bends. Together, our studies presented a cellular visual proteomics workflow and shed light on the in vivo functions of Tektin 5.

Defective airway intraflagellar transport underlies a combined motile and primary ciliopathy syndrome caused by IFT74 mutations

Ciliopathies are inherited disorders caused by defective cilia. Mutations affecting motile cilia usually cause the chronic muco-obstructive sinopulmonary disease primary ciliary dyskinesia (PCD) and are associated with laterality defects, while a broad spectrum of early developmental as well as degenerative syndromes arise from mutations affecting signalling of primary (non-motile) cilia. Cilia assembly and functioning requires intraflagellar transport (IFT) of cargos assisted by IFT-B and IFT-A adaptor complexes. Within IFT-B, the N-termini of partner proteins IFT74 and IFT81 govern tubulin transport to build the ciliary microtubular cytoskeleton. We detected a homozygous 3-kb intragenic IFT74 deletion removing the exon 2 initiation codon and 40 N-terminal amino acids in two affected siblings. Both had clinical features of PCD with bronchiectasis, but no laterality defects. They also had retinal dysplasia and abnormal bone growth, with a narrowed thorax and short ribs, shortened long bones and digits, and abnormal skull shape. This resembles short-rib thoracic dysplasia, a skeletal ciliopathy previously linked to IFT defects in primary cilia, not motile cilia. Ciliated nasal epithelial cells collected from affected individuals had reduced numbers of shortened motile cilia with disarranged microtubules, some misorientation of the basal feet, and disrupted cilia structural and IFT protein distributions. No full-length IFT74 was expressed, only truncated forms that were consistent with N-terminal deletion and inframe translation from downstream initiation codons. In affinity purification mass spectrometry, exon 2-deleted IFT74 initiated from the nearest inframe downstream methionine 41 still interacts as part of the IFT-B complex, but only with reduced interaction levels and not with all its usual IFT-B partners. We propose that this is a hypomorphic mutation with some residual protein function retained, which gives rise to a primary skeletal ciliopathy combined with defective motile cilia and PCD.

Dynein axonemal heavy chain 10 deficiency causes primary ciliary dyskinesia in humans and mice

Primary ciliary dyskinesia (PCD) is a congenital, motile ciliopathy with pleiotropic symptoms. Although nearly 50 causative genes have been identified, they only account for approximately 70% of definitive PCD cases. Dynein axonemal heavy chain 10 (DNAH10) encodes a subunit of the inner arm dynein heavy chain in motile cilia and sperm flagella. Based on the common axoneme structure of motile cilia and sperm flagella, DNAH10 variants are likely to cause PCD. Using exome sequencing, we identified a novel DNAH10 homozygous variant (c.589C > T, p.R197W) in a patient with PCD from a consanguineous family. The patient manifested sinusitis, bronchiectasis, situs inversus, and asthenoteratozoospermia. Immunostaining analysis showed the absence of DNAH10 and DNALI1 in the respiratory cilia, and transmission electron microscopy revealed strikingly disordered axoneme 9+2 architecture and inner dynein arm defects in the respiratory cilia and sperm flagella. Subsequently, animal models of Dnah10-knockin mice harboring missense variants and Dnah10-knockout mice recapitulated the phenotypes of PCD, including chronic respiratory infection, male infertility, and hydrocephalus. To the best of our knowledge, this study is the first to report DNAH10 deficiency related to PCD in human and mouse models, which suggests that DNAH10 recessive mutation is causative of PCD.

A rare ring chromosome 21 abnormality is associated with azoospermia in two different phenotypically normal cases

Azoospermia can be diagnosed with spermiogram analysis, and karyotyping is the golden standard to explain the etiology. In this study, we investigated two male cases with azoospermia and male infertility for chromosomal abnormalities. Their phenotypes and physical and hormonal examinations were both normal. In karyotyping G-banding and NOR staining, a rare ring chromosome 21 abnormality was detected in the cases and no microdeletion in chromosome Y. Ring abnormality, deletion size, and deleted regions were shown with subtelomeric FISH (.ish r(21)(p13q22.3?)(D21S1446-)) and array CGH analyses. Due to the findings, bioinformatics, protein, and pathway analyses were done to detect a candidate gene through common genes in two cases' deleted regions or ring chromosome 21.

IC2 participates in the cooperative activation of outer arm dynein densely attached to microtubules

Ciliary outer-arm dynein (OAD) consists of heavy chains (HCs), intermediate chains (ICs), and light chains (LCs), of which HCs are the motor proteins that produce force. Studies using the green alga Chlamydomonas have revealed that ICs and LCs form a complex (IC/LC tower) at the base of the OAD tail and play a crucial role in anchoring OAD to specific sites on the microtubule. In this study, we isolated a novel slow-swimming Chlamydomonas mutant deficient in the IC2 protein. This mutation, E279K, is in the third of the seven WD repeat domains. No apparent abnormality was observed in electron microscope observations of axonemes or in SDS-PAGE analyses of dynein subunits. To explore the reason for the lowered motility in this mutant, in vitro microtubule sliding experiments were performed, which revealed that the motor activity of the mutant OAD was lowered. In particular, a large difference was observed between wild type (WT) and the mutant in the microtubule sliding velocity in microtubule bundles formed with the addition of OAD: ~35.3 μm/sec (WT) and ~4.3 μm/sec (mutant). From this and other results, we propose that IC2 in an OAD interacts with the β HC of the adjacent OAD, and that an OAD-OAD interaction is important for efficient beating of cilia and flagella.Key words: cilia, axoneme, dynein heavy chain, cooperativity.

LRRC23 truncation impairs radial spoke 3 head assembly and sperm motility underlying male infertility

Radial spokes (RS) are T-shaped multiprotein complexes on the axonemal microtubules. Repeated RS1, RS2, and RS3 couple the central pair to modulate ciliary and flagellar motility. Despite the cell type specificity of RS3 substructures, their molecular components remain largely unknown. Here, we report that a leucine-rich repeat-containing protein, LRRC23, is an RS3 head component essential for its head assembly and flagellar motility in mammalian spermatozoa. From infertile male patients with defective sperm motility, we identified a splice site variant of LRRC23. A mutant mouse model mimicking this variant produces a truncated LRRC23 at the C-terminus that fails to localize to the sperm tail, causing male infertility due to defective sperm motility. LRRC23 was previously proposed to be an ortholog of the RS stalk protein RSP15. However, we found that purified recombinant LRRC23 interacts with an RS head protein RSPH9, which is abolished by the C-terminal truncation. Evolutionary and structural comparison also shows that LRRC34, not LRRC23, is the RSP15 ortholog. Cryo-electron tomography clearly revealed that the absence of the RS3 head and the sperm-specific RS2-RS3 bridge structure in LRRC23 mutant spermatozoa. Our study provides new insights into the structure and function of RS3 in mammalian spermatozoa and the molecular pathogenicity of LRRC23 underlying reduced sperm motility in infertile human males.

Primary ciliary dyskinesia

BACKGROUND AND OBJECTIVES

Primary ciliary dyskinesia (PCD, ORPHA:244) is a group of rare genetic disorders characterized by dysfunction of motile cilia. It is phenotypically and genetically heterogeneous, with more than 50 genes involved. Thanks to genetic, clinical, and functional characterization, immense progress has been made in the understanding and diagnosis of PCD. Nevertheless, it is underdiagnosed due to the heterogeneous phenotype and complexity of diagnosis. This review aims to help clinicians navigate this heterogeneous group of diseases. Here, we describe the broad spectrum of phenotypes associated with PCD and address pitfalls and difficult-to-interpret findings to avoid misinterpretation.

METHOD

Review of literature CONCLUSION: PCD diagnosis is complex and requires integration of history, clinical picture, imaging, functional and structural analysis of motile cilia and, if available, genetic analysis to make a definitive diagnosis. It is critical that we continue to expand our knowledge of this group of rare disorders to improve the identification of PCD patients and to develop evidence-based therapeutic approaches.

A novel frameshift mutation in DNAH6 associated with male infertility and asthenoteratozoospermia

Introduction

Asthenoteratozoospermia is one of the most common causes of male infertility. Several genes have been identified as genetic causative factors, but there is a considerable genetic heterogeneity underlying asthenoteratozoospermia. In this study, we performed a genetic analysis of two brothers from a consanguineous Uighur family in China to identify gene mutations causative for asthenoteratozoospermia-related male infertility.

Methods

Two related patients with asthenoteratozoospermia from a large consanguineous family were sequenced by whole-exome sequencing and Sanger sequencing to identify disease-causing genes. Scanning and transmission electron microscopy analysis revealed ultrastructural abnormalities of spermatozoa. Quantitative real-time PCR (qRT-PCR) analysis and immunofluorescence (IF) analysis were used to assess the expression of the mutant messenger RNA (mRNA) and protein.

Results

A novel homozygous frameshift mutation (c.2823dupT, p.Val942Cysfs*21) in DNAH6 was identified in both affected individuals and was predicted to be pathogenic. Papanicolaou staining and electron microscopy revealed multiple morphological and ultrastructural abnormalities of affected spermatozoa. qRT-PCR and IF analysis showed abnormal expression of DNAH6 in affected sperm, probably due to premature termination code and decay of abnormal 3' untranslated region (UTR) region of mRNA. Furthermore, intracytoplasmic sperm injection could achieve successful fertilization in infertile men with DNAH6 mutations.

Discussion

The novel frameshift mutation identified in DNAH6 may contribute to asthenoteratozoospermia. These findings expand the spectrum of genetic mutations and phenotypes associated with asthenoteratozoospermia and may be useful for genetic and reproductive counseling in male infertility.

Structures of sperm flagellar doublet microtubules expand the genetic spectrum of male infertility

Sperm motility is crucial for successful fertilization. Highly decorated doublet microtubules (DMTs) form the sperm tail skeleton, which propels the movement of spermatozoa. Using cryo-electron microscopy (cryo-EM) and artificial intelligence (AI)-based modeling, we determined the structures of mouse and human sperm DMTs and built an atomic model of the 48-nm repeat of the mouse sperm DMT. Our analysis revealed 47 DMT-associated proteins, including 45 microtubule inner proteins (MIPs). We identified 10 sperm-specific MIPs, including seven classes of Tektin5 in the lumen of the A tubule and FAM166 family members that bind the intra-tubulin interfaces. Interestingly, the human sperm DMT lacks some MIPs compared with the mouse sperm DMT. We also discovered variants in 10 distinct MIPs associated with a subtype of asthenozoospermia characterized by impaired sperm motility without evident morphological abnormalities. Our study highlights the conservation and tissue/species specificity of DMTs and expands the genetic spectrum of male infertility.

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.

Genome-wide association study reveals candidate markers related to field fertility and semen quality traits in Holstein-Friesian bulls

In vitro assessment of bull semen quality is routinely used in bull semen processing centres in order to ensure that semen destined to be used in the field has passed minimum standards. Despite these stringent quality control checks, individual bulls that pass the quality control checks can still vary in field fertility by up to 25%. A genome-wide association study was undertaken to determine genetic markers associated with prefreeze and post-thaw bull sperm quality traits as well as field fertility. Genome-wide association analysis was performed using a single nucleotide polymorphism (SNP) regression mixed linear model in WOMBAT. Genes within a 250 Kb span of a suggestive (P ≤ 1 × 10^-5) SNP were considered as candidate genes. One SNP was associated with adjusted pregnancy rate, and 21 SNPs were associated across the seven semen quality traits (P ≤ 1 × 10^-5). Functional candidate genes include SIPA1L2 which was associated with adjusted pregnancy rate. This encodes a Rap GTPase-activating protein involved in Rap1 signalling pathway and was previously found to play a role in the process of sperm differentiation. Gene ontology (GO) analysis also identified significantly enriched biological processes involved protein tyrosine kinase activity including genes such as DYRK1A, TEC and TXK that were associated with sperm motility prior to freezing. Another candidate gene associated with post-thaw sperm motility was FHDC1 which coordinates actin filament and microtubule dynamics. The induced 11 GO terms in the ejaculates rejected after freezing trait were related to ATPase, phosphatase and hydrolase activity. These results reveal novel specific genomic regions and candidate genes associated with economically important phenotypes such as field fertility and semen quality traits.

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.