DNAI2 mutations cause primary ciliary dyskinesia with defects in the outer dynein arm

Novel pathogenic variants of DNAH5 associated with clinical and genetic spectra of primary ciliary dyskinesia in an Arab population

Introduction: Primary ciliary dyskinesia (PCD) is caused by the dysfunction of motile cilia resulting in insufficient mucociliary clearance of the lungs. This study aimed to map novel PCD variants and determine their pathogenicity in PCD patients in Kuwait. Methods: Herein, we present five PCD individuals belonging to a cohort of 105 PCD individuals recruited from different hospitals in Kuwait. Genomic DNAs from the family members were analysed to screen for pathogenic PCD variants. Transmission electron microscopy (TEM) and immunofluorescence (IF) analyses were performed on the nasal biopsies to detect specific structural abnormalities within the ciliated cells. Results: Genetic screening and functional analyses confirmed that the five PCD individuals carried novel pathogenic variants of DNAH5 causing PCD in three Arabic families. Of these, one multiplex family with two affected individuals showed two novel homozygous missense variants in DNAH5 causing PCD with situs inversus; another multiplex family with two affected individuals showed two newly identified compound heterozygous variants in DNAH5 causing PCD with situs solitus. In addition, novel heterozygous variants were identified in a child with PCD and situs solitus from a singleton family with unrelated parents. TEM analysis demonstrated the lack of outer dynein arms (ODAs) in all analysed samples, and IF analysis confirmed the absence of the dynein arm component of DNAH5 from the ciliary axoneme. Conclusion: The newly identified pathogenic variants of DNAH5 are associated with PCD as well as variable pulmonary clinical manifestations in Arabic families.

Three cases of sperm immobility for intracytoplasmic sperm injection using testicular sperm

Introduction

Sperm immobility is a condition in which sperm are viable but not motile. We reported three patients with sperm immobility, who underwent testicular sperm extraction-intracytoplasmic sperm injection.

Case presentation

In case 1, a 32-year-old patient with sperm immobility had previously undergone intracytoplasmic sperm injection with ejaculated sperm; however, pregnancy was unsuccessful. testicular sperm extraction-intracytoplasmic sperm injection was performed at our clinic, and pregnancy was achieved. In case 2, a 23-year-old patient with clinical varicocele whose semen analysis revealed sperm immobility underwent varicocelectomy, without improvement. Using the hypo-osmotic swelling test technique, testicular sperm extraction-intracytoplasmic sperm injection was performed; however, pregnancy was not achieved. In case 3, a 44-year-old patient with sperm immobility underwent testicular sperm extraction, and motile sperm were retrieved. testicular sperm extraction-intracytoplasmic sperm injection using these sperm resulted in pregnancy.

Conclusion

Although testicular sperm extraction-intracytoplasmic sperm injection is not considered a solution in patients with sperm immobility, pregnancies were achieved. testicular sperm extraction-intracytoplasmic sperm injection may be successful in some cases in which ejaculated sperm intracytoplasmic sperm injection is unsuitable.

PTEN decreases NR2F1 expression to inhibit ciliogenesis during EGFRL858R-induced lung cancer progression

Lung cancer is the major cause of death worldwide. Activation of oncogenes or inhibition of tumor suppressors causes cancer formation. Previous studies have indicated that PTEN, as a tumor suppressor, inhibits cancer formation. In this study, we studied the role of PTEN in EGFRL858R-induced lung cancer in vivo. Interestingly, loss of PTEN increased bronchial cell hyperplasia but decreased alveolar cell hyperplasia in EGFRL858R*PTEN-/--induced lung cancer. Systematic analysis of gene expression by RNA-seq showed that several genes related to ciliogenesis were upregulated in EGFRL858R*PTEN-/--induced lung cancer and subsequently showed that bronchial ciliated cells were hyperplastic. Several critical ciliogenesis-related genes, such as Mucin5A, DNAI2, and DNAI3, were found to be regulated by NR2F1. Next, NR2F1 was found to be inhibited by overexpression of PTEN, indicating that PTEN negatively regulates NR2F1, thereby inhibiting the expression of ciliogenesis-related genes and leading to the inhibition of bronchial cell hyperplasia during EGFRL858R-induced lung cancer progression. In addition, we also found that PTEN decreased AKT phosphorylation in A549, KRAS mutant, and H1299 cells but increased AKT phosphorylation in PC9, EGFRL858R, and H1299L858R cells, suggesting that PTEN may function as a tumor suppressor and an oncogene in lung cancers with KRAS mutation and EGFR mutation, respectively. PTEN acts as a double-edged sword that differentially regulates EGFRL858R-induced lung cancer progression in different genomic backgrounds. Understanding the PTEN in lung cancer with different genetic backgrounds will be beneficial for therapy in the future.

5- methylcytidine effectively improves spermatogenesis recovery in busulfan-induced oligoasthenospermia mice

The function and regulatory mechanisms of 5-methylcytidine (m5C) in oligoasthenospermia remain unclear. In this study, we made a mouse model of oligoasthenospermia through the administration of busulfan (BUS). For the first time, we demonstrated that m5C levels decreased in oligoasthenospermia. The m5C levels were upregulated through the treatments of 5-methylcytidine. The testicular morphology and sperm concentrations were improved via upregulating m5C. The cytoskeletal regenerations of testis and sperm were accompanying with m5C treatments. m5C treatments improved T levels and reduced FSH and LH levels. The levels of ROS and MDA were significantly reduced through m5C treatments. RNA sequencing analysis showed m5C treatments increased the expression of genes involved in spermatid differentiation/development and cilium movement. Immunofluorescent staining demonstrated the regeneration of cilium and quantitative PCR (qPCR) confirmed the high expression of genes involved in spermatogenesis. Collectively, our findings suggest that the upregulation of m5C in oligoasthenospermia facilitates testicular morphology recovery and male infertility via multiple pathways, including cytoskeletal regeneration, hormonal levels, attenuating oxidative stress, spermatid differentiation/development and cilium movement. m5C may be a potential therapeutic agent for oligoasthenospermia.

Absolute quantitation of human wild-type DNAI1 protein in lung tissue using a nanoLC-PRM-MS-based targeted proteomics approach coupled with immunoprecipitation

BACKGROUND

Dynein axonemal intermediate chain 1 protein (DNAI1) plays an essential role in cilia structure and function, while its mutations lead to primary ciliary dyskinesia (PCD). Accurate quantitation of DNAI1 in lung tissue is crucial for comprehensive understanding of its involvement in PCD, as well as for developing the potential PCD therapies. However, the current protein quantitation method is not sensitive enough to detect the endogenous level of DNAI1 in complex biological matrix such as lung tissue.

METHODS

In this study, a quantitative method combining immunoprecipitation with nanoLC-MS/MS was developed to measure the expression level of human wild-type (WT) DNAI1 protein in lung tissue. To our understanding, it is the first immunoprecipitation (IP)-MS based method for absolute quantitation of DNAI1 protein in lung tissue. The DNAI1 quantitation was achieved through constructing a standard curve with recombinant human WT DNAI1 protein spiked into lung tissue matrix.

RESULTS

This method was qualified with high sensitivity and accuracy. The lower limit of quantitation of human DNAI1 was 4 pg/mg tissue. This assay was successfully applied to determine the endogenous level of WT DNAI1 in human lung tissue.

CONCLUSIONS

The results clearly demonstrate that the developed assay can accurately quantitate low-abundance WT DNAI1 protein in human lung tissue with high sensitivity, indicating its high potential use in the drug development for DNAI1 mutation-caused PCD therapy.

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.

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.

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).

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.

Pathogenic variants in CLXN encoding the outer dynein arm docking-associated calcium-binding protein calaxin cause primary ciliary dyskinesia

PURPOSE

Primary ciliary dyskinesia (PCD) is a heterogeneous disorder that includes respiratory symptoms, laterality defects, and infertility caused by dysfunction of motile cilia. Most PCD-causing variants result in abnormal outer dynein arms (ODAs), which provide the generative force for respiratory ciliary beating and proper mucociliary clearance.

METHODS

In addition to studies in mouse and planaria, clinical exome sequencing and functional analyses in human were performed.

RESULTS

In this study, we identified homozygous pathogenic variants in CLXN (EFCAB1/ODAD5) in 3 individuals with laterality defects and respiratory symptoms. Consistently, we found that Clxn is expressed in mice left-right organizer. Transmission electron microscopy depicted ODA defects in distal ciliary axonemes. Immunofluorescence microscopy revealed absence of CLXN from the ciliary axonemes, absence of the ODA components DNAH5, DNAI1, and DNAI2 from the distal axonemes, and mislocalization or absence of DNAH9. In addition, CLXN was undetectable in ciliary axonemes of individuals with defects in the ODA-docking machinery: ODAD1, ODAD2, ODAD3, and ODAD4. Furthermore, SMED-EFCAB1-deficient planaria displayed ciliary dysmotility.

CONCLUSION

Our results revealed that pathogenic variants in CLXN cause PCD with defects in the assembly of distal ODAs in the respiratory cilia. CLXN should be referred to as ODA-docking complex-associated protein ODAD5.

Ccdc57 is required for straightening the body axis by regulating ciliary motility in the brain ventricle of zebrafish

Recently, cilia defects have been proposed to contribute to scoliosis. Here, we demonstrate that coiled-coil domain-containing 57 (Ccdc57) plays an essential role in straightening the body axis of zebrafish by regulating ciliary beating in the brain ventricle (BV). Zygotic ccdc57 (Zccdc57) mutant zebrafish developes scoliosis without significant changes in their bone density and calcification, and the maternal-zygotic ccdc57 (MZccdc57) mutant embryos display curved bodies since the long-pec stage. The expression of ccdc57 is enriched in ciliated tissues and immunofluorescence analysis reveals colocalization of Ccdc57-HA with acetylated α-tubulin, implicating it in having a role in ciliary function. Further examination reveals that it is the coordinated cilia beating of multiple cilia bundles (MCB) in the MZccdc57 mutant embryos that is affected at 48 hours post fertilization, when the compromised cerebrospinal fluid flow and curved body axis have already occurred. Either ccdc57 mRNA injection or epinephrine treatment reverses the spinal curvature in MZccdc57 mutant larvae from ventrally curly to straight or even dorsally curly and significantly upregulates urotensin signaling. This study reveals the role of ccdc57 in maintaining coordinated cilia beating of MCB in the BV.

Kif9 is an active kinesin motor required for ciliary beating and proximodistal patterning of motile axonemes

Most motile cilia have a stereotyped structure of nine microtubule outer doublets and a single central pair of microtubules. The central pair of microtubules are surrounded by a set of proteins, termed the central pair apparatus. A specific kinesin, Klp1 projects from the central pair and contributes to ciliary motility in Chlamydomonas. The vertebrate ortholog, Kif9, is required for beating in mouse sperm flagella, but the mechanism of Kif9/Klp1 function remains poorly defined. Here, using Xenopus epidermal multiciliated cells, we show that Kif9 is necessary for ciliary motility and the proper distal localization of not only central pair proteins, but also radial spokes and dynein arms. In addition, single-molecule assays in vitro reveal that Xenopus Kif9 is a long-range processive motor, although it does not mediate long-range movement in ciliary axonemes in vivo. Together, our data suggest that Kif9 is integral for ciliary beating and is necessary for proper axonemal distal end integrity.

Schmidtea mediterranea as a Model Organism to Study the Molecular Background of Human Motile Ciliopathies

Cilia and flagella are evolutionarily conserved organelles that form protrusions on the surface of many growth-arrested or differentiated eukaryotic cells. Due to the structural and functional differences, cilia can be roughly classified as motile and non-motile (primary). Genetically determined dysfunction of motile cilia is the basis of primary ciliary dyskinesia (PCD), a heterogeneous ciliopathy affecting respiratory airways, fertility, and laterality. In the face of the still incomplete knowledge of PCD genetics and phenotype-genotype relations in PCD and the spectrum of PCD-like diseases, a continuous search for new causative genes is required. The use of model organisms has been a great part of the advances in understanding molecular mechanisms and the genetic basis of human diseases; the PCD spectrum is not different in this respect. The planarian model (Schmidtea mediterranea) has been intensely used to study regeneration processes, and-in the context of cilia-their evolution, assembly, and role in cell signaling. However, relatively little attention has been paid to the use of this simple and accessible model for studying the genetics of PCD and related diseases. The recent rapid development of the available planarian databases with detailed genomic and functional annotations prompted us to review the potential of the S. mediterranea model for studying human motile ciliopathies.

DNALI1 deficiency causes male infertility with severe asthenozoospermia in humans and mice by disrupting the assembly of the flagellar inner dynein arms and fibrous sheath

The axonemal dynein arms (outer (ODA) and inner dynein arms (IDAs)) are multiprotein structures organized by light, intermediate, light intermediate (LIC), and heavy chain proteins. They hydrolyze ATP to promote ciliary and flagellar movement. Till now, a variety of dynein protein deficiencies have been linked with asthenospermia (ASZ), highlighting the significance of these structures in human sperm motility. Herein, we detected bi-allelic DNALI1 mutations [c.663_666del (p.Glu221fs)], in an ASZ patient, which resulted in the complete loss of the DNALI1 in the patient's sperm. We identified loss of sperm DNAH1 and DNAH7 rather than DNAH10 in both DNALI1^663_666del patient and Dnali1^-/- mice, demonstrating that mammalian DNALI1 is a LIC protein of a partial IDA subspecies. More importantly, we revealed that DNALI1 loss contributed to asymmetries in the most fibrous sheath (FS) of the sperm flagellum in both species. Immunoprecipitation revealed that DNALI1 might interact with the cytoplasmic dynein complex proteins in the testes. Furthermore, DNALI1 loss severely disrupted the transport and assembly of the FS proteins, especially AKAP3 and AKAP4, during flagellogenesis. Hence, DNALI1 may possess a non-classical molecular function, whereby it regulates the cytoplasmic dynein complex that assembles the flagella. We conclude that a DNALI deficiency-induced IDAs injury and an asymmetric FS-driven tail rigid structure alteration may simultaneously cause flagellum immotility. Finally, intracytoplasmic sperm injection (ICSI) can effectively resolve patient infertility. Collectively, we demonstrate that DNALI1 is a newly causative gene for AZS in both humans and mice, which possesses multiple crucial roles in modulating flagellar assembly and motility.

Loss-of-function mutations in CFAP57 cause multiple morphological abnormalities of the flagella in humans and mice

Multiple morphological abnormalities of the sperm flagella (MMAF) are the most severe form of asthenozoospermia due to impaired axoneme structure in sperm flagella. Dynein arms are necessary components of the sperm flagellar axoneme. In this study, we recruited 3 unrelated consanguineous Pakistani families with multiple MMAF-affected individuals, who had no overt ciliary symptoms. Whole-exome sequencing and Sanger sequencing identified 2 cilia and flagella associated protein 57 (CFAP57) loss-of-function mutations (c.2872C>T, p. R958*; and c.2737C>T, p. R913*) recessively segregating with male infertility. A mouse model mimicking the mutation (c.2872C>T) was generated and recapitulated the typical MMAF phenotype of CFAP57-mutated individuals. Both CFAP57 mutations caused loss of the long transcript-encoded CFAP57 protein in spermatozoa from MMAF-affected individuals or from the Cfap57-mutant mouse model while the short transcript was not affected. Subsequent examinations of the spermatozoa from Cfap57-mutant mice revealed that CFAP57 deficiency disrupted the inner dynein arm (IDA) assembly in sperm flagella and that single-headed IDAs were more likely to be affected. Thus, our study identified 2 pathogenic mutations in CFAP57 in MMAF-affected individuals and reported a conserved and pivotal role for the long transcript-encoded CFAP57 in IDAs' assembly and male fertility.

miRNA Profiling of Major Testicular Germ Cells Identifies Stage-Specific Regulators of Spermatogenesis

Spermatogenesis is tightly controlled at transcriptional, post-transcriptional, and epigenetic levels by various regulators, including miRNAs. This study deals with the identification of miRNAs critical to the three important stages of germ cell development (spermatocytes, round spermatids, and mature sperm) during spermatogenesis. We used high-throughput transcriptome sequencing to identify the differentially expressed miRNAs in the pachytene spermatocytes, round spermatids, and mature sperm of rat. We identified 1843 miRNAs that were differentially expressed across the three stages of germ cell development. These miRNAs were further categorized into three classes according to their pattern of expression during spermatogenesis: class 1 - miRNAs found exclusively in one stage and absent in the other two stages; class 2 - miRNAs found in any two stages but absent in the third stage; class 3 - miRNAs expressed in all the three stages. Six hundred forty-six miRNAs were found to be specific to one developmental stage, 443 miRNAs were found to be common across any two stages, and 754 miRNAs were common to all the three stages. Target prediction for ten most abundant miRNAs specific to each category identified miRNA regulators of mitosis, meiosis, and cell differentiation. The expression of each miRNA is specific to a particular developmental stage, which is required to maintain a significant repertoire of target mRNAs in the respective stage. Thus, this study provided valuable data that can be used in the future to identify the miRNAs involved in spermatogenic arrest at a particular stage of the germ cell development.

Identification of a novel founder variant in DNAI2 cause primary ciliary dyskinesia in five consanguineous families derived from a single tribe descendant of Arabian Peninsula

Introduction: Primary ciliary dyskinesia (PCD) is caused by dysfunction of motile cilia resulting in insufficient mucociliary clearance of the lungs. The overall aim of this study is to identify disease causing genetic variants for PCD patients in the Kuwaiti population.

Methods: A cohort of multiple consanguineous PCD families was identified from Kuwaiti patients and genomic DNA from the family members was analysed for variant screening. Transmission electron microscopy (TEM) and immunofluorescent (IF) analyses were performed on nasal brushings to detect specific structural abnormalities within ciliated cells.

Results: All the patients inherited the same founder variant in DNAI2 and exhibited PCD symptoms. TEM analysis demonstrated lack of outer dynein arms (ODA) in all analysed samples. IF analysis confirmed absence of DNAI1, DNAI2, and DNAH5 from the ciliary axoneme. Whole exome sequencing, autozygosity mapping and segregation analysis confirmed that seven patients carry the same homozygous missense variant (DNAI2:c.740G>A; p.Arg247Gln; rs755060592).

Conclusion:DNAI2:c.740G>A is the founder variant causing PCD in patients belonging to a particular Arabian tribe which practices consanguineous marriages.

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.

Ependymal Cilia: Physiology and Role in Hydrocephalus

Cerebrospinal fluid (CSF), a colorless liquid that generally circulates from the lateral ventricles to the third and fourth ventricles, provides essential nutrients for brain homeostasis and growth factors during development. As evidenced by an increasing corpus of research, CSF serves a range of important functions. While it is considered that decreased CSF flow is associated to the development of hydrocephalus, it has recently been postulated that motile cilia, which line the apical surfaces of ependymal cells (ECs), play a role in stimulating CSF circulation by cilia beating. Ependymal cilia protrude from ECs, and their synchronous pulsing transports CSF from the lateral ventricle to the third and fourth ventricles, and then to the subarachnoid cavity for absorption. As a result, we postulated that malfunctioning ependymal cilia could disrupt normal CSF flow, raising the risk of hydrocephalus. This review aims to demonstrate the physiological functions of ependymal cilia, as well as how cilia immobility or disorientation causes problems. We also conclude conceivable ways of treatment of hydrocephalus currently for clinical application and provide theoretical support for regimen improvements by investigating the relationship between ependymal cilia and hydrocephalus development.

Dnah9 mutant mice and organoid models recapitulate the clinical features of patients with PCD and provide an excellent platform for drug screening

Primary cilia dyskinesia (PCD) is a rare genetic disease caused by ciliary structural or functional defects. It causes severe outcomes in patients, including recurrent upper and lower airway infections, progressive lung failure, and randomization of heterotaxy. To date, although 50 genes have been shown to be responsible for PCD, the etiology remains elusive. Meanwhile, owing to the lack of a model mimicking the pathogenesis that can be used as a drug screening platform, thereby slowing the development of related therapies. In the current study, we identified compound mutation of DNAH9 in a patient with PCD with the following clinical features: recurrent respiratory tract infections, low lung function, and ultrastructural defects of the outer dynein arms (ODAs). Bioinformatic analysis, structure simulation assay, and western blot analysis showed that the mutations affected the structure and expression of DNAH9 protein. Dnah9 knock-down (KD) mice recapitulated the patient phenotypes, including low lung function, mucin accumulation, and increased immune cell infiltration. Immunostaining, western blot, and co-immunoprecipitation analyses were performed to clarify that DNAH9 interacted with CCDC114/GAS8 and diminished their protein levels. Furthermore, we constructed an airway organoid of Dnah9 KD mice and discovered that it could mimic the key features of the PCD phenotypes. We then used organoid as a drug screening model to identify mitochondrial-targeting drugs that can partially elevate cilia beating in Dnah9 KD organoid. Collectively, our results demonstrated that Dnah9 KD mice and an organoid model can recapture the clinical features of patients with PCD and provide an excellent drug screening platform for human ciliopathies.

Spectrum of Genetic Variants in a Cohort of 37 Laterality Defect Cases

Laterality defects are defined by the perturbed left–right arrangement of organs in the body, occurring in a syndromal or isolated fashion. In humans, primary ciliary dyskinesia (PCD) is a frequent underlying condition of defective left–right patterning, where ciliary motility defects also result in reduced airway clearance, frequent respiratory infections, and infertility. Non-motile cilia dysfunction and dysfunction of non-ciliary genes can also result in disturbances of the left–right body axis. Despite long-lasting genetic research, identification of gene mutations responsible for left–right patterning has remained surprisingly low. Here, we used whole-exome sequencing with Copy Number Variation (CNV) analysis to delineate the underlying molecular cause in 35 mainly consanguineous families with laterality defects. We identified causative gene variants in 14 families with a majority of mutations detected in genes previously associated with PCD, including two small homozygous CNVs. None of the patients were previously clinically diagnosed with PCD, underlining the importance of genetic diagnostics for PCD diagnosis and adequate clinical management. Identified variants in non-PCD-associated genes included variants in PKD1L1 and PIFO, suggesting that dysfunction of these genes results in laterality defects in humans. Furthermore, we detected candidate variants in GJA1 and ACVR2B possibly associated with situs inversus. The low mutation detection rate of this study, in line with other previously published studies, points toward the possibility of non-coding genetic variants, putative genetic mosaicism, epigenetic, or environmental effects promoting laterality defects.

Syndromic male subfertility: a network view of genome-phenome associations

Background

Male infertility is a disorder of the reproductive system with a highly complex genetic landscape. In most cases, the reason for male infertility remains unknown; however, the importance of genetic abnormalities in the diagnosis of subfertility/infertility is becoming increasingly recognized. Several syndromes include impaired male fertility in the clinical picture, although a comprehensive analysis of genetic causes of the syndromology perspective of male reproduction is not yet available.

Objectives

(1) To develop a catalog of syndromes and corresponding genes associated with impaired male fertility and (2) to visualize an up‐to‐date genome–phenome network of syndromic male subfertility.

Materials and methods

Published literature was retrieved from the Online Mendelian Inheritance in Man, Orphanet, Human Phenotype Ontology and PubMed databases using keywords “male infertility,” “syndrome,” “gene,” and “case report”; time period from 1980 to September, 2021. Retrieved data were organized as a catalog and complemented with identification numbers of syndromes (MIM ID) and genes (Gene ID). The genome–phenome network and the phenome network were visualized using Cytoscape and Gephi software platforms. Protein–protein interaction analysis was performed using STRING tool.

Results

Retrieved syndromes were presented as (1) a catalog containing 63 syndromes and 93 associated genes, (2) a genome–phenome network including CHD7 and WT1 genes and Noonan and Kartagener syndromes, and (3) a phenome network including 63 syndromes, and 25 categories of clinical features.

Discussion

The developed catalog will contribute to the advances and translational impact toward understanding the factors of syndromic male infertility. Visualized networks provide simple, flexible tools for clinicians and researchers to quickly generate hypotheses and gain a deeper understanding of underlying mechanisms affecting male reproduction.

Conclusion

Recognition of the significance of genome–phenome visualization as part of network medicine can help expedite efforts toward unravelling molecular mechanisms and enable advances personal/precision medicine of male reproduction and other complex traits.

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.

Whole-exome sequencing of a cohort of infertile men reveals novel causative genes in teratozoospermia that are chiefly related to sperm head defects

STUDY QUESTION

Can whole-exome sequencing (WES) and in vitro validation studies identify new causative genes associated with teratozoospermia, particularly for sperm head defect?

SUMMARY ANSWER

We investigated a core group of infertile patients, including 82 cases with unexplained abnormal sperm head and 67 individuals with multiple morphological abnormalities of the sperm flagella (MMAF), and revealed rare and novel deleterious gene variants correlated with morphological abnormalities of the sperm head or tail defects.

WHAT IS KNOWN ALREADY

Teratozoospermia is one of the most common factors causing male infertility. Owing to high phenotypic variability, currently known genetic causes of teratozoospermia can only explain a rather minor component for patients with anomalous sperm-head shapes, and the agents responsible for atypical sperm head shapes remain largely unknown.

STUDY DESIGN, SIZE, DURATION

We executed WES analysis of a Chinese cohort of patients (N = 149) with teratozoospermia to identify novel genetic causes particularly for defective sperm head. We also sought to reveal the influence of different abnormalities of sperm morphology on ICSI outcome.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In this study, a cohort of 149 infertile men (82 with abnormal sperm head and 67 with MMAF) were recruited. We implemented WES on infertile patients and analyzed the negative effects of the mutations of candidate genes on their protein conformations and/or expression. We also investigated the candidate genes' spatiotemporal expression/localization during spermatogenesis in both humans and mice, and explored their interactions with proteins that are known to be involved in sperm development. We also compared the ICSI outcomes of the affected individuals with various aberrations in sperm morphology.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified rare and deleterious variants of piwi like RNA-mediated gene silencing 4 (PIWIL4: 1/82 patients, 1.21%), coiled-coil and C2 domain containing 1B (CC2D1B: 1/82 patients, 1.21%), cyclin B3 (CCNB3: 1/82 patients, 1.21%), KIAA1210 (KIAA1210: 2/82 patients, 2.43%) and choline phosphotransferase 1 (CHPT1: 1/82 patients, 1.21%), which are novel correlates of morphological abnormalities of the sperm head; functional evidence supports roles for all of these genes in sperm head formation. The mutations of septin 12 (SEPTIN12: 2/82 patients, 2.43%) are suggested to be associated with acrosome defects. We additionally observed novel causative mutations of dynein axonemal heavy chain 2 (DNAH2: 1/67 patients, 1.49%), dynein axonemal heavy chain 10 (DNAH10: 1/67 patients, 1.49%) and dynein axonemal heavy chain 12 (DNAH12: 1/67 patients, 1.49%) in patients with MMAF, and revealed a significantly lower fertilization rate of the abnormal sperm-head group compared to the MMAF group following ICSI. Consequently, our study also suggests that the mutations of PIWIL4 and CC2D1B might be circumvented by ICSI to a degree, and that CHPT1 and KIAA1210 loss-of-function variants might be associated with failed ICSI treatment.

LIMITATIONS, REASONS FOR CAUTION

In this study, we discovered the relationship between the genotype and phenotype of the novel causative genes of sperm head deformities in humans. However, the molecular mechanism of the relevant genes involved in sperm head development needs to be further illuminated in future research. Furthermore, evidence should be provided using knockout/knock-in mouse models for additional confirmation of the roles of these novel genes in spermatogenesis.

WIDER IMPLICATIONS OF THE FINDINGS

This cohort study of 149 Chinese infertile men documents novel genetic factors involved in teratozoospermia, particularly in anomalous sperm head formation. For the first time, we suggest that SEPTIN12 is related to human acrosomal hypoplasia, and that CCNB3 is a novel causative gene for globozoospermia in humans. We also uncovered variants in two genes-KIAA1210 and CHPT1associated with acrosomal biogenesis in patients with small or absent acrosomes. Additionally, it is postulated that loss-of-function mutations of PIWIL4 and CC2D1B have a contribution to the abnormal sperm-head formation. Furthermore, we are first to demonstrate the influence of different sperm morphologies on ICSI outcomes and indicates that the abnormal sperm head may play a significant role in fertilization failure. Our findings therefore provide valuable information for the diagnosis of teratozoospermia, particularly with respect to abnormalities of the sperm head. This will allow clinicians to adopt the optimal treatment strategy and to develop personalized medicine directly targeting these effects.

STUDY FUNDING/COMPETING INTEREST(S)

This work was financed by the West China Second University Hospital of Sichuan University (KS369 and KL042). The authors declare that they do not have any conflicts of interests.

TRIAL REGISTRATION NUMBER

N/A.

Bi-allelic mutations in DNAH7 cause asthenozoospermia by impairing the integrality of axoneme structure

Asthenozoospermia is the most common cause of male infertility. Dynein protein arms play a crucial role in the motility of both the cilia and flagella, and defects in these proteins generally impair the axoneme structure and cause primary ciliary dyskinesia. But relatively little is known about the influence of dynein protein arm defects on sperm flagella function. Here, we recruited 85 infertile patients with idiopathic asthenozoospermia and identified bi-allelic mutations in DNAH7 (NM_018897.3) from three patients using whole-exome sequencing. These variants are rare, highly pathogenic, and very conserved. The spermatozoa from the patients with DNAH7 bi-allelic mutations showed specific losses in the inner dynein arms. The expression of DNAH7 in the spermatozoa from the DNAH7-defective patients was significantly decreased, but these patients were able to have their children via intra-cytoplasmic sperm injection treatment. Our study is the first to demonstrate that bi-allelic mutations in DNAH7 may impair the integrality of axoneme structure, affect sperm motility, and cause asthenozoospermia in humans. These findings may extend the spectrum of etiological genes and provide new clues for the diagnosis and treatment of patients with asthenozoospermia.

Nucleo-cytoplasmic shuttling of splicing factor SRSF1 is required for development and cilia function

Shuttling RNA-binding proteins coordinate nuclear and cytoplasmic steps of gene expression. The SR family proteins regulate RNA splicing in the nucleus and a subset of them, including SRSF1, shuttles between the nucleus and cytoplasm affecting post-splicing processes. However, the physiological significance of this remains unclear. Here, we used genome editing to knock-in a nuclear retention signal (NRS) in Srsf1 to create a mouse model harboring an SRSF1 protein that is retained exclusively in the nucleus. Srsf1NRS/NRS mutants displayed small body size, hydrocephalus, and immotile sperm, all traits associated with ciliary defects. We observed reduced translation of a subset of mRNAs and decreased abundance of proteins involved in multiciliogenesis, with disruption of ciliary ultrastructure and motility in cells and tissues derived from this mouse model. These results demonstrate that SRSF1 shuttling is used to reprogram gene expression networks in the context of high cellular demands, as observed here, during motile ciliogenesis.

Emerging Genotype-Phenotype Relationships in Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a rare inherited condition affecting motile cilia and leading to organ laterality defects, recurrent sino-pulmonary infections, bronchiectasis, and severe lung disease. Research over the past twenty years has revealed variability in clinical presentations, ranging from mild to more severe phenotypes. Genotype and phenotype relationships have emerged. The increasing availability of genetic panels for PCD continue to redefine these genotype-phenotype relationships and reveal milder forms of disease that had previously gone unrecognized.

[Dyspnea and situs inversus in a boy aged 3 days]

A boy was admitted on day 3 after birth due to shortness of breath for 2 days and cyanosis for 1 day. He had clinical manifestations of dyspnea in the early postnatal period and situs inversus, and was finally diagnosed with Kartagener syndrome. His condition was improved after oxygen therapy, anti-infective therapy, and aerosol therapy. The genetic testing showed that there was a large-fragment loss of heterozygosity, exon 48_50, and a hemizygous mutation, c.7915C > T(p.R2639X), in the DNAH5 gene. Kartagener syndrome is a rare autosomal recessive disease, and this is the first case of Kartagener syndrome diagnosed in the neonatal period in China.

CCDC114, DNAI2 and TOP2A involves in the effects of tibolone treatment on postmenopausal endometrium

BACKGROUND

This study aimed to explore the molecular mechanisms of tibolone treatment in postmenopausal women.

METHODS

The gene set enrichment profile, GSE12446, which includes 9 human endometrial samples from postmenopausal women treated with tibolone (tibolone group) and 9 control samples (control group), was downloaded from GEO database for analysis. Differentially expressed genes (DEGs) in tibolone vs. control groups were identified and then used for function and pathway enrichment analysis. Protein-protein interaction (PPI) network and module analyses were also performed. Finally, drug-target interaction was predicted for genes in modules, and then were validated in Pubmed.

RESULTS

A total of 238 up-regulated DEGs and 72 down-regulated DEGs were identified. These DEGs were mainly enriched in various biological processed and pathways, such as cilium movement (e.g., CCDC114 and DNAI2), calcium ion homeostasis, regulation of hormone levels and complement/coagulation cascades. PPI network contained 368 interactions and 166 genes, of which IGF1, DNALI1, CCDC114, TOP2A, DNAH5 and DNAI2 were the hue genes. A total of 96 drug-gene interactions were obtained, including 94 drugs and eight genes. TOP2A and HTR2B were found to be targets of 28 drugs and 38 drugs, respectively. Among the 94 obtained drugs, only 12 drugs were reported in studies, of which 7 drugs (e.g., epirubicin) were found to target TOP2A.

CONCLUSIONS

CCDC114 and DNAI2 might play important roles in tibolone-treated postmenopausal women via cilium movement function. TOP2A might be a crucial target of tibolone in endometrium of postmenopausal women.

Whole-exome sequencing reveals a combination of extremely rare single-nucleotide polymorphism of DNAH9 and RSPH1 genes in a Japanese fetus with situs viscerum inversus

Randomization of left-right body asymmetry, situs viscerum inversus (heterotaxy), is commonly associated with primary ciliary dyskinesia (PCD) resulting from an abnormal ciliary structure, with approximately 50% of PCD patients exhibiting organ laterality defects. I herein report an intrauterine fetal death case, in which an autopsy revealed two lobes of the bilateral lungs as well as heterotaxy of abdominal organs (right-sided spleen and inversion of the alimentary and biliary organs). Whole-exome sequencing (WES) identified a heterozygous single-nucleotide change (c.12775T>C) in exon 68 of the DNAH9 gene, which is a rare single-nucleotide polymorphism (SNP) of rs746081639 and results in the amino acid change of p.C4259R. WES also identified a rare SNP of rs763089682 (c.121G>A) in the RSPH1 gene that causes a heterozygous amino acid alteration of p.G41R. The frequencies of both SNPs, C in rs746081639 and A in rs763089682, are 0.00000824, and a polyphen-2 analysis predicted these amino acid changes to be probably damaging, with a score of 1.000. The combination of extremely rare SNPs in DNAH9 and RSPH1 genes might have been the possible mechanism underlying the development of the laterality defect in the present case.

Novel Biallelic DNAH1 Variations Cause Multiple Morphological Abnormalities of the Sperm Flagella

Sperm motility is vital to human reproduction, and malformed sperm flagella can cause male infertility. Individuals with multiple morphological abnormalities of the flagella mostly have absent, short, coiled, bent, and/or irregular-caliber flagella. In this study, a patient with male infertility underwent a physical examination along with his wife. Genetic testing was performed by whole-exome sequencing of the couple, and Sanger sequencing was performed for validation. Novel biallelic variations in the DNAH1: (NM_015512.4) gene consisting of c.1336G>C (p.E446Q) and c.2912G>A (p.R971H) were identified. In silico structural analysis revealed that the amino acid residues affected by the variation were evolutionarily conserved, and the variant p.R971H influenced the stability of the DNAH1 protein. Morphological studies of the patient's sperm showed defects in its flagella. Results of Papanicolaou staining and scanning electron microscopy demonstrated coiled and short flagella with multiple anomalies. Transmission electron microscopy of the sperm flagella showed that the inner dynein arm and radial spoke were absent, and the dense fiber and microtubule doublets were displaced. Quantitative PCR of the mRNA of the patient's sperm showed that the expression of DNALI1 was dramatically reduced. Collectively, these findings elucidated the genetic cause of the family's infertility and provided insight into the functioning of the DNAH1 gene.

Na,K-ATPase Atp1a4 isoform is important for maintaining sperm flagellar shape

PURPOSE

The aim of this study is to investigate the mechanisms by which the testis specific Na,K-ATPase ion transport system (Atp1a4) controls sperm morphology and shape.

METHODS

Sperm from wild-type (WT) and Atp1a4 knockout (Atp1a4 KO) mice were analyzed morphologically, using light, transmission, and scanning electron microscopy; and functionally, applying sperm osmotic challenge and viability tests. In addition, a sperm proteomic study was performed.

RESULTS

Light microscopy confirmed that sperm lacking Atp1a4 present a bend at the junction of the mid- and principal piece of the flagellum. This bend had different degrees of angulation, reaching occasionally a complete flagellar retroflexion. The defect appeared in sperm collected from the cauda epididymis, but not the epididymal caput or the testis. Transmission and scanning electron microscopy revealed a dilation of the cytoplasm at the site of the bend, with fusion of the plasma membrane in overlapping segments of the flagellum. This was accompanied by defects in the axoneme and peri-axonemal structures. Sperm from Atp1a4 KO mice showed an abnormal response to hypoosmotic challenge with decreased viability, suggesting reduced capacity for volume regulation. Exposure to Triton X-100 only partially recovered the flagellar bend of Atp1a4 KO sperm, showing that factors other than osmotic regulation contribute to the flagellar defect. Interestingly, several key sperm structural proteins were expressed in lower amounts in Atp1a4 KO sperm, with no changes in their localization.

CONCLUSIONS

Altogether, our results show that Atp1a4 plays an important role in maintaining the proper shape of the sperm flagellum through both osmotic control and structurally related mechanisms.

Impaired Differentiation of Chronic Obstructive Pulmonary Disease Bronchial Epithelial Cells Grown on Bronchial Scaffolds

Chronic obstructive pulmonary disease (COPD) is characterized by airway inflammation, small airway remodeling, and emphysema. Airway remodeling in patients with COPD involves both the airway epithelium and the subepithelial extracellular matrix (ECM). However, it is currently unknown how epithelial remodeling in COPD airways depends on the relative influence from inherent defects in the epithelial cells and alterations in the ECM. To address this, we analyzed global gene expression in COPD human bronchial epithelial cells (HBEC) and normal HBEC after repopulation on decellularized bronchial scaffolds derived from patients with COPD or donors without COPD. COPD HBEC grown on bronchial scaffolds showed an impaired ability to initiate ciliated-cell differentiation, which was evident on all scaffolds regardless of their origin. In addition, although normal HBEC were less affected by the disease state of the bronchial scaffolds, COPD HBEC showed a gene expression pattern indicating increased proliferation and a retained basal-cell phenotype when grown on COPD bronchial scaffolds compared with normal bronchial scaffolds. By using mass spectrometry, we identified 13 matrisome proteins as being differentially abundant between COPD bronchial scaffolds and normal bronchial scaffolds. These observations are consistent with COPD pathology and suggest that both epithelial cells and the ECM contribute to epithelial-cell remodeling in COPD airways.

Identification of a frame shift mutation in the CCDC151 gene in a Han-Chinese family with Kartagener syndrome

Kartagener syndrome (KS), a subtype of primary ciliary dyskinesia (PCD), is characterized by bronchiectasis, chronic sinusitis, male infertility and situs inversus. KS is a genetically heterogeneous disease that is inherited in an autosomal recessive form; however, X-linked inheritance has also been reported. As of this writing [late 2020], at least 34 loci, most of which have known genes, have been reported in the literature as associating with KS. In the present study, we identified a frame shift mutation, c.167delG (p.G56Dfs*26), in the coiled-coil domain containing 151 gene (CCDC151) responsible for KS in a Han-Chinese family. To our knowledge, this is the first report of a CCDC151 c.167delG mutation in the KS patient. These findings may expand the CCDC151 mutation spectrum of KS, and contribute to future genetic counseling and gene-targeted therapy for this disease.

Limitations and opportunities in the pharmacotherapy of ciliopathies

Ciliopathies are a family of rather diverse conditions, which have been grouped based on the finding of altered or dysfunctional cilia, potentially motile, small cellular antennae extending from the surface of postmitotic cells. Cilia-related disorders include embryonically arising conditions such as Joubert, Usher or Kartagener syndrome, but also afflictions with a postnatal or even adult onset phenotype, i.e. autosomal dominant polycystic kidney disease. The majority of ciliopathies are syndromic rather than affecting only a single organ due to cilia being found on almost any cell in the human body. Overall ciliopathies are considered rare diseases. Despite that, pharmacological research and the strive to help these patients has led to enormous therapeutic advances in the last decade. In this review we discuss new treatment options for certain ciliopathies, give an outlook on promising future therapeutic strategies, but also highlight the limitations in the development of therapeutic approaches of ciliopathies.

Motility of efferent duct cilia aids passage of sperm cells through the male reproductive system

Motile cilia line the efferent ducts of the mammalian male reproductive tract. Several recent mouse studies have demonstrated that a reduced generation of multiple motile cilia in efferent ducts is associated with obstructive oligozoospermia and fertility issues. However, the sole impact of efferent duct cilia dysmotility on male infertility has not been studied so far either in mice or human. Using video microscopy, histological- and ultrastructural analyses, we examined male reproductive tracts of mice deficient for the axonemal motor protein DNAH5: this defect exclusively disrupts the outer dynein arm (ODA) composition of motile cilia but not the ODA composition and motility of sperm flagella. These mice have immotile efferent duct cilia that lack ODAs, which are essential for ciliary beat generation. Furthermore, they show accumulation of sperm in the efferent duct. Notably, the ultrastructure and motility of sperm from these males are unaffected. Likewise, human individuals with loss-of-function DNAH5 mutations present with reduced sperm count in the ejaculate (oligozoospermia) and dilatations of the epididymal head but normal sperm motility, similar to DNAH5 deficient mice. The findings of this translational study demonstrate, in both mice and men, that efferent duct ciliary motility is important for male reproductive fitness and uncovers a novel pathomechanism distinct from primary defects of sperm motility (asthenozoospermia). If future work can identify environmental factors or defects in genes other than DNAH5 that cause efferent duct cilia dysmotility, this will help unravel other causes of oligozoospermia and may influence future practices in genetic and fertility counseling as well as ART.

Axonemal Dynein DNAH5 is Required for Sound Sensation in Drosophila Larvae

Chordotonal neurons are responsible for sound sensation in Drosophila. However, little is known about how they respond to sound with high sensitivity. Using genetic labeling, we found one of the Drosophila axonemal dynein heavy chains, CG9492 (DNAH5), was specifically expressed in larval chordotonal neurons and showed a distribution restricted to proximal cilia. While DNAH5 mutation did not affect the cilium morphology or the trafficking of Inactive, a candidate auditory transduction channel, larvae with DNAH5 mutation had reduced startle responses to sound at low and medium intensities. Calcium imaging confirmed that DNAH5 functioned autonomously in chordotonal neurons for larval sound sensation. Furthermore, disrupting DNAH5 resulted in a decrease of spike firing responses to low-level sound in chordotonal neurons. Intriguingly, DNAH5 mutant larvae displayed an altered frequency tuning curve of the auditory organs. All together, our findings support a critical role of DNAH5 in tuning the frequency selectivity and the sound sensitivity of larval auditory neurons.

Cardiac Development: A Glimpse on Its Translational Contributions

Cardiac development is a complex developmental process that is initiated soon after gastrulation, as two sets of precardiac mesodermal precursors are symmetrically located and subsequently fused at the embryonic midline forming the cardiac straight tube. Thereafter, the cardiac straight tube invariably bends to the right, configuring the first sign of morphological left–right asymmetry and soon thereafter the atrial and ventricular chambers are formed, expanded and progressively septated. As a consequence of all these morphogenetic processes, the fetal heart acquired a four-chambered structure having distinct inlet and outlet connections and a specialized conduction system capable of directing the electrical impulse within the fully formed heart. Over the last decades, our understanding of the morphogenetic, cellular, and molecular pathways involved in cardiac development has exponentially grown. Multiples aspects of the initial discoveries during heart formation has served as guiding tools to understand the etiology of cardiac congenital anomalies and adult cardiac pathology, as well as to enlighten novels approaches to heal the damaged heart. In this review we provide an overview of the complex cellular and molecular pathways driving heart morphogenesis and how those discoveries have provided new roads into the genetic, clinical and therapeutic management of the diseased hearts.

Mucociliary Respiratory Epithelium Integrity in Molecular Defense and Susceptibility to Pulmonary Viral Infections

Mucociliary defense, mediated by the ciliated and goblet cells, is fundamental to respiratory fitness. The concerted action of ciliary movement on the respiratory epithelial surface and the pathogen entrapment function of mucus help to maintain healthy airways. Consequently, genetic or acquired defects in lung defense elicit respiratory diseases and secondary microbial infections that inflict damage on pulmonary function and may even be fatal. Individuals living with chronic and acute respiratory diseases are more susceptible to develop severe coronavirus disease-19 (COVID-19) illness and hence should be proficiently managed. In light of the prevailing pandemic, we review the current understanding of the respiratory system and its molecular components with a major focus on the pathophysiology arising due to collapsed respiratory epithelium integrity such as abnormal ciliary movement, cilia loss and dysfunction, ciliated cell destruction, and changes in mucus rheology. The review includes protein interaction networks of coronavirus infection-manifested implications on the molecular machinery that regulates mucociliary clearance. We also provide an insight into the alteration of the transcriptional networks of genes in the nasopharynx associated with the mucociliary clearance apparatus in humans upon infection by severe acute respiratory syndrome coronavirus-2.

A systems biology framework integrating GWAS and RNA-seq to shed light on the molecular basis of sperm quality in swine

BACKGROUND

Genetic pressure in animal breeding is sparking the interest of breeders for selecting elite boars with higher sperm quality to optimize ejaculate doses and fertility rates. However, the molecular basis of sperm quality is not yet fully understood. Our aim was to identify candidate genes, pathways and DNA variants associated to sperm quality in swine by analysing 25 sperm-related phenotypes and integrating genome-wide association studies (GWAS) and RNA-seq under a systems biology framework.

RESULTS

By GWAS, we identified 12 quantitative trait loci (QTL) associated to the percentage of head and neck abnormalities, abnormal acrosomes and motile spermatozoa. Candidate genes included CHD2, KATNAL2, SLC14A2 and ABCA1. By RNA-seq, we identified a wide repertoire of mRNAs (e.g. PRM1, OAZ3, DNAJB8, TPPP2 and TNP1) and miRNAs (e.g. ssc-miR-30d, ssc-miR-34c, ssc-miR-30c-5p, ssc-miR-191, members of the let-7 family and ssc-miR-425-5p) with functions related to sperm biology. We detected 6128 significant correlations (P-value ≤ 0.05) between sperm traits and mRNA abundances. By expression (e)GWAS, we identified three trans-expression QTL involving the genes IQCJ, ACTR2 and HARS. Using the GWAS and RNA-seq data, we built a gene interaction network. We considered that the genes and interactions that were present in both the GWAS and RNA-seq networks had a higher probability of being actually involved in sperm quality and used them to build a robust gene interaction network. In addition, in the final network we included genes with RNA abundances correlated with more than four semen traits and miRNAs interacting with the genes on the network. The final network was enriched for genes involved in gamete generation and development, meiotic cell cycle, DNA repair or embryo implantation. Finally, we designed a panel of 73 SNPs based on the GWAS, eGWAS and final network data, that explains between 5% (for sperm cell concentration) and 36% (for percentage of neck abnormalities) of the phenotypic variance of the sperm traits.

CONCLUSIONS

By applying a systems biology approach, we identified genes that potentially affect sperm quality and constructed a SNP panel that explains a substantial part of the phenotypic variance for semen quality in our study and that should be tested in other swine populations to evaluate its relevance for the pig breeding sector.

Motile cilia and airway disease

A finely regulated system of airway epithelial development governs the differentiation of motile ciliated cells of the human respiratory tract, conferring the body's mucociliary clearance defence system. Human cilia dysfunction can arise through genetic mutations and this is a cause of debilitating disease morbidities that confer a greatly reduced quality of life. The inherited human motile ciliopathy disorder, primary ciliary dyskinesia (PCD), can arise from mutations in genes affecting various aspects of motile cilia structure and function through deficient production, transport and assembly of cilia motility components or through defective multiciliogenesis. Our understanding about the development of the respiratory epithelium, motile cilia biology and the implications for human pathology has expanded greatly over the past 20 years since isolation of the first PCD gene, rising to now nearly 50 genes. Systems level insights about cilia motility in health and disease have been made possible through intensive molecular and omics (genomics, transcriptomics, proteomics) research, applied in ciliate organisms and in animal and human disease modelling. Here, we review ciliated airway development and the genetic stratification that underlies PCD, for which the underlying genotype can increasingly be connected to biological mechanism and disease prognostics. Progress in this field can facilitate clinical translation of research advances, with potential for great medical impact, e.g. through improvements in ciliopathy disease diagnosis, management, family counselling and by enhancing the potential for future genetically tailored approaches to disease therapeutics.

Genetic underpinnings of asthenozoospermia

Asthenozoospermia (AZS), defined by reduced motility or absent sperm motility, is one of the main causes of male infertility. This condition may be divided into isolated AZS in the absence of other symptoms and syndromic AZS, which is characterized by several concurrent clinical symptoms. Sperm motility depends on fully functional flagellum, energy availability, and the crosstalk of several signaling pathways; therefore, mutations in genes involved in flagellar assembly and motile regulation can cause AZS. Thus, it is crucial to understand the genetic causes and mechanisms contributing to AZS. In this review, we summarize the current knowledge about the particular genes and mechanisms involved in intact flagellum, energy availability, and signaling transduction that could cause human AZS and discuss the respective gene defects known to be responsible for these abnormalities. Additionally, we discuss intracytoplasmic sperm injection outcomes and offspring health where available in these cases.

Primary ciliary dyskinesia relative protein ZMYND10 is involved in regulating ciliary function and intraflagellar transport in Paramecium tetraurelia

Cilia are highly conserved in most eukaryotes and are regarded as an important organelle for motility and sensation in various species. Cilia are microscopic, hair-like cytoskeletal structures that protrude from the cell surface. The major focus in studies of cilia has been concentrated on the ciliary dysfunction in vertebrates that causes multisymptomatic diseases, which together are referred to as ciliopathies. To date, the understanding of ciliopathies has largely depended on the study of ciliary structure and function in different animal models. Zinc finger MYND-type containing 10 (ZMYND10) is a ciliary protein that was recently found to be mutated in patients with primary ciliary dyskinesia (PCD). In Paramecium tetraurelia, we identified two ZMYND10 genes, arising from a whole-genome duplication. Using RNAi, we found that the depletion of ZMYND10 in P. tetraurelia causes severe ciliary defects, thus provoking swimming dysfunction and lethality. Moreover, we found that the absence of ZMYND10 caused the abnormal localization of the intraflagellar transport (IFT) protein IFT43 along cilia. These results suggest that ZMYND10 is involved in the regulation of ciliary function and IFT, which may contribute to the study of PCD pathogenesis.

A novel genetic variant in DNAI2 detected by custom gene panel in a newborn with Primary Ciliary Dyskinesia: case report

BACKGROUND

Primary ciliary dyskinesia (PCD) is a highly heterogeneous genetic disorder caused by defects in motile cilia. The hallmark features of PCD are the chronic infections of the respiratory tract, moreover, clinical manifestations include also laterality defects and risk of male infertility. Clinical phenotypes of PCD are the result of mutations in genes encoding components of axonema or factors involved in axonemal assembly. Recent studies have identified over 45 PCD-associated genes, therefore, molecular analysis represents a powerful diagnostic tool to confirm and uncover new genetic causes of this rare disease.

CASE PRESENTATION

Here, we describe a female infant of Moroccan origin with normal pressure hydrocephalus (NPH) in addition to most common PCD symptoms. Transmission Electron Microscopy (TEM) and molecular tests, such as a Next generation Sequencing panel and a custom array CGH, were performed for diagnosis of PCD. TEM revealed outer dynein arm (ODA) defects, whilst molecular analyses detected a novel 6,9 kb microdeletion in DNAI2 gene.

CONCLUSIONS

Since DNAI2 mutations are very rare, this case report contributes to better delineate the important role of DNAI2 as causative of PCD phenotype, suggesting, furthermore, that the variations in DNAI2 may be as a new genetic risk factor for NPH. Indeed, although the association of hydrocephalus with PCD has been well documented, however, only a small number of human patients show this defect. Furthermore, this study highlights the importance of high-throughput technologies in advancing our understanding of heterogeneous genetic disorders.

Immunofluorescence Analysis as a Diagnostic Tool in a Spanish Cohort of Patients with Suspected Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive rare disease caused by an alteration of ciliary structure. Immunofluorescence, consisting in the detection of the presence and distribution of cilia proteins in human respiratory cells by fluorescence, has been recently proposed as a technique to improve understanding of disease-causing genes and diagnosis rate in PCD. The objective of this study is to determine the accuracy of a panel of four fluorescently labeled antibodies (DNAH5, DNALI1, GAS8 and RSPH4A or RSPH9) as a PCD diagnostic tool in the absence of transmission electron microscopy analysis. The panel was tested in nasal brushing samples of 74 patients with clinical suspicion of PCD. Sixty-eight (91.9%) patients were evaluable for all tested antibodies. Thirty-three cases (44.6%) presented an absence or mislocation of protein in the ciliary axoneme (15 absent and 3 proximal distribution of DNAH5 in the ciliary axoneme, 3 absent DNAH5 and DNALI1, 7 absent DNALI1 and cytoplasmatic localization of GAS8, 1 absent GAS8, 3 absent RSPH9 and 1 absent RSPH4A). Fifteen patients had confirmed or highly likely PCD but normal immunofluorescence results (68.8% sensitivity and 100% specificity). In conclusion, immunofluorescence analysis is a quick, available, low-cost and reliable diagnostic test for PCD, although it cannot be used as a standalone test.

CFAP45 deficiency causes situs abnormalities and asthenospermia by disrupting an axonemal adenine nucleotide homeostasis module

Axonemal dynein ATPases direct ciliary and flagellar beating via adenosine triphosphate (ATP) hydrolysis. The modulatory effect of adenosine monophosphate (AMP) and adenosine diphosphate (ADP) on flagellar beating is not fully understood. Here, we describe a deficiency of cilia and flagella associated protein 45 (CFAP45) in humans and mice that presents a motile ciliopathy featuring situs inversus totalis and asthenospermia. CFAP45-deficient cilia and flagella show normal morphology and axonemal ultrastructure. Proteomic profiling links CFAP45 to an axonemal module including dynein ATPases and adenylate kinase as well as CFAP52, whose mutations cause a similar ciliopathy. CFAP45 binds AMP in vitro, consistent with structural modelling that identifies an AMP-binding interface between CFAP45 and AK8. Microtubule sliding of dyskinetic sperm from Cfap45^−/− mice is rescued with the addition of either AMP or ADP with ATP, compared to ATP alone. We propose that CFAP45 supports mammalian ciliary and flagellar beating via an adenine nucleotide homeostasis module.

The mechanism by which adenosine monophosphate modulates dynein ATPase-mediated ciliary and flagellar beating remains obscure. Here the authors identify an axonemal module including cilia and flagella associated protein 45 that supports adenine nucleotide homeostasis and underlies a human ciliopathy

Motile ciliopathies

Motile cilia are highly complex hair-like organelles of epithelial cells lining the surface of various organ systems. Genetic mutations (usually with autosomal recessive inheritance) that impair ciliary beating cause a variety of motile ciliopathies, a heterogeneous group of rare disorders. The pathogenetic mechanisms, clinical symptoms and severity of the disease depend on the specific affected genes and the tissues in which they are expressed. Defects in the ependymal cilia can result in hydrocephalus, defects in the cilia in the fallopian tubes or in sperm flagella can cause female and male subfertility, respectively, and malfunctional motile monocilia of the left-right organizer during early embryonic development can lead to laterality defects such as situs inversus and heterotaxy. If mucociliary clearance in the respiratory epithelium is severely impaired, the disorder is referred to as primary ciliary dyskinesia, the most common motile ciliopathy. No single test can confirm a diagnosis of motile ciliopathy, which is based on a combination of tests including nasal nitric oxide measurement, transmission electron microscopy, immunofluorescence and genetic analyses, and high-speed video microscopy. With the exception of azithromycin, there is no evidence-based treatment for primary ciliary dyskinesia; therapies aim at relieving symptoms and reducing the effects of reduced ciliary motility.

Bi-allelic DNAH8 Variants Lead to Multiple Morphological Abnormalities of the Sperm Flagella and Primary Male Infertility

Sperm malformation is a direct factor for male infertility. Multiple morphological abnormalities of the flagella (MMAF), a severe form of asthenoteratozoospermia, are characterized by immotile spermatozoa with malformed and/or absent flagella in the ejaculate. Previous studies indicated genetic heterogeneity in MMAF. To further define genetic factors underlying MMAF, we performed whole-exome sequencing in a cohort of 90 Chinese MMAF-affected men. Two cases (2.2%) were identified as carrying bi-allelic missense DNAH8 variants, variants which were either absent or rare in the control human population and were predicted to be deleterious by multiple bioinformatic tools. Re-analysis of exome data from a second cohort of 167 MMAF-affected men from France, Iran, and North Africa permitted the identification of an additional male carrying a DNAH8 homozygous frameshift variant. DNAH8 encodes a dynein axonemal heavy-chain component that is expressed preferentially in the testis. Hematoxylin-eosin staining and electron microscopy analyses of the spermatozoa from men harboring bi-allelic DNAH8 variants showed a highly aberrant morphology and ultrastructure of the sperm flagella. Immunofluorescence assays performed on the spermatozoa from men harboring bi-allelic DNAH8 variants revealed the absent or markedly reduced staining of DNAH8 and its associated protein DNAH17. Dnah8-knockout male mice also presented typical MMAF phenotypes and sterility. Interestingly, intracytoplasmic sperm injections using the spermatozoa from Dnah8-knockout male mice resulted in good pregnancy outcomes. Collectively, our experimental observations from humans and mice demonstrate that DNAH8 is essential for sperm flagellar formation and that bi-allelic deleterious DNAH8 variants lead to male infertility with MMAF.