LRGUK-1 is required for basal body and manchette function during spermatogenesis and male fertility

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

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

A novel bioinformatic approach reveals cooperation between Cancer/Testis genes in basal-like breast tumors

Breast cancer is the most prevalent type of cancer in women worldwide. Within breast tumors, the basal-like subtype has the worst prognosis, prompting the need for new tools to understand, detect, and treat these tumors. Certain germline-restricted genes show aberrant expression in tumors and are known as Cancer/Testis genes; their misexpression has diagnostic and therapeutic applications. Here we designed a new bioinformatic approach to examine Cancer/Testis gene misexpression in breast tumors. We identify several new markers in Luminal and HER-2 positive tumors, some of which predict response to chemotherapy. We then use machine learning to identify the two Cancer/Testis genes most associated with basal-like breast tumors: HORMAD1 and CT83. We show that these genes are expressed by tumor cells and not by the microenvironment, and that they are not expressed by normal breast progenitors; in other words, their activation occurs de novo. We find these genes are epigenetically repressed by DNA methylation, and that their activation upon DNA demethylation is irreversible, providing a memory of past epigenetic disturbances. Simultaneous expression of both genes in breast cells in vitro has a synergistic effect that increases stemness and activates a transcriptional profile also observed in double-positive tumors. Therefore, we reveal a functional cooperation between Cancer/Testis genes in basal breast tumors; these findings have consequences for the understanding, diagnosis, and therapy of the breast tumors with the worst outcomes.

The response of Dual-leucine zipper kinase (DLK) to nocodazole: Evidence for a homeostatic cytoskeletal repair mechanism

Genetic and pharmacological perturbation of the cytoskeleton enhances the regenerative potential of neurons. This response requires Dual-leucine Zipper Kinase (DLK), a neuronal stress sensor that is a central regulator of axon regeneration and degeneration. The damage and repair aspects of this response are reminiscent of other cellular homeostatic systems, suggesting that a cytoskeletal homeostatic response exists. In this study, we propose a framework for understanding DLK mediated neuronal cytoskeletal homeostasis. We demonstrate that low dose nocodazole treatment activates DLK signaling. Activation of DLK signaling results in a DLK-dependent transcriptional signature, which we identify through RNA-seq. This signature includes genes likely to attenuate DLK signaling while simultaneously inducing actin regulating genes. We identify alterations to the cytoskeleton including actin-based morphological changes to the axon. These results are consistent with the model that cytoskeletal disruption in the neuron induces a DLK-dependent homeostatic mechanism, which we term the Cytoskeletal Stress Response (CSR) pathway.

Genomics of post-bottleneck recovery in the northern elephant seal

Populations and species are threatened by human pressure, but their fate is variable. Some depleted populations, such as that of the northern elephant seal (Mirounga angustirostris), recover rapidly even when the surviving population was small. The northern elephant seal was hunted extensively and taken by collectors between the early 1800s and 1892, suffering an extreme population bottleneck as a consequence. Recovery was rapid and now there are over 200,000 individuals. We sequenced 260 modern and 8 historical northern elephant seal nuclear genomes to assess the impact of the population bottleneck on individual northern elephant seals and to better understand their recovery. Here we show that inbreeding, an increase in the frequency of alleles compromised by lost function, and allele frequency distortion, reduced the fitness of breeding males and females, as well as the performance of adult females on foraging migrations. We provide a detailed investigation of the impact of a severe bottleneck on fitness at the genomic level and report on the role of specific gene systems.

Targeted mutation and inactivation of the kinesin light chain 3 protein-encoding gene have no impact on mouse fertility†

The kinesin light chain 3 protein (KLC3) is the only member of the kinesin light chain protein family that was identified in post-meiotic mouse male germ cells. It plays a role in the formation of the sperm midpiece through its association with both spermatid mitochondria and outer dense fibers (ODF). Previous studies showed a significant correlation between its expression level and sperm motility and quantitative semen parameters in humans, while the overexpression of a KLC3-mutant protein unable to bind ODF also affected the same traits in mice. To further assess the role of KLC3 in fertility, we used CRISPR/Cas9 genome editing in mice and investigated the phenotypes induced by the invalidation of the gene or of a functional domain of the protein. Both approaches gave similar results, i.e. no detectable change in male or female fertility. Testis histology, litter size and sperm count were not altered. Apart from the line-dependent alterations of Klc3 mRNA levels, testicular transcriptome analysis did not reveal any other changes in the genes tested. Western analysis supported the absence of KLC3 in the gonads of males homozygous for the inactivating mutation and a strong decrease in expression in males homozygous for the allele lacking one out of the five tetratricopeptide repeats. Overall, these observations raise questions about the supposedly critical role of this kinesin in reproduction, at least in mice where its gene mutation or inactivation did not translate into fertility impairment.

The response of Dual-Leucine Zipper Kinase (DLK) to nocodazole: evidence for a homeostatic cytoskeletal repair mechanism

Genetic and pharmacological perturbation of the cytoskeleton enhances the regenerative potential of neurons. This response requires Dual-leucine Zipper Kinase (DLK), a neuronal stress sensor that is a central regulator of axon regeneration and degeneration. The damage and repair aspects of this response are reminiscent of other cellular homeostatic systems, suggesting that a cytoskeletal homeostatic response exists. In this study, we propose a framework for understanding DLK mediated neuronal cytoskeletal homeostasis. We demonstrate that a) low dose nocodazole treatment activates DLK signaling and b) DLK signaling mitigates the microtubule damage caused by the cytoskeletal perturbation. We also perform RNA-seq to discover a DLK-dependent transcriptional signature. This signature includes genes likely to attenuate DLK signaling while simultaneously inducing actin regulating genes and promoting actin-based morphological changes to the axon. These results are consistent with the model that cytoskeletal disruption in the neuron induces a DLK-dependent homeostatic mechanism, which we term the Cytoskeletal Stress Response (CSR) pathway.

ADAD1 is required for normal translation of nuclear pore and transport protein transcripts in spermatids of Mus musculus†

ADAD1 is a testis-specific RNA-binding protein expressed in post-meiotic spermatids whose loss leads to defective sperm and male infertility. However, the drivers of the Adad1 phenotype remain unclear. Morphological and functional analysis of Adad1 mutant sperm showed defective DNA compaction, abnormal head shaping, and reduced motility. Mutant testes demonstrated minimal transcriptome changes; however, ribosome association of many transcripts was reduced, suggesting ADAD1 may be required for their translational activation. Further, immunofluorescence of proteins encoded by select transcripts showed delayed protein accumulation. Additional analyses demonstrated impaired subcellular localization of multiple proteins, suggesting protein transport is also abnormal in Adad1 mutants. To clarify the mechanism giving rise to this, the manchette, a protein transport microtubule network, and the LINC (linker of nucleoskeleton and cytoskeleton) complex, which connects the manchette to the nuclear lamin, were assessed across spermatid development. Proteins of both displayed delayed translation and/or localization in mutant spermatids implicating ADAD1 in their regulation, even in the absence of altered ribosome association. Finally, ADAD1's impact on the NPC (nuclear pore complex), a regulator of both the manchette and the LINC complex, was examined. Reduced ribosome association of NPC encoding transcripts and reduced NPC protein abundance along with abnormal localization in Adad1 mutants confirmed ADAD1's impact on translation is required for a NPC in post-meiotic germ cells. Together, these studies lead to a model whereby ADAD1's influence on nuclear transport leads to deregulation of the LINC complex and the manchette, ultimately generating the range of physiological defects observed in the Adad1 phenotype.

A preliminary study of calcium channel-associated mRNA and miRNA networks in post-traumatic epileptic rats

The calcium channels are the main pathogenesis and therapeutic target for post-traumatic epilepsy (PTE). However, differentially expressed miRNAs (DEMs) and mRNAs associated with calcium channels in PTE and their interactions are poorly understood. We produced a PTE model in rats and conducted RNA-seq in PTE rats. Gene annotation was used to verify differentially expressed mRNAs related to calcium channels. RNAhybrid, PITA, and Miranda prediction were used to build the miRNA-mRNA pairs. Furthermore, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were used for the functional enrichment analysis of DEMs. The quantification changes of mRNA and miRNA were verified by RT-qPCR. There were 431 identified differentially expressed genes (DEGs) in PTE rats compared with the sham group, of which five mRNAs and 7 miRNAs were related to calcium channels. The miRNA-mRNA network suggested a negative correlation between 11 pairs of miRNA-mRNA involved in the p53 signaling pathway, HIF-1 signaling pathway. RT-qPCR verified three upregulated mRNAs in PTE rats, associated with 7 DEMs negatively related to them, respectively. This study has revealed the changes in miRNA-mRNA pairs associated with calcium channels in PTE, which might contribute to the further interpretation of potential underlying molecular mechanisms of PTE and the discovery of promising diagnostics.

Actin-related protein ACTL7B ablation leads to OAT with multiple morphological abnormalities of the flagellum and male infertility in mice†

The formation of fertilisation-competent sperm requires spermatid morphogenesis (spermiogenesis), a poorly understood program that involves complex coordinated restructuring and specialised cytoskeletal structures. A major class of cytoskeletal regulators are the actin-related proteins (ARPs), which include conventional actin variants, and related proteins that play essential roles in complexes regulating actin dynamics, intracellular transport, and chromatin remodeling. Multiple testis-specific ARPs are well conserved among mammals, but their functional roles are unknown. One of these is actin-like 7b (Actl7b) that encodes an orphan ARP highly similar to the ubiquitously expressed beta actin (ACTB). Here we report ACTL7B is expressed in human and mouse spermatids through the elongation phase of spermatid development. In mice, ACTL7B specifically localises to the developing acrosome, within the nucleus of early spermatids, and to the flagellum connecting region. Based on this localisation pattern and high level of sequence conservation in mice, humans, and other mammals, we examined the requirement for ACTL7B in spermiogenesis by generating and characterising the reproductive phenotype of male Actl7b KO mice. KO mice were infertile, with severe and variable oligoteratozoospermia (OAT) and multiple morphological abnormalities of the flagellum (MMAF) and sperm head. These defects phenocopy human OAT and MMAF, which are leading causes of idiopathic male infertility. In conclusion, this work identifies ACTL7B as a key regulator of spermiogenesis that is required for male fertility.

Circular RNAs: Novel Biomarkers in Spermatogenesis Defects and Male Infertility

Circular RNAs (circRNAs) are a new class of endogenous non-coding RNAs involved in several cellular and biological processes, including gene expression regulation, microRNA function, transcription regulation, and translation modification. Therefore, these non-coding RNAs have important roles in the pathogenesis of various diseases. Male infertility is mainly due to abnormal sperm parameters such as motility, morphology, and concentration. Recent studies have confirmed the role of circRNAs in spermatogenesis, and the expression of several circRNAs is confirmed in seminal plasma, spermatozoa, and testicular tissue. It is suggested that deregulation of circRNAs is involved in different types of male infertility, including azoospermia, oligozoospermia, and asthenozoospermia. In the present review, we aimed to discuss the potential roles of circRNAs in spermatogenesis failure, sperm defects, and male infertility. Due to their conserved and special structure and tissue-specific expression pattern, circRNAs can be applied as reliable noninvasive molecular biomarkers, therapeutic and pharmaceutical targets in male infertility.

Genome-wide methylation analyses of human sperm unravel novel differentially methylated regions in asthenozoospermia

Aims & objectives: To investigate DNA methylation patterns in asthenozoospermic and normozoospermic sperm and to explore the potential roles of differential methylations in the etiology of the disease. Materials & methods: The authors performed whole-genome bisulfite sequencing analysis between normozoospermic controls and asthenozoospermic individuals. Results: The authors identified 238 significant differentially methylated regions. These differentially methylated regions were annotated to 114 protein-coding genes, with many genes showing associations with spermatogenesis, sperm motility etc. Conclusion: There are plenty of genomic regions exhibiting altered DNA methylation in asthenozoospermia, a number of which are located within or adjacent to sperm-related genes, suggesting novel methylation markers of asthenozoospermia and potential epigenetic regulation mechanisms through DNA methylation in the disease.

PFN4 is required for manchette development and acrosome biogenesis during mouse spermiogenesis

Profilin 4 (Pfn4) is expressed during spermiogenesis and localizes to the acrosome-acroplaxome-manchette complex. Here, we generated PFN4-deficient mice, with sperm displaying severe impairment in manchette formation. Interestingly, HOOK1 staining suggests that the perinuclear ring is established; however, ARL3 staining is disrupted, suggesting that lack of PFN4 does not interfere with the formation of the perinuclear ring and initial localization of HOOK1, but impedes microtubular organization of the manchette. Furthermore, amorphous head shape and flagellar defects were detected, resulting in reduced sperm motility. Disrupted cis- and trans-Golgi networks and aberrant production of proacrosomal vesicles caused impaired acrosome biogenesis. Proteomic analysis showed that the proteins ARF3, SPECC1L and FKBP1, which are involved in Golgi membrane trafficking and PI3K/AKT pathway, are more abundant in Pfn4^−/− testes. Levels of PI3K, AKT and mTOR were elevated, whereas AMPK level was reduced, consistent with inhibition of autophagy. This seems to result in blockage of autophagic flux, which could explain the failure in acrosome formation. In vitro fertilization demonstrated that PFN4-deficient sperm is capable of fertilizing zona-free oocytes, suggesting a potential treatment for PFN4-related human infertility.

Summary: PFN4-deficient male mice exhibit impaired acrosome formation and malformation of the manchette, leading to amorphous sperm head shape, flagellar abnormalities and sterility.

The Sperm Olfactory Receptor OLFR601 is Dispensable for Mouse Fertilization

Fertilization involves the fusion of two gametes by means of yet unknown membrane binding and fusion events. Over the last years, many sperm proteins have been uncovered to play essential roles in sperm-egg fusion in mammals, but their precise role in fertilization remains unknown, being unclear how these proteins interact with each other or with other yet unknown sperm proteins. The aim of this study has been to identify possible sperm proteins interacting with TMEM95, a protein essential for fertilization located in the sperm membrane. A list of 41 sperm proteins that were pulled down with TMEM95 and identified by mass spectrometry did not include other sperm proteins known to play a role in fertilization, suggesting an independent role of TMEM95 in fertilization. Between these lists, OLFR601 is allocated to the acrosomal region and may mediate affinity for an odorant involved in fertilization. However, Olfr601 disruption did not impair the sperm fertilization ability, suggesting that its function may be redundant with that of other sperm proteins.

Sperm bauplan and function and underlying processes of sperm formation and selection

The spermatozoon is a highly differentiated and polarized cell, with two main structures: the head, containing a haploid nucleus and the acrosomal exocytotic granule, and the flagellum, which generates energy and propels the cell; both structures are connected by the neck. The sperm's main aim is to participate in fertilization, thus activating development. Despite this common bauplan and function, there is an enormous diversity in structure and performance of sperm cells. For example, mammalian spermatozoa may exhibit several head patterns and overall sperm lengths ranging from ∼30 to 350 µm. Mechanisms of transport in the female tract, preparation for fertilization, and recognition of and interaction with the oocyte also show considerable variation. There has been much interest in understanding the origin of this diversity, both in evolutionary terms and in relation to mechanisms underlying sperm differentiation in the testis. Here, relationships between sperm bauplan and function are examined at two levels: first, by analyzing the selective forces that drive changes in sperm structure and physiology to understand the adaptive values of this variation and impact on male reproductive success and second, by examining cellular and molecular mechanisms of sperm formation in the testis that may explain how differentiation can give rise to such a wide array of sperm forms and functions.

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

Background

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

Methods

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

Main findings (Results)

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

Conclusion

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

Long Noncoding RNAs: Recent Insights into Their Role in Male Infertility and Their Potential as Biomarkers and Therapeutic Targets

Long noncoding RNAs (lncRNAs) are composed of nucleotides located in the nucleus and cytoplasm; these are transcribed by RNA polymerase II and are greater than 200 nt in length. LncRNAs fulfill important functions in a variety of biological processes, including genome imprinting, cell differentiation, apoptosis, stem cell pluripotency, X chromosome inactivation and nuclear transport. As high throughput sequencing technology develops, a substantial number of lncRNAs have been found to be related to a variety of biological processes, such as development of the testes, maintaining the self-renewal and differentiation of spermatogonial stem cells, and regulating spermatocyte meiosis. These indicate that lncRNAs can be used as biomarkers and potential therapeutic targets for male infertility. However, only a few comprehensive reviews have described the role of lncRNAs in male reproduction. In this paper, we summarize recent findings relating to the role of lncRNAs in spermatogenesis, their potential as biomarkers for male infertility and the relationship between reproductive arrest and transgenerational effects. Finally, we suggest specific targets for the treatment of male infertility from the perspective of lncRNAs.

Adenylyl cyclase 3 deficiency results in dysfunction of blood-testis barrier during mouse spermiogenesis

Human infertility has become a global medical and social health problem. Mice deficient in type 3 adenylyl cyclase (AC3), a key enzyme that synthesizes cyclic adenosine monophosphate (cAMP), develop male infertility, although the underlying molecular mechanisms remain unknown. We performed a label-free quantitative (LFQ) proteomics analyses to identify testicular differentially expressed proteins (DEPs) and their respective biological processes. Furthermore, histological examination demonstrated that AC3 deficiency in mice led to mild impairment of spermatogenesis, including the thinning of seminiferous epithelium and local lesions in the testis. We further identified that the integrity of the blood-testis barrier (BTB) was impaired in AC3 knockout (AC3^-/-) mice accompanied with the reduction in the expression of tight junctions (TJs) and ectoplasmic specialization (ESs)-related proteins. In addition, the deletion of AC3 in mice also reduced the germ cell proliferation, increased apoptosis, and decreased lipid deposition in the seminiferous tubules. Collectively, our results revealed a role of AC3 in regulating the BTB integrity during spermatogenesis. Thus, our findings provide new perspectives for future research in male infertility.

AXDND1, a novel testis-enriched gene, is required for spermiogenesis and male fertility

Spermiogenesis is a complex process depending on the sophisticated coordination of a myriad of testis-enriched gene regulations. The regulatory pathways that coordinate this process are not well understood, and we demonstrate here that AXDND1, as a novel testis-enriched gene is essential for spermiogenesis and male fertility. AXDND1 is exclusively expressed in the round and elongating spermatids in humans and mice. We identified two potentially deleterious mutations of AXDND1 unique to non‐obstructive azoospermia (NOA) patients through selected exonic sequencing. Importantly, Axdnd1 knockout males are sterile with reduced testis size caused by increased germ cell apoptosis and sloughing, exhibiting phenotypes consistent with oligoasthenoteratozoospermia. Axdnd1 mutated late spermatids showed head deformation, outer doublet microtubules deficiency in the axoneme, and loss of corresponding accessory structures, including outer dense fiber (ODF) and mitochondria sheath. These phenotypes were probably due to the perturbed behavior of the manchette, a dynamic structure where AXDND1 was localized. Our findings establish AXDND1 as a novel testis-enrich gene essential for spermiogenesis and male fertility probably by regulating the manchette dynamics, spermatid head shaping, sperm flagellum assembly.

Structural organization of the C1b projection within the ciliary central apparatus

Motile cilia have a '9+2' structure containing nine doublet microtubules and a central apparatus (CA) composed of two singlet microtubules with associated projections. The CA plays crucial roles in regulating ciliary motility. Defects in CA assembly or function usually result in motility-impaired or paralyzed cilia, which in humans causes disease. Despite their importance, the protein composition and functions of most CA projections remain largely unknown. Here, we combined genetic, proteomic and cryo-electron tomographic approaches to compare the CA of wild-type Chlamydomonas reinhardtii with those of three CA mutants. Our results show that two proteins, FAP42 and FAP246, are localized to the L-shaped C1b projection of the CA, where they interact with the candidate CA protein FAP413. FAP42 is a large protein that forms the peripheral 'beam' of the C1b projection, and the FAP246-FAP413 subcomplex serves as the 'bracket' between the beam (FAP42) and the C1b 'pillar' that attaches the projection to the C1 microtubule. The FAP246-FAP413-FAP42 complex is essential for stable assembly of the C1b, C1f and C2b projections, and loss of these proteins leads to ciliary motility defects.

Detecting the selection signatures in Chinese Duroc,Landrace, Yorkshire, Liangshan, and Qingyu pigs

Here we used two kinds of chips data from 5 pig breeds, Chinese Duroc (DD), Landrace (LL), Yorkshire (YY), Liangshan (LS), and Qingyu pigs (QY) in China to identify genes which show evidence of selection during domestication. Four breed pairs, LS-YY, QY-YY, DD-YY, and LL-YY pair, were performed to detect selection signatures using the Fst method. Then we identified a list of genes that played key roles in domestication and artificial selection. For example, the PTPRM gene was shared in LS-YY, QY-YY, and DD-YY pairs and it regulates a variety of cellular processes including cell growth, differentiation as signaling molecules. The HACD3 gene was shared in QY-YY and DD-YY pairs, and the HACD3 protein is involved in the production of very long-chain fatty acids of different chain lengths. Besides, the MYH11 gene that related to muscle contraction was found in LS-YY and LL-YY pair. These results suggested that genes related to immunity, disease resistance, and metabolism were subjected to strong selection pressure in Chinese domestic pigs in the progress of domestication and evolution; however, genes related to appearance, production performance, and reproduction were undergone strong artificial selection in commercial pig breeds.

Human-modified canids in human-modified landscapes: The evolutionary consequences of hybridization for grey wolves and free-ranging domestic dogs

Introgressive hybridization between domestic animals and their wild relatives is an indirect form of human-induced evolution, altering gene pools and phenotypic traits of wild and domestic populations. Although this process is well documented in many taxa, its evolutionary consequences are poorly understood. In this study, we assess introgression patterns in admixed populations of Eurasian wolves and free-ranging domestic dogs (FRDs), identifying chromosomal regions with significantly overrepresented hybrid ancestry and assessing whether genes located within these regions show signatures of selection. Although the dog admixture proportion in West Eurasian wolves (2.7%) was greater than the wolf admixture proportion in FRDs (0.75%), the number and average length of chromosomal blocks showing significant overrepresentation of hybrid ancestry were smaller in wolves than FRDs. In wolves, 6% of genes located within these blocks showed signatures of positive selection compared to 23% in FRDs. We found that introgression from wolves may provide a considerable adaptive advantage to FRDs, counterbalancing some of the negative effects of domestication, which can include reduced genetic diversity and excessive tameness. In wolves, introgression from FRDs is mostly driven by drift, with a small number of positively selected genes associated with brain function and behaviour. The predominance of drift may be the consequence of small effective size of wolf populations, which reduces efficiency of selection for weakly advantageous or against weakly disadvantageous introgressed variants. Small wolf population sizes result largely from human-induced habitat loss and hunting, thus linking introgression rates to anthropogenic processes. Our results imply that maintenance of large population sizes should be an important element of wolf management strategies aimed at reducing introgression rates of dog-derived variants.

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

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

The molecular mechanisms underlying acrosome biogenesis elucidated by gene-manipulated mice

Sexual reproduction requires the fusion of two gametes in a multistep and multifactorial process termed fertilization. One of the main steps that ensures successful fertilization is acrosome reaction. The acrosome, a special kind of organelle with a cap-like structure that covers the anterior portion of sperm head, plays a key role in the process. Acrosome biogenesis begins with the initial stage of spermatid development, and it is typically divided into four successive phases: the Golgi phase, cap phase, acrosome phase, and maturation phase. The run smoothly of above processes needs an active and specific coordination between the all kinds of organelles (endoplasmic reticulum, trans-golgi network and nucleus) and cytoplasmic structures (acroplaxome and manchette). During the past two decades, an increasingly genes have been discovered to be involved in modulating acrosome formation. Most of these proteins interact with each other and show a complicated molecular regulatory mechanism to facilitate the occurrence of this event. This Review focuses on the progresses of studying acrosome biogenesis using gene-manipulated mice and highlights an emerging molecular basis of mammalian acrosome formation.

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

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

Central Apparatus, the Molecular Kickstarter of Ciliary and Flagellar Nanomachines

Motile cilia and homologous organelles, the flagella, are an early evolutionarily invention, enabling primitive eukaryotic cells to survive and reproduce. In animals, cilia have undergone functional and structural speciation giving raise to typical motile cilia, motile nodal cilia, and sensory immotile cilia. In contrast to other cilia types, typical motile cilia are able to beat in complex, two-phase movements. Moreover, they contain many additional structures, including central apparatus, composed of two single microtubules connected by a bridge-like structure and assembling numerous complexes called projections. A growing body of evidence supports the important role of the central apparatus in the generation and regulation of the motile cilia movement. Here we review data concerning the central apparatus structure, protein composition, and the significance of its components in ciliary beating regulation.

Integrated mRNA and miRNA expression profile analysis of female and male gonads in Hyriopsis cumingii

Hyriopsis cumingii is an important species for freshwater pearl cultivation in China. In terms of pearl production, males have larger pearls and better glossiness than females, but there are few reports focusing on the sex of H. cumingii. In this study, six mRNA and six microRNA (miRNA) libraries were prepared from ovaries and testes. Additionally, 28,502 differentially expressed genes (DEGs) and 32 differentially expressed miRNAs (DEMs) were identified. Compared with testis, 14,360 mRNAs and 20 miRNAs were up-regulated in ovary, 14,142 mRNAs and 12 miRNAs were down-regulated. In DEGs, the known genes related to sex determinism and/or differentiation were also identified, such as DMRT1, SOX9, SF1 for males, FOXL2 for females, and other potentially significant candidate genes. Three sex-related pathways have also been identified, which are Wnt, Notch, and TGF-beta. In 32 DEMs, the three miRNAs (miR-9-5p, miR-92, miR-184) were paid more attention, they predicted 28 target genes, which may also be candidates for sex-related miRNAs and genes. Differential miRNAs target genes analysis reveals the pathway associated with oocyte meiosis and spermatogenesis. Overall, the findings of the study provide significant insights to enhance our understanding of sex differentiation and/or sex determination mechanisms for H. cumingii.

Haploid male germ cells-the Grand Central Station of protein transport

BACKGROUND

The precise movement of proteins and vesicles is an essential ability for all eukaryotic cells. Nowhere is this more evident than during the remarkable transformation that occurs in spermiogenesis-the transformation of haploid round spermatids into sperm. These transformations are critically dependent upon both the microtubule and the actin cytoskeleton, and defects in these processes are thought to underpin a significant percentage of human male infertility.

OBJECTIVE AND RATIONALE

This review is aimed at summarising and synthesising the current state of knowledge around protein/vesicle transport during haploid male germ cell development and identifying knowledge gaps and challenges for future research. To achieve this, we summarise the key discoveries related to protein transport using the mouse as a model system. Where relevant, we anchored these insights to knowledge in the field of human spermiogenesis and the causality of human male infertility.

SEARCH METHODS

Relevant studies published in English were identified using PubMed using a range of search terms related to the core focus of the review-protein/vesicle transport, intra-flagellar transport, intra-manchette transport, Golgi, acrosome, manchette, axoneme, outer dense fibres and fibrous sheath. Searches were not restricted to a particular time frame or species although the emphasis within the review is on mammalian spermiogenesis.

OUTCOMES

Spermiogenesis is the final phase of sperm development. It results in the transformation of a round cell into a highly polarised sperm with the capacity for fertility. It is critically dependent on the cytoskeleton and its ability to transport protein complexes and vesicles over long distances and often between distinct cytoplasmic compartments. The development of the acrosome covering the sperm head, the sperm tail within the ciliary lobe, the manchette and its role in sperm head shaping and protein transport into the tail, and the assembly of mitochondria into the mid-piece of sperm, may all be viewed as a series of overlapping and interconnected train tracks. Defects in this redistribution network lead to male infertility characterised by abnormal sperm morphology (teratozoospermia) and/or abnormal sperm motility (asthenozoospermia) and are likely to be causal of, or contribute to, a significant percentage of human male infertility.

WIDER IMPLICATIONS

A greater understanding of the mechanisms of protein transport in spermiogenesis offers the potential to precisely diagnose cases of male infertility and to forecast implications for children conceived using gametes containing these mutations. The manipulation of these processes will offer opportunities for male-based contraceptive development. Further, as increasingly evidenced in the literature, we believe that the continuous and spatiotemporally restrained nature of spermiogenesis provides an outstanding model system to identify, and de-code, cytoskeletal elements and transport mechanisms of relevance to multiple tissues.

Dlec1 is required for spermatogenesis and male fertility in mice

Deleted in lung and esophageal cancer 1 (DLEC1) is a tumour suppressor gene that is downregulated in various cancers in humans; however, the physiological and molecular functions of DLEC1 are still unclear. This study investigated the critical role of Dlec1 in spermatogenesis and male fertility in mice. Dlec1 was significantly expressed in testes, with dominant expression in germ cells. We disrupted Dlec1 in mice and analysed its function in spermatogenesis and male fertility. Dlec1 deletion caused male infertility due to impaired spermatogenesis. Spermatogenesis progressed normally to step 8 spermatids in Dlec1^−/− mice, but in elongating spermatids, we observed head deformation, a shortened tail, and abnormal manchette organization. These phenotypes were similar to those of various intraflagellar transport (IFT)-associated gene-deficient sperm. In addition, DLEC1 interacted with tailless complex polypeptide 1 ring complex (TRiC) and Bardet–Biedl Syndrome (BBS) protein complex subunits, as well as α- and β-tubulin. DLEC1 expression also enhanced primary cilia formation and cilia length in A549 lung adenocarcinoma cells. These findings suggest that DLEC1 is a possible regulator of IFT and plays an essential role in sperm head and tail formation in mice.

A genome-wide association study revealed five SNPs affecting 8-month weight in sheep

Lamb weight at 8 months of age is an important trait in the sheep industry in terms of the onset of puberty around this age; however, knowledge of its effective genetic factors is limited. Therefore, a GWAS using the 50K SNP-Chip was performed on 96 Baluchi sheep to identify the genomic regions associated with 8-month weight. The results of the present study revealed five SNPs on chromosomes 4, 14 and 16 at 5% chromosome-wide significance level, jointly accounting for 0.95% of total genetic variance. Four genes - MTPN, HYDIN, LRGUK and ZFP90 - were found in 50 kb intervals around the significant SNPs, of which MTPN is involved in regulation of skeletal muscle growth. Our results may provide a new vision to identify the genomic regions affecting growth traits in sheep.

Sperm Differentiation: The Role of Trafficking of Proteins

Sperm differentiation encompasses a complex sequence of morphological changes that takes place in the seminiferous epithelium. In this process, haploid round spermatids undergo substantial structural and functional alterations, resulting in highly polarized sperm. Hallmark changes during the differentiation process include the formation of new organelles, chromatin condensation and nuclear shaping, elimination of residual cytoplasm, and assembly of the sperm flagella. To achieve these transformations, spermatids have unique mechanisms for protein trafficking that operate in a coordinated fashion. Microtubules and filaments of actin are the main tracks used to facilitate the transport mechanisms, assisted by motor and non-motor proteins, for delivery of vesicular and non-vesicular cargos to specific sites. This review integrates recent findings regarding the role of protein trafficking in sperm differentiation. Although a complete characterization of the interactome of proteins involved in these temporal and spatial processes is not yet known, we propose a model based on the current literature as a framework for future investigations.

Identification of circular RNAs in porcine sperm and evaluation of their relation to sperm motility

Circular RNAs (circRNAs) are emerging as a novel class of noncoding RNAs which potential role as gene regulators is quickly gaining interest. circRNAs have been studied in different tissues and cell types across several animal species. However, a thorough characterization of the circRNAome in ejaculated sperm remains unexplored. In this study, we profiled the sperm circRNA catalogue using 40 porcine ejaculates. A complex population of 1,598 circRNAs was shared in at least 30 of the 40 samples. Generally speaking, the predicted circRNAs presented low abundances and were tissue-specific. Around 80% of the circRNAs identified in the boar sperm were reported as novel. Results from abundance correlation between circRNAs and miRNAs together with the prediction of microRNA (miRNA) target sites in circRNAs suggested that circRNAs may act as miRNA sponges. Moreover, we found significant correlations between the abundance of 148 exonic circRNAs and sperm motility parameters. Two of these correlations, involving ssc_circ_1458 and ssc_circ_1321, were confirmed by RT-qPCR using 36 additional samples with extreme and opposite sperm motility values. Our study provides a thorough characterization of circRNAs in sperm and suggests that circRNAs hold potential as noninvasive biomarkers for sperm quality and male fertility.

Long noncoding RNAs expression profile and long noncoding RNA-mediated competing endogenous RNA network in nonobstructive azoospermia patients

Aim: To analyze the expression profile and competing endogenous RNA (ceRNA) network of long noncoding RNAs (lncRNAs) in nonobstructive azoospermia (NOA). Materials & methods: The lncRNA expression profile in NOA was determined by microarray reanalysis. Differential expression analysis was performed by R software. The ceRNA network was constructed using correlation analysis and gene target miRNA prediction. Metascape was used for enrichment analysis. Again ceRNA network was validated by quantitative real-time PCR. Results: Many lncRNAs are differently expressed in NOA. LncRNAs might participate in spermatogenesis through ceRNA mechanism. The ceRNA network included male gamete generation and other pathways. LINC00467 in the network regulated the expression of LRGUK and TDRD6. Conclusion: LncRNAs are involved in NOA and potential biomarkers and therapeutic targets for NOA.

HIPK4 is essential for murine spermiogenesis

Mammalian spermiogenesis is a remarkable cellular transformation, during which round spermatids elongate into chromatin-condensed spermatozoa. The signaling pathways that coordinate this process are not well understood, and we demonstrate here that homeodomain-interacting protein kinase 4 (HIPK4) is essential for spermiogenesis and male fertility in mice. HIPK4 is predominantly expressed in round and early elongating spermatids, and Hipk4 knockout males are sterile, exhibiting phenotypes consistent with oligoasthenoteratozoospermia. Hipk4 mutant sperm have reduced oocyte binding and are incompetent for in vitro fertilization, but they can still produce viable offspring via intracytoplasmic sperm injection. Optical and electron microscopy of HIPK4-null male germ cells reveals defects in the filamentous actin (F-actin)-scaffolded acroplaxome during spermatid elongation and abnormal head morphologies in mature spermatozoa. We further observe that HIPK4 overexpression induces branched F-actin structures in cultured fibroblasts and that HIPK4 deficiency alters the subcellular distribution of an F-actin capping protein in the testis, supporting a role for this kinase in cytoskeleton remodeling. Our findings establish HIPK4 as an essential regulator of sperm head shaping and potential target for male contraception.

The testis-specific LINC component SUN3 is essential for sperm head shaping during mouse spermiogenesis

Sperm head shaping is a key event in spermiogenesis and is tightly controlled via the acrosome-manchette network. Linker of nucleoskeleton and cytoskeleton (LINC) complexes consist of Sad1 and UNC84 domain-containing (SUN) and Klarsicht/ANC-1/Syne-1 homology (KASH) domain proteins and form conserved nuclear envelope bridges implicated in transducing mechanical forces from the manchette to sculpt sperm nuclei into a hook-like shape. However, the role of LINC complexes in sperm head shaping is still poorly understood. Here we assessed the role of SUN3, a testis-specific LINC component harboring a conserved SUN domain, in spermiogenesis. We show that CRISPR/Cas9-generated Sun3 knockout male mice are infertile, displaying drastically reduced sperm counts and a globozoospermia-like phenotype, including a missing, mislocalized, or fragmented acrosome, as well as multiple defects in sperm flagella. Further examination revealed that the sperm head abnormalities are apparent at step 9 and that the sperm nuclei fail to elongate because of the absence of manchette microtubules and perinuclear rings. These observations indicate that Sun3 deletion likely impairs the ability of the LINC complex to transduce the cytoskeletal force to the nuclear envelope, required for sperm head elongation. We also found that SUN3 interacts with SUN4 in mouse testes and that the level of SUN4 proteins is drastically reduced in Sun3-null mice. Altogether, our results indicate that SUN3 is essential for sperm head shaping and male fertility, providing molecular clues regarding the underlying pathology of the globozoospermia-like phenotype.

Toward Development of the Male Pill: A Decade of Potential Non-hormonal Contraceptive Targets

With the continued steep rise of the global human population, and the paucity of safe and practical contraceptive options available to men, the need for development of effective and reversible non-hormonal methods of male fertility control is widely recognized. Currently there are several contraceptive options available to men, however, none of the non-hormonal alternatives have been clinically approved. To advance progress in the development of a safe and reversible contraceptive for men, further identification of novel reproductive tract-specific druggable protein targets is required. Here we provide an overview of genes/proteins identified in the last decade as specific or highly expressed in the male reproductive tract, with deletion phenotypes leading to complete male infertility in mice. These phenotypes include arrest of spermatogenesis and/or spermiogenesis, abnormal spermiation, abnormal spermatid morphology, abnormal sperm motility, azoospermia, globozoospermia, asthenozoospermia, and/or teratozoospermia, which are all desirable outcomes for a novel male contraceptive. We also consider other associated deletion phenotypes that could impact the desirability of a potential contraceptive. We further discuss novel contraceptive targets underscoring promising leads with the objective of presenting data for potential druggability and whether collateral effects may exist from paralogs with close sequence similarity.

Testis transcriptome profiling identified genes involved in spermatogenic arrest of cattleyak

Background

Cattleyak are the hybrid offspring between cattle and yak and combine yak hardiness with cattle productivity. Much attempt has been made to examine the mechanisms of male sterility caused by spermatogenic arrest, but yet there is no research systematically and precisely elucidated testis gene expression profiling between cattleyak and yak.

Methods

To explore the higher resolution comparative transcriptome map between the testes of yak and cattleyak, and further analyze the mRNA expression dynamics of spermatogenic arrest in cattleyak. We characterized the comparative transcriptome profile from the testes of yak and cattleyak using high-throughput sequencing. Then we used quantitative analysis to validate several differentially expressed genes (DEGs) in testicular tissue and spermatogenic cells.

Results

Testis transcriptome profiling identified 6477 DEGs (2919 upregulated and 3558 downregulated) between cattleyak and yak. Further analysis revealed that the marker genes and apoptosis regulatory genes for undifferentiated spermatogonia were upregulated, while the genes for differentiation maintenance were downregulated in cattleyak. A majority of DEGs associated with mitotic checkpoint, and cell cycle progression were downregulated in cattleyak during spermatogonial mitosis. Furthermore, almost all DEGs related to synaptonemal complex assembly, and meiotic progression presented no sign of expression in cattleyak. Even worse, dozens of genes involved in acrosome formation, and flagellar development were dominantly downregulated in cattleyak.

Conclusion

DEGs indicated that spermatogenic arrest of cattleyak may originate from the differentiation stage of spermatogonial stem cells and be aggravated during spermatogonial mitosis and spermatocyte meiosis, which contributes to the scarcely presented sperms in cattleyak.

Nexin-Dynein regulatory complex component DRC7 but not FBXL13 is required for sperm flagellum formation and male fertility in mice

Flagella and cilia are evolutionarily conserved cellular organelles. Abnormal formation or motility of these organelles in humans causes several syndromic diseases termed ciliopathies. The central component of flagella and cilia is the axoneme that is composed of the ‘9+2’ microtubule arrangement, dynein arms, radial spokes, and the Nexin-Dynein Regulatory Complex (N-DRC). The N-DRC is localized between doublet microtubules and has been extensively studied in the unicellular flagellate Chlamydomonas. Recently, it has been reported that TCTE1 (DRC5), a component of the N-DRC, is essential for proper sperm motility and male fertility in mice. Further, TCTE1 has been shown to interact with FBXL13 (DRC6) and DRC7; however, functional roles of FBXL13 and DRC7 in mammals have not been elucidated. Here we show that Fbxl13 and Drc7 expression are testes-enriched in mice. Although Fbxl13 knockout (KO) mice did not show any obvious phenotypes, Drc7 KO male mice were infertile due to their short immotile spermatozoa. In Drc7 KO spermatids, the axoneme is disorganized and the ‘9+2’ microtubule arrangement was difficult to detect. Further, other N-DRC components fail to incorporate into the flagellum without DRC7. These results indicate that Drc7, but not Fbxl13, is essential for the correct assembly of the N-DRC and flagella.

In recent years, almost one in six couples face infertility, and nearly 50% of cases are attributed to male factors. It has been shown that approximately 15% of male infertility is caused by genetic factors. The conditions of male infertility mainly include spermatozoa with abnormal morphology (teratozoospermia), reduced sperm motility (asthenozoospermia), and no or low sperm count (azoospermia). Multiple morphological abnormalities of the sperm flagella (MMAF) are characterized as asthenoteratozoospermia, which is a condition with abnormal sperm tail morphology, including absent, coiled, bent, or short tails. Sperm tails are formed during spermiogenesis; however, the mechanism that govern tail formation remains unclear. Here we mutated Fbxl13 and Drc7, two genes with strong expression in mouse testis and which have been shown to be important for flagellum formation and regulation in other systems. Deletion of Drc7 leads to aberrant tail formation in mouse spermatozoa that phenocopies patients with MMAF, while deletion of Fbxl13 has no observable effect on sperm function. Our results identified DRC7 as an important factor for sperm flagellum formation.

Microtubular Dysfunction and Male Infertility

Microtubules are the prime component of the cytoskeleton along with microfilaments. Being vital for organelle transport and cellular divisions during spermatogenesis and sperm motility process, microtubules ascertain functional capacity of sperm. Also, microtubule based structures such as axoneme and manchette are crucial for sperm head and tail formation. This review (a) presents a concise, yet detailed structural overview of the microtubules, (b) analyses the role of microtubule structures in various male reproductive functions, and (c) presents the association of microtubular dysfunctions with male infertility. Considering the immense importance of microtubule structures in the formation and maintenance of physiological functions of sperm cells, this review serves as a scientific trigger in stimulating further male infertility research in this direction.

RSPH6A is required for sperm flagellum formation and male fertility in mice

The flagellum is an evolutionarily conserved appendage used for sensing and locomotion. Its backbone is the axoneme and a component of the axoneme is the radial spoke (RS), a protein complex implicated in flagellar motility regulation. Numerous diseases occur if the axoneme is improperly formed, such as primary ciliary dyskinesia (PCD) and infertility. Radial spoke head 6 homolog A (RSPH6A) is an ortholog of Chlamydomonas RSP6 in the RS head and is evolutionarily conserved. While some RS head proteins have been linked to PCD, little is known about RSPH6A. Here, we show that mouse RSPH6A is testis-enriched and localized in the flagellum. Rsph6a knockout (KO) male mice are infertile as a result of their short immotile spermatozoa. Observation of the KO testis indicates that the axoneme can elongate but is disrupted before accessory structures are formed. Manchette removal is also impaired in the KO testis. Further, RSPH9, another radial spoke protein, disappeared in the Rsph6a KO flagella. These data indicate that RSPH6A is essential for sperm flagellar assembly and male fertility in mice.This article has an associated First Person interview with the first author of the paper.

FineMAV: prioritizing candidate genetic variants driving local adaptations in human populations

We present a new method, Fine-Mapping of Adaptive Variation (FineMAV), which combines population differentiation, derived allele frequency, and molecular functionality to prioritize positively selected candidate variants for functional follow-up. We calibrate and test FineMAV using eight experimentally validated "gold standard" positively selected variants and simulations. FineMAV has good sensitivity and a low false discovery rate. Applying FineMAV to the 1000 Genomes Project Phase 3 SNP dataset, we report many novel selected variants, including ones in TGM3 and PRSS53 associated with hair phenotypes that we validate using available independent data. FineMAV is widely applicable to sequence data from both human and other species.

Detection of heterozygous mutation in hook microtubule-tethering protein 1 in three patients with decapitated and decaudated spermatozoa syndrome

BACKGROUND

The mechanism of intramanchette transport is crucial to the transformation of sperm tail and the nuclear condensation during spermiogenesis. Although few dysfunctional proteins could result in abnormal junction between the head and tail of spermatozoon, little is known about the genetic cues in this process.

OBJECTIVE

Based on patients with severe decapitated and decaudated spermatozoa (DDS) syndrome, the study aimed to validate whether new mutation exists on their Hook microtubule-tethering protein 1 (HOOK1) genes and follow their results of assisted reproduction treatment (ART).

METHODS

7 severe teratozoospermia patients with DDS (proportion >95%) and three relative members in one pedigree were collected to sequence the whole genomic DNA. The fertilisation rates (FRs) of these patients were followed. Morphological observation and interspecies intracytoplasmic sperm injection (ICSI) assays were applied.

RESULTS

A novel missense mutation of A to G (p.Q286R) in patients with DDS (n=3/7) was found in the HOOK1 gene, which was inherited from the mother in one patient. This variant was absent in 160 fertile population-matched control individuals. Morphological observation showed that almost all the DDS broke into decaudated heads and headless tails at the implantation fossa or the basal plate. The clinical studies indicated that the mutation might cause reduced FRs on both ART (FR=18.07%) and interspecies ICSI (FR=16.98%).

CONCLUSIONS

An unreported mutation in HOOK1 gene was identified, which might be responsible to some patients with DDS. Further studies need to uncover the molecular mechanism of spermiogenesis for genomic therapy.

Katanin-like 2 (KATNAL2) functions in multiple aspects of haploid male germ cell development in the mouse

The katanin microtubule-severing proteins are essential regulators of microtubule dynamics in a diverse range of species. Here we have defined critical roles for the poorly characterised katanin protein KATNAL2 in multiple aspects of spermatogenesis: the initiation of sperm tail growth from the basal body, sperm head shaping via the manchette, acrosome attachment, and ultimately sperm release. We present data suggesting that depending on context, KATNAL2 can partner with the regulatory protein KATNB1 or act autonomously. Moreover, our data indicate KATNAL2 may regulate δ- and ε-tubulin rather than classical α-β-tubulin microtubule polymers, suggesting the katanin family has a greater diversity of function than previously realised. Together with our previous research, showing the essential requirement of katanin proteins KATNAL1 and KATNB1 during spermatogenesis, our data supports the concept that in higher order species the presence of multiple katanins has allowed for subspecialisation of function within complex cellular settings such as the seminiferous epithelium.

Male infertility affects one in twenty men of reproductive age in western countries. Despite this, the biochemical basis of common defects, including reduced sperm count and abnormal sperm structure and function, remains poorly defined. Microtubules are cellular “scaffolds” that serve critical roles in all cells, including developing male germ cells wherein they facilitate mitosis and meiosis (cell division), sperm head remodelling and sperm tail formation. The precise regulation of microtubule number, length and movement is thus, essential for male fertility. Within this manuscript, we have used spermatogenesis to define the function of the putative microtubule-severing protein katanin-like 2 (KATNAL2). We show that mice with compromised KATNAL2 function are male sterile as a consequence of defects in the structural remodelling of germ cells. Notably, we show the function of microtubule-based structures involved in sperm head shaping and tail formation are disrupted. Further, we show for the first time, that KATNAL2 can function both independently or in concert with the katanin regulatory protein KATNB1 and that it can target the poorly characterized tubulin subunits delta and epsilon. Our research has immediate relevance to the origins of human male infertility and provides novel insights into aspects of microtubule regulation relevant to numerous tissues and species.

LRGUK1 is part of a multiprotein complex required for manchette function and male fertility

Infertility occurs in 1 in 20 young men and is idiopathic in origin in most. We have reported that the leucine-rich repeat (LRR) and guanylate kinase-like domain containing, isoform (LRGUK)-1 is essential for sperm head shaping, via the manchette, and the initiation of sperm tail growth from the centriole/basal body, and thus, male fertility. Within this study we have used a yeast 2-hybrid screen of an adult testis library to identify LRGUK1-binding partners, which were then validated with a range of techniques. The data indicate that LRGUK1 likely achieves its function in partnership with members of the HOOK family of proteins (HOOK-1-3), Rab3-interacting molecule binding protein (RIMBP)-3 and kinesin light chain (KLC)-3, all of which are associated with intracellular protein transport as cargo adaptor proteins and are localized to the manchette. LRGUK1 consists of 3 domains; an LRR, a guanylate kinase (GUK)-like and an unnamed domain. In the present study, we showed that the GUK-like domain is essential for binding to HOOK2 and RIMBP3, and the LRR domain is essential for binding to KLC3. These findings establish LRGUK1 as a key component of a multiprotein complex with an essential role in microtubule dynamics within haploid male germ cells.-Okuda, H., DeBoer, K., O'Connor, A. E., Merriner, D. J., Jamsai, D., O'Bryan, M. K. LRGUK1 is part of a multiprotein complex required for manchette function and male fertility.

The control of male fertility by spermatid-specific factors: searching for contraceptive targets from spermatozoon's head to tail

Male infertility due to abnormal spermatozoa has been reported in both animals and humans, but its pathogenic causes, including genetic abnormalities, remain largely unknown. On the other hand, contraceptive options for men are limited, and a specific, reversible and safe method of male contraception has been a long-standing quest in medicine. Some progress has recently been made in exploring the effects of spermatid-specifical genetic factors in controlling male fertility. A comprehensive search of PubMed for articles and reviews published in English before July 2016 was carried out using the search terms 'spermiogenesis failure', 'globozoospermia', 'spermatid-specific', 'acrosome', 'infertile', 'manchette', 'sperm connecting piece', 'sperm annulus', 'sperm ADAMs', 'flagellar abnormalities', 'sperm motility loss', 'sperm ion exchanger' and 'contraceptive targets'. Importantly, we have opted to focus on articles regarding spermatid-specific factors. Genetic studies to define the structure and physiology of sperm have shown that spermatozoa appear to be one of the most promising contraceptive targets. Here we summarize how these spermatid-specific factors regulate spermiogenesis and categorize them according to their localization and function from spermatid head to tail (e.g., acrosome, manchette, head-tail conjunction, annulus, principal piece of tail). In addition, we emphatically introduce small-molecule contraceptives, such as BRDT and PPP3CC/PPP3R2, which are currently being developed to target spermatogenic-specific proteins. We suggest that blocking the differentiation of haploid germ cells, which rarely affects early spermatogenic cell types and the testicular microenvironment, is a better choice than spermatogenic-specific proteins. The studies described here provide valuable information regarding the genetic and molecular defects causing male mouse infertility to improve our understanding of the importance of spermatid-specific factors in controlling fertility. Although a male contraceptive 'pill' is still many years away, research into the production of new small-molecule contraceptives targeting spermatid-specific proteins is the right avenue.

Formation and function of the manchette and flagellum during spermatogenesis

The last phase of spermatogenesis involves spermatid elongation (spermiogenesis), where the nucleus is remodeled by chromatin condensation, the excess cytoplasm is removed and the acrosome and sperm tail are formed. Protein transport during spermatid elongation is required for correct formation of the sperm tail and acrosome and shaping of the head. Two microtubular-based protein delivery platforms transport proteins to the developing head and tail: the manchette and the sperm tail axoneme. The manchette is a transient skirt-like structure surrounding the elongating spermatid head and is only present during spermatid elongation. In this review, we consider current understanding of the assembly, disassembly and function of the manchette and the roles of these processes in spermatid head shaping and sperm tail formation. Recent studies have shown that at least some of the structural proteins of the sperm tail are transported through the intra-manchette transport to the basal body at the base of the developing sperm tail and through the intra-flagellar transport to the construction site in the flagellum. This review focuses on the microtubule-based mechanisms involved and the consequences of their disruption in spermatid elongation.