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ELife Apr 2023The manchette is a transient and unique structure present in elongating spermatids and required for proper differentiation of the germ cells during spermatogenesis....
The manchette is a transient and unique structure present in elongating spermatids and required for proper differentiation of the germ cells during spermatogenesis. Previous work indicated that the MEIG1/PACRG complex locates in the manchette and is involved in the transport of cargos, such as SPAG16L, to build the sperm flagellum. Here, using co-immunoprecipitation and pull-down approaches in various cell systems, we established that DNALI1, an axonemal component originally cloned from , recruits and stabilizes PACRG and we confirm in vivo, the co-localization of DNALI1 and PACRG in the manchette by immunofluorescence of elongating murine spermatids. We next generated mice with a specific deficiency of DNALI1 in male germ cells, and observed a dramatic reduction of the sperm cells, which results in male infertility. In addition, we observed that the majority of the sperm cells exhibited abnormal morphology including misshapen heads, bent tails, enlarged midpiece, discontinuous accessory structure, emphasizing the importance of DNALI1 in sperm differentiation. Examination of testis histology confirmed impaired spermiogenesis in the mutant mice. Importantly, while testicular levels of MEIG1, PACRG, and SPAG16L proteins were unchanged in the mutant mice, their localization within the manchette was greatly affected, indicating that DNALI1 is required for the formation of the MEIG1/PACRG complex within the manchette. Interestingly, in contrast to MEIG1 and PACRG-deficient mice, the DNALI1-deficient mice also showed impaired sperm spermiation/individualization, suggesting additional functions beyond its involvement in the manchette structure. Overall, our work identifies DNALI1 as a protein required for sperm development.
Topics: Male; Mice; Animals; Sperm Tail; Seeds; Spermatogenesis; Proteins; Spermatids; Testis; Nuclear Proteins; Phosphoproteins; Cell Cycle Proteins
PubMed: 37083624
DOI: 10.7554/eLife.79620 -
BioRxiv : the Preprint Server For... Oct 2023Mammalian sperm delve into the female reproductive tract to fertilize the female gamete. The available information about how sperm regulate their motility during the...
UNLABELLED
Mammalian sperm delve into the female reproductive tract to fertilize the female gamete. The available information about how sperm regulate their motility during the final journey to the fertilization site is extremely limited. In this work, we investigated the structural and functional changes in the sperm flagellum after acrosomal exocytosis and during the interaction with the eggs. The evidence demonstrates that the double helix actin network surrounding the mitochondrial sheath of the midpiece undergoes structural changes prior to the motility cessation. This structural modification is accompanied by a decrease in diameter of the midpiece and is driven by intracellular calcium changes that occur concomitant with a reorganization of the actin helicoidal cortex. Although midpiece contraction may occur in a subset of cells that undergo acrosomal exocytosis, live-cell imaging during in vitro fertilization showed that the midpiece contraction is required for motility cessation after fusion is initiated. These findings provide the first evidence of the F-actin network's role in regulating sperm motility, adapting its function to meet specific cellular requirements during fertilization, and highlighting the broader significance of understanding sperm motility.
SIGNIFICANT STATEMENT
In this work, we demonstrate that the helical structure of polymerized actin in the flagellum undergoes a rearrangement at the time of sperm-egg fusion. This process is driven by intracellular calcium and promotes a decrease in the sperm midpiece diameter as well as the arrest in motility, which is observed after the fusion process is initiated.
PubMed: 37904966
DOI: 10.1101/2023.06.22.546073 -
Journal of Translational Medicine Mar 2024Mitochondria produce adenosine triphosphate through respiratory activities to power sperm differentiation and motility, and decreased mitochondrial respiratory activity...
BACKGROUND
Mitochondria produce adenosine triphosphate through respiratory activities to power sperm differentiation and motility, and decreased mitochondrial respiratory activity can result in poor sperm motility and asthenospermia. The mitochondrial sheath is a component of the mid-piece of the sperm flagellum, and dysfunction of the sheath can reduce sperm motility and cause male infertility. The membrane occupation and recognition nexus-motif protein 2 (MORN2) is testis enriched in mice, and the MORN motif was reported to play a role in the regulation of bioelectrical signal homeostasis in cardiomyocytes.
METHODS
We generated Morn2 mice using CRISPR/Cas9 and evaluated the potential functions of MORN2 in spermiogenesis through histological analysis, fertility examination, RT-PCR, CASA, immunofluorescence, TUNEL, electron microscopy analysis, mitochondrial energy metabolism analysis, etc. RESULTS: The Morn2 mice were infertile, and their sperm showed severe motility defects. Morn2 sperm also had abnormal morphology characterized by bent heads, aberrant mitochondrial sheath formation, lower mitochondrial membrane potential, higher levels of reactive oxygen species, and decreased mitochondrial respiratory activity.
CONCLUSIONS
Our study demonstrates that MORN2 is essential for male fertility and indicates that MORN2 functions in mitochondrial sheath formation and regulates mitochondrial respiratory activity.
Topics: Animals; Male; Mice; Energy Metabolism; Fertility; Mitochondria; Semen; Sperm Motility
PubMed: 38443933
DOI: 10.1186/s12967-024-05010-3 -
Andrology Nov 2023This review surveys the causes and consequences of DNA damage in the male germ line from spermatogonial stem cells to fully differentiated spermatozoa. Within the stem... (Review)
Review
This review surveys the causes and consequences of DNA damage in the male germ line from spermatogonial stem cells to fully differentiated spermatozoa. Within the stem cell population, DNA integrity is well maintained as a result of excellent DNA surveillance and repair; however, a progressive increase in background mutation rates does occur with paternal age possibly as a result of aberrant DNA repair as well as replication error. Once a germ cell has committed to spermatogenesis, it responds to genetic damage via a range of DNA repair pathways or, if this process fails, by the induction of apoptosis. When fully-differentiated spermatozoa are stressed, they also activate a truncated intrinsic apoptotic pathway which results in the activation of nucleases in the mitochondria and cytoplasm; however, the physical architecture of these cells prevents these enzymes from translocating to the nucleus to induce DNA fragmentation. Conversely, hydrogen peroxide released from the sperm midpiece during apoptosis is able to penetrate the nucleus and induce DNA damage. The base excision repair pathway responds to such damage by cleaving oxidized bases from the DNA, leaving abasic sites that are alkali-labile and readily detected with the comet assay. As levels of oxidative stress increase and these cells enter the perimortem, topoisomerase integrated into the sperm chromatin becomes activated by SUMOylation. Such activation may initially facilitate DNA repair by reannealing double strand breaks but ultimately prepares the DNA for destruction by nucleases released from the male reproductive tract. The abasic sites and oxidized base lesions found in live spermatozoa are mutagenic and may increase the mutational load carried by the offspring, particularly in the context of assisted conception. A variety of strategies are described for managing patients expressing high levels of DNA damage in their spermatozoa, to reduce the risks such lesions might pose to offspring health.
Topics: Male; Humans; Semen; Spermatozoa; Testis; DNA Damage; DNA
PubMed: 36604857
DOI: 10.1111/andr.13375 -
International Journal of Infectious... Nov 2021The effects of human papillomavirus (HPV) infection on male reproductive parameters are currently a matter of controversy. In order to clarify the issue in Japanese...
OBJECTIVES
The effects of human papillomavirus (HPV) infection on male reproductive parameters are currently a matter of controversy. In order to clarify the issue in Japanese infertile men, the prevalence and localization of HPV in semen, sperm parameters, and superoxide dismutase (SOD) activity in seminal plasma were examined in 216 Japanese infertile men.
METHODS
DNA was extracted from liquid-based cytological semen samples. The β-globin gene was amplified by polymerase chain reaction (PCR), and HPV-DNA was amplified using nested PCR with MY09/MY11 as outer primers and GP5+/GP6+ as inner primers. HPV genotyping was performed in the HPV-positive samples. In addition, SOD levels in seminal plasma were analysed quantitatively. In-situ hybridization (ISH) was performed to localize HPV-DNA in sperm from HPV-positive samples.
RESULTS
Any-risk and high-risk prevalence rates of HPV in semen were 12.5% and 6.9%, respectively. No significant difference in the prevalence of HPV was observed between azoospermic and non-azoospermic subjects. Among non-azoospermic patients, those with HPV detected in semen had significantly lower sperm motility and concentration compared with subjects without HPV detected in semen. SOD levels in seminal plasma were significantly higher in HPV-positive patients compared with HPV-negative patients. ISH analysis of HPV-positive samples revealed that HPV-DNA was localized to the head and mid-piece of sperm. HPV-DNA was present in the sperm of young infertile men.
CONCLUSION
HPV infection of sperm was associated with reduced sperm motility and concentration, and resulted in an increase in seminal SOD activity.
Topics: Alphapapillomavirus; Humans; Japan; Male; Papillomaviridae; Papillomavirus Infections; Sperm Motility; Spermatozoa
PubMed: 34547493
DOI: 10.1016/j.ijid.2021.09.029 -
Frontiers in Cell and Developmental... 2022The normal functioning of sperm cells requires cytochrome c in the redox balanced forms: reduced and oxidized. The oxidized form of cytochrome c is localized in the...
The normal functioning of sperm cells requires cytochrome c in the redox balanced forms: reduced and oxidized. The oxidized form of cytochrome c is localized in the mitochondrial intermembrane space and is a part of the electron transport chain. This ensures that electron shuttling between the complex III, cytochrome c, and complex IV can occur leading to controlled effective oxidative phosphorylation (respiration) and ATP production needed for most steps in spermatozoal maturation, motility, hyperactivation and fertilization. We studied the biochemical composition of specific organelles in sperm cells by Raman imaging. The structures of the head consisting of the nucleus and acrosome, the midpiece representing mitochondria, and the tail characterized by the sperm axoneme surrounded by outer dense fiber and covered by the membrane were measured. Metabolic biochemical analysis of mitochondria, head and tail of sperm cells, and seminal plasma by using Raman imaging combined with chemometric classification method of Cluster Analysis has been obtained. Our results show that cytochrome c, which is a key protein that is needed to maintain life (respiration) and cell death (apoptosis), is located in sperm mitochondria in the oxidized or reduced form of the heme group. This work demonstrated that an application of Raman micro-spectroscopy can be extended to monitoring the redox state of mitochondrial cytochrome c in sperm cells.
PubMed: 36506104
DOI: 10.3389/fcell.2022.983993 -
The Journal of Cell Biology Mar 2024Proper compartmentalization of the sperm flagellum is essential for fertility. The annulus is a septin-based ring that demarcates the midpiece (MP) and the principal...
Proper compartmentalization of the sperm flagellum is essential for fertility. The annulus is a septin-based ring that demarcates the midpiece (MP) and the principal piece (PP). It is assembled at the flagellar base, migrates caudally, and halts upon arriving at the PP. However, the mechanisms governing annulus positioning remain unknown. We report that a Chibby3 (Cby3)/Cby1-interacting BAR domain-containing 1 (ciBAR1) complex is required for this process. Ablation of either gene in mice results in male fertility defects, caused by kinked sperm flagella with the annulus mispositioned in the PP. Cby3 and ciBAR1 interact and colocalize to the annulus near the curved membrane invagination at the flagellar pocket. In the absence of Cby3, periannular membranes appear to be deformed, allowing the annulus to migrate over the fibrous sheath into the PP. Collectively, our results suggest that the Cby3/ciBAR1 complex regulates local membrane properties to position the annulus at the MP/PP junction.
Topics: Animals; Male; Mice; Cilia; Cytoskeleton; Semen; Sperm Tail; Spermatogenesis; Nuclear Proteins; Carrier Proteins
PubMed: 38197861
DOI: 10.1083/jcb.202307147 -
Reproduction & Fertility Nov 2022Seminal plasma contains extracellular vesicles (EVs) that vehicle RNA, proteins, and other molecules able to influence the biological function of sperm. The aim of this...
Seminal plasma contains extracellular vesicles (EVs) that vehicle RNA, proteins, and other molecules able to influence the biological function of sperm. The aim of this study was to improve the fertilizing capacity of male gametes of low-fertility bulls using EVs isolated by ultracentrifugation from the seminal plasma of a bull of proven fertility. After dose-response curve, 10×106 sperm of low-fertility bulls were co-incubated for an hour with 400×106 EVs/ml. In addition, it has been verified that the incorporation of EVs, which takes place in the sperm midpiece, is maintained for 5 hours and even after cryopreservation. Subsequently, the spermatozoa of low-fertility bulls, with EVs incorporated, were used for the in vitro production of embryos. The rate of blastocyst at seventh day yield in vitro, with the use of sperm with EVs incorporated, increased by about twice the yield obtained with the same sperm in the absence of EVs: bulls having an average embryonic yield of 6.41±1.48%, 10.32±4.34% and 10.92±0.95% improved their yield to 21.21±1.99%, 22.17±6.09% and 19.99±5.78%, respectively (P<0.05). These encouraging results suggest that it might be possible to keep breeding bulls with poor fertility. Further studies will be needed to evaluate the in vivo fertility of sperm treated with EVs and understand how the content of EVs is involve in the sperm-vesicle interaction and in the improved sperm performance.
PubMed: 36374278
DOI: 10.1530/RAF-22-0037 -
Human Mutation Dec 2022Asthenoteratozoospermia is the primary cause of infertility in humans. However, the genetic etiology remains largely unknown for those suffering from severe...
Asthenoteratozoospermia is the primary cause of infertility in humans. However, the genetic etiology remains largely unknown for those suffering from severe asthenoteratozoospermia caused by thin midpiece defects. In this study, we identified two biallelic loss-of-function variants of SEPTIN4 (previously SEPT4) (Patient 1: c.A721T, p.R241* and Patient 2: c.C205T, p.R69*) in two unrelated individuals from two consanguineous Chinese families. SEPT4 is a conserved annulus protein that is critical for male fertility and the structural integrity of the sperm midpiece in mice. SEPT4 mutations disrupted the formation of SEPT-based annulus and localization of SEPTIN subunits in sperms from patients. The ultrastructural analysis demonstrated striking thin midpiece spermatozoa defects owing to annulus loss and disorganized mitochondrial sheath. Immunofluorescence and immunoblotting analyses of the mitochondrial sheath proteins TOMM20 and HSP60 further indicated that the distribution and abundance of mitochondria were impaired in men harboring biallelic SEPT4 variants. Additionally, we found that the precise localization of SLC26A8, a testis-specific anion transporter that colocalizes with SEPT4 at the sperm annulus, was missing without SEPT4. Moreover, the patient achieved a good pregnancy outcome following intracytoplasmic sperm injection. Overall, our study demonstrated for the first time that SEPT4 variants that induced thin midpiece spermatozoa defects were directly associated with human asthenoteratozoospermia.
Topics: Female; Humans; Male; Pregnancy; Asthenozoospermia; Infertility, Male; Proteins; Semen; Sperm Tail; Spermatozoa; Septins
PubMed: 36135717
DOI: 10.1002/humu.24475 -
Scientific Data Jan 2022Sperm are the most morphologically variable cell type known, despite performing the same functional role of fertilizing eggs across all sexually reproducing species....
Sperm are the most morphologically variable cell type known, despite performing the same functional role of fertilizing eggs across all sexually reproducing species. Sperm morphology commonly varies among individuals, populations, closely related species, and across animal phyla. Sperm morphology has long been used as a tool for placing species in a phylogenetic context and a range of selective forces are hypothesized to influence sperm evolution and diversification. However, we currently lack robust examinations of macroevolutionary (i.e. across phyla) patterns of sperm evolution, due largely to the challenges of comparing sperm morphological data across the animal tree of life. Here we describe the SpermTree database, which currently represents 5,675 morphological descriptions of sperm morphology from 4,705 unique species from 27 animal phyla. This dataset includes measurements of sperm head, midpiece, flagellum and total length, the latter of which spans four orders of magnitude. All entries in the dataset are matched to currently accepted scientific names in taxonomic databases, facilitating the use of these data in analyses examining sperm evolution in animals.
Topics: Animals; Databases, Factual; Male; Phylogeny; Spermatozoa
PubMed: 35102160
DOI: 10.1038/s41597-022-01131-w