RESUMO
Following the fertilization of an egg by a single sperm, the egg coat or zona pellucida (ZP) hardens and polyspermy is irreversibly blocked. These events are associated with the cleavage of the N-terminal region (NTR) of glycoprotein ZP2, a major subunit of ZP filaments. ZP2 processing is thought to inactivate sperm binding to the ZP, but its molecular consequences and connection with ZP hardening are unknown. Biochemical and structural studies show that cleavage of ZP2 triggers its oligomerization. Moreover, the structure of a native vertebrate egg coat filament, combined with AlphaFold predictions of human ZP polymers, reveals that two protofilaments consisting of type I (ZP3) and type II (ZP1/ZP2/ZP4) components interlock into a left-handed double helix from which the NTRs of type II subunits protrude. Together, these data suggest that oligomerization of cleaved ZP2 NTRs extensively cross-links ZP filaments, rigidifying the egg coat and making it physically impenetrable to sperm.
Assuntos
Glicoproteínas da Zona Pelúcida , Humanos , Masculino , Sêmen , Espermatozoides/química , Espermatozoides/metabolismo , Zona Pelúcida/química , Zona Pelúcida/metabolismo , Glicoproteínas da Zona Pelúcida/química , Glicoproteínas da Zona Pelúcida/metabolismo , Óvulo/química , Óvulo/metabolismo , FemininoRESUMO
Sperm motility is crucial for successful fertilization. Highly decorated doublet microtubules (DMTs) form the sperm tail skeleton, which propels the movement of spermatozoa. Using cryo-electron microscopy (cryo-EM) and artificial intelligence (AI)-based modeling, we determined the structures of mouse and human sperm DMTs and built an atomic model of the 48-nm repeat of the mouse sperm DMT. Our analysis revealed 47 DMT-associated proteins, including 45 microtubule inner proteins (MIPs). We identified 10 sperm-specific MIPs, including seven classes of Tektin5 in the lumen of the A tubule and FAM166 family members that bind the intra-tubulin interfaces. Interestingly, the human sperm DMT lacks some MIPs compared with the mouse sperm DMT. We also discovered variants in 10 distinct MIPs associated with a subtype of asthenozoospermia characterized by impaired sperm motility without evident morphological abnormalities. Our study highlights the conservation and tissue/species specificity of DMTs and expands the genetic spectrum of male infertility.
Assuntos
Inteligência Artificial , Infertilidade Masculina , Masculino , Humanos , Microscopia Crioeletrônica , Motilidade dos Espermatozoides/genética , Sêmen , Espermatozoides , Microtúbulos/metabolismo , Cauda do Espermatozoide/química , Cauda do Espermatozoide/metabolismo , Proteínas dos Microtúbulos/química , Infertilidade Masculina/genética , Infertilidade Masculina/metabolismoRESUMO
Sperm motility is crucial to reproductive success in sexually reproducing organisms. Impaired sperm movement causes male infertility, which is increasing globally. Sperm are powered by a microtubule-based molecular machine-the axoneme-but it is unclear how axonemal microtubules are ornamented to support motility in diverse fertilization environments. Here, we present high-resolution structures of native axonemal doublet microtubules (DMTs) from sea urchin and bovine sperm, representing external and internal fertilizers. We identify >60 proteins decorating sperm DMTs; at least 15 are sperm associated and 16 are linked to infertility. By comparing DMTs across species and cell types, we define core microtubule inner proteins (MIPs) and analyze evolution of the tektin bundle. We identify conserved axonemal microtubule-associated proteins (MAPs) with unique tubulin-binding modes. Additionally, we identify a testis-specific serine/threonine kinase that links DMTs to outer dense fibers in mammalian sperm. Our study provides structural foundations for understanding sperm evolution, motility, and dysfunction at a molecular level.
Assuntos
Motilidade dos Espermatozoides , Cauda do Espermatozoide , Masculino , Animais , Bovinos , Cauda do Espermatozoide/química , Cauda do Espermatozoide/metabolismo , Sêmen , Microtúbulos/metabolismo , Axonema/química , Espermatozoides , MamíferosRESUMO
To understand the molecular mechanisms of cellular pathways, contemporary workflows typically require multiple techniques to identify proteins, track their localization, and determine their structures in vitro. Here, we combined cellular cryoelectron tomography (cryo-ET) and AlphaFold2 modeling to address these questions and understand how mammalian sperm are built in situ. Our cellular cryo-ET and subtomogram averaging provided 6.0-Å reconstructions of axonemal microtubule structures. The well-resolved tertiary structures allowed us to unbiasedly match sperm-specific densities with 21,615 AlphaFold2-predicted protein models of the mouse proteome. We identified Tektin 5, CCDC105, and SPACA9 as novel microtubule-associated proteins. These proteins form an extensive interaction network crosslinking the lumen of axonemal doublet microtubules, suggesting their roles in modulating the mechanical properties of the filaments. Indeed, Tekt5 -/- sperm possess more deformed flagella with 180° bends. Together, our studies presented a cellular visual proteomics workflow and shed light on the in vivo functions of Tektin 5.
Assuntos
Proteoma , Espermatozoides , Animais , Masculino , Camundongos , Axonema/química , Microscopia Crioeletrônica/métodos , Flagelos/metabolismo , Microtúbulos/metabolismo , Sêmen , Espermatozoides/química , Proteoma/análiseRESUMO
Throughout development and aging, human cells accumulate mutations resulting in genomic mosaicism and genetic diversity at the cellular level. Mosaic mutations present in the gonads can affect both the individual and the offspring and subsequent generations. Here, we explore patterns and temporal stability of clonal mosaic mutations in male gonads by sequencing ejaculated sperm. Through 300× whole-genome sequencing of blood and sperm from healthy men, we find each ejaculate carries on average 33.3 ± 12.1 (mean ± SD) clonal mosaic variants, nearly all of which are detected in serial sampling, with the majority absent from sampled somal tissues. Their temporal stability and mutational signature suggest origins during embryonic development from a largely immutable stem cell niche. Clonal mosaicism likely contributes a transmissible, predicted pathogenic exonic variant for 1 in 15 men, representing a life-long threat of transmission for these individuals and a significant burden on human population health.
Assuntos
Crescimento e Desenvolvimento , Mosaicismo , Espermatozoides/metabolismo , Adolescente , Envelhecimento/sangue , Alelos , Células Clonais , Estudos de Coortes , Humanos , Masculino , Modelos Biológicos , Mutação/genética , Fatores de Risco , Fatores de Tempo , Adulto JovemRESUMO
Fertilization is a multistep process that culminates in the fusion of sperm and egg, thus marking the beginning of a new organism in sexually reproducing species. Despite its importance for reproduction, the molecular mechanisms that regulate this singular event, particularly sperm-egg fusion, have remained mysterious for many decades. Here, we summarize our current molecular understanding of sperm-egg interaction, focusing mainly on mammalian fertilization. Given the fundamental importance of sperm-egg fusion yet the lack of knowledge of this process in vertebrates, we discuss hallmarks and emerging themes of cell fusion by drawing from well-studied examples such as viral entry, placenta formation, and muscle development. We conclude by identifying open questions and exciting avenues for future studies in gamete fusion.
Assuntos
Fertilização , Interações Espermatozoide-Óvulo , Animais , Masculino , Mamíferos , Reprodução , Interações Espermatozoide-Óvulo/fisiologia , Espermatozoides/fisiologiaRESUMO
Physiology and metabolism are often sexually dimorphic, but the underlying mechanisms remain incompletely understood. Here, we use the intestine of Drosophila melanogaster to investigate how gut-derived signals contribute to sex differences in whole-body physiology. We find that carbohydrate handling is male-biased in a specific portion of the intestine. In contrast to known sexual dimorphisms in invertebrates, the sex differences in intestinal carbohydrate metabolism are extrinsically controlled by the adjacent male gonad, which activates JAK-STAT signaling in enterocytes within this intestinal portion. Sex reversal experiments establish roles for this male-biased intestinal metabolic state in controlling food intake and sperm production through gut-derived citrate. Our work uncovers a male gonad-gut axis coupling diet and sperm production, revealing that metabolic communication across organs is physiologically important. The instructive role of citrate in inter-organ communication might be significant in more biological contexts than previously recognized.
Assuntos
Metabolismo dos Carboidratos/fisiologia , Drosophila melanogaster/metabolismo , Ingestão de Alimentos/fisiologia , Mucosa Intestinal/metabolismo , Caracteres Sexuais , Maturação do Esperma/fisiologia , Animais , Ácido Cítrico/metabolismo , Proteínas de Drosophila/metabolismo , Feminino , Expressão Gênica , Janus Quinases/metabolismo , Masculino , RNA-Seq , Fatores de Transcrição STAT/metabolismo , Transdução de Sinais , Açúcares/metabolismo , Testículo/metabolismoRESUMO
Varying pH of luminal fluid along the female reproductive tract is a physiological cue that modulates sperm motility. CatSper is a sperm-specific, pH-sensitive calcium channel essential for hyperactivated motility and male fertility. Multi-subunit CatSper channel complexes organize linear Ca2+ signaling nanodomains along the sperm tail. Here, we identify EF-hand calcium-binding domain-containing protein 9 (EFCAB9) as a bifunctional, cytoplasmic machine modulating the channel activity and the domain organization of CatSper. Knockout mice studies demonstrate that EFCAB9, in complex with the CatSper subunit, CATSPERζ, is essential for pH-dependent and Ca2+-sensitive activation of the CatSper channel. In the absence of EFCAB9, sperm motility and fertility is compromised, and the linear arrangement of the Ca2+ signaling domains is disrupted. EFCAB9 interacts directly with CATSPERζ in a Ca2+-dependent manner and dissociates at elevated pH. These observations suggest that EFCAB9 is a long-sought, intracellular, pH-dependent Ca2+ sensor that triggers changes in sperm motility.
Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Motilidade dos Espermatozoides/fisiologia , Animais , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Proteínas de Ligação ao Cálcio/fisiologia , Linhagem Celular , Membrana Celular/metabolismo , Fertilidade , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Espermatozoides/metabolismoRESUMO
Recognition between sperm and the egg surface marks the beginning of life in all sexually reproducing organisms. This fundamental biological event depends on the species-specific interaction between rapidly evolving counterpart molecules on the gametes. We report biochemical, crystallographic, and mutational studies of domain repeats 1-3 of invertebrate egg coat protein VERL and their interaction with cognate sperm protein lysin. VERL repeats fold like the functionally essential N-terminal repeat of mammalian sperm receptor ZP2, whose structure is also described here. Whereas sequence-divergent repeat 1 does not bind lysin, repeat 3 binds it non-species specifically via a high-affinity, largely hydrophobic interface. Due to its intermediate binding affinity, repeat 2 selectively interacts with lysin from the same species. Exposure of a highly positively charged surface of VERL-bound lysin suggests that complex formation both disrupts the organization of egg coat filaments and triggers their electrostatic repulsion, thereby opening a hole for sperm penetration and fusion.
Assuntos
Fertilização , Invertebrados/fisiologia , Vertebrados/fisiologia , Sequência de Aminoácidos , Animais , Evolução Biológica , Proteínas do Ovo/química , Proteínas do Ovo/metabolismo , Humanos , Invertebrados/química , Invertebrados/genética , Masculino , Modelos Moleculares , Mucoproteínas/química , Mucoproteínas/metabolismo , Óvulo/química , Óvulo/metabolismo , Alinhamento de Sequência , Especificidade da Espécie , Espermatozoides/química , Espermatozoides/metabolismo , Vertebrados/genética , Difração de Raios X , Glicoproteínas da Zona Pelúcida/química , Glicoproteínas da Zona Pelúcida/metabolismoRESUMO
Despite the numerous sequencing methods available, the diversity in RNA size and chemical modification makes it difficult to capture all RNAs in a cell. We developed a method that combines quasi-random priming with template switching to construct sequencing libraries from RNA molecules of any length and with any type of 3' modifications, allowing for the sequencing of virtually all RNA species. Our ligation-independent detection of all types of RNA (LIDAR) is a simple, effective tool to identify and quantify all classes of coding and non-coding RNAs. With LIDAR, we comprehensively characterized the transcriptomes of mouse embryonic stem cells, neural progenitor cells, mouse tissues, and sperm. LIDAR detected a much larger variety of tRNA-derived RNAs (tDRs) compared with traditional ligation-dependent sequencing methods and uncovered tDRs with blocked 3' ends that had previously escaped detection. Therefore, LIDAR can capture all RNAs in a sample and uncover RNA species with potential regulatory functions.
RESUMO
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 â¼30 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.
Assuntos
Exocitose/fisiologia , Interações Espermatozoide-Óvulo/fisiologia , Espermatozoides/fisiologia , Testículo/citologia , Animais , Evolução Biológica , Humanos , Masculino , Mamíferos/fisiologia , Espermatozoides/citologiaRESUMO
Spermatogonial stem cells (SSCs) are generally characterized by excellent DNA surveillance and repair, resulting in one of the lowest spontaneous mutation rates in the body. However, the barriers to mutagenesis can be overwhelmed under two sets of circumstances. First, replication errors may generate age-dependent mutations that provide the mutant cells with a selective advantage, leading to the clonal expansions responsible for dominant genetic diseases such as Apert syndrome and achondroplasia. The second mechanism centers on the vulnerability of the male germline to oxidative stress and the induction of oxidative DNA damage in spermatozoa. Defective repair of such oxidative damage in the fertilized oocyte results in the creation of mutations in the zygote that can influence the health and well-being of the offspring. A particular hot spot for such oxidative attack on chromosome 15 has been found to align with several mutations responsible for paternally mediated disease, including cancer, psychiatric disorders, and infertility.
Assuntos
Doenças Genéticas Inatas/genética , Mutação/genética , Animais , Cromossomos Humanos Par 15/genética , Dano ao DNA/genética , Humanos , Masculino , Taxa de Mutação , Neoplasias/genética , Oócitos/crescimento & desenvolvimento , Espermatozoides/crescimento & desenvolvimentoRESUMO
The ovarian microenvironment plays a crucial role in ensuring the reproductive success of viviparous teleosts. However, the molecular mechanism underlying the interaction between spermatozoa and the ovarian microenvironment has remained elusive. This study aimed to contribute to a better understanding of this process in black rockfish (Sebastes schlegelii) using integrated multi-omics approaches. The results demonstrated significant upregulation of ovarian complement-related proteins and pattern recognition receptors, along with remodeling of glycans on the surface of spermatozoa at the early spermatozoa-storage stage (1 month after mating). As spermatozoa were stored over time, ovarian complement proteins were progressively repressed by tryptophan and hippurate, indicating a remarkable adaptation of spermatozoa to the ovarian microenvironment. Before fertilization, a notable upregulation of cellular junction proteins was observed. The study revealed that spermatozoa bind to ZPB2a protein through GSTM3 and that ZPB2a promotes spermatozoa survival and movement in a GSTM3-dependent manner. These findings shed light on a key mechanism that influences the dynamics of spermatozoa in the female reproductive tract, providing valuable insights into the molecular networks regulating spermatozoa adaptation and survival in species with internal fertilization.
Assuntos
Ovário , Espermatozoides , Animais , Masculino , Feminino , Espermatozoides/metabolismo , Ovário/metabolismo , Fertilização , Viviparidade não Mamífera , Proteômica , Proteínas de Peixes/metabolismo , Proteínas de Peixes/genética , Peixes/metabolismo , Microambiente Celular , MultiômicaRESUMO
Mitochondria are the powerhouses of many biological processes. During spermatogenesis, post-transcriptional regulation of mitochondrial gene expression is mediated by nuclear-encoded mitochondrial RNA-binding proteins (mtRBPs). We identified AMG-1 as an mtRBP required for reproductive success in Caenorhabditis elegans. amg-1 mutation led to defects in mitochondrial structure and sperm budding, resulting in mitochondria being discarded into residual bodies, which ultimately delayed spermatogenesis in the proximal gonad. In addition, mitochondrial defects triggered the gonadal mitochondrial unfolded protein response and phagocytic clearance to ensure spermatogenesis but ultimately failed to rescue hermaphroditic fertility. These findings reveal a previously undiscovered role for AMG-1 in regulating C. elegans spermatogenesis, in which mitochondrial-damaged sperm prevented the transmission of defective mitochondria to mature sperm by budding and phagocytic clearance, a process which may also exist in the reproductive systems of higher organisms.
Assuntos
Adenosina/análogos & derivados , Proteínas de Caenorhabditis elegans , Doenças Mitocondriais , Animais , Masculino , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Sêmen/metabolismo , Espermatogênese/genética , Mutação/genéticaRESUMO
The epigenetic information present in mammalian gametes and whether it is transmitted to the progeny are relatively unknown. We find that many promoters in mouse sperm are occupied by RNA polymerase II (Pol II) and Mediator. The same promoters are accessible in GV and MII oocytes and preimplantation embryos. Sperm distal ATAC-seq sites containing motifs for various transcription factors are conserved in monkeys and humans. ChIP-seq analyses confirm that Foxa1, ERα, and AR occupy distal enhancers in sperm. Accessible sperm enhancers containing H3.3 and H2A.Z are also accessible in oocytes and preimplantation embryos. Furthermore, their interactions with promoters in the gametes persist during early development. Sperm- or oocyte-specific interactions mediated by CTCF and cohesin are only present in the paternal or maternal chromosomes, respectively, in the zygote and 2-cell stages. These interactions converge in both chromosomes by the 8-cell stage. Thus, mammalian gametes contain complex patterns of 3D interactions that can be transmitted to the zygote after fertilization.
Assuntos
Fator de Ligação a CCCTC/genética , Fator 3-beta Nuclear de Hepatócito/genética , Oócitos/metabolismo , Espermatozoides/metabolismo , Zigoto/metabolismo , Animais , Sequência de Bases , Fator de Ligação a CCCTC/metabolismo , Cromatina/química , Cromatina/metabolismo , Sequência Conservada , Embrião de Mamíferos , Desenvolvimento Embrionário/genética , Elementos Facilitadores Genéticos , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/genética , Receptor beta de Estrogênio/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Fator 3-beta Nuclear de Hepatócito/metabolismo , Humanos , Macaca mulatta , Masculino , Camundongos , Oócitos/citologia , Oócitos/crescimento & desenvolvimento , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Homologia de Sequência do Ácido Nucleico , Espermatozoides/citologia , Espermatozoides/crescimento & desenvolvimento , Dedos de Zinco/genética , Zigoto/citologia , Zigoto/crescimento & desenvolvimentoRESUMO
Adenosine 3',5'-cyclic monophosphate (cAMP) is a universal signaling molecule that acts as a second messenger in various organisms. It is well established that cAMP plays essential roles across the tree of life, although the function of cAMP in land plants has long been debated. We previously identified the enzyme with both adenylyl cyclase (AC) and cAMP phosphodiesterase (PDE) activity as the cAMP-synthesis/hydrolysis enzyme COMBINED AC with PDE (CAPE) in the liverwort Marchantia polymorpha. CAPE is conserved in streptophytes that reproduce with motile sperm; however, the precise function of CAPE is not yet known. In this study, we demonstrate that the loss of function of CAPE in M. polymorpha led to male infertility due to impaired sperm flagellar motility. We also found that two genes encoding the regulatory subunits of cAMP-dependent protein kinase (PKA-R) were also involved in sperm motility. Based on these findings, it is evident that CAPE and PKA-Rs act as a cAMP signaling module that regulates sperm motility in M. polymorpha. Therefore, our results have shed light on the function of cAMP signaling and sperm motility regulators in land plants. This study suggests that cAMP signaling plays a common role in plant and animal sperm motility.
Assuntos
Marchantia , Masculino , Animais , Marchantia/genética , AMP Cíclico/metabolismo , Motilidade dos Espermatozoides/genética , Sementes/metabolismo , Adenilil Ciclases/metabolismo , Espermatozoides/metabolismoRESUMO
BACKGROUND: Genetic abnormalities like Y chromosome microdeletions are implicated in male infertility. This study investigated the association of azoospermia factor (AZF) region microdeletions with unsuccessful assisted reproductive techniques (ART), including in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). METHODS: This cross-sectional analysis study examined 80 Iranian oligospermic men (mean age 34 years) with prior failed ICSI and IVF cycles (IR.IAU.TNB.REC.1401.041). Semen analysis evaluated quantity/quality parameters based on World Health Organization guidelines. Participants were stratified by sperm DNA fragmentation (SDF) levels into: control (SDF < 15%, n = 20), mild elevation (15% ≤ SDF ≤ 30%, n = 60), and high (SDF > 30%, n = 20). Multiplex PCR mapped AZF microdeletions in the high SDF group. The AZF-associated genes were selected by RNA Seq analysis, and the candidate genes were checked for expression level by real-time PCR. RESULTS: High SDF individuals exhibited poorer semen metrics, including 69% lower sperm concentration (P = 0.04) than those without SDF. Of this subset, 45% (9/20 men) harboured predominately AZF microdeletions. Men with AZF microdeletions showed higher SDF (32% vs 21%, P = 0.02) and altered AZF-associated genes expression. As USP9Y 3-fold, UTY 1.3-fold, and BPY2 1-fold revealed up-regulation, while IQCF1 8-fold, CDY 6.5-fold, DAZ 6-fold, and DDX3Y 1-fold underwent down-regulation. The PAWP gene was also down-regulated (5.7-fold, P = 0.029) in the IVF/ICSI failure group. CONCLUSION: AZF microdeletions significantly impact male infertility and ART outcomes. High SDF individuals exhibited poorer semen metrics, with 45% AZF microdeletions. These microdeletions altered AZF-associated genes expression, affecting fertility mediator PAWP independently. Dual AZF and SDF screening enables personalized management in severe male infertility, potentially explaining IVF/ICSI failures.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Y , Infertilidade Masculina , Aberrações dos Cromossomos Sexuais , Transtornos do Cromossomo Sexual no Desenvolvimento Sexual , Humanos , Masculino , Cromossomos Humanos Y/genética , Infertilidade Masculina/genética , Adulto , Transtornos do Cromossomo Sexual no Desenvolvimento Sexual/genética , Estudos Transversais , Análise do Sêmen , Injeções de Esperma Intracitoplásmicas , Fertilização in vitro , Técnicas de Reprodução Assistida , Fragmentação do DNA , Espermatozoides/metabolismo , Espermatozoides/patologia , Irã (Geográfico) , Fertilidade/genética , Regulação da Expressão Gênica/genética , Contagem de EspermatozoidesRESUMO
Primate-specific genes (PSGs) tend to be expressed in the brain and testis. This phenomenon is consistent with brain evolution in primates but is seemingly contradictory to the similarity of spermatogenesis among mammals. Here, using whole-exome sequencing, we identified deleterious variants of X-linked SSX1 in six unrelated men with asthenoteratozoospermia. SSX1 is a PSG expressed predominantly in the testis, and the SSX family evolutionarily expanded independently in rodents and primates. As the mouse model could not be used for studying SSX1, we used a non-human primate model and tree shrews, which are phylogenetically similar to primates, to knock down (KD) Ssx1 expression in the testes. Consistent with the phenotype observed in humans, both Ssx1-KD models exhibited a reduced sperm motility and abnormal sperm morphology. Further, RNA sequencing indicated that Ssx1 deficiency influenced multiple biological processes during spermatogenesis. Collectively, our experimental observations in humans and cynomolgus monkey and tree shrew models highlight the crucial role of SSX1 in spermatogenesis. Notably, three of the five couples who underwent intra-cytoplasmic sperm injection treatment achieved a successful pregnancy. This study provides important guidance for genetic counseling and clinical diagnosis and, significantly, describes the approaches for elucidating the functions of testis-enriched PSGs in spermatogenesis.
Assuntos
Astenozoospermia , Tupaia , Animais , Masculino , Macaca fascicularis , Primatas , Sêmen , Motilidade dos Espermatozoides , TupaiidaeRESUMO
Equal cell division relies upon astral microtubule-based centering mechanisms, yet how the interplay between mitotic entry, cortical force generation and long astral microtubules leads to symmetric cell division is not resolved. We report that a cortically located sperm aster displaying long astral microtubules that penetrate the whole zygote does not undergo centration until mitotic entry. At mitotic entry, we find that microtubule-based cortical pulling is lost. Quantitative measurements of cortical pulling and cytoplasmic pulling together with physical simulations suggested that a wavelike loss of cortical pulling at mitotic entry leads to aster centration based on cytoplasmic pulling. Cortical actin is lost from the cortex at mitotic entry coincident with a fall in cortical tension from â¼300pN/µm to â¼100pN/µm. Following the loss of cortical force generators at mitotic entry, long microtubule-based cytoplasmic pulling is sufficient to displace the aster towards the cell center. These data reveal how mitotic aster centration is coordinated with mitotic entry in chordate zygotes.
Assuntos
Sêmen , Fuso Acromático , Masculino , Humanos , Microtúbulos , Citoplasma , Divisão CelularRESUMO
Proper connection between the sperm head and tail is critical for sperm motility and fertilization. Head-tail linkage is mediated by the Head-Tail Coupling Apparatus (HTCA), which secures the axoneme (tail) to the nucleus (head). However, the molecular architecture of the HTCA is poorly understood. Here, we use Drosophila to investigate formation and remodeling of the HTCA throughout spermiogenesis by visualizing key components of this complex. Using structured illumination microscopy, we demonstrate that key HTCA proteins Spag4 and Yuri form a 'Centriole Cap' that surrounds the centriole (or Basal Body) as it invaginates into the surface of the nucleus. As development progresses, the centriole is laterally displaced to the side of the nucleus while the HTCA expands under the nucleus, forming what we term the 'Nuclear Shelf.' We next show that the proximal centriole-like (PCL) structure is positioned under the Nuclear Shelf, functioning as a critical stabilizer of centriole-nuclear attachment. Together, our data indicate that the HTCA is a complex, multi-point attachment site that simultaneously engages the PCL, the centriole, and the nucleus to ensure proper head-tail connection during late-stage spermiogenesis.