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Genes & Genetic Systems Jun 2022Meiosis is a crucial process for spermatogenesis and oogenesis. Initiation of meiosis coincides with spermatocyte differentiation and is followed by meiotic prophase, a... (Review)
Review
Meiosis is a crucial process for spermatogenesis and oogenesis. Initiation of meiosis coincides with spermatocyte differentiation and is followed by meiotic prophase, a prolonged G2 phase that ensures the completion of numerous meiosis-specific chromosome events. During meiotic prophase, chromosomes are organized into axis-loop structures, which underlie meiosis-specific events such as meiotic recombination and homolog synapsis. In spermatocytes, meiotic prophase is accompanied by robust alterations of gene expression programs and chromatin status for subsequent sperm production. The mechanisms regulating meiotic initiation and subsequent meiotic prophase programs are enigmatic. Recently, we discovered MEIOSIN (Meiosis initiator), a DNA-binding protein that directs the switch from mitosis to meiosis. This review mainly focuses on how MEIOSIN is involved in meiotic initiation and the meiotic prophase program during spermatogenesis. Further, we discuss the downstream genes activated by MEIOSIN, which are crucial for meiotic prophase-specific events, from the viewpoint of chromosome dynamics and the gene expression program.
Topics: Chromosome Pairing; Humans; Male; Meiosis; Mitosis; Spermatocytes; Spermatogenesis
PubMed: 34955498
DOI: 10.1266/ggs.21-00054 -
Cell Discovery Aug 2023During meiosis, at least one crossover must occur per homologous chromosome pair to ensure normal progression of meiotic division and accurate chromosome segregation....
During meiosis, at least one crossover must occur per homologous chromosome pair to ensure normal progression of meiotic division and accurate chromosome segregation. However, the mechanism of crossover formation is not fully understood. Here, we report a novel recombination protein, C12ORF40/REDIC1, essential for meiotic crossover formation in mammals. A homozygous frameshift mutation in C12orf40 (c.232_233insTT, p.Met78Ilefs*2) was identified in two infertile men with meiotic arrest. Spread mouse spermatocyte fluorescence immunostaining showed that REDIC1 forms discrete foci between the paired regions of homologous chromosomes depending on strand invasion and colocalizes with MSH4 and later with MLH1 at the crossover sites. Redic1 knock-in (KI) mice homozygous for mutation c.232_233insTT are infertile in both sexes due to insufficient crossovers and consequent meiotic arrest, which is also observed in our patients. The foci of MSH4 and TEX11, markers of recombination intermediates, are significantly reduced numerically in the spermatocytes of Redic1 KI mice. More importantly, our biochemical results show that the N-terminus of REDIC1 binds branched DNAs present in recombination intermediates, while the identified mutation impairs this interaction. Thus, our findings reveal a crucial role for C12ORF40/REDIC1 in meiotic crossover formation by stabilizing the recombination intermediates, providing prospective molecular targets for the clinical diagnosis and therapy of infertility.
PubMed: 37612290
DOI: 10.1038/s41421-023-00577-5 -
Proceedings of the National Academy of... Feb 2021Meiosis is a specialized cell division that creates haploid germ cells from diploid progenitors. Through differential RNA expression analyses, we previously identified a...
Meiosis is a specialized cell division that creates haploid germ cells from diploid progenitors. Through differential RNA expression analyses, we previously identified a number of mouse genes that were dramatically elevated in spermatocytes, relative to their very low expression in spermatogonia and somatic organs. Here, we investigated in detail one of these genes, and independently conclude that it encodes a male germline-specific protein, in agreement with a recent report. We demonstrated that it is essential for pachynema progression in spermatocytes and named it male pachynema-specific (MAPS) protein. Mice lacking ( ) suffered from pachytene arrest and spermatocyte death, leading to male infertility, whereas female fertility was not affected. Interestingly, pubertal spermatocytes were arrested at early pachytene stage, accompanied by defects in DNA double-strand break (DSB) repair, crossover formation, and XY body formation. In contrast, adult spermatocytes only exhibited partially defective crossover but nonetheless were delayed or failed in progression from early to mid- and late pachytene stage, resulting in cell death. Furthermore, we report a significant transcriptional dysregulation in autosomes and XY chromosomes in both pubertal and adult pachytene spermatocytes, including failed meiotic sex chromosome inactivation (MSCI). Further experiments revealed that MAPS overexpression in vitro dramatically decreased the ubiquitination levels of cellular proteins. Conversely, in pachytene cells, protein ubiquitination was dramatically increased, likely contributing to the large-scale disruption in gene expression in pachytene cells. Thus, MAPS is a protein essential for pachynema progression in male mice, possibly in mammals in general.
Topics: Animals; Chromosome Pairing; DNA Repair; Female; Infertility, Male; Male; Meiosis; Mice; Mice, Inbred C57BL; Mice, Knockout; Nuclear Proteins; Pachytene Stage; Sex Chromosomes; Spermatocytes; Spermatogenesis
PubMed: 33602822
DOI: 10.1073/pnas.2025421118 -
Gene Jul 2019The functional sperm is the key factor for species continuation. The process spermatogenesis, to produce mature sperm is quite complex. It begins with the proliferation... (Review)
Review
The functional sperm is the key factor for species continuation. The process spermatogenesis, to produce mature sperm is quite complex. It begins with the proliferation and differentiation of spermatogonia, which develop from primary spermatocytes to secondary spermatocytes and round spermatids, which eventually develop into fertile mature sperm. Spermiogenesis is the latest stage of spermatogenesis, where the round spermatids undergo a series of dramatic morphological changes and extreme condensation of chromatin to construct mature sperm with species-specific shape. During spermiogenesis, chromatin remodeling is a unique progress. It leads the nucleosome from a histone-based structure to a mostly protamine-based configuration. The main events of chromatin remodeling are the replacement of histone by histone variants, hyperacetylation, transient DNA strand breaks and repair, variants by transition proteins and finally by protamines. In this review, we synthesize and summarize the current knowledge on the progress of chromatin remodeling during spermiogenesis. We straighten out the chronological order of chromatin remodeling and illustrate the possible regulation mechanisms of each step.
Topics: Animals; Chromatin; Chromatin Assembly and Disassembly; DNA; Histones; Humans; Male; Sperm Maturation; Spermatids; Spermatocytes; Spermatogenesis; Spermatozoa
PubMed: 31085275
DOI: 10.1016/j.gene.2019.05.027 -
Cell Proliferation Jan 2022Accumulating evidences show that the regulatory network of m A modification is essential for mammalian spermatogenesis. However, as an m A reader, the roles of...
OBJECTIVES
Accumulating evidences show that the regulatory network of m A modification is essential for mammalian spermatogenesis. However, as an m A reader, the roles of YTHDF2 remain enigmatic due to the lack of a proper model. Here, we employed the germ cell conditional knockout mouse model and explored the function of YTHDF2 in spermatogenesis.
MATERIALS AND METHODS
Ythdf2 germ cell conditional knockout mice were obtained by crossing Ythdf2-floxed mice with Vasa-Cre and Stra8-Cre mice. Haematoxylin and eosin (HE) staining, immunofluorescent staining and Western blotting were used for phenotyping. CASA, IVF and ICSI were applied for sperm function analysis. RNA-seq, YTHDF2-RIP-seq and quantitative real-time PCR were used to explore transcriptome changes and molecular mechanism analysis.
RESULTS
Our results showed that YTHDF2 was highly expressed in spermatogenic cells. The germ cell conditional knockout males were sterile, and their sperm displayed malformation, impaired motility, and lost fertilization ability. During differentiated spermatogonia transiting to pachytene spermatocyte, most m A-modified YTHDF2 targets that were degraded in control germ cells persisted in pachytene spermatocytes of Ythdf2-vKO mice. These delayed mRNAs were mainly enriched in pathways related to the regulation of transcription, and disturbed the transcriptome of round spermatid and elongated spermatid subsequently.
CONCLUSION
Our data demonstrate that YTHDF2 facilitates the timely turnover of phase-specific transcripts to ensure the proper progression of spermatogenesis, which highlights a critical role of YTHDF2 in spermatogenesis.
Topics: Adenosine; Animals; Fertility; Fertilization; Gene Deletion; Germ Cells; Male; Mice, Inbred C57BL; Mice, Knockout; RNA, Messenger; RNA-Binding Proteins; Spermatogenesis; Spermatozoa; Transcriptome; Mice
PubMed: 34850470
DOI: 10.1111/cpr.13164 -
Genes Jul 2019Telomeres are repeat regions of DNA that cap either end of each chromosome, thereby providing stability and protection from the degradation of gene-rich regions. Each...
Telomeres are repeat regions of DNA that cap either end of each chromosome, thereby providing stability and protection from the degradation of gene-rich regions. Each cell replication causes the loss of telomeric repeats due to incomplete DNA replication, though it is well-established that progressive telomere shortening is evaded in male germ cells by the maintenance of active telomerase. However, germ cell telomeres are still susceptible to disruption or insult by oxidative stress, toxicant exposure, and aging. Our aim was to examine the relative telomere length (rTL) in an outbred Sprague Dawley (SD) and an inbred Brown Norway (BN) rat model for paternal aging. No significant differences were found when comparing pachytene spermatocytes (PS), round spermatids (RS), and sperm obtained from the caput and cauda of the epididymis of young and aged SD rats; this is likely due to the high variance observed among individuals. A significant age-dependent decrease in rTL was observed from 115.6 (±6.5) to 93.3 (±6.3) in caput sperm and from 142.4 (±14.6) to 105.3 (±2.5) in cauda sperm from BN rats. Additionally, an increase in rTL during epididymal maturation was observed in both strains, most strikingly from 115.6 (±6.5) to 142 (±14.6) in young BN rats. These results confirm the decrease in rTL in rodents, but only when an inbred strain is used, and represent the first demonstration that rTL changes as sperm transit through the epididymis.
Topics: Aging; Animals; Male; Rats; Rats, Inbred BN; Rats, Sprague-Dawley; Spermatids; Spermatocytes; Spermatogenesis; Telomere; Telomere Shortening
PubMed: 31336906
DOI: 10.3390/genes10070525 -
Cell Death & Disease Dec 2023Glutathione synthetase (GSS) catalyzes the final step in the synthesis of glutathione (GSH), a well-established antioxidant. Research on the specific roles of the Gss...
Glutathione synthetase (GSS) catalyzes the final step in the synthesis of glutathione (GSH), a well-established antioxidant. Research on the specific roles of the Gss gene during spermatogenesis remains limited due to the intricate structure of testis. In this study, we identified pachytene spermatocytes as the primary site of GSS expression and generated a mouse model with postnatal deletion of Gss using Stra8-Cre (S8) to investigate the role of GSS in germ cells. The impact of Gss knockout on reducing male fertility is age-dependent and caused by ferroptosis in the testis. The 2-month-old S8/Gss male mice exhibited normal fertility, due to a compensatory increase in GPX4, which prevented the accumulation of ROS. With aging, there was a decline in GPX4 and an increase in ALOX15 levels observed in 8-month-old S8/Gss mice, resulting in the accumulation of ROS, lipid peroxidation, and ultimately testicular ferroptosis. We found that testicular ferroptosis did not affect spermatogonia, but caused meiosis disruption and acrosome heterotopia. Then the resulting aberrant sperm showed lower concentration and abnormal morphology, leading to reduced fertility. Furthermore, these injuries could be functionally rescued by inhibiting ferroptosis through intraperitoneal injection of GSH or Fer-1. In summary, Gss in germ cells play a crucial role in the resistance to oxidative stress injury in aged mice. Our findings deepen the understanding of ferroptosis during spermatogenesis and suggest that inhibiting ferroptosis may be a potential strategy for the treatment of male infertility.
Topics: Glutathione Synthase; Spermatocytes; Infertility, Male; Testis; Reactive Oxygen Species; Ferroptosis; Gene Knockout Techniques; Germ Cells; Meiosis; Spermatogenesis; Acrosome; Autophagy; Male; Female; Animals; Mice; Age Factors
PubMed: 38114454
DOI: 10.1038/s41419-023-06359-x -
Genes Nov 2021Regulation of transcriptional activity during meiosis depends on the interrelated processes of recombination and synapsis. In eutherian mammal spermatocytes,...
Regulation of transcriptional activity during meiosis depends on the interrelated processes of recombination and synapsis. In eutherian mammal spermatocytes, transcription levels change during prophase-I, being low at the onset of meiosis but highly increased from pachytene up to the end of diplotene. However, X and Y chromosomes, which usually present unsynapsed regions throughout prophase-I in male meiosis, undergo a specific pattern of transcriptional inactivation. The interdependence of synapsis and transcription has mainly been studied in mammals, basically in mouse, but our knowledge in other unrelated phylogenetically species is more limited. To gain new insights on this issue, here we analyzed the relationship between synapsis and transcription in spermatocytes of the grasshopper . Autosomal chromosomes of this species achieve complete synapsis; however, the single X sex chromosome remains always unsynapsed and behaves as a univalent. We studied transcription in meiosis by immunolabeling with RNA polymerase II phosphorylated at serine 2 and found that whereas autosomes are active from leptotene up to diakinesis, the X chromosome is inactive throughout meiosis. This inactivation is accompanied by the accumulation of, at least, two repressive epigenetic modifications: H3 methylated at lysine 9 and H2AX phosphorylated at serine 139. Furthermore, we identified that X chromosome inactivation occurs in premeiotic spermatogonia. Overall, our results indicate: (i) transcription regulation in spermatogenesis differs from the canonical pattern found in mammals and (ii) X chromosome inactivation is likely preceded by a process of heterochromatinization before the initiation of meiosis.
Topics: Animals; Chromosome Pairing; Epigenesis, Genetic; Female; Gene Silencing; Grasshoppers; Histones; Lysine; Male; Meiosis; Meiotic Prophase I; RNA Polymerase II; Spermatocytes; Spermatogenesis; X Chromosome; X Chromosome Inactivation; Y Chromosome
PubMed: 34946793
DOI: 10.3390/genes12121844 -
PLoS Genetics Sep 2022Control over gene expression is exerted, in multiple stages of spermatogenesis, at the post-transcriptional level by RNA binding proteins (RBPs). We identify here an...
Control over gene expression is exerted, in multiple stages of spermatogenesis, at the post-transcriptional level by RNA binding proteins (RBPs). We identify here an essential role in mammalian spermatogenesis and male fertility for 'RNA binding protein 46' (RBM46). A highly evolutionarily conserved gene, Rbm46 is also essential for fertility in both flies and fish. We found Rbm46 expression was restricted to the mouse germline, detectable in males in the cytoplasm of premeiotic spermatogonia and meiotic spermatocytes. To define its requirement for spermatogenesis, we generated Rbm46 knockout (KO, Rbm46-/-) mice; although male Rbm46-/- mice were viable and appeared grossly normal, they were infertile. Testes from adult Rbm46-/- mice were small, with seminiferous tubules containing only Sertoli cells and few undifferentiated spermatogonia. Using genome-wide unbiased high throughput assays RNA-seq and 'enhanced crosslinking immunoprecipitation' coupled with RNA-seq (eCLIP-seq), we discovered RBM46 could bind, via a U-rich conserved consensus sequence, to a cohort of mRNAs encoding proteins required for completion of differentiation and subsequent meiotic initiation. In summary, our studies support an essential role for RBM46 in regulating target mRNAs during spermatogonia differentiation prior to the commitment to meiosis in mice.
Topics: Animals; Cell Differentiation; Male; Mammals; Meiosis; Mice; Mice, Knockout; RNA, Messenger; RNA-Binding Proteins; Spermatocytes; Spermatogenesis; Spermatogonia; Testis
PubMed: 36129965
DOI: 10.1371/journal.pgen.1010416 -
Cells Apr 2023Studies on the gene regulation of spermatogenesis are of unusual significance for maintaining male reproduction and treating male infertility. Here, we have...
Studies on the gene regulation of spermatogenesis are of unusual significance for maintaining male reproduction and treating male infertility. Here, we have demonstrated, for the first time, that a loss of ZBTB40 function leads to abnormalities in the morphological and phenotypic characteristics of mouse spermatocytes and spermatids as well as male infertility. We revealed that Zbtb40 was expressed in spermatocytes of mouse testes, and it was co-localized with γH2AX in mouse secondary spermatocytes. Interestingly, spermatocytes of knockout mice had longer telomeres, compromised double-strand break (DSB) repair in the sex chromosome, and a higher apoptosis ratio compared to wild-type (WT) mice. The testis weight, testicular volume, and cauda epididymis body weight of the male mice were significantly lower than in WT mice. Mating tests indicated that male mice were able to mate normally, but they failed to produce any pups. Notably, sperm of mice showed flagellum deformities and abnormal acrosome biogenesis. Furthermore, a ZBTB40 mutation was associated with non-obstructive azoospermia. Our results implicate that ZBTB40 deficiency leads to morphological and phenotypic abnormalities of spermatocytes and spermatids and causes male infertility. This study thus offers a new genetic mechanism regulating mammalian spermatogenesis and provides a novel target for gene therapy in male infertility.
Topics: Animals; Humans; Male; Mice; Infertility, Male; Mice, Knockout; Semen; Spermatocytes; Spermatozoa; Testis; DNA-Binding Proteins
PubMed: 37174664
DOI: 10.3390/cells12091264