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Development (Cambridge, England) Jul 2023Retinoic acid (RA) is the proposed mammalian 'meiosis inducing substance'. However, evidence for this role comes from studies in the fetal ovary, where germ cell...
Retinoic acid (RA) is the proposed mammalian 'meiosis inducing substance'. However, evidence for this role comes from studies in the fetal ovary, where germ cell differentiation and meiotic initiation are temporally inseparable. In the postnatal testis, these events are separated by more than 1 week. Exploiting this difference, we discovered that, although RA is required for spermatogonial differentiation, it is dispensable for the subsequent initiation, progression and completion of meiosis. Indeed, in the absence of RA, the meiotic transcriptome program in both differentiating spermatogonia and spermatocytes entering meiosis was largely unaffected. Instead, transcripts encoding factors required during spermiogenesis were aberrant during preleptonema, and the subsequent spermatid morphogenesis program was disrupted such that no sperm were produced. Taken together, these data reveal a RA-independent model for male meiotic initiation.
Topics: Animals; Female; Male; Testis; Tretinoin; Spermatogenesis; Spermatogonia; Spermatozoa; Meiosis; Mammals
PubMed: 37350382
DOI: 10.1242/dev.201638 -
Nature Reviews. Genetics May 2024Sexually reproducing eukaryotes use recombination between homologous chromosomes to promote chromosome segregation during meiosis. Meiotic recombination is almost... (Review)
Review
Sexually reproducing eukaryotes use recombination between homologous chromosomes to promote chromosome segregation during meiosis. Meiotic recombination is almost universally conserved in its broad strokes, but specific molecular details often differ considerably between taxa, and the proteins that constitute the recombination machinery show substantial sequence variability. The extent of this variation is becoming increasingly clear because of recent increases in genomic resources and advances in protein structure prediction. We discuss the tension between functional conservation and rapid evolutionary change with a focus on the proteins that are required for the formation and repair of meiotic DNA double-strand breaks. We highlight phylogenetic relationships on different time scales and propose that this remarkable evolutionary plasticity is a fundamental property of meiotic recombination that shapes our understanding of molecular mechanisms in reproductive biology.
Topics: DNA Repair; Phylogeny; Homologous Recombination; Meiosis; DNA Breaks, Double-Stranded
PubMed: 38036793
DOI: 10.1038/s41576-023-00669-8 -
Nature Structural & Molecular Biology Sep 2023SUMOylation regulates numerous cellular processes, but what represents the essential functions of this protein modification remains unclear. To address this, we...
SUMOylation regulates numerous cellular processes, but what represents the essential functions of this protein modification remains unclear. To address this, we performed genome-scale CRISPR-Cas9-based screens, revealing that the BLM-TOP3A-RMI1-RMI2 (BTRR)-PICH pathway, which resolves ultrafine anaphase DNA bridges (UFBs) arising from catenated DNA structures, and the poorly characterized protein NIP45/NFATC2IP become indispensable for cell proliferation when SUMOylation is inhibited. We demonstrate that NIP45 and SUMOylation orchestrate an interphase pathway for converting DNA catenanes into double-strand breaks (DSBs) that activate the G2 DNA-damage checkpoint, thereby preventing cytokinesis failure and binucleation when BTRR-PICH-dependent UFB resolution is defective. NIP45 mediates this new TOP2-independent DNA catenane resolution process via its SUMO-like domains, promoting SUMOylation of specific factors including the SLX4 multi-nuclease complex, which contributes to catenane conversion into DSBs. Our findings establish that SUMOylation exerts its essential role in cell proliferation by enabling resolution of toxic DNA catenanes via nonepistatic NIP45- and BTRR-PICH-dependent pathways to prevent mitotic failure.
Topics: DNA, Catenated; Anaphase; DNA; Sumoylation
PubMed: 37474739
DOI: 10.1038/s41594-023-01045-0 -
Cell Reports Oct 2023Perturbing the transcriptome of mammalian oocytes results in meiotic failure. We previously reported that RNA-exosome-associated RNase, EXOSC10, degrades unwanted...
Perturbing the transcriptome of mammalian oocytes results in meiotic failure. We previously reported that RNA-exosome-associated RNase, EXOSC10, degrades unwanted protein-coding RNA and processes ribosomal RNA to ensure proper oocyte maturation. Here, we establish oocyte-specific knockout mice of another RNA-exosome-associated RNase, DIS3. Mutant females (Dis3) exhibit significantly reduced fertility because oocytes arrest after the growth phase. Single-oocyte RNA sequencing (RNA-seq) and CUT&Tag analyses show that DIS3 degrades intergenic RNA and mediates transcription silencing that is essential for chromatin condensation and resumption of meiosis. Dis3 oocytes exhibit elevated H3K27me3 in a pre-defined manner due to insufficient demethylation. During oocyte growth, EXOSC10 functions with DIS3 to degrade intergenic RNA. Double-knockout oocytes have earlier growth defects and more accumulated transcripts. We conclude that RNA exosomes synergistically degrade unwanted RNA and mediate transcription termination to ensure transcriptome integrity during oocyte development.
Topics: Mice; Animals; Female; RNA Polymerase II; Exosomes; Oocytes; Meiosis; RNA; Endoribonucleases; Fertility; Mammals
PubMed: 37831603
DOI: 10.1016/j.celrep.2023.113247 -
Current Biology : CB Jul 2023Centrosomes are multi-protein organelles that function as microtubule (MT) organizing centers (MTOCs), ensuring spindle formation and chromosome segregation during cell...
Centrosomes are multi-protein organelles that function as microtubule (MT) organizing centers (MTOCs), ensuring spindle formation and chromosome segregation during cell division. Centrosome structure includes core centrioles that recruit pericentriolar material (PCM) that anchors γ-tubulin to nucleate MTs. In Drosophila melanogaster, PCM organization depends on proper regulation of proteins like Spd-2, which dynamically localizes to centrosomes and is required for PCM, γ-tubulin, and MTOC activity in brain neuroblast (NB) mitosis and male spermatocyte (SC) meiosis. Some cells have distinct requirements for MTOC activity due to differences in characteristics like cell size or whether they are mitotic or meiotic. How centrosome proteins achieve cell-type-specific functional differences is poorly understood. Previous work identified alternative splicing and binding partners as contributors to cell-type-specific differences in centrosome function. Gene duplication, which can generate paralogs with specialized functions, is also implicated in centrosome gene evolution, including cell-type-specific centrosome genes. To gain insight into cell-type-specific differences in centrosome protein function and regulation, we investigated a duplication of Spd-2 in Drosophila willistoni, which has Spd-2A (ancestral) and Spd-2B (derived). We find that Spd-2A functions in NB mitosis, whereas Spd-2B functions in SC meiosis. Ectopically expressed Spd-2B accumulates and functions in mitotic NBs, but ectopically expressed Spd-2A failed to accumulate in meiotic SCs, suggesting cell-type-specific differences in translation or protein stability. We mapped this failure to accumulate and function in meiosis to the C-terminal tail domain of Spd-2A, revealing a novel regulatory mechanism that can potentially achieve differences in PCM function across cell types.
Topics: Animals; Male; Centrioles; Centrosome; Drosophila; Gene Duplication; Meiosis; Mitosis; Tubulin; Cytoskeletal Proteins; Drosophila Proteins
PubMed: 37379844
DOI: 10.1016/j.cub.2023.06.020 -
Nature Communications Oct 2023Meiosis is differently regulated in males and females. In females, germ cells initiate meiosis within a limited time period in the fetal ovary and undergo a prolonged...
Meiosis is differently regulated in males and females. In females, germ cells initiate meiosis within a limited time period in the fetal ovary and undergo a prolonged meiotic arrest until puberty. However, how meiosis initiation is coordinated with the cell cycle to coincide with S phase remains elusive. Here, we demonstrate that STRA8 binds to RB via the LXCXE motif. Mutation of the RB-binding site of STRA8 in female mice delays meiotic entry, which consequently delays progression of meiotic prophase and leads to precocious depletion of the oocyte pool. Single-cell RNA-sequencing analysis reveals that the STRA8-RB interaction is required for S phase entry and meiotic gene activation, ensuring precise timing of meiosis initiation in oocytes. Strikingly, the results suggest STRA8 could sequester RB from E2F during pre-meiotic G1/S transition. This study highlights the gene regulatory mechanisms underlying the female-specific mode of meiotic initiation in mice.
Topics: Animals; Female; Male; Mice; Adaptor Proteins, Signal Transducing; Gene Expression Regulation; Germ Cells; Meiosis; Sexual Maturation; Retinoblastoma Protein
PubMed: 37880249
DOI: 10.1038/s41467-023-42259-6 -
Molecular Biology of the Cell Sep 2023During exit from meiosis II, cells undergo several structural rearrangements, including disassembly of the meiosis II spindles and cytokinesis. Each of these changes is...
During exit from meiosis II, cells undergo several structural rearrangements, including disassembly of the meiosis II spindles and cytokinesis. Each of these changes is regulated to ensure that they occur at the proper time. Previous studies have demonstrated that both which encodes a STE20-family GCKIII kinase, and , which encodes a meiosis-specific activator of the Anaphase Promoting Complex, are required for both meiosis II spindle disassembly and cytokinesis in the budding yeast . We examine the relationship between meiosis II spindle disassembly and cytokinesis and find that the meiosis II spindle disassembly failure in and cells is not the cause of the cytokinesis defect. We also see that the spindle disassembly defects in and cells are phenotypically distinct. We examined known microtubule-associated proteins Ase1, Cin8, and Bim1, and found that is required for the proper loss of Ase1 and Cin8 on meiosis II spindles while is required for Bim1 loss in meiosis II. Taken together, these data indicate that and promote distinct aspects of meiosis II spindle disassembly, and that both pathways are required for the successful completion of meiosis.
Topics: Cell Cycle Proteins; Saccharomyces cerevisiae Proteins; Meiosis; Saccharomyces cerevisiae; Anaphase-Promoting Complex-Cyclosome; Spindle Apparatus; Microtubule-Associated Proteins
PubMed: 37436806
DOI: 10.1091/mbc.E23-03-0096 -
Molecular Cell Aug 2023Crossovers (COs), the exchange of homolog arms, are required for accurate chromosome segregation during meiosis. Studies in yeast have described the single-end invasion...
Crossovers (COs), the exchange of homolog arms, are required for accurate chromosome segregation during meiosis. Studies in yeast have described the single-end invasion (SEI) intermediate: a stabilized 3' end annealed with the homolog as the first detectible CO precursor. SEIs are thought to differentiate into double Holliday junctions (dHJs) that are resolved by MutLgamma (MLH1/MLH3) into COs. Currently, we lack knowledge of early steps of mammalian CO recombination or how intermediates are differentiated in any organism. Using comprehensive analysis of recombination in thirteen different genetic conditions with varying levels of compromised CO resolution, we infer CO precursors include asymmetric SEI-like intermediates and dHJs in mouse. In contrast to yeast, MLH3 is structurally required to differentiate CO precursors into dHJs. We verify conservation of aspects of meiotic recombination and show unique features in mouse, providing mechanistic insight into CO formation.
Topics: Animals; Mice; Saccharomyces cerevisiae; Meiosis; Chromosome Segregation; DNA, Cruciform; Mammals
PubMed: 37595556
DOI: 10.1016/j.molcel.2023.07.022 -
Biology of Reproduction Apr 2024Histone post-translational modifications, such as phosphorylation, methylation, acetylation, and ubiquitination, play vital roles in various chromatin-based cellular... (Review)
Review
Histone post-translational modifications, such as phosphorylation, methylation, acetylation, and ubiquitination, play vital roles in various chromatin-based cellular processes. Meiosis is crucial for organisms that depend on sexual reproduction to produce haploid gametes, during which chromatin undergoes intricate conformational changes. An increasing body of evidence is clarifying the essential roles of histone post-translational modifications during meiotic divisions. In this review, we concentrate on the post-translational modifications of H2A, H2B, H3, and H4, as well as the linker histone H1, that are required for meiosis, and summarize recent progress in understanding how these modifications influence diverse meiotic events. Finally, challenges and exciting open questions for future research in this field are discussed. Summary Sentence Diverse histone post-translational modifications exert important effects on the meiotic cell cycle and these "histone codes" in meiosis might lead to the development of novel therapeutic strategies against reproductive diseases.
Topics: Histones; Chromatin; Protein Processing, Post-Translational; Phosphorylation; Meiosis; Acetylation
PubMed: 38224305
DOI: 10.1093/biolre/ioae011 -
Journal of Advanced Research Sep 2023The R-loop is a naturally formed three-strand nucleic acid structure that recently has been reported to participate in multiple biological processes and helped answer...
INTRODUCTION
The R-loop is a naturally formed three-strand nucleic acid structure that recently has been reported to participate in multiple biological processes and helped answer some previously unexplained scientific questions. Meiosis process involves multiple chromatin-related events such as DNA double-stranded breaks (DSB) formation, repairing and transcriptional dynamics.
OBJECTIVES
Explore the regulatory roles and physiological functions of R-loops in the mammalian meiosis process.
METHODS
In our study, using genome-wide S9.6 CUT & Tag seq, we first mapped the genomic distribution and dynamic changes of R-loop during the meiotic process in mice, from spermatogonia to secondary spermatocytes. And we further explore the role of R-loop in physiological conditions by constructing conditional knockout mice of Rnaseh1, which deleted the R-loop endonuclease before meiosis entry.
RESULTS
R-loop predominantly distributes at promoter-related regions and varies across different meiotic stages. By joint analysis with the corresponding transcriptome, we found that the R-loop was closely related to transcription during the meiotic process. The high frequency of promoter-related R-loop in meiotic cells is usually accompanied by high transcription activity, and we further verified this in the leptotene/zygotene to the pachytene transition process. Moreover, the lack of RNase H1 caused sterility in male mice with R-loop accumulation and abnormal DSB repair in spermatocytes. Further analysis showed that abnormal R-loop accumulation in the leptotene/zygotene stages influenced transcriptional regulation in the pachytene stage.
CONCLUSION
The mutual regulation of the R-loop and transcription plays an essential role in spermatogenesis. And R-loop is also important for the normal repair process of DSB during meiosis.
Topics: Male; Mice; Animals; R-Loop Structures; DNA Breaks, Double-Stranded; Meiosis; Spermatogenesis; Spermatocytes; Mice, Knockout; Mammals
PubMed: 36396044
DOI: 10.1016/j.jare.2022.10.016