bims-cebooc Biomed News
on Cell biology of oocytes
Issue of 2024–11–24
fourteen papers selected by
Gabriele Zaffagnini, Universität zu Köln
  1. Two mechanisms repress cyclin B1 translation to maintain prophase arrest in mouse oocytes.
  2. Spatiotemporal dynamics and selectivity of mRNA translation during mouse pre-implantation development.
  3. Chemically induced proximity reveals a Piezo-dependent meiotic checkpoint at the oocyte nuclear envelope.
  4. Single-cell multi-omics analysis of in vitro post-ovulatory aged oocytes revealed aging-dependent protein degradation.
  5. Znf706 regulates germ plasm assembly and primordial germ cell development in zebrafish.
  6. A tug-of-war between germ cell motility and intercellular bridges controls germline cyst formation in mice.
  7. DDX3 is critical for female fertility via translational control in oogenesis.
  8. Oocyte competence develops: nuclear maturation synchronously with cytoplasm maturation.
  9. ARPP19 phosphorylation site evolution and the switch in cAMP control of oocyte maturation in vertebrates.
  10. The completing of the second meiotic division by MII mouse oocytes correlates with the positioning of F-actin and mitochondria in the ooplasm.
  11. Analysis of single-cell RNA sequencing in human oocytes with diminished ovarian reserve uncovers mitochondrial dysregulation and translation deficiency.
  12. Population size interacts with reproductive longevity to shape the germline mutation rate.
  13. Non-canonical spatial organization of heterochromatin in mouse preimplantation embryos.
  14. Lysosomal catabolic activity promotes the exit of murine totipotent 2-cell state by silencing early-embryonic retrotransposons.
  1. Nat Commun. 2024 Nov 20. 15(1): 10044
    Two mechanisms repress cyclin B1 translation to maintain prophase arrest in mouse oocytes.
    Shiya Cheng, Melina Schuh.
      In mammals, oocytes are arrested in prophase of meiosis I for long periods of time. Prophase arrest is critical for reproduction because it allows oocytes to grow to their full size to support meiotic maturation and embryonic development. Prophase arrest requires the inhibitory phosphorylation of the mitotic kinase CDK1. Whether prophase arrest is also regulated at the translational level is unknown. Here, we show that prophase arrest is regulated by translational control of dormant cyclin B1 mRNAs. Using Trim-Away, we identify two mechanisms that maintain cyclin B1 dormancy and thus prophase arrest. First, a complex of the RNA-binding proteins DDX6, LSM14B and CPEB1 directly represses cyclin B1 translation through interacting with its 3'UTR. Second, cytoplasmic poly(A)-binding proteins (PABPCs) indirectly repress the translation of cyclin B1 and other poly(A)-tail-less or short-tailed mRNAs by sequestering the translation machinery on long-tailed mRNAs. Together, we demonstrate how RNA-binding proteins coordinately regulate prophase arrest, and reveal an unexpected role for PABPCs in controlling mRNA dormancy.
    DOI:  https://doi.org/10.1038/s41467-024-54161-w
  2. bioRxiv. 2024 Oct 28. pii: 2024.10.28.620693. [Epub ahead of print]
    Spatiotemporal dynamics and selectivity of mRNA translation during mouse pre-implantation development.
    Hao Ming, Rajan Iyyappan, Kianoush Kakavand, Michal Dvoran, Andrej Susor, Zongliang Jiang.
      Translational regulation is pivotal during preimplantation development. However, how mRNAs are selected for temporal regulation and their dynamic utilization and fate during this period are still unknown. Using a high-resolution ribosome profiling approach, we analyzed the transcriptome, as well as monosome- and polysome-bound RNAs of mouse oocytes and embryos, defining an unprecedented extent of spatiotemporal translational landscapes during this rapid developmental phase. We observed previously unknown mechanisms of translational selectivity, i.e., stage-wise deferral of loading monosome-bound mRNAs to polysome for active translation, continuous translation of both monosome and polysome-bound mRNAs at the same developmental stage, and priming to monosomes after initial activation. We showed that a eukaryotic initiation factor Eif1ad3, which is exclusively translated in the 2-Cell embryo, is required for ribosome biogenesis post embryonic genome activation. Our study thus provides genome-wide datasets and analyses of spatiotemporal translational dynamics accompanying mammalian germ cell and embryonic development and reveals the contribution of a novel translation initiation factor to mammalian pre-implantation development.
    DOI:  https://doi.org/10.1101/2024.10.28.620693
  3. Science. 2024 Nov 22. 386(6724): eadm7969
    Chemically induced proximity reveals a Piezo-dependent meiotic checkpoint at the oocyte nuclear envelope.
    Chenshu Liu, Abby F Dernburg.
      Sexual reproduction relies on robust quality control during meiosis. Assembly of the synaptonemal complex between homologous chromosomes (synapsis) regulates meiotic recombination and is crucial for accurate chromosome segregation in most eukaryotes. Synapsis defects can trigger cell cycle delays and, in some cases, apoptosis. We developed and deployed a chemically induced proximity system to identify key elements of this quality control pathway in Caenorhabditis elegans. Persistence of the polo-like kinase PLK-2 at pairing centers-specialized chromosome regions that interact with the nuclear envelope-induced apoptosis of oocytes in response to phosphorylation and destabilization of the nuclear lamina. Unexpectedly, the Piezo1/PEZO-1 channel localized to the nuclear envelope and was required to transduce this signal to promote apoptosis in maturing oocytes.
    DOI:  https://doi.org/10.1126/science.adm7969
  4. Mol Cell Proteomics. 2024 Nov 19. pii: S1535-9476(24)00172-5. [Epub ahead of print] 100882
    Single-cell multi-omics analysis of in vitro post-ovulatory aged oocytes revealed aging-dependent protein degradation.
    Yueshuai Guo, Mengmeng Gao, Xiaofei Liu, Haotian Zhang, Yue Wang, Tong Yan, Bing Wang, Xudong Han, Yaling Qi, Hui Zhu, Chenghao Situ, Yan Li, Xuejiang Guo.
      Once ovulated, the oocyte has to be fertilized in a short time window, or it will undergo post-ovulation aging (POA), whose underlying mechanisms are still not elucidated. Here, we optimized single-cell proteomics methods and performed single-cell transcriptomic, proteomic and phosphoproteomic analysis of fresh, POA, and melatonin-treated POA oocytes. POA oocytes showed down-regulation of most differentially expressed proteins, with little correlation with mRNA expression, and the protein changes can be rescued by melatonin treatment. MG132 treatment rescued the decreased fertilization and polyspermy rates, and up-regulated fragmentation and parthenogenesis rates of POA oocytes. MG132-treated oocytes displayed health status at proteome, phosphoproteome and fertilization ability similar to fresh oocytes, suggesting that protein stabilization might be the underlying mechanism for melatonin to rescue POA. The important roles of proteasome-mediated protein degradation during oocyte POA revealed by single-cell multi-omics analyses offer new perspectives for increasing oocyte quality during POA, and improving assisted reproduction technologies.
    Keywords:  Melatonin; Mouse; Multi-omics; Oocyte; Post-ovulation aging; Single cell
    DOI:  https://doi.org/10.1016/j.mcpro.2024.100882
  5. J Genet Genomics. 2024 Nov 19. pii: S1673-8527(24)00308-4. [Epub ahead of print]
    Znf706 regulates germ plasm assembly and primordial germ cell development in zebrafish.
    Weiying Zhang, Yaqi Li, Han Li, Xin Liu, Tao Zheng, Guangyuan Li, Boqi Liu, Tong Lv, Zihang Wei, Cencan Xing, Shunji Jia, Anming Meng, Xiaotong Wu.
      The cell fate of primordial germ cells (PGCs) in zebrafish is pre-determined by maternally deposited germ plasm, which is packaged into ribonucleoprotein complex in oocytes and inherited into PGCs-fated cells in embryos. However, the maternal factors regulating the assembly of germ plasm and PGC development remain poorly understood. In this study, we report that the maternal transcription factor Znf706 regulates the assembly of germ plasm factors into a granule-like structure localized perinuclearly in PGCs during migration. Maternal and zygotic mutants of znf706 (MZznf706) exhibit deficient germ plasm scattering at the early embryonic stage, decreased PGC numbers with some mislocation during PGC migration, and a lower female ratio in adulthood. Notably, the implementation of Znf706 CUT&Tag and RNA-seq on immature oocytes uncovers that Znf706 in stage I oocytes may promote transcription of several mitochondrial genes in addition to other functions. Hence, we propose that Znf706 is implicated in germ plasm assembly and PGC development in zebrafish.
    Keywords:  Germ plasm; Migration; Primordial germ cells; Zebrafish; Znf706
    DOI:  https://doi.org/10.1016/j.jgg.2024.11.007
  6. Curr Biol. 2024 Nov 15. pii: S0960-9822(24)01456-8. [Epub ahead of print]
    A tug-of-war between germ cell motility and intercellular bridges controls germline cyst formation in mice.
    Ezra W Levy, Isabella Leite, Bradley W Joyce, Stanislav Y Shvartsman, Eszter Posfai.
      Gametes in many species develop in cysts-clusters of germ cells formed by incomplete cytokinesis-that remain connected through intercellular bridges (ICBs). These connections enable sharing of cytoplasmic components between germ cells and, in the female germ line, enrich select cells in the cyst to become the oocyte(s). In mice, germline cysts of variable sizes are generated during embryonic development, thought to result from cyst fractures. Studies of fixed samples failed to capture fracture events, and thus, the mechanism remained elusive. Here, we use high-resolution live imaging of germ cells within their native tissue environment to visualize germline cyst dynamics. With this novel approach, we reveal a striking motile phenotype of gonad-resident germ cells and show that this randomly oriented cell-autonomous motile behavior during cyst formation underlies fracture events. Conversely, we show that stabilized ICBs help resist excessive fracturing. Additionally, we find that motility and thus fracture rates gradually decrease during development in a sex-dependent manner, completely ceasing by the end of cyst-forming divisions. These results lead to a model where the opposing activities of developmentally regulated cell motility and stable ICBs give rise to cysts of variable sizes. We corroborate these results by developing a model that uses experimentally measured fracture rates to simulate cyst formation and fracture and show that it can reproduce experimentally measured cyst sizes in both male and female. Understanding how variable cysts form will enable further studies of mammalian oocyte selection and establishment of the ovarian reserve.
    Keywords:  Oogonia; cell motility; cyst; cytokinesis; germline; intercellular bridge; live imaging; mouse; ovary
    DOI:  https://doi.org/10.1016/j.cub.2024.10.062
  7. Cell Death Discov. 2024 Nov 17. 10(1): 472
    DDX3 is critical for female fertility via translational control in oogenesis.
    Shang-Yu Tsai, Chih-Hung Lin, Yu-Ting Jiang, Guo-Jen Huang, Haiwei Pi, Hsin-Yuan Hung, Woan-Yuh Tarn, Ming-Chih Lai.
      DEAD-box RNA helicase 3 (DDX3) and its homologs play a vital role in translation initiation by unwinding secondary structures of selected mRNAs. The human DDX3 gene is located on the sex chromosomes, so there are DDX3X and DDX3Y. DDX3X is ubiquitously expressed in almost all tissues and critical for embryonic development, whereas DDX3Y is only expressed in the testis and essential for male fertility. Drosophila belle (bel) is the single ortholog of DDX3, and mutations in bel cause male and female infertility. Using Drosophila bel mutants and Ddx3x conditional knockout (cKO) mice, we confirmed the pivotal role of DDX3 in female fertility and ovarian development. Drosophila bel mutants exhibited female infertility and immature egg chambers. Consistently, oocyte-specific Ddx3x knockout in mice resulted in female infertility and impaired oogenesis. We further found that immature egg chambers in Drosophila bel mutants and impaired follicular development in oocyte-specific Ddx3x cKO mice were caused by excessive apoptosis. We also identified a set of DDX3 target genes involved in oocyte meiosis and maturation and demonstrated that DDX3 is involved in their translation in human cells. Our results suggest that DDX3 is critical for female fertility via translational control in oogenesis.
    DOI:  https://doi.org/10.1038/s41420-024-02242-6
  8. Zygote. 2024 Nov 18. 1-8
    Oocyte competence develops: nuclear maturation synchronously with cytoplasm maturation.
    Hossein Torkashvand, Ronak Shabani, Tayebe Artimani, Iraj Amiri, Shamim Pilehvari, Leila Torkashvand, Rana Mehdizadeh, Mehdi Mehdizadeh.
      Human oocyte maturation is a lengthy process that takes place over the course of which oocytes gain the inherent ability to support the next developmental stages in a progressive manner. This process includes intricate and distinct events related to nuclear and cytoplasmic maturation. Nuclear maturation includes mostly chromosome segregation, whereas rearrangement of organelles, storage of mRNAs and transcription factors occur during cytoplasmic maturation.Human oocyte maturation, both in vivo and in vitro, occurs through a process that is not yet fully understood. However, it is believed that the second messenger, cyclic adenosine monophosphate (cAMP), plays a pivotal role in the upkeep of the meiotic blocking of the human oocyte. Relatively high levels of cAMP in the human oocyte are required to maintain meiosis blocked, whereas lower levels of cAMP in the oocyte enable meiosis to resume. Oocyte cAMP concentration is controlled by a balance between adenylate cyclase and phosphodiesterases, the enzymes responsible for cAMP generation and breakdown.In addition to nuclear maturation, the female gamete requires a number of complicated structural and biochemical modifications in the cytoplasmic compartment to be able to fertilize normally. According to ultrastructural studies, during the transition from the germinal vesicle stage to metaphase II (MII), several organelles reorganize their positions. The cytoskeletal microfilaments and microtubules found in the cytoplasm facilitate these movements and regulate chromosomal segregation.The aim of this review is to focus on the nuclear and cytoplasmic maturation by investigating the changes that take place in the process of oocytes being competent for development.
    Keywords:  cytoplasmic maturation; development; meiosis; nuclear maturation; oocytes
    DOI:  https://doi.org/10.1017/S0967199424000169
  9. Development. 2024 Nov 22. pii: dev.202655. [Epub ahead of print]
    ARPP19 phosphorylation site evolution and the switch in cAMP control of oocyte maturation in vertebrates.
    Ferdinand Meneau, Pascal Lapébie, Enrico Maria Daldello, Tran Le, Sandra Chevalier, Sarah Assaf, Evelyn Houliston, Catherine Jessus, Marika Miot.
      cAMP-PKA signaling initiates the critical process of oocyte meiotic maturation in many animals, but inhibits it in vertebrates. To address this "cAMP paradox", we exchanged the key PKA substrate, ARPP19, between representative species, the vertebrate Xenopus and the cnidarian Clytia, comparing its phosphorylation and function. We found that as in Xenopus, Clytia maturing oocytes undergo ARPP19 phosphorylation on a highly conserved Gwl site, which inhibits PP2A and promotes M-phase entry. In contrast, despite a PKA phosphorylation signature motif recognisable across most animals, Clytia ARPP19 was only poorly phosphorylated by PKA in vitro and in vivo. Furthermore, unlike Xenopus ARPP19, exogenous Clytia ARPP19 did not delay Xenopus oocyte maturation. We conclude that in Clytia ARPP19 does not intervene in oocyte maturation initiation because of both poor recognition by PKA and the absence of effectors that mediate vertebrate oocyte prophase arrest. We propose that ancestral ARPP19 phosphorylated by Gwl has retained a key role in M-phase across eukaryotes and it has acquired new functions during animal evolution mediated by enhanced PKA phosphorylation, allowing co-option into oocyte maturation regulation in the vertebrate lineage.
    Keywords:   Clytia ; Xenopus ; ARPP19; Meiotic division; Oocyte; PKA
    DOI:  https://doi.org/10.1242/dev.202655
  10. Biochimie. 2024 Nov 20. pii: S0300-9084(24)00259-1. [Epub ahead of print]
    The completing of the second meiotic division by MII mouse oocytes correlates with the positioning of F-actin and mitochondria in the ooplasm.
    Yana A Ryabukha, Olga V Zatsepina, Yury P Rubtsov.
      Actin filaments play an essential role in the process of oocyte maturation and completion of meiosis. However, whether the localization of F-actin in the ooplasm is associated with normal completion of the second meiotic division remains unclear. Mitochondrial distribution is another important parameter correlating directly with MII oocyte capacity to finalize meiosis. Our objective was to examine the role of actin microfilaments in the distribution of mitochondria and, respectively, Metaphase II (MII) oocytes meiotic potential. We show monoclonal antibody-mediated inhibition of actin polymerization in young mouse oocytes, reduction of the amount of F-actin, and induction of mitochondrial clustering induced by antibody treatment. Similar phenotype, even in untreated eggs, was observed in in vitro oocyte aging experiments. Observed changes correlate with reduced ability of MII oocytes to extrude the second polar body and form the pronuclei. Changes in colocalization of F-actin and mitochondria likely resulted from disturbed cytoskeleton architecture. The perturbations in the amount of F-actin and its distribution largely coincide with mitochondrial redistribution. Based on these data, we suggest actin microfilament's participation in redistribution of mitochondria during MII oocyte aging in vitro. Accordingly, patterning of F-actin is indicative of high rate of the completed second meiotic division. These results help evaluating oocyte's quality and choosing optimal time between placement into culture and in vitro fertilization.
    Keywords:  F-actin; in vitro aging; mitochondria; oocytes; the second meiotic division
    DOI:  https://doi.org/10.1016/j.biochi.2024.11.004
  11. Reprod Biol Endocrinol. 2024 Nov 15. 22(1): 146
    Analysis of single-cell RNA sequencing in human oocytes with diminished ovarian reserve uncovers mitochondrial dysregulation and translation deficiency.
    Xin Li, Xingwu Wu, Hui Zhang, Peipei Liu, Leizhen Xia, Nana Zhang, Lifeng Tian, Zengming Li, Jing Lu, Yan Zhao, Jun Tan.
       BACKGROUND: Diminished ovarian reserve (DOR) is clinically characterized by a decrease in the number of available ovarian follicles and a decline in the quality of oocytes, accompanied by hormonal changes. Low quality of DOR oocyte leads to impaired embryo development, an increased risk of aneuploid pregnancies and miscarriages. However, the specific pathogenic mechanism remains unclear, posing a significant challenge for assisted reproductive technology.
    METHODS: For the first time, our study employed single-cell RNA sequencing to reveal the altered transcriptomic landscape of DOR oocytes at GV stage after ovarian stimulation. Differentially expressed genes analysis (DEGs), functional enrichment analysis, weighted gene co-expression network analysis (WGCNA) and protein-protein interactions network analysis were performed.
    RESULTS: We found 132 up-regulated genes and 466 down-regulated genes in DOR oocytes, with the down-regulated genes primarily enriched in mitochondrial function and translation. Hub genes, identified through integrated analysis of WGCNA and DEGs, were further validated in DOR and control oocytes using RT-qPCR. By utilizing hub genes and employing transcription factor enrichment tools, it had been predicted that pleomorphic adenoma gene 1 (PLAG1) played a crucial role as a transcriptional regulatory factor in DOR oocytes. Additionally, we conformed the PLAG1-IGF2 axis was dysregulated in DOR oocytes.
    CONCLUSIONS: Transcriptome analysis revealed that DOR oocytes exhibited mitochondrial dysfunction and translational defects, and the PLAG1-IGF2 axis might be a potential contributor for the low quality of DOR oocytes.
    Keywords:   IGF2 ; PLAG1 ; DOR; Mitochondrial function; Oocyte; Translation
    DOI:  https://doi.org/10.1186/s12958-024-01321-8
  12. bioRxiv. 2024 Nov 09. pii: 2023.12.06.570457. [Epub ahead of print]
    Population size interacts with reproductive longevity to shape the germline mutation rate.
    Luke Zhu, Annabel Beichman, Kelley Harris.
      Mutation rates vary across the tree of life by many orders of magnitude, with lower mutation rates in species that reproduce quickly and maintain large effective population sizes. A compelling explanation for this trend is that large effective population sizes facilitate selection against weakly deleterious "mutator alleles" such as variants that interfere with the molecular efficacy of DNA repair. However, in multicellular organisms, the relationship of the mutation rate to DNA repair efficacy is complicated by variation in reproductive age. Long generation times leave more time for mutations to accrue each generation, and late reproduction likely amplifies the fitness consequences of any DNA repair defect that creates extra mutations in the sperm or eggs. Here, we present theoretical and empirical evidence that a long generation time amplifies the strength of selection for low mutation rates in the spermatocytes and oocytes. This leads to the counterintuitive prediction that the species with the highest germline mutation rates per generation are also the species with most effective mechanisms for DNA proofreading and repair in their germ cells. In contrast, species with different generation times accumulate similar mutation loads during embryonic development. Our results parallel recent findings that the longest-lived species have the lowest mutation rates in adult somatic tissues, potentially due to selection to keep the lifetime mutation load below a harmful threshold.
    Significance Statement: All cells accumulate mutations due to DNA damage and replication errors. When mutations occur in germ tissues including sperm, eggs, and the early embryo, they create changes in the gene pool that can be passed down to future generations. Here, we examine how rates of germline mutations vary within and between mammalian species, and we find that species which reproduce at older ages tend to accumulate fewer mutations per year in their sperm and eggs. This finding suggests that the evolution of humans' long reproductive lifespan created evolutionary pressure to improve the fidelity of DNA maintenance in germ tissues, paralleling the pressure to avoid accumulating too many mutations in the body over a long lifespan.
    DOI:  https://doi.org/10.1101/2023.12.06.570457
  13. Reproduction. 2024 Nov 01. pii: REP-24-0271. [Epub ahead of print]
    Non-canonical spatial organization of heterochromatin in mouse preimplantation embryos.
    Amelie Bonnet-Garnier, Katia Ancelin.
      Spatial genome organization refers to the conformation of the chromosomes and their relative positioning within the nucleus. In mammals, fertilization entails intense chromatin remodeling of parental genomes, as well as large-scale structural changes in nuclear organization of the newly formed zygote over the first two cell cleavages. The molecular characteristics, mechanisms and functionality of spatial genome organization during the early steps of development in mouse have been extensively studied and will be presented in this review, with a specific focus on heterochromatin. Concomitantly to maturation of genomic architecture, the embryonic genome activation occurs in transient waves of transcription. Here, we will also discuss the putative link between heterochromatin organization and the regulation of genome expression.
    DOI:  https://doi.org/10.1530/REP-24-0271
  14. Dev Cell. 2024 Nov 15. pii: S1534-5807(24)00637-3. [Epub ahead of print]
    Lysosomal catabolic activity promotes the exit of murine totipotent 2-cell state by silencing early-embryonic retrotransposons.
    Hao Wu, Lanrui Cao, Xinpeng Wen, Jiawei Fan, Yuan Wang, Heyong Hu, Shuyan Ji, Yinli Zhang, Cunqi Ye, Wei Xie, Jin Zhang, Haoxing Xu, Xudong Fu.
      During mouse preimplantation development, a subset of retrotransposons/genes are transiently expressed in the totipotent 2-cell (2C) embryos. These 2C transcripts rapidly shut down their expression beyond the 2C stage of embryos, promoting the embryo to exit from the 2C stage. However, the mechanisms regulating this shutdown remain unclear. Here, we identified that lysosomal catabolism played a role in the exit of the totipotent 2C state. Our results showed that the activation of embryonic lysosomal catabolism promoted the embryo to exit from the 2C stage and suppressed 2C transcript expression. Mechanistically, our results indicated that lysosomal catabolism suppressed 2C transcripts through replenishing cellular amino-acid levels, thereby inactivating transcriptional factors TFE3/TFEB and abolishing their transcriptional activation of 2C retrotransposons, MERVL (murine endogenous retrovirus-L)/MT2_Mm. Collectively, our study identified that lysosomal activity modulated the transcriptomic landscape and development in mouse embryos and identified an unanticipated layer of transcriptional control on early-embryonic retrotransposons from lysosomal signaling.
    Keywords:  2-cell-like cells; lysosomal signaling; retrotransposons; totipotency
    DOI:  https://doi.org/10.1016/j.devcel.2024.10.018
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