RESUMO
Oocytes are among the longest-lived cells in the body and need to preserve their cytoplasm to support proper embryonic development. Protein aggregation is a major threat for intracellular homeostasis in long-lived cells. How oocytes cope with protein aggregation during their extended life is unknown. Here, we find that mouse oocytes accumulate protein aggregates in specialized compartments that we named endolysosomal vesicular assemblies (ELVAs). Combining live-cell imaging, electron microscopy, and proteomics, we found that ELVAs are non-membrane-bound compartments composed of endolysosomes, autophagosomes, and proteasomes held together by a protein matrix formed by RUFY1. Functional assays revealed that in immature oocytes, ELVAs sequester aggregated proteins, including TDP-43, and degrade them upon oocyte maturation. Inhibiting degradative activity in ELVAs leads to the accumulation of protein aggregates in the embryo and is detrimental for embryo survival. Thus, ELVAs represent a strategy to safeguard protein homeostasis in long-lived cells.
Assuntos
Vesículas Citoplasmáticas , Oócitos , Agregados Proteicos , Animais , Feminino , Camundongos , Autofagossomos , Vesículas Citoplasmáticas/metabolismo , Lisossomos/metabolismo , Oócitos/citologia , Oócitos/metabolismo , Complexo de Endopeptidases do Proteassoma , ProteóliseRESUMO
Mammalian oocytes are filled with poorly understood structures called cytoplasmic lattices. First discovered in the 1960s and speculated to correspond to mammalian yolk, ribosomal arrays, or intermediate filaments, their function has remained enigmatic to date. Here, we show that cytoplasmic lattices are sites where oocytes store essential proteins for early embryonic development. Using super-resolution light microscopy and cryoelectron tomography, we show that cytoplasmic lattices are composed of filaments with a high surface area, which contain PADI6 and subcortical maternal complex proteins. The lattices associate with many proteins critical for embryonic development, including proteins that control epigenetic reprogramming of the preimplantation embryo. Loss of cytoplasmic lattices by knocking out PADI6 or the subcortical maternal complex prevents the accumulation of these proteins and results in early embryonic arrest. Our work suggests that cytoplasmic lattices enrich maternally provided proteins to prevent their premature degradation and cellular activity, thereby enabling early mammalian development.
Assuntos
Oócitos , Proteínas , Gravidez , Animais , Feminino , Oócitos/metabolismo , Proteínas/metabolismo , Embrião de Mamíferos/metabolismo , Citoesqueleto , Ribossomos , Desenvolvimento Embrionário , MamíferosRESUMO
Cellular homeostasis requires the robust control of biomolecule concentrations, but how do millions of mRNAs coordinate their stoichiometries in the face of dynamic translational changes? Here, we identified a two-tiered mechanism controlling mRNA:mRNA and mRNA:protein stoichiometries where mRNAs super-assemble into condensates with buffering capacity and sorting selectivity through phase-transition mechanisms. Using C. elegans oogenesis arrest as a model, we investigated the transcriptome cytosolic reorganization through the sequencing of RNA super-assemblies coupled with single mRNA imaging. Tightly repressed mRNAs self-assembled into same-sequence nanoclusters that further co-assembled into multiphase condensates. mRNA self-sorting was concentration dependent, providing a self-buffering mechanism that is selective to sequence identity and controls mRNA:mRNA stoichiometries. The cooperative sharing of limiting translation repressors between clustered mRNAs prevented the disruption of mRNA:repressor stoichiometries in the cytosol. Robust control of mRNA:mRNA and mRNA:protein stoichiometries emerges from mRNA self-demixing and cooperative super-assembly into multiphase multiscale condensates with dynamic storage capacity.
Assuntos
Condensados Biomoleculares , Caenorhabditis elegans , RNA Mensageiro , Animais , Caenorhabditis elegans/citologia , Caenorhabditis elegans/metabolismo , Oogênese , Biossíntese de Proteínas , Transporte de RNA , RNA Mensageiro/química , RNA Mensageiro/metabolismo , Proteínas/química , Proteínas/metabolismo , Condensados Biomoleculares/química , Condensados Biomoleculares/metabolismoRESUMO
Mouse germline cysts, on average, develop into six oocytes supported by 24 nurse cells that transfer cytoplasm and organelles to generate a Balbiani body. We showed that between E14.5 and P5, cysts periodically activate some nurse cells to begin cytoplasmic transfer, which causes them to shrink and turnover within 2 days. Nurse cells die by a programmed cell death (PCD) pathway involving acidification, similar to Drosophila nurse cells, and only infrequently by apoptosis. Prior to initiating transfer, nurse cells co-cluster by scRNA-seq with their pro-oocyte sisters, but during their final 2 days, they cluster separately. The genes promoting oocyte development and nurse cell PCD are upregulated, whereas the genes that repress transfer, such as Tex14, and oocyte factors, such as Nobox and Lhx8, are under-expressed. The transferred nurse cell centrosomes build a cytocentrum that establishes a large microtubule aster in the primordial oocyte that organizes the Balbiani body, defining the earliest oocyte polarity.
Assuntos
Linhagem da Célula , Cistos , Oócitos , Animais , Apoptose , Crescimento Celular , Cistos/genética , Cistos/metabolismo , Citoplasma/metabolismo , Drosophila melanogaster , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Camundongos , Oócitos/citologia , Oócitos/metabolismo , Ovário/citologia , Ovário/embriologia , Ovário/metabolismoRESUMO
Molecular mechanisms of ovarian aging and female age-related fertility decline remain unclear. We surveyed the single-cell transcriptomic landscape of ovaries from young and aged non-human primates (NHPs) and identified seven ovarian cell types with distinct gene-expression signatures, including oocyte and six types of ovarian somatic cells. In-depth dissection of gene-expression dynamics of oocytes revealed four subtypes at sequential and stepwise developmental stages. Further analysis of cell-type-specific aging-associated transcriptional changes uncovered the disturbance of antioxidant signaling specific to early-stage oocytes and granulosa cells, indicative of oxidative damage as a crucial factor in ovarian functional decline with age. Additionally, inactivated antioxidative pathways, increased reactive oxygen species, and apoptosis were observed in granulosa cells from aged women. This study provides a comprehensive understanding of the cell-type-specific mechanisms underlying primate ovarian aging at single-cell resolution, revealing new diagnostic biomarkers and potential therapeutic targets for age-related human ovarian disorders.
Assuntos
Envelhecimento/genética , Ovário/fisiologia , Análise de Célula Única/métodos , Transcriptoma , Idoso , Animais , Antioxidantes/metabolismo , Apoptose/fisiologia , Atlas como Assunto , Biomarcadores , Linhagem Celular Tumoral , Feminino , Células da Granulosa/metabolismo , Humanos , Macaca fascicularis , Oócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/fisiologiaRESUMO
Asymmetric division in female meiosis creates selective pressure favoring selfish centromeres that bias their transmission to the egg. This centromere drive can explain the paradoxical rapid evolution of both centromere DNA and centromere-binding proteins despite conserved centromere function. Here, we define a molecular pathway linking expanded centromeres to histone phosphorylation and recruitment of microtubule destabilizing factors, leading to detachment of selfish centromeres from spindle microtubules that would direct them to the polar body. Exploiting centromere divergence between species, we show that selfish centromeres in two hybrid mouse models use the same molecular pathway but modulate it differently to enrich destabilizing factors. Our results indicate that increasing microtubule destabilizing activity is a general strategy for drive in both models, but centromeres have evolved distinct mechanisms to increase that activity. Furthermore, we show that drive depends on slowing meiotic progression, suggesting that selfish centromeres can be suppressed by regulating meiotic timing.
Assuntos
Centrômero/genética , Meiose , Animais , Segregação de Cromossomos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microtúbulos/metabolismo , Oócitos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismoRESUMO
Mammalian eggs (oocytes) are formed during fetal life and establish associations with somatic cells to form primordial follicles that create a store of germ cells (the primordial pool). The size of this pool is influenced by key events during the formation of germ cells and by factors that influence the subsequent activation of follicle growth. These regulatory pathways must ensure that the reserve of oocytes within primordial follicles in humans lasts for up to 50 years, yet only approximately 0.1% will ever be ovulated with the rest undergoing degeneration. This review outlines the mechanisms and regulatory pathways that govern the processes of oocyte and follicle formation and later growth, within the ovarian stroma, through to ovulation with particular reference to human oocytes/follicles. In addition, the effects of aging on female reproductive capacity through changes in oocyte number and quality are emphasized, with both the cellular mechanisms and clinical implications discussed. Finally, the details of current developments in culture systems that support all stages of follicle growth to generate mature oocytes in vitro and emerging prospects for making new oocytes from stem cells are outlined.
Assuntos
Oócitos , Folículo Ovariano , Animais , Humanos , Feminino , Oócitos/fisiologia , Folículo Ovariano/metabolismo , Ovário/metabolismo , Oogênese/fisiologia , Mamíferos/fisiologia , EnvelhecimentoRESUMO
Development of the ovary or testis is required to establish reproductive competence. Gonad development relies on key cell fate decisions that occur early in embryonic development and are actively maintained. During gonad development, both germ cells and somatic cells proliferate extensively, a process facilitated by cell cycle regulation. This review focuses on the Cip/Kip family of cyclin-dependent kinase inhibitors (CKIs) in mouse gonad development. We particularly highlight recent single-cell RNA sequencing studies that show the heterogeneity of cyclin-dependent kinase inhibitors. This diversity highlights new roles for cell cycle inhibitors in controlling and maintaining female fertility.
Assuntos
Pontos de Checagem do Ciclo Celular/genética , Fertilidade/genética , Gônadas/crescimento & desenvolvimento , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Diferenciação Celular/genética , Gônadas/metabolismo , Camundongos , Processos de Determinação Sexual/genética , Análise de Célula ÚnicaRESUMO
The poly(A) tail is an essential structural component of mRNA required for the latter's stability and translation. Recent technologies have enabled transcriptome-wide profiling of the length and composition of poly(A) tails, shedding light on their overlooked regulatory capacities. Notably, poly(A) tails contain not only adenine but also uracil, cytosine, and guanine residues. These findings strongly suggest that poly(A) tails could encode a wealth of regulatory information, similar to known reversible RNA chemical modifications. This review aims to succinctly summarize our current knowledge on the composition, dynamics, and regulatory functions of RNA poly(A) tails. Given their capacity to carry rich regulatory information beyond the genetic code, we propose the concept of 'poly(A) tail epigenetic information' as a new layer of RNA epigenetic regulation.
RESUMO
Well-balanced and timed metabolism is essential for making a high-quality egg. However, the metabolic framework that supports oocyte development remains poorly understood. Here, we obtained the temporal metabolome profiles of mouse oocytes during in vivo maturation by isolating large number of cells at key stages. In parallel, quantitative proteomic analyses were conducted to bolster the metabolomic data, synergistically depicting the global metabolic patterns in oocytes. In particular, we discovered the metabolic features during meiotic maturation, such as the fall in polyunsaturated fatty acids (PUFAs) level and the active serine-glycine-one-carbon (SGOC) pathway. Using functional approaches, we further identified the key targets mediating the action of PUFA arachidonic acid (ARA) on meiotic maturation and demonstrated the control of epigenetic marks in maturing oocytes by SGOC network. Our data serve as a broad resource on the dynamics occurring in metabolome and proteome during oocyte maturation.
Assuntos
Meiose/fisiologia , Oócitos/metabolismo , Animais , Epigênese Genética/genética , Ácidos Graxos Insaturados/metabolismo , Feminino , Metaboloma/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Oogênese/genética , Oogênese/fisiologia , Proteoma/metabolismo , ProteômicaRESUMO
Genetic adaptations of organisms living in extreme environments are fundamental to our understanding of where life can evolve. Water is the single limiting parameter in this regard, yet when released in the oceans, the single-celled eggs of marine bony fishes (teleosts) have no means of acquiring it. They are strongly hyposmotic to seawater and lack osmoregulatory systems. Paradoxically, modern teleosts successfully release vast quantities of eggs in the extreme saline environment and recorded the most explosive radiation in vertebrate history. Here, we highlight key genetic adaptations that evolved to solve this paradox by filling the pre-ovulated eggs with water. The degree of water acquisition is uniquely prevalent to marine teleosts, permitting the survival and oceanic dispersal of their eggs.
Assuntos
Adaptação Fisiológica , Peixes , Animais , Peixes/genética , Adaptação Fisiológica/genética , Óvulo , Oceanos e Mares , Água do Mar , Evolução Biológica , Osmorregulação/genéticaRESUMO
Oocyte maturation and preimplantation embryo development are critical to successful pregnancy outcomes and the correct establishment and maintenance of genomic imprinting. Thanks to novel technologies and omics studies in human patients and mouse models, the importance of the proteins associated with the cytoplasmic lattices (CPLs), highly abundant structures found in the cytoplasm of mammalian oocytes and preimplantation embryos, in the maternal to zygotic transition is becoming increasingly evident. This review highlights the recent discoveries on the role of these proteins in protein storage and other oocyte cytoplasmic processes, epigenetic reprogramming, and zygotic genome activation (ZGA). A better comprehension of these events may significantly improve clinical diagnosis and pave the way for targeted interventions aiming to correct or mitigate female fertility issues and genomic imprinting disorders.
RESUMO
Nucleoporins (Nups) assemble nuclear pores that form the permeability barrier between nucleoplasm and cytoplasm. Nucleoporins also localize in cytoplasmic foci proposed to function as pore pre-assembly intermediates. Here, we characterize the composition and incidence of cytoplasmic Nup foci in an intact animal, C. elegans. We find that, in young non-stressed animals, Nup foci only appear in developing sperm, oocytes and embryos, tissues that express high levels of nucleoporins. The foci are condensates of highly cohesive FG repeat-containing nucleoporins (FG-Nups), which are maintained near their solubility limit in the cytoplasm by posttranslational modifications and chaperone activity. Only a minor fraction of FG-Nup molecules concentrate in Nup foci, which dissolve during M phase and are dispensable for nuclear pore assembly. Nucleoporin condensation is enhanced by stress and advancing age, and overexpression of a single FG-Nup in post-mitotic neurons is sufficient to induce ectopic condensation and organismal paralysis. We speculate that Nup foci are non-essential and potentially toxic condensates whose assembly is actively suppressed in healthy cells.
Assuntos
Complexo de Proteínas Formadoras de Poros Nucleares , Poro Nuclear , Masculino , Animais , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Poro Nuclear/genética , Poro Nuclear/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Sêmen/metabolismo , Núcleo Celular/metabolismo , Transporte Ativo do Núcleo CelularRESUMO
Recent studies have reported the differentiation of pluripotent cells into oocytes in vitro. However, the developmental competence of in vitro-generated oocytes remains low. Here, we perform a comprehensive comparison of mouse germ cell development in vitro over all culture steps versus in vivo with the goal to understand mechanisms underlying poor oocyte quality. We show that the in vitro differentiation of primordial germ cells to growing oocytes and subsequent follicle growth is critical for competence for preimplantation development. Systematic transcriptome analysis of single oocytes that were subjected to different culture steps identifies genes that are normally upregulated during oocyte growth to be susceptible for misregulation during in vitro oogenesis. Many misregulated genes are Polycomb targets. Deregulation of Polycomb repression is therefore a key cause and the earliest defect known in in vitro oocyte differentiation. Conversely, structurally normal in vitro-derived oocytes fail at zygotic genome activation and show abnormal acquisition of 5-hydroxymethylcytosine on maternal chromosomes. Our data identify epigenetic regulation at an early stage of oogenesis limiting developmental competence and suggest opportunities for future improvements.
Assuntos
Epigênese Genética , Oócitos , Feminino , Animais , Camundongos , Folículo Ovariano , Oogênese/genética , Células GerminativasRESUMO
The RNA-binding protein cytoplasmic polyadenylation element binding 1 (CPEB1) plays a fundamental role in regulating mRNA translation in oocytes. However, the specifics of how and which protein kinase cascades modulate CPEB1 activity are still controversial. Using genetic and pharmacological tools, and detailed time courses, we have re-evaluated the relationship between CPEB1 phosphorylation and translation activation during mouse oocyte maturation. We show that both the CDK1/MAPK and AURKA/PLK1 pathways converge on CPEB1 phosphorylation during prometaphase of meiosis I. Only inactivation of the CDK1/MAPK pathway disrupts translation, whereas inactivation of either pathway alone leads to CPEB1 stabilization. However, CPEB1 stabilization induced by inactivation of the AURKA/PLK1 pathway does not affect translation, indicating that destabilization and/or degradation is not linked to translational activation. The accumulation of endogenous CCNB1 protein closely recapitulates the translation data that use an exogenous template. These findings support the overarching hypothesis that the activation of translation during prometaphase in mouse oocytes relies on a CDK1/MAPK-dependent CPEB1 phosphorylation, and that translational activation precedes CPEB1 destabilization.
Assuntos
Meiose , Oócitos , Biossíntese de Proteínas , Fatores de Transcrição , Fatores de Poliadenilação e Clivagem de mRNA , Animais , Feminino , Camundongos , Aurora Quinase A/metabolismo , Aurora Quinase A/genética , Proteína Quinase CDC2/metabolismo , Proteína Quinase CDC2/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Ciclina B1/metabolismo , Ciclina B1/genética , Fatores de Poliadenilação e Clivagem de mRNA/metabolismo , Fatores de Poliadenilação e Clivagem de mRNA/genética , Oócitos/metabolismo , Oócitos/citologia , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas/genética , Transdução de Sinais , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genéticaRESUMO
Delivering molecular tools into oocytes is essential for developmental and reproductive biology. Microinjection, the conventional method, is equipment-intensive, often technically challenging, and low-yield, and is impractical in species with delicate oocytes or restricted spawning seasons. To overcome these limitations, we developed VitelloTag, a cost-effective, high-throughput system using vitellogenin-derived fusion proteins to enable efficient cargo delivery via receptor-mediated endocytosis. We demonstrate its utility by delivering Cas9/sgRNA complexes in two distantly related species for gene knockout.
RESUMO
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
In the meiotic prophase, programmed DNA double-strand breaks are repaired by meiotic recombination. Recombination-defective meiocytes are eliminated to preserve genome integrity in gametes. BRCA1 is a critical protein in somatic homologous recombination, but studies have suggested that BRCA1 is dispensable for meiotic recombination. Here we show that BRCA1 is essential for meiotic recombination. Interestingly, BRCA1 also has a function in eliminating recombination-defective oocytes. Brca1 knockout (KO) rescues the survival of Dmc1 KO oocytes far more efficiently than removing CHK2, a vital component of the DNA damage checkpoint in oocytes. Mechanistically, BRCA1 activates chromosome asynapsis checkpoint by promoting ATR activity at unsynapsed chromosome axes in Dmc1 KO oocytes. Moreover, Brca1 KO also rescues the survival of asynaptic Spo11 KO oocytes. Collectively, our study not only unveils an unappreciated role of chromosome asynapsis in eliminating recombination-defective oocytes but also reveals the dual functions of BRCA1 in safeguarding oocyte genome integrity.
Assuntos
Proteína BRCA1 , Proteínas de Ciclo Celular , Camundongos Knockout , Oócitos , Oócitos/metabolismo , Animais , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Feminino , Camundongos , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Meiose/genética , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia/deficiência , Quebras de DNA de Cadeia Dupla , Pareamento Cromossômico/genética , Endodesoxirribonucleases/metabolismo , Endodesoxirribonucleases/genética , Quinase do Ponto de Checagem 2/genética , Quinase do Ponto de Checagem 2/metabolismo , Proteínas de Ligação a Fosfato/metabolismo , Proteínas de Ligação a Fosfato/genética , Recombinação Genética , Recombinação Homóloga , Instabilidade GenômicaRESUMO
Transcriptional and post-transcriptional regulations control gene expression in most cells. However, critical transitions during the development of the female gamete relies exclusively on regulation of mRNA translation in the absence of de novo mRNA synthesis. Specific temporal patterns of maternal mRNA translation are essential for the oocyte progression through meiosis, for generation of a haploid gamete ready for fertilization and for embryo development. In this review, we will discuss how mRNAs are translated during oocyte growth and maturation using mostly a genome-wide perspective. This broad view on how translation is regulated reveals multiple divergent translational control mechanisms required to coordinate protein synthesis with progression through the meiotic cell cycle and with development of a totipotent zygote.
Assuntos
Oócitos , Biossíntese de Proteínas , Oócitos/metabolismo , Oócitos/crescimento & desenvolvimento , Humanos , Animais , Biossíntese de Proteínas/genética , RNA Mensageiro Estocado/genética , RNA Mensageiro Estocado/metabolismo , Feminino , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Oogênese/genética , Genoma/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Meiose/genéticaRESUMO
Parental diet is known to influence the offspring in an intergenerational manner, and this has been implicated in species adaptation and general health. Recent studies highlight the role of maternal long noncoding RNAs (lncRNAs) in serving as one of the 'memories' of maternal diet in regulating offspring development and predisposition to metabolic disease.