Project description:Growing mammalian oocytes accumulate substantial amounts of RNA, most of which are degraded during the subsequent maturation stage. The growth-to-maturation transition begins with germinal vesicle breakdown (GVBD, envisioned as nuclear envelope breakdown) and is critical for oocyte quality. However, the concomitant changes in the transcriptome during GVBD as well as the underlying machinery remained unclear. Here, we report that an RNA exosome-associated RNase, EXOSC10, sculpts the transcriptome at multiple level to facilitate the oocyte growth-to-maturation transition. We establish an oocyte-specific knockout of Exosc10 in mice using CRISPR/Cas9 and find female subfertility due to failed GVBD. By performing single oocyte RNA-seq in different ways, we document dysregulated transcriptomes, unsuccessfully processed rRNAs in mutant oocytes, and many up-regulated RNAs that encode proteins important for endomembrane trafficking, meiotic cell cycle and RNA metabolism. EXOSC10-depleted oocytes have impaired endomembrane components including endosome, lysosome, ER and Golgi. In addition, CDK1 fails to be activated possibly due to persistent WEE1 activity, which blocked lamina phosphorylation and disassembly in mutant oocytes. Collectively, we propose that EXOSC10 promotes the growth-to-maturation transition in mouse oocytes by degrading mRNAs that encode growth-phase factors and sculpting the transcriptome to support the maturation phase of oogenesis.
Project description:EXOSC10 is a catalytic subunit of the nuclear RNA exosome with an exoribonuclease activity. The enzyme processes and degrades different classes of RNAs. To delineate the role of EXOSC10 during oocyte growth, specific Exosc10 inactivation was performed in the oocytes from the primordial follicle stage onward using the Gdf9-iCre; Exosc10f/- mouse model (Exosc10cKO(Gdf9)). Exosc10cKO(Gdf9) female mice are infertile. The onset of puberty and the estrus cycle in mutants are initially normal and ovaries contain all follicle classes. By the age of eight weeks, vaginal smears reveal irregular estrus cycles and mutant ovaries display a complete depletion of follicles. Mutant oocytes retrieved from the oviduct are degenerated, sometimes showing an enlarged polar body which may reflect a defective first meiotic division. Under fertilization conditions, the mutant oocytes do not enter into an embryonic development process. Furthermore, we conducted a comparative proteome analysis of wild type and Exosc10 knockout mouse ovaries and identified EXOSC10-dependent proteins involved in many biological processes, such as meiotic cell cycle progression and oocyte maturation. Our results unambiguously demonstrate an essential role for EXOSC10 in oogenesis and may serve as a model for primary ovarian insufficiency in humans.
Project description:Oocyte maturation is accompanied by a transition from mRNA stability to instability. We investigated the role of DCP1A and DCP2, proteins responsible for mRNA decapping, in mRNA destabilization during mouse oocyte maturation. siRNA-mediated knockdown of both Dcp1a and Dcp2 transcripts prior to initiation of maturation inhibited the maturation-associated increase of DCP1A and DCP2, stabilized a set of maternal mRNAs that are normally degraded during maturation, and inhibited development beyond the 2-cell stage, likely a consequence of failure to activate fully the zygotic genome. Total RNA from 30 MII eggs was used in each sample. Three independent biological replicates were analyzed for each condition.
Project description:Oocyte maturation is accompanied by a transition from mRNA stability to instability. We investigated the role of DCP1A and DCP2, proteins responsible for mRNA decapping, in mRNA destabilization during mouse oocyte maturation. siRNA-mediated knockdown of both Dcp1a and Dcp2 transcripts prior to initiation of maturation inhibited the maturation-associated increase of DCP1A and DCP2, stabilized a set of maternal mRNAs that are normally degraded during maturation, and inhibited development beyond the 2-cell stage, likely a consequence of failure to activate fully the zygotic genome.
Project description:The sequences deposited within this study are for the analysis of the changing transcriptome during zebrafish oocyte maturation. This dataset will be used to study the differential expression of mRNAs during oocyte maturation and also mechanisms of RNA stability and degradation, transcription and polyadenylation. Sequences will be generated using polyA selection and then, after reverse transcription, generated into illumina libraries. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
Project description:During mammalian oocyte development, transcriptome undergoes accumulation in the oocyte growth phase and elimination in the oocyte maturation phase. At the transition point between growth and maturation, which is the germinal vesicle intact oocyte (GV), terminal uridylation labels RNA for degradation. In our study, we show that a small cohort of RNA are polyadenylated after tail uridylation (defined as uridylated-poly(A) RNA). Upon genetic depletion of DIS3L2 (Dis3l2cKO) in mouse oocytes, uridylated-poly(A) RNA is extensively stabilized and dominates the oocyte transcriptome, which results in increased transcriptome in Dis3l2cKO oocytes. Consequently, Dis3l2cKO female mice are infertile and almost all oocytes are arrested at the GV stage. Uridylated-poly(A) RNA generally has shorter poly(A) tails and lower translation activity. The uridylated-poly(A) RNA in Dis3l2cKO oocytes not only generates from the insufficient RNA degradation, but also comes from the tail dynamics of RNA. Our study demonstrates more possibilities of RNA fates after being terminally uridylated, and highlights the role of DIS3L2 in safeguarding the transcriptome by degrading uridylated-poly(A) RNA.
Project description:The genetic causes of oocyte meiotic deficiency (OMD), a form of primary infertility characterised by the production of immature oocytes, remain largely unexplored. Using whole exome sequencing, we found that 26% of a cohort of 23 subjects with OMD harboured the same homozygous nonsense pathogenic mutation in PATL2, a gene encoding a putative RNA-binding protein. Using Patl2 knockout mice, we confirmed that PATL2 deficiency disturbs oocyte maturation, since oocytes and zygotes exhibit morphological and developmental defects respectively. PATL2's amphibian orthologue is involved in the regulation of oocyte mRNA as a partner of CPEB. However, Patl2's expression profile throughout oocyte development in mice, alongside colocalisation experiments with Cpeb1, Msy2 and Ddx6 (three oocyte RNA-regulators) suggest an original role for Patl2 in Mammals. Accordingly, transcriptomic analysis of oocytes from WT and Patl2-/- animals demonstrated that in the absence of Patl2, expression levels of a select number of highly relevant genes involved in oocyte maturation and early embryonic development are deregulated. In conclusion, PATL2 is a novel actor of mammalian oocyte maturation whose invalidation causes OMD in humans.
Project description:In vitro oocyte maturation (IVM) holds great promise as a tool for enhancing clinical treatment of infertility, enhancing availability of non human primates for development of disease models, and facilitating endangered species preservation. However, IVM outcomes have remained significantly below success rates obtained using in vivo matured (VVM) oocytes from humans and non human primates. A cDNA array based analysis is presented, comparing the transcriptomes of VVM oocytes with IVM oocytes. We observe a small set of just 59 mRNAs that are differentially expressed between the two cell types. These mRNAs are related to cellular homeostasis, cell-cell interactions including growth factor and hormone stimulation and cell adhesion, and other functions such as mRNA stability and translation. Additionally, we observe in IVM oocytes overexpression of PLAGL1 and MEST, two maternally imprinted genes, indicating a possible interruption or loss of correct epigenetic programming. These results indicate that, under certain IVM conditions, oocytes that are molecularly highly similar to VVM oocytes can be obtained, however the interruption of normal oocyte-somatic cell interactions during the final hours of oocyte maturation may preclude the establishment of full developmental competence. Keywords: oocyte maturation Comparison of in vitro matured MII-stage oocytes (4 biological replicates) with in vivo matured MII-stage oocytes (4 biological replicates)
Project description:Oocyte maturation is the foundation for developing healthy individuals of mammals. Upon germinal vesicle breakdown, oocyte meiosis resumes and the synthesis of new transcripts ceases. To quantitatively profile the transcriptomic dynamics after meiotic resumption throughout the oocyte maturation, we generated transcriptome sequencing data with individual mouse oocytes at three main developmental stages: germinal vesicle (GV), metaphase I (MI), and metaphase II (MII). When clustering the sequenced oocytes, results showed that isoform-level expression analysis outperformed gene-level analysis, indicating isoform expression provided extra information that was useful in distinguishing oocyte stages. Comparing transcriptomes of the oocytes at the GV stage and the MII stage, in addition to identification of differentially expressed genes (DEGs), we detected many differentially expressed transcripts (DETs), some of which came from genes that were not identified as DEGs. When breaking down the isoform-level changes into alternative RNA processing events, we found the main source of isoform composition changes was the alternative usage of polyadenylation sites. With detailed analysis focusing on the alternative usage of 3'-UTR isoforms, we identified, out of 3810 tested genes, 512 (13.7%) exhibiting significant switches of 3'-UTR isoforms during the process of moues oocyte maturation. Altogether, our data and analyses suggest the importance of examining isoform abundance changes during oocyte maturation, and further investigation of the pervasive 3'-UTR isoform switches in the transition may deepen our understanding on the molecular mechanisms underlying mammalian early development.