Project description:The integrity of chromatin, which provides a dynamic template for all DNA-related processes in eukaryotes, is maintained through replication-dependent and -independent assembly pathways. To address the role of replication-independent histone deposition, we deleted the histone H3.3 chaperone Hira in developing mouse oocytes. We show that chromatin of non-replicative developing oocytes is highly dynamic, and that lack of continuous H3.3/H4 deposition alters chromatin structure, resulting in increased DNase I sensitivity, the accumulation of DNA damage, and, ultimately, a severe fertility phenotype. On the molecular level, abnormal chromatin structure leads to a dramatic decrease in the dynamic range of gene expression, the appearance of spurious transcripts, and inefficient de novo DNA methylation. In contrast to the only minor transcriptional phenotype observed in mouse pluripotent cells, we unequivocally show the importance of histone replacement and chromatin homeostasis for transcriptional regulation and normal developmental progression in an in vivo context. RNA-Seq on 4 Hiraf/f and 4 Hiraf/f, Zp3-Cre single MII oocytes.
Project description:The integrity of chromatin, which provides a dynamic template for all DNA related processes in eukaryotes, is maintained through replication dependent and independent assembly pathways. To address the role of replication independent histone deposition, we deleted the histone H3.3 chaperone Hira in developing mouse oocytes. We show that chromatin of non-replicative developing oocytes is highly dynamic, and that lack of continuous H3.3/H4 deposition alters chromatin structure, resulting in increased DNase I sensitivity, the accumulation of DNA damage, and, ultimately, a severe fertility phenotype. On the molecular level, abnormal chromatin structure leads to a dramatic decrease in the dynamic range of gene expression, the appearance of spurious transcripts, and inefficient de novo DNA methylation. In contrast to the only minor transcriptional phenotype observed in mouse pluripotent cells, we unequivocally show the importance of histone replacement and chromatin homeostasis for transcriptional regulation and normal developmental progression in an in vivo context. RNA-Seq on 4 Hiraf/f and 4 Hiraf/f, Gdf9-Cre+ single MII oocytes
Project description:With the exception of imprinted genes and certain repeats, DNA methylation is globally erased during pre-implantation development. Recent studies have suggested that Tet3-mediated oxidation of 5-methylcytosine (5mC) and DNA replication-dependent dilution both contribute to global paternal DNA demethylation, but demethylation of the maternal genome occurs via replication. Here we present genome-scale DNA methylation maps for both the paternal and maternal genomes of Tet3-depleted and/or DNA replication-inhibited zygotes. In both genomes, we found that inhibition of DNA replication blocks DNA demethylation independently from Tet3 function, and that Tet3 facilitates DNA demethylation by coupling with DNA replication. For both, our data indicate that replication-dependent dilution is the major contributor to demethylation, but Tet3 plays an important role, particularly at certain loci. Our study therefore both defines the respective functions of Tet3 and DNA replication in paternal DNA demethylation and reveals an unexpected contribution of Tet3 to demethylation of the maternal genome. In this data set, we include RNA-Seq data of mouse 2-cell embryos and blastocysts derived from both wildtype and Tet3-null oocytes
Project description:Polyadenylated RNA from individual germinal vesicle and metaphase II ooyctes was amplified and processed for Illumina sequencing. Increases in polyadenylated transcript abundance were observed and are likely due to cytoplasmic polyadenylation. Transcriptomic analysis of GV and MII bovine oocytes.
Project description:There is massive destruction of transcripts during maturation of mouse oocytes. The objective of this project was to identify and characterize the transcripts that are degraded versus those that are stable during the transcriptionally silent germinal vesicle (GV)-stage to metaphase II (MII)-stage transition using the microarray approach. A system for oocyte transcript amplification using both internal and 3'-poly(A) priming was utilized to minimize the impact of complex variations in transcript polyadenylation prevalent during this transition. Transcripts were identified and quantified using Affymetrix Mouse Genome 430 v2.0 GeneChip. The significantly changed and stable transcripts were analyzed using Ingenuity Pathways Analysis and GenMAPP/MAPPFinder to characterize the biological themes underlying global changes in oocyte transcripts during maturation. It was concluded that the destruction of transcripts during the GV to MII transition is a selective rather than promiscuous process in mouse oocytes. In general, transcripts involved in processes that are associated with meiotic arrest at the GV-stage and the progression of oocyte maturation, such as oxidative phosphorylation, energy production, and protein synthesis and metabolism, were dramatically degraded. In contrast, transcripts encoding participants in signaling pathways essential for maintaining the unique characteristics of the MII-arrested oocyte, such as those involved in protein kinase pathways, were the most prominent among those stables. Experiment Overall Design: Comparison immature GV-stage oocyte (3 biological replicates) with mature MII-stage oocytes (3 biological replicates)
Project description:The comparison of trancriptomes was part of the study by Pfender, Kuznetsov, Pasternak et al, titled: "Live imaging RNAi screen reveals genes essential for meiosis in mammalian oocytes". The goal was to check if the oocytes cultured in vitro in follicles (for RNAi studies) correspond to real gametes obtained directly from mice (in vivo). Apart from functional experiments showing that they can be fertilized and develop into an embryo, we also compared transcriptomes of those oocytes. 3 samples of 50 oocytes were collected for both groups of in vitro and in vivo grown oocytes.
Project description:The oocytes of many species, both invertebrate and vertebrate, contain a large collection of localized determinants in the form of proteins and translationally inactive maternal mRNAs. However, it is unknown whether mouse oocytes contain localized MmRNA determinants and what mechanisms might be responsible for their control. We collected intact MII oocytes, enucleated MII oocyte cytoplasts (with the spindle removed), and spindle-chromosome complexes which had been microsurgically removed. RNA was extracted, amplified, labeled, and applied to microarrays to determine if any MmRNA determinants were localized to the SCC. We used microarrays to determine whether maternal mRNAs in mouse oocytes are enriched in the meiotic spindle
Project description:Postovulatory aging leads to the decline in oocyte quality and subsequent impairment of embryonic development, thereby reducing the success rates of assisted reproductive technology (ART). Nevertheless, potential preventative strategies to improve aging oocytes quality and the associated underlying mechanisms warrant further investigation. In this study, we identify cordycepin, an natural nucleoside analogue, as having the potential to restore the postovulatory aging-induced decline in oocyte quality, including aspects such as oocyte fragmentation, embryonic developmental competence, spindle/chromosomes morphology and mitochondrial function. Proteomic and RNA sequencing analyses revealed that cordycepin inhibited the degradation of several crucial maternal proteins and mRNAs caused by aging. Mechanistically, cordycepin was found to suppress the elevation of DCP1A protein levels by inhibiting polyadenylation during postovulatory aging, consequently impeding the decapping of maternal mRNAs. In humans, the increased degradation of DCP1A and total mRNA during aging was also inhibited by cordycepin. Collectively, our findings demonstrate that cordycepin may prevent postovulatory aging of mammalian oocytes by inhibition of maternal mRNAs degradation via DCP1A polyadenylation suppression, thereby promoting the successful rates of ART procedure.
Project description:To elucidate some of the tools involved in early embryonic reprogramming, the levels of gene transcripts believed to be of importance to epigenetic modifications, and chromatin remodeling were detected by oligonucleotide microarrays in in vivo matured MII oocytes and compared with fully in vivo grown GV oocytes.