Project description:Splat-like 4 (Sall4) plays important roles in maintaining pluripotency of embryonic stem cells and in various developmental processes. Here, we find that the SALL4 null oocytes fail to undergo maturation to form fully-grown oocytes (FGOs) and subsequent meiosis resumption. We further discover that the loss of maternal SALL4 causes failure in establishment of DNA methylation. Moreover, we demonstrate that SALL4 modulates H3K4me3 and H3K27me3 modifications by regulating the expression of Kdm5b, Kdm6a and Kdm6b. Taken together, SALL4 plays pivotal roles in oocyte epigenetic maturation.
Project description:Splat-like 4 (Sall4) plays important roles in maintaining pluripotency of embryonic stem cells and in various developmental processes. Here, we find that the SALL4 null oocytes fail to undergo maturation to form fully-grown oocytes (FGOs) and subsequent meiosis resumption. We further discover that the loss of maternal SALL4 causes failure in establishment of DNA methylation. Moreover, we demonstrate that SALL4 modulates H3K4me3 and H3K27me3 modifications by regulating the expression of Kdm5b, Kdm6a and Kdm6b. Taken together, SALL4 plays pivotal roles in oocyte epigenetic maturation.
Project description:We optimised an in vitro culture model for mouse oocytes starting from immature oocytes to get mature oocytes and investigated the effect of oxygen concentrations on the cultured oocytes (5 % vs 20% oxygen). The cultured oocytes were size-selected in both conditions. We generated expression and methylation profiling (RNA-Seq, RRBS, PBAT) by high throughput sequencing from these size selected oocytes and compared the results with in vivo size oocytes. Our observations reveal changes in DNA methylation and transcripts between oocytes cultured in vitro with different oxygen concentrations and in vivo grown murine oocytes. Oocytes grown under 20% O2 had a higher correlation with in vivo oocytes for DNA methylation and transcription demonstrating that higher oxygen concentration is beneficial for the oocyte maturation in ex-vivo culture condition.
Project description:Erasure and subsequent re-instatement of DNA methylation in the germline, especially at imprinted CpG islands (CGIs), is crucial to embryogenesis in mammals. The mechanisms underlying DNA methylation establishment remain poorly understood, but a number of post-translational modifications of histones are implicated in antagonizing or recruiting the de novo DNA methylation complex. In mouse oogenesis, DNA methylation establishment occurs on a largely unmethylated genome and in non-dividing cells, making it a highly informative model for examining how histone modifications can shape the DNA methylome. Using a chromatin immunoprecipitation and genome-wide sequencing (ChIP-Seq) protocol optimized for low cell numbers and novel techniques for isolating primary and growing oocytes, profiles were generated for histone modifications implicated in promoting or inhibiting DNA methylation. CGIs destined for DNA methylation show reduced protective H3K4me2 and H3K4me3 in both primary and growing oocytes, while permissive H3K36me3 increases specifically at these CGIs in growing oocytes. Methylome profiling of oocytes deficient in H3K4 demethylases KDM1A or KDM1B indicated that removal of H3K4 methylation is necessary for proper methylation establishment at CGIs. This work represents the first systematic study performing ChIP-Seq in oocytes, and shows that histone remodeling in the mammalian oocyte helps direct de novo DNA methylation events.
Project description:Oocyte acquires developmental competence during its maturation. This stage is accompanied with large-scale alteration in transcription, and series of genome-wide epigenetic reprogramming, including de novo establishment of DNA methylation. However, our understanding of mechanisms regulating this process is limited. To investigate the role of Stella (Dppa3) in de novo methylation during mouse oogenesis, here we measured DNA methylation by RRBS and expression profiles by RNA-seq in PGCs and oocytes at serveral development stages, including genotypes of both Stella (Dppa3) +/- and Stella -/-.
Project description:In this study, we mapped modification of lysine 4 and lysine 27 of histone H3 genome-wide in a series of mouse embryonic stem cells (mESCs) varying in DNA methylation levels based on knock-out and reconstitution of DNA methyltransferases (DNMTs). We extend previous studies showing cross-talk between DNA methylation and histone modifications by examining a breadth of histone modifications, causal relationships, and direct effects. Our data shows a causal regulation of H3K27me3 at gene promoters as well as H3K27ac and H3K27me3 at tissue-specific enhancers. We also identify isoform differences between DNMT family members. This study provides a comprehensive resource for the study of the complex interplay between DNA methylation and histone modification landscape. Reduced representation bisulfite sequencing (RRBS) performed on wild-type, Dnmt triple knock-out (Dnmt1/3a/3b; TKO), Dnmt double knock-out (Dnmt3a/3b; DKO), and respective reconstitution mouse embryonic stem cell lines.
Project description:Through RNA-seq of wildtype and CFP1-deleted GV oocytes of different ages, zygotes and 2-cell embryos and whole genome bisulfite sequencing of GV oocytes, We show here that CFP1 is responsible for epigenetic maturation in oocytes. Deletion of CFP1 directly decreased histone H3K4 trimethylation and caused global down-regulation of gene expression in oocytes.These genes are involved in cytoplasmic lattice formation, maternal-zygotic transition and epigenetic maturation. Maternal CFP1-deleted oocytes had fewer CPLs in the cytoplasm and the organelles were severely aggregated, which further caused defects in α-tubulin polymerization and aneuploidy in meiosis II. The genome was less methylated and methylation of maternal DNA was impaired after CFP1 deletion. Therefore CFP1-deleted oocytes fail to complete epigenetic maturation as well as cytoplasmic maturation and nuclear maturation and unable to gain developmental competence during oogenesis.