Project description:In this study, we performed ChIP-seq of RNA polymerase II, phosphorylated RNA polymerase II and related epigenetic modifications to elucidate transcriptional activities of mouse oocytes and preimplantation embryos. Through analyzing epigenetic alterations of transgenically-modified growing oocytes, early embryos from aged female, and early embryos treated with drugs disturbing proteostasis, we identified critical roles of proteostasis in transcriptional regulation of mouse oocytes and early embryos.
Project description:In this study, we performed RNA-seq to elucidate how transcriptional activities of mouse oocytes and preimplantation embryos are regulated to control oocyte-to-embryo transition. Through analyzing transcriptome alterations of transgenically-modified growing oocytes, early embryos from aged female, early embryos treated with drugs disturbing proteostasis, and embryonic stem cells treated with drugs disturbing proteostasis, we identified critical roles of proteostasis in transcriptional regulation of mouse oocytes and early embryos.
Project description:Transcriptome analysis of oocytes and early embryos to demonstrate trancriptional regulation during mouse oocyte-to-embryo transition
Project description:Sex differences in liver gene expression are dictated by sex-differences in circulating growth hormone (GH) profiles. Presently, the pituitary hormone dependence of mouse liver gene expression was investigated on a global scale to discover sex-specific early GH response genes that might contribute to sex-specific regulation of downstream GH targets and to ascertain whether intrinsic sex-differences characterize hepatic responses to plasma GH stimulation. RNA expression analysis using 41,000-feature microarrays revealed two distinct classes of sex-specific mouse liver genes: genes subject to positive regulation (class-I) and genes subject to negative regulation by pituitary hormones (class-II). Genes activated or repressed in hypophysectomized (Hypox) mouse liver within 30-90min of GH pulse treatment at a physiological dose were identified as direct targets of GH action (early response genes). Intrinsic sex-differences in the GH responsiveness of a subset of these early response genes were observed. Notably, 45 male-specific genes, including five encoding transcriptional regulators that may mediate downstream sex-specific transcriptional responses, were rapidly induced by GH (within 30min) in Hypox male but not Hypox female mouse liver. The early GH response genes were enriched in 29 male-specific targets of the transcription factor Mef2, whose activation in hepatic stellate cells is associated with liver fibrosis leading to hepatocellular carcinoma, a male-predominant disease. Thus, the rapid activation by GH pulses of certain sex-specific genes is modulated by intrinsic sex-specific factors, which may be associated with prior hormone exposure (epigenetic mechanisms) or genetic factors that are pituitary-independent, and could contribute to sex-differences in predisposition to liver cancer or other hepatic pathophysiologies.
Project description:DNA methylation is a tightly regulated epigenetic mark associated with transcriptional repression. Next-generation sequencing of purified methylated DNA obtained from early Xenopus tropicalis embryos demonstrates that this genome is heavily methylated during blastula and gastrula stages. Although DNA methylation is largely absent from transcriptional start sites marked with histone H3 lysine 4 trimethylation (H3K4me3), we find both promoters and gene bodies of active genes robustly methylated. By contrast, DNA methylation is absent in large H3K27me3 domains, indicating these two repression pathways have different roles. Comparison with chromatin state maps of human ES cells reveals strong conservation of epigenetic makeup and gene regulation between the two systems. Strikingly, genes that are highly expressed in human pluripotent cells and in Xenopus embryos but not in differentiated cells exhibit relatively high methylation in both promoters and gene bodies in embryos. Therefore we tested the repressive potential of DNA methylation using transient and transgenic approaches and show that methylated promoters are robustly transcribed in blastula and gastrula-stage embryos, but not in oocytes or late embryos where methylated templates are repressed efficiently. These findings have implications for reprogramming and the epigenetic regulation of pluripotency and differentiation, suggesting a relatively open, pliable chromatin state in early embryos followed by re-established methylation-dependent transcriptional repression during organogenesis and differentiation. MethylCap (methylated DNA affinity capture with the MBD domain of MeCP2), 500mM and 700mM elution fractions of stage 9 (blastula) and stage 12.5 (gastrula) Xenopus tropicalis DNA