Silencing of developmental genes by H3K27me3 and DNA methylation reflects the discrepant plasticity of embryonic and extraembryonic lineages

摘要

Dear Editor, One of the most important topics in mammalian embryogenesis is the generation of multiple cell lineages. Briefly, one single-cell totipotent zygote develops into the inner cell mass (ICM) and trophectoderm (TE) at the blastocyst stage. Afterwards, the ICM further generates the epiblast cells and finally forms multiple somatic cell lineages, while the TE develops into extraembryonic ectoderm (ExE) cells and eventually forms the placental tissue. The highly ordered programming of mammalian embryo development is spatial-temporally regulated by epigenetic mechanisms. Previous work has revealed that the ICM and TE remain largely epigenetically indistinguishable,1, 2 even though there exist significant transcriptional distinctions. Recently we revealed the spatial-specific transcriptome of key development-related genes (DRGs) in mouse E7.0 gastrula, and we also noticed that these DRG-silenced gastrula regions possess distinct developmental potencies.3 However, whether there are any distinctions of epigenetic mechanisms underlying the region-specific distribution of DRGs in post implantation embryos and how these epigenetic distinctions contribute to the regionalized developmental potential in mouse embryos remain unclear.