Suppressing Nodal Signaling Activity Predisposes Ectodermal Differentiation of Epiblast Stem Cells

摘要

Summary: The molecular mechanism underpinning the specification of the ectoderm, a transient germ-layer tissue, during mouse gastrulation was examined here in a stem cell-based model. We captured a self-renewing cell population with enhanced ectoderm potency from mouse epiblast stem cells (EpiSCs) by suppressing Nodal signaling activity. The transcriptome of the Nodal-inhibited EpiSCs resembles that of the anterior epiblast of embryonic day (E)7.0 and E7.5 mouse embryo, which is accompanied by chromatin modifications that reflect the priming of ectoderm lineage-related genes for expression. Nodal-inhibited EpiSCs show enhanced ectoderm differentiation in vitro and contribute to the neuroectoderm and the surface ectoderm in postimplantation chimeras but lose the propensity for mesendoderm differentiation in vitro and in chimeras. Our findings show that specification of the ectoderm progenitors is enhanced by the repression of Nodal signaling activity, and the ectoderm-like stem cells provide an experimental model to investigate the molecular characters of the epiblast-derived ectoderm. : In this article, Liu and colleagues show that Nodal-inhibited epiblast stem cells can self-renew in vitro and display similar transcriptome compared with the ectoderm of late-gastrula embryo. Further analysis shows that inhibition of Nodal signaling predisposes the epigenome to ectoderm-associated status. Moreover, these Nodal-inhibited epiblast stem cells efficiently differentiate to ectodermal cells but not mesendoderm lineages. Keywords: nodal signaling, epiblast stem cells, transcriptome, histone modification, ectoderm propensity