Regulation of embryonic haematopoietic multipotency by EZH1

Nature. 2018 Jan 25;553(7689):506-510. doi: 10.1038/nature25435. Epub 2018 Jan 17.


All haematopoietic cell lineages that circulate in the blood of adult mammals derive from multipotent haematopoietic stem cells (HSCs). By contrast, in the blood of mammalian embryos, lineage-restricted progenitors arise first, independently of HSCs, which only emerge later in gestation. As best defined in the mouse, 'primitive' progenitors first appear in the yolk sac at 7.5 days post-coitum. Subsequently, erythroid-myeloid progenitors that express fetal haemoglobin, as well as fetal lymphoid progenitors, develop in the yolk sac and the embryo proper, but these cells lack HSC potential. Ultimately, 'definitive' HSCs with long-term, multilineage potential and the ability to engraft irradiated adults emerge at 10.5 days post-coitum from arterial endothelium in the aorta-gonad-mesonephros and other haemogenic vasculature. The molecular mechanisms of this reverse progression of haematopoietic ontogeny remain unexplained. We hypothesized that the definitive haematopoietic program might be actively repressed in early embryogenesis through epigenetic silencing, and that alleviating this repression would elicit multipotency in otherwise lineage-restricted haematopoietic progenitors. Here we show that reduced expression of the Polycomb group protein EZH1 enhances multi-lymphoid output from human pluripotent stem cells. In addition, Ezh1 deficiency in mouse embryos results in precocious emergence of functional definitive HSCs in vivo. Thus, we identify EZH1 as a repressor of haematopoietic multipotency in the early mammalian embryo.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation
  • Cell Lineage
  • Chromatin / genetics
  • Chromatin / metabolism
  • Embryonic Development
  • Embryonic Stem Cells / cytology*
  • Female
  • Gene Silencing*
  • Hematopoiesis*
  • Hematopoietic Stem Cells / cytology*
  • Humans
  • Lymphocytes / cytology*
  • Lymphocytes / metabolism
  • Mice
  • Multipotent Stem Cells / cytology*
  • Pluripotent Stem Cells / cytology
  • Polycomb Repressive Complex 2 / chemistry
  • Polycomb Repressive Complex 2 / deficiency
  • Polycomb Repressive Complex 2 / genetics
  • Polycomb Repressive Complex 2 / metabolism*


  • Chromatin
  • EZH1 protein, human
  • Ezh1 protein, mouse
  • Polycomb Repressive Complex 2