Discovery of a new path for red blood cell generation in the mouse embryo

Abstract

Erythropoiesis occurs through several waves during embryonic development.Although the source of the primitive wave is well characterized, the origin of erythrocytes later in embryogenesis is less clear due to overlaps between the different erythroid waves. Using the miR144/451-GFP mouse model to track cells expressing the erythroid microRNAs miR144/451, we identified cells co-expressing VE-Cadherin and GFP in the yolk sac between E9.5 and E12. This suggested the existence of hemogenic endothelial cells committed to erythropoiesis (Ery-HEC). We showed that these cells were capable of generating erythrocytes ex vivo and we demonstrated that the formation of Ery-HEC was independent of the Runx1 gene expression. Using transcriptome analysis, we demonstrated that these cells coexpressed endothelial and erythroid genes such as Hbb-bh1 and Gata1 but we were surprised to detect the primitive erythroid genes Aqp3 and Aqp8 suggesting the formation of primitive erythrocytes at a much later time point than initially thought.Finally, we showed that enforced expression of Gata1 in endothelial cells was enough to initiate the erythroid transcriptional program.

Single-cell transcriptomics identifies CD44 as a new marker and regulator of haematopoietic stem cells development

“…Next, we decided to evaluate the impact of Runx1 loss of function on the different CD44 + cells. Using a Runx1 knockout mouse model 34 , we stained for VE-Cad, CD44 and Kit expression and performed transcriptional profiling on the sorted cells ( Fig. 7).…”

Single-cell atlas of major haematopoietic tissues sheds light on blood cell formation from embryonic endothelium

“…We stained YS derived from miR144/451 +/GFP mouse embryos. MiR144 and miR451 are micro RNAs specific of red blood cells, both primitive and definitive 44,45 . GFP marked erythroid cells and allowed us to visualise easily blood vessels in the YS.…”