Swiers, GemmaBaumann, ClaudiaO'Rourke, JohnGiannoulatou, EleniTaylor, StephenJoshi, AnaghaMoignard, VictoriaPina, CristinaBee, ThomasKokkaliaris, Konstantinos D.Yoshimoto, MomokoYoder, Mervin C.Frampton, JonSchroeder, TimmEnver, TariqGöttgens, Bertholdde Bruijn, Marella F. T. R.2016-03-142016-03-142013Swiers, G., Baumann, C., O’Rourke, J., Giannoulatou, E., Taylor, S., Joshi, A., … de Bruijn, M. F. T. R. (2013). Early dynamic fate changes in haemogenic endothelium characterized at the single-cell level. Nature Communications, 4, 2924. http://doi.org/10.1038/ncomms39242041-1723https://hdl.handle.net/1805/8848Haematopoietic stem cells (HSCs) are the founding cells of the adult haematopoietic system, born during ontogeny from a specialized subset of endothelium, the haemogenic endothelium (HE) via an endothelial-to-haematopoietic transition (EHT). Although recently imaged in real time, the underlying mechanism of EHT is still poorly understood. We have generated a Runx1 + 23 enhancer-reporter transgenic mouse (23GFP) for the prospective isolation of HE throughout embryonic development. Here we perform functional analysis of over 1,800 and transcriptional analysis of 268 single 23GFP+ HE cells to explore the onset of EHT at the single-cell level. We show that initiation of the haematopoietic programme occurs in cells still embedded in the endothelial layer, and is accompanied by a previously unrecognized early loss of endothelial potential before HSCs emerge. Our data therefore provide important insights on the timeline of early haematopoietic commitment.en-USPublisher PolicyEmbryo, MammaliancytologyGene Expression Regulation, DevelopmentalHemangioblastsphysiologySingle-Cell AnalysismethodsArticle