Expression data of the endothelial-to-hematopoietic transition in E8.5 concepti

During development a specialised subset of endothelial cells, the haemogenic endothelium, undergo an endothelial-to-haematopoietic transition. This process critically involves the transcription factor Runx1. Here we have isolated a specific subpopulation of endothelial cells using a Runx1 enhancer-reporter transgenic mouse line (23GFP). We have compared the gene expression profile of this population to non-23GFP expressing endothelial cells and CD41 expressing haematopoietic progenitor cells to assess whether 23GFP expression marks a biologically distinct subset of endothelium. We used affymetrix microarrays to detail the global programme of gene expression underlying the different populations and identified a distinct expression profile of the 23GFP expressing endothelium. 23GFP transgenic mouse embryos were dissected free of the ectoplacental cone at embryonic day E8.5, pooled, and sorted into 23GFP- and 23GFP+ endothelial (VE-Cad+ Ter119- CD45- CD41-) and CD41+ haematopoietic cells (VE-Cad+ Ter119-CD45-CD41+23GFP+) cells by FACS. Triplicate samples for each cell population were analysed. cDNA synthesis, fragmentation, and hybridisation were performed by the Stanford Protein and Nucleic Acid Facility.