Vitamin C dependent KDM6 demethylation specifies a functional chromatin state for endothelial-to-hematopoietic transition [ChIP-Seq]

Hematopoietic stem/progenitor cells (HSPCs) are generated from hemogenic endothelial cells (HECs) through endothelial-to-hematopoietic transition (EHT); however, the underlying mechanism remains poorly understood. Here, we report that HPC generation is significantly reduced in hPSC differentiatiation in a defined condition without vitamin C (Vc). Mechanistically, the endothelial cells generated in the absence of Vc fail to undergo EHT due to apparent failure in opening genomic loci essential for hematopoiesis. These loci exhibit abnormal accumulation of H3K27me3, a repressive histone modification due to lower activity of its demethylases. Consistently, deletion of H3K27me3 demethylases, JMJD3 and UTX, impaires HPC generation in the presence of Vc. Furthermore, Vc and jmjd3 are also important for HSC generation during zebrafish development. Together, we reveal an obligatory role of Vc underlying EHT process in hematopoisis and further support the important function of Vc during development. We compared the H3K4me3 and H3K27me3 binding of the GATA2/eGFP+ and GATA2/eGFP- endothelial cells by ChIP-Seq.