GSE160647
Epigenetic Landscape Reveals MECOM As An Endothelial Lineage Regulator
Background: A comprehensive understanding of the determinants of endothelial cell (EC) lineage specification will advance strategies for cardiovascular regenerative medicine. Recent studies found that unique epigenetic signatures specifically regulate cell identity genes, making it possible to systematically identify novel EC master regulators by leveraging extensive epigenomic datasets available for EC. Methods: We developed a method to identify novel regulators of endothelial cell identity by integrating multiple epigenetic patterns. We verified MEOCM as a master EC lineage regulator using both in vivo and in vitro experiments. The mechanism of action of MECOM as EC lineage regulator was characterized by integrative analysis of Hi-C, DNase-Seq, ChIP-Seq, scRNA-seq and bulk RNA-Seq data, as well as extensive molecular, cellular, and animal experiments. Results: We identified MECOM to be the leading candidate as an EC lineage regulator. Single-cell RNA-Seq analysis further revealed that MECOM-positive cells are exclusively enriched in the cell cluster of bona fide iPSC-ECs. We verified that MECOM was required for human endothelial differentiation, EC functions, and Zebrafish angiogenesis. Through integrative analysis of Hi-C, DNase-Seq, ChIP-Seq, and RNA-Seq data, we find MECOM binds enhancers that form chromatin loops to regulate EC identity genes. Specifically, we identified the VEGF signaling pathway to be a key downstream target of MECOM. Conclusions: Our work provides new insights into epigenetic regulation of cell identity genes and uncovered MECOM as a master regulator of EC identity. Overall design: RNA-Seq data of Control and MECOM KO (CRISPR-gRNA KO pools),  HUVECs