Endothelial cells (ECs) are central determinants of vascular health. Dysfunction of ECs, characterized in part by reduced nitric oxide (NO) signaling, contributes to various cardiovascular diseases worldwide. Multiple lines of evidence support an essential role for KLF2 and KLF4 in endothelial cell biology. However, the precise in vivo role of both factors in orchestrating EC health and vascular hemostasis remains undetermined. The central hypotheses of this work are (i) KLF2 and KLF4 serve as vital transcriptional regulators that maintain endothelial health and vascular hemostasis in adult animal, and (ii) these factors govern endothelial hemoglobin subunit alpha (HBA) expression, which is critical to fine-tune NO diffusion from EC to vascular smooth muscle cells (SMC). In vivo studies using inducible-genetic deficiency of both endothelial KLF2 and KLF4 (double knockout; EC-DKO) in adult mice caused acute deterioration of vascular permeability and disruption of coagulation system, leading to heart failure, stroke, and death within days upon gene deletion. Mechanistically, abrogation of both KLF2 and KLF4 profoundly altered EC transcriptome, suggesting that these factors mediate a broad range of endothelial genes and thus determine EC homeostasis. Further, KLF2 and KLF4 transcriptionally regulated HBA gene expression in ECs. Collectively, this study identifies KLF2 and KLF4 as essential determinants of endothelial health and vascular homeostasis.
