KLF4 Recruits SWI/SNF to Increase Chromatin Accessibility and Reprogram the Endothelial Enhancer Landscape under Laminar Shear Stress [ChIP-seq BRG1]

Physiologic laminar shear stress (LSS) induces an endothelial gene expression profile that is vasculo-protective. In this report, we delineate how LSS mediates changes in the epigenetic landscape to promote this beneficial response. We show that under LSS, KLF4 interacts with the SWI/SNF nucleosome remodeling complex to increase accessibility at enhancer sites that promote expression of homeostatic endothelial genes. By combining molecular and computational approaches we discovered enhancers that loop to promoters of known and novel KLF4- and LSS-responsive genes that stabilize endothelial cells and suppress inflammation, such as BMPR2 and DUSP5. By linking enhancers to genes that they regulate under physiologic LSS, our work establishes a foundation for interpreting how non-coding DNA variants in these regions might disrupt protective gene expression to influence vascular disease. For KLF gain-of-function, pulmonary artery endothelial cells (PAEC) were transduced with adenoviral vectors encoding a constitutively active mutant of MEK5, or GFP as control, (n=2 experimental replicates), 90h post-transduction, cells were fixed and prepared for ChIP-Seq for H3K4me1, H3K27ac, KLF4 and BRG1.