GSE112336
Differential epigenetic profiling of human aortic endothelial cells (HAEC) in response to shear stress forces using ChIP-Seq of H3K27ac
Biomechanical cues dynamically control major cellular processes but whether genetic variants actively participate in the mechano-sensing mechanisms remain unexplored. Vascular homeostasis is tightly regulated by hemodynamic forces. Exposure to disturbed blood flow at arterial sites of branching and bifurcation causes constant activation of vascular endothelium contributing to the development of atherosclerosis, the major cause of coronary artery disease (CAD). Conversely, unidirectional flow promotes the anti-inflammatory and anti-permeable endothelial phenotype resistant to atherogenesis. Genome-wide association studies (GWAS) have identified chromosome 1p32.2 as one of the loci most strongly associated with CAD susceptibility; however, the causal mechanism related to this CAD locus remain unknown. PhosphoLipid PhosPhatase 3 (PLPP3) is located at 1p32.2 and encodes a phosphatase that suppresses endothelial inflammation and promotes monolayer integrity by hydrolyzing lysophosphatidic acid. Our previous studies demonstrated that PLPP3 is significantly reduced in vascular endothelium exposed to disturbed flow while unidirectional flow significantly increases endothelial PLPP3 expression in vitro and in vivo. In addition, CAD protective allele at 1p32.2 locus is associated with increased PLPP3 in an endothelium-specific manner, shown by expression quantitative trait locus (eQTL). Using Assay for Transposase-Accessible Chromatin using Sequencing (ATAC-Seq), H3K27ac ChIP-Seq, H3K4me2 ChIP-Seq, and luciferase assays, here we identified a mechano-sensitive endothelial enhancer in PLPP3 intron 5 that is dynamically activated by unidirectional flow. Deletion of this enhancer by CRISPR/Cas9-based genome editing causatively reduces endothelial PLPP3 expression and promotes endothelial activation, and moreover, impairs endothelial PLPP3 induction by unidirectional flow. Chromatin accessibility quantitative trait locus (caQTL) mapping, allelic imbalance assay, and luciferase assays further demonstrated that CAD protective allele at rs17114036 in the PLPP3 intron 5 confers an increased enhancer activity. ChIP-PCR and luciferase assays showed that CAD protective allele C at rs17114036 creates a binding site (CACC) for mechano-sensitive transcription factor KLF2, leading to increased enhancer activity under unidirectional flow. These results elucidate the contributory role of CAD genetic predisposition in critical endothelial mechano-transduction mechanisms and suggest that human genetic variants provide a previously unappreciated layer of regulatory control in cellular mechano-sensing mechanisms. Overall design: 20 samples. In five independent experiments HAEC were subjected to unidirectional and disturbed flow and ChIP was performed for H3K27ac. Inputs for each sample are included to control for background.