Abstract 17378: Atheroprotective Laminar Flow Represses the H3k27me3 Epigenetic Mark in Human Endothelial Cells Through Down-regulation of Ezh2
Introduction: Atherosclerosis is an epigenetic disease, in which pro-atherosclerotic factors, such as low-density lipoprotein (LDL), oxidized LDL, high glucose, disturbed flow (oscillatory shear stress), and homocysteine impacts DNA methylation and histone modifications on specific gene loci in vascular cells. However, it remains largely unknown whether atheroprotective laminar flow regulates endothelial function by modifying histone methylation. Enhancer of zeste homolog 2 (EZH2) is a histone-lysine N-methyltransferase enzyme and the catalytic subunit of the polycomb repressive complex 2 (PRC2), which methylates lysine-27 (H3K27me) of histone H3, leading to transcriptional repression of the affected target gene.
Hypothesis: Laminar flow affects EZH2 mediated histone methylation and downregulation of EZH2/H3K27me3 mediates the atheroprotective effects of laminar flow.
Methods: Western blot, real time PCR, en face staining, ChIP aasay, RNA-sequencing.
Results: Here we report that laminar flow decreases the H3K27me3 epigenetic mark in human endothelial cells (ECs) through down-regulation of EZH2, which in part mediates laminar flow atheroprotective action. In vivo, EZH2 expression and activity (H3K27me3) was significantly diminished in laminar flow area of mouse aorta. In vitro, EZH2 expression and activity (H3K27me3) was reduced in cultured human ECs subjected to laminar flow . Moreover, laminar flow decreased expression of EZH2 via flow-responsive miR101. RNA sequencing (RNA-Seq) profiling in EZH2-depleted ECs reveals that EZH2 regulates a cohort of genes relevant to vascular inflammation. Like laminar flow, siRNA-mediated EZH2 depletion or pharmacological inhibition of EZH2 activity reduced TNF-α induced monocyte adhesion to human ECs.
Conclusions: Collectively, our results demonstrate that laminar flow modulates the EZH2/H3K27me3 pathway in ECs. Our findings also suggest that EZH2 critically regulates the inflammatory status in endothelium and pharmacological inhibition of EZH2 may therefore be a promising strategy for treating atherosclerotic vascular disease.
Author Disclosures: S. Xu: None. M. Yin: None. Y. Xu: None. M. Koroleva: None. Z. Jin: None.
- © 2016 by American Heart Association, Inc.