Abstract 16720: Disturbed Flow Upregulates Dnmt1 Expression in Endothelial Cells, Which Induces Genome-Wide DNA Methylation Pattern Changes and Atherosclerosis in Mice
Atherosclerosis, an inflammatory disease of the arterial walls, preferentially occurs in regions of disturbed blood flow (DF). DF alters gene expression and induces endothelial cell (EC) dysfunction and atherosclerosis in the presence of additional risk factors such as hypercholesterolemia. Epigenetics controls aberrant gene expression in many diseases, but the mechanism of flow-induced epigenetic gene regulation via DNA methylation has not been well studied. Previously, we identified ~600 flow-responsive EC genes by a gene transcript microarray study using the mouse carotid artery partial ligation model. Further analysis revealed that DF upregulates mRNA and protein expression of DNA methyltransferase 1 (DNMT1), a key enzyme that methylates DNA site-specifically in ECs in vivo (mouse aortas) and in vitro (cultured ECs exposed to oscillatory shear stress as compared to unidirectional laminar shear stress). We found that DNMT1 inhibition by the specific DNMT1 inhibitor 5-Aza-2’deoxycytidine (5Aza) leads to a remarkable reduction in EC inflammation induced by oscillatory shear in vitro and atherosclerotic plaque formation in ApoE-/- mice on high-fat diet. To determine the underlying mechanisms of the 5Aza effect, we performed an in vivo genome-scale methylation analysis by Reduced Representation Bisulfite Sequencing (RRBS) using EC-enriched DNA from the partially ligated left common carotid artery (LCA) and the contralateral control (RCA) of C57 mice treated with or without 5Aza. Our RRBS study demonstrated that one week of DF exposure in the LCA caused significant promoter hypermethylation that could be prevented by 5Aza treatment in 119 genes by more than 35%. Of these, 21 genes also displayed significantly suppressed transcript expression in DF. Examples of genes with DF-inducible and 5Aza-inhibitable hypermethylation include members of the Hox/miR10 family. These results suggest that DNMT1 is a flow-sensitive gene that induces aberrant DNA methylation patterns in the arterial wall and subsequently leads to atherosclerosis. DNMT1 may be a novel therapeutic target of atherosclerosis.
- © 2013 by American Heart Association, Inc.