Global DNA methylation and extracellular matrix remodeling in aortic smooth muscle versus endothelial cells in hyperhomocysteinemia (1120.5)

Abstract

Introduction: Homocysteine (Hcy) is a byproduct of DNA methylation. Increased levels of Hcy (HHcy) have been shown to induce smooth muscle cell (SMC) proliferation and inhibit endothelial cell proliferation. It is well known that HHcy causes increased activation of matrix metalloproteinases, a key factor in vascular remodeling. However, the role of global DNA methylation in regulating aortic matrix remodeling is not known.Hypothesis: In the present study, we hypothesize that global DNA methylation during HHcy regulates the expression of MMPs in mouse aortic SMCs and endothelial cells (MAEC).Methods: Mouse SMC and MAEC were cultured with 80µM Hcy and 100µM Aza deoxycytidine (AzadC), DNA methyltransferase inhibitor.Results: Global DNA methylation analysis by ELISA showed that in HHcy, there was a 2 fold and 1.3 fold increase in %5‐mC in SMC and MAECs respectively. During HHcy, there was an increased expression and activity of MMP9 in SMCs, which depreciated after AzadC treatment. Methylation Specific PCR (MS‐PCR) showed increased methylation status of Hcy metabolism genes, CBS and MTHFR in SMCs and MAECs.Summary: Our results suggest that HHcy causes a greater global hyper‐methylation in aortic SMC than in MAEC. This may suggest that Hcy generated through methylation contributes to vascular remodeling.Grant Funding Source: NIH