Aberrant promoter methylation of multiple genes in VSMC proliferation induced by Hcy

Abstract

Vascular smooth muscle cell (VSMC) proliferation is a primary pathological event in atherosclerosis (AS), and homocysteine (Hcy) is an independent risk factor for AS. However, the underlying mechanisms are still lagging. Studies have used the combination of methylation of promoters of multiple genes to diagnose tumors, thus the aim of the current study was to investigate the role of methylation status of several genes in VSMCs treated with Hcy. CpG islands were identified in the promoters of platelet‑derived growth factor (PDGF), p53, phosphatase and tensin homologue on chromosome 10 (PTEN) and mitofusin 2 (MFN2). Hypomethylation was observed to occur in the promoter region of PDGF, hypermethylation in p53, PTEN and MFN2, and hypomethylation in two global methylation indicators, aluminium (Alu) and long interspersed nucleotide element‑1 (Line‑1). This was accompanied by an increase in the expression of PDGF, and reductions of p53, PTEN and MFN2, both in mRNA and protein levels. An elevation of S‑adenosylmethionine (SAM) and a reduction of S‑adenosylhomocysteine (SAH) and the SAM/SAH ratio were also identified. In conclusion, Hcy impacted methylation the of AS‑associated genes and global methylation status that mediate the cell proliferation, which may be a character of VSMCs treated with Hcy. The data provided evidence for mechanisms of VSMCs proliferation in AS induced by Hcy and may provide a new perspective for AS induced by Hcy.

Mechanism of extracellular‑superoxide dismutase DNA methylation in a hyperhomocysteinemia‑induced atherosclerosis in a mouse model

“…Rhee et al (36) revealed that a marked reduction in the number of methylated CpG dinucleotides in the EC-SOD gene were detected in AS aortas compared with normal aortic intima-media. A number of previous studies have reported that Hcy is regulated by the expression of DNMTs, particularly DNMT1 (13,37). In the process of methyl transfer reactions, methionine is converted to Hcy with SAM and SAH as byproducts.…”

“…However, to the best of our knowledge there is no direct evidence explaining the mechanisms by which Hcy affects the expression of EC-SOD and disturbs the balance between oxidative-induced AS. Epidemiological studies have demonstrated that a mildly elevated plasma Hcy level is an independent risk factor for the development of AS (13). Hcy is a non-protein, sulfur-containing amino acid, which is formed exclusively by the demethylation of methionine (14).…”

Homocysteine-induced proliferation of vascular smooth muscle cells occurs via PTEN hypermethylation and is mitigated by Resveratrol

“…The thermal cycler (Funglyn Biotech, Inc., Toronto, ON, Canada) conditions comprised an initial activation step at 95˚C for 5 min, followed by a 2-step PCR program of 95˚C for 15 sec, annealing temperatures for 15 sec and at 72˚C for 30 sec for 30 cycles. Subsequently, the relative alterations in the mRNA expression levels of DNMT1 and PTEN were determined by fold-change analysis, in which the degree of change was calculated as 2 -∆∆Cq , where Cq=(Cq gene -Cq GAPDH ) treatment-(Cq gene -Cq GAPDH ) control (17).…”

“…The transfection efficiency was determined by detecting the fluorescence intensity via an inverted fluorescence phase contrast microscope (Olympus IX71, Olympus Corporation, Tokyo, Japan). The transfected VSMCs were treated with Hcy for 24 h and mRNA expression of PTEN/DNMT1 was detected with RT-qPCR (17). Western blotting was carried out to examine the protein expression of PTEN/DNMT1 (17).…”

“…The transfected VSMCs were treated with Hcy for 24 h and mRNA expression of PTEN/DNMT1 was detected with RT-qPCR (17). Western blotting was carried out to examine the protein expression of PTEN/DNMT1 (17).…”