ABSTRACT
Coronary restenosis is an important cause of poor long-term prognosis in patients with coronary heart disease. Here, we show that lysine methyltransferase SMYD2 expression in the nucleus is significantly elevated in serum- and PDGF-BB-induced vascular smooth muscle cells (VSMCs), and in tissues of carotid artery injury-induced neointimal hyperplasia. Smyd2 overexpression in VSMCs (Smyd2-vTg) facilitates, but treatment with its specific inhibitor LLY-507 or SMYD2 knockdown significantly inhibits VSMC phenotypic switching and carotid artery injury-induced neointima formation in mice. Transcriptome sequencing revealed that SMYD2 knockdown represses the expression of serum response factor (SRF) target genes and that SRF overexpression largely reverses the inhibitory effect of SMYD2 knockdown on VSMC proliferation. HDAC3 directly interacts with and deacetylates SRF, which enhances SRF transcriptional activity in VSMCs. Moreover, SMYD2 promotes HDAC3 expression via tri-methylation of H3K36 at its promoter. RGFP966, a specific inhibitor of HDAC3, not only counteracts the pro-proliferation effect of SMYD2 overexpression on VSMCs, but also inhibits carotid artery injury-induced neointima formation in mice. HDAC3 partially abolishes the inhibitory effect of SMYD2 knockdown on VSMC proliferation in a deacetylase activity-dependent manner. Our results reveal that the SMYD2-HDAC3-SRF axis constitutes a novel and critical epigenetic mechanism that regulates VSMC phenotypic switching and neointimal hyperplasia.
ABSTRACT
<p><b>OBJECTIVE</b>This study was aimed to investigate the effects of carbon monoxide releasing molecule (CORM-2), a novel carbon monoxide carrier, on the reendothelialization of carotid artery in rat endothelial denudation model.</p><p><b>METHODS</b>Male rats subjected to carotid artery balloon injury were treated with CORM-2, inactive CORM-2 (iCORM-2) or dimethyl sulfoxide (DMSO). The reendothelialization capacity was evaluated by Evans Blue dye and the immunostaining with anti-CD31 antibody. The number of circulating endothelial progenitor cells (EPCs) was detected by flow cytometry. The proliferation, migration, and adhesion of human umbilical vein endothelial cells (HUVECs) were assessed by using [3H]thymidine, Boyden chamber and human fibronectin respectively. The expressions of protein were detected by using western blot analysis.</p><p><b>RESULTS</b>CORM-2 remarkably accelerated the re-endothelialization 5 d later and inhibited neointima formation 28 d later. In addition, the number of peripheral EPCs significantly increased in CORM-2-treated rats than that in iCORM-2 or DMSO-treated rats after 5 d later. In vitro experiments, CORM-2 significantly enhanced the proliferation, migration and adhesion of HUVECs. The levels of Akt, eNOS phosphorylation, and NO generation in HUVECs were also much higher in CORM-2 treated group. Blocking of PI3K/Akt/eNOS signaling pathway markedly suppressed the enhanced migration and adhesion of HUVECs induced by CORM-2.</p><p><b>CONCLUSION</b>CORM-2 could promote endothelial repair, and inhibit neointima formation after carotid artery balloon injury, which might be associated with the function changes of HUVECs regulated by PI3K/Akt/eNOS pathway.</p>
Subject(s)
Animals , Humans , Male , Rats , Carbon Monoxide , Metabolism , Pharmacology , Carotid Artery Injuries , Drug Therapy , Allergy and Immunology , Metabolism , Pathology , Carotid Artery, Common , Allergy and Immunology , Metabolism , Pathology , Cell Adhesion , Disease Models, Animal , Endothelial Cells , Allergy and Immunology , Metabolism , Pathology , Endothelium, Vascular , Metabolism , Pathology , Rats, Sprague-DawleyABSTRACT
Background Neointima formation plays an important role in the pathogenesis of atherosclerosis and restenosis after angioplasty.We hypothesized if atorvastatin inhibits neointima formation mediating decreases in cathepsin S (Cat S) and nuclear factor-?B(NF-?B) expression.Objective The study was aimed to explore the effect of atorvastatin on the neointima formation,Cat S and NF-?B expression in rats after balloon-injured carotid artery.Methods Twenty-four male Sprague-Dawley rats were randomly one of three arms:control group(n=8),surgery group(n=8) and atorvastatin group[10 mg/(kg?d),n=8] for 4 weeks.Surgery and atorvastatin group were performed with balloon angioplasty to the left common carotid artery.The serum levels of IL-1? were measured using enzyme-link-immunosorbent assay(ELISA).Carotid arteries were excised and examined with pathomorphology.The expression of Cat S and NF-?B was measured using using the RT-PCR and immunohistochemistry techniques.Results Compared with surgery group,atorvastatin decreased intima area and intima media ratio(I/M)[intima area:(148.6?8.8)?103 vs (64.8?5.1)?103 ?m2;I/M:(2.1?0.2) vs (0.9?0.1),all P