Abstract 11412: Methyltransferase Smyd2 Mediate Atherosclerotic Plaque Calcification

Abstract

Introduction: Clinical manifestation of atherosclerosis is marked by calcification of vasculature, including the expression of mineralization regulating proteins (Sox9, Msx2, and Runx2) by vascular smooth muscle cells (VSMCs). This pathogenic remodeling of VSMCs into osteochondrogenic cell types is accompanied by increased proliferation, migration, and secretion of extracellular matrix proteins. This study aimed to determine the spatiotemporal role of SMYD2 in atherosclerotic plaque progression and calcification. Methods: SMC-specific SMYD2 knockout was generated in ApoE -/- mice (SMYD2 ΔSMC ApoE -/- ). Age and body weight-matched mice were fed with Western diet (WD) for 18 or 26 weeks. The distribution of atherosclerotic plaque was examined by En-face Oil-Red-O staining (ORO) of freshly collected aorta. Atherosclerotic plaque burden was determined by Hematoxylin & Eosin (H&E) staining. Collagen content and calcification of atherosclerotic plaque were determined by Masson's trichrome staining and von Kossa staining, respectively. The calcification-regulatory genes (MGP1, AGG and transcription factors SOX9, MSX2, BMP2, and RUNX2) in the aorta were analyzed by RT-qPCR. Results: SMC-specific deletion of SMYD2 protected mice from atherosclerotic plaque calcification. En-face ORO and H&E analysis of Brachiocephalic artery demonstrated a significant decrease in ORO positive area, total plaque size, and necrotic core area in SMYD2 ΔSMC ApoE -/- mice as compared to ApoE-/- mice, with no change in the distribution of collagen fibers. Von Kossa staining showed hydroxyapatite depots at the medial lining of the vasculature (microcalcification) in ApoE -/- mice fed with 18-week Western diet, while a smaller depot of macrocalcification was observed in SMYD2 ΔSMC ApoE -/- mice compared with ApoE -/- mice when fed with 26-week WD. mRNA analysis of key calcification transcription factors showed significant suppression of SOX9 and MSX2 genes in aortas of SMYD2 ΔSMC ApoE -/- mice compared with ApoE -/- mice, with downward trends of BMP2 and RUNX2 in both 18- or 26-week WD. Conclusion: SMYD2 ablation attenuates atherosclerotic plaque formation and calcification, suggests targeting SMYD2 can be a potential therapeutic strategy for atherosclerosis.