Silencing METTL3 Stabilizes Atherosclerotic Plaques by Regulating the Phenotypic Transformation of Vascular Smooth Muscle Cells via the miR-375-3p/PDK1 Axis.

PURPOSE: Atherosclerosis (AS) is a primary cause of cardiovascular diseases. This study investigated the mechanism of methyltransferase-like 3 (METTL3) in AS plaques via modulating the phenotypic transformation of vascular smooth muscle cells (VSMCs). METHODS: AS mouse models and MOVAS cell models were established through high-fat diet and the treatment of ox-LDL, respectively. METTL3 expression in AS models was detected via RT-qPCR and Western blot. The AS plaques, lipid deposition, and collagen fibers were examined via histological staining. The levels of Ly-6c, α-SMA, and OPN were examined via Western blot. The blood lipid indexes in mouse aortic tissues were determined using kits. The proliferation and migration of MOVAS cells were detected via CCK-8 and Transwell assays. The m6A modification level of mRNA was quantified. The binding relationship between pri-miR-375 and DGCR8, and the enrichment of m6A on pri-miR-375 were detected via RIP. The binding relationship between miR-375-3p and 3-phosphoinositide-dependent protein kinase-1 (PDK1) was verified via dual-luciferase assay. Joint experiments were designed to investigate the role of miR-375-3P/PDK1 in the phenotypic transformation of VSMCs. RESULTS: METTL3 was highly expressed in AS. Silencing METTL3 alleviated AS progression and stabilized AS plaques in mice, and limited the phenotypic transformation of VSMCs induced by ox-LDL. Silencing METTL3 inhibited m6A level and decreased the binding of DGCR8 to pri-miR-375 and further limited miR-375-3p expression. miR-375-3p targeted PDK1 transcription. miR-375-3p upregulation or PDK1 downregulation facilitated the phenotypic transformation of VSMCs. CONCLUSION: METTL3-mediated m6A modification promoted VSMC phenotype transformation and made AS plaques more vulnerable via the miR-375-3p/PDK1 axis.

lncRNA­SNHG7­003 inhibits the proliferation, migration and invasion of vascular smooth muscle cells by targeting the miR­1306­5p/SIRT7 signaling pathway.

Long non­coding RNAs (lncRNAs) have been discovered to participate in the progression of various types of disease and may be a promising biomarker for atherosclerosis (AS). The present study aimed to investigate the regulatory mechanisms of the lncRNA, small nucleolar RNA host gene 7­003 (SNHG7­003), on the proliferation, migration and invasion of vascular smooth muscle cells (VSMCs). VSMCs were first stimulated with oxidized low­density lipoprotein (ox­LDL) to simulate AS in a high fat environment. The expression levels of SNHG7­003, microRNA (miRNA/miR)­1306­5p and sirtuin 7 (SIRT7) were analyzed by reverse transcription­quantitative PCR and the effects of each of these factors on VSMC proliferation, migration and invasion were determined by Cell Counting Kit­8, wound healing and Transwell assays, respectively. Western blot analysis was also used to analyze the protein expression levels of α­smooth muscle actin (α­SMA), matrix metalloproteinase (MMP)2 and MMP9. The interactions between SNHG7­003 or SIRT7 and miR­1306­5p were determined using dual­luciferase reporter assays. The results revealed that the SNHG7­003 expression levels were downregulated in VSMCs exposed to ox­LDL, while the overexpression (OE) of SNHG7­003 significantly inhibited the proliferation, migration and invasion of VSMCs induced by ox­LDL. Transfection with miR­1306­5p mimic abrogated the effects of the inhibitory effects induced by SNHG7­003 OE. SIRT7 was validated to be a target gene of miR­1306­5p, exhibiting similar inhibitory effects as SNHG7­003 in AS. It was also discovered to be involved in the regulatory effects of the SNHG7­003/miR­1306­5p axis in VSMCs. On the whole, the findings of the present study indicate that SNHG7­003 may inhibit the proliferation, migration and invasion of VSMCs via the miR­1306­5p/SIRT7 signaling pathway. These findings may provide a novel basis for the development of treatment strategies for AS.

The neurokinin-1 receptor antagonist aprepitant ameliorates oxidized LDL-induced endothelial dysfunction via KLF2.

Atherosclerosis is the main cause of many cardiovascular diseases. Endothelial dysfunction is recognized as an early event in the development of atherosclerosis. Many drugs have been studied to mitigate hyperlipidemia-induced endothelial injury. Studies have demonstrated that neuropeptide substance P (SP) and its preferred receptor neurokinin receptor 1 (NK-1R) are involved in the pathological progression of cardiovascular disease. In this study, we show that aprepitant, a selective NK-1R antagonist, possesses beneficial effects that protect endothelial cells from oxidized low-density lipoprotein (ox-LDL)-induced inflammatory response and injury. Our data demonstrate that NK-1R is expressed in both aortic and vein-originated endothelial cells and that ox-LDL treatment induces NK-1R expression. Treatment with aprepitant suppresses induction of endothelial vascular adhesion molecule (VCAM-1 and E-selectin) and cytokine by ox-LDL. The presence of aprepitant mitigates adhesion of monocytes to endothelial cells and the reduction in eNOS/NO triggered by ox-LDL. Mechanistically, we demonstrate that aprepitant suppresses ERK5-KLF2 axis activation. Silencing of KLF2 abolishes the inhibitory role of aprepitant on ox-LDL-induced inflammatory response, suggesting that its action is dependent on KLF2. Collectively, our data support that aprepitant exerts an anti-inflammatory effect. Further research is required to investigate the therapeutic potential of aprepitant in vascular inflammation resulting from atherosclerosis.

SIRT7 Regulates the Vascular Smooth Muscle Cells Proliferation and Migration via Wnt/ß-Catenin Signaling Pathway.

A huge amount of evidence indicates that sirtuin 7 (SIRT7), a key mediator of many cellular activities, plays a crucial role in the pathogenesis of various diseases. However, little is known about the role of SIRT7 in atherosclerosis. This study investigated the potential role of SIRT7 in regulating the proliferation and migration of human vascular smooth muscle cells (HAVSMCs) and its possible molecular mechanism. In this study, human vascular smooth muscle cells (HAVSMCs) were induced by oxidized low-density lipoprotein (ox-LDL) to establish atherosclerosis (AS) cell model. Immunofluorescence staining and Western blot were used to detect the level of α-SMA expression, which was a marker protein in AS. In addition, RT-qPCR and Western blot assay were applied for exploring the mRNA and protein expression levels of SIRT7, Wnt, ß-catenin, and cyclin D1 after knockdown or overexpression of SIRT7. And, furthermore, Cell Counting Kit-8 assay, flow cytometry, and wound-healing assay were used to assess HAVSMCs proliferation, cell cycle, and migration. Dickkopf-1 (DKK-1), a secretory glycoprotein that can block Wnt/ß-catenin pathway, was used in SIRT7 overexpression HAVSMCs; subsequently cells proliferation and migration were assessed by Cell Counting Kit-8 assay, flow cytometry analysis, and wound-healing assay. We found that knockdown of SIRT7 significantly promoted cell proliferation and migration, decreased the percentages of cells in the G1 and G2 phases, and increased those in the S phase and downregulated the protein expression levels of Wnt, ß-catenin, and cyclin D1, while overexpression of SIRT7 had reverse results. After treatment with Wnt/beta-catenin pathway inhibitor DKK-1 in SIRT7 overexpression HAVSMCs, cell proliferation and migration were increased, respectively. In conclusion, SIRT7 inhibited HAVSMCs proliferation and migration via enhancing Wnt/ß-catenin activation, which provided a novel therapeutic strategy for antiatherosclerosis.