Abstract 239: Olfactomedin 2 Regulates Vascular Smooth Muscle Cell Phenotypic Modulation by Mediating the Interaction Between Runx2 and SRF

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Ning Shi ◽  
Xiao-Bing Cui ◽  
Shi-You Chen

Olfactomedin 2 (Olfm2) is a novel regulator for vascular smooth muscle cell (SMC) differentiation, but it is unclear whether Olfm2 is also involved in SMC phenotypic modulation, an important process associated with vascular injury. In this study, we found that Olfm2 was induced during PDGF-BB-induced SMC phenotypic modulation. Olfm2 knockdown attenuated PDGF-BB-induced suppression of SM marker genes including SM myosin heavy chain and SM22α, and also inhibited PDGF-BB-stimulated SMC proliferation and migration. On the other hand, Olfm2 overexpression down-regulated SM markers gene expression, and promoted SMC proliferation marker PCNA expression. Moreover, PDGF-BB slightly induced expression of Runx2, which interfered with the formation of SRF/myocardin ternary complex, but dramatically enhanced SRF-Runx2 interaction, suggesting that certain factors mediate SRF-Runx2 interaction. Indeed, Olfm2 physically interacted with both SRF and Runx2. Blockade of Olfm2 inhibited SRF association with Runx2, leading to increased association between SRF and myocardin, which in turn activated the transcription of SM markers, whereas overexpression of Olfm2 promoted SRF binding to Runx2. These results demonstrated that Olfm2 mediates the interaction between SRF and Runx2, contributing to SMC phenotypic modulation.

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Pan Li ◽  
Bing Yi ◽  
Qing Qin ◽  
Ming Chen ◽  
Xiaohua You ◽  
...  

Background Abnormal phenotypic switch of vascular smooth muscle cell (VSMC) is a hallmark of vascular disorders such as atherosclerosis and restenosis after angioplasty. Recently, microRNAs (miRNAs) emerge as critical regulators for vascular smooth muscle cell (VSMC) function. Our initial study identified miR-663 as one of the most sharply downregulated miRNAs in human proliferative aortic smooth muscle cells. Hypothesis MiR-663 is implicated in human VSMC phenotypic switch and the development of neointima formation. Methods and Results By using quantitative real-time PCR (qRT-PCR), we found that microRNA-663 (miR-663) was significantly downregulated in cultured human aortic VSMCs upon platelet-derived growth factor (PDGF) treatment, whereas its expression was markedly increased during VSMC differentiation as induced by either retinoid acid or SMC differentiation medium, a condition which induces SMC differentiation and inhibits cell proliferation. Furthermore, we demonstrated that overexpression of miR-663 significantly increased the expression of VSMC differentiation marker genes, such as SM22α, SM α-action, calponin, and SM myosin heavy chain, suggesting that miR-663 is a novel modulator implicated in human VSMC phenotypic switch. Moreover, miR-663 potently inhibited PDGF induced VSMC proliferation and migration. Mechanistically, we identified JunB as a downstream target of miR-663 in human VSMCs. Indeed, overexpression of miR-663 markedly inhibited the expression of the transcription factor JunB as well as its downstream molecules including matrix metallopeptidase-9 (MMP-9) and myosin light chain-9 (Myl9), thus inhibiting VSMC proliferation and migration. Finally, we showed that adeno-miR-663 markedly suppressed the neointimal lesion formation by approximately 50% in mice after vascular injury induced by carotid artery ligation, specifically via decreased JunB expression. Conclusion These results indicate that miR-663 is a novel modulator implicated in human VSMC phenotypic switch through targeting JunB expression and suggest that specific modulation of miR-663 in human VSMCs may represent a novel and attractive approach for the treatment of vascular proliferative diseases.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Yuming Li ◽  
Haitao Li ◽  
Xinfang Wang ◽  
Junya Wang ◽  
Zhongqiu Li

The current study was designed to explore the mechanisms of vascular smooth muscle cell (VSMC) proliferation and migration induced by adenosine diphosphate ribosyl cyclase(ADPRC). In this study, 32 Male ApoE-/- mice(6 weeks old, 18-22g)on a C57BL/6J background were divided into four groups, which received normal chow (n=8, NC group), high-fat Western-type diet (n=8, 0.25% cholesterol, 21% fat,HFD group), high-fat Western-type diet,infusion of 2,2′-dihydroxyazobenzene(DHAB, a ADPRC inhibitor, 2mg/kg/day, n=8, HFD-DHAB group) intraperitoneally or high-fat Western-type diet,infusion of LY294002(a Inhibitor of Akt, 5mg/kg/d, n=8, HFD-LY group) intraperitoneally, for 10 weeks. 8 male C57BL/6J mice served as control. After 10 weeks, mice were anesthetized with chloral hydrate, aorta was removed and immediately frozen in liquid nitrogen. Aortic atherosclerotic lesions, VSMC proliferation and migration were assessed by histomorphological observation, smooth muscle actin-α(α-SMA)and proliferating cell nuclear antigen (PCNA) examination. ADPRC expression and alterations of Akt, FOXO3a, phospho-FOXO3a and MMP-9 were determined by RT-PCR, Western Blot, Immunohistochemistry or Immunofluorescence. The results showed that, in aortic atherosclerotic lesions derived from atherosclerotic mice of HFD group, an increased VSMC proliferation and migration, reflected by the up-regulation of α-SMA and PCNA expression, were observed followed by increased expression of ADPRC, Akt, FOXO3a, phospho-FOXO3a and MMP-9. The enhanced expression of ADPRC and followed alterations of FOXO3a, phospho-FOXO3a, MMP-9 as well as α-SMA, PCNA, VSMC proliferation and migration were absent in NC group and C57BL/6J control mice. Treatment with DHAB or LY294002 reversed VSMC proliferation, migration and expression of Akt, FOXO3a, phospho-FOXO3a and MMP-9 in HFD-DHAB and HFD-LY group. These data shows that high-fat Western-type diet induced ADPRC may via PI3K-Akt to phosphorylate FOXO3a up-regulating MMP-9 to enhance vascular smooth muscle cell proliferation and migration in mice.


Author(s):  
Wenyan Li ◽  
Ping Deng ◽  
Junhua Wang ◽  
Zhaofeng Li ◽  
Huming Zhang

Abstract BACKGROUND MiR-17 is a small noncoding RNA that plays an important role in the development of tumorgenesis, which recently has emerged to be involved in regulation of inflammatory responses and angiogenesis. However, the effect and underlying mechanism of miR-17 on vascular smooth muscle cell (VSMC) phenotypic modulation have not been investigated. METHODS AND RESULTS In the current study, we observed that miR-17 expression tested by real-time polymerase chain reaction (RT-PCR) was downregulated in VSMCs administrated with platelet-derived growth factor-BB stimulation and carotid arteries subjected to wire injury, which were accompanied with decreased VSMC differentiation markers. Loss-of-function strategy demonstrated that miR-17 knockdown promoted VSMC phenotypic modulation characterized as decreased VSMC differentiation marker genes, increased proliferated and migrated capability of VSMC examined by RT-PCR and western blot analysis. Mechanistically, the bioinformatics analysis and luciferase assay demonstrated that miR-17 directly targeted Interferon Regulator Factor 9 (IRF9) and the upregulated IRF9 expression was responsible for the promoted effect miR-17 knockdown on VSMC phenotypic modulation. CONCLUSIONS Taken together, our results demonstrated that miR-17 knockdown accelerated VSMC phenotypic modulation partially through directly targeting to IRF9, which suggested that miR-17 may act as a novel therapeutic target for intimal hyperplasia management.


Author(s):  
Mei Li ◽  
Hongmei Zhu ◽  
Xiaoyan Hu ◽  
Fuhua Gao ◽  
Xinxin Hu ◽  
...  

Transmembrane protein 98 (TMEM98) is a novel gene. In a prior study, we have shown that siRNA-mediated knockdown of TMEM98 inhibited interleukin (IL)-8-promoted endothelial cell (EC) adhesion as well as vascular smooth muscle cell (VSMC) proliferation and migration in the vascular endothelial and smooth muscle cells dysfunction. Herein, we used gain- and loss-of-function approaches combined with biochemical techniques to further explore the role of TMEM98 in the vascular wall cell. The expression and secretion of TMEM98 was increased in cultured human umbilical vein endothelial cells (HUVECs) and VSMCs treated with IL-8 and platelet-derived growth factor (PDGF)-BB. Also, PDGF-BB secretion was increased in TMEM98-treated HUVECs and VSMCs. Thus, it appears that TMEM98 and PDGF-BB form a positive feedback loop in potentiation of EC adhesion as well as VSMC proliferation and migration. Knockdown of TMEM98 mediated by siRNA inhibited PDGF-BB-promoted EC adhesion by downregulating the expression of ICAM-1 and VCAM-1 as well as impaired the proliferation and migration of VSMCs through suppressing the AKT/GSK3β/cyclin D1 signaling pathway and reducing the expression of β-catenin. Hence, TMEM98 promoted EC adhesion through inducing the expression of ICAM-1/VCAM-1 and triggered VSMC proliferation and migration through activating the ERK and AKT/GSK3β signaling pathways. Taken together, TMEM98 may serve as a potential therapeutic target for the clinical treatment.


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