scholarly journals Interleukin-1β modulates smooth muscle cell phenotype to a distinct inflammatory state relative to PDGF-DD via NF-κB-dependent mechanisms

2012 ◽  
Vol 44 (7) ◽  
pp. 417-429 ◽  
Author(s):  
Matthew R. Alexander ◽  
Meera Murgai ◽  
Christopher W. Moehle ◽  
Gary K. Owens

Smooth muscle cell (SMC) phenotypic modulation in atherosclerosis and in response to PDGF in vitro involves repression of differentiation marker genes and increases in SMC proliferation, migration, and matrix synthesis. However, SMCs within atherosclerotic plaques can also express a number of proinflammatory genes, and in cultured SMCs the inflammatory cytokine IL-1β represses SMC marker gene expression and induces inflammatory gene expression. Studies herein tested the hypothesis that IL-1β modulates SMC phenotype to a distinct inflammatory state relative to PDGF-DD. Genome-wide gene expression analysis of IL-1β- or PDGF-DD-treated SMCs revealed that although both stimuli repressed SMC differentiation marker gene expression, IL-1β distinctly induced expression of proinflammatory genes, while PDGF-DD primarily induced genes involved in cell proliferation. Promoters of inflammatory genes distinctly induced by IL-1β exhibited over-representation of NF-κB binding sites, and NF-κB inhibition in SMCs reduced IL-1β-induced upregulation of proinflammatory genes as well as repression of SMC differentiation marker genes. Interestingly, PDGF-DD-induced SMC marker gene repression was not NF-κB dependent. Finally, immunofluorescent staining of mouse atherosclerotic lesions revealed the presence of cells positive for the marker of an IL-1β-stimulated inflammatory SMC, chemokine (C-C motif) ligand 20 (CCL20), but not the PDGF-DD-induced gene, regulator of G protein signaling 17 (RGS17). Results demonstrate that IL-1β- but not PDGF-DD-induced phenotypic modulation of SMC is characterized by NF-κB-dependent activation of proinflammatory genes, suggesting the existence of a distinct inflammatory SMC phenotype. In addition, studies provide evidence for the possible utility of CCL20 and RGS17 as markers of inflammatory and proliferative state SMCs within atherosclerotic plaques in vivo.

2006 ◽  
Vol 26 (24) ◽  
pp. 9456-9470 ◽  
Author(s):  
Ken'ichiro Hayashi ◽  
Seiji Nakamura ◽  
Wataru Nishida ◽  
Kenji Sobue

ABSTRACT During the onset and progression of atherosclerosis, the vascular smooth muscle cell (VSMC) phenotype changes from differentiated to dedifferentiated, and in some cases, this change is accompanied by osteogenic transition, resulting in vascular calcification. One characteristic of dedifferentiated VSMCs is the down-regulation of smooth muscle cell (SMC) marker gene expression. Bone morphogenetic proteins (BMPs), which are involved in the induction of osteogenic gene expression, are detected in calcified vasculature. In this study, we found that the BMP2-, BMP4-, and BMP6-induced expression of Msx transcription factors (Msx1 and Msx2) preceded the down-regulation of SMC marker expression in cultured differentiated VSMCs. Either Msx1 or Msx2 markedly reduced the myocardin-dependent promoter activities of SMC marker genes (SM22α and caldesmon). We further investigated interactions between Msx1 and myocardin/serum response factor (SRF)/CArG-box motif (cis element for SRF) using coimmunoprecipitation, gel-shift, and chromatin immunoprecipitation assays. Our results showed that Msx1 or Msx2 formed a ternary complex with SRF and myocardin and inhibited the binding of SRF or SRF/myocardin to the CArG-box motif, resulting in inhibition of their transcription.


2000 ◽  
Vol 276 (1) ◽  
pp. 341-347 ◽  
Author(s):  
Christopher P. Mack ◽  
Avril V. Somlyo ◽  
Martina Hautmann ◽  
Andrew P. Somlyo ◽  
Gary K. Owens

2009 ◽  
Vol 296 (4) ◽  
pp. H1027-H1037 ◽  
Author(s):  
Rebecca A. Deaton ◽  
Qiong Gan ◽  
Gary K. Owens

There is clear evidence that the phenotypic modulation of smooth muscle cells (SMCs) contributes to the pathophysiology of vascular disease. Phenotypic modulation refers to the unique ability of SMCs to alter their phenotype in response to extracellular stimuli and is hallmarked by the loss of SMC marker gene expression. The transcription factor Krüppel-like factor 4 (KLF4) is a known powerful negative regulator of SMC marker gene expression that works, in part, by decreasing the expression of the serum response factor (SRF) myocardin. KLF4 is not expressed in healthy adult SMCs but is increased in SMCs in response to vascular injury in vivo or PDGF-BB treatment in vitro. The aim of the present study was to determine the molecular mechanisms that regulate the expression of KLF4 in phenotypically modulated SMCs. The results demonstrated that the transcription factor stimulating protein-1 (Sp1) regulated the expression of KLF4 in SMCs. The KLF4 promoter contains three consensus Sp1 binding sites. Using a series of truncated KLF4 promoters, we showed that only fragments containing these Sp1 sites could be activated by PDGF-BB. In addition, overexpression of Sp1 alone was sufficient to increase the activity of the KLF4 promoter. Moreover, inhibiting Sp1 expression with small-interfering RNA attenuated the effects of PDGF-BB on KLF4 expression. Mutation of the three Sp1 sites within the KLF4 promoter abolished both baseline and PDGF-BB-induced activity. Finally, the results demonstrated enhanced Sp1 binding to the KLF4 promoter in SMCs treated with PDGF-BB in vitro and following vascular injury in vivo. Taken together, the results suggest a novel role for Sp1 in increasing the expression of KLF4 in phenotypically modulated SMCs.


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.


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.


2009 ◽  
Vol 21 (1) ◽  
pp. 241
Author(s):  
M. T. Zhao ◽  
C. S. Isom ◽  
J. G. Zhao ◽  
Y. H. Hao ◽  
J. Ross ◽  
...  

Recently neural crest derived multipotent progenitors from skin have attracted much attention as the skin may provide an accessible, autologous source of stem cells available with therapeutic potential (Toma JG et al. 2001 Nat. Cell Biol. 3, 778–784). The multipotent property of stem cells could be tracked back to the expression of specific marker genes that are exclusively expressed in multipotent stem cells rather than any other types of differentiated cells. Here we demonstrate the property of multipotency and neural crest origin of porcine GFP-transgenic skin derived progenitors (termed pSKP) in vitro by marker gene expression analysis. The pSKP cells were isolated from the back skin of GFP transgenic fetuses by serum-free selection culture in the presence of EGF (20 ng mL–1) and bFGF (40 ng mL–1), and developed into spheres in 1–2 weeks (Dyce PW et al. 2004 Biochem. Biophy. Res. Commun. 316, 651–658). Three groups of RT-PCR primers were used on total RNA from purified pSKP cells: pluripotency related genes (Oct4, Sox2, Nanog, Stat3), neural crest marker genes (p75NGFR, Slug, Twist, Pax3, Sox9, Sox10) and lineage specific genes (GFAP, tubulin β-III, leptin). Expression of both pluripotency related genes and neural crest marker genes were detected in undifferentiated pSKP cells. In addition, transcripts for fibronectin, vimentin and nestin (neural stem cell marker) were also present. The percentage of positive cells for Oct4, fibronection and vimentin were 12.3%, 67.9% and 53.7% respectively. Differentiation assays showed the appearance of tubulin β-III positive (39.4%) and GFAP-positive (42.6%) cells in cultures by immunocytochemistry, which share the characteristics of neurons and glial cells, respectively. Thus, we confirm the multiple lineage potentials and neural crest origin of pSKP cells in the level of marker gene expression. This work was funded by National Institutes of Health National Center for Research Resources RR013438.


2006 ◽  
Vol 291 (5) ◽  
pp. H2493-H2503 ◽  
Author(s):  
D. L. Tharp ◽  
B. R. Wamhoff ◽  
J. R. Turk ◽  
D. K. Bowles

A hallmark of smooth muscle cell (SMC) phenotypic modulation in atherosclerosis and restenosis is suppression of SMC differentiation marker genes, proliferation, and migration. Blockade of intermediate-conductance Ca2+-activated K+channels (IKCa1) has been shown to inhibit restenosis after carotid balloon injury in the rat; however, whether IKCa1 plays a role in SMC phenotypic modulation is unknown. Our objective was to determine the role of IKCa1 channels in regulating coronary SMC phenotypic modulation and migration. In cultured porcine coronary SMCs, platelet-derived growth factor-BB (PDGF-BB) increased TRAM-34 (a specific IKCa1 inhibitor)-sensitive K+current 20-fold; increased IKCa1 promoter histone acetylation and c- jun binding; increased IKCa1 mRNA ∼4-fold; and potently decreased expression of the smooth muscle differentiation marker genes smooth muscle myosin heavy chain (SMMHC), smooth muscle α-actin (SMαA), and smoothelin-B, as well as myocardin. Importantly, TRAM-34 completely blocked PDGF-BB-induced suppression of SMMHC, SMαA, smoothelin-B, and myocardin and inhibited PDGF-BB-stimulated migration by ∼50%. Similar to TRAM-34, knockdown of endogenous IKCa1 with siRNA also prevented the PDGF-BB-induced increase in IKCa1 and decrease in SMMHC mRNA. In coronary arteries from high fat/high cholesterol-fed swine demonstrating signs of early atherosclerosis, IKCa1 expression was 22-fold higher and SMMHC, smoothelin-B, and myocardin expression significantly reduced in proliferating vs. nonproliferating medial cells. Our findings demonstrate that functional upregulation of IKCa1 is required for PDGF-BB-induced coronary SMC phenotypic modulation and migration and support a similar role for IKCa1 in coronary SMC during early coronary atherosclerosis.


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