Mechanisms of low-density lipoprotein-induced expression of connective tissue growth factor in human aortic endothelial cells

2006 ◽  
Vol 290 (4) ◽  
pp. H1624-H1634 ◽  
Author(s):  
Mimi Sohn ◽  
Yan Tan ◽  
Bing Wang ◽  
Richard L. Klein ◽  
Maria Trojanowska ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Connective Tissue ◽  
Vascular Injury ◽  
Collagen Iv ◽  
Tissue Growth ◽  
Low Density ◽  
Aortic Endothelial Cells ◽  
Protein Levels ◽  
Human Aortic Endothelial Cells

Hyperlipidemia is a recognized risk factor for atherosclerotic vascular disease. The underlying mechanisms that link lipoproteins and vascular disease are undefined. Connective tissue growth factor (CTGF) is emerging as a key determinant of progressive fibrotic diseases, and its expression is upregulated by diabetes. To define the mechanisms through which low-density lipoproteins (LDL) promote vascular injury, we evaluated whether LDL can modulate the expression of CTGF and collagen IV in human aortic endothelial cells (HAECs). Treatment of HAECs with LDL (50 μg/ml) for 24 h produced a significant increase in the mRNA and the protein levels of CTGF and collagen IV compared with unstimulated controls. To explore the mechanisms by which LDL regulates CTGF and collagen IV expression in HAECs, we determined first if CTGF and collagen IV are downstream targets for regulation by transforming growth factor-β (TGF-β). The results demonstrated that TGF-β produced a concentration-dependent increase in the protein levels of CTGF. To assess whether the induction of CTGF in response to LDL is mediated via autocrine activation of TGF-β, HAECs were treated with LDL for 24 h in the presence and absence of anti-TGF-β neutralizing antibodies (anti-TGF-β NA). The results demonstrated that the increase in CTGF induced by LDL was significantly inhibited by the anti-TGF-β NA. To investigate the upstream mediators of TGF-β on activity of CTGF in response to LDL, HAECs were treated with LDL for 24 h in the presence and absence of cell-permeable MAPK inhibitors. Inhibition of p38mapk activities did not affect LDL-induced TGF-β1, CTGF, and collagen IV expression. On the other hand, SP-600125, a specific inhibitor of c-Jun NH2-terminal kinase, suppressed LDL-induced TGF-β, CTGF, and collagen IV expression, and PD-98059, a selective inhibitor of p44/42mapk, suppressed LDL-induced TGF-β and CTGF expression. These findings are the first to implicate the MAPK pathway and TGF-β as key players in LDL signaling, leading to CTGF and collagen IV expression in HAECs. The data also point to a potential mechanistic pathway through which lipoproteins may promote vascular injury.

scholarly journals Cyclic Stretch Induces Vascular Smooth Muscle Cells to Secrete Connective Tissue Growth Factor and Promote Endothelial Progenitor Cell Differentiation and Angiogenesis

2020 ◽  
Vol 8 ◽  
Author(s):  
Jing Yan ◽  
Wen-Bin Wang ◽  
Yang-Jing Fan ◽  
Han Bao ◽  
Na Li ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Connective Tissue ◽  
Vascular Injury ◽  
Tissue Growth ◽  
Cyclic Stretch ◽  
Endothelial Differentiation ◽  
Vascular Repair ◽  
Injury Model

Endothelial progenitor cells (EPCs) play a vital role in endothelial repair following vascular injury by maintaining the integrity of endothelium. As EPCs home to endothelial injury sites, they may communicate with exposed vascular smooth muscle cells (VSMCs), which are subjected to cyclic stretch generated by blood flow. In this study, the synergistic effect of cyclic stretch and communication with neighboring VSMCs on EPC function during vascular repair was investigated. In vivo study revealed that EPCs adhered to the injury site and were contacted to VSMCs in the Sprague–Dawley (SD) rat carotid artery injury model. In vitro, EPCs were cocultured with VSMCs, which were exposed to cyclic stretch at a magnitude of 5% (which mimics physiological stretch) and a constant frequency of 1.25 Hz for 12 h. The results indicated that stretched VSMCs modulated EPC differentiation into mature endothelial cells (ECs) and promoted angiogenesis. Meanwhile, cyclic stretch upregulated the mRNA expression and secretion level of connective tissue growth factor (CTGF) in VSMCs. Recombinant CTGF (r-CTGF) treatment promoted endothelial differentiation of EPCs and angiogenesis, and increased their protein levels of FZD8 and β-catenin. CTGF knockdown in VSMCs inhibited cyclic stretch-induced EPC differentiation into ECs and attenuated EPC tube formation via modulation of the FZD8/β-catenin signaling pathway. FZD8 knockdown repressed endothelial differentiation of EPCs and their angiogenic activity. Wnt signaling inhibitor decreased the endothelial differentiation and angiogenetic ability of EPCs cocultured with stretched VSMCs. Consistently, an in vivo Matrigel plug assay demonstrated that r-CTGF-treated EPCs exhibited enhanced angiogenesis; similarly, stretched VSMCs also induced cocultured EPC differentiation toward ECs. In a rat vascular injury model, r-CTGF improved EPC reendothelialization capacity. The present results indicate that cyclic stretch induces VSMC-derived CTGF secretion, which, in turn, activates FZD8 and β-catenin to promote both differentiation of cocultured EPCs into the EC lineage and angiogenesis, suggesting that CTGF acts as a key intercellular mediator and a potential therapeutic target for vascular repair.

scholarly journals Connective tissue growth factor acts within both endothelial cells and   cells to promote proliferation of developing   cells

2011 ◽  
Vol 108 (37) ◽  
pp. 15242-15247 ◽  
Author(s):  
M. A. Guney ◽  
C. P. Petersen ◽  
A. Boustani ◽  
M. R. Duncan ◽  
U. Gunasekaran ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Connective Tissue ◽  
Connective Tissue Growth Factor ◽  
Tissue Growth

Role of Connective Tissue Growth Factor In Endothelin-Mediated Endothelial Cell Activation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2107-2107
Author(s):  
Anna J Hernandez ◽  
Sonia Henriquez ◽  
Enrique R Maldonado ◽  
Rodeler Youte ◽  
Gregory N Prado ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factors ◽  
Endothelial Cell ◽  
Growth Factor ◽  
Connective Tissue ◽  
Cell Activation ◽  
Fold Increase ◽  
Tissue Growth ◽  
Vegf Expression ◽  
Endothelial Cell Activation

Abstract Abstract 2107 Endothelial cell activation and elevated levels of circulating Endothelin-1 (ET-1) have been reported in patients with atherosclerosis and sickle cell disease (SCD). ET-1 is a well-described vasoconstrictor, mitogen and regulator of endothelial cells migration that has been shown to promote structural changes in blood vessels. ET-1 is produced in response to increases in vasoactive hormones, growth factors, hypoxia, shear stress and free radicals, events that are commonly observed in patients with SCD. Endothelial cell activation is in part characterized by increases of cytokines such as monocyte chemotactic protein-1 (MCP-1) and growth factors that are important in vascular maintenance and fibrogenesis such as connective tissue growth factor (CTGF) and vascular endothelial growth factor (VEGF). CTGF and VEGF are important for blood vessel remodeling, fibrogenesis and angiogenesis. Indeed there is evidence that incubation of smooth muscle cells with ET-1 leads to increases in CTGF and VEGF levels. However, the relationship between ET-1 and CTGF in endothelial cell activation is unclear. We hypothesize that increasing ET-1 would stimulate CTGF production and endothelial cell activation. We studied the effects of ET-1 on the human endothelial cell line, EA.hy926 (EA), as well as in primary cultures of mouse aortic endothelial cells (MAEC). We performed gene expression time course experiments (0, 2, 4, 8, 16, 24 Hr) on EA cells following incubation with 100nM ET-1 using quantitative RT-PCR with Taqman chemistries and GAPDH and beta-actin as endogenous controls. We observed increases of CTGF and VEGF expression between 4 and 8 hr for CTGF (1.74 fold increase vs time 0, n=6, P<0.03) and 4 hr for VEGF (2.14 fold increase vs time 0, n=3, P<0.04). Additional experiments on EA cells showed that incubation with 100nM ET-1 for 4 hr in the presence of BQ123 and BQ788, two inhibitors of ET-1 type A and B receptors, respectively, blocked the ET-1 stimulated rises in CTGF and VEGF as well as MCP-1 expression. We then performed western blot analyses (Abcam-CTGF antibody ab6992; Abcam VEGF antibody ab1316) and showed increases in cell associated CTGF protein levels following incubation of EA cells with 100nM ET-1 for 24 hr. The ET-1 stimulated rise in CTGF levels were significantly blunted by pre-incubation of EA cells with both BQ788 and BQ123. To study whether the effects of ET-1 were unique to EA cells, we also analyzed the effects of ET-1 on early cultures of MAEC isolated from C57BLJ mice. Consistent with our observations in human endothelial cells, incubation of MAEC with 100nM ET-1 for 4 hr were associated with increases of CTGF and VEGF expression (1.86 fold vs vehicle, n=3, P<0.03; 1.73 fold vs vehicle, n=3 P<0.04 respectively). Furthermore, ET-1 stimulated rises in CTGF and VEGF expressions were likewise blocked by pre-incubation with BQ123 andBQ788. We conclude that addition of ET-1 leads to activation of endothelial cells and increases in CTGF and VEGF from human and mouse endothelial cells. Thus we suggest that therapies designed to block ET-1 receptors will reduce endothelial cell activation in part by reducing CTGF production leading to alterations in cellular and tissue architecture. This work was supported by NIH R01HL090632 to AR and R01HL096518 to JRR. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Low-Density Lipoprotein Induced Expression of Connective Tissue Growth Factor via Transactivation of Sphingosine 1-Phosphate Receptors in Mesangial Cells

2012 ◽  
Vol 26 (5) ◽  
pp. 833-845 ◽  
Author(s):  
Hesham M. El-Shewy ◽  
Mimi Sohn ◽  
Parker Wilson ◽  
Mi Hye Lee ◽  
Samar M. Hammad ◽  
...  
Keyword(s):  
Growth Factor ◽  
Connective Tissue ◽  
Connective Tissue Growth Factor ◽  
Pertussis Toxin ◽  
Mesangial Cells ◽  
Tissue Growth ◽  
Low Density ◽  
Induced Expression ◽  
Sphingosine 1 Phosphate ◽  
S1p Receptor

Abstract The pro-fibrotic connective tissue growth factor (CTGF) has been linked to the development and progression of diabetic vascular and renal disease. We recently reported that low-density lipoproteins (LDL) induced expression of CTGF in aortic endothelial cells. However, the molecular mechanisms are not fully defined. Here, we have studied the mechanism by which LDL regulates CTGF expression in renal mesangial cells. In these cells, treatment with pertussis toxin abolished LDL-stimulated activation of ERK1/2 and c-Jun N-terminal kinase (JNK), indicating the involvement of heterotrimeric G proteins in LDL signaling. Treatment with LDL promoted activation and translocation of endogenous sphingosine kinase 1 (SK1) from the cytosol to the plasma membrane concomitant with production of sphingosine-1-phosphate (S1P). Pretreating cells with SK inhibitor, dimethylsphinogsine or down-regulation of SK1 and SK2 revealed that LDL-dependent activation of ERK1/2 and JNK is mediated by SK1. Using a green fluorescent protein-tagged S1P1 receptor as a biological sensor for the generation of physiologically relevant S1P levels, we found that LDL induced S1P receptor activation. Pretreating cells with S1P1/S1P3 receptor antagonist VPC23019 significantly inhibited activation of ERK1/2 and JNK by LDL, suggesting that LDL elicits G protein-dependent activation of ERK1/2 and JNK by stimulating SK1-dependent transactivation of S1P receptors. Furthermore, S1P stimulation induced expression of CTGF in a dose-dependent manner that was markedly inhibited by blocking the ERK1/2 and JNK signaling pathways. LDL-induced CTGF expression was pertussis toxin sensitive and inhibited by dimethylsphinogsine down-regulation of SK1 and VPC23019 treatment. Our data suggest that SK1-dependent S1P receptor transactivation is upstream of ERK1/2 and JNK and that all three steps are required for LDL-regulated expression of CTGF in mesangial cells.

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