Smooth muscle cell surface tissue factor pathway activation by oxidized low-density lipoprotein requires cellular lipid peroxidation (original) (raw)
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Atherosclerosis, 2006
Increase in plasma low density lipoprotein (LDL) levels and/or decrease in high density lipoprotein (HDL) levels are major risk factors for the development of atherosclerosis. An oxidative modification of LDL represents a key process in atherogenesis. It is well known that the LDL/HDL ratio is more important than the individual LDL and HDL levels to predict atherosclerosis. The purpose of our study was to investigate the effects of mildly oxidized LDL (minimally modified LDL: MM-LDL) and HDL, administrated alone or in combination, on the production and release of basic fibroblast growth factor (bFGF) by bovine aortic smooth muscle cells (SMCs) in culture. MM-LDL and HDL have opposite effects on aortic SMCs: MM-LDL increases both bFGF production and release and SMC proliferation, while HDL decreases both bFGF production and release and SMC proliferation. The effects of either MM-LDL or HDL on SMCs are mediated through a Giprotein-coupled receptor. The simultaneous treatment of SMCs with MM-LDL and HDL (MM-LDL/HDL ratio = 4.0) produced the inhibition of MM-LDL effects. Our data suggest that the protective role of HDL could also be exerted through the inhibition of the pro-atherosclerotic effects of MM-LDL on SMCs.
Biochemistry and molecular biology international
The effect of cupric ions or endothelial cell-oxidized LDL on the transcription factor NFKB activation was investigated by electrophoretic mobility shift assay. Oxidized LDL induced NFkB activation in fibroblasts, endothelial and smooth muscle cells. The extent of NF~:B activation was proportional to the degree of LDL oxidation, as assessed by the lipid peroxidation product and the conjugated diene level. A similar activation was observed with the lipid extract of copper-oxidized LDL, which indicates that lipid peroxidation products are involved in the activation mechanism. Furthermore, cz-tocophe/,ol, a lipophilic free radical scavenger, partially inhibited the stimulatory effect of CuZ+-oxidized LDL. Since NFKB is considered as an oxidative stress-responsive transcription factor, our study supports the evidence that the stress induced by oxidized LDL causes NFKB activation in different cell types, and that this effect can be ascribed to the lipid peroxidation products.
IUBMB Life, 1996
The effect of cupric ions or endothelial cell-oxidized LDL on the transcription factor NFKB activation was investigated by electrophoretic mobility shift assay. Oxidized LDL induced NFkB activation in fibroblasts, endothelial and smooth muscle cells. The extent of NF~:B activation was proportional to the degree of LDL oxidation, as assessed by the lipid peroxidation product and the conjugated diene level. A similar activation was observed with the lipid extract of copper-oxidized LDL, which indicates that lipid peroxidation products are involved in the activation mechanism. Furthermore, cz-tocophe/,ol, a lipophilic free radical scavenger, partially inhibited the stimulatory effect of CuZ+-oxidized LDL. Since NFKB is considered as an oxidative stress-responsive transcription factor, our study supports the evidence that the stress induced by oxidized LDL causes NFKB activation in different cell types, and that this effect can be ascribed to the lipid peroxidation products.
Journal of Atherosclerosis and Thrombosis, 2011
Oxidized low-density lipoprotein (oxLDL) interacts with macrophages and is implicated in atherogenesis. Macrophages are also the major source within the atherosclerotic plaque of tissue factor (TF), the membrane-bound glycoprotein receptor that triggers the coagulation cascade in vivo and contributes to plaque thrombogenicity. In this study we tested the hypothesis that oxLDL modulates TF expression in human monocyte-derived macrophages (MDMs). Methods: Mononuclear cells were isolated from human blood, allowed to differentiate into MDMs during 8 days in cell culture, and then exposed to varying concentrations of oxLDL in the presence or absence of lipopolysaccharide (LPS). TF procoagulant activity (TF-PCA) of MDMs was measured by one-stage recalcification clotting assay using human recombinant TF as standard. TF protein was evaluated by Western blotting, and TF mRNA was determined by Northern blot analysis. Results: OxLDL at 5-10 g/mL increased TF-PCA, TF protein, and mRNA in MDMs, whereas 20-100 g/mL oxLDL inhibited TF-PCA, protein expression, and mRNA expression in these cells even in the face of LPS stimulation. Conclusions: Low concentrations of oxLDL enhance TF expression in MDMs, whereas higher concentrations attenuate TF expression both at baseline as well as following LPS stimulation. Both TF-PCA and TF protein follow this dose-response pattern that is preceded by concordant mRNA changes. Thus, we have demonstrated modulation by oxLDL of TF protein and bioactivity in MDMs.
Novel Effect of Oxidized Low-Density Lipoprotein
Circulation Research, 2006
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a classical glycolytic enzyme that is involved in cellular energy production and has important housekeeping functions. We used the natural prooxidant and proatherogenic molecule oxidized low-density lipoprotein (OxLDL) to determine a potential link between OxLDL-promoted oxidative stress, GAPDH expression, and smooth muscle cell energy metabolism. OxLDL but not native LDL (nLDL) produced a 60% to 100% dose- and time-dependent reduction of GAPDH protein. OxLDL increased reactive oxygen species (ROS) formation, including rapid elevation of H 2 O 2 levels. OxLDL decreased intracellular catalase expression, likely contributing to the increase in H 2 O 2 . Antioxidants, anti-CD36 receptor antibody, NADPH oxidase, or lipoxygenase blockers decreased OxLDL-specific ROS and prevented GAPDH downregulation. 12/15-Lipoxygenase or p47phox deficiency resulted in attenuation of GAPDH downregulation, but 5-lipoxygenase suppression had no effect. O...
Cardiovascular Research, 2001
Death of vascular smooth muscle cell (VSMC) induced by oxidized LDL (oxLDL) can occur by both necrosis and apoptosis which may contribute to plaque instability and rupture. Reactive oxygen species (ROS) induces apoptosis in VSMC and is involved in oxLDL action, we tested the hypothesis here that a coupling exists between ROS generation and apoptosis of oxLDL-treated VSMC. Cultured VSMC from rat aorta were treated with oxLDL, apoptosis and necrosis were distinguished by using FITC-annexin V label and propidium iodide stain, analyzed by flow cytometry. ROS generation of VSMCs was detected by the fluorescence intensity of DCF. Apoptosis was also determined by cleavage of procaspase-3. OxLDL induced apoptosis (3 h) in a dose-dependent manner and reached maximum (with near-basal necrosis) at a concentration of 300 microg/ml. At this and lower (100 microg/ml) concentration, oxLDL, but not native LDL, stimulated ROS production rapidly (< or =5 min) and ROS level remained elevated for at least 45 min. Catalase and deferoxamine reduced both oxLDL-induced apoptosis and ROS generation. Superoxide dismutase and benzoic acid neither reduced the oxLDL-induced ROS generation nor inhibited apoptosis. Since oxLDL-induced ROS generation were inhibited by nordihydroguaiaretic acid and rotenone, lipoxygenase and mitochondrial pathways could be involved. In addition, catalase, deferoxamine, and N-acetylcysteine inhibited oxLDL-induced cleavage of procaspase-3 as well. ROS generation and apoptosis are tightly coupled in oxLDL-treated VSMCs. Antioxidants that reduced ROS level inhibited apoptosis, those that did not reduce ROS level were ineffective. Both mitochondrial and lipoxygenase activities may be involved.
Life Sciences, 1998
The effects were studied of native, partially-oxidized and totally-oxidized human low-density lipoprotein (LDL) on the proliferation of cultured rat aortic smooth muscle cells (VSMC), measured as an altered DNA synthesis. The LDL was obtained from three different human long-term diet groups (a control diet rich in saturated fats, a vegetarian diet, and a fish diet). The oxidized LDLs were prepared by oxidizing the LDL with copper sulfate. The DNA synthesis was measured by [3H]-thymidine incorporation into the DNA. The partially-oxidized LDL was the most potent promoter of DNA synthesis compared to the native or totally-oxidized LDL of the same diet group. The partially-oxidized LDL had a true mitogenic effect in the absence of exogenous growth factors. The native and totally-oxidized LDL induced a significant increase in DNA synthesis, if they were obtained from the fish diet group. This study suggests an enhanced proliferative effect of partiallyoxidized LDL on VSMC growth.