u-0126 and Atherosclerosis

Topics: Animals; Atherosclerosis; Butadienes; Drug Synergism; Fatty Liver; Female; Hypertriglyceridemia; Ligands; Lipids; Liver X Receptors; Male; Mice, Knockout; Mitogen-Activated Protein Kinase Kinases; Nitriles; Plaque, Atherosclerotic; Protein Kinase Inhibitors; Receptors, LDL

Atherosclerosis is a chronic inflammatory disease, which is thought to be one of the most common causes of death globally. The functions of macrophage in the development of atherosclerosis inflammation still get more attention. Although lipopolysaccharide (LPS) can trigger inflammation in atherosclerosis, how LPS promotes atherogenesis through acting on macrophage is not very clear. Here, we study the role of adipophilin in LPS-induced inflammation. After RAW264.7 cells were treated with LPS of different concentrations, the protein level of adipophilin was increased dose-dependently, and cells treated with LPS for various time were observed the highest levels of TNF-α, MCP-1, and IL-6 at 12 h. In addition, inhibited extracellular signal-regulated kinase (ERK)-1/2 presented lower levels of adipophilin, peroxisome proliferator-activated receptor gamma (PPARγ), TNF-α, MCP-1, as well as IL-6. But inhibited PPARγ, the levels of adipophilin, TNF-α, MCP-1, and IL-6 were significantly augmented. Moreover, after silence adipophilin, the ERK1/2 activity and protein level of PPARγ were not influenced, whereas the levels of TNF-α, MCP-1, and IL-6 were significantly reduced. LPS can promote the expression of adipophilin through ERK1/2-PPARγ pathway, whereby it enhances the secretion levels of TNF-α, MCP-1, and IL-6.

Topics: Animals; Atherosclerosis; Butadienes; Cytokines; Extracellular Signal-Regulated MAP Kinases; Inflammation; Lipopolysaccharides; Macrophages; MAP Kinase Signaling System; Mice; Nitriles; Perilipin-2; PPAR gamma; Protein Kinase Inhibitors; RAW 264.7 Cells; RNA, Small Interfering; Signal Transduction

Expression of ATP-binding cassette transporter G1 (ABCG1), a molecule facilitating cholesterol efflux to HDL, is activated by liver X receptor (LXR). In this study, we investigated if inhibition of ERK1/2 can activate macrophage ABCG1 expression and functions. MEK1/2 inhibitors, PD98059 and U0126, increased ABCG1 mRNA and protein expression, and activated the natural ABCG1 promoter but not the promoter with the LXR responsive element (LXRE) deletion. Inhibition of ABCG1 expression by ABCG1 siRNA did enhance the formation of macrophage/foam cells and it attenuated the inhibitory effect of MEK1/2 inhibitors on foam cell formation. MEK1/2 inhibitors activated macrophage cholesterol efflux to HDL in vitro, and they enhanced reverse cholesterol transport (RCT) in vivo. ApoE deficient (apoE(-/-)) mice receiving U0126 treatment had reduced sinus lesions in the aortic root which was associated with activated macrophage ABCG1 expression in the lesion areas. MEK1/2 inhibitors coordinated the RXR agonist, but not the LXR agonist, to induce ABCG1 expression. Furthermore, induction of ABCG1 expression by MEK1/2 inhibitors was associated with activation of SIRT1, a positive regulator of LXR activity, and inactivation of SULT2B1 and RIP140, two negative regulators of LXR activity. Taken together, our study suggests that MEK1/2 inhibitors activate macrophage ABCG1 expression/RCT, and inhibit foam cell formation and lesion development by multiple mechanisms, supporting the concept that ERK1/2 inhibition is anti-atherogenic.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; ATP Binding Cassette Transporter, Subfamily G, Member 1; Biological Transport; Butadienes; Cholesterol; Flavonoids; Foam Cells; Gene Expression Regulation; Humans; Liver X Receptors; Macrophages; MAP Kinase Kinase 1; MAP Kinase Signaling System; Mice; Mice, Knockout; Nitriles; Promoter Regions, Genetic; Retinoid X Receptor alpha; Sirtuin 1

Intraplaque angiogenesis has been recognized as an important risk factor for the rupture of advanced atherosclerotic plaques in recent years. CD147, also called Extracellular Matrix Metalloproteinase Inducer, has been found the ability to promote angiogenesis in many pathological conditions such as cancer diseases and rheumatoid arthritis via the up-regulation of vascular endothelial growth factor (VEGF), a critical mediator of angiogenesis. We investigated whether CD147 would also induce the up-regulation of VEGF in the foam cells formation process and explored the probable signaling pathway. The results showed the expression of CD147 and VEGF was significantly higher in U937-derived foam cells. After CD147 stealth siRNA transfection treatment, the production of VEGF was reduced depended on the inhibition efficiency of CD147 siRNAs.The special signaling pathway inhibitors LY294002, SP600125, SB203580 and U0126 were added to cultures respectively and the results showed LY294002 dose-dependently inhibited the expression of VEGF. The reduction of phospho-Akt was observed in both LY294002 and siRNA groups, suggested that the phosphatidylinositol 3-kinase/Akt pathway may be the probable signaling pathway underlying CD147 induced up-regulation of VEGF in U937-derived foam cells.

Topics: Anthracenes; Atherosclerosis; Basigin; Butadienes; Chromones; Flow Cytometry; Foam Cells; Gene Expression Regulation; Gene Silencing; Humans; Imidazoles; Lipoproteins, LDL; Morpholines; Nitriles; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Pyridines; Signal Transduction; U937 Cells; Up-Regulation; Vascular Endothelial Growth Factor A

Activation of liver X receptor (LXR) inhibits atherosclerosis but induces hypertriglyceridemia. In vitro, it has been shown that mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor synergizes LXR ligand-induced macrophage ABCA1 expression and cholesterol efflux. In this study, we determined whether MEK1/2 (U0126) and LXR ligand (T0901317) can have a synergistic effect on the reduction of atherosclerosis while eliminating LXR ligand-induced fatty livers and hypertriglyceridemia. We also set out to identify the cellular mechanisms of the actions.. Wild-type mice were used to determine the effect of U0126 on a high-fat diet or high-fat diet plus T0901317-induced transient dyslipidemia and liver injury. ApoE deficient (apoE(-/-)) mice or mice with advanced lesions were used to determine the effect of the combination of T0901317 and U0126 on atherosclerosis and hypertriglyceridemia. We found that U0126 protected animals against T0901317-induced transient or long-term hepatic lipid accumulation, liver injury, and hypertriglyceridemia. Meanwhile, the combination of T0901317 and U0126 inhibited the development of atherosclerosis in a synergistic manner and reduced advanced lesions. Mechanistically, in addition to synergistic induction of macrophage ABCA1 expression, the combination of U0126 and T0901317 maintained arterial wall integrity, inhibited macrophage accumulation in aortas and formation of macrophages/foam cells, and activated reverse cholesterol transport. The inhibition of T0901317-induced lipid accumulation by the combined U0126 might be attributed to inactivation of lipogenesis and activation of lipolysis/fatty acid oxidation pathways.. Our study suggests that the combination of mitogen-activated protein kinase kinase 1/2 inhibitor and LXR ligand can function as a novel therapy to synergistically reduce atherosclerosis while eliminating LXR-induced deleterious effects.

Topics: Animals; Aorta; Aortic Diseases; Apolipoproteins E; Atherosclerosis; Butadienes; Chemical and Drug Induced Liver Injury; Cholesterol; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Fatty Liver; Female; Foam Cells; Hep G2 Cells; Humans; Hydrocarbons, Fluorinated; Hypertriglyceridemia; Liver; Liver X Receptors; Male; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Nitriles; Orphan Nuclear Receptors; Protein Kinase Inhibitors; Signal Transduction; Sulfonamides

Matrix metalloproteinases (MMP) play a pivotal role in the pathogenesis of cardiovascular diseases. Their expressions are altered in response to a variety of stimuli, including growth factors, inflammatory markers, and cytokines. In this study, we demonstrated that platelet-derived growth factor-BB (PDGF-BB) induces a dose- and time-dependent increase in MMP-2 expression in rat vascular smooth muscle cells (VSMC). Treatment with either the Rho-associated protein kinase (ROCK) inhibitor Y-27632 or suppression of ROCK-1/2 by small interfering RNA technology significantly reduced the MMP-2 expression, thus suggesting that ROCK regulates such expression. Similar results were observed when VSMC were pretreated with either U0126 or SB203580, which are selective inhibitors of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase, respectively, thus suggesting that these kinases are important for the induction of MMP-2 expression by PDGF-BB. In conclusion, these results described a novel mechanism in atherosclerosis through PDGF-BB signaling in VSMC, in which MMP-2 expression is induced via extracellular signal-regulated kinases and p38 mitogen-activated protein kinase phosphorylation, as well as ROCK.

Topics: Amides; Animals; Aorta; Atherosclerosis; Becaplermin; Butadienes; Cell Line; Cell Movement; Gene Expression Regulation; Humans; Imidazoles; Matrix Metalloproteinase 2; Muscle, Smooth, Vascular; Nitriles; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-sis; Pyridines; Rats; rho-Associated Kinases

Increased plasma concentrations of apolipoprotein B100 often present in patients with insulin resistance and confer increased risk for the development of atherosclerosis. Naturally occurring polyphenolic compounds including flavonoids have antiatherogenic properties. The aim of the current study was to evaluate the effect of the polymethoxylated flavonoid nobiletin on lipoprotein secretion in cultured human hepatoma cells (HepG2) and in a mouse model of insulin resistance and atherosclerosis.. Lipoprotein secretion was determined in HepG2 cells incubated with nobiletin or insulin. mRNA abundance was evaluated by quantitative real-time PCR, and Western blotting was used to demonstrate activation of cell signaling pathways. In LDL receptor-deficient mice (Ldlr(-/-)) fed a Western diet supplemented with nobiletin, metabolic parameters, gene expression, fatty acid oxidation, glucose homeostasis, and energy expenditure were documented. Atherosclerosis was quantitated by histological analysis.. In HepG2 cells, activation of mitogen-activated protein kinase-extracellular signal-related kinase signaling by nobiletin or insulin increased LDLR and decreased MTP and DGAT1/2 mRNA, resulting in marked inhibition of apoB100 secretion. Nobiletin, unlike insulin, did not induce phosphorylation of the insulin receptor or insulin receptor substrate-1 and did not stimulate lipogenesis. In fat-fed Ldlr(-/-) mice, nobiletin attenuated dyslipidemia through a reduction in VLDL-triglyceride (TG) secretion. Nobiletin prevented hepatic TG accumulation, increased expression of Pgc1α and Cpt1α, and enhanced fatty acid β-oxidation. Nobiletin did not activate any peroxisome proliferator-activated receptor (PPAR), indicating that the metabolic effects were PPAR independent. Nobiletin increased hepatic and peripheral insulin sensitivity and glucose tolerance and dramatically attenuated atherosclerosis in the aortic sinus.. Nobiletin provides insight into treatments for dyslipidemia and atherosclerosis associated with insulin-resistant states.

Topics: Animals; Atherosclerosis; Butadienes; Diet; Dyslipidemias; Electrophoresis, Polyacrylamide Gel; Energy Metabolism; Enzyme Inhibitors; Flavones; Hep G2 Cells; Humans; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Lipoproteins, VLDL; Male; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Mice; Mice, Mutant Strains; Nitriles; Phosphorylation; Receptor, Insulin; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Triglycerides

Many studies indicated that the CD40/CD40 ligand (CD40L) pathway plays an important role in the pathogenesis of atherosclerosis. It has been demonstrated a protective role of dehydroepiandrosterone (DHEA) against atherosclerosis. The major purpose of our present work was to assess whether DHEA could decrease the expression of CD40 and CD40L on human umbilical vein endothelial cells (HUVECs) induced by interferon gamma (IFN-gamma). We found that DHEA inhibited IFN-gamma-induced expression of CD40 and CD40L in a dose-dependent manner. Moreover, DHEA inhibited IFN-gamma-induced activation of extracellular signal regulated kinase (ERK1/2). The important role of ERK1/2 in DHEA effect was further confirmed by using ERK1/2 inhibitor U0126. These findings suggest that DHEA can inhibit the expression of molecules involved in the inflammatory process in endothelial cells activated with IFN-gamma. Such antagonism is at least partially mediated through the modulation of ERK1/2 pathway. Therefore, DHEA may be considered as a potential preventive intervention for atherosclerosis.

Topics: Adjuvants, Immunologic; Atherosclerosis; Butadienes; CD40 Antigens; CD40 Ligand; Cells, Cultured; Dehydroepiandrosterone; Endothelium, Vascular; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Humans; Interferon-gamma; Nitriles; Signal Transduction; Umbilical Veins

Increase in the expression of leukocyte antigen-related (LAR) protein causes insulin resistance, an important contributor to atherosclerosis. However, the function of LAR in atherosclerosis is not known. To address whether LAR is important in the response of vascular cells to atherogenic stimuli, we investigated cell proliferation, migration, and insulin-like growth factor-1 receptor (IGF-1R) signaling in wild-type and LAR(-/-) mouse vascular smooth muscle cells (VSMC) treated with IGF-1. Absence of LAR significantly enhanced proliferation and migration of VSMC compared with wild-type cells after IGF-1 treatment. U0126 and LY249002, specific inhibitors of MAPK/ERK kinase (MEK) and phosphoinositide 3-kinase, respectively, inhibited IGF-1-induced DNA synthesis and migration in both wild-type and LAR(-/-) VSMC. IGF-1 markedly enhanced IGF-1R phosphorylation in both wild-type and LAR(-/-) VSMC, but the phosphorylation was 90% higher in knock-out cells compared with wild-type cells. Absence of LAR enhanced phosphorylation of insulin receptor substrate-1 and insulin receptor substrate-1-associated phosphoinositide 3-kinase activity in VSMC treated with IGF-1. IGF-1-induced phosphorylation of ERK1/2 also increased significantly in LAR(-/-) VSMC compared with wild-type cells. Furthermore, LAR directly binds to IGF-1R in glutathione S-transferase-LAR pull-down and IGF-1R immunoprecipitation experiments and recombinant LAR dephosphorylates IGF-1R in vitro. Neointima formation in response to arterial injury and IGF-1R phosphorylation in neointima increased significantly in LAR(-/-) mice compared with wild-type mice. A significant decrease in body weight, fasting insulin, and IGF-1 levels were observed in LAR(-/-) mice compared with wild-type mice. Together, these data indicate that LAR regulates IGF-1R signaling in VSMC and dysregulation of this phosphatase may lead to VSMC hyperplasia.

Topics: Animals; Arteries; Atherosclerosis; Butadienes; Cell Movement; Cell Proliferation; Cells, Cultured; Enzyme Inhibitors; Humans; Hyperplasia; Insulin Resistance; Insulin-Like Growth Factor I; Male; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Mice; Mice, Knockout; Nitriles; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Binding; Protein Processing, Post-Translational; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Protein Tyrosine Phosphatases; Receptor-Like Protein Tyrosine Phosphatases, Class 4; Receptor, IGF Type 1; Receptors, Cell Surface; Tunica Media