UMLS:C0004153 - FACTA Search

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Query: UMLS:C0004153 (atherosclerosis)
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We investigated the effects of high concentrations of glucose on plasminogen activator inhibitor-1 (PAI-1) gene expression in cultured rat vascular smooth muscle cells (VSMC). In response to a high glucose concentration (27.5 mM), PAI-1 mRNA increased within 2 h, peaked at 4 h, remained elevated for another 4 h, then decreased to basal levels at 24 h. On the other hand, mannose at the same concentration (22.5 mM mannose plus 5.5 mM glucose) as an osmotic control had little effect on PAI-1 mRNA expression. The expression of PAI-1 mRNA that was also increased by H(2)O(2), angiotensin II, or phorbol myristate acetate, was reversed by the MAPK kinase (MEK) inhibitor PD98059 or the specific protein kinase C (PKC) inhibitor GF109203X. High glucose appeared to activate MAPK and PKC in VSMC judging from Elk-1 and AP-1 activation, respectively. PD98059 inhibited and GF109203X prevented subsequent PAI-1 induction by glucose. These results suggest that glucose at high concentrations induces PAI-1 gene expression in VSMC at least partially via MAPK and PKC activation. This direct effect of glucose might have important implications for the increased plasma concentrations of PAI-1 and possibly atherosclerosis that are associated with diabetes.
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PMID:Glucose upregulates plasminogen activator inhibitor-1 gene expression in vascular smooth muscle cells. 1240 45

In the past decade, substantial progress has been made concerning our knowledge of bioactive components in plant foods and their links to health. Human diets of plant origin contain many hundreds of compounds which cannot be considered as nutrients, but appear to play a role in the maintenance of health. These substances are called nutraceuticals. In some cases where the disease process is at least partially understood, elements of protection can be related to a single compound or structurally related group of compounds in the diet. Bioactive components of food which are of special interest include the following groups: polyphenols, phytoestrogens, phytosterols, phytates and polyunsaturated fatty acids. Most of them are featured by antioxidant properties. In the first part of this review, we indicate the main groups of bioactive compounds giving a description of their localisation, chemical properties and biological actions. Recently, it was shown, however, that the bioavailability of potential antioxidants from plant foods is generally too low to have any substantial direct effect on reactive oxygen species. As a result of that it is postulated that dietary compounds, even in very low concentrations, may have a far greater impact than previously appreciated on the regulation of gene expression. The second part of this paper concerns the action of the literally most important bioactive substances on the molecular mechanisms of the control of genes which in turn affect cellular metabolism. A few current studies on the action of selected nutraceuticals on the activity of transcription factors such as AP-1, NF-kappaB, SREBPs, PPARs as final targets in the signal transduction cascade and gene regulation are included. A detailed analysis of numerous factors of dietary origin with their targets is far beyond the scope of this paper. However, continuing research on the effects of nutraceuticals on gene expression should provide insight into the mechanisms of prevention of diseases such as obesity, diabetes, atherosclerosis, hypertension and cancer by dietary manipulations.
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PMID:Bioactive substances of plant origin in food--impact on genomics. 1253 56

Biochemical and genetic evidence support the involvement of leukocyte-type 12/15-lipoxygenase enzyme and its products in the atherogenic process. We recently showed that products of the 12/15-lipoxygenase pathway play an important role in mediating hypertrophy, matrix protein production, and inflammatory gene expression in vascular smooth muscle cells (VSMC) through activation of mitogen activated protein kinases and key transcription factors. The current study is aimed at establishing the in vivo role of 12/15-lipoxygenase in VSMC by comparing growth factor-induced responses in VSMC derived from 12/15-lipoxygenase knockout mice versus genetic control wild-type mice. In the lipoxygenase knockout cells, 12/15-lipoxygenase protein was not expressed, and levels of its product, 12(S)-hydroxyeicosatetraenoic acid, were reduced (51% of wild type). Knockout cells exhibited significantly lower rates of growth factor-induced migration, fibronectin production, and incorporation of 3H-thymidine and 3H-leucine (54%, 55%, 61%, and 57% of wild type, respectively). Growth factor-induced superoxide production and p38 mitogen-activated protein kinase activation were also reduced in knockout cells. Serum-stimulated AP-1 transcription factor activation was markedly reduced (50% of wild type), whereas cAMP response element binding protein activation was abrogated in knockout cells. Furthermore, growth factor-induced mRNA expression of immediate early genes and fibronectin were also greatly reduced. These results suggest that the modulation of specific signaling pathways and growth-responsive genes may be responsible for the altered growth factor responses in the lipoxygenase knockout cells. They also demonstrate the important in vivo role of vascular 12/15-lipoxygenase in VSMC growth, migration, and matrix responses associated with hypertension, atherosclerosis, and restenosis.
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PMID:Reduced growth factor responses in vascular smooth muscle cells derived from 12/15-lipoxygenase-deficient mice. 1270 89

Low density lipoprotein (LDL) exists in various forms that possess unique characteristics, including particle content and metabolism. One circulating subfraction, electronegative LDL (LDL(-)), which is increased in familial hypercholesterolemia and diabetes, is implicated in accelerated atherosclerosis. Cellular responses to LDL(-) remain poorly described. Here we demonstrate that LDL(-) increases tumor necrosis factor alpha (TNFalpha)-induced inflammatory responses through NF kappa B and AP-1 activation with corresponding increases in vascular cell adhesion molecule-1 (VCAM1) expression. LDL receptor overexpression increased these effects. In contrast, exposing LDL(-) to the key lipolytic enzyme lipoprotein lipase (LPL) reversed these responses, inhibiting VCAM1 below levels seen with TNFalpha alone. LPL is known to act on lipoproteins to generate endogenous peroxisomal proliferator-activated receptor alpha (PPAR alpha) ligand, thus limiting inflammation. These responses varied according to the lipoprotein substrate triglyceride content (very low density lipoprotein >> LDL > high density lipoprotein). The PPAR alpha activation seen with LDL, however, was disproportionately high. We show here that MUT LDL activates PPAR alpha to an extent proportional to its LDL(-) content. As compared with LDL(-) alone, LPL-treated LDL(-) increased PPAR alpha activation 20-fold in either cell-based transfection or radioligand displacement assays. LPL-treated LDL(-) suppressed NF kappa B and AP-1 activation, increasing expression of the PPAR alpha target gene I kappa B alpha, although only in the genetic presence of PPAR alpha and with intact LPL hydrolysis. Mass spectrometry reveals that LPL-treatment of either LDL or LDL(-) releases hydroxy-octadecadienoic acids (HODEs), potent PPAR alpha activators. These findings suggest LPL-mediated PPAR alpha activation as an alternative catabolic pathway that may limit inflammatory responses to LDL(-).
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PMID:Dual roles for lipolysis and oxidation in peroxisome proliferation-activator receptor responses to electronegative low density lipoprotein. 1287 89

Monocyte infiltration followed by differentiation into macrophages and accumulation of oxidised LDL (oxLDL) comprise early stages of atherosclerosis. Vascular endothelial growth factor (VEGF), which is upregulated by oxLDL, may contribute to atherogenesis through monocyte recruitment, increased vascular permeability and promotion of intraplaque vessels. The VEGF receptor-1 (VEGFR-1/Flt-1) mediates monocyte migration towards VEGF and regulates the levels of available VEGF through ligand-entrapment. In this study we investigated the effect of oxLDL on VEGFR-1 expression in human monocyte-derived macrophages. mRNA expression was estimated using RT-PCR, protein secretion was measured with ELISA and the amount of membrane-bound VEGFR-1 was analysed using flow cytometry analysis. Binding of transcription factors to the promoter was studied with EMSA. Incubation with oxLDL decreased VEGFR-1 mRNA expression in a time- and dose-dependent manner, followed by a subsequent decrease in protein secretion of VEGFR-1 and a reduction of the amount of receptor expressed on the cell surface. Furthermore, the PPARgamma agonists 9-hydroxy-(S)-10,12-octadecadienoic acid (9-HODE) and darglitazone also decreased VEGFR-1 mRNA expression. Incubation of macrophages with oxLDL or 9-HODE decreased binding of the transcription factor AP-1 (c-jun/ATF-2) to the VEGFR-1 promoter. Together, these data suggest that oxLDL decreases VEGFR-1 expression in macrophages, probably through a PPARgamma-dependent reduction in the AP-1 transcriptional activity. This implies that oxLDL has effects on the biological availability of VEGF, besides its direct effect on VEGF expression.
Atherosclerosis 2003 Aug
PMID:Oxidised LDL decreases VEGFR-1 expression in human monocyte-derived macrophages. 1292 77

We have been analysing the signalling systems that couple to receptors of the TIR (Toll/interleukin-1 receptor) family, which signal through a common cytoplasm region; the TIR domain. These systems are of both practical and fundamental biological significance, being central to the pathogenesis of chronic inflammatory diseases such as atherosclerosis, to host defence throughout the biological world, and are ancient in the context of life on earth, having originated more than 1 billion years ago: prior to the divergence of plants and animals. TIR domain receptors couple to at least two sets of well-characterized pathways: those leading to the activation of inhibitory kappaB kinase complexes/nuclear factor kappaB, and those leading to the activation of mitogen-activated protein kinase/AP-1/ATF-2 etc. We have been investigating these systems using a combination of expression screening methods to identify new components, and real-time green fluorescent protein-based techniques to observe execution of signalling programmes in real time. Our data reveal that there is a very large level of cell-to-cell variation in signal programme execution even in clonal populations and that at least one mechanism for dealing with this heterogeneity is the assembly of signal transduction components into large multiprotein complexes.
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PMID:Signalling networks, inflammation and innate immunity. 1464 Oct 90

In a variety of vascular disorders, endothelial cells (ECs) are exposed to high levels of reactive oxygen species (ROS) generated intercellularly. Recently, several anti-oxidants, including catalase, have been suggested to be cytoprotective against the development of atherosclerosis. The object of this study was to investigate whether adenovirus-mediated gene transfer of catalase in ECs can attenuate ROS production and cell apoptosis under oxidized low density lipoprotein (oxLDL) stimulation. Adenovirus-mediated gene transfer of human catalase gene (Ad-Cat) resulted in a high level of catalase overexpression in human arterial EC (HAEC), which manifested a time-dependent increase in cell viability under the exposure of oxLDL and decreased oxLDL-induced apoptosis. Phosphorylation studies of ERK1/2, JNK, and p38, three subgroups of mitogen activator protein kinase demonstrated that catalase overexpression suppressed JNK phosphorylation and increased ERK1/2 phosphorylation. NF-kappaB and AP-1 were induced after the exposure of HAECs to oxLDL. While catalase overexpression was found to inactivate AP-1, it had no effect on NF-kappaB activity. These results provide the evidence that overexpression of catalase in ECs attenuates ROS production and cell apoptosis under oxLDL stimulation. The protective effect is mediated through the downregulation of JNK and the upregulation of ERK1/2 phosphorylation as well as AP-1 inactivation. This observation supports the feasibility of catalase gene transfer to human endothelium to protect against oxidant injury.
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PMID:Adenovirus-mediated overexpression of catalase attenuates oxLDL-induced apoptosis in human aortic endothelial cells via AP-1 and C-Jun N-terminal kinase/extracellular signal-regulated kinase mitogen-activated protein kinase pathways. 1473 55

Inflammation and dyslipidaemia both play important roles in the development of glomerular atherosclerosis in renal diseases. We have demonstrated that inflammatory mediators induced Scr (scavenger receptor) expression and the formation of foam cells, and that AP-1 (activator protein 1)/ets were necessary transcriptional factors for Scr induction in HMCs (human kidney mesangial cells). Most cells are protected from excessive native LDL (low-density lipoprotein) accumulation by tight feedback regulation of the LDLr (LDL receptor). However, we observed that HMCs formed foam cells via the LDLr pathway when incubated with IL-1beta (interleukin-1beta; 5 ng/ml) and unmodified LDL (200 microg/ml), suggesting that inflammatory mediators may disrupt the cholesterol-mediated feedback regulation. This feedback involves cholesterol-mediated down-regulation of LDLr controlled by SCAP [SREBP (sterol responsive element-binding protein) cleavage-activating protein]. We have also demonstrated that both tumour necrosis factor alpha and IL-1beta increased nuclear SREBP-1 levels by increasing SCAP mRNA expression, even in the presence of a high concentration of LDL. Since intracellular lipid content is governed by both influx and efflux mechanisms, we set out to examine the impact of inflammatory cytokines on cholesterol efflux, a process mediated by the protein ABCA1 (ATP binding cassette A1). IL-1beta inhibited [(3)H]cholesterol efflux from HMCs by inhibition of the peroxisome-proliferator-activated receptor/LXR (liver X receptor)/ABCA1 pathway. Taken together, our results suggest that inflammatory mediators increase lipid accumulation in HMCs not only by promoting increased lipoprotein uptake by Scr and LDLr, but also by inhibiting ABCA1-mediated cholesterol efflux to high-density lipoprotein.
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PMID:Regulation of lipoprotein trafficking in the kidney: role of inflammatory mediators and transcription factors. 1474 20

It has been widely shown that many plant-derived compounds present significant anti-inflammatory effects. For this reason, they represent potential molecules for the development of new drugs, especially designed for the treatment and/or control of chronic inflammatory states such as rheumatism, asthma, inflammatory bowel diseases, atherosclerosis, etc. This review focuses on the naturally-occurring compounds with anti-inflammatory properties and attempts to correlate their actions with the modulation of cytokines and associated intracellular signalling pathways; it continues the review published in the November, 2003 issue of Planta Medica. Abbreviations. AP-1:activator protein-1 CCR1:chemokine receptor 1 CINC-1:cytokine-induced neutrophil chemoattractant 1 COX:cyclooxygenase EGCG:(-)-epigallocatechin gallate ELAM-1:endothelial-leukocyte adhesion molecule-1 ERK:extracellular signal-regulated kinase GRO:growth-related oncogene HUVEC:human umbilical vein endothelial cells ICAM-1:intercellular adhesion molecule-1 IFN:interferon IL:interleukin iNOS:inducible nitric oxide synthase IRA:the natural interleukin receptor activation JAK:janus kinase JNK:c-Jun NH2-terminal kinase LPS:lipopolysaccharide MAPK:mitogen-activated protein kinases MCP:monocyte chemotactic protein MHC:major histocompatibility complex MIP:macrophage inflammatory protein MMP:matrix metalloproteinases MPO:myeloperoxidase NF-kappaBnuclear factor kappa B NO:nitric oxide PAF:platelet aggregation factor PGEE:prostaglandin PK:protein kinase PMA/TPA:phorbol myristate acetate RANTES:regulated upon activation normal T-cell expressed and secreted TGF-beta:transforming growth factor-beta TNFalpha:tumour necrosis factor VCAM-1:vascular cell adhesion molecule-1
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PMID:Anti-inflammatory compounds of plant origin. Part II. modulation of pro-inflammatory cytokines, chemokines and adhesion molecules. 1499 84

Human innate immunity can respond to diverse microbial products, as well as other substances such as heat shock proteins, taxol, and unsaturated fatty acids. Mediated largely by a family of Toll-like-receptors (TLR) and associated intracellular downstream signaling molecules, human innate immune response serves multiple functions ranging from providing the first line of defense to coordinating cellular growth as well as other cellular functions. To date, about 10 distinct human TLR receptors have been identified in the human genome. Biochemical studies and genetic analyses using transgenic mice have revealed specific ligands for several TLR receptors. TLR intracellular domains could then specifically recruit several adaptor proteins including MyD88, TIRAP/MAL, TRIF, and TOLLIP. These adaptor proteins subsequently associate with a family of interleukin-1 receptor-associated kinases (IRAK1, 2, M, and 4). Recruitments of numerous downstream signaling proteins lead to activation of a range of transcription factors such as NF kappa B, AP-1, and IRFs, which are responsible for specific gene transcriptions. Human innate immunity is manifested in diverse cells and tissues. Well-coordinated innate immunity signaling enables human cells and tissues to properly respond to various substances. Improper regulations of such event have been shown to cause various diseases including asthma, atherosclerosis, and cancer. TLR receptors as well as other intracellular signaling proteins can potentially serve as therapeutic targets for numerous human diseases. This review will discuss at the molecular level, regulation of innate immunity signaling as well as its intricate connection with human diseases.
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PMID:Regulation of innate immunity signaling and its connection with human diseases. 1503 44

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