Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the lesions of atherosclerosis, vascular smooth muscle cells (SMC) display many functions characteristic of cytokine activation that likely contribute importantly to ongoing inflammation during human atherogenesis. The transcription factor nuclear factor kappa-B (NFkappaB) often mediates the effects of cytokines on target cells, but the identity of Rel family members important in human SMC activation remains uncertain. In vitro, human SMC express multiple Rel family members. Of these, dimers of p65 and p50, but not a putative SMC-Rel, comprise basal and inducible NFkappaB binding activities. SMC express two inhibitor proteins IkappaBbeta and IkappaBalpha. Interleukin-1beta stimulation caused transient loss of IkappaBalpha and a sustained decrease of IkappaBbeta that correlated with increased and persistent levels of p65/p50 protein and binding activity in the nucleus. SMC cultured under serum-free conditions displayed little NFkappaB activity, but addition of serum or platelet-derived growth factor did activate NFkappaB. In situ analyses showed no evidence for basal NFkappaB activity in SMC in vivo as nonatherosclerotic arteries did not contain nuclear p65 or p50 protein. However, the nuclei of intimal SMC within human atheroma did contain both Rel proteins. We conclude that (i) dimers of p65 and p50, but not SMC-Rel, comprise NFkappaB complexes in human SMC; (ii) stimulatory components in serum activate NFkappaB and likely account for previously reported "constitutive" NFkappaB activity in cultured SMC; and (iii) exposure to inflammatory cytokines may produce prolonged NFkappaB activation in SMC because of sustained decreases in the inhibitory subunit IkappaB-beta.
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PMID:The nuclear factor kappa-B signaling pathway participates in dysregulation of vascular smooth muscle cells in vitro and in human atherosclerosis. 918 79

Apoptosis is important in normal development as well as in diseases such as atherosclerosis. However, the regulation of apoptosis is still not completely understood. We now show that the transcription factor nuclear factor-kappaB (NF-kappaB) controls the induction of apoptosis in human and rat vascular smooth muscle cells (SMCs). SMCs in high-density culture exhibited a high NF-kappaB activity and were insensitive to induction of apoptosis. Inhibition of NF-kappaB by adenovirus-mediated overexpression of its inhibitor IkappaBalpha caused a marked increase in cell death at low but not high cell density. Elevating endogenous IkappaBalpha levels by inhibiting its degradation with proteasomal inhibitors resulted in induction of apoptosis in low-density SMCs, as detected by increased binding of annexin V, reduced mitochondrial membrane potential, and increased hypodiploid DNA. In high-density cultures, protection against apoptosis was associated with the expression of inhibitor of apoptosis protein-1 (IAP-1). Transfer of IkappaBalpha reduced human IAP-1 mRNA levels, which suggested that IAP-1 is transcriptionally regulated by NF-kappaB. This was confirmed through identification of a motif with NF-kappaB-like binding activity in the human IAP-1 promoter region. Moreover, antisense inhibition of IAP-1 sensitized high-density SMCs to the induction of cell death. Together, our data imply that SMCs at high density are protected by an antiapoptotic mechanism that involves increased expression of NF-kappaB and IAP-1. Interference with pathways that control the susceptibility to programmed cell death may be helpful in the treatment of diseases where dysregulation of apoptosis is involved, eg, atherosclerosis and restenosis.
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PMID:Nuclear factor-kappa B regulates induction of apoptosis and inhibitor of apoptosis protein-1 expression in vascular smooth muscle cells. 1018 54

Atherogenesis is a multifactorial chronic inflammatory disease in which low plasma levels of HDLs are a strong predictor of the condition. Although the mechanism of protection by HDLs is not precisely known, HDLs have been shown to influence many of the events involved in the development of atherosclerosis. Previously we have shown that HDLs inhibited the cytokine-induced expression of adhesion molecules (E-selectin, VCAM-1, and ICAM-1) by endothelial cells (ECs). As the complete transcriptional regulation of all 3 genes requires the NF-kappaB family of transcription factors, we examined the effect of HDLs on activation of NF-kappaB. We also investigated the effect of HDLs on 2 other cytokine-induced genes, granulocyte-macrophage colony-stimulating factor (GM-CSF) and cyclooxygenase (Cox-2; prostaglandin H2 synthase, EC 0.1.14.99.1). E-selectin expression in response to tumor necrosis factor-alpha (TNFalpha) was, as expected, inhibited in ECs that had been preincubated with HDLs. However, the level of secretion of GM-CSF in the same cultures was no different from control. In a similar manner, although HDLs had no effect on steady-state mRNA levels of GM-CSF, the levels of E-selectin were significantly inhibited by HDLs. In transient cotransfection experiments we found that HDLs inhibited the cytokine-induced expression of a reporter gene driven by the E-selectin proximal promoter (-383 to 80) but had no effect on the expression of a reporter gene driven under the control of the proximal promoter of GM-CSF (-627 to 28). As would be predicted from this differential response, HDLs did not influence the nuclear translocation or DNA binding of NF-kappaB, or alter the kinetics of degradation and resynthesis of the inhibitory protein IkappaBalpha. We found that HDLs synergized with cytokine to enhance the expression of Cox-2 and induce the synthesis of its main EC product, prostacyclin (PGI2), a potent inhibitor of platelet and leukocyte functions. In conclusion, HDL induces an antiinflammatory phenotype in cytokine-induced ECs, synergizing with cytokine to induce elevation of Cox-2 in addition to inhibiting adhesion molecule expression. Our studies show that these differential effects are mediated in a manner that is likely to be independent of NF-kappaB per se.
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PMID:High-density lipoproteins differentially modulate cytokine-induced expression of E-selectin and cyclooxygenase-2. 1019 17

Flavonoids are a group of naturally-occurring phenolic compounds in the plant kingdom, and many flavonoids are found with vascular protective properties. Nevertheless how the protective response is exerted by flavonoids is not well characterized. In view of the nuclear factor-kappaB (NFkappaB) may play a central role in the initiation of atherosclerosis, prevention of the activation of NFkappaB represents an important role in protecting vascular injury. In this study, the effects of flavonoids on NFkappaB/inhibitor-kappaB (IkappaB) system in ECV304 cells activated with tumor necrosis factor-alpha (TNFalpha) were examined. We investigated the inhibitory action of six flavonoids on IkappaB kinase (IKK) activity, an enzyme recently found to phosphorylate critical serine residues of IkappaB for degradation. Of six flavonoids tested, myricetin was found to strongly inhibit IKK kinase activity, and prevent the degradation of IkappaBalpha and IkappaBbeta in activated endothelial cells. Furthermore, myricetin was also found to inhibit NFkappaB activity correlated with suppression of monocyte adhesion to ECV304 cells. Therefore we conclude that flavonoids may be of therapeutic value for vascular disease through down regulation of NFkappaB/IkappaB system.
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PMID:Suppression of TNFalpha-mediated NFkappaB activity by myricetin and other flavonoids through downregulating the activity of IKK in ECV304 cells. 1044 Sep 30

Increased oxidative stress has been reported in vivo in the diabetic state via the production of reactive oxygen species (ROS). Such stress is bound to play a key role on activation of circulating monocytes, leading to the accelerated atherosclerosis observed in diabetics. However the exact molecular mechanisms of monocyte activation by high glucose is currently unclear. Here, we demonstrate that chronic high glucose (CHG) causes a dramatic increase in the release of the inflammatory cytokine tumor necrosis factor alpha (TNFalpha), at least in part through enhanced TNFalpha mRNA transcription, mediated by ROS via activation of transcription factors nuclear factor kappaB (NF-kappaB) and activating protein-1 (AP-1). TNFalpha accumulation in the conditioned media was increased 10-fold and mRNA levels were increased 11.5-fold by CHG. The following observations supported that both NF-kappaB and AP-1 mediated enhanced TNFalpha transcription by CHG: 1) A 295-base pair fragment of the proximal TNFalpha promoter containing NF-kappaB and AP-1 sites reproduced the effects of CHG on TNFalpha transcription in a luciferase reporter assay, 2) mutational analyses of both NF-kappaB and the AP-1 sites abrogated 90% of the luciferase activity, 3) gel-shift analysis using the binding sites showed activation of NF-kappaB and AP-1 in CHG nuclear extracts, and 4) Western blot analyses demonstrated elevated nuclear levels of p65 and p50 and decreased cytosolic levels of IkappaBalpha in CHG-treated monocytes. That ROS acted as a key intermediate in the CHG pathway was supported by the following evidence: 1) increased superoxide levels similar to those observed with PMA or TNFalpha, 2) increased phosphorylation of stress-responsive mitogen-activated protein kinases p38 and JNK-1, 3) counteraction of the effects of CHG on TNFalpha production, the 295TNFluc reporter activity, activation of NF-kappaB, and repression of IkappaBalpha by antioxidants and p38 mitogen-activated protein kinase inhibitors. The study suggests that ROS function as key components in the regulatory pathway progressing from elevated glucose to monocyte activation.
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PMID:Molecular mechanisms of tumor necrosis factor alpha gene expression in monocytic cells via hyperglycemia-induced oxidant stress-dependent and -independent pathways. 1083 98

Chronic inflammation is a hallmark of degenerative diseases such as atherosclerosis. Peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily, which are expressed in the cells of the atherosclerosic lesion. PPARalpha ligands have been reported to exert anti-inflammatory activities in different cell types by antagonizing the transcriptional activity of NF-kappaB. In the present study, the influence of PPARalpha activators on the NF-kappaB signaling pathway was investigated. Our results show that fibrates, synthetic PPARalpha activators, induced the expression of the inhibitory protein IkappaBalpha in human aortic smooth muscle cells as well as in primary human hepatocytes, whereas neither IkappaB-kinase activity nor the degradation rate of IkappaBalpha were affected. Using PPARalpha-null mice, we demonstrated that fibrates induced IkappaBalpha in liver in vivo and that this action required PPARalpha. Furthermore, fibrate treatment induced IkappaBalpha protein expression in the cytoplasm and also enhanced IL-1beta-induced accumulation of IkappaBalpha protein in the nucleus. These actions of fibrates on IkappaBalpha expression were accompanied by a decrease in NF-kappaB DNA binding activity as demonstrated by electrophoretic mobility shift assays. Taken together, these data provide an additional molecular mechanism for the anti-inflammatory activity of PPARalpha agonists and reinforce their potential use in the treatment of inflammatory diseases.
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PMID:Induction of IkappaBalpha expression as a mechanism contributing to the anti-inflammatory activities of peroxisome proliferator-activated receptor-alpha activators. 1098 Jan 95

Dysregulation of apoptosis is one of the likely underlying mechanisms of neointimal thickening, a disorder in which proinflammatory cytokines may influence the function of vascular smooth muscle cells (VSMCs) and contribute to atherogenesis. One of these cytokines, tumor necrosis factor-alpha (TNF-alpha), induces 2 possibly conflicting pathways, 1 leading to the activation of nuclear factor-kappaB (NF-kappaB) and the other leading to caspase-mediated apoptosis. We investigated whether specific inhibition of NF-kappaB affects TNF-alpha-dependent apoptosis in human VSMCs. To inhibit NF-kappaB activation specifically, we constructed a recombinant adenovirus vector expressing a truncated form of the inhibitor protein IkappaBalpha (AdexIkappaBDeltaN) that lacks the phosphorylation sites essential for activation of NF-kappaB. The IkappaBDeltaN was overexpressed by adenoviral infection and was resistant to stimulus-dependent degradation. Electromobility gel shift and luciferase assays demonstrated that overexpression of IkappaBDeltaN inhibited NF-kappaB activation induced by TNF-alpha or interleukin-1beta (IL-1beta). In cells overexpressing IkappaBDeltaN, TNF-alpha dramatically induced apoptosis, whereas IL-1beta had no effect. The induction was suppressed by treatment with a selective inhibitor of the caspase-3 family, Z-DEVD-fmk, and the overexpression of IkappaBDeltaN induced TNF-alpha-mediated caspase-3 and caspase-2 activity. These results indicate that overexpression of IkappaBDeltaN induces TNF-alpha-dependent apoptosis by efficient and specific suppression of NF-kappaB and upregulation of caspase-3 and caspase-2 activity in human VSMCs. Our findings suggest that adenovirus-mediated IkappaBDeltaN gene transfer may be useful in the treatment of disorders associated with inflammatory conditions, such as the response to vascular injury and atherosclerosis.
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PMID:Overexpression of truncated IkappaBalpha induces TNF-alpha-dependent apoptosis in human vascular smooth muscle cells. 1103 Dec 4

Tissue factor (TF), the primary initiator of blood coagulation with structural homology to the cytokine receptor family, has been implicated in various vascular processes including metastasis, angiogenesis, and atherosclerosis. Within the vasculature, monocytes and endothelial cells (EC) can be activated to synthesize TF depending on the induction of NF-kappaB. Despite the undisputed value of cyclosporin A (CsA) as an immunosuppressant, problems have emerged due to induction of vascular changes by a poorly understood mechanism. We demonstrate that CsA has opposite effects on TF gene expression, inhibiting NF-kappaB-mediated TF gene transcription in monocytes but enhancing it in EC. To test whether CsA binding proteins (cyclophilins) can mediate these CsA effects we used a nonimmunosuppressant analog of CsA that binds to cyclophilins but does not inhibit the Ca2+/calmodulin-dependent phosphatase calcineurin (Cn). This drug lacked regulatory function for NF-kappaB and TF expression suggesting that Cn is responsible for the inverse gene regulation. The key function of Cn was supported by experiments demonstrating that other phosphatase inhibitors also either positively or negatively regulated NF-kappaB in monocytes and EC. Calcineurin was demonstrated to regulate NF-kappaB activation at the level of IkappaBalpha degradation, because agonist-induced phosphorylation and subsequent degradation of IkappaBalpha is prevented by Cn inhibitors in monocytes but enhanced in EC. These data identify Cn as an opposite regulator in generating transcriptionally active NF-kappaB, and they confirm the presumption that the ability of Cn to participate in NF-kappaB transactivation is not T cell specific.
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PMID:Opposite regulation of tissue factor expression by calcineurin in monocytes and endothelial cells. 1139 Apr 56

IL-8 is an important mediator of leukocyte trafficking and activation, participating in tumor angiogenesis, inflammatory processes and coronary atherosclerosis. Under flow conditions IL-8, in conjunction with MCP-1, triggers the firm adhesion of monocytes to the vascular endothelium. While previous studies have suggested the requirement of NF-kappaB for IL-8 secretion by endothelial cells, we investigated the possibility of IL-8 transactivation under conditions of NF-kappaB suppression. Inhibition of the proteasome by MG-132 or lactacystin completely blocked TNF-alpha-induced IkappaBalpha degradation as well as NF-kappaB activity in human arterial endothelial cells. Surprisingly, basal secretion of IL-8 protein was eight- to tenfold induced by proteasome inhibitors, while MCP-1 expression was, as expected, completely down-regulated. IL-8 was up-regulated at the transcriptional level, and promoter studies proved a more than ninefold induction of transcription factor AP-1 activity to be the cause of increased IL-8 transcription. Mutation of the AP-1 binding site in an IL-8 promoter construct completely abrogated this effect, while mutation of the NF-kappaB motif did not influence IL-8 transactivation by proteasome inhibitors. With DNA binding assays we found a seven- to eightfold induction of phosphorylated c-Jun and hence JNK kinase activity under MG-132 treatment. Induction of JNK kinase appeared independent of the cell type, even in tumor cell lines not responding to proteasome inhibitors. Since neither inactivation of p53 in wild-type p53 cells nor reintroduction of functional p53 into p53(-/-) cells affected MG-132-inducible IL-8 secretion, a direct influence of p53 on IL-8 regulation could be excluded. These results show that proteasome inhibitors can not only lead to functional AP-1 induction by enhanced c-Jun phosphorylation, but also transactivate the IL-8 gene in human endothelial cells despite complete suppression of NF-kappaB activity.
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PMID:Proteasome inhibition leads to NF-kappaB-independent IL-8 transactivation in human endothelial cells through induction of AP-1. 1220 33

The activation of Nuclear Factor kappa B (NF-kappaB) in vascular endothelial cells, in response to biochemical or biomechanical stimuli, is associated with vascular pathologies such as atherosclerosis. The present manuscript studies the ability of the natural antioxidant-pomegranate wine (PW), to inhibit tumor necrosis factor alpha (TNF-alpha) or shear stress-mediated-NF-kappaB activation in vascular endothelial cells and compares it to that of red wine (RW) and N-acetyl cysteine (NAC). PW and RW act as potent antioxidants in vascular endothelial cells, inhibiting the oxidation of 2',7'-dichloroflurescin diacetate in TNF-alpha treated cells. PW (as well as RW and NAC) acted as potent inhibitors of NF-kappaB activation (migration into the nucleus and DNA binding activity) in vascular endothelial cells. Nevertheless, PW and NAC failed to inhibit TNF-a induced serine 32/36 phosphorylation and IkappaBalpha degradation. Surprisingly, these antioxidants alone induced enhanced IkappaB serine phosphorylation, which was not accompanied by IkappaBalpha degradation, or NF-kappaB nuclear translocation. This phosphorylation did not involve serine 32/36. Furthermore, we show for the first time that NAC inhibited TNF-alpha mediated phosphorylation of p65 (ser536), whereas PW had no effect on this phosphorylation. Thus, natural antioxidants may serve as potent NF-kappaB inhibitors in vascular endothelial cells, yet act through unique and divergent pathways.
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PMID:A novel mechanism for the inhibition of NF-kappaB activation in vascular endothelial cells by natural antioxidants. 1236 28


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