Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.10 (IKK)
 4,900 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mononuclear phagocytes play a major role in immune and inflammatory responses. Bacterial lipopolysaccharide (LPS) induces monocytes to express a variety of genes by activating the NF-kappaB/Rel transcription factor family. Recently, we have reported that the tumor necrosis factor and interleukin 1 signaling pathways activate two kinases, IKK1 and IKK2. Phosphorylation of the IkappaB cytoplasmic inhibitors, IkappaBalpha, IkappaBbeta, and IkappaBepsilon, by these kinases triggers proteolytic degradation and the release of NF-kappaB/Rel proteins into the nucleus. At present, the role of the IKKs in LPS signaling has not been investigated. Here, we report that LPS induces IKK activity in human monocytes and THP-1 monocytic cells. The kinetics of activation of kinase activity in monocytic cells are relatively slow with maximal activity observed at 60 min, which coincides with the degradation of IkappaBs and the nuclear translocation of NF-kappaB. In transfection experiments, overexpression of wild type IKK1, a dominant negative mutant IKK1 (K44M), or wild type IKK2 did not affect LPS-induced kappaB-dependent transcription in monocytic cells. In contrast, a dominant negative mutant of IKK2 inhibited LPS induction of kappaB-dependent transcription in a dose-dependent manner. These results indicate that LPS induction of kappaB-dependent gene expression in human monocytic cells requires activation of IKK2.
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PMID:Role of IKK1 and IKK2 in lipopolysaccharide signaling in human monocytic cells. 980 6

Endothelial activation and monocyte adhesion are initiating steps in atherogenesis thought to be caused in part by oxidative stress. The metabolic thiol antioxidant alpha-lipoic acid has been suggested to be of therapeutic value in pathologies associated with redox imbalances. We investigated the role of (R)-alpha-lipoic acid (LA) vs. glutathione and ascorbic acid in tumor necrosis factor alpha (TNF-alpha) -induced adhesion molecule expression and nuclear factor kappaB (NF-kappaB) signaling in human aortic endothelial cells (HAEC). Preincubation of HAEC for 48 h with LA (0.05-1 mmol/l) dose-dependently inhibited TNF-alpha (10 U/ml) -induced adhesion of human monocytic THP-1 cells, as well as mRNA and protein expression of E-selectin, vascular cell adhesion molecule 1 and intercellular adhesion molecule 1. LA also strongly inhibited TNF-alpha-induced mRNA expression of monocyte chemoattractant protein-1 but did not affect expression of TNF-alpha receptor 1. Furthermore, LA dose-dependently inhibited TNF-alpha-induced IkappaB kinase activation, subsequent degradation of IkappaB, the cytoplasmic NF-kappaB inhibitor, and nuclear translocation of NF-kappaB. In contrast, TNF-alpha-induced NF-kappaB activation and adhesion molecule expression were not affected by ascorbic acid or by manipulating cellular glutathione status with l-2-oxo-4-thiazolidinecarboxylic acid, N-acetyl-l-cysteine, or d,l-buthionine-S,R-sulfoximine. Our data show that clinically relevant concentrations of LA, but neither vitamin C nor glutathione, inhibit adhesion molecule expression in HAEC and monocyte adhesion by inhibiting the IkappaB/NF-kappaB signaling pathway at the level, or upstream, of IkappaB kinase.
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PMID:Alpha-lipoic acid inhibits TNF-alpha-induced NF-kappaB activation and adhesion molecule expression in human aortic endothelial cells. 1168 67

Neutrophil-dependent inflammation dependent on monosodium urate (MSU) crystal-induced IL-8 expression occurs in gout. MSU crystals activate phagocyte Src family tyrosine kinases and the serine/threonine kinase p70s6k. Thus, using monocytic THP-1 cells, we assessed the potential for Src family kinases and p70s6k to mediate MSU-induced IL-8 expression. MSU crystals induced phosphorylation of p70s6k and the Src kinases c-Src, Lyn, Hck, and Fyn. IL-8 expression was attenuated more by the Src kinase inhibitor PP1 than by the p70s6k inhibitor rapamycin. PP1 inhibited crystal-induced phosphorylation of ERK1/2 and IkappaBalpha and suppressed IkappaB kinase (IKK) activation and NF-kappaB binding to the IL-8 promoter, signals that mediate MSU-induced IL-8 expression. Transfection of the native Src inhibitor, C-terminal Src kinase (Csk), also suppressed crystal-induced c-Src, ERK1/2, and IkappaBalpha phosphorylation and IL-8 expression. We conclude that Src family tyrosine kinase signaling plays a significant role in MSU crystal-induced IL-8 expression via stimulation of ERK1/2 pathway and NF-kappaB activation.
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PMID:Src family protein tyrosine kinase signaling mediates monosodium urate crystal-induced IL-8 expression by monocytic THP-1 cells. 1173 59

Toll-like receptor 2 (TLR2)-mediated cell activation induced by commercial preparations of LPS was recently shown to arise from impurities whose identities are not known. In this work, we determined the molecules responsible for TLR2-mediated cell activation in LPS derived from Escherichia coli K-12 strain LCD25. When LCD25 LPS was phenol extracted, two proteins capable of TLR2-mediated cell activation were purified and identified as E. coli lipoproteins. We cloned, expressed, and purified these two lipoproteins, Lip19 and Lip12. Lip19 or Lip12 activated TNF-alpha production from RAW264.7 and THP-1 cells in a TLR2-dependent manner. However, neither Lip19 nor Lip12 activated HUVECs, which lack endogenous TLR2. Additionally, IkappaB kinase beta and c-Jun N-terminal kinase 1 activation in THP-1 cells induced by Lip19 or Lip12 was observed. TLR2 activation by Lip19 and Lip12 in HEK293 cells was blocked by inhibitory anti-TLR2 mAbs. The unlipidated mutants, Lip19-C19S and Lip12-C21S, in which the NH(2)-terminal cysteine was substituted by serine, lost their ability to activate TLR2-transfected HEK 293 cells. Taken together, these results demonstrate that two lipoproteins constitute the major contaminants responsible for TLR2-mediated cell activation in E. coli LCD25 LPS.
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PMID:Two lipoproteins extracted from Escherichia coli K-12 LCD25 lipopolysaccharide are the major components responsible for Toll-like receptor 2-mediated signaling. 1193 58

The signal-inducible phosphorylation of serines 32 and 36 of I kappa B alpha is critical in regulating the subsequent ubiquitination and proteolysis of I kappa B alpha, which then releases NF-kappa B to promote gene transcription. The multisubunit I kappa B kinase responsible for this phosphorylation contains two catalytic subunits, termed I kappa B kinase (IKK)-1 and IKK-2. BMS-345541 (4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline) was identified as a selective inhibitor of the catalytic subunits of IKK (IKK-2 IC(50) = 0.3 microm, IKK-1 IC(50) = 4 microm). The compound failed to inhibit a panel of 15 other kinases and selectively inhibited the stimulated phosphorylation of I kappa B alpha in cells (IC(50) = 4 microm) while failing to affect c-Jun and STAT3 phosphorylation, as well as mitogen-activated protein kinase-activated protein kinase 2 activation in cells. Consistent with the role of IKK/NF-kappa B in the regulation of cytokine transcription, BMS-345541 inhibited lipopolysaccharide-stimulated tumor necrosis factor alpha, interleukin-1 beta, interleukin-8, and interleukin-6 in THP-1 cells with IC(50) values in the 1- to 5-microm range. Although a Dixon plot of the inhibition of IKK-2 by BMS-345541 showed a non-linear relationship indicating non-Michaelis-Menten kinetic binding, the use of multiple inhibition analyses indicated that BMS-345541 binds in a mutually exclusive manner with respect to a peptide inhibitor corresponding to amino acids 26-42 of I kappa B alpha with Ser-32 and Ser-36 changed to aspartates and in a non-mutually exclusive manner with respect to ADP. The opposite results were obtained when studying the binding to IKK-1. A binding model is proposed in which BMS-345541 binds to similar allosteric sites on IKK-1 and IKK-2, which then affects the active sites of the subunits differently. BMS-345541 was also shown to have excellent pharmacokinetics in mice, and peroral administration showed the compound to dose-dependently inhibit the production of serum tumor necrosis factor alpha following intraperitoneal challenge with lipopolysaccharide. Thus, the compound is effective against NF-kappa B activation in mice and represents an important tool for investigating the role of IKK in disease models.
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PMID:BMS-345541 is a highly selective inhibitor of I kappa B kinase that binds at an allosteric site of the enzyme and blocks NF-kappa B-dependent transcription in mice. 1240 72

The transcription factor NF-kappaB is responsible for regulating genes that can profoundly impact cell proliferation, apoptosis, inflammation, and immune responses. The NF-kappaB inhibitor IkappaBalpha is rapidly degraded and then re-synthesized after an NF-kappaB stimulus. We have found that the re-synthesis of IkappaBalpha in a human colon-derived cell line (HT-29) includes the post-translational stabilization of newly synthesized IkappaBalpha. The TNF-alpha-induced stabilization of newly synthesized IkappaBalpha involves the C-terminal PEST region of the protein: N-terminal deletion mutants (lacking the IkappaB kinase phosphorylation sites) were readily stabilized by TNF-alpha, whereas deletion of the C-terminus resulted in a constitutively stable protein. The role of the C-terminus in stabilization was further supported by the finding that fusion of the IkappaBalpha C-terminus to GFP generated a protein that could also be stabilized by TNF-alpha. The p38 mitogen-activated protein (MAP) kinase inhibitor SB203580 prevented stabilization of IkappaBalpha and delayed the re-emergence of IkappaBalpha following TNF-alpha-induced degradation. The IkappaBalpha stabilization pathway could prevent sequential rounds of IkappaBalpha degradation without preventing IkappaBalpha phosphorylation. Analysis of two other cell lines (SW480 and THP-1) revealed similarities and cell-specific differences in the regulation of IkappaBalpha stabilization. We propose that cytokine stabilization of newly synthesized IkappaBalpha in some cell types is a critical homeostatic mechanism that limits inflammatory gene expression.
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PMID:Induced stabilization of IkappaBalpha can facilitate its re-synthesis and prevent sequential degradation. 1270 57

CHS 828, a pyridyl cyanoguanidine, has been shown to exert a significant antitumor effect in preclinical tests in vitro and in vivo, and CHS 828 is in phase I/II clinical trials. We have investigated the effect of CHS 828 on the nuclear factor-kappa B (NF-kappa B) because of its well-known role in the control of cell division and apoptosis. CHS 828 is able to inhibit the lipopolysaccharide (LPS)-induced nuclear localization as well as the transcriptional activity of NF-kappa B in human THP-1 leukemia cells. Moreover, CHS 828 has also been shown to inhibit the LPS-induced degradation of the I kappa B alpha and I kappa B beta in THP-1 cells, leading us to identify the I kappa B kinase complex as a molecular target of CHS 828. The IKK activity is inhibited by CHS 828 with an IC(50) of 8 nM. The inhibition of the IKK activity by different CHS 828 analogues correlates well with the inhibition of NYH small cell lung cancer cell proliferation in vitro and in vivo. Moreover, the inhibition of NF-kappa B transcriptional activity in different cancer cell lines by CHS 828 correlates to some extent with the reduction by CHS 828 of the size of the corresponding xenografts. Activation of NF-kappa B has been shown to induce expression of antiapoptotic proteins, and cancer cells have been shown to have high levels of constitutively active NF-kappa B. Therefore, we hypothesize that the anticancer activity of CHS 828 is due to inhibition of the IKK activity by which the antiapoptotic protection of NF-kappa B is removed, leading to the promotion of apoptosis.
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PMID:Anticancer agent CHS 828 suppresses nuclear factor-kappa B activity in cancer cells through downregulation of IKK activity. 1519 71

Decoy receptor 3 (DcR3), a soluble receptor for FasL, LIGHT and TL1A, is highly expressed in cancer cells. We show that pretreatment of HUVECs with DcR3 enhances the adhesion of THP-1 and U937 cells and primary monocytes. A similar stimulatory effect of DcR3 on THP-1 adhesion was also observed in human microvascular endothelial cells (HMVECs). Flow cytometry and ELISA showed that DcR3-treated HUVECs exhibited significant increases in ICAM-1 and VCAM-1 expression. We also demonstrate the ability of DcR3 to stimulate the secretion of IL-8 by HUVECs. RT-PCR and reporter assays revealed that the expression of adhesion molecules and IL-8 are regulated at the level of gene transcription. Experiments with pyrrolidine dithiocarbamate indicated the involvement of an NF-kappaB signaling pathway. DcR3 was found to induce IkappaB kinase activation, IkappaB degradation, p65 nuclear translocation, and NF-kappaB DNA-binding activity. The enhancement by DcR3 of cell adhesion to HUVECs was not mimicked by the TL1A-Ab, which has been shown in our previous work to be a neutralizing Ab against TL1A, thereby inducing HUVECs angiogenesis. Moreover, DcR3-induced cell adhesion could be detected in human aortic endothelial cells (ECs) in which TL1A expression is lacking. Together, our data demonstrate that DcR3 increases monocyte adhesion to ECs via NF-kappaB activation, leading to the transcriptional up-regulation of adhesion molecules and IL-8 in ECs. This novel action appears not to be due to TL1A neutralization, but occurs through an as yet undefined target(s). This study implicates DcR3 in the relationship between inflammation and cancer development.
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PMID:Decoy receptor 3 increases monocyte adhesion to endothelial cells via NF-kappa B-dependent up-regulation of intercellular adhesion molecule-1, VCAM-1, and IL-8 expression. 1566 28

Reactive oxygen species, such as superoxide anion (O2-) and hydrogen peroxide (H2O2), may act as second messengers of intracellular signaling and play a key role in the pathogenesis of atherosclerosis. The nuclear factor kappaB (NF-kappa B) is a redox-sensitive transcription factor that is involved in this process. The aim of the present study was to investigate the molecular mechanisms of action of statins on cultured vascular smooth muscle cells (VSMC) and monocytic cells (THP-1) under oxidative stress. In THP-1 and cultured VSMC, O2- caused an increase in NF-kappa B activation (P < 0.05) that was correlated with inhibitory I kappa B-alpha degradation. Atorvastatin or simvastatin decreased NF-kappa B activation induced by oxidative stress by around 50% in both cell types and was correlated with the I kappa B-alpha levels. In monocytes, O2- increased I kappa B kinase (IKK)-1 and IKK-2 activity (P < 0.05) and p38 and p42/44 activation and phosphorylation, which was reduced by statins. PD 98059 (p42/44 inhibitor) and SB20358 (p38 inhibitor) decreased NF-kappa B binding activity and prevented I kappa B-alpha degradation. However, we only observed a reduction in IKK-1 and IKK-2 activity with PD98059. Statins diminish NF-kappa B activation elicited by oxidative stress through the inhibition of IKK-1/-2, p38, and p42/44 activation. These data may help to further understand the molecular mechanisms of statins in cardiovascular disease.
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PMID:HMG-CoA reductase inhibitors reduce I kappa B kinase activity induced by oxidative stress in monocytes and vascular smooth muscle cells. 1582 43

The interferon-inducible, double-stranded (ds)RNA-dependent protein kinase (PKR) plays a major role in antiviral defense mechanisms where it down-regulates translation via phosphorylation of eukaryotic translation initiation factor 2alpha. PKR is also involved in the activation of nuclear factor kappaB (NFkappaB) through activation of the IkappaB kinase complex. Activation of PKR can occur in the absence of dsRNA and in such case is controlled by intracellular regulators like the PKR-activating protein (PACT), the PKR inhibitor p58(IPK), or heat-shock proteins (Hsp). These regulators are activated by stress stimuli, supporting a role for PKR in response to stress; however the final outcome of PKR activation in stress situations is unclear. We present here evidence that expression and activation of PKR contributes to an increased cellular resistance to mercury cytotoxicity. In two cell lines constitutively expressing PKR (THP-1 and Molt-3), treatment with the PKR inhibitor 2-aminopurine increases their sensitivity to mercury. In contrast, Ramos cells, which do not constitutively express PKR, present an increased resistance to mercury when PKR expression is induced by polyIC or interferon-beta treatment. This protective effect is inhibited by 2-aminopurine. We also show that exposure of Ramos cells to mercury leads to the induction of Hsp70. Treatment of cells with Hsp70 or NFkappaB inhibitors suppresses the PKR-dependent protection. We propose a model where PKR, modulated by Hsp70, activates a NFkappaB-mediated protective pathway. Because the cytotoxicity of mercury is primarily due to the generation of reactive oxygen species, our results suggest a more general function of PKR in the mechanisms of cellular response to oxidative stress.
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PMID:Double-stranded RNA-dependent protein kinase (PKR) is a stress-responsive kinase that induces NFkappaB-mediated resistance against mercury cytotoxicity. 1632 19


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