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)

KIR2DL4 (2DL4) is a member of the killer cell Ig-like receptor (KIR) family in human NK cells. It can stimulate potent cytokine production and weak cytolytic activity in resting NK cells, but the mechanism for 2DL4-mediated signaling remains unclear. In this study we characterized the signaling pathways stimulated by 2DL4 engagement. In a human NK-like cell line, KHYG-1, cross-linking of 2DL4 activated MAPKs including JNK, ERK, and p38. Furthermore, 2DL4 cross-linking resulted in phosphorylation of IkappaB kinase beta (IKKbeta) and the phosphorylation and degradation of IkappaBalpha, which indicate activation of the classical NF-kappaB pathway. Engagement of 2DL4 was also shown to activate the transcription and translation of a variety of cytokine genes, including TNF-alpha, IFN-gamma, MIP1alpha, MIP1beta, and IL-8. Pharmacological inhibitors of JNK, MEK1/2 and p38, blocked IFN-gamma, IL-8, and MIP1alpha production, suggesting that MAPKs are regulating 2DL4-mediated cytokine production in a nonredundant manner. Activation of both p38 and ERK appear to be upstream of the stimulation of NF-kappaB. Mutation of a transmembrane arginine in 2DL4 to glycine (R/G mutant) abrogated FcepsilonRI-gamma association, as well as receptor-mediated cytolytic activity and calcium responses. Surprisingly, the R/G mutant still activated MAPKs and the NF-kappaB pathway and selectively stimulated the production of MIP1alpha, but not that of IFN-gamma or IL-8. In conclusion, we provide evidence that the activating functions of 2DL4 can be compartmentalized into two distinct structural modules: 1) through transmembrane association with FcepsilonRI-gamma; and 2) through another receptor domain independent of the transmembrane arginine.
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PMID:KIR2DL4 differentially signals downstream functions in human NK cells through distinct structural modules. 1829 14

Inhibitor of NF-kappaB (IkappaB) kinase (IKK) and c-Jun NH(2)-terminal kinase (JNK) are stress inducible kinases that critically regulate numerous physiological and pathological processes. Transient activation of the downstream transcription factors NF-kappaB and AP-1, allows for stress inducible, inflammatory and innate immune gene expression programs. However, elevated chronic activity is associated with cancer and chronic inflammatory disease. Despite its relevance to human health, little is known about the molecular mechanisms that control constitutive activity of IKK and JNK. Here, we demonstrate that the serine/threonine kinase PKN1 plays a critical role in regulating constitutive IKK/JNK activity in unstimulated cells and report on the molecular mechanism. We identify TRAF1 as a substrate of PKN1 kinase activity in vitro and in vivo, and show that this phosphorylation event is required for attenuating downstream kinase activities. Furthermore, this silencing was dependent on TNFR2. Mutagenesis of the phospho-acceptor residue in TRAF1 abrogated PKN1-dependent recruitment to TNFR2. Our results suggest a model by which the stoichiometric ratio of TRAF1 and TRAF2 heteromeric complexes associated with TNFR2 control the tonic activity of JNK and IKK. TRAF1 phosphorylation by the ubiquitously expressed kinase PKN1 thereby plays a critical role in the negative regulation of tonic activity of the two central inflammatory signaling pathways.
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PMID:Negative regulation of constitutive NF-kappaB and JNK signaling by PKN1-mediated phosphorylation of TRAF1. 1842 22

Nuclear factor-kappaB (NF-kappaB) is critically important for tumor cell survival, growth, angiogenesis, and metastasis. One of the key events in the NF-kappaB signaling is the activation of inhibitor of NF-kappaB kinase (IKK) in response to stimuli of various cytokines. We have identified 17-acetoxyjolkinolide B (17-AJB) from a traditional Chinese medicinal herb Euphorbia fischeriana Steud as a novel small-molecule inhibitor of IKK. 17-AJB effectively inhibited tumor necrosis factor-alpha-induced NF-kappaB activation and induced apoptosis of tumor cells. 17-AJB had no effect on binding of tumor necrosis factor-alpha to its receptor or on binding of NF-kappaB to DNA. It inhibited NF-kappaB nuclear translocation. Detailed analysis revealed that the direct target of 17-AJB was IKK. 17-AJB kept IKK in its phosphorylated form irreversibly. This irreversible modification of IKK inactivated its kinase activity, leading to its failure to activate NF-kappaB. The effect of 17-AJB on IKK was specific. It had no effect on other kinases such as p38, p44/42, and JNK. In addition, 17-AJB induced apoptosis in tumor cells. The effects of 17-AJB on apoptosis correlated with inhibition of expression of the NF-kappaB-regulated genes. Taken together, our data suggest that 17-AJB is a novel type NF-kappaB pathway inhibitor. Its unique interaction mechanism with IKK may render it a strong apoptosis inducer of tumor cells and a novel type anticancer drug candidate.
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PMID:17-Acetoxyjolkinolide B irreversibly inhibits IkappaB kinase and induces apoptosis of tumor cells. 1856 23

TAK1 (transforming growth factor-beta-activated kinase 1), a mitogen-activated protein kinase kinase kinase, is activated by various cytokines, including interleukin-1 (IL-1). However, the precise regulation for TAK1 activation at the molecular level is still not fully understood. Here we report that dual phosphorylation of Thr-178 and Thr-184 residues within the kinase activation loop of TAK1 is essential for TAK1-mediated NFkappaB and AP-1 activation. Once co-overexpressed with TAB1, TAK1 mutant with alanine substitution of these two residues fails to activate IKKbeta-mediated NFkappaB and JNK-mediated AP-1, whereas TAK1 mutant with replacement of these two sites with acidic residues acts like the TAK1 wild type. Consistently, TAK1 mutant with alanine substitution of these two residues severely inhibits IL-1-induced NFkappaB and AP-1 activities, whereas TAK1 mutant with replacement of these two sites with acidic residues slightly enhances IL-1-induced NFkappaB and AP-1 activities compared with the TAK1 wild-type. IL-1 induces the phosphorylation of endogenous TAK1 at Thr-178 and Thr-184. Reconstitution of TAK1-deficient mouse embryo fibroblast cells with wild-type TAK1 or a TAK1 mutant containing threonine 178 and 184 to alanine mutations revealed the importance of these two sites in IL-1-mediated IKK-NFkappaB and JNK-AP-1 activation as well as IL-1-induced IL-6 gene expression. Our finding is the first report that substitution of key serine/threonine residues with acidic residues mimics the phosphorylated state of TAK1 and renders TAK1 active during its induced activation.
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PMID:Phosphorylation of Thr-178 and Thr-184 in the TAK1 T-loop is required for interleukin (IL)-1-mediated optimal NFkappaB and AP-1 activation as well as IL-6 gene expression. 1861 12

TRAF6, a crucial adaptor molecule in innate and adaptive immunity, contains three distinct functional domains. The C-terminal TRAF domain facilitates oligomerization and sequence-specific interaction with receptors or other adaptor proteins. In conjunction with the dimeric E2 enzyme Ubc13-Uev1A, the N-terminal RING domain of TRAF6 functions as an E3 ubiquitin (Ub) ligase that facilitates its own site-specific ubiquitination through the generation of a Lys-63-linked poly-Ub chain. This modification does not cause its proteasomal degradation but rather serves as a scaffold to activate both the IKK and stress kinase pathways. Connecting the N-and C-terminal regions, the four internal zinc finger (ZF) motifs have yet to be functionally defined. In this study, we examined the role of the ZF domains in interleukin-1, lipopolysaccharide, and RANKL signaling by reconstitution of TRAF6-deficient cells with point mutations or deletions of these ZF motifs. Although ZF domains 2-4 are dispensable for activating IKK, p38, and JNK by interleukin-1 and lipopolysaccharide, the first ZF domain together with an intact RING domain of TRAF6 is essential for activating these pathways. Furthermore, TRAF6 autoubiquitination and its interaction with Ubc13 are dependent on ZF1 and an intact RING domain. Additionally, expression of TRAF6 lacking ZF2-4 in TRAF6-deficient monocytes rescues RANKL-mediated osteoclast differentiation and LPS-stimulated interleukin-6 production. These data provide evidence for the critical role of the Ub ligase activity of TRAF6, which is coordinated via the RING domain and ZF1 to supply the necessary elements in signaling by cytokines dependent upon TRAF6.
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PMID:The RING domain and first zinc finger of TRAF6 coordinate signaling by interleukin-1, lipopolysaccharide, and RANKL. 1861 13

The present study addressed the modulatory role of CC chemokine receptor 4 (CCR4) in Toll-like receptor (TLR) 9-mediated innate immunity and explored the underlying molecular mechanisms. Our results demonstrated that CCR4-deficient mice were resistant to both septic peritonitis induced by cecal ligation and puncture (CLP) and CpG DNA/D-galactosamine-induced shock. In bone marrow-derived macrophages (BMMPhi) from CLP-treated CCR4-deficient mice, TLR9-mediated pathways of MAPK/AP-1, PI3K/Akt, and IkappaB kinase (IKK)/NF-kappaB were impaired compared to wild-type (WT) cells. While TLR9 expression was not altered, the intensity of internalized CpG DNA was increased in CCR4-deficient macrophages when compared to WT macrophages. Pharmacological inhibitor studies revealed that impaired activation of JNK, PI3K/Akt, and/or IKK/NF-kappaB could be responsible for decreased proinflammatory cytokine expression in CCR4-deficient macrophages. Interestingly, the CCR4-deficient BMMPhi exhibited an alternatively activated (M2) phenotype and the impaired TLR9-mediated signal transduction responses in CCR4-deficient cells were similar to the signaling responses observed in WT BMMPhi skewed to an alternatively activated phenotype. These results indicate that macrophages deficient in CCR4 impart a regulatory influence on TLR9-mediated innate immunity.
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PMID:CC chemokine receptor 4 modulates Toll-like receptor 9-mediated innate immunity and signaling. 1862 3

Celecoxib is a specific inhibitor of cyclooxygenase 2 (COX2). While it has been used for the treatment of chronic inflammatory conditions, including rheumatoid arthritis, its detailed anti-inflammatory mechanism has not been clarified. Here, we found that Celecoxib potently inhibited TNFalpha-induced transcriptional activity and DNA binding activity of NF-kappaB; however, Celecoxib had no effect on TNFalpha-induced IKK activation and degradation of IkappaBalpha and IkappaBbeta, suggesting that it inhibited NF-kappaB activation via suppressing downstream of IKK activation and IkappaBs degradation. Interestingly, it was also found that Celecoxib abrogated TNFalpha-induced nuclear accumulation of the NF-kappaB p65 subunit. As a result, TNFalpha-induced expression of inflammatory cytokines, CXCL1/KC and CCL2/MCP-1, was clearly inhibited by Celecoxib. On the other hand, Celecoxib had no effect on the TNFalpha-induced nuclear translocation of c-jun and activation of ERK, JNK, p38 and Akt. Taken together, these data indicate that Celecoxib specifically inhibits TNFalpha-induced NF-kappaB activation at the level of its nuclear translocation. This negative regulation of NF-kappaB activation by Celecoxib might be an important mechanism leading to its anti-inflammatory activity.
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PMID:Celecoxib potently inhibits TNFalpha-induced nuclear translocation and activation of NF-kappaB. 1864 47

The nuclear receptor PPARgamma is a lipid sensor that regulates lipid metabolism through gene transcription. Inhibition of PPARgamma activity by TNF-alpha is involved in pathogenesis of insulin resistance, atherosclerosis, inflammation, and cancer cachexia. PPARgamma activity is regulated by TNF-alpha at pre-translational and post-translational levels. Activation of serine kinases including IKK, ERK, JNK, and p38 may be involved in the TNF-regulation of PPARgamma. Of the four kinases, IKK is a dominant signaling molecule in the TNF-regulation of PPARgamma. IKK acts through at least two mechanisms: inhibition of PPARgamma expression and activation of PPARgamma corepressor. In this review article, literature is reviewed with a focus on the mechanisms of PPARgamma inhibition by TNF-alpha.
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PMID:Regulation of PPARgamma function by TNF-alpha. 1865 73

Pyrrolidine dithiocarbamate (PDTC) is a metal chelator. Biologically, slight toxic affects EC50, 100+/-5.9 microM are observed when added to cultured HL-60 cells. CuCl2 at a physiological concentration (1 microM), but not FeCl2, Pb potentiated the cytotoxic effect of PDTC by 700 fold (EC50, 0.14+/-0.02 microM). Furthermore, results indicated that the PDTC/Cu complex induced an apoptotic process, evidenced by apoptotic bodies, DNA ladder and hypodiploidy cells. Additional studies showed that PDTC/Cu complex significantly decreased mitochondrial membrane potential, increased cytochrome c release, and reactive oxygen species production, and depleted reduced non-protein thiols in a time-dependent manner. Following oxidative stress, the PDTC/Cu complex sequentially activated JNK, NF-kappaB and AP-1 signaling pathways while IkappaB kinase activity was enhanced. The apoptotic process was eventually induced by caspase 3 activation and PARP degradation. The non-permeable copper-specific chelator-bathocuproine disulfonate (BCPS) and vitamin C were able to inhibit apoptosis and the elevation of intracellular Cu. Based on these findings; we conclude that PDTC/Cu complex-induced apoptosis is mediated by activation of JNK, NF-kappaB, AP-1 and caspase 3. Due to its high potency, PDTC may be useful as a therapeutic anti-cancer drug.
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PMID:Involvement of activating transcription factors JNK, NF-kappaB, and AP-1 in apoptosis induced by pyrrolidine dithiocarbamate/Cu complex. 1867 63

Cytosolic phospholipase A2 (cPLA2) plays a pivotal role in mediating agonist-induced arachidonic acid release for prostaglandin (PG) synthesis during stimulation with interleukin-1beta (IL-1beta). However, the mechanisms underlying IL-1beta-induced cPLA2 expression and PGE2 synthesis by canine tracheal smooth muscle cells (CTSMCs) have not been defined. IL-1beta induced cPLA2 protein and mRNA expression, PGE2 production, and phosphorylation of p42/p44 MAPK, p38 MAPK (ATF2), and JNK (c-Jun) in a time- and concentration-dependent manner, determined by Western blotting, RT-PCR, and ELISA, which was attenuated by the inhibitors of MEK1/2 (U0126), p38 MAPK (SB202190), and JNK (SP600125), or transfection with dominant negative mutants of MEK1/2, p38, and JNK, respectively. Furthermore, IL-1beta-induced cPLA2 expression and PGE2 synthesis was inhibited by a selective NF-kappaB inhibitor (helenalin) or transfection with dominant negative mutants of NF-kappaB inducing kinase (NIK), IkappaB kinase (IKK)-alpha, and IKK-beta. Consistently, IL-1beta stimulated both IkappaB-alpha degradation and NF-kappaB translocation into nucleus in these cells. NF-kappaB translocation was blocked by helenalin, but not by U0126, SB202190, and SP600125. MAPKs together with NF-kappaB-activated p300 recruited to cPLA2 promoter thus facilitating the binding of NF-kappaB to cPLA2 promoter region and expression of cPLA2 mRNA. IL-1beta-induced cPLA2 expression and PGE2 production was inhibited by actinomycin D and cycloheximide, indicating the involvement of transcriptional and translational events in these responses. These results suggest that in CTSMCs, IL-1beta-induced cPLA2 expression and PGE2 synthesis was independently mediated through activation of MAPKs and NF-kappaB pathways and was connected to p300 recruitment and activation.
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PMID:Involvement of MAPKs, NF-kappaB and p300 co-activator in IL-1beta-induced cytosolic phospholipase A2 expression in canine tracheal smooth muscle cells. 1870 82


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