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)

The inhibitor of NF-kappaB (I-kappaB) kinase (IKK) complex consists of 3 subunits, IKK1, IKK2, and NF-kappaB essential modulator (NEMO), and is involved in the activation of NF-kappaB by various stimuli. IKK2 or NEMO constitutive knockout mice die during embryogenesis as a result of massive hepatic apoptosis. Therefore, we examined the role of IKK2 in TNF-induced apoptosis and ischemia/reperfusion (I/R) injury in the liver by using conditional knockout mice. Hepatocyte-specific ablation of IKK2 did not lead to impaired activation of NF-kappaB or increased apoptosis after TNF-alpha stimulation whereas conditional NEMO knockout resulted in complete block of NF-kappaB activation and massive hepatocyte apoptosis. In a model of partial hepatic I/R injury, mice lacking IKK2 in hepatocytes displayed significantly reduced liver necrosis and inflammation than wild-type mice. AS602868, a novel chemical inhibitor of IKK2, protected mice from liver injury due to I/R without sensitizing them toward TNF-induced apoptosis and could therefore emerge as a new pharmacological therapy for liver resection, hemorrhagic shock, or transplantation surgery.
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PMID:Deletion of IKK2 in hepatocytes does not sensitize these cells to TNF-induced apoptosis but protects from ischemia/reperfusion injury. 1596 93

Toll-like receptor-4 (TLR4) and its signaling molecule interleukin-1 receptor-associated kinase (IRAK-1) play an important role in host defense and tissue inflammation. Intriguingly, systemic administration of lipopolysaccharide (LPS), the agonist for TLR4, confers a cardio-protective effect against ischemic injury. However, the mechanisms leading to the cardiac protection remain largely unknown. The present study was designed to investigate the role of TLR4 activation by LPS in protecting cardiomyocytes (CM) against apoptosis in an in vitro model of ischemia and to explore the downstream mechanisms leading to the protective effect. Incubation with LPS led to activation of IRAK-1 and protected CMs against serum deprivation (SD)-induced apoptosis as demonstrated by DNA laddering, histone-DNA fragment enzyme-linked immunosorbent assay, and activation of caspase-3. Phosphatidylinositol 3-kinase/Akt, extracellular signal-regulated kinase 1/2, and IkappaB kinase beta appear to contribute to the anti-apoptotic effect of LPS since the specific inhibitors, wortmannin, PD98059, and dominant negative IKKbeta transgene expression reversed the LPS effect. To assess whether LPS improves CM function, we examined intracellular Ca(2+) transients and cell shortening in single adult rat CMs. SD for 6 h dramatically inhibited Ca(2+) transients and CM contractility. LPS at 500 ng/ml significantly improved the [Ca(2+)](i) transients and enhanced contractility in control CMs as well as in CMs subjected to SD. Importantly, transient ischemia led to rapid activation of IRAK-1 in cultured CMs and in adult rat myocardium. Adenovirus-mediated transgene expression of IRAK-1 but not its kinase-deficient mutant IRAK-1(K239S) protected CMs against SD-induced apoptosis. Taken together, these data suggest an important role of TLR4 signaling via IRAK-1 in protecting against SD-induced apoptosis.
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PMID:Lipopolysaccharide improves cardiomyocyte survival and function after serum deprivation. 1579 10

The inhibitor of NF-kappaB (I-kappaB) kinase (IKK) complex consists of 3 subunits, IKK1, IKK2, and NF-kappaB essential modulator (NEMO), and is involved in the activation of NF-kappaB by various stimuli. IKK2 or NEMO constitutive knockout mice die during embryogenesis as a result of massive hepatic apoptosis. Therefore, we examined the role of IKK2 in TNF-induced apoptosis and ischemia/reperfusion (I/R) injury in the liver by using conditional knockout mice. Hepatocyte-specific ablation of IKK2 did not lead to impaired activation of NF-kappaB or increased apoptosis after TNF-alpha stimulation whereas conditional NEMO knockout resulted in complete block of NF-kappaB activation and massive hepatocyte apoptosis. In a model of partial hepatic I/R injury, mice lacking IKK2 in hepatocytes displayed significantly reduced liver necrosis and inflammation than wild-type mice. AS602868, a novel chemical inhibitor of IKK2, protected mice from liver injury due to I/R without sensitizing them toward TNF-induced apoptosis and could therefore emerge as a new pharmacological therapy for liver resection, hemorrhagic shock, or transplantation surgery.
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PMID:Activation and function of hepatocyte NF-kappaB in postischemic liver injury. 1577 10

The IkappaB kinase complex IKK is a central component of the signaling cascade that controls NF-kappaB-dependent gene transcription. So far, its function in the brain is largely unknown. Here, we show that IKK is activated in a mouse model of stroke. To investigate the function of IKK in brain ischemia we generated mice that contain a targeted deletion of Ikbkb (which encodes IKK2) in mouse neurons and mice that express a dominant inhibitor of IKK in neurons. In both lines, inhibition of IKK activity markedly reduced infarct size. In contrast, constitutive activation of IKK2 enlarged the infarct size. A selective small-molecule inhibitor of IKK mimicked the effect of genetic IKK inhibition in neurons, reducing the infarct volume and cell death in a therapeutic time window of 4.5 h. These data indicate a key function of IKK in ischemic brain damage and suggest a potential role for IKK inhibitors in stroke therapy.
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PMID:IKK mediates ischemia-induced neuronal death. 1628 24

Activated nuclear factor-kappaB (NFkappaB) has been shown to increase transcription of several genes that could potentially contribute to neuronal damage, such as proinflammatory cytokines, chemokines, and inducible nitric oxide synthase. The aim of our study was to investigate whether inhibition of NFkappaB activation could prevent hypoxia/ischemia (HI)-induced cerebral damage in neonatal rats. We used a cell permeable peptide (NEMO binding domain [NBD] peptide) that is known to prevent the association of the regulatory protein NEMO with IKK, the kinase that activates NFkappaB. Via this mechanism, the NBD peptide can specifically block the activation of NFkappaB, without inhibiting basal NFkappaB activity. Cerebral HI was induced in neonatal rats by occlusion of the right carotid artery followed by 90 min of hypoxia (Fio(2) = 0.08). Immediately upon reoxygenation, as well as 6 and 12 h later, rats were treated with vehicle or NBD peptide (20 mg/kg i.p.). Histologic analysis of brain damage was performed at 6 wk after HI. To assess NFkappaB activation, electromobility shift assays (EMSAs) were performed on brain nuclear extracts obtained 6 h after reoxygenation. Increased NFkappaB activity could be shown at 6 h after HI in both hemispheres. Peripheral administration of NBD peptide prevented this HI-induced increase in NFkappaB activity in both hemispheres. Histologic analysis of long-term cerebral damage revealed that inhibition of NFkappaB activation by administration of NBD peptide at 0, 6, and 12 h after HI resulted in an increment of neuronal damage. In conclusion, our data suggest that inhibition of NFkappaB activation using NBD peptide early after HI increases brain damage in neonatal rats.
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PMID:Selective inhibition of nuclear factor-kappaB activation after hypoxia/ischemia in neonatal rats is not neuroprotective. 1643 84

Nitric oxide (NO), applied by inhalation or released from NO donors, has been used to reduce the expression of cell adhesion molecules (CAM) and ameliorate other consequences of ischemia/reperfusion (I/R) injury. In this study, we have assessed the time frames of pretreatment and of the duration of the preconditioned state using human umbilical vein endothelial cells (HUVECs) and the NO donor, SNAP, in combination with cysteine. The induction of vascular cell adhesion molecule (VCAM), intercellular adhesion molecule (ICAM) and E-selectin by the cytokines TNFalpha and IL-1beta, and by bacterial lipopolysaccharide (LPS) was reduced by SNAP/Cys preincubation (30 min, 1mM) to less than 10% of controls. This refractory state in respect to cytokine-induced CAM expression persisted for 6h after washout of the NO donor in the combination TNFalpha/VCAM, and a partial block was still observed after 8h. The effect was not mediated by the cGMP pathway, as was demonstrated by using the inhibitor of guanylyl cyclase, ODQ, and the cGMP analogue, 8-Br-cGMP. The TNFalpha-induced expression of CAM was exclusively dependent on the transcription factor NFkappaB since the inhibitor of NFkappaB activation, BAY 11-7082, completely blocked the induction. The TNFalpha-induced phosphorylation and degradation of the inhibitor of kappaB (IkappaBalpha) was suppressed for up to 8h after SNAP/Cys pretreatment. The inhibitory S-nitrosation of IkappaB kinase (IKKbeta), as assessed by the biotin-switch-procedure and immunoprecipitation, was only detectable immediately after SNAP/Cys incubation but not at later time points. In summary, a short preincubation of HUVEC with SNAP/Cys results in a persistent suppression of NFkappaB-dependent expression of CAM. The stabilization of IkappaBalpha over the same time span may be causally related to this effect.
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PMID:Nitric oxide donor-induced persistent inhibition of cell adhesion protein expression and NFkappaB activation in endothelial cells. 1650 56

TNF-alpha activates several intracellular pathways to regulate inflammation, cell death, and proliferation. In the liver, TNF-alpha is not only a mediator of hepatotoxicity but also contributes to the restoration of functional liver mass by driving hepatocyte proliferation and liver regeneration. This review summarizes recent advances in TNF-alpha signaling mechanisms that demonstrate how the IKK, ROS, and JNK pathways interact with each other to regulate hepatocyte apoptosis and proliferation. Activation of these pathways is causatively linked to liver injury induced by concanavalin A, TNF-alpha, and ischemia-reperfusion and to liver regeneration and hepatocarcinogenesis. In light of recent findings, pharmacological inhibitors of JNK and IKK and antioxidants may be promising new tools for the treatment of hepatitis, ischemia-reperfusion injury, and hepatocellular carcinoma.
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PMID:Mechanisms of Liver Injury. I. TNF-alpha-induced liver injury: role of IKK, JNK, and ROS pathways. 1653 70

Mild hypothermia is one of the most robust neuroprotectant studied in the laboratory to date. The reasons for this protective effect are likely multifactorial, but work from our laboratory and others have shown that this protection is associated with remarkable suppression of the inflammatory response that accompanies brain ischemia. Consistently, laboratories have shown that small decreases in brain temperature to 30-34 degrees C result in reduced inflammatory cell infiltrate, less microglial activation, and reduction of a variety of inflammatory mediators such as nitric oxide, inflammatory cytokines and superoxide. Nuclear factor-kappaB (NFkappaB) is a transcription factor that is activated after cerebral ischemia. NFkappaB activation leads to the expression of many inflammatory genes involved in the pathogenesis of stroke. Our laboratory has shown that hypothermia decreases NFkappaB translocation and binding activity, by affecting NFkappaB regulatory proteins. Mild hypothermia appears to suppress phosphorylation of NFkappaB's inhibitory protein (IkappaB-alpha) by decreasing expression and activity of IkappaB kinase-gamma (IKK). As a consequence, hypothermia suppressed gene expression of two NFkappaB target genes, inducible nitric oxide synthase and TNF-alpha. These data suggest that the protective effect of hypothermia on cerebral injury is, in part, related to NFkappaB inhibition due to decreased activity of IKK.
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PMID:Influence of hypothermia on post-ischemic inflammation: role of nuclear factor kappa B (NFkappaB). 1675 Aug 72

During hepatic ischemia/reperfusion (I/R), proinflammatory cytokines such as tumor necrosis factor alpha and interleukin (IL) 1beta stimulate the induction of inducible nitric oxide synthase (iNOS) in hepatocytes, followed by massive production of nitric oxide. We hypothesized that I/R upregulated the susceptibility of hepatocytes to confer the induction of iNOS gene expression. This study was designed to investigate whether cell susceptibility occurs in response to I/R and to delineate the mechanisms underlying the susceptibility. Hepatocytes were isolated from rats with hepatic I/R or sham, cultured, and treated with IL-1beta. The iNOS induction and its signal including inhibitor kappaB (IkappaB) kinase/nuclear factor kappaB (NF-kappaB) and Akt/type 1 interleukin 1 receptor (IL-1R1) were analyzed. Hepatocytes isolated from rats with I/R markedly increased the production of nitric oxide when stimulated by IL-1beta as compared with sham control. Ischemia/R also increased the levels of iNOS protein and its messenger RNA. Furthermore, I/R enhanced the activation of transcription factor NF-kappaB and the transactivation of iNOS promoter. However, I/R had no effects on the degradation of IkappaB and the nuclear translocation of p65 subunit of NF-kappaB. In contrast, I/R increased the phosphorylation of Akt and the upregulation of IL-1R1 induction, which is essential signal for the transcriptional activation of iNOS in addition to IkappaB kinase/NF-kappaB. These results demonstrate that I/R may augment hepatocyte susceptibility for the induction of iNOS gene expression through the enhancement of IL-1R1.
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PMID:Hepatic ischemia/reperfusion upregulates the susceptibility of hepatocytes to confer the induction of inducible nitric oxide synthase gene expression. 1687 24

Although heat preconditioning has been known to be protective in various types of injury, the precise molecular mechanism for this is unclear. Recent observations that indicate that previous heat shock has an anti-inflammatory, antiapoptotic effect led to this investigation of the in vivo effect of heat preconditioning on NF-kappaB activation and inflammation and also on tubular cell injury in ischemic acute renal failure (ARF). Heat preconditioning provided marked functional protection and also reduced histologic evidence of tubular necrosis. Ischemia/reperfusion-induced NF-kappaB activation was suppressed by heat preconditioning with a subsequent decrease in monocyte chemoattractant protein-1 expression and inflammatory cell infiltration. Heat preconditioning also suppressed the accumulation of phosphorylated inhibitory kappaBalpha (IkappaBalpha) with a resultant depletion of cytoplasmic IkappaBalpha, indicating that heat preconditioning blocked the activation of the IkappaB kinase complex. Tubular cell apoptosis, determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, also was decreased by heat preconditioning, and this was accompanied by decreased caspase 3 activation. Among several heat-shock proteins (HSP), HSP-70 was induced primarily by heat preconditioning. Inhibition of HSP-70 by quercetin almost completely reversed the functional protection that was provided by heat preconditioning. These data provide evidence that HSP-70 affords protection via inhibition of NF-kappaB-mediated inflammation and also inhibition of the cell death pathway in ischemic ARF. Further elucidation of the cytoprotective mechanism of stress proteins could facilitate new target or drug development in the treatment of ARF.
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PMID:Heat preconditioning attenuates renal injury in ischemic ARF in rats: role of heat-shock protein 70 on NF-kappaB-mediated inflammation and on tubular cell injury. 1702 Dec 70


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