A novel association between filamin A and NF-κB inducing kinase couples CD28 to inhibitor of NF-κB kinase α and NF-κB activation

CD28 costimulatory molecule plays a critical role in the activation of NF-κB. Indeed, while stimulation of T cells with either professional APCs or anti-TCR plus anti-CD28 antibodies efficiently activates NF-κB, TCR alone fails to do that. Moreover, CD28 stimulation by B7 in the absence of TCR may activate IκB kinase α (IKKα) and a non-canonical NF-κB2-like pathway, in human primary CD4(+) T cells. Despite its functional relevance in NF-κB activation, the molecules connecting autonomous CD28-mediated signals to IKKα and NF-κB activation remain still unknown. In searching for specific upstream activators linking CD28 to the IKKα/NF-κB cascade, we identify a novel constitutive association between filamin A (FLNa) and the NF-κB inducing kinase (NIK), in both Jurkat and human primary T cells. Following CD28 engagement by B7, in the absence of TCR, FLNa-associated NIK is activated and induces IKKα kinase activity. Both proline (P(208)YAP(211)P(212)) and tyrosine residues (Y(206)QPY(209)APP) within the C-terminal proline-rich motif of CD28 are involved in the recruitment of FLNa/NIK complexes to the membrane as well as in the activation of NIK and IKKα.     

The noncanonical NF-κB pathway

The noncanonical nuclear factor-κB (NF-κB) signaling pathway mediates activation of the p52/RelB NF-κB complex and, thereby, regulates specific immunological processes. This NF-κB pathway relies on the inducible processing of NF-κB2 precursor protein, p100, as opposed to the degradation of IκBα in the canonical NF-κB pathway. A central signaling component of the noncanonical NF-κB pathway is NF-κB-inducing kinase (NIK), which functions together with a downstream kinase, IKKα (inhibitor of NF-κB kinase α), to induce phosphorylation-dependent ubiquitination and processing of p100. Under normal conditions, NIK is targeted for continuous degradation by a tumor necrosis factor (TNF) receptor-associated factor-3 (TRAF3)-dependent E3 ubiquitin ligase. In response to signals mediated by a subset of TNF receptor superfamily members, NIK becomes stabilized as a result of TRAF3 degradation, leading to the activation of noncanonical NF-κB. This review discusses both the historical perspectives and the recent progress in the regulation and biological function of the noncanonical NF-κB pathway.     

右美托咪定对创伤后应激障碍大鼠核因子κB抑制蛋白激酶/核因子κB抑制蛋白α/核因子κB通路及认知功能障碍的影响

目的 探讨右美托咪定（DEX）对创伤后应激障碍大鼠（PTSD）核因子κB抑制蛋白激酶（IKK）/核因子κB抑制蛋白α（IκBα）/核因子κB（NF-κB）通路及认知功能障碍的影响。 方法 将大鼠按照随机数字表法分为空白对照（control）组、模型（model）组、阳性对照（positive）组和DEX组。除control组外,其余各组使用单一延长应激法（SPS）构建PTSD模型,并于模型制作后分别给予相应药物。旷场实验和Morris水迷宫法检测大鼠自主活动和学习记忆能力;HE染色法观察大脑皮层和海马组织病理变化;ELISA和Western blotting检测海马组织白细胞介素（IL）-1β、IL-6和肿瘤坏死因子α（TNF-α）含量及IKK、IκBα、嘌呤能离子通道型受体7（P2X7R）和富含亮氨酸重复结构域蛋白3（NALP3）表达水平;凝胶电泳迁移率转变分析（EMSA）评价NF-κB活性。 结果 与control组相比,model组大鼠大脑皮层及海马CA1区出现结构紊乱,细胞核固缩等病理变化,大鼠自主活动和学习记忆能力降低（P<0.05）, IL-1β、IL-6和TNF-α含量、IKK、IκBα、P2X7R和NALP3表达水平及NF-κB活性升高（P<0.05）;与model组相比,positive组和DEX组大鼠大脑皮层及海马CA1区病理现象缓解,上述指标变化均与model组相反（P<0.05）。 结论 DEX可显著提高PTSD大鼠自主活动和学习记忆能力,减少海马组织炎症反应,改善认知功能障碍,可能与下调IKK/IκBα/NF-κB通路有关。     

5,7-Dihydroxy-3,4,6-trimethoxyflavone inhibits intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 via the Akt and nuclear factor-κB-dependent pathway, leading to suppression of adhesion of monocytes and eosinophils to bronchial epithelial cells

5,7-Dihydroxy-3',4',6'-trimethoxyflavone (eupatilin), the active pharmacological ingredient from Artemisia asiatica Nakai (Asteraceae), is reported to have a variety of anti-inflammatory properties in intestinal epithelial cells. However, little information is known about the molecular mechanism of eupatilin-induced attenuation of bronchial epithelial inflammation. This study investigates the role of eupatilin in the adhesion of inflammatory cells such as monocytes and eosinophils to bronchial epithelial cells. Stimulation of a human bronchial epithelial cell line (BEAS-2B) with tumour necrosis factor-α (TNF-α) increased the expression of surface adhesion molecules, including intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), in which eupatilin significantly inhibited the expression of those adhesion molecules in a dose-dependent manner. Eupatilin suppressed the TNF-α-induced activation of IκBα and nuclear factor-κB (NF-κB) signals in BEAS-2B cells. The IκB kinase (IKK) activation was also significantly reduced in eupatilin-pre-treated BEAS-2B and primary normal human bronchial epithelial (NHBE) cells. However, eupatilin did not influence AP-1 activity in TNF-α-stimulated cells. Suppression of NF-κB signalling induced by eupatilin resulted in the inhibition of the expression of adhesion molecules and the adhesion of monocytes and eosinophils to BEAS-2B cells. Furthermore, eupatilin suppressed the phosphorylation of Akt in TNF-α-stimulated BEAS-2B and NHBE cells, leading to down-regulation of NF-κB activation and adhesion molecule expression and finally to suppression of the inflammatory cell adhesion to epithelial cells. These results suggest that eupatilin can inhibit the adhesion of inflammatory cells to bronchial epithelial cells via a signalling pathway, including activation of Akt and NF-κB, as well as expression of adhesion molecules.     

Roburic Acid Suppresses NO and IL-6 Production <Emphasis Type="Italic">via</Emphasis> Targeting NF-κB and MAPK Pathway in RAW264.7 Cells

In the present study, we investigated the anti-inflammatory effect of roburic acid on production of nitric oxide (NO) and interlukin-6 (IL-6) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. We found that roburic acid reduced production of NO and IL-6, and the expression of inducible nitric oxide synthases (iNOS). Meanwhile, phosphorylation of inhibitor of κBα (IκBα) and IκB kinase α/β (IKKα/β), as well as translocation of nuclear factor-κB (NF-κB) to the nucleus, was suppressed by roburic acid treatment. In addition, phosphorylation of mitogen-activated protein kinase (MAPKs) including p38 and c-Jun-NH₂-terminal kinase (JNK) was inhibited. Roburic acid exhibited inhibitory activities on production of NO and IL-6 via blocking IKK/IκB/NF-κB and MAPKs pathway, suggesting the potential application as a drug candidate for therapy of inflammatory diseases.     

Recombinant TB10.4 of Mycobacterium bovis induces cytokine production in RAW264.7 macrophages through activation of the MAPK and NF-κB pathways via TLR2

The TB10.4 antigen of Mycobacterium bovis/Mycobacterium tuberculosis induces a strong Th1 CD4+ T-cell response. Thus, it is currently under intensive study as a possible vaccine candidate. However, how TB10.4 activates innate immune cells is unclear. How TB10.4 interacts with toll-like receptors (TLRs) and signaling pathways responsible for active inflammation have also not been fully elucidated. Here, as stimulated RAW264.7 cells with recombinant TB10.4 (rTB10.4), derived from M. bovis, increased TNF-α, IL-6 and IL-12 p40 secretin in a dose-dependent manner. Blocking assays showed that TLR2-, but not TLR4-neutralizing antibody reduced expression of TNF-α, IL-6 and IL-12 p40 in RAW264.7 cells. rTB10.4 stimulation activated p38 kinase (p38) and extracellular-regulated kinase (ERK) was TLR2-dependent, whereas inhibition of p38 and ERK activity significantly reduced TNF-α, IL-6 and IL-12 p40 production. Furthermore, rTB10.4 stimulation of RAW264.7 cells resulted in TLR2-mediated activation of NF-κB and induced translocation of NF-κB p65 from the cytoplasm to the nucleus via IκBα degradation. rTB10.4-induced TNF-α, IL-6 and IL-12 p40 release was attenuated by the specific IκB phosphorylation inhibitor, BAY 11-7082. These findings indicate that the M. bovis-derived rTB10.4 induced production of TNF-α, IL-6 and IL-12 p40 involves p38, ERK and NF-κB via the TLR2 pathway.     

酮咯酸氨丁三醇抑制膝骨关节炎模型大鼠炎性反应

目的探究酮咯酸氨丁三醇(KT)对膝骨关节炎(KOA)模型大鼠炎性疼痛的影响,并从Toll样受体4(TLR4)/核因子-κB(NF-κB)炎性通路初步探究其作用机制。方法取大鼠,用随机数字表法分为:对照组、模型组、KT低(1 mg/kg)、高(4 mg/kg)剂量组、TAK-242组(TLR4拮抗剂,1 mg/kg);除对照组外,其余各组均用改良Hulth法复制大鼠右膝KOA模型;肌肉注射KT 1次/d,经尾静脉注射TAK-2422次/周。观察大鼠膝关节肿胀程度、活动状况,对自发疼痛行为步态评分及检测热痛阈值;取滑膜组织,HE及Masson染色检测组织病理形态变化及纤维组织增生状况;ELISA检测滑膜组织炎性因子白细胞介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)水平;Western blot检测神经突蛋白(neuritin)及通路蛋白TLR4、NF-κB及p-NF-κB、骨桥蛋白(OPN)、整合素金属蛋白酶4(ADAM4)蛋白表达。结果与对照组相比,模型组大鼠关节肿胀、疼痛、滑膜炎性损伤及纤维组织增生等KOA病理症状严重,滑膜IL-1β、TNF-α水平及疼痛指标neuritin表达升高、TLR4/NF-κB p65通路及相关蛋白OPN、ADAM4表达升高(P<0.05)。与模型组相比,KT低、高剂量组及TAK-242组大鼠KOA疼痛、滑膜炎性反应等病理症状缓解,TLR4/NF-κB p65通路及相关蛋白表达降低(P<0.05)。结论KT可缓解KOA模型大鼠滑膜炎性反应及疼痛症状,其缓解作用可能与阻断TLR4/NF-κB通路激活有关。     

沙立度胺对大鼠肝纤维化核因子-κB和肿瘤坏死因子-α表达的影响

目的： 观察沙立度胺抗大鼠肝纤维化的疗效和对NF-κB和TNF-α表达的影响。方法： 四氯化碳腹腔注射诱导大鼠肝纤维化模型，治疗组于造模同时用沙立度胺10 mg·kg^-1·d^-1和100 mg·kg^-1·d^-1灌胃8周。观察肝组织病理学改变，检测肝功能、血清肝纤维化指标及肝组织羟脯氨酸含量，免疫组化检测NF-κB p65、α-SMA 在肝内的表达和分布，Western blotting检测肝组织NF-κB p65、IκBα、TNF-α蛋白的表达，RT-PCR检测肝组织TNF-α mRNA表达。结果： 高剂量沙立度胺治疗组肝脏炎症及纤维化程度低于模型组；其ALT、AST水平,HA、LN及羟脯氨酸含量，肝组织细胞核NF-κB p65和肝组织α-SMA蛋白表达，以及肝组织TNF-α mRNA和蛋白表达均低于模型组(P<0.01）；而PA水平和细胞质中IκBα蛋白表达高于模型组(P<0.01)。结论： 沙立度胺可有效地抑制实验性大鼠肝纤维化的发展，通过抑制IκB解离和降解从而减弱NF-κB通路对TNF-α表达的诱导可能是它发挥疗效的机制之一。     

IKK biology

The inhibitor of nuclear factor-κB (IκB) kinase (IKK) complex is the master regulator of the NF-κB signaling pathway. The activation of the IKK complex is a tightly regulated, highly stimulus-specific, and target-specific event that is essential for the plethora of functions attributed to NF-κB. More recently, NF-κB-independent roles of IKK members have brought increased complexity to its biological function. This review highlights some of the major advances in the studies of the process of IKK activation and the biological roles of IKK family members, with a focus on NF-κB-independent functions. Understanding these complex processes is essential for targeting IKK for therapeutics.     

黄芪总皂苷对脂多糖诱导的BV2小胶质细胞的抗炎机制

目的:探讨黄芪总皂苷(TAS)对脂多糖(LPS)诱导的BV2小胶质细胞炎症损伤的抗炎作用机制.方法:用CCK-8法筛选出对细胞活力无抑制的药物浓度;用浓度为1 mg/L的LPS刺激BV2细胞24 h,建立细胞炎症模型;实验分为正常组、LPS组、高剂量(75 mg/L)TAS组和低剂量(50 mg/L)TAS组;应用流式...     

NF-κB regulation: lessons from structures

The signaling module that specifies nuclear factor-κΒ (NF-κB) activation is a three-component system: NF-κB, inhibitor of NF-κΒ (IκΒ), and IκΒ kinase complex (IKK). IKK receives upstream signals from the surface or inside the cell and converts itself into a catalytically active form, leading to the destruction of IκB in the inhibited IκB:NF-κB complex, leaving active NF-κB free to regulate target genes. Hidden within this simple module are family members that all can undergo various modifications resulting in expansion of functional spectrum. Three-dimensional structures representing all three components are now available. These structures have allowed us to interpret cellular observations in molecular terms and at the same time helped us to bring forward new concepts focused towards understanding the specificity in the NF-κB activation pathway.     

A mechanism for the action of the compound DA-6034 on NF-κB pathway activation in Helicobacter pylori-infected gastric epithelial cells

DA-6034 is a synthetic derivative of eupatilin, a flavonoid with anti-inflammatory effects. The aim of this study was to investigate the effects of DA-6034 on the interactions between IκB kinase (IKK) and heat shock protein 90 (Hsp90), and activation of the nuclear factor-kappaB (NF-κB) signalling pathway in human gastric epithelial cells infected with Helicobacter pylori. MKN-45 gastric epithelial cell line was treated with DA-6034 and H. pylori. DA-6034 significantly inhibited NF-κB activation and upregulated the expressions of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 in MKN-45 cells infected with H. pylori. However, DA-6034 did not influence activator protein-1 DNA binding activity in H. pylori-infected gastric epithelial cells. Pretreatment with DA-6034 attenuated the H. pylori-induced increase in IKK activity, and Hsp90 was associated with IKK-α and IKK-γ in MKN-45 cells. Treatment with DA-6034 dissociated the Hsp90 and IKK-γ complex in H. pylori-infected cells, leading to the inhibition of IL-8 expression. These results suggest that the eupatilin derivative 7-carboxymethyloxy-3',4',5-trimethoxy flavone has anti-inflammatory activity in gastric epithelial cells infected with H. pylori through the promotion of the dissociation of the IKK-γ-Hsp90 complex and suppression of NF-κB signalling.     

Thymol Inhibits LPS-Stimulated Inflammatory Response via Down-Regulation of NF-κB and MAPK Signaling Pathways in Mouse Mammary Epithelial Cells

Thymol is a natural monoterpene phenol primarily found in thyme, oregano, and tangerine peel. It has been shown to possess anti-inflammatory property both in vivo and in vitro. In the present paper, we studied the anti-inflammatory effect of thymol in lipopolysaccharide (LPS)-stimulated mouse mammary epithelial cells (mMECs). The mMECs were stimulated with LPS in the presence or absence of thymol (10, 20, 40 μg/mL). The concentrations of tumor necrosis factor α (TNF-α), interleukin (IL)-6, and IL-1β in the supernatants of culture were determined using enzyme-linked immunosorbent assay. Cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), nuclear factor-κB (NF-κB), and inhibitor protein of NF-κB (IκBα) were measured using western blot. The results showed that thymol markedly inhibited the production of TNF-α and IL-6 in LPS-stimulated mMECs. The expression of iNOS and COX-2 was also suppressed by thymol in a dose-dependent manner. Furthermore, thymol blocked the phosphorylation of IκBα, NF-κB p65, ERK, JNK, and p38 mitogen-activated protein kinases (MAPKs) in LPS-stimulated mMECs. These results indicate that thymol exerted anti-inflammatory property in LPS-stimulated mMECs by interfering the activation of NF-κB and MAPK signaling pathways. Thereby, thymol may be a potential therapeutic agent against mastitis.