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.     

IκB kinase regulation of the TPL-2/ERK MAPK pathway

Nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) activation play central roles in the induction of gene expression in innate immune cells following pathogen recognition. TPL-2 (tumor progression locus 2) is the MAP 3-kinase component of an ERK-1/2 (extracellular signal-regulated kinase 1/2) MAPK pathway activated by Toll-like receptor and tumor necrosis factor receptor family stimulation. In this review, we discuss results obtained from our laboratory and others that show that TPL-2 signaling function is directly controlled by the inhibitor of NF-κB (IκB) kinase (IKK) complex. Significantly, this means that IKK controls both NF-κB and ERK activation. TPL-2 is stoichiometrically complexed with the NF-κB inhibitory protein, NF-κB1 p105, and the ubiquitin-binding protein ABIN-2, both of which are required to maintain TPL-2 protein stability. Binding to p105 also prevents TPL-2 from phosphorylating MEK (MAPK/ERK kinase), its downstream target. Agonist stimulation releases TPL-2 from p105-inhibition by IKK-mediated phosphorylation of p105, which triggers degradation of p105 by the proteasome. This facilitates TPL-2 phosphorylation of MEK, in addition to liberating p105-associated Rel subunits to translocate into the nucleus. We also examine evidence that TPL-2 is critical for the induction of inflammation and may play a role in development and/or progression of certain types of cancer. Finally, we consider the potential of TPL-2 as an anti-inflammatory drug target for treatment of certain types of inflammatory disease and cancer.     

IκB激酶的研究进展

ＩκＢ激酶是核因子－κＢ／Ｒｅｌ蛋白参与一系列基因表达调控过程中最为关键的激酶，ＩκＫ包括分子量８５ｋＤ的ＩκＫα和分子量为８７ｋＤ的ＩκＫβ；其多肽分为激酶区，亮氨酸拉链样结构和螺旋环状结构。正常情况下，ＩκＫ以ＩκＫα，ＩκＫβ和ＮＩＫ三聚体复合物形式存在，ＮＩＫ激活后可活化ＩＫＫ而使ＩκＢｓ磷酸化，其中ＩκＫβ吏ＩκＢαＳｅｒ３２／３６和ＩκＢβＳｅｒ１９／２３等效磷酸化，而ＩκＢαＳｅｒ３     

AMP-activated protein kinase inhibits NF-κB signaling and inflammation: impact on healthspan and lifespan

Adenosine monophosphate-activated protein kinase (AMPK) is a crucial regulator of energy metabolic homeostasis and thus a major survival factor in a variety of metabolic stresses and also in the aging process. Metabolic syndrome is associated with a low-grade, chronic inflammation, primarily in adipose tissue. A low-level of inflammation is also present in the aging process. There are emerging results indicating that AMPK signaling can inhibit the inflammatory responses induced by the nuclear factor-κB (NF-κB) system. The NF-κB subunits are not direct phosphorylation targets of AMPK, but the inhibition of NF-κB signaling is mediated by several downstream targets of AMPK, e.g., SIRT1, PGC-1α, p53, and Forkhead box O (FoxO) factors. AMPK signaling seems to enhance energy metabolism while it can repress inflammatory responses linked to chronic stress, e.g., in nutritional overload and during the aging process. AMPK can inhibit endoplasmic reticulum and oxidative stresses which are involved in metabolic disorders and the aging process. Interestingly, many target proteins of AMPK are so-called longevity factors, e.g., SIRT1, p53, and FoxOs, which not only can increase the stress resistance and extend the lifespan of many organisms but also inhibit the inflammatory responses. The activation capacity of AMPK declines in metabolic stress and with aging which could augment the metabolic diseases and accelerate the aging process. We will review the AMPK pathways involved in the inhibition of NF-κB signaling and suppression of inflammation. We also emphasize that the capacity of AMPK to repress inflammatory responses can have a significant impact on both healthspan and lifespan.     

NF-κB/IκB:重要的转录调节因子

核转录因子ｋａｐｐａ Ｂ（ＮＦκＢ）是一组重要的转录调节因子,可在免疫刺激剂等多种因素作用下激活而调节基因的转录,参与调节许多与免疫功能和炎症有关的基因。ＩκＢ（Ｉｎｈｉｂｉｔｏｒｙ ＮＦκＢ）是其抑制分子,对其激活的调控起着关键作用。本文综述了ＮＦκＢ激活及调控的有关机理,为对其进一步研究提供理论依据。     

Rel/NF-κB/IκB/IKK信号转导途径研究进展

真核细胞核转录因子Rel/NF-кB家族广泛调控着自昆虫至人类的免疫和炎症反应中一系列基因的表达。静息状态下,NF-кB二聚体与抑制性蛋白IкB结合而存在于胞质中。当细胞受外源性刺激时,NF-кB活化进入核内发挥其功能。目前,外源性信号活化NF-кB的机制已初步阐明,Rel/NF-кB/IкB/IKK信号转导途径在蛋白质水平的相互调控,以及在肿瘤发生中的意义的研究也已获得一定进展。本文综述了近年来Rel/NF-кB/IкB/IKK信号转导途径的分子机制及其与肿瘤发病关系的研究进展。     

NF—κB／IκB：重要的转录调节因子

核转录因子ｋａｐｐａＢ（ＮＦ－κＢ）是一组重要的转录调节因子,可在免疫刺激剂等多种因素作用激活而调节基因的转录,参与调节许多与免疫功能和炎症有关的基因。ＩκＢ（ＩｎｈｉｂｉｔｏｒｙＮＦ－κＢ）是其抑制分子,对其激活的调控起着关键作用,本文综述了ＮＦ－κＢ激活及调控有关机理,为对其进一步研究提供理论依据。     

NF-κB超抑制物IκBαM重组腺病毒的构建

目的 在克隆IκBα基因并构建IκBαM的基础上,构建重组腺病毒AdIκBαM。方法 将IκBαM克隆至穿梭质粒,线性化后与骨架质粒共同转染BJ5183菌,构建重组腺病毒质粒。酶切及PCR法鉴定;将其线性化后转染293细胞,观察绿色荧光以确定转染结果,以Western blot法检测目的基因表达。结果 凝胶电泳及行酶切鉴定表明同源重组成功;一PCR产物测序证明确为lxBaM;以重组腺病毒质粒转染293细胞,见绿色荧光;感染293细胞得到大量病毒。结论 成功构建了IκBαM重组腺病毒,为进一步研究奠定了基础。     

Nuclear export of the NF-κB inhibitor IκBα is required for proper B cell and secondary lymphoid tissue formation

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Highlights? IκBα NES is essential for efficient nuclear export of cRel in vivo ? IκBα NES is required for constitutive and canonical cRel dimer activation in B cells ? IκBα NES also indirectly controls noncanonical NF-κB activation in B cells ? IκBα NES deficiency causes multiple severe defects in vivo