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Event: 2034

Key Event Title

A descriptive phrase which defines a discrete biological change that can be measured. More help

Induction, Nuclear Transcription Factor kappa B (NFkB)

Short name
The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. More help
Induction, NFkB
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Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. More help
Level of Biological Organization

Cell term

The location/biological environment in which the event takes place.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable.  Further information on Event Components and Biological Context may be viewed on the attached pdf. More help
Cell term

Organ term

The location/biological environment in which the event takes place.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable.  Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Key Event Components

The KE, as defined by a set structured ontology terms consisting of a biological process, object, and action with each term originating from one of 14 biological ontologies (Ives, et al., 2017; Biological process describes dynamics of the underlying biological system (e.g., receptor signalling).Biological process describes dynamics of the underlying biological system (e.g., receptor signaling).  The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signaling by that receptor).  Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description.  To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons.  If a desired term does not exist, a new term request may be made via Term Requests.  Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add.  Further information on Event Components and Biological Context may be viewed on the attached pdf. More help
Process Object Action
activation of NF-kappaB-inducing kinase activity NF-kappaB complex increased

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE. Clicking on the name of the AOP will bring you to the individual page for that AOP. More help
AOP Name Role of event in AOP Point of Contact Author Status OECD Status
TLR4 activation in microglia leads to neurodegeneration KeyEvent Arthur Author (send email) Under development: Not open for comment. Do not cite

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KE.In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help
Term Scientific Term Evidence Link
human Homo sapiens High NCBI
mouse Mus musculus High NCBI
rat Rattus norvegicus Moderate NCBI
Pan troglodytes Pan troglodytes High NCBI
Macaca mulatta Macaca mulatta Moderate NCBI
Canis lupus familiaris Canis lupus familiaris High NCBI

Life Stages

An indication of the the relevant life stage(s) for this KE. More help
Life stage Evidence
Not Otherwise Specified High

Sex Applicability

An indication of the the relevant sex for this KE. More help
Term Evidence
Male High

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. More help

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a generic term comprising a family of proteins that play a critical role in both innate and adaptive immunity, cell proliferation, apoptosis and inflammation.  Induction of NF-κB can triggered by a variety of factors, including interleukins, tumor necrosis factors, viral proteins, ultraviolet radiation, reactive oxygen species, nitric oxide and pro-inflammatory cytokines (Li and Verma, 2002), but the most studied mechanism is induction by toll-like receptor signaling – in particular TLR2 and TLR4 (Arancibia et al., 2007).

The mammalian NF-κB family of proteins consists of NF-κB1 (p50), NF-κB2 (p52), RelA (p65), RelB and c-Rel, which are present as dimers in the cell cytosol, attached to inhibitors of κB (IκB) until activated (Gilmore, 2006). Induction of NF-κB occurs when an upstream signal activates IKB kinase (IKK) leading to phosphorylation and degradation of IκB. Degradation of IκB releases NF-κB subunit dimers and allows for subsequent phosphorylation and translocation to the cell nucleus. Inside the nucleus,  NF-κB dimers bind to DNA motifs and are critical transcriptional regulators in the innate immune response, mediating rapid upregulation of gene transcription (Li and Verma, 2002).

When NF-κB dimers containing p65 form complexes with CREB-binding protein (CBP) they can bind to DNA, inducing the transcription and rapid upregulation of a variety of proteins depending on the cell and tissue type. Additionally, NF-κB can work in concert with activator protein-1 (AP-1) to further stimulate gene transcription (Ye et al., 2014), and plays a regulatory role in T cell function (Gerondakis et al., 2014). In immune cells in the periphery, and glia within the CNS, p65/CBP binding to DNA is associated with a potent inflammatory response and results in upregulation of  pro-inflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and Interleukin 1beta (IL-1β) (Zhong et al., 2002; Giridharan and Srinivasan, 2018), and plays a complex role in the priming, but not necessarily the activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome (Kelley et al., 2019). Nuclear NF-κB also upregulates IκB repressor transcription in a negative-feedback loop which mediates deactivation and transportation of NF-κB dimers back to the cytosol (Giridharan and Srinivasan, 2018).

How It Is Measured or Detected

A description of the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements.These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA). Do not provide detailed protocols. More help

Induction of NF-κB is rapid and transient and is primarily detected using in vitro assays. Phosphorylated NF-κB (which is a necessary step in activation) can be detected by the application of phospho-specific antibodies to members of the NF-κB family of proteins such as p65 and p50, which form homo and heterodimers that enable translocation to the nucleus.  These proteins can then be detected using flow cytometry (Maguire et al., 2015).  Alternatively, phosphorylation can be measured using commercially available antibodies in western blots or immunohistochemistry/microscopy.  Numerous other methods exist for detecting NF-κB complexes bound to DNA, including quantitative enzyme-linked immunosorbent assay (ELISA), chromatin immunoprecipitation combined with PCR (CHIP-seq), and live-cell imaging using GFP-tagged reporter cell-lines (for a full review of available techniques see (Ernst et al., 2018)).

Domain of Applicability

A description of the scientific basis for the indicated domains of applicability and the WoE calls (if provided).  More help

NF-κB was first discovered 35 years ago in B cells (Sen and Baltimore, 1986) and was subsequently discovered to be family of related proteins. NF-κB protein subunit expression (homologs and orthologs) is conserved across most animal species including mammals, invertebrates, cnidarians and insects, (with the exception of yeasts and c. elegans), although some species-specific polymorphisms exist (Graef et al., 2001; Sullivan et al., 2009). By far, mammalian NF-κB is the most studied: Subunits p50, p52, and p65 are present in most cell types, whereas RelB and c-Rel are only found in a subset of immune cells (Gilmore and Gerondakis, 2011; Oeckinghaus and Ghosh, 2009).

The induction of NF-κB has been directly measured in a large variety of cell types, both in vivo and vitro, primarily using human and mouse tissue, for which there now exist commercial reporter lines for human HEK293, ME-180, HeLa, Jurkat and THP-1 cells, mouse RAW 264.7 cells, Chinese hamster ovary (CHO-K1) cells. More recently reporter mouse lines have been developed, with 3 different models available from JAX.ORG and a newly developed ROSA26 knock-in NF-κB reporter (KappaBle) line that allows visualization of NF-κB activity in any cells which stably express and activate NF-κB  (Tortola et al., 2022).

The study of NF-κB is broadly expressed in cells of both sexes, however sex differences have been found in basal NF-κB activation in mice (Villa et al., 2018) and down-stream gene expression impacting neuroprotection in human neurons (Ruiz-Perera et al., 2018) and murine bone mass (Zarei et al., 2019).  

NF-κB is present in differentiated cells at all life stages and is crucial during development, with loss of function leading to severe developmental and often fatal defects in mice and humans (Espín-Palazón and Traver, 2016). NF-κB regulates cell differentiation in adult stem cells, but is not present in mouse and human embryonic stem cells (Kaltschmidt et al., 2021). NF-κB has been implicated in the development and treatment of cancer, aging, autoimmune and degenerative disorders in humans with many studies leveraging mouse models (Miraghazadeh and Cook, 2018; Salminen and Kaarniranta, 2009; Sun et al., 2013; Xia et al., 2014; Zhang et al., 2021). Numerous knockout mouse models have been developed to study human disease-causing polymorphisms in NF-κB genes, with the biggest species differences being not in the NF-κB family of proteins but in the inhibitors of NF-κB, the IKK proteins (Zhang et al., 2017).

While 15 possible subunit dimer combinations have been identified, the most common dimer studied to date is the p65/p50 complex which has been well-documented to rapidly upregulate inflammatory cytokines  (Smale, 2012).  As of 2006, there were over 25,000 publications on the study of NF-kB (Gilmore, 2006), with many comprehensive and detailed reviews on the complex pathways, polymorphisms, and biological implications written prior to and since that time. Boston University Biology maintains a web site devoted to tracking the hundreds of genes identified as targets of NF-κB (  


List of the literature that was cited for this KE description. More help

Arancibia, S.A., Beltrán, C.J., Aguirre, I.M., Silva, P., Peralta, A.L., Malinarich, F., Hermoso, M.A., 2007. Toll-like receptors are key participants in innate immune responses. Biol. Res.

Bauernfeind, F.G., Horvath, G., Stutz, A., Alnemri, E.S., MacDonald, K., Speert, D., Fernandes-Alnemri, T., Wu, J., Monks, B.G., Fitzgerald, K.A., Hornung, V., Latz, E., 2009. NF-kB activating pattern recognition and cytokine receptors license NLRP3 inflammasome activation by regulating NLRP3 expression. J. Immunol. 183, 787.

Boaru, S.G., Borkham-Kamphorst, E., Van de Leur, E., Lehnen, E., Liedtke, C., Weiskirchen, R., 2015. NLRP3 inflammasome expression is driven by NF-κB in cultured hepatocytes. Biochem. Biophys. Res. Commun. 458, 700–706.

Carlsen, H., Alexander, G., Austenaa, L.M.I., Ebihara, K., Blomhoff, R., 2004. Molecular imaging of the transcription factor NF-kappaB, a primary regulator of  stress response. Mutat. Res. 551, 199–211.

Chen, C.C., Manning, A.M., 1995. Transcriptional regulation of endothelial cell adhesion molecules: a dominant role for NF-kappa B. Agents Actions. Suppl. 47, 135–141.

Cildir, G., Low, K.C., Tergaonkar, V., 2016. Noncanonical NF-κB Signaling in Health and Disease. Trends Mol. Med. 22, 414–429.

Dresselhaus, E.C., Meffert, M.K., 2019. Cellular Specificity of NF-kappa B Function in the Nervous System. Front. Immunol. 10.

Ernst, O., Vayttaden, S.J., Fraser, I.D.C., 2018. Measurement of NF-κB Activation in TLR-Activated Macrophages. Methods Mol. Biol. 1714, 67–78.

Espín-Palazón, R., Traver, D., 2016. The NF-κB family: Key players during embryonic development and HSC emergence. Exp. Hematol. 44, 519–527.

Gerondakis, S., Fulford, T.S., Messina, N.L., Grumont, R.J., 2014. NF-κB control of T cell development. Nat. Immunol. 15, 15–25.

Gilmore, T.D., 2006. Introduction to NF-κB: players, pathways, perspectives. Oncogene 25, 6680–6684.

Gilmore, T.D., Gerondakis, S., 2011. The c-Rel Transcription Factor in Development and Disease. Genes Gilmore TD, Gerondakis S c-Rel Transcr. Factor Dev. Dis. Genes Cancer 2695–711.cancer 2, 695–711.

Giridharan, S., Srinivasan, M., 2018. Mechanisms of NF-κB p65 and strategies for therapeutic manipulation. J. Inflamm. Res. 11, 407–419.

Graef, I.A., Gastier, J.M., Francke, U., Crabtree, G.R., 2001. Evolutionary relationships among Rel domains indicate functional diversification  by recombination. Proc. Natl. Acad. Sci. U. S. A. 98, 5740–5745.

Kaltschmidt, C., Greiner, J.F.W., Kaltschmidt, B., 2021. The Transcription Factor NF-κB in Stem Cells and Development. Cells 10.

Kelley, N., Jeltema, D., Duan, Y., He, Y., 2019. The NLRP3 Inflammasome: An Overview of Mechanisms of Activation and Regulation. Int. J. Mol. Sci. 20.

Li, Q., Verma, I.M., 2002. NF-κB regulation in the immune system. Nat. Rev. Immunol. 2, 725–734.

Maguire, O., O’Loughlin, K., Minderman, H., 2015. Simultaneous assessment of NF-κB/p65 phosphorylation and nuclear localization  using imaging flow cytometry. J. Immunol. Methods 423, 3–11.

Miraghazadeh, B., Cook, M.C., 2018. Nuclear Factor-kappaB in Autoimmunity: Man and Mouse. Front. Immunol. 9, 613.

Mussbacher, M., Salzmann, M., Brostjan, C., Hoesel, B., Schoergenhofer, C., Datler, H., Hohensinner, P., Basílio, J., Petzelbauer, P., Assinger, A., Schmid, J.A., 2019. Cell Type-Specific Roles of NF-κB Linking Inflammation and Thrombosis   . Front. Immunol.  .

Oeckinghaus, A., Ghosh, S., 2009. The NF-kappaB family of transcription factors and its regulation. Cold Spring Harb. Perspect. Biol. 1, a000034.

Osorio, F.G., de la Rosa, J., Freije, J.M., 2013. Luminescence-based in vivo monitoring of NF-κB activity through a gene delivery  approach. Cell Commun. Signal. 11, 19.

Pahl, H.L., 1999. Activators and target genes of Rel/NF-κB transcription factors. Oncogene 18, 6853–6866.

Ramaswami, S., Hayden, M.S., 2015. Electrophoretic mobility shift assay analysis of NF-κB DNA binding. Methods Mol. Biol. 1280, 3–13.

Ruiz-Perera, L.M., Schneider, L., Windmöller, B.A., Müller, J., Greiner, J.F.W., Kaltschmidt, C., Kaltschmidt, B., 2018. NF-κB p65 directs sex-specific neuroprotection in human neurons. Sci. Rep. 8, 16012.

Salminen, A., Kaarniranta, K., 2009. NF-κB Signaling in the Aging Process. J. Clin. Immunol. 29, 397–405.

Sen, R., Baltimore, D., 1986. Multiple nuclear factors interact with the immunoglobulin enhancer sequences. Cell 46, 705–716.

Smale, S.T., 2012. Dimer-specific regulatory mechanisms within the NF-κB family of transcription  factors. Immunol. Rev. 246, 193–204.

Sullivan, J.C., Wolenski, F.S., Reitzel, A.M., French, C.E., Traylor-Knowles, N., Gilmore, T.D., Finnerty, J.R., 2009. Two Alleles of NF-κB in the Sea Anemone Nematostella vectensis Are Widely Dispersed in Nature and Encode Proteins with Distinct Activities. PLoS One 4.

Sun, S.C., Chang, J.H., Jin, J., 2013. Regulation of nuclear factor-kappa B in autoimmunity. TRENDS Immunol. 34, 282–289. WE  - Science Citation Index Expanded (SCI-EXPANDED)

Tortola, L., Piattini, F., Hausmann, A., Ampenberger, F., Rosenwald, E., Heer, S., Hardt, W.-D., Rülicke, T., Kisielow, J., Kopf, M., 2022. KappaBle fluorescent reporter mice enable low-background single-cell detection of NF-κB transcriptional activity in vivo. Mucosal Immunol. 15, 656–667.

Villa, A., Gelosa, P., Castiglioni, L., Cimino, M., Rizzi, N., Pepe, G., Lolli, F., Marcello, E., Sironi, L., Vegeto, E., Maggi, A., 2018. Sex-Specific Features of Microglia from Adult Mice. Cell Rep. 23, 3501–3511.

Xia, Y., Shen, S., Verma, I.M., 2014. NF-κB, an active player in human cancers. Cancer Immunol. Res. 2, 823–830.

Ye, N., Ding, Y., Wild, C., Shen, Q., Zhou, J., 2014. Small molecule inhibitors targeting activator protein 1 (AP-1). J. Med. Chem. 57, 6930–6948.

Yu, H., Lin, L., Zhang, Z., Zhang, H., Hu, H., 2020. Targeting NF-κB pathway for the therapy of diseases: mechanism and clinical study. Signal Transduct. Target. Ther. 5, 209.

Zarei, A., Yang, C., Gibbs, J., Davis, J.L., Ballard, A., Zeng, R., Cox, L., Veis, D.J., 2019. Manipulation of the Alternative NF-κB Pathway in Mice Has Sexually Dimorphic  Effects on Bone. JBMR plus 3, 14–22.

Zhang, Q., Lenardo, M.J., Baltimore, D., 2017. 30 Years of NF-κB: A Blossoming of Relevance to Human Pathobiology. Cell 168, 37–57.

Zhang, T., Ma, C., Zhang, Z., Zhang, H., Hu, H., 2021. NF-kappa B signaling in inflammation and cancer. MEDCOMM 2, 618–653.

Zhong, H., May, M.J., Jimi, E., Ghosh, S., 2002. The phosphorylation status of nuclear NF-kappa B determines its association with  CBP/p300 or HDAC-1. Mol. Cell 9, 625–636.