| 1995 |
CHUK (IKK-alpha) was identified as a new protein containing a serine-threonine kinase catalytic domain at the N-terminus, a leucine zipper-like amphipathic alpha-helix in the middle, and a helix-loop-helix domain at the C-terminus, suggesting its kinase activity may be targeted to HLH and/or leucine zipper transcription factors. |
cDNA cloning and sequence analysis of murine CHUK |
Cellular & molecular biology research |
Medium |
8777433
|
| 1997 |
IKK-1 (IKK-alpha) and IKK-2 are components of a large multiprotein IkappaB kinase (IKK) signalsome complex purified from HeLa cells that phosphorylates IkappaB-alpha and IkappaB-beta in response to cytokine stimulation. Mutant IKK-2 affected RelA nuclear translocation and NF-kappaB-dependent reporter activity, establishing both kinases as essential for NF-kappaB activation. |
Biochemical purification of the IKK complex from HeLa cells, in vitro kinase assays phosphorylating IkappaB substrates, dominant-negative mutant analysis of NF-kappaB reporter activity |
Science (New York, N.Y.) |
High |
9346484
|
| 1998 |
NF-kappaB-inducing kinase (NIK) preferentially phosphorylates IKK-alpha over IKK-beta specifically on Ser-176 in the activation loop. A Ser-176-to-Ala mutant cannot be phosphorylated or activated by NIK and acts as a dominant negative inhibitor of IL-1- and TNF-induced NF-kappaB activation; a Ser-176-to-Glu mutant is constitutively active. |
In vitro kinase assay, site-directed mutagenesis (S176A and S176E), dominant-negative inhibition of NF-kappaB activation |
Proceedings of the National Academy of Sciences of the United States of America |
High |
9520446
|
| 1999 |
Both IKK-alpha and IKK-beta are activated by hematopoietic progenitor kinase-1 (HPK1) and MEKK1 stress response kinases. IKK-beta phosphorylated IkappaB constitutively in these assays whereas IKK-alpha was not active in the absence of cell stimulation, indicating differential basal activity. |
In vitro kinase assays, overexpression of HPK1 and MEKK1 upstream activators |
Oncogene |
Medium |
10523828
|
| 1999 |
IKK-1 (IKK-alpha) homodimer has dramatically lower catalytic efficiency toward IkappaB-alpha peptide substrates (k(cat)/K(m) ~0.02 h-1 uM-1) compared to IKK-2 (17.44 h-1 uM-1), while the IKK1/IKK2 heterodimer exhibits the highest catalytic efficiency (47.50 h-1 uM-1). The C-terminus of IkappaB-alpha activates the multisubunit IKK complex through subunits other than IKK-2. |
Recombinant protein expression (baculovirus), purification, and kinetic analysis of homodimers vs. heterodimer; peptide substrate kinetics |
The Journal of biological chemistry |
High |
10593898 10823818
|
| 2000 |
IKK1 and IKK2 double-knockout mouse embryo fibroblasts completely lack NF-kappaB activity in response to all tested inducers, and double-deficient embryos lose NF-kappaB-lacZ reporter expression in vascular endothelial cells, establishing that IKK1 and IKK2 are together essential for NF-kappaB activation in vivo. |
Genetic knockout (IKK1-/- / IKK2-/- double-deficient mice), NF-kappaB reporter (kappaB-lacZ transgene), MEF stimulation assays |
Genes & development |
High |
10898787
|
| 2002 |
IKK-alpha homodimers contain non-equivalent active sites: ADP and a peptide inhibitor show differential potency against IkappaBalpha phosphorylation vs. autophosphorylation reactions. The phosphorylation state of the activation loop (S176/S180) affects active site conformation, and autophosphorylation within the homodimer is intramolecular. |
Recombinant baculovirus-expressed homodimers, enzyme kinetics, inhibitor analysis, S176E/S180E mutant comparison |
Biochemical and biophysical research communications |
Medium |
12054687
|
| 2003 |
Vav-1 constitutively associates with IKK-alpha (but not IKK-beta) in Jurkat and primary CD4+ T cells via their helix-loop-helix domains. CD28 engagement increases Vav-1-associated IKK-alpha kinase activity, and both IKK-alpha and Vav-1 augment CD28-induced NF-kappaB activation. Vav-1 and IKK-alpha (but not IKK-beta) colocalize at the membrane upon CD28 stimulation. |
Co-immunoprecipitation, in vitro kinase assay, NF-kappaB reporter assay, confocal microscopy |
Journal of immunology (Baltimore, Md. : 1950) |
Medium |
12626540
|
| 2003 |
EBV LMP1 induces p100/NF-kappaB2 processing to p52 in human lymphoblasts via a NIK/IKKalpha-dependent and IKKbeta/IKKgamma-independent mechanism. IKKalpha knockout MEFs show loss of LMP1-induced MIG and CXCR4 upregulation, while IKKalpha absence hyperinduces MIP-2, TNF-alpha, and I-TAC, indicating IKKalpha's dual role in promoting noncanonical and downmodulating canonical NF-kappaB signaling. |
Genetic knockout MEFs (IKKalpha KO), dominant-negative IKK constructs, RNA expression analysis, NF-kappaB pathway dissection |
Proceedings of the National Academy of Sciences of the United States of America |
High |
14691250
|
| 2004 |
IKK-alpha has a dual NF-kappaB-dependent role (cusp formation) and an NF-kappaB-independent role (direction of epithelial invagination vs. evagination in incisor and whisker development) in tooth and ectodermal appendage development in mice. |
Ikkα mutant mouse analysis, genetic comparison with cIκBαΔN transgenic mice (NF-kappaB blocking), examination of Notch/Wnt/Shh pathway markers |
Developmental cell |
High |
14960276
|
| 2004 |
IKKalpha, IKKbeta, IKKepsilon, and TBK1 can all phosphorylate p65/RelA at Ser-536. IKKepsilon and TBK1 phosphorylate Ser-536 in vivo and in vitro. Importantly, IKKalpha/beta RNAi knockdown or IKKbeta inhibitor alone could not suppress Ser-536 phosphorylation, suggesting IKK-independent pathways also contribute. |
RNA interference, pharmacological inhibitors, chromatographic fractionation, in vitro kinase assay, reconstitution in p65-deficient fibroblasts |
The Journal of biological chemistry |
Medium |
15489227
|
| 2005 |
IKK1 (IKKalpha) knockout macrophages show enhanced NF-kappaB activity due to prolonged IkappaBalpha degradation after pathogen stimulation, caused by uncontrolled IKK2 kinase activity. This reveals IKK1 functions as a checkpoint to control IKK2-mediated IkappaBalpha phosphorylation in innate immunity. |
IKK1-/- embryonic liver-derived macrophages, NF-kappaB activity assay, IKK2 kinase assay, cytokine secretion measurement |
Proceedings of the National Academy of Sciences of the United States of America |
High |
16116086
|
| 2005 |
IKKalpha is required for RANK ligand-induced osteoclast formation in vitro but is not required in vivo for osteoclastogenesis, while IKKbeta is required both in vitro and in vivo. This establishes distinct and non-redundant roles for IKKalpha and IKKbeta downstream of RANK signaling. |
Conditional knockout mice (hematopoietic-specific), in vitro osteoclastogenesis assays, inflammation-induced bone loss model |
The Journal of experimental medicine |
High |
15897281
|
| 2006 |
IKKalpha regulates estrogen-induced cell cycle progression by controlling transcription of the E2F1 gene and E2F1-responsive genes. Estrogen treatment increases association of endogenous IKKalpha with E2F1 on E2F1-bound promoters, and IKKalpha potentiates p300/CBP-associated factor-mediated acetylation of E2F1. |
siRNA knockdown of IKKalpha, chromatin immunoprecipitation, Co-immunoprecipitation, gene expression analysis |
The Journal of biological chemistry |
Medium |
16407216
|
| 2006 |
p63 (TAp63 isoform) directly and indirectly transactivates IKKalpha and Ets-1, respectively, in a genetic pathway upstream of IKKalpha during epidermal development. DeltaNp63 upregulates IKKalpha indirectly through GATA-3. Genetic complementation in mice confirmed this p63→IKKalpha epistatic relationship. |
Molecular analyses (transcriptional assays), genetic complementation in mice, in vivo epistasis |
Journal of cell science |
High |
17093266
|
| 2007 |
ATM kinase phosphorylates IKK-alpha at Ser-473 in response to cisplatin treatment, causing nuclear accumulation of IKK-alpha, which then stabilizes p73 to promote apoptosis. IKKalpha-deficient MEFs show cisplatin-resistant phenotype. |
In vitro kinase assay (ATM phosphorylates IKK-alpha), site identification, immunofluorescence colocalization, IKKalpha-deficient MEF functional assay |
Oncogene |
Medium |
17700524
|
| 2007 |
IKK-alpha mediates chromatin modification on pro-inflammatory gene promoters in response to cigarette smoke: it phosphorylates histone H3 Ser-10 and promotes acetylation of H3 Lys-9 and RelA/p65 Lys-310, leading to sustained transcription of IL-6 and MIP-2. Dominant-negative IKK-alpha reduced CS-induced chromatin modification. |
Chromatin immunoprecipitation, gain-of-function overexpression, dominant-negative mutant transfection, in vivo mouse lung CS exposure |
American journal of respiratory cell and molecular biology |
Medium |
18239189
|
| 2007 |
NIK differentially regulates IKK-alpha-mediated activation of IRF3/7 vs. NF-kappaB: IKKalpha-S176E constitutively activates IRF3/7, while IKKalpha-S180E loses the ability to activate IRF3/7, demonstrating that the two NIK-phosphorylation sites on IKKalpha differentially govern its downstream effector functions. |
Site-directed mutagenesis (S176E, S180E), overexpression, IFN-alpha promoter reporter assay, NF-kappaB reporter assay |
Molecular immunology |
Medium |
18068231
|
| 2007 |
IKK1/IKKalpha and IKKbeta are both required for S. pneumoniae-induced MUC5AC mucin upregulation via an ERK1-dependent but IkappaBalpha-p65- and p100-p52-independent mechanism, revealing novel NF-kappaB-independent roles for IKKs in innate mucosal defense. |
Dominant-negative IKK constructs, siRNA knockdown, pathway inhibitors, ERK dependency assays, in vivo mouse model |
Journal of immunology (Baltimore, Md. : 1950) |
Medium |
17237423
|
| 2007 |
Keratinocyte-specific IKK1 ablation causes impaired epidermal-barrier function and increased transepidermal water loss due to defects in stratum corneum lipid composition and epidermal tight junctions, mediated by deregulation of retinoic acid receptor target genes. IKK1 is recruited to promoters of retinoic acid-regulated genes, indicating a role in RA-regulated transcription. |
Conditional knockout mice (keratinocyte-specific IKK1 ablation), barrier function assays, chromatin immunoprecipitation, retinoic acid-induced gene expression analysis |
Nature cell biology |
High |
17351639
|
| 2008 |
BAFF activates Akt and Erk in primary mouse B cells through BAFF-R in an IKK1-dependent manner, establishing IKK1 as a coordinator of multiple BAFF-R-mediated survival signaling pathways beyond NF-kappaB. |
IKK1 conditional knockout B cells, BAFF stimulation, Akt and Erk phosphorylation assays |
Proceedings of the National Academy of Sciences of the United States of America |
High |
18713867
|
| 2008 |
Combined conditional ablation of IKK1 and IKK2 (but not each alone) in hepatocytes sensitizes the liver to LPS/TNF-induced failure, revealing redundancy in canonical NF-kappaB signaling. Additionally, combined ablation of IKK1+IKK2 or IKK1+NEMO causes spontaneous fatal cholangitis involving IKK1-specific functions affecting the bile-blood barrier, revealing a novel IKK1-specific function in bile duct integrity. |
Conditional double-knockout mice (liver-specific), in vivo LPS challenge, histopathology |
Proceedings of the National Academy of Sciences of the United States of America |
High |
18606991
|
| 2008 |
IKKalpha/beta-phosphorylated IkappaBalpha plays a role in axon outgrowth and axon initial segment (AIS) development in hippocampal neurons. Inhibition of IkappaBalpha phosphorylation by IKKs impedes axon outgrowth and impairs localization of ankyrin G and voltage-gated sodium channels at the AIS. |
Pharmacological inhibition of IKK kinase activity in cultured hippocampal neurons, immunofluorescence for AIS markers |
Molecular and cellular neurosciences |
Low |
18321726
|
| 2010 |
The L. monocytogenes secreted protein InlC directly interacts with IKKalpha and impairs IkappaB phosphorylation and degradation normally induced by TNF-alpha, thus dampening host NF-kappaB-dependent innate immune responses during infection. |
Protein-protein interaction assay (direct binding), infection assays with WT vs. inlC-deletion mutant, cytokine measurement, mouse peritonitis model |
Proceedings of the National Academy of Sciences of the United States of America |
High |
20855622
|
| 2010 |
IKKalpha is necessary for TGFbeta-SMAD-mediated epithelial-mesenchymal transition (EMT) in Panc1 cells, independently of NF-kappaB. IKKalpha interacts with SMAD3 and controls SMAD complex formation on DNA to regulate transcription of SNAIL and SLUG genes. |
IKKalpha siRNA knockdown, Co-immunoprecipitation of IKKalpha with SMAD3, chromatin immunoprecipitation, gene expression analysis in Panc1 and MDA-MB231 cells |
Journal of cell science |
Medium |
21081648
|
| 2010 |
Loss of CHUK (IKKalpha) causes a lethal autosomal recessive fetal syndrome with severe craniofacial and limb malformations in humans, confirming IKKalpha is essential for skin epidermis and ectodermal derivative development. |
Human genetics (identification of point mutation), candidate-gene analysis, gene-expression arrays in affected fetuses |
The New England journal of medicine |
Medium |
20961246
|
| 2010 |
In zebrafish, the maternal effect gene poky/chuk/ikk1 is required for EVL differentiation via its kinase activity but not via its HLH domain, in contrast to the mouse where the HLH domain is important, demonstrating conservation of the requirement for Ikk1 in epidermal differentiation with divergent molecular mechanisms. |
Zebrafish genetic (poky mutant), kinase-dead and HLH-domain mutant rescue experiments, cell cycle and differentiation marker analysis |
Developmental biology |
Medium |
20692251
|
| 2011 |
Nuclear IKKalpha is present in resting CD4+ T cells and upon Th17 differentiation selectively associates with the Il17a gene locus to promote histone H3 phosphorylation and transcriptional activation of IL-17a in an NF-kappaB-independent manner. |
Chromatin immunoprecipitation (IKKalpha at Il17a locus), non-activatable IKKalpha knock-in T cells, Th17 differentiation assay, histone modification analysis |
The Journal of experimental medicine |
High |
21402739
|
| 2011 |
IKK1 inactivation in keratinocytes results in increased p63 expression and repression of Notch signaling. Forced expression of the Notch1 intracellular domain (NICD) partially rescues the differentiation defect of IKK1-/- keratinocytes, placing IKK1 upstream of Notch in epidermal differentiation. |
Ikk1 genetic inactivation in keratinocytes, NICD overexpression rescue, p63 RNAi knockdown, gene expression analysis |
The American journal of pathology |
Medium |
21435444
|
| 2013 |
IKKalpha acts independent of its kinase activity to drive chondrocyte hypertrophic differentiation. IKKalpha positively modulates ECM remodeling via multiple downstream targets including MMP-10 and TIMP-3, to maintain maximal MMP-13 collagenase activity. Differentiation of IKKalpha-deficient chondrocytes was rescued by a kinase-dead IKKalpha mutant. |
Cre-lox conditional IKKalpha knockout chondrocytes, kinase-dead mutant rescue, mRNA profiling, immunoblotting, MMP activity assays |
PloS one |
High |
24023802
|
| 2013 |
HCV via its 3' UTR interacts with DDX3X to activate IKK-alpha, which translocates to the nucleus and induces a CBP/p300-mediated transcriptional program involving SREBPs to upregulate lipogenic genes and enhance lipid droplet formation for viral assembly, independently of NF-kappaB. |
siRNA knockdown, chemical inhibitors of IKK-alpha, RNA-protein interaction, nuclear translocation assay, lipid droplet imaging, SREBP transcriptional assay |
Nature medicine |
High |
23708292
|
| 2014 |
Survivin-2B stabilizes IKK-alpha in the nucleus of NB4 cells; decreased survivin-2B leads to reduced nuclear IKK-alpha, which reduces P73 levels and consequently reduces UVRAG expression, switching protective autophagy to apoptosis. |
Co-immunoprecipitation (survivin-2B/IKK-alpha interaction in nucleus), nuclear fractionation, gene knockdown, in vivo tumor model |
Cell death & disease |
Medium |
24556686
|
| 2015 |
Upon HCV infection, DDX3X and IKK-alpha redistribute to stress granules (SGs) upon interaction with the HCV 3' UTR. Subsequently, IKK-alpha translocates to the nucleus while DDX3X and SG proteins redistribute to lipid droplet surfaces. Multiple HCV nonstructural proteins colocalize with DDX3X near SGs and LDs. |
Systematic imaging (live cell and fixed), biochemical fractionation, co-immunoprecipitation, siRNA knockdown of DDX3X and SG components |
Journal of virology |
Medium |
25740981
|
| 2016 |
X-ray crystal structure and cryo-EM structure of human IKK1 revealed dimeric and hexameric (trimer of dimers) forms. A surface critical for hexamer formation is essential for IKK1-dependent cellular p100-to-p52 processing (non-canonical NF-kappaB signaling), and this surface is divergent from IKK2, providing structural basis for distinct signaling by the two kinases. |
Single-particle cryo-EM, X-ray crystallography, mutagenesis of hexamer-forming surface, p100 processing assay in cells |
Cell reports |
High |
27851956
|
| 2016 |
RelB competes with the NIK:IKK1 complex for binding to a shared region of p100 within a transitional complex containing RelB, NIK, IKK1, and p100. This competition modulates the balance between p100 processing to p52 (generating active RelB:p52) and protection of p100 as part of the kappaBsome, controlling non-canonical NF-kappaB signaling output. |
Co-immunoprecipitation mapping interaction domains, p100 processing assays, analysis of kappaBsome formation |
Science signaling |
Medium |
27678221
|
| 2018 |
DCNL5 is directly phosphorylated by IKK-alpha (but not IKK-beta) on Ser-41 upon Toll-like receptor activation, identifying DCNL5 as a specific IKK-alpha substrate in innate immune signaling and the first DCNL member known to be regulated by kinase-mediated phosphorylation. |
In vitro kinase assay (IKKalpha vs. IKKbeta specificity), phosphorylation site mapping (S41), TLR stimulation assays |
PloS one |
Medium |
29958295
|
| 2018 |
IKK1/IKK2 double-deficient human cells (generated by CRISPR/Cas9n) show increased TNF-induced apoptosis mediated via RIPK1 in a predominantly apoptotic manner, independently of NF-kappaB RelA. Single IKK1 or IKK2 deficiency does not increase cell death, demonstrating a redundant, NF-kappaB-independent pro-survival function of the IKK complex. |
CRISPR/Cas9n knockout of IKK1, IKK2, IKK1/2 double, and RELA; caspase-3 activation, Annexin V binding, RIPK1 inhibition |
Biochimica et biophysica acta. Molecular cell research |
Medium |
29630899
|
| 2019 |
Inducible IKKalpha knockout in adult chondrocytes reduces cartilage degradation, collagenase activity, and hypertrophy-like features in the destabilization of medial meniscus (DMM) mouse model of post-traumatic OA, confirming an in vivo kinase-independent role for IKKalpha in OA-associated cartilage degradation. |
Tamoxifen-inducible conditional knockout (AcanCreERT2/+; IKKαf/f mice), DMM surgical OA model, histopathology, collagenase activity assays |
Scientific reports |
High |
31222033
|
| 2019 |
IKKalpha/CHUK acts as a tumor suppressor in lung epithelial cells: its loss in AT-II cells increases lung adenoma number and size after chemical carcinogen treatment, and IKKalpha knockdown in human NSCLC lines enhances xenograft tumor growth associated with upregulation of activated HIF-1alpha under hypoxia. |
Tamoxifen-inducible conditional IKKalpha knockout in AT-II cells, urethane carcinogenesis model, human NSCLC xenografts, transcriptome profiling, HIF-1alpha protein analysis |
Life science alliance |
High |
31792060
|
| 2021 |
IKK-alpha in lymphatic endothelial cells (LECs) is absolutely essential for lymph node formation, while IKK-alpha in hematopoietic cells (but not LECs) is required for mature B cell homeostasis. These two functions are mediated by distinct IKK-alpha-expressing cell populations. |
Tissue-specific conditional knockout mice (Tie2-cre, Cdh5-cre, LEC-specific Lyve1-cre, hematopoietic-specific), analysis of lymph node formation and B cell numbers |
Proceedings of the National Academy of Sciences of the United States of America |
High |
34810256
|
| 2021 |
NIK, by binding to IKK1, also associates with IKK2 and NEMO, allowing NIK to direct phosphorylation of IKK2 independently of IKK1's enzymatic function. IKK2 activation is maintained even when NIK's interaction with IKK1/NF-kappaB2 is compromised by specific NIK mutation, demonstrating that NIK-IKK1 and NIK-IKK2 activation pathways are not strictly coupled. |
NIK interaction-domain mutant knock-in mice, IKK1/IKK2 co-immunoprecipitation with NIK, NF-kappaB pathway activation assays |
Cell reports |
High |
41060807
|
| 2022 |
O-GlcNAc-modified NLRX1 interacts with IKK-alpha in M1 macrophages; elevated O-GlcNAcylation enhances the NLRX1/IKK-alpha interaction, and this enhanced interaction reduces IL-1beta expression, suggesting IKK-alpha is regulated by NLRX1 in a post-translational modification-dependent manner. |
Co-immunoprecipitation, confocal colocalization, ubiquitination assay, OGT inhibitor treatment, IL-1beta expression measurement |
In vitro cellular & developmental biology. Animal |
Low |
35513753
|