N4BP1 negatively regulates NF-κB by binding and inhibiting NEMO oligomerization
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ABSTRACT:
PROVIDER: PRJNA698568 | ENA |
REPOSITORIES: ENA
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Project description:Many immune responses depend upon activation of NF-κB, a key transcription factor in the elicitation of a cytokine response. Here we show that N4BP1 inhibits TLR-dependent activation of NF-κB by interacting with the NF-κB signaling essential modulator (NEMO, also known as IκB kinase γ) to attenuate NEMO-NEMO dimerization or oligomerization. The UBA-like (ubiquitin associated-like) and CUE-like (ubiquitin conjugation to ER degradation) domains in N4BP1 mediate the interaction with the NEMO COZI domain. Both in vitro and in mice, N4bp1 deficiency specifically enhances TRIF-independent (TLR2, TLR7, or TLR9-mediated), but not TRIF-dependent (TLR3 or TLR4-mediated), NF-κB activation leading to increased production of proinflammatory cytokines. In response to TLR4 or TLR3 activation, TRIF causes activation of caspase-8, which cleaves N4BP1 distal to residues D424 and D490 and abolishes its inhibitory effect. N4bp1-/- mice also exhibit diminished numbers of T cells in the peripheral blood. Our work identifies N4BP1 as an inhibitory checkpoint protein that must be overcome to activate NF-κB, and a TRIF-initiated caspase-8-dependent mechanism by which this is accomplished.
2021-02-08 | GSE165916 | GEO
Project description:The canonical NF-κB pathway is active in 70% of all pancreatic cancer cases and NF-κB Essential Modulator (NEMO) is essential for the activation of this pathway. In our study, we used KC mice, which express the oncogenic KRAS and develop precancerous lesions termed Pancreatic Intraepithelial Neoplasias (PanINs), and KNeC mice, which express the oncogenic KRAS and have NEMO deleted in their pancreatic cells. These mice were injected with cerulein to promote the development of pancreatitis (cerulein dosage= 50μg/kg). Cerulein was injected at 8 hourly intervals for 2 days in total. The first injection day was when mice reached their sixth week of age and the second injection day was 3 days after the first injection day. Both KC and KNeC mice developed PanINs. At the age of 10 months, pancreata of KC and KNeC mice were analyzed. Using laser capture microdissection, PanINs from both groups were excised and their transcriptome was analyzed though RNA-seq.
2024-03-13 | E-MTAB-12433 | biostudies-arrayexpress
Project description:We previously demonstrated that IKKα binds to and phosphorylates ATM thus potentiating the non-homologous end joining DNA damage repair pathway in cancer cells. Hence, inhibiting IKKα enhances the efficacy of DNA damage-based anticancer therapy. Whether additional elements contribute to this resistance-related mechanism remains unknown. We here show that NEMO physically interacts with the ATM-IKKα complex before damage. Upon exposure to damaging agents, NEMO is dispensable for ATM activation, but it is required to drive active ATM and IKKα to the sites of damage thus enabling DNA damage resolution. Recognition of damaged DNA by this IKKα/NEMO/ATM complex is partially mediated by direct interaction of NEMO to histones but highly dependent on PARP1 activity. Finally, we detected increased ATR activity in NEMO-deficient cells, and that ATR inhibition potentiates the effect of chemotherapy upon NEMO or IKKα depletion. Bioinformatic analysis of public CRC datasets support the functional impact of the IKKα/NEMO/ATM pathway in patient prognosis, which could be therapeutically exploited.
2024-02-11 | PXD043552 | Pride
Project description:Signalling through TNFR1 modulates proinflammatory gene transcription and programmed cell death, and its impairment causes autoimmune diseases and cancer. NEDD4 binding protein 1 (N4BP1) was recently identified as a critical suppressor of proinflammatory cytokine production1, whose mode of action remained unknown. Here, we show that N4BP1 is a novel linear ubiquitin receptor that negatively regulates NFB signalling by its unique dimerization-dependent ubiquitin-binding module. N4BP1 homo-oligomerization strategically positions two non-selective ubiquitin-binding domains, ensuring exclusive recognition of linear ubiquitin. Under proinflammatory conditions, N4BP1 is recruited to the nascent TNFR1 signalling complex where it, through linear ubiquitin binding, regulates stability of the TNFR1 signalling complex and duration of proinflammatory signalling. N4BP1 deficiency accelerates TNF-induced cell death by increasing complex II assembly. Under proapoptotic conditions, Caspase-8 mediates proteolytic processing of N4BP1 and the resulting cleavage fragment of N4BP1, which retains the ability to bind linear ubiquitin, is rapidly degraded by the 26S proteasome, accelerating apoptosis. In summary, our findings demonstrate that N4BP1 dimerization creates a unique linear ubiquitin reader that ensures timely and coordinated regulation of TNFR1-mediated inflammation and cell death.
2024-05-22 | PXD024355 | Pride
Project description:COVID-19 can damage cerebral small vessels and cause neurological symptoms. However, the vascular pathology and the potential mechanisms are unclear. In brains of SARS-CoV-2-infected patients and animal models, we found an increased number of empty basement membrane tubes, so-called string vessels representing remnants of lost capillaries. We obtained evidence that brain endothelial cells are infected and that the main protease of SARS-CoV-2 (Mpro) cleaves NEMO, the essential modulator of NF-κB. By ablating NEMO, Mpro induces the death of human brain endothelial cells and the occurrence of string vessels in mice. Deletion of receptor-interacting protein kinase (RIPK) 3, a mediator of regulated cell death, blocks the vessel rarefaction and disruption of the blood-brain barrier due to NEMO ablation. Importantly, a pharmacological inhibitor of RIPK signaling prevented the Mpro-induced microvascular pathology. Our data suggest RIPK as a potential therapeutic target to treat the neuropathology of COVID-19.
2021-07-31 | GSE180984 | GEO
Project description:Signal transduction by the NF-kappaB pathway is a key regulator of a host of cellular responses to extracellular and intracellular messages. The NEMO adaptor protein lies at the top of this pathway and serves as a molecular conduit, connecting signals transmitted from upstream sensors to the downstream NF-kappaB transcription factor and subsequent gene activation. The position of NEMO within this pathway makes it an attractive target from which to search for new proteins that link NF-kappaB signaling to additional pathways and upstream effectors. In this work, we have used protein microarrays to identify novel NEMO interactors. A total of 112 protein interactors were identified, with the most statistically significant hit being the canonical NEMO interactor IKKbeta, with IKKalpha also being identified. Of the novel interactors, more than 30% were kinases, while at least 25% were involved in signal transduction. Binding of NEMO to several interactors, including CALB1, CDK2, SAG, SENP2 and SYT1, was confirmed using GST pulldown assays and coimmunoprecipitation, validating the initial screening approach. Overexpression of CALB1, CDK2 and SAG was found to stimulate transcriptional activation by NF-kappaB, while SYT1 overexpression repressed TNFalpha-dependent NF-kappaB transcriptional activation in human embryonic kidney cells. Corresponding with this finding, RNA silencing of CDK2, SAG and SENP2 reduced NF-kappaB transcriptional activation, supporting a positive role for these proteins in the NF-kappaB pathway. The identification of a host of new NEMO interactors opens up new research opportunities to improve understanding of this essential cell signaling pathway. For microarray screening, Invitrogen Protoarray v4.0 protein microarrays were used. Human NEMO expressed as a C-terminal GST fusion was purified from E. coli lysates and labelled with biotin. NEMO or biotinylated GST were applied to the microarrays and binding partners detected using streptavidin-Alexa Fluor 647. Significant interactors on both arrays were detected using Invitrogen Protoarray Prospector software and a Z-score cutoff of 3.0. Following subtraction of interactors present on the GST control array, a final set of significant NEMO interactors was derived. Full experimental details are supplied in Fenner, B. J., Scannell, M. & Prehn, J. H. M. (2010). Expanding the substantial interactome of NEMO using protein microarrays. PLoS ONE (in press).
2010-06-19 | E-GEOD-19841 | biostudies-arrayexpress
Project description:Host defense and inflammation are regulated by the NF-kB essential modulator (NEMO), a scaffolding protein with a broad immune cell and tissue expression profile. Hypomorphic mutations in inhibitor of nuclear factor kappa B kinase regulatory subunit gamma (IKBKG) encoding NEMO typically present with immunodeficiency. Here we characterized a novel pediatric autoinflammatory syndrome in 3 unrelated male patients with distinct X-linked IKBKG germ-line mutations that led to overexpression of a NEMO protein isoform lacking the domain encoded by exon 5 (NEMO-Dex5). This isoform failed to associate with TANK binding kinase 1 (TBK1), and dermal fibroblasts from affected patients activated NF-kB in response to TNF, but not TLR3 or RIG-I-like-receptor (RLR) stimulation when isoform levels were high. By contrast, T cells, monocytes and macrophages that expressed NEMO-Dex5 exhibited increased NF-kB activation and IFN production, and blood cells from these patients expressed a strong interferon and NF-kB transcriptional signature. Immune cells and TNF-stimulated dermal fibroblasts upregulated the inducible IKK protein (IKKi) that was stabilized by NEMO-Dex5, promoting type I IFN induction and antiviral responses. These data reveal how IKBKG mutations that lead to alternative splicing of skipping exon 5 cause a clinical phenotype we name NEMO Deleted exon 5 Autoinflammatory Syndrome (NDAS), distinct from the immunodeficiency syndrome resulting from loss-of-function IKBKG mutations.
2023-05-17 | GSE196243 | GEO
Project description:Signal transduction by the NF-kappaB pathway is a key regulator of a host of cellular responses to extracellular and intracellular messages. The NEMO adaptor protein lies at the top of this pathway and serves as a molecular conduit, connecting signals transmitted from upstream sensors to the downstream NF-kappaB transcription factor and subsequent gene activation. The position of NEMO within this pathway makes it an attractive target from which to search for new proteins that link NF-kappaB signaling to additional pathways and upstream effectors. In this work, we have used protein microarrays to identify novel NEMO interactors. A total of 112 protein interactors were identified, with the most statistically significant hit being the canonical NEMO interactor IKKbeta, with IKKalpha also being identified. Of the novel interactors, more than 30% were kinases, while at least 25% were involved in signal transduction. Binding of NEMO to several interactors, including CALB1, CDK2, SAG, SENP2 and SYT1, was confirmed using GST pulldown assays and coimmunoprecipitation, validating the initial screening approach. Overexpression of CALB1, CDK2 and SAG was found to stimulate transcriptional activation by NF-kappaB, while SYT1 overexpression repressed TNFalpha-dependent NF-kappaB transcriptional activation in human embryonic kidney cells. Corresponding with this finding, RNA silencing of CDK2, SAG and SENP2 reduced NF-kappaB transcriptional activation, supporting a positive role for these proteins in the NF-kappaB pathway. The identification of a host of new NEMO interactors opens up new research opportunities to improve understanding of this essential cell signaling pathway.
2010-01-20 | GSE19841 | GEO
Project description:Experimental nephrotoxic serum nephritis (NTN) is a model for T-cell mediated human rapid progressive glomerulonephritis. T-cell receptor (TCR) stimulation leads to intracellular signaling events ultimately causing activation of transcription factors, such as NF-κB. Using CD4creIKK2fl/fl (CD4xIKK2Δ) and CD4creNEMOfl/fl (CD4xNEMOΔ) and CD4cre mice our results demonstrated that NTN was not attenuated in CD4xIKK2Δ, CD4xNEMOΔ when compared with CD4cre mice as showing no significant kidney functional difference with respect to BUN and proteinuria data as well as histological damage. Although the percentage of CD4+ T cells infiltrating kidneys was not significantly changed between the examined groups on day 10, further analysis showed significantly reduced Tregs and significant increase in Th1 and Th17 cells in CD4xIKK2Δ and CD4xNEMOΔ mice. The expression of renal cytokines and chemokines, IL-1β, CCL2 and CCL20, was significantly changed in CD4xIKK2Δ and CD4xNEMOΔ mice when compared with nephritic CD4cre animals. The microarray data confirmed the increased expression of Th17 related cytokines in splenetic CD4+ T cells. More importantly, our array data also demonstrated the interrupted canonical pathway in nephritic CD4xNEMOΔ mice, which highlighted the possible different downstream pathway when IKK2 or NEMO is specifically deleted in lymphocytes. By combining microarray gene expression and bioinformatics analyses our data have identified genes involved in T cell proliferation and differentiation that were differentially expressed between IKK2 and NEMO deficient CD4+ T cells. We propose that better understanding the role of IKK2 and NEMO in T cell regulation will help to recognize the role of IKK2 and NEMO kinase inhibitors in the clinical application in patients with glomerulonephritis.
2018-11-30 | GSE107364 | GEO
Project description:Using an unbiased RNA sequencing approach of primary CD4+ T cells infected with three wild type primary HIV-1 isolates and selective mutants thereof, Langer et al. show that the HIV-1 accessory protein Vpu exerts broad immunosuppressive effects, inhibiting the induction of innate and adaptive immune responses. Transcription factor network analyses reveal that Vpu suppresses the expression of NF‑κB rather than IRF3 target genes. As a result, Vpu impairs the production of pro-inflammatory cytokines such as IFNβ, CXCL10 and IL-6.
2019-02-05 | GSE117655 | GEO