Overexpression of IκB⍺ modulates NF-κB activation of inflammatory target gene expression
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ABSTRACT:
PROVIDER: PRJNA950104 | ENA |
REPOSITORIES: ENA
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Project description:Cells respond to inflammatory stimuli such as cytokines by activation of the nuclear factor-κB (NF-κB) signalling pathway, resulting in oscillatory translocation of the transcription factor p65 between nucleus and cytoplasm to mediate immune response. We investigate the relationship between p65 and inhibitor-κB⍺ (IκBα) protein levels and dynamic properties of the system, and how this interaction impacts on the expression of key inflammatory genes. Using bacterial artificial chromosomes, we developed new cell models of IκB⍺-eGFP protein overexpression in a native genomic context. We find that cells with high levels of the negative regulator IκBα remain responsive to inflammatory stimuli and maintain dynamics for both p65 and IκBα. In contrast, canonical target gene expression is dramatically reduced by overexpression of IκBα, but can be partially rescued by overexpression of p65. Treatment with leptomycin B to promote nuclear accumulation of IκB⍺ also suppresses canonical target gene expression, suggesting a mechanism in which nuclear IκB⍺ accumulation prevents productive p65 interaction with promoter binding sites. This causes reduced target promoter binding and gene transcription, which we validate by chromatin immune precipitation and in primary cells. Overall, we show how inflammatory gene transcription is modulated by the expression levels of both IκB⍺ and p65, and that transcription can be partially decoupled from p65 protein dynamics. This results in an anti-inflammatory effect on transcription, demonstrating a broad mechanism to modulate the strength of inflammatory response. https://doi.org/10.1101/2023.03.14.532132
2023-03-30 | GSE228526 | GEO
Project description:Cells respond to inflammatory stimuli such as cytokines by activation of the nuclear factor-κB (NF-κB) signalling pathway, resulting in oscillatory translocation of the transcription factor p65 between nucleus and cytoplasm in some cell types. We investigate the relationship between p65 and inhibitor-κB⍺ (IκBα) protein levels and dynamic properties of the system, and how this interaction impacts on the expression of key inflammatory genes. Using bacterial artificial chromosomes, we developed new cell models of IκB⍺-eGFP protein overexpression in a pseudo-native genomic context. We find that cells with high levels of the negative regulator IκBα remain responsive to inflammatory stimuli and maintain dynamics for both p65 and IκBα. In contrast, canonical target gene expression is dramatically reduced by overexpression of IκBα, but can be partially rescued by overexpression of p65. Treatment with leptomycin B to promote nuclear accumulation of IκB⍺ also suppresses canonical target gene expression, suggesting a mechanism in which nuclear IκB⍺ accumulation prevents productive p65 interaction with promoter binding sites. This causes reduced target promoter binding and gene transcription, which we validate by chromatin immunoprecipitation and in primary cells. Overall, we show how inflammatory gene transcription is modulated by the expression levels of both IκB⍺ and p65. This results in an anti-inflammatory effect on transcription, demonstrating a broad mechanism to modulate the strength of inflammatory response.
| S-EPMC10203502 | biostudies-literature
Project description:Hematopoietic aging is characterized by chronic inflammation associated with myeloid bias, hematopoietic stem cell (HSC) accumulation, and functional HSC impairment. Yet it remains unclear how inflammation promotes aging phenotypes. Nuclear factor κB (NF-κB) both responds to and directs inflammation, and we present an experimental model of elevated NF-κB activity ("inhibitor of κB deficient" [IκB-]) to dissect its role in hematopoietic aging phenotypes. We find that while elevated NF-κB activity is not sufficient for HSC accumulation, HSC-autonomous NF-κB activity impairs their functionality, leading to reduced bone marrow reconstitution. In contrast, myeloid bias is driven by the IκB- proinflammatory bone marrow milieu, as observed functionally, epigenomically, and transcriptomically. A single-cell RNA sequencing (scRNA-seq) HSPC labeling framework enables comparisons with aged murine and human HSC datasets, documenting an association between HSC-intrinsic NF-κB activity and quiescence but not myeloid bias. These findings delineate separate regulatory mechanisms that underlie the three hallmarks of hematopoietic aging, suggesting that they are specifically and independently therapeutically targetable.
2025-08-25 | GSE264569 | GEO
Project description:Hematopoietic aging is characterized by chronic inflammation associated with myeloid bias, hematopoietic stem cell (HSC) accumulation, and functional HSC impairment. Yet it remains unclear how inflammation promotes aging phenotypes. Nuclear factor κB (NF-κB) both responds to and directs inflammation, and we present an experimental model of elevated NF-κB activity (“inhibitor of κB deficient” [IκB–]) to dissect its role in hematopoietic aging phenotypes. We find that while elevated NF-κB activity is not sufficient for HSC accumulation, HSC-autonomous NF-κB activity impairs their functionality, leading to reduced bone marrow reconstitution. In contrast, myeloid bias is driven by the IκB– proinflammatory bone marrow milieu, as observed functionally, epigenomically, and transcriptomically. A single-cell RNA sequencing (scRNA-seq) HSPC labeling framework enables comparisons with aged murine and human HSC datasets, documenting an association between HSC-intrinsic NF-κB activity and quiescence but not myeloid bias. These findings delineate separate regulatory mechanisms that underlie the three hallmarks of hematopoietic aging, suggesting that they are specifically and independently therapeutically targetable.
2025-08-21 | GSE261946 | GEO
Project description:T cell acute lymphoblastic leukemia (T-ALL), unlike other ALL types, is only infrequently associated with chromosomal aberrations, but it was recently shown that the majority of TALL patients carry activating mutations in the NOTCH1 gene. However, the signaling pathways and target genes responsible for Notch1-induced neoplastic transformation remain undefined. We report here that constitutively-active Notch1 activates the NF-κB pathway transcriptionally and via the IκB kinase (IKK) complex, thereby causing increased expression of multiple well-characterized NF-κB target genes in bone marrow hematopoietic stem cells and progenitors. Our observations demonstrate that the NF-κB pathway is highly active in established human T-ALL and that inhibition of the pathway can efficiently restrict tumor growth both in vitro and in vivo. These studies identify NF-κB as one of the major mediators of NOTCH1-induced transformation and suggest that the NF-κB pathway is a potential target of future targeted therapies of T-ALL. Keywords: gene expression analysis, signaling pathway alteration
2006-12-02 | GSE6396 | GEO
Project description:Gastric mucosa responds to the pathogen Helicobacter pylori (H. pylori) by producing and release of pro-inflammatory cytokines that activate the innate immune system mainly through activation of the transcription factor NF-κB. Although NF-κB signaling is well studied for many possible inducers, induction by H. pylori remains poorly understood. Here, we performed a high-throughput genome-wide RNAi screen for genes influencing H. pylori-induced NF-κB activation. In comparison to TNFα or IL‐1β NF‐κB signaling, we identified 21 proteins unique necessary for H. pylori NF-κB pathway and 24 factors that inhibited the activation. Furthermore, we present here the R/Bioconductor package Nested Effect Model for systematic use in high-throughput screens to classify newly identified factors. We identified alpha kinase 1 (ALPK1) as particular important for the H. pylori NF‐κB pathway without affecting TNFα or IL‐1β signaling. ALPK1 silencing inhibits activity of TAK1 and the IκB kinases (IKKs), degradation of the NF‐κB inhibitor IκBα, nuclear translocation of the NF‐κB subunit p65, and transcription of the NF‐κB target genes, e.g. IL‐8. Thus, we identify ALPK1 as a novel inflammatory regulator functioning particularly in the NF‐κB signaling network activated by H. pylori.
2019-09-02 | GSE89613 | GEO
Project description:Cordyceps participates in various pharmacological activities including anti-tumor, and is involved in the regulation of NF-κB signaling pathway. However, the detailed role of cordycepin in suppression of NF-κB signaling pathway is less clear. In this study, we first analyzed the effect of cordyceps on NF-κB activity in TK-10 cells, and found that cordyceps resulted in a dose-dependent reduction in TNF-α-induced NF-κB activation. Here, we show that cordyceps mediated NF-kB inhibition induces apoptosis in TK-10 cells involved the serial activation of caspases. Moreover, we demonstrate that in addition to activating caspases, the cordyceps negatively modulates TNF-α-mediated NF-κB signaling to promote JNK activation, which results in apoptosis, and that NF-kB regulates antiapoptotic factor GADD45b and the JNK kinase MKK7. When the TNFα cytokine binds to the TNF receptor, IκB dissociates from NF-κB. As a result, the active NF-κB translocates to the nucleus. Cordyceps clearly prevented NF-κB from mobilizing to the nucleus, resulting in downregulation of GADD45b, whereas upregulation of MKK7 and phosphorylation of JNK (p-JNK). This increased Bax activation, leading to marked cordyceps-induced apoptosis. Bax subfamily proteins induced apoptosis through caspase-3. Furthermore, siRNA mediated inhibition of MKK7 downregulated p-JNK and The JNK inhibitor SP600125 strongly inhibited Bax. Thus, these results indicate that cordyceps inhibits NF-κB/GADD45b signaling activation to upregulate MKK7-JNK signaling pathway to induce apoptosis in TK-10 cells and support the potential of cordyceps as a therapeutic agent for renal cancer.
2016-05-24 | GSE81728 | GEO
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:Chronic lymphocytic leukemia (CLL) is a disease with a highly variable prognosis. The clinical course can however be predicted thanks to prognostic markers. Poor prognosis is associated with expression of a B cell receptor (BCR) from unmutated immunoglobulin variable heavy-chain genes (IgVH) and expression of zeta associated protein of 70 kDa (ZAP-70). The reason why ZAP-70 expression is associated with poor prognosis and whether the protein has a direct pathogenic function is at present unknown. By transfer of ZAP-70 to CLL cells, we show here that expression of ZAP-70 in CLL cells leads to increased expression of the NF-κB target genes interleukin-1β (IL-1β), IL-6 and IL-8 upon BCR triggering. This could be blocked by inhibition of NF-κB signaling through inhibition of IκB kinases (IKK). Transcriptome analysis identified a NF-κB RelA signature imposed by ZAP-70 expression in BCR stimulated CLL cells. We conclude that ZAP-70 acts directly as an amplifier of NF-κB signaling in CLL cells which could be an underlying mechanism for its association with poor prognosis and which may represent a therapeutic target.
2013-10-22 | GSE51286 | GEO
Project description:Non-consensus binding sites of transcription factors are often observed within the promoters and enhancers of various genes; however, their effect on transcriptional strength is unclear. Within the promoters and enhancers of NF-κB-responsive genes, we identified clusters of non- consensus κB DNA sites, many exhibiting low affinity for NF-κB in vitro. Deletion of these sites demonstrated their collective critical role in transcription. We explored how these “weak” κB sites exert their influence, especially given the typically low nuclear concentration of NF-κB. Using proteomics approaches, we identified additional nuclear factors, including other DNA-binding TFs, that could interact with κB site-bound NF-κB RelA without their direct interaction to DNA. ChIP- seq and RNA-seq analyses suggest that these accessory TFs, referred to as the TF-cofactors of NF-κB, facilitate dynamic recruitment of NF-κB to the clustered κB sites. Overall, the occupancy of NF-κB at promoters and enhancers appears to be defined by a collective contribution from all κB sites, both weak and strong, in association with specific cofactors. This congregation of multiple factors within dynamic transcriptional complexes is likely a common feature of transcriptional programs.
2025-10-13 | PXD065004 | Pride