Project description:Chronic NF-kB activation in inflammation and cancer has long been linked to persistent activation of NF-kB–responsive gene promoters. However, NF-kB factors also massively bind to gene bodies. Here, we demonstrate that recruitment of the NF-kB factor RELA to intragenic regions regulates alternative splicing upon NF-kB activation by the viral oncogene Tax of HTLV-1. Integrative analyses of RNA splicing and chromatin occupancy, combined with chromatin tethering assays, demonstrate that DNA-bound RELA interacts with and recruits the splicing regulator DDX17, in an NF-kB activation–dependent manner. This leads to alternative splicing of target exons due to the RNA helicase activity of DDX17. Similar results were obtained upon Tax-independent NF-kB activation, indicating that Tax likely exacerbates a physiological process where RELA provides splice target specificity. Collectively, our results demonstrate a physical and direct involvement of NF-kB in alternative splicing regulation, which significantly revisits our knowledge of HTLV-1 pathogenesis and other NF-kB–related diseases.
Project description:The inhibitor of kB kinase (IKK) is the master regulator of the nuclear factor kB (NF-kB) pathway, involved in inflammatory, immune and apoptotic responses. In the ‘canonical’ NF-kB pathway, IKK phosphorylates inhibitor of kB (IkB) proteins and this triggers ubiquitin-mediated degradation of IkB, leading to release and nuclear translocation of NF-B transcription factors.
The data presented show that the IKK and IKK subunits recognize a YDDX docking site located within the disordered C-terminal region of IkBa. Our results also suggest that IKK contributes to the docking interaction with higher affinity as compared to IKK.
Project description:The bacterial product lipopolysaccharide (LPS) stimulates nuclear factor kB (NF-kB) signaling, which results in the production of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), as part of the immune response. NF-kB target genes also include those encoding proteins that inhibit NF-kB signaling through negative feedback loops. By simultaneously studying the dynamics of the nuclear translocation of the NF-kB subunit RelA and the activity of a Tnf-driven reporter in a mouse macrophage cell line, Sung et al. found that the gene encoding RelA was also a target of NF-kB. Synthesis of RelA occurred only at higher concentrations of LPS and constituted a positive feedback loop that dominated over existing negative feedback mechanisms. Genes expressed in response to a high concentration of LPS were enriched for those involved in innate immune responses. Together, these data suggest that the RelA-dependent positive feedback loop enables macrophages to mount an effective immune only above a critical concentration of LPS. Bone-marrow-derived macrophage (BMDM) cells were stimulated with zero, low, and high concentration of LPS separately for 4hrs. Two replicates for each condition.
Project description:The bacterial product lipopolysaccharide (LPS) stimulates nuclear factor kB (NF-kB) signaling, which results in the production of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), as part of the immune response. NF-kB target genes also include those encoding proteins that inhibit NF-kB signaling through negative feedback loops. By simultaneously studying the dynamics of the nuclear translocation of the NF-kB subunit RelA and the activity of a Tnf-driven reporter in a mouse macrophage cell line, Sung et al. found that the gene encoding RelA was also a target of NF-kB. Synthesis of RelA occurred only at higher concentrations of LPS and constituted a positive feedback loop that dominated over existing negative feedback mechanisms. Genes expressed in response to a high concentration of LPS were enriched for those involved in innate immune responses. Together, these data suggest that the RelA-dependent positive feedback loop enables macrophages to mount an effective immune only above a critical concentration of LPS.
Project description:Molecular cloning of a t(10;14)(q24;q32) from a B-cell lymphoma showed a recurrent breakpoint in homeobox NKX2-3 gene, which was highly expressed in comparison to non-expressing mature B lymphocytes. Epigenetically-mediated NKX2-3 over-expression was selectively found in patients with splenic marginal-zone lymphoma, MALT lymphoma and extranodal diffuse large-cell lymphoma. In young mice, restricted expression of NKX2-3 to lymphocytes activated multiple integrins (LFA-1, VLA-4, MAC-1), adhesion molecules (ICAM-1, MadCAM-1, L-selectin) and the chemokine receptor CXCR4 that enhanced their homing and migration to splenic tissues, whereby they were retained, progressively accumulating to form non-clonal tumors. At 18 months, B cells acquired genomic rearrangements and generated clonal B-cell lymphomas mirroring the spectrum of human NKX2-3-expressing tumors. Mouse and human lymphomas displaying NKX2-3 expression shared histopahological, genomic and molecular features, including canonical NF-KB activation. NF-KB inhibition reduced tumorigenecity of NKX2-3-positive lymphomas. Our study reveals that oncogenic NKX2-3 promotes B-cell lymphomagenesis by disturbing lymphocyte dynamics. Comparisson of global gene expression profiling between Emu-NKX2-3 transgenes mice and wild type mice.
Project description:A structure-function study of NF-kB subunit RelA and coactivator CBP/p300 interaction reveals the critical role of CBP/p300 in recruitment of RelA to its target promoter site.
Project description:Complemented carm1-/- MEFs with CARM1 wt were left untreated or were stimulated for 3hours with 10ng/ml mTNFa. mTNFa-induced NF-kB dependent gene expression was analyzed on a custom array for specific NF-kB target genes
Project description:Constitutive activation of the nuclear factor-kappa B (NF-kB) pathway is a hallmark of the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL). Recurrent mutations of NF-kB regulators that cause constitutive activity of this oncogenic pathway have been identified. However, it remains unclear how specific target genes are regulated. We identified the IkB-like protein NFKBIZ that binds NF-kB subunits and enhances transactivation of some NF-kB target genes while repressing others, to be upregulated in ACB compared to GCB DLBCL primary patient samples (p=5.1 x 10^-37). Knockdown of NFKBIZ by RNA interference was toxic to ABC but not GCB DLBCL cell lines. Gene expression profiling following NFKBIZ knockdown significantly downregulated a large number of NF-kB target genes, suggesting a central role in regulating NF-kB signaling. To further investigate the molecular mechanisms of how NFKBIZ mediates NF-kB signaling in ABC DLBCL, we performed immunoprecipitations and detected an interaction of NFKBIZ with both p50 and p52 NF-kB subunits, indicating that both the canonical and non-canonical NF-kB pathways are regulated by NFKBIZ. Collectively, our data imply that NFKBIZ is required for NF-kB signaling in ABC DLBCL and thus might represent a promising molecular target for future therapies. The complete dataset is comprised of three experiments with the male HBL-1 ABC DLBCL cell line: a) 8 paired GEP measurements after NFKBIZ inhibition by shRNA, b) 6 paired GEP measurements after applying the MLN inhibitor and c) 4 two-color measurements after applying a MALT inhibitor. This dataset includes 8 paired GEP measurements after NFKBIZ inhibition by shRNA.