Project description:The nuclear factor kB (NF-kB) subunits RelA, RelB, c-Rel, p50 and p52 are each critical for B-cell development and function. To systematically characterize their responses to canonical and non-canonical NF-kB pathways activity, we performed ChIP-seq analysis in lymphoblastoid B-cells. We found a surprisingly complex NF-kB binding landscape, which did not readily reflect the two NF-kB pathway paradigm. Instead, ten subunit binding patterns were observed at promoters and eleven at enhancers. Surprisingly, nearly one-third of NF-kB binding sites lacked kB motifs. De novo motif finding uncovered distinct modes of NF-kB recruitment at these sites. The oncogenic forkhead box protein FOXM1 and NF-kB co-occupied many kB sites despite the absence of a FOXM1 DNA motif. FoxM1 knockdown decreased expression of key NF-kB targets and caused apoptosis. Our study highlights opportunities for selective therapeutic NF-kB blockade. ChIP-seq was used to define the genomic landscape of NF-kB DNA binding in lymphoblastoid cells.
Project description:Abstract. Deregulated c-MYC is found in a variety of cancers where it promotes proliferation as well as apoptosis. In many hematological malignancies enhanced NF-kB exerts prosurvival functions. Here we investigated the role of NF-kB in mouse and human c-MYC-transformed lymphomas. The NF-kB-pathway is extinguished in murine lymphoma cells and extrinsic stimuli typically inducing NF-kB activity fail to activate this pathway. Genetic activation of the NF-kB pathway induces apoptosis in these cells, while inhibition of NF-kB by an IkBa superrepressor provides a selective advantage in vivo. Furthermore, in human Burkitt´s lymphoma cells we find that NF-kB activation induces apoptosis. NF-kB upregulates Fas and predisposes to Fas-induced cell death, which is caspase 8 mediated and can be prevented by CFLAR overexpression. We conclude that c-MYC overexpression sensitizes cells to NF-kB-induced apoptosis and persistent inacvtivity of NF-kB signaling is a prerequisite for MYC-mediated tumorigenesis. We could also show that low immunogenicity and Fas insensitivity of MYC driven lymphoma cells is reversed by activation of NF-kB. Our observations provide a molecular explanation for the described absence of the NF-kB signaling in Burkitt´s lymphoma and question the applicability of NF-kB inhibitors as candidates for treatment of this cancer.
Project description:The nuclear factor kB (NF-kB) subunits RelA, RelB, c-Rel, p50 and p52 are each critical for B-cell development and function. To systematically characterize their responses to canonical and non-canonical NF-kB pathways activity, we performed ChIP-seq analysis in lymphoblastoid B-cells. We found a surprisingly complex NF-kB binding landscape, which did not readily reflect the two NF-kB pathway paradigm. Instead, ten subunit binding patterns were observed at promoters and eleven at enhancers. Surprisingly, nearly one-third of NF-kB binding sites lacked kB motifs. De novo motif finding uncovered distinct modes of NF-kB recruitment at these sites. The oncogenic forkhead box protein FOXM1 and NF-kB co-occupied many kB sites despite the absence of a FOXM1 DNA motif. FoxM1 knockdown decreased expression of key NF-kB targets and caused apoptosis. Our study highlights opportunities for selective therapeutic NF-kB blockade.
Project description:To address the role of NF-kB in aging in vivo, we utilized a well-characterized system that allows inducible and site-specific inhibition of NF-kB activity in murine skin. The hormone binding domain of the mutant estrogen receptor that is responsive to 4-hydroxytamoxifen (4-OHT) was fused to a mutant of p50 (IDNkB, inducible dominant negative NF-kB) that dimerizes with other NF-kB subunits but is unable to bind DNA, thus dominantly inhibiting NF-kB activity. Expression was driven within the basal layer of murine epidermis by the keratin 14 promoter in transgenic mice. To test whether NF-kB activity is required to maintain age-associated gene expression, we applied topical 4-OHT and ethanol vehicle (EtOH) for two weeks to the right (R) and left (L) dorsal flanks, respectively, of chronologically aged transgenic mice (O, 18-23 months). Young transgenic mice (Y, 1 month) were treated in parallel as control. Skin samples were harvested and analyzed for gene expression using mouse cDNA microarrays containing 35,217 elements, representing 18,880 unique genes. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set Computed
Project description:To address the role of NF-kB in aging in vivo, we utilized a well-characterized system that allows inducible and site-specific inhibition of NF-kB activity in murine skin. The hormone binding domain of the mutant estrogen receptor that is responsive to 4-hydroxytamoxifen (4-OHT) was fused to a mutant of p50 (IDNkB, inducible dominant negative NF-kB) that dimerizes with other NF-kB subunits but is unable to bind DNA, thus dominantly inhibiting NF-kB activity. Expression was driven within the basal layer of murine epidermis by the keratin 14 promoter in transgenic mice. To test whether NF-kB activity is required to maintain age-associated gene expression, we applied topical 4-OHT and ethanol vehicle (EtOH) for two weeks to the right (R) and left (L) dorsal flanks, respectively, of chronologically aged transgenic mice (O, 18-23 months). Young transgenic mice (Y, 1 month) were treated in parallel as control. Skin samples were harvested and analyzed for gene expression using mouse cDNA microarrays containing 35,217 elements, representing 18,880 unique genes. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:Stringent regulation of TNF signaling prevents aberrant inflammation. TNF engages the canonical NF-kB pathway for activating the RelA:p50 heterodimer, which mediates specific expressions of pro-inflammatory and immune response genes. Importantly, the NF-kB system discriminates between time-varied TNF inputs. Negative feedback regulators of the canonical pathway, including IkBa, thought to ensure transient RelA:p50 responses to brief TNF stimulations. The noncanonical NF-kB pathway controls a separate RelB activity associated with immune differentiation. In a systems modeling approach, we uncovered an unexpected role of p100, a constituent of the noncanonical pathway, in TNF signaling. Brief TNF stimulation of p100-deficient cells produced an additional late NF-kB activity composed of the RelB:p50 heterodimer, which distorted the TNF-induced gene-expression program. Periodic TNF pulses augmented this RelB:p50 activity, which was reinforced by NF-kB-dependent RelB synthesis. In sum, the NF-kB system seems to engage distantly related molecular species for enforcing dynamical and gene controls of immune-activating TNF signaling.
Project description:2 This project is to identify the potential neddylation sites in human NF-kB inducing kinase (A.k.a. Map3K14). NIK-HA or NIK-HA in combination with FLAG-NEDD8 were co-expressed in HEK293T cells. NIK-HA were pulled down via denaturing immunoprecipitation protocol, subject to SDS-PAGE, in-gel trypsin digestion, and Nano LC-MS/MS Analysis. The potential peptides containing K-GG sites were identified.
Project description:The ability of dendritic cells (DC) to initiate immunity and induce antigen-specific tolerance makes DC ideal targets for pharmacological intervention into immune responses. NF-kB factors are a family of transcriptional regulators important for DC development and function. However, the identity of NF-kB target genes that are central to DC biology is largely unknown. In the present study IkBa super repressor (IkBa-SR) and DNA microarray analysis were used to determine the repertoire of NF-kB responsive genes in DC. In DC these genes regulate vital DC functions of antigen uptake and presentation, motility, survival, etc. Taking in account limitations of the genome-wide microarray analysis, generated transcription factor data were confirmed by the independent means of RT-PCR and chromatin immunoprecipitation. Kinetics of NF-kB induction by well-known DC activatory agents TNFa and LPS were further analysed. NF-kB regulated genes can be potentially useful targets for the development of more specific anti-inflammatory agents for clinical applications. Keywords: drug treatment, adenovirus transduction
Project description:A subtype of diffuse large B-cell lymphoma (DLBCL), termed activated B-cell-like (ABC) DLBCL, depends on constitutive NF-kB pathway signaling for survival. Small molecule inhibitors of IkB kinase b (IKKb), a key regulator of the NF-kB pathway, kill ABC DLBCL cells and hold promise for the treatment of this lymphoma type. We conducted an RNA interference genetic screen to investigate potential mechanisms of resistance of ABC DLBCL cells to IKKb inhibitors. We screened a library of small hairpin RNAs (shRNAs) targeting 500 protein kinases for shRNAs that would kill an ABC DLBCL cell line in the presence of a small molecule IKKb inhibitor more effectively than in its absence. Two independent shRNAs targeting IKKa synergized with the IKKb inhibitor to kill three different ABC DLBCL cell lines but were not toxic by themselves. Surprisingly, IKKa shRNAs blocked the classical rather than the alternative NF-kB pathway in ABC DLBCL cells, as judged by inhibition of IkBa phosphorylation. IKKa shRNA toxicity was reversed by coexpression of wild type but not kinase inactive forms of IKKa, suggesting that IKKa may directly phosphorylate IkBa under conditions of IKKb inhibition. These results suggest that therapy for ABC DLBCL may be improved by targeting both IKKa and IKKb. Keywords: compound treatment design Gene expression profiling of OCI-Ly3 cells with or without expressing IKKa shRNA in the presence or absence of 12.5 uM IKKb inhibitor for 2 and 3 days. Four samples were analyzed.