Project description:Mutations in the core RNA splicing factor SF3B1 are prevalent in leukemias and uveal melanoma, but also recurrent in epithelial malignancies such as breast cancer. Whereas hotspot mutations in SF3B1 alter hematopoietic differentiation, whether SF3B1 mutations contribute to epithelial cancer development and progression is unknown. Here, we identify that SF3B1 mutations in mammary epithelial and breast cancer cells induce a recurrent pattern of aberrant splicing leading to activation of AKT and NF-kB, enhanced cell migration, and accelerated tumorigenesis. Transcriptomic analysis of human cancer specimens, MMTV-cre Sf3b1K700E/WT mice, and isogenic mutant cell lines identified hundreds of aberrant 3’ splice sites induced by mutant SF3B1, a portion of which were breast-specific. Across mouse and human tumors, mutant SF3B1 promoted aberrant splicing (dependent on aberrant branchpoints as well as pyrimidines downstream of the aberrant branchpoint) and consequent suppression of PPP2R5A and MAP3K7, critical negative regulators of AKT and NF-kB. Coordinate activation of NF-kB and AKT signaling was observed in the knock-in models, leading to accelerated cell migration and tumor development in combination with mutant PIK3CA but also hypersensitizing cells to AKT kinase inhibitors. These data identify mutations in SF3B1 as drivers of breast tumorigenesis and reveal unique vulnerabilities in cancers harboring them.
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: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: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: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: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: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