Project description:Notch dependent gene expression in T6E cell line Transcription profiles of Notch signaling active, inactive and recovered were compared
Project description:Activating mutations in the gene encoding the cell-cell contact signaling protein Notch1 are common in human T cell acute lymphoblastic leukemias (T-ALLs). However, expressing Notch1 mutant alleles in mice fails to efficiently induce the development of leukemia. We performed a gain-of-function screen to identify proteins that enhanced signaling by leukemia-associated Notch1 mutants. The transcription factors MAFB and ETS2 emerged as candidates that individually enhanced Notch1 signaling, and when coexpressed, they synergistically increased signaling to an extent similar to that induced by core components of the Notch transcriptional complex. In mouse models of T-ALL, MAFB enhanced leukemogenesis by the naturally occurring Notch1 mutants, decreased disease latency, and increased disease penetrance. Decreasing MAFB abundance in mouse and human T-ALL cells reduced the expression of Notch1 target genes, including MYC and HES1, and sustained MAFB knockdown impaired T-ALL growth in a competitive setting. MAFB bound to ETS2 and interacted with the acetyltransferases PCAF and P300, highlighting its importance in recruiting coactivators that enhance Notch1 signaling. Together, these data identify a mechanism for enhancing the oncogenic potential of weak Notch1 mutants in leukemia models, and they reveal the MAFB-ETS2 transcriptional axis as a potential therapeutic target in T-ALL.
Project description:MafA and MafB transcription factors have been shown to be key regulators of insulin and glucagon transcription. MafB is essential for alpha and beta cell differentiation, as MafB deficient mice produced fewer insulin+ and glucagon+ cells during development, with MafA expressed in remaining insulin+ cells. In contrast, beta cell development was reported to be normal in a total MafA knock out, although the animals developed beta cell dysfunction and diabetes as adults. However, we have found that MafB expression is elevated during development and retained in adult insulin+ cells after conditional removal of MafA in the pancreas. These studies will evaluate the broader significance of these insulin and glucagon regulators in alpha and beta cell development and function. Our efforts will focus on determining if the concerted actions of MafA and MafB factors are significant to beta cell formation, and we specifically plan to: Determine how alpha and beta cell differentiation is affected in MafA/MafB compound mutant mice during pancreas development. cDNA microarray studies (pancchip 6.0) with wild type, MafAKO, MafB-/-, and MafAKOMafB-/- mutant E18.5 pancreata will be performed to comprehensively identify genes controlled by MafA and MafB in developing alpha and beta cells.
Project description:MafB is a member of the large Maf family of transcription factors that share similar basic region/leucine zipper DNA binding motifs and N-terminal activation domains.Although it is well known that MafB is specifically expressed in macrophages, characterization of the null mutant phenotype in these tissues has not been previously reported. To investigate suspected MafB functions macrophages, we generated mafB/green fluorescent protein (GFP) knock-in null mutant mice. MafB deficiency was found to dramatically suppress F4/80 expression in nonadherent macrophages. To investigate detail function of MafB in nonadherent macrophages, we performed microarray analysis. Macrophages were derived from day 14.5 fetal livers of mafB- /- and WT mice. Suspensions of single fetal liver cells were prepared by mechanical disruption . A total of 106 cells in suspension were centrifuged at 1,200 rpm for 5 min, and the cell pellet was resuspended in Dulbeccoâs modified Eagleâs medium supplemented with 10% fetal calf serum (heat inactivated), streptomycin and penicillin (100 units/ml), and macrophage colony-stimulating factor (M-CSF) (10 ng/ml) and then seeded either onto a nonadhesive dishes coated with hydrophilic polymers (Hydrocell; Cell Seed, Tokyo). The culture medium was not changed throughout the experiment. M-CSF (final concentration, 10 ng/ml) was added every day from day 4 onwards. One, 2, 4, and 6 days after seeding, the cells were harvested and analyzed by flow cytometry. After 6 day culture, macrophages of Mafb-/- and WT were use microarray analysis .
Project description:MafB is a member of the large Maf family of transcription factors that share similar basic region/leucine zipper DNA binding motifs and N-terminal activation domains.Although it is well known that MafB is specifically expressed in macrophages, characterization of the null mutant phenotype in these tissues has not been previously reported. To investigate suspected MafB functions macrophages, we generated mafB/green fluorescent protein (GFP) knock-in null mutant mice. MafB deficiency was found to dramatically suppress F4/80 expression in nonadherent macrophages. To investigate detail function of MafB in nonadherent macrophages, we performed microarray analysis.
Project description:Purpose: To investigate the impact of oncogenic Notch on the 3D genome organization of cancer cells. Methods: We generated cohesin HiChIP and 1D epigenomic data sets in two different Notch-dependent cancer cell types, triple-negative breast cancer (TNBC) and mantle cell lymphoma (MCL), in the Notch-on and -off states. Results: We report here that Notch transcription complexes control their direct target genes through two distinct regulatory modes: either through existing loops or by facilitating new long-range regulatory interactions. This combination of pre-existing and Notch-promoted loops coalesce enhancers and promoters to form highly interacting clusters, termed “3D cliques”. Notch preferentially activates enhancers and promotes looping interactions within highly connected 3D cliques that regulate key oncogenes. Conclusions: These observations suggest a general mechanism that oncogenic transcription factors can exploit to regulate the transcriptional outputs of cancer cells.