Project description:SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes displace nucleosomes to promote the access of transcription factors to enhancers and promoters. Despite the critical roles of SWI/SNF in animal development and tumorigenesis, how signaling pathways recruit SWI/SNF complexes to their target genes is unclear. Here, we demonstrate that target gene activation mediated by Beta-catenin, the essential transcriptional coactivator in the Wnt signal transduction pathway, requires ubiquitylation of the SWI/SNF component Brahma-related gene-1 (BRG1) by the E3 ubiquitin ligase Thyroid Hormone Receptor Interactor 12 (TRIP12). TRIP12 depletion in Drosophila, zebrafish, mouse organoids, and human cells attenuates Wnt signaling. Genetic epistasis experiments place TRIP12 activity downstream of the Beta-catenin destruction complex. TRIP12 interacts with and ubiquitylates BRG1, and BRG1 depletion blocks TRIP12-mediated Wnt pathway activation. TRIP12 promotes BRG1 binding to Beta-catenin in the presence of Wnt. Our findings support a model in which TRIP12 ubiquitylates BRG1 in the presence of Wnt and promotes its interaction with Beta-catenin, thereby bringing SWI/SNF to Wnt target genes. Our studies suggest a general mechanism by which cell signaling induces the interaction between BRG1 and pathway-specific transcription factors to recruit SWI/SNF complexes to their appropriate target genes.
Project description:We have shown that β-catenin overexpression induced blockage of monocyte-macrophage differentiation by inhibiting PU.1-targeted gene transcription including Egr2 expression in myeloid progenitor cells. Our results suggest that compromised PU.1-targeted gene transcription induced by β-catenin overexpression, at least partially, may mediate a pathogenic role of β-catenin in myeloid leukemia.
Project description:We have shown that β-catenin overexpression induced blockage of monocyte-macrophage differentiation by inhibiting PU.1-targeted gene transcription including Egr2 expression in myeloid progenitor cells. Our results suggest that compromised PU.1-targeted gene transcription induced by β-catenin overexpression, at least partially, may mediate a pathogenic role of β-catenin in myeloid leukemia. PUER cells were infected with retrovirus expressing beta-catenin-S33Y or control vector MIGR1. Five days after infection, the GFP positive cells were sorted by flow cytometry, and were treated with 4-OHT to induce the expression of PU.1. Total RNA was exacted from cell samples and purified by RNeasy Micro kit (Qiagen). cRNAs were generated and hybridized to the mouse whole genome 4Ã44K arrays according to manufacturerâs instructions (Agilent Technologies).
Project description:Wnt/β-catenin signaling is essential for intestinal stem cell homeostasis and aberrant activation of this signaling leads to tumorigenesis. Here we report a function of YTHDF1, an mRNA m6A reader, in mediating β-catenin hyperactivation. Wnt signaling promotes YTHDF1 expression at the translational level. YTHDF1 is dispensable for normal intestinal development in mice while essential for intestinal regeneration. Ythdf1 knockout reduces the stemness of intestinal stem cells, which blocks Wnt-driven tumorigenesis. Genome-wide analysis identifies a subset of Wnt signaling components regulated by YTHDF1 in an m6A-dependent manner. Moreover, we demonstrate that YTHDF1 promotes the translation of TCF7L2/TCF4 to augment β-catenin activation. Targeting YTHDF1 in the established tumors leads to tumor shrinkage and prolonged survival. Together, our studies uncover YTHDF1 as an integral regulator of Wnt signaling at the translational level during intestinal tumorigenesis, which might serve as a promising target for colorectal cancer therapy.
Project description:During mammalian kidney development, mesenchymal nephron progenitors (cap mesenchyme) differentiate into the epithelial cells that go on to form the nephron. Although differentiation of nephron progenitors is triggered by activation of Wnt/b-catenin signaling, constitutive activation of Wnt/b-catenin signaling blocks epithelialization of nephron progenitors. Full epithelialization of nephron progenitors requires transient activation of Wnt/b-catenin signaling. We performed transcriptional profiling of nephron progenitors responding to constitutive or transient activation of Wnt/b-catenin signaling. Nephron progenitors were FACS-isolated from BAC transgenic Six2GFPcre-positive embryonic kidneys at E16.5. Cells were aggregated by centrifugation at 850g for 5min and incubated in 10%FBS/DMEM containing either 4uM BIO or the equal volume of DMSO for 24hrs or 48hrs.
Project description:During mammalian kidney development, mesenchymal nephron progenitors (cap mesenchyme) differentiate into the epithelial cells that go on to form the nephron. Although differentiation of nephron progenitors is triggered by activation of Wnt/b-catenin signaling, constitutive activation of Wnt/b-catenin signaling blocks epithelialization of nephron progenitors. Full epithelialization of nephron progenitors requires transient activation of Wnt/b-catenin signaling. We performed transcriptional profiling of nephron progenitors responding to constitutive or transient activation of Wnt/b-catenin signaling.
Project description:Canonical Wnt and Nodal signaling are both required for induction of the primitive streak (PS), which guides organization of the early embryo. The Wnt effector β-catenin is thought to function in these early lineage specification decisions via transcriptional activation of Nodal signaling. Here, we demonstrate a broader role for β-catenin in PS formation by analyzing its genome-wide binding in a human embryonic stem cell model of PS induction. β-catenin occupies regulatory regions in numerous PS and neural crest genes, and direct interactions between β-catenin and the Nodal effectors SMAD2/3 are required at these regions for PS gene activation. Furthermore, OCT4 binding in proximity to these sites is likewise required for PS induction, suggesting a collaborative interaction between β-catenin and OCT4. Induction of neural crest genes by β-catenin is repressed by SMAD2/3, ensuring proper lineage specification. This study provides mechanistic insight into how Wnt signaling controls early cell lineage decisions. Examination of β-catenin binding in hESC incubated in media control (RPMI), media containing CHIR or CHIR+SB for 6h and analyzed by ChIP-sequencing
Project description:Canonical Wnt/B-catenin signaling is frequently dysregulated in myeloid leukemias and is implicated in leukemogenesis. Nuclear-localized β-catenin is indicative of active Wnt signaling and is frequently observed in acute myeloid leukemia (AML) patients; however, some patients exhibit little or no β-catenin nuclear-localization even where cytosolic B-catenin is abundant. Differential propensity for nuclear-localized β-catenin is also observed in cell lines. To investigate the factors mediating the nuclear-localization of B-catenin we carried out a nuclear/cytoplasmic proteomic analysis of the B-catenin interactome in myeloid leukemia cells. From this we identified hundreds of putative novel B-catenin-interactors. Comparison of interacting factors between Wnt-responsive cells (high nuclear B-catenin, K562/HEL) versus Wnt-unresponsive cells (low nuclear B-catenin, ML1) suggested the established interactor, LEF1, is a key factor mediating the nuclear-localization of B-catenin in myeloid leukemia. The relative levels of nuclear LEF1 and B-catenin were tightly correlated in both cell lines and in primary AML blasts. Furthermore, LEF1 knockdown inhibited B-catenin nuclear-localization and transcriptional activation in Wnt-responsive cells. Conversely, LEF1 overexpression was able to promote both nuclear-localization and B-catenin-dependent transcriptional responses in previously Wnt-unresponsive cells. This study is the first to present a B-catenin interactome in hematopoietic cells and reveals LEF1 as a critical regulator of canonical Wnt signaling in myeloid leukemia.
Project description:hLESC ex vivo cultures treated with GSK-3 inhibitor LY2090314 (small molecule) to activate Wnt/β-catenin signaling and further examine the impact of canonical Wnt/β-catenin signaling activation on hLESCs. We used microarray to explore the changes in gene expression in GSK-3 inhibitor LY2090314 treated and untreated ex vivo cultures of hLESCs to examine gene expression changes upon Wnt/β-catenin signaling activation in hLESCs.
Project description:Strong activation of the oncogenic Wnt/beta-catenin pathway is a main mechanism of resistance to FOXO3a-induced apoptosis promoted by PI3K and AKT inhibitors in colorectal cancer (CRC). Reducing Wnt/beta-catenin activity would sensitize colorectal tumors to these inhibitors. However, no Wnt/beta-catenin signaling inhibitor has proven clinical potential yet. Recently, inhibitors that block tankyrases were shown to reduce colon cancer cell proliferation by decreasing nuclear beta-catenin. We aim to identify determinants of response to these novel Wnt-inhibitors. Therefore, we treated in vivo three different patient-derived xenograft models (PDX; P2, P5 and P30) growing subcutaneously in NOD SCID mice with the novel tankyrase inhibitor NVP-TNKS656.