Foxh1/nodal defines context-specific direct maternal Wnt/Beta-catenin target gene regulation in early development
ABSTRACT: This study aimed to further understand context-specific direct Wnt target gene expression through the use of beta-catenin and FoxH1 ChIP Sequencing data at various developmental stages representing both maternal and zygotic Wnt signalling. Results were further supported through the use of RNA sequencing data from beta-catenin, FoxH1 and nodal gene knock down assays.
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:Deregulation of canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 (beta-catenin gene) are highly frequent in colon cancer and cause aberrant stabilization of b-catenin, which activates the transcription of Wnt target genes by binding to chromatin via the TCF/LEF transcription factors. Here we report an integrative analysis of genome-wide chromatin occupancy of b-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) and gene expression profiling by microarray analysis upon RNAi-mediated knockdown of beta-catenin in colon cancer cells (GSE53656). Immunoprecipitated samples from human colon cancer SW480 cells with antibodies against beta-catenin and control IgG respectively were used for ChIP-seq experiments.
Project description:Approximately 60-70% of patients with 22q11.2 deletion syndrome (22q11.2DS; velo-cardio-facial syndrome/DiGeorge syndrome) have cardiac outflow tract anomalies including persistent truncus arteriosus (PTA) as the most severe defect. Among the genes in the 22q11.2 region, TBX1, encoding a T-box transcription factor is a major candidate for cardiovascular malformations and its inactivation in mice results in a PTA. To identify novel signaling mechanisms that function downstream, we found that Tbx1 restricts canonical Wnt signaling in the pharyngeal apparatus. To test for tissue specificity within the pharyngeal apparatus, we inactivated Tbx1 in the anterior portion of the secondary heart field (AHF) mesoderm using the Mef2c-AHF-Cre allele and observed a full penetrant PTA (n = 30). Tbx1 promotes progenitor cells but restricts differentiation whereas Wnt signaling, in the AHF, promotes cardiomyocyte differentiation. To determine whether Tbx1 and canonical Wnt signaling act in opposing pathways, both alleles of Tbx1 and one β-catenin allele were inactivated in the AHF and 85% of them (n = 35) showed partial or complete rescue. The antagonistic function of the two pathways was further confirmed by gene expression profiling, indicating that these two pathways provide a key balance in the AHF to prevent premature differentiation of progenitor cells prior to reaching the cardiac outflow tract. We inactivatedTbx1 and beta-catenin allele to identify function of Tbx1 and beta-catenin in the anterior portion of the secondary heart field (AHF) mesoderm. We also inactivated both alleles of Tbx1 and one β-catenin alleles (rescue design) to determine whether Tbx1 and canonical Wnt signaling act in opposing pathways
Project description:The Wnt pathway is a key regulator of embryonic development, cell growth, differentiation, polarity formation, neural development, carcinogenesis, and stem cell self-renewal, and deregulation of the Wnt signalling is associated with many human disease. The central player in the Wnt pathway is β-catenin, A recent study has shown that β-catenin/Tcf/Lef signaling pathway is an essential growth-regulatory pathway in cardiomyocytes. We used DNA microarrays to detail the global trends in gene expression underlying β-catenin-overexpressed cardiomyocytes and identified distinct classes of up- or down-regulated genes during this process. Our findings suggest that β-catenin plays a critical role in regulating cardiac dysfunction at transcriptional level and may provide novel insight into how β-catenin modulates heart diseases. Cardiomyocytes were infected with GFP control or β-catenin adenoviruses for RNA extraction and hybridization on Affymetrix microarrays. We sought to define the effects of β-catenin on the global programme of gene expression in primary cardiomyocytes. To that end, neonatal rat cardiomyocytes were infected with GFP control (G) or β-catenin adenovirus (B) for 24 hours.
Project description:During canonical Wnt signalling the activity of nuclear beta-catenin is largely mediated by the TCF/LEF family of transcription factors. To challenge this view we used the CRISPR/Cas9 genome editing approach to generate HEK 293T cell clones simultaneously carrying loss-of-function alleles of all four TCF/LEF genes. Exploiting unbiased whole transcriptome sequencing studies, we found that a subset of beta-catenin transcriptional targets did not require TCF/LEF factors for their regulation. Consistent with this finding, we observed in a genome-wide analysis that beta-catenin occupied specific genomic regions in the absence of TCF/LEF. Finally, we revealed the existence of a transcriptional activity of beta-catenin that specifically appears when TCF/LEF factors are absent, and refer to this as beta-catenin-GHOST response. Collectively, this study uncovers a previously neglected modus operandi of beta-catenin that bypasses the TCF/LEF transcription factors.
Project description:Here we show that β-catenin mediates pro-resilient and anxiolytic effects in mice in the nucleus accumbens (NAc), a key brain reward region, an effect that is mediated by β-catenin signaling in D2-type medium spiny neurons (MSNs) specifically. Conversely, blocking β-catenin function in NAc promotes susceptibility to chronic stress, and we show evidence of robust suppression of β-catenin transcriptional activity in the NAc both of depressed humans examined postmortem as well as of mice that display a susceptible phenotype after chronic stress, with a converse upregulation in mice that are stress resilient. Using ChIP-seq, we demonstrate a global, genome-wide enrichment of β-catenin in the NAc of resilient mice, and specifically identify Dicer1—important in small RNA (e.g., microRNA [miRNA]) biogenesis—as a critical β-catenin target gene involved in mediating a resilient phenotype. Small RNA-seq after excising β-catenin from the NAc in the context of chronic stress reveals dynamic β-catenin-dependent miRNA regulation associated with resilience. Control: 2 samples, Resilient: 2 samples, Susceptible: 2 samples; DNA input: 1 sample.
Project description:Canonical Wnt/β-catenin signalling is an essential regulator of various cellular functions throughout development and adulthood. Aberrant Wnt/β-catenin signalling also contributes to various pathologies including cancer, necessitating an understanding of cell context dependent mechanisms regulating this pathway. Since protein-protein interactions underpin β-catenin function and localization, we sought to identify novel β-catenin interacting partners by affinity purification coupled with tandem mass spectrometry in vascular smooth muscle cells (VSMCs), where β-catenin is involved in both physiological and pathological control of cell proliferation. Here, we report novel components of the VSMC β-catenin interactome.
Project description:Microarray-based gene expression data were generated from RNA from Ls174T colorectal carcinoma cell lines in which Wnt-dependent transcriptional activity can be abrogated by inducible overexpression of a dominant-negative form of Tcf4 or siRNA against β-catenin. shRNA against β-catenin, or a dominant-negative Tcf4 transgene, were induced in Ls174T cells for 72 or 24 hours, respectively. Uninduced cells were used as a control. Three replicates per condition.
Project description:Foxp3 is crucial for both the development and function of regulatory T cells (Treg),however the post-translational mechanisms regulating Foxp3 transcriptional output remain poorly defined. Here, we demonstrate that TCF1 and Foxp3 interact in the nucleus of Treg, and that active Wnt-signaling disrupts Foxp3 transcriptional activity. Utilizing a global ChIP-seq comparison we demonstrate considerable overlap between Foxp3 and Wnt target genes in Treg. Activation of Wnt signaling significantly reduces Treg-mediated suppression both in vitro and in vivo, while disruption of Wnt signaling in Treg enhances their suppressive capacity. Activation of effector T cells increases Wnt3a production, and Wnt3a levels were found to be greatly increased in mononuclear cells isolated from synovial fluid versus peripheral blood of arthritis patients. We propose a model in which Wnt produced by activated mononuclear cells under inflammatory conditions represses Treg function allowing a productive immune response, but if uncontrolled could lead to the development of autoimmunity. Beta catenin ChIP-seq in Treg
Project description:Beta-catenin is an essential mediator of canonical Wnt signaling and a central component of the cadherin-catenin epithelial adhesion complex. Dysregulation of beta-catenin expression has been described in pancreatic neoplasia. Newly published studies have suggested that beta-catenin is critical for normal pancreatic development although these reports reached somewhat different conclusions. In addition, the molecular mechanisms by which loss of beta-catenin affects pancreas development are not well understood. The goals of this study then were; 1] to further investigate the role of beta-catenin in pancreatic development using a conditional knockout approach and 2] to identify possible mechanisms by which loss of beta-catenin disrupts pancreatic development. A Pdx1-cre mouse line was used to delete a floxed beta-catenin allele specifically in the developing pancreas, and embryonic pancreata were studied by immunohistochemistry and microarray analysis. Experiment Overall Design: Parameter: embryonic pancreas from wild type and Pdx1Cre/+; beta-cateninflox/flox Experiment Overall Design: Sample type: RNA Experiment Overall Design: Source name: Embryonic day 14.6 and 16.5 pancreas Experiment Overall Design: Organism: Mus Musculus Experiment Overall Design: Strain: Derived from an intercross of Pdx1Cre/+ ; beta-cateninflox/+ mice. Experiment Overall Design: Extracted molecule:Total RNA Experiment Overall Design: In the study, we hybridized RNA from Embryonic day 14.6 and 16.5 pancreas of wild type (WT) control and Pdx1Cre/+; beta-cateninflox/flox beta-catenin null in the pancreas) embryonic pancreas to Affymetrix MOE430 2.0 GeneChip® arrays containing 45,101 well characterized mouse genes/ESTs.