ABSTRACT: Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. β-catenin is widely thought to be a major oncogene in HCC based on the frequency of mutations associated with aberrant Wnt signaling in HCC patients. Challenging this model, our data reveal that β-catenin nuclear accumulation is restricted to the late stage of the disease. Until then, β-catenin is primarily located at the plasma membrane in complex with multiple cadherin family members where it drives tumor cell survival by enhancing the signaling of growth factor receptors such as EGFR. Therefore, our study reveals the evolving nature of β-catenin in HCC to establish it as a compound tumor promoter during the progression of the disease.
Project description:Colorectal cancer (CRC) is the third most commonly diagnosed cancer, which despite recent advances in treatment, remains incurable due to molecular heterogeneity of tumor cells. The B-cell lymphoma 9 (BCL9) oncogene functions as a transcriptional co-activator of the Wnt/β-catenin pathway, which plays critical roles in CRC pathogenesis. Here we have identified a β-catenin-independent function of BCL9 in a poor-prognosis subtype of CRC tumors characterized by expression of stromal and neural associated genes. In response to spontaneous calcium transients or cellular stress, BCL9 is recruited adjacent to the interchromosomal regions, where it stabilizes the mRNA of calcium signaling and neural associated genes by interacting with paraspeckle proteins. BCL9 subsequently promotes tumor progression and remodeling of the tumor microenvironment (TME) by sustaining the calcium transients and neurotransmitter-dependent communication among CRC cells. These data provide additional insights into the role of BCL9 in tumor pathogenesis and point towards additional avenues for therapeutic intervention.
Project description:β-catenin activity of dermal cells is crucial for hair follicle neogenesis and strongly suggest that transcriptional target genes of β-catenin pathway are essential for maintaining trichogenicity of dermal cells. We used microarrays to identify genes targeted by the β-catenin pathway that are essential for maintaining the trichogenicity of dermal cells. Freshly isolated dermal cells from the dorsal skins of C57BL/6 neonates (P0) were cultured for 24 hours and transfected with either control siRNA or β-catenin specific siRNAs (β-catenin siRNA) at a final concentration of 10 nM for 48 hours followed by RNA extraction and hybridization on Affymetrix microarrays.
Project description:In nucleated cells, β-catenin, the key downstream effector of this pathway, is a dual function protein, regulating the coordination of gene transcription and cell–cell adhesion. The specific role of β-catenin in the anucleate platelet however remains elusive. Here, we performed a label-free quantitative proteomic analysis of β-catenin immunoprecipitates from human platelets identifying 9 co-immunoprecipitating proteins. GO biological pathway analysis revealed a significant enrichment of specific functional terms including 'cell adhesion', 'cell junction organization' and ‘adherens junction organization'. Our bioinformatics data suggests that human platelet β-catenin may be involved in facilitating cell adhesion and cell junctions. We found three proteins co-immunoprecipitating with β-catenin under both resting and activated conditions, four proteins under resting condition only and two proteins under activated condition only.
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: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: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:Basal cell carcinoma initiating cells undergo profound and rapid reprogramming into embryonic hair follicle progenitor like fate upon SmoM2 expression. Activation of Wnt/β-catenin signaling pathways is required in a cell autonomous manner for the reprogramming of adult IFE progenitors into EHFP-like fate as well as for tumor initiation. We used MA to define the molecular changes that occur in basal cell carcinoma initiating cells form the first oncogenic hit to the development of invasive tumor and further on to investigate the role of Wnt/β-catenin signaling activation in molecular changes occurring early during BCC development. Basal interfollicular cells expressing SmoM2 were FACS isolated at different stages of tumor development and in β-catenin LOF condition for RNA extraction and hybridization on Affymetrix microarrays. By comparing the transcriptional profile of SmoM2 expressing cells with FACS-isolated cells from littermate control mice, we determined a list of genes differentially regulated by SmoM2 expression as specific SmoM2 signature.
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: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:To validate the suitability of two commonly used colorectal cancer cell lines, DLD1 and SW480, as model systems to study colorectal carcinogenesis, we treated these cell lines with β-catenin siRNA and identified β-catenin target genes using DNA microarrays. The list of identified target genes was compared to previously published β-catenin target genes found in the PubMed and the GEO databases. Based on the large number of β-catenin target genes found to be similarly regulated in DLD1, SW480 and LS174T as well as the large overlap with confirmed β-catenin target genes, we conclude that DLD1 and SW480 colon carcinoma cell lines are suitable model systems to study β-catenin regulated genes and signaling pathways 12 arrays (2 cell lines, 2 treatments, 3 biological replicates)