Intermolecular 3′UTR-3′UTR interactions drive Wnt gene activation through heteromeric protein assembly
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE329836 | GEO | 2026/05/05
REPOSITORIES: GEO
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Project description:The Wnt signalling pathway is commonly mutated or dysregulated in colorectal cancer, including approximately 93% of solid tumour samples from The Cancer Genome Atlas. Such dysregulation commonly leads to overactivation of CTNNB1, a transcription factor central to Wnt signalling. We have previously observed an increase in splicing of the 3'UTR of CTNNB1 in colon cancer samples compared to healthy samples. Additionally, we have observed isoform-specific regulation of CTNNB1 3'UTR spliced and retained isoforms in response culturing HCT116 cells with increasing concentrations of Wnt activator CHIR99021, and the opposite upon incubation with Wnt inhibitor IWR-1. By treating HCT116 cells with a high concentration of Wnt activator CHIR99021 and performing RNA sequencing, we assessed the global impact of Wnt signalling on expression of transcripts with spliced 3'UTRs. Interestingly, we observe an enrichment of alternative splicing events relating to components of the canonical Wnt signalling pathway itself, highlighting potential autoregulatory functions.
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Project description:Protein synthesis is a universal process mainly regulated at the initiation stage to permit a rapid and reversible control of cellular and environmental changes. Several stress conditions such as hypoxia, activate the translational reprogramming of mRNAs encoding proteins essential for stress recovery and cell survival. Increasing evidence of unconventional translation initiation mechanisms lead by 5’UTR motifs, shows the cells potential to adapt their translation machinery in response to different stimuli. β-catenin is an oncogenic protein playing an essential role in Wnt signal transduction. Dysregulation of this pathway causes aberrant nuclear β-catenin accumulation, which consequently modulates the expression of genes related to cancer development and metastasis. To date, the mechanism of its translation maintenance in stressed cells remains elusive. To understand how β-catenin mRNA escapes global translational blockade in hypoxic cancer cells, we determined the 5’UTR secondary structure and searched for translation regulatory elements in living cells. We found that a three-way junction (TWJ) within its 5’UTR is involved in the translation efficiency (TE) of β-catenin and its enhancement under hypoxia. We showed that the TWJ single-stranded polypurine region becomes, in the absence of eIF4E, an alternative anchoring site for eIF4B, eIF4A and eIF4G. Importantly, the TWJ makes the β-catenin mRNA translation eIF4A-dependent being sensible to silvestrol, a selective eIF4A inhibitor and promising anticancer agent. Our study unravels the 5’UTR-driven translation regulation mechanism of β-catenin mRNA and set the basis to explore its inhibition in the frame of cancer progression.
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Project description:Medulloblastoma is the most frequent malignant pediatric brain tumor. Considerable efforts are dedicated to identify markers that help to refine treatment strategies. The activation of the Wnt/beta-catenin pathway occurs in 10-15% of medulloblastomas and has been recently described as a marker for favorable patient outcome. We report a series of 72 pediatric medulloblastomas evaluated for beta-catenin immunostaining, CTNNB1 mutations, and studied by comparative genomic hybridization. Gene expression profiles were also available in a subset of 40 cases. Immunostaining of beta-catenin showed extensive nuclear staining (>50% of the tumor cells) in 6 cases and focal nuclear staining (<10% of cells) in 3 cases. The other cases exhibited either a signal strictly limited to the cytoplasm (58 cases) or were negative (5 cases). CTNNB1 mutations were detected in all beta-catenin extensively nucleopositive cases. The expression profiles of these cases documented a strong activation of the Wnt/beta-catenin pathway. Remarkably, 5 out of these 6 tumors showed a complete loss of chromosome 6. In contrast, cases with focal nuclear beta-catenin staining, as well as tumors with negative or cytoplasmic staining, never demonstrated CTNNB1 mutation, Wnt/beta-catenin pathway activation or chromosome 6 loss. Patients with extensive nuclear staining were significantly older at diagnosis and were in continuous complete remission after a mean follow-up of 75.7 months (range 27.5-121.2) from diagnosis. All three patients with a focal nuclear staining of beta-catenin died within 36 months from diagnosis. Altogether, these data confirm and extend previous observations that CTNNB1-mutated tumors represent a distinct molecular subgroup of medulloblastomas with favorable outcome, indicating that therapy de-escalation should be considered. Yet, international consensus on the definition criteria of this distinct medulloblastoma subgroup should be achieved. A series of 72 pediatric medulloblastoma tumors has been studied at the genomic level (array-CGH), screened for CTNNB1 mutations and beta-catenin expression (immunohistochemistry). A subset of 40 tumor samples has been analyzed at the RNA expression level (Affymetrix HG U133 Plus 2.0). Correlations between the genomic data, the expression data, the mutational screening, the pathological classification and clinical data is presented in the study. note: aCGH data not submitted to GEO
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Project description:Endothelial-derived Wnt/Ctnnb1-signaling is an important angiocrine regulator. Ctnnb1 gain-of-function (GOF) in sinusoidal endothelial cells was generated via Stab2-iCreF3tg/wt Ctnnb1(Ex3)fl/wt mice to analyze the effects of endothelial β-catenin signaling on bone marrow function. We used microarrays to detail the global programme of gene expression in bone marrow EMCN+ cells with β-catenin (Ctnnb1) gain-of-function compared to Wildtype.
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Project description:Gain-of-function mutations in exon 3 of beta-catenin (CTNNB1) are specific for Wilms' tumors that have lost WT1, but 50% of WT1-mutant cases lack such "hot spot" mutations. To ask whether stabilization of beta-catenin might be essential after WT1 loss, and to identify downstream target genes, we compared expression profiles in WT1-mutant versus WT1 wild-type Wilms' tumors. Supervised and nonsupervised hierarchical clustering of the expression data separated these two classes of Wilms' tumor. The WT1-mutant tumors overexpressed genes encoding myogenic and other transcription factors (MOX2, LBX1, SIM2), signaling molecules (TGFB2, FST, BMP2A), extracellular Wnt inhibitors (WIF1, SFRP4), and known beta-catenin/TCF targets (FST, CSPG2, CMYC). Beta-Catenin/TCF target genes were overexpressed in the WT1-mutant tumors even in the absence of CTNNB1 exon 3 mutations, and complete sequencing revealed gain-of-function mutations elsewhere in the CTNNB1 gene in some of these tumors, increasing the overall mutation frequency to 75%. Lastly, we identified and validated a novel direct beta-catenin target gene, GAD1, among the WT1-mutant signature genes. These data highlight two molecular classes of Wilms' tumor, and indicate strong selection for stabilization of beta-catenin in the WT1-mutant class. Beta-Catenin stabilization can initiate tumorigenesis in other systems, and this mechanism is likely critical in tumor formation after loss of WT1. Experiment Overall Design: Identification of WNT/Beta-Catenin or WT1 target genes. 39 individual samples.
2008-06-14 | E-GEOD-6120 | biostudies-arrayexpress
Project description:Up to 41% of hepatocellular carcinomas (HCCs) result from activating mutations in the CTNNB1 gene encoding β-catenin. β-catenin has dual cellular functions as a component of the Wnt signaling pathway and adherens junctions. HCC-associated CTNNB1 mutations stabilize the β-catenin protein, leading to nuclear and/or cytoplasmic localization of β-catenin and downstream activation of Wnt target genes. In patient HCC samples, β-catenin nuclear and cytoplasmic localization are typically patchy, even among HCC with highly active CTNNB1 mutations. The functional and clinical relevance of this heterogeneity in β-catenin activation are not well understood. To define mechanisms of β-catenin-driven HCC initiation, we generated a Cre-lox system that enabled switching on activated β-catenin in 1) a small number of hepatocytes in early development; or 2) the majority of hepatocytes in later development or adulthood. We discovered that switching on activated β-catenin in a subset of larval hepatocytes was sufficient to drive HCC initiation. To determine the role of Wnt/β-catenin signaling heterogeneity later in hepatocarcinogenesis, we performed RNA-seq analysis of zebrafish β-catenin-driven HCC. Ingenuity Pathway Analysis of differentially expressed genes in the Cre-lox HCC model revealed that “Cancer” and “Liver Tumor” categories were significantly altered, indicating transcriptional similarities with human HCC and other vertebrate HCC models. At the single-cell level, 2.9% to 15.2% of hepatocytes from zebrafish β-catenin-driven HCC expressed two or more of the Wnt target genes axin2, mtor, glula, myca, and wif1, indicating focal activation of Wnt signaling in established tumors. Thus, heterogeneous β-catenin activation drives HCC initiation and persists throughout hepatocarcinogenesis.
2019-09-27 | GSE137784 | GEO
Project description:Up to 41% of hepatocellular carcinomas (HCCs) result from activating mutations in the CTNNB1 gene encoding β-catenin. β-catenin has dual cellular functions as a component of the Wnt signaling pathway and adherens junctions. HCC-associated CTNNB1 mutations stabilize the β-catenin protein, leading to nuclear and/or cytoplasmic localization of β-catenin and downstream activation of Wnt target genes. In patient HCC samples, β-catenin nuclear and cytoplasmic localization are typically patchy, even among HCC with highly active CTNNB1 mutations. The functional and clinical relevance of this heterogeneity in β-catenin activation are not well understood. To define mechanisms of β-catenin-driven HCC initiation, we generated a Cre-lox system that enabled switching on activated β-catenin in 1) a small number of hepatocytes in early development; or 2) the majority of hepatocytes in later development or adulthood. We discovered that switching on activated β-catenin in a subset of larval hepatocytes was sufficient to drive HCC initiation. To determine the role of Wnt/β-catenin signaling heterogeneity later in hepatocarcinogenesis, we performed RNA-seq analysis of zebrafish β-catenin-driven HCC. Ingenuity Pathway Analysis of differentially expressed genes in the Cre-lox HCC model revealed that “Cancer” and “Liver Tumor” categories were significantly altered, indicating transcriptional similarities with human HCC and other vertebrate HCC models. At the single-cell level, 2.9% to 15.2% of hepatocytes from zebrafish β-catenin-driven HCC expressed two or more of the Wnt target genes axin2, mtor, glula, myca, and wif1, indicating focal activation of Wnt signaling in established tumors. Thus, heterogeneous β-catenin activation drives HCC initiation and persists throughout hepatocarcinogenesis.
2019-09-27 | GSE137787 | GEO
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2013-12-27 | E-GEOD-53656 | biostudies-arrayexpress
Project description:Deregulation of the canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 are frequent in colon cancer and cause aberrant stabilization of beta-catenin, which activates Wnt target genes by binding to chromatin via TCF/LEF transcription factors. In a comprehensive study, we conducted an integrative analysis of genome-wide chromatin occupancy of beta-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) along with gene expression profiling changes resulting from RNAi-mediated knockdown of beta-catenin in colon cancer cells. This experiment series represents the gene expression changes detected by microarray as a result of CTNNB1 perturbation.
2013-12-27 | GSE53656 | GEO
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.
2014-03-12 | E-GEOD-53927 | biostudies-arrayexpress