Project description:We report ChIP-Seq experiments to profile the genomic binding dynamics of ß-catenin, SOX17, SOX2 and TCF/LEF TFs in definitive endoderm and neuromesodermal progenitor cells and RNA-Seq/ATAC-Seq experiments for transcriptomic and chromatin profiling of these cell types.
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: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:Both TCF-1 and its coactivator β-catenin are known to be required for supporting normal double positive (DP) thymocyte survival through upregulating Bcl-xL. However, the downstream factors mediating this effect remained unknown. We used microarray to compare the global expression difference among WT, TCF-1-deficient, and β-catenin transgenic thymocytes to search for the genes that are down-regulated and up-regulated in TCF-1-deficient and β-catenin transgenic thymocytes, respectively. We focus on the genes that are significantly down-regulated and up-regulated in TCF-1-deficient and β-catenin transgenic thymocytes, respectively, to select for those genes that are potential target genes of β-catenin/TCF-1 pathway. And then those genes are subject to IPA pathway analysis searching for genes that are involved in thymocyte development and cell death.
Project description:We sought to identify the carcinogenic mechanisms involved in RKO cell line with no evidence of activated β-catenin/TCF regulated transcription, by comparison its gene expression profile to that of group of colorectal cancer cell lines selected to be mismatch repair deficient similar to RKO and having activate Wnt signaling.
Project description:Both TCF-1 and its coactivator β-catenin are known to be required for supporting normal double positive (DP) thymocyte survival through upregulating Bcl-xL. However, the downstream factors mediating this effect remained unknown. We used microarray to compare the global expression difference among WT, TCF-1-deficient, and β-catenin transgenic thymocytes to search for the genes that are down-regulated and up-regulated in TCF-1-deficient and β-catenin transgenic thymocytes, respectively.
Project description:The forkhead box transcription factor FOXQ1 is aberrantly induced in various cancers, and contributes to tumour growth and metastasis. It has been suggested that the oncogenic potential of FOXQ1 may be explained by its activation of the Wnt/β-catenin signalling pathway.However, the mode of action of FOXQ1 in the Wnt pathway remains to be resolved. Here we report that FOXQ1 is bimodal transcriptional activator of Wnt target gene expression in normal and cancer cells. Using co-immunoprecipitation, proximity proteomics, and reporter assays, we show that FOXQ1 engages the Wnt transcriptional complex to promote gene expressionvia TCF/LEF transcription factors.
Project description:Background & Aims. Sporadic colorectal cancers arise from mutations in APC, producing oncogenic β-catenin/TCF-dependent transcriptional reprogramming. The tumor suppressor axis regulated by the intestinal epithelial receptor, GUCY2C, is among the earliest pathways silenced in tumorigenesis. Retention of the receptor, but loss of its paracrine ligands, guanylin and uroguanylin, is an evolutionarily conserved feature of colorectal tumors, arising in the earliest dysplastic lesions. Here, we examined a mechanism of GUCY2C ligand transcriptional silencing by β-catenin/TCF signaling. Methods. We performed RNA-seq analysis of four unique conditional human colon cancer cell models of β-catenin/TCF signaling to map the core Wnt-transcriptional program. We then performed a comparative analysis of orthogonal approaches, including luciferase reporters, ChIP-seq, CRISPR Cas9 knockout, and CRISPR epigenome editing, which were cross-validated with human tissue ChIP-seq datasets, to identify functional gene enhancers mediating GUCY2C ligand loss. Results. RNA-seq analyses reveal the GUCY2C hormones as two of the most sensitive targets of β-catenin/TCF signaling, reflecting transcriptional repression. The GUCY2C hormones share an insulated genomic locus containing a novel locus control region upstream of the guanylin promoter that mediates the coordinated silencing of both genes. Targeting this region with CRISPR epigenome editing reconstituted GUCY2C ligand expression, overcoming gene inactivation by mutant β-catenin/TCF signaling. Conclusions. These studies reveal novel DNA elements regulating co-repression of GUCY2C ligand transcription by β-catenin/TCF signaling, reflecting a novel pathophysiological step in tumorigenesis. They offer unique genomic strategies that could re-establish hormone expression in the context of canonical oncogenic mutations to reconstitute the GUYC2C axis and oppose transformation.