Project description:Gene experssion was evaluated in the lungs of mice in which beta-catenin was stabilized or knocked out in the SCGB1A1 lineage. Gene expression was assayed on post-natal day 21
Project description:To elucidate the comprehensive changes regulated by β-catenin/TCF-dependent signaling in liver cancer cells, we explored a global gene expression of HepG2 cells after knockdown of β-catenin.
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: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:To identify evolutionarily conserved Beta-catenin protein interactions, Beta-catenin mRNA from various metazoans was injected into Xenopus embryos and immunopurified at gastrula stage. Beta-catenin complexes were then separated on an SDS-PAGE gel and subjected mass spectrometric analysis
Project description:Notch activation is instrumental in the development of most T-cell acute lymphoblastic leukemia (T-ALL) cases, yet Notch mutations alone are not sufficient to recapitulate the full human disease in animal models. Using multiple in vivo and in vitro T-ALL models we here demonstrate that β-Catenin is essential for Notch-driven T-cell leukemic initiation. Transcriptome analyses of leukemic initiating cells revealed a switch in β-Catenin activity that was Notch-context dependent. Moreover, ChIP-seq coupled with RNA-Seq in human Notch-active T-ALL showed that leukemic β-Catenin was independent of canonical LEF/TCF partners, and instead depended on direct association with Notch or ZBTB33/Kaiso for gene activation. The functional relevance of this mechanism is exemplified by the MYC 3´enhancer that requires β-Catenin and Notch1 recruitment to induce MYC expression. Finally, we demonstrate that pharmacological inhibition of β-Catenin with PKF115-584 prevented and partially reverted leukemogenesis induced by active Notch1. These microarray data show the transcriptional activities of N1IC and β-Catenin in wild-type or leukemic initiating cell (LIC) contexts in E14.5 FL LSK cells.
Project description:The regulation of gonadotropin synthesis by GnRH (Gonadotropin-releasing hormone) plays an essential role in the neuroendocrine control of reproduction. The known signaling mechanisms involved in gonadotropin synthesis have been expanding. For example, involvement of β-catenin in LHβ induction by GnRH has been discovered. We examined the role of β-catenin in FSHβ gene expression in LβT2 gonadotrope cells. GnRH caused a sustained increase in nuclear β-catenin levels, which was significantly reduced by JNK inhibition. siRNA-mediated knockdown of β-catenin mRNA demonstrated that induction of FSHβ mRNA by GnRH depended on β-catenin and that regulation of FSHβ by β-catenin occurred independently of the JNK-c-jun pathway. β-catenin depletion had no impact on FSHβ mRNA stability. In LβT2 cells transfected with FSHβ promoter luciferase fusion constructs, GnRH responsiveness was conferred by the proximal promoter (-944/-1), and was markedly decreased by β-catenin knockdown. However, none of the TCF/LEF binding sites in that region were required for promoter activation by GnRH. Chromatin immunoprecipitation further corroborated the absence of direct interaction between β-catenin and the 1.8 kb FSHβ promoter. To elucidate the mechanism for the β-catenin effect, we analyzed ~1 billion reads of next generation RNA sequencing β-catenin knockdown assays and selected the nuclear cofactor Brms1L as one candidate for further study. Subsequent experiments confirmed that Brms1L mRNA expression was decreased by β-catenin knockdown as well as by JNK inhibition. Furthermore, knockdown of Brms1L significantly attenuated GnRH-induced FSHβ expression. Thus, our findings indicate that the expression of Brms1L depends on β-catenin activity and contributes to FSHβ induction by GnRH.
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.