Project description:Wnt/M-NM-2-catenin signaling is involved in various aspects of skeletal muscle development and regeneration. In addition, Wnt3a and M-NM-2-catenin are required for muscle-specific gene transcription in embryonic carcinoma cells and satellite-cell proliferation during adult skeletal muscle regeneration. Downstream targets of canonical Wnt signaling are cyclin D1 and c-myc. However, both target genes are suppressed during differentiation of mouse myoblast cells, C2C12. Underlying molecular mechanisms of M-NM-2-catenin signaling during myogenic differentiation remain unknown. Using C2C12 cells, we examined intracellular signaling and gene transcription during myoblast proliferation and differentiation. We confirmed that several Wnt signaling components, including Wnt9a, Sfrp2 and porcupine, were consistently upregulated in differentiating C2C12 cells. Troponin T-positive myotubes were decreased by Wnt3a overexpression, but not Wnt4. TOP/FOP reporter assays revealed that co-expression with Wnt4 reduced Wnt3a-induced luciferase activity, suggesting that Wnt4 signaling counteracted Wnt3a signaling in myoblasts. FH535, a small-molecule inhibitor of M-NM-2-catenin/Tcf complex formation, reduced basal M-NM-2-catenin in cytoplasm and decreased myoblast proliferation. K252a, a protein kinase inhibitor, increased membrane-bound M-NM-2-catenin and enhanced myoblast fusion. Treatments with K252a or Wnt4 resulted in increased cytoplasmic vesicles containing phosphorylated M-NM-2-catenin (Tyr654) during myogenic differentiation. These results suggest that various Wnt ligands control subcellular M-NM-2-catenin localization, which regulate myoblast proliferation and myotube formation. Wnt signaling via M-NM-2-catenin likely acts as a molecular switch that regulates the transition from cell proliferation to myogenic differentiation. Control cells (day 0) prior to differentiation induction with n=4; differentiated for two days with n=3; differentiated for four days with n=3.
Project description:Wnt/β-catenin signaling is involved in various aspects of skeletal muscle development and regeneration. In addition, Wnt3a and β-catenin are required for muscle-specific gene transcription in embryonic carcinoma cells and satellite-cell proliferation during adult skeletal muscle regeneration. Downstream targets of canonical Wnt signaling are cyclin D1 and c-myc. However, both target genes are suppressed during differentiation of mouse myoblast cells, C2C12. Underlying molecular mechanisms of β-catenin signaling during myogenic differentiation remain unknown. Using C2C12 cells, we examined intracellular signaling and gene transcription during myoblast proliferation and differentiation. We confirmed that several Wnt signaling components, including Wnt9a, Sfrp2 and porcupine, were consistently upregulated in differentiating C2C12 cells. Troponin T-positive myotubes were decreased by Wnt3a overexpression, but not Wnt4. TOP/FOP reporter assays revealed that co-expression with Wnt4 reduced Wnt3a-induced luciferase activity, suggesting that Wnt4 signaling counteracted Wnt3a signaling in myoblasts. FH535, a small-molecule inhibitor of β-catenin/Tcf complex formation, reduced basal β-catenin in cytoplasm and decreased myoblast proliferation. K252a, a protein kinase inhibitor, increased membrane-bound β-catenin and enhanced myoblast fusion. Treatments with K252a or Wnt4 resulted in increased cytoplasmic vesicles containing phosphorylated β-catenin (Tyr654) during myogenic differentiation. These results suggest that various Wnt ligands control subcellular β-catenin localization, which regulate myoblast proliferation and myotube formation. Wnt signaling via β-catenin likely acts as a molecular switch that regulates the transition from cell proliferation to myogenic differentiation.
Project description:Wnt/beta-catenin signaling is involved in various aspects of skeletal muscle development and regeneration. Using C2C12 cells, we examined intracellular signaling and gene transcription during myoblast proliferation and differentiation. The results of the present studies suggest that Wnt signaling is interacting with TGF-beta superfamily signaling through Smad activation. Single analysis for each condition (proliferating C2C12 cells, differentiating C2C12 cells, proliferating Wnt4-overexpressing C2C12 subline cells).
Project description:Wnt/beta-catenin signaling is involved in various aspects of skeletal muscle development and regeneration. Using C2C12 cells, we examined intracellular signaling and gene transcription during myoblast proliferation and differentiation. The results of the present studies suggest that Wnt signaling is interacting with TGF-beta superfamily signaling through Smad activation.
Project description:The histone 3 lysine 9 (H3K9)-specific methyltransferase (KMT) Setdb1 is essential for both stem cell pluripotency and terminal differentiation of different cell types. To shed light on Setdb1 role(s) in these mutually exclusive processes, we used mouse skeletal myoblasts as a model of terminal differentiation. Ex vivo studies on isolated single myofibres showed that Setdb1 is required for muscle adult stem cells expansion following activation and in vitro studies on skeletal myoblasts confirmed that Setdb1 suppresses terminal myoblast differentiation. We used genome-wide analyses to identify Setdb1 direct target genes in myoblasts and observed a release of Setdb1 from the promoter of selected target genes upon myoblast terminal differentiation, concomitant to a nuclear export of Setdb1 to the cytoplasm. We demonstrated that both genomic release and cytoplasmic Setdb1 relocalisation during differentiation were dependent on canonical Wnt signalling. Taken together, our findings uncover a functional link between Setdb1 and canonical Wnt signalling in skeletal muscle cells, which affects the expression of a subset of Setdb1 target genes. We revealed Wnt-dependent subcellular relocalisation of Setdb1 as a novel mechanism regulating Setdb1 functions. ChIP-seq of Setdb1 and H3K9me3 in Myoblast cells (C2C12)