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:Abstract Hippo pathway downstream effectors Yap and Taz play key roles in cell proliferation and regeneration, regulating gene expression especially via interaction with Tead transcription factors. To investigate their role in skeletal muscle stem cells, we analysed Taz in vivo and ex vivo in comparison to Yap. Taz was expressed in activated satellite cells. siRNA knockdown or constitutive expression of wildtype or constitutively active TAZ mutants showed that TAZ promoted proliferation, a function that was shared with YAP. However, at later stages of myogenesis, TAZ also enhanced myogenic differentiation of myoblasts, whereas YAP inhibits such differentiation. Functionally, while muscle growth was mildly affected in Taz (gene symbol Wwtr1-/-) knockout mice, there were no overt effect on regeneration. However, conditional knockout of Yap in satellite cells of Pax7Cre-ERT2/+ : Yapflox/flox : Rosa26Lacz mice produced a marked regeneration deficit. To identify potential mechanisms, microarray analysis showed many common Taz/Yap targets, but Taz also regulates some genes independently of Yap, including myogenic genes such as Pax7, Myf5 and Myod1. Proteomic analysis of Yap/Taz revealed many common binding partners, but Taz also interacts with proteins distinct from Yap, that are mainly involved in myogenesis and aspects of cytoskeleton organization. Neither TAZ nor YAP bind members of the Wnt destruction complex but both extensively changed expression of Wnt and Wnt-cross talking genes with known roles in myogenesis. Finally, TAZ operates through Tead4 to enhance myogenic differentiation. In summary, Taz and Yap have overlapping functions in promoting myoblast proliferation but Taz then switches to promote myogenic differentiation.
Project description:KSRP knock-down and BMP2 treatment produce a largely overlapping reshape of the transcriptome in C2C12 cells. microRNAs (miRNAs) are essential regulators of development, physiology, and evolution with miRNA biogenesis being strictly controlled at multiple levels. Regulatory proteins, such as KH-type splicing regulatory protein (KSRP), modulate rates and timing of the enzymatic reactions responsible for maturation of select miRNAs from their primary transcripts in response to specific stimuli. Induction of myogenic miRNAs (myomiRs) is essential for muscle differentiation with KSRP phosphorylation being required to convey myogenic signals to enhanced myomiR maturation. Here we show that either KSRP silencing or Bone Morphogenetic Protein (BMP)2-signaling activation in mesenchimal C2C12 cells prevented myogenic differentiation while induced osteoblastic differentiation as revealed by the reshaping of the whole transcriptome analyzed by RNA deep-sequencing. The most striking feature common to both BMP2 signaling activation and KSRP silencing was a blockade of myomiR maturation. Our results demonstrate that phosphorylated SMAD proteins, the transducers of BMP signaling, associate with KSRP and block its interaction with primary-myomiRs. This, in turn, abrogates KSRP-dependent myomiR maturation with the knock-down of SMAD4, 5, and 9 being able to rescue KSRP function. SMAD-induced blockade of KSRP-dependent myomiR maturation, in parallel to the well known SMAD function on gene transcription, inhibits C2C12 cell differentiation into myofibers and contributes to orient cells towards osteoblast lineage. We propose that remodeling of co-regulatory complexes affecting primary-miRNA processing is a mechanism well suited to guide cell fate determination in eukaryotes. Total RNA was prepared from 1. untreated mock-transfected C2C12 cells; 2. BMP2-treated mock-transfected C2C12 cells; 3. untreated shKSRP-transfected C2C12 cells and analyzed by RNA-seq
Project description:Controlled myogenic differentiation is integral to the development, maintenance and repair of skeletal muscle, necessitating precise regulation of myogenic progenitors and resident stem cells. The transformation of proliferative muscle progenitors into multinuclear syncytia involves intricate cellular processes driven by cytoskeletal reorganization. While actin and microtubles have been extensively studied, we illuminate the role of septins, an essential yet still often overlooked cytoskeletal component, in myoblast architecture. Notably, Septin9 emerges as a critical regulator of myoblast differentiation during the initial commitment phase. Knock-down of Septin9 in C2C12 cells and primary mouse myoblasts accelerates the transition from proliferation to committed progenitor transcriptional programs. Furthermore, we unveil significant reorganization and downregulation of Septin9 during myogenic differentiation. Collectively, we propose that filmamentous septin structures and their orchestrated reorganization in myoblasts are part of a temporal regulatory mechanism governing the differentiation of myogenic progenitors. This study sheds light on the dynamic interplay between cytoskeletal components underlying controlled myogenic differentiation.
Project description:Analysis of the transcriptome of zebrafish mononuclear myogenic cells (zMNCs) during myogenic differentiation. The main goal is to identify the similarities of zMNC myogenic differentiation with that of mammalian myoblast differentiation. Critical time points were used to identify a switch from the activity of cell proliferation genes to myogenic structural genes.
Project description:Analysis of the transcriptome of zebrafish mononuclear myogenic cells (zMNCs) during myogenic differentiation. The main goal is to identify the similarities of zMNC myogenic differentiation with that of mammalian myoblast differentiation. Critical time points were used to identify a switch from the activity of cell proliferation genes to myogenic structural genes. 15-20 adult zebrafish dorsal skeletal muscles were isolated at each of 6 distinct time points (day 0, day 1, day 4, day 7, day 10, day 14) in replicates.