Project description:In this study, we used C3H/10T1/2 cells, a well known model of myogenic conversion, to study the effect of Six4 knockdown on the expression of genes during fibroblasts to myocytes conversion induced by ectopic expression of MyoD We established C3H/10T1/2 cell line with stable Six4 knockdown by short hairpin RNA (shSix4) vs a control cell line (shLuc) and converted these cells into myogenic lineage by retroviral transduction of plasmid encoding Flag-MyoD-myc (pBABE-MyoD) or empty plasmid (pBABE). Cells were then induced to differentiate for 24 hours before RNA extraction.
Project description:In this study, we used C3H/10T1/2 cells, a well known model of myogenic conversion, to study the effect of Six4 knockdown on the expression of genes during fibroblasts to myocytes conversion induced by ectopic expression of MyoD
Project description:Direct lineage reprogramming provides a unique system to study cell fate transitions and unearth molecular mechanisms that safeguard cellular identity. We previously reported on direct conversion of mouse fibroblasts into induced myogenic progenitor cells (iMPCs) by transient MyoD overexpression in concert with small molecules treatment. Here we employed integrative multi-omic approaches to delineate the molecular landscape of fibroblast reprogramming into iMPCs in comparison to transdifferentiation into myogenic cells solely by MyoD overexpression. Utilizing bulk RNA-sequencing and mass spectrometry, we uncovered molecular regulators and pathways that endow a myogenic stem cell identity on fibroblasts only in the presence of small molecule treatment. In addition, we demonstrate that Pax7+ cells in iMPCs share molecular attributes with myoblasts, however in addition express unique genes, proteins and pathways that are indicative of a more activated satellite cell-like state in vitro. Collectively, this study charts a molecular blueprint for reprogramming fibroblasts into muscle stem and progenitor cells and further establishes the fidelity of stable iMPC cultures in capturing skeletal muscle regeneration in vitro for disease modeling and basic research applications.
Project description:Synthetic transcription factors can be applied to many areas of biotechnology, medicine, and basic research. Currently, the most common method for engineering synthetic transcription factors has been based on programmable DNA-binding domains of zinc finger proteins, Transcription Activator-Like Effectors (TALEs), and most recently the CRISPR/Cas9 system. These transcription factor platforms consist of the DNA-binding domain fused to potent transcriptional activation domains, most commonly the tetramer of the minimal transactivation domain of the VP16 protein from herpes simplex virus, referred to as VP64. Although many applications are well-suited for the targeted activation of a single gene, genetic reprogramming requires the coordinated regulation of many nodes of natural gene networks as is typically performed by naturally occurring reprogramming factors. Thus we sought to combine principles from each of these approaches by attaching potent transcriptional activation domains to a natural reprogramming factor to increase the efficiency and/or rate of cell fate conversion. In this study, we evaluated the effects of fusing potent activation domains to the transcription factor MyoD, the master regulator of the skeletal myoblast lineage. In certain non-myogenic lineages, MyoD overexpression causes upregulation of the myogenic gene network and conversion to a myoblast phenotype including cell fusion into multinucleated myotubes. Compared to wild-type MyoD, the VP64-MyoD fusion protein induced greater overall reprogramming of global gene expression. This simple approach for increasing the potency of natural reprogramming factors circumvents the need for screening engineered proteins and leads to a more robust cellular reprogramming compared to treatment with the wild type transcription factor. Human dermal fibroblasts were transduced with a single tet inducible lentivirus that expresses either WT-MyoD or VP64-MyoD in response to treatment with doxycycline. Untreated human dermal fibroblast served as the negative control. Gene expression was measured using mRNA-seq, and differential expression was calculated using DESeq. All experiments were performed in biological duplicates.
Project description:Rhabdomyosarcoma (RMS) is a frequent non-epithelial tumor of soft tissue that originates from a myogenic differentiation defect. Expression of SNAIL transcription factor is elevated in the alveolar subtype of RMS, characterized by a low myogenic differentiation status and high aggressiveness. SNAIL affects RMS metastasis by reorganization of actin cytoskeleton, regulation of ezrin expression and chemotaxis to HGF and SDF-1. The differentiation of human RMS diminishes SNAIL level. SNAIL silencing completely abolishes the growth of human RMS xenotransplants. SNAIL inhibits myogenic differentiation of RMS by binding to the MYF5 promoter, suppressing its expression, displacing MYOD from canonical to alternative E-box sequences and regulating myomiRs expression. SNAIL silencing allows the re-expression of MYF5 and canonical MYOD binding, promoting RMS cell myogenic differentiation. These novel results open potential avenues for the development of innovative therapeutic strategies based on SNAIL silencing.
Project description:The ability to recapitulate muscle differentiation in vitro has proven invaluable to investigate mechanisms of myogenesis, muscle cell function and muscle diseases. However, obtaining myoblasts from patients with neuromuscular diseases poses ethical and procedural challenges which limit investigations of molecular mechanisms of muscle pathophysiology. Alternative myogenic models have been developed, such as the derivation of myogenic cells from skin fibroblasts through activation of an endogenous myogenic program triggered by exogenous expression of murine Myod. In the context of this RNA-seq dataset, we compare the transcriptome of myo-converted human fibroblasts and isogenic in vitro differentiated myoblasts. We show that myogenic induction of fibroblasts elicits genome-wide transcriptomic changes indicative of strong myogenic commitment and differentiation, including marked upregulation of genes implicated in cell cycle exit and in several myogenic pathways. Yet, we find that myotubes are further along myogenic commitment than myo-converted fibroblasts under the conditions tested. Extension of myo-conversion to 7 days does not significantly enhance myogenic commitment, from a gene expression standpoint. This suggests that myo-converted fibroblasts and myotubes retain some cell type specificity of gene expression profiles. Although these myogenic cell types are not identical, our results nonetheless favor a view of myo-converted fibroblasts as a robust and practical model to investigate cellular and genomic properties of cells from patients with muscle pathologies.
Project description:MyoD is known to transdifferentiate fibroblasts into muscle-like cells. Despite phenotypic resemblance and expression of myogenic marker genes in transdifferentiated cells, our global gene expression data suggests that ~100 genes, many involved in muscle development and function, remain non-reprogrammed. To understand this incomplete reprogramming, we characterized genome-wide chromatin accessibility and MyoD binding in human primary myoblasts and in MyoD-induced skin fibroblast cells. Our analyses revealed thousands of sites with incomplete chromatin reprogramming.Combined analyses of gene expression and epigenetic profiles revealed that many myogenic genes not upregulated during the transdifferentiation process have undergone MyoD-dependent chromatin remodeling, but to a significantly lower extent than reprogrammed genes. Our findings suggest that incomplete MyoD-induced transdifferentiation is due to chromatin-remodeling deficiencies, and that additional factors are required to transdifferentiate cells into a state more similar to myoblasts.
Project description:MyoD is known to transdifferentiate fibroblasts into muscle-like cells. Despite phenotypic resemblance and expression of myogenic marker genes in transdifferentiated cells, our global gene expression data suggests that ~100 genes, many involved in muscle development and function, remain non-reprogrammed. To understand this incomplete reprogramming, we characterized genome-wide chromatin accessibility and MyoD binding in human primary myoblasts and in MyoD-induced skin fibroblast cells. Our analyses revealed thousands of sites with incomplete chromatin reprogramming.Combined analyses of gene expression and epigenetic profiles revealed that many myogenic genes not upregulated during the transdifferentiation process have undergone MyoD-dependent chromatin remodeling, but to a significantly lower extent than reprogrammed genes. Our findings suggest that incomplete MyoD-induced transdifferentiation is due to chromatin-remodeling deficiencies, and that additional factors are required to transdifferentiate cells into a state more similar to myoblasts.
Project description:MyoD is known to transdifferentiate fibroblasts into muscle-like cells. Despite phenotypic resemblance and expression of myogenic marker genes in transdifferentiated cells, our global gene expression data suggests that ~100 genes, many involved in muscle development and function, remain non-reprogrammed. To understand this incomplete reprogramming, we characterized genome-wide chromatin accessibility and MyoD binding in human primary myoblasts and in MyoD-induced skin fibroblast cells. Our analyses revealed thousands of sites with incomplete chromatin reprogramming.Combined analyses of gene expression and epigenetic profiles revealed that many myogenic genes not upregulated during the transdifferentiation process have undergone MyoD-dependent chromatin remodeling, but to a significantly lower extent than reprogrammed genes. Our findings suggest that incomplete MyoD-induced transdifferentiation is due to chromatin-remodeling deficiencies, and that additional factors are required to transdifferentiate cells into a state more similar to myoblasts.