Project description:Analysis of skeletal muscles with specific knockout (KO) of Phosphatase and tensin homolog (Pten) gene in an animal model of DMD (mdx mice). Pten knockout alleviates myofiber degeneration and restores muscle function in mdx mice.
Project description:We report here on the identification and functional characterization of Sca1-positive muscle interstitial cells that contribute to regeneration or fibroadipogenic degeneration of dystrophic muscles and mediate the beneficial effects of HDAC inhibitors (HDACi) in mdx mice. We found that the phenotype adopted by these cells and their biological activity are influenced by changes in muscle environment. While Sca1-positive muscle interstitial cells from healthy muscles spontaneously adopt a fibro-adipogenic phenotype, Sca1-positive muscle interstitial cells isolated from dystrophic muscles of young mdx mice show a latent myogenic phenotype that is implemented by the exposure to HDACi. Co-culture assays in vitro and co-transplantation experiments in vivo demonstrate that HDACi also improve Sca1-positive muscle interstitial cell ability to enhance the differentiation potential of adjacent satellite cells. Importantly, HDACi-induced myogenic phenotype and pro-regeneration activity were not observed in Sca1-positive muscle interstitial cells isolated from muscles of old mdx mice. The different phenotype of Sca1-positive muscle interstitial cells from mdx mice at different stages of disease progression correlated with the stage-dependent beneficial effect of HDACi, which were effective only at early stages of disease. Transplantation of Sca1-positive muscle interstitial cells isolated from regenerating young muscles into muscles of old mdx mice restored HDACi ability to increase myofiber size. These results indicate that Sca1-positive muscle interstitial cells are key cellular determinants of disease progression and mediate the beneficial effect of HDACi in a mouse model of muscular dystrophy. Isolation of Sca1+ muscle interstitial cells from TSA treated DMD/MDX mice and MuSc from DMD/MDX mice
Project description:We report here on the identification and functional characterization of Sca1-positive muscle interstitial cells that contribute to regeneration or fibroadipogenic degeneration of dystrophic muscles and mediate the beneficial effects of HDAC inhibitors (HDACi) in mdx mice. We found that the phenotype adopted by these cells and their biological activity are influenced by changes in muscle environment. While Sca1-positive muscle interstitial cells from healthy muscles spontaneously adopt a fibro-adipogenic phenotype, Sca1-positive muscle interstitial cells isolated from dystrophic muscles of young mdx mice show a latent myogenic phenotype that is implemented by the exposure to HDACi. Co-culture assays in vitro and co-transplantation experiments in vivo demonstrate that HDACi also improve Sca1-positive muscle interstitial cell ability to enhance the differentiation potential of adjacent satellite cells. Importantly, HDACi-induced myogenic phenotype and pro-regeneration activity were not observed in Sca1-positive muscle interstitial cells isolated from muscles of old mdx mice. The different phenotype of Sca1-positive muscle interstitial cells from mdx mice at different stages of disease progression correlated with the stage-dependent beneficial effect of HDACi, which were effective only at early stages of disease. Transplantation of Sca1-positive muscle interstitial cells isolated from regenerating young muscles into muscles of old mdx mice restored HDACi ability to increase myofiber size. These results indicate that Sca1-positive muscle interstitial cells are key cellular determinants of disease progression and mediate the beneficial effect of HDACi in a mouse model of muscular dystrophy.
Project description:MicroRNA-expression profile of dystrophic single fibers compared to wild type single fibers isolated from different muscles of mdx and C57BL mice. Myofibers were isolated from different muscle types (tibialis, diaphragm and quadriceps) of gender- (male) and age- (3 month old and half) matched wt and dystrophic mice. 9 total samples per animal model (C57BL, mdx), 3 replicates per muscle type.
Project description:Fibro-adipogenic progenitors (FAPs) are emerging cellular components of the skeletal muscle regenerative environment. The alternative functional phenotype of FAPs - either supportive of muscle regeneration or promoting fibro-adipogenic degeneration M-bM-^@M-^S is a key determinant in the pathogenesis of muscular diseases, including Duchenne Muscular Dystrophy (DMD). However, the molecular regulation of FAPs is still unknown. We show here that an M-bM-^@M-^\HDAC-myomiR-BAF60 variant networkM-bM-^@M-^] regulates the functional phenotype of FAPs in dystrophic muscles of mdx mice. Combinatorial analysis of gene expression microarray and genome-wide chromatin remodeling by Nuclease accessibility (NA)-seq revealed that HDAC inhibitors de-repress a M-bM-^@M-^\latentM-bM-^@M-^] myogenic program in FAPs from dystrophic muscles at early stages of disease progression. In these cells HDAC inhibition promoted the expression of two core components of the myogenic transcriptional machinery, MyoD and BAF60C, and upregulated the myomiRs (miRs) 1.2, 133 and 206, which target two alternative BAF60 variants (BAF60A and B) ultimately leading to the activation of a pro-myogenic program at the expense of the fibro-adipogenic phenotype. By contrast, FAPs from dystrophic muscles at late stages of disease progression displayed resistance to HDACi-induced chromatin remodeling at myogenic loci and fail to activate the pro-myogenic phenotype. These results reveal a previously unappreciated disease stage-specific bipotency of mesenchimal cells within the regenerative environment of dystrophic muscles. Resolution of such bi-potency by epigenetic interventions, such as HDACi, provides the molecular rationale for the in situ reprogramming of target cells to promote therapeutic regeneration of dystrophic muscles. Genome-wide chromatin accessibility patterns in FAPs cells derived from mdx mice at different ages treated either with HDAC inhibitor Trichostatin A (TSA) or with vehicle (saline solution) were assessed using NA-seq (PMID: 19289091)
Project description:MicroRNA-expression profile of dystrophic single fibers compared to wild type single fibers isolated from different muscles of mdx and C57BL mice.
Project description:Duchenne muscular dystrophy (DMD) is caused by an out-of-frame mutation in the DMD gene that results in the absence of a functional dystrophin protein, leading to a devastating and progressive lethal muscle-wasting disease. Genetic modifiers have been shown to increase disease severity in DMD mouse models as well as in human patients. Little is known about cellular heterogeneity in skeletal muscle as disease severity increases. To address this, we explored skeletal muscle-resident cell populations in healthy (wt-NSG), dystrophic (mdx-NSG), and severely dystrophic (mdxD2-NSG) mouse models utilizing scRNA-seq. We found an increased frequency of activated fibroblasts, activated fibro-adipogenic progenitor cells, and proinflammatory macrophages in dystrophic and severely dystrophic gastrocnemius muscles. Moreover, in endothelial cells we found an upregulation of extracellular matrix and platelet aggregation genes in dystrophic and severely dystrophic muscles, indicating endothelial cell functional impairment. In summary, this work extends the understanding of the severe nature of DMD, which should be considered when developing regenerative therapeutic avenues for DMD.
Project description:RNA-seq was performed to compare expression pattern of musles taken form two mice strains- mdx and mdx/Runx1f/f, which are double KO carrting a muscle specific ablation of Runx1 using a Myf5-Cre. This comparison revealed the Runx1- responsive gene set in mdx muscles. we could cross this data with prior retrived datd from privous experiments found in this GEO quary, to pinpiont Runx1 target genes in muscle rgeneration
Project description:We report RNA sequencing data from tibialis anterior muscles of 4 month old male wild type C57Bl/6 mice and mdx/mTR mice (generated in the C57Bl/6 background), which lack the dystrophin and telomerase RNA component genes.
Project description:Fibro-adipogenic progenitors (FAPs) are emerging cellular components of the skeletal muscle regenerative environment. The alternative functional phenotype of FAPs - either supportive of muscle regeneration or promoting fibro-adipogenic degeneration – is a key determinant in the pathogenesis of muscular diseases, including Duchenne Muscular Dystrophy (DMD). However, the molecular regulation of FAPs is still unknown. We show here that an “HDAC-myomiR-BAF60 variant network” regulates the functional phenotype of FAPs in dystrophic muscles of mdx mice. Combinatorial analysis of gene expression microarray and genome-wide chromatin remodeling by Nuclease accessibility (NA)-seq revealed that HDAC inhibitors de-repress a “latent” myogenic program in FAPs from dystrophic muscles at early stages of disease progression. In these cells HDAC inhibition promoted the expression of two core components of the myogenic transcriptional machinery, MyoD and BAF60C, and upregulated the myomiRs (miRs) 1.2, 133 and 206, which target two alternative BAF60 variants (BAF60A and B) ultimately leading to the activation of a pro-myogenic program at the expense of the fibro-adipogenic phenotype. By contrast, FAPs from dystrophic muscles at late stages of disease progression displayed resistance to HDACi-induced chromatin remodeling at myogenic loci and fail to activate the pro-myogenic phenotype. These results reveal a previously unappreciated disease stage-specific bipotency of mesenchimal cells within the regenerative environment of dystrophic muscles. Resolution of such bi-potency by epigenetic interventions, such as HDACi, provides the molecular rationale for the in situ reprogramming of target cells to promote therapeutic regeneration of dystrophic muscles.