Project description:The regeneration of skeletal muscle relies on satellite cells which can proliferate, differentiate and form new myofibers upon injury. Emerging evidence suggests that misregulations of satellite cell fate and function influence the severity of Duchenne Muscular Dystrophy (DMD). The myogenic identity and maintenance of the pool of satellite cells is determined by the transcription factor PAX7. Satellite cell proliferation and self-renewal is regulated by the circadian clock. Here, we show that the CLOCK-interacting protein, Circadian (CIPC), a negative-feedback regulator of the circadian clock, is up-regulated during myoblast differentiation. Specific deletion of CIPC in satellite cells alleviated myopathy, improved muscle function and reduced fibrosis in mdx mice. CIPC deficiency led to activation of the ERK1/2 and JNK1/2 signaling pathways, which in turn activated the transcription factor SP1 to trigger the transcription of PAX7. Therefore, CIPC is a negative regulator of satellite cell function and loss of CIPC in satellite cells promotes muscle regeneration.
Project description:The regeneration of skeletal muscle relies on satellite cells which can proliferate, differentiate and form new myofibers upon injury. Emerging evidence suggests that misregulations of satellite cell fate and function influence the severity of Duchenne Muscular Dystrophy (DMD). The myogenic identity and maintenance of the pool of satellite cells is determined by the transcription factor PAX7. Satellite cell proliferation and self-renewal is regulated by the circadian clock. Here, we show that the CLOCK-interacting protein, Circadian (CIPC), a negative-feedback regulator of the circadian clock, is up-regulated during myoblast differentiation. Specific deletion of CIPC in satellite cells alleviated myopathy, improved muscle function and reduced fibrosis in mdx mice. CIPC deficiency led to activation of the ERK1/2 and JNK1/2 signaling pathways, which in turn activated the transcription factor SP1 to trigger the transcription of PAX7. Therefore, CIPC is a negative regulator of satellite cell function and loss of CIPC in satellite cells promotes muscle regeneration.
Project description:Transcriptional profiling of mouse skeletal muscle-derived cells comparing satellite cells with PDGFRa+ cells. Satellite cells and PDGFRa+ cells were directly isolated from diaphragm of dystrophic mdx mouse by FACS. Two-condition experiment, satellite cells vs. PDGFRa+ cells. Freshly isolated. One replicate per array.
Project description:Transcriptional profiling of mouse skeletal muscle-derived cells comparing satellite cells with PDGFRa+ cells. Satellite cells and PDGFRa+ cells were directly isolated from diaphragm of dystrophic mdx mouse by FACS.
Project description:Skeletal muscle has remarkable capacity to regenerate upon injury due to the presence of satellite cells. The maintenance and function of satellite cells are regulated by circadian clock. Cryptocrhome 2 (CRY2) is a key component of the circadian clock and its role in skeletal muscle regeneration remains controversial. Here, we report that CRY2 is down-regulated during muscle regeneration. Using the satellite cell specific CRY2 knockout mice (CRY2scko), we show that deletion of CRY2 enhances muscle regeneration. Single myofiber analysis showed that deletion of CRY2 enhances satellite cell self-renewal. In the absence of CRY2, the ERK1/2 and JNK1/2 signaling pathways become activated, which phosphorylates the transcription factor ETS1, which in turn binds to the promoter of PAX7 to induce its transcription. CRY2 deficient myoblasts survived better in ischemic muscle. Deletion of CRY2 also alleviated myopathy in mdx mice. Therefore, CRY2 plays an essential role in regulating satellite cell function and skeletal muscle regeneration.
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:In response to skeletal muscle injury, adult myogenic stem cells, known as satellite cells, are activated and undergo proliferation and differentiation to regenerate new muscle fibers. The skeletal muscle-specific microRNA, miR-206, is up-regulated in satellite cells following muscle injury, but its role in muscle regeneration has not been defined. Here we show that skeletal muscle regeneration in response to cardiotoxin injury is impaired in mice lacking miR-206. Loss of miR-206 also accelerates and exacerbates the dystrophic phenotype of mdx mice, a model for Duchenne muscular dystrophy. MiR-206 promotes satellite cell differentiation and fusion to form multinucleated myofibers by suppressing a collection of negative regulators of myogenesis. Our findings reveal an essential role for miR-206 in satellite cell differentiation during skeletal muscle regeneration and as a modulator of Duchenne muscular dystrophy. total RNA obtained from TA muscle of mdx and 3 miR-206 KO; mdx mice at 3 months of age.
Project description:The satellite cell of skeletal muscle provides a paradigm for quiescent and activated tissue stem cell states. We have carried out transcriptome analyses by comparing satellite cells from adult skeletal muscles, where they are mainly quiescent, with cells from growing muscles, regenerating (mdx) muscles, or with cells in culture, where they are activated. Our study gives new insights into the satellite cell biology during activation and in respect with its niche. We used microarrays to study the global programme of gene expression underlying adult satellite cell quiescence compared to activation states and to identify distinct classes of up-regulated genes in these two different states Skeletal muscle satellite cells were isolated by flow cytrometry using the GFP fluorescence marker from Pax3GFP/+ mice skeletal muscle. The transcriptome of quiescent satellite cells from adult Pax3GFP/+ muscle was compared to the transcriptome of activated satellite cells obtained from three different samples: 1) regenerating Pax3GFP/+:mdx/mdx muscle (Ad.mdx) , 2) growing 1 week old Pax3GFP/+ muscle (1wk), and 3) adult Pax3GFP/+ cells after 3 days in culture (Ad.cult).
Project description:Introduction: Skeletal muscle satellite cells (MuSCs, or stem cells) play a crucial role in muscle development, maintenance, and regeneration, serving both hypertrophic support and regenerative myogenesis. Syndecans (SDCs) act as communication bridges within the muscle microenvironment, regulating interactions with extracellular matrix components, and contributing significantly to tissue repair and inflammation. Specifically, syndecan-4 (SDC4) is involved in muscle regeneration at multiple stages. Methods: This study delves into the emerging challenge of wooden breast (WB) myopathy and its connection to SDC4. Our hypothesis proposes that disruptions in MuSC dynamics through SDC4 contribute to the increased incidence of breast myopathies observed in growing broilers. To test our hypothesis, non-affected and affected broilers were systematically selected, and the characteristics of WB myopathy were studied both in vitro and in vivo. SDC4 overexpression in MuSCs and blocking peptides corresponding to the SDC4 ectodomain were used for investigation of the role of SDC4 in muscle development and its shedding levels. Results and Discussion: Examination in vivo of affected muscles revealed smaller fibers and changes in metabolic pathways. In vitro studies unveiled disrupted proliferation of MuSCs in WB myopathy, accompanied by downregulation of several muscle markers. Investigation of a potentially role of SDC4 in the pathogenesis of WB myopathy revealed a decreased tendency in SDC4 gene expression and increased shedding of its ectodomain. Moreover, we showed that SDC4 overexpression is linked to decreased proliferation in MuSCs and affected myogenesis. We detected the impairment proliferation of WB-affected MuSCs, revealing critical insights into the dysfunctional state of these cells in myopathy. Additionally, by treating MuSCs with blocking peptides derived from the SDC4 ectodomain, we identified altered proliferation. Taken together, this work contributes valuable knowledge on the molecular mechanisms underlying WB myopathy and role of SDC4 in this chicken myopathy.