A Mechanistic basis of fast myofiber vulnerability in neuromuscular diseases [Multiome]
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ABSTRACT:
PROVIDER: PRJNA1268479 | ENA |
REPOSITORIES: ENA
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Project description:Skeletal muscle denervation is a characteristic feature of neuromuscular diseases such as amyotrophic lateral sclerosis (ALS) and sarcopenia, leading to atrophy, loss of muscle strength, and poor patient outcomes. Myofibers are typically classified into slow oxidative and fast glycolytic types based on their contractile and metabolic properties. Neuromuscular diseases predominantly affect fast myofibers, while slow myofibers are relatively spared. However, the mechanisms underlying the heightened susceptibility of fast myofibers to disease and atrophy remain unclear. To investigate this, we analyzed the transcriptional profiles of innervated and denervated myonuclei. Our findings revealed that the fast muscle gene program and the transcription factor Maf are repressed during denervation. Notably, overexpression of Maf in the skeletal muscles of mice prevented loss of muscle mass and myofiber atrophy caused by denervation. Single-nucleus RNA sequencing and ATAC sequencing demonstrated that Maf overexpression reprogrammed denervated myonuclei by repressing atrophic gene programs and reactivating fast muscle gene expression. Similar repression of fast muscle genes and Maf was observed in muscles from mice and humans with ALS. Consistent with these findings, Maf overexpression in human skeletal muscle cells induced the expression of fast muscle genes while suppressing atrophic gene expression. Our findings highlight a key role for Maf in maintaining muscle mass and demonstrate that its repression contributes to the progression of neuromuscular diseases in both mice and humans. Modulating Maf activity could offer a promising therapeutic strategy to preserve skeletal muscle function during disease, aging, or injury.
2025-05-29 | GSE298184 | GEO
Project description:A Mechanistic basis of fast myofiber vulnerability in neuromuscular diseases [snRNA-seq]
| PRJNA1268492 | ENA
Project description:Skeletal muscle denervation is a characteristic feature of neuromuscular diseases such as amyotrophic lateral sclerosis (ALS) and sarcopenia, leading to atrophy, loss of muscle strength, and poor patient outcomes. Myofibers are typically classified into slow oxidative and fast glycolytic types based on their contractile and metabolic properties. Neuromuscular diseases predominantly affect fast myofibers, while slow myofibers are relatively spared. However, the mechanisms underlying the heightened susceptibility of fast myofibers to disease and atrophy remain unclear. To investigate this, we analyzed the transcriptional profiles of innervated and denervated myonuclei. Our findings revealed that the fast muscle gene program and the transcription factor Maf are repressed during denervation. Notably, overexpression of Maf in the skeletal muscles of mice prevented loss of muscle mass and myofiber atrophy caused by denervation. Single-nucleus RNA sequencing and ATAC sequencing demonstrated that Maf overexpression reprogrammed denervated myonuclei by repressing atrophic gene programs and reactivating fast muscle gene expression. Similar repression of fast muscle genes and Maf was observed in muscles from mice and humans with ALS. Consistent with these findings, Maf overexpression in human skeletal muscle cells induced the expression of fast muscle genes while suppressing atrophic gene expression. Our findings highlight a key role for Maf in maintaining muscle mass and demonstrate that its repression contributes to the progression of neuromuscular diseases in both mice and humans. Modulating Maf activity could offer a promising therapeutic strategy to preserve skeletal muscle function during disease, aging, or injury.
2025-05-29 | GSE298187 | GEO
Project description:Myofiber size regulation is critical in health, disease, and aging. MuSK (muscle-specific kinase) is a BMP (bone morphogenetic protein) co-receptor that promotes and shapes BMP signaling that is expressed at all neuromuscular junctions and is also present extrasynaptically in the slow soleus muscle. To investigate the role of the MuSK-BMP pathway in vivo we generated mice lacking the BMP-binding MuSK Ig3 domain. These ∆Ig3-MuSK mice are viable and fertile with innervation levels comparable to wild type. In 3-month-old mice myofibers are smaller in the slow soleus, but not in the fast TA. Here we use bulk RNA-seq to perform transcriptomic analysis of slow and fast mouse muscle. RNAseq analysis revealed soleus-selective decreases in RNA metabolism and protein synthesis pathways as well as dysregulation of IGF1 pathway components. Moreover, Akt-mTOR signaling is reduced in soleus but not TA. We propose that the MuSK-BMP pathway acts extrasynaptically to maintain myofiber size in slow muscle by promoting protein synthetic pathways including the IGF1-Akt-mTOR signaling. These results reveal a novel mechanism for regulating myofiber size in slow muscle and introduce the MuSK-BMP pathway as a target for promoting muscle growth and combatting atrophy.
2024-01-10 | GSE212352 | GEO
Project description:Skeletal muscles are complex organs consisting of multiple tissues, including connective tissue, blood vessels, nerves and multinucleated myofibers. Single-nucleus transcriptomics analyses have revealed distinctive myonuclear populations related to myofiber type and to specialized regions, including neuromuscular and myotendinous junctions. However, the use of tissue dissociation methods prevented access to global spatial organization. Here we applied RNA tomography (TOMOseq), a spatial transcriptomics approach, to explore gene expression differences along murine tibialis anterior muscles.
2024-09-19 | GSE253441 | GEO
Project description:During aging and neuromuscular diseases, there is a progressive loss of skeletal muscle volume and function, which is often associated with denervation and a loss of muscle stem cells (MuSCs). A relationship between MuSCs and innervation has not been established however. Herein, we administered neuromuscular trauma to a MuSC lineage tracing model and observed a subset of MuSCs specifically engraft in a position proximal to the neuromuscular junction (NMJ). In aging and in a model of neuromuscular degeneration (Sod1-/-), this localized engraftment behavior was reduced. Genetic rescue of motor neurons in Sod1-/- mice reestablished integrity of the NMJ and partially restored MuSC ability to engraft into NMJ proximal positions. Using single cell RNA-sequencing of MuSCs, we demonstrate that a subset of MuSCs are molecularly distinguishable from MuSCs responding to myofiber injury. These data reveal unique features of MuSCs that respond to synaptic perturbations caused by aging and other stressors.
2021-05-06 | GSE165978 | GEO
Project description:Heart failure with preserved ejection fraction (HFpEF) is characterised by a distinct but poorly understood in skeletal muscle pathology. In a rat model ZSF1, we identify impaired myonuclear accretion as a mechanism for ablated myofiber growth in HFpEF following resistance exercise intervention. Muscle vascular or mitochondrial dysfunction, or impaired protein synthesis signalling, do not appear as primary limiting mechanisms, and cardiac therapies do not attenuate skeletal muscle pathology. However, we identify that acute caloric restriction rejuvenates myofiber growth in HFpEF during resistance exercise intervention.
2025-01-19 | E-MTAB-12494 | biostudies-arrayexpress
Project description:Skeletal muscle fibers are large syncytia but it is currently unknown whether gene expression is coordinately regulated in their numerous nuclei. By snRNA-seq and snATAC-seq, we showed that slow, fast, myotendinous and neuromuscular junction myonuclei each have different transcriptional programs, associated with distinct chromatin states and combinations of transcription factors. In adult mice, identified myofiber types predominantly express either a slow or one of the three fast isoforms of Myosin heavy chain (MYH) proteins, while a small number of hybrid fibers can express more than one MYH. By snRNA-seq and FISH, we showed that the majority of myonuclei within a myofiber are synchronized, coordinately expressing only one fast Myh isoform with a preferential pane of muscle-specific genes. Importantly, this coordination of expression occurs early during post-natal development and depends on innervation. These findings highlight a unique mechanism of coordination of gene expression in a syncytium.
2020-05-08 | GSE150065 | GEO
Project description:Decline in skeletal muscle cell size (myofiber atrophy) is a key feature of cancer-induced wasting (cachexia). In particular, atrophy of the diaphragm, the major muscle responsible for breathing, is an important determinant of cancer-associated mortality. However, therapeutic options are limited. Here, we have used Drosophila transgenic screening to identify muscle-secreted factors (myokines) that act as paracrine regulators of myofiber growth. Subsequent testing in mouse myotubes revealed that mouse Fibcd1 is an evolutionary-conserved myokine that preserves myofiber size via ERK signaling. Local administration of recombinant Fibcd1 (rFibcd1) ameliorates cachexia-induced myofiber atrophy in the diaphragm of mice bearing patient-derived melanoma xenografts and LLC carcinomas. Moreover, rFibcd1 impedes cachexia-associated transcriptional changes in the diaphragm. Fibcd1-induced signaling appears to be muscle selective because rFibcd1 increases ERK activity in myotubes but not in several cancer cell lines tested. We propose that rFibcd1 may help reinstate myofiber size in the diaphragm of patients with cancer cachexia.
2022-02-28 | GSE183833 | GEO
Project description:Decline in skeletal muscle cell size (myofiber atrophy) is a key feature of cancer-induced wasting (cachexia). In particular, atrophy of the diaphragm, the major muscle responsible for breathing, is an important determinant of cancer-associated mortality. However, therapeutic options are limited. Here, we have used Drosophila transgenic screening to identify muscle-secreted factors (myokines) that act as paracrine regulators of myofiber growth. Subsequent testing in mouse myotubes revealed that mouse Fibcd1 is an evolutionary-conserved myokine that preserves myofiber size via ERK signaling. Local administration of recombinant Fibcd1 (rFibcd1) ameliorates cachexia-induced myofiber atrophy in the diaphragm of mice bearing patient-derived melanoma xenografts and LLC carcinomas. Moreover, rFibcd1 impedes cachexia-associated transcriptional changes in the diaphragm. Fibcd1-induced signaling appears to be muscle selective because rFibcd1 increases ERK activity in myotubes but not in several cancer cell lines tested. We propose that rFibcd1 may help reinstate myofiber size in the diaphragm of patients with cancer cachexia.
2022-02-28 | GSE158581 | GEO