Related Experiment Video
Updated: Sep 16, 2025

Dissection of Single Skeletal Muscle Fibers for Immunofluorescent and Morphometric Analyses of Whole-Mount Neuromuscular Junctions
Published on: August 14, 2021
A mechanistic basis of fast myofiber vulnerability to neuromuscular diseases
Matthieu Dos Santos1, Svetlana Bezprozvannaya1, John R McAnally1
1Department of Molecular Biology, the Hamon Center for Regenerative Science and Medicine, and Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
Abstract:
Neuromuscular diseases such as amyotrophic lateral sclerosis and sarcopenia cause muscle atrophy, which preferentially affects fast-twitch glycolytic myofibers. The mechanisms underlying the susceptibility of fast myofibers to disease remain unclear. To investigate this, we analyzed the transcriptional profiles of myonuclei from denervated muscle fibers. We found that the fast muscle gene program and the transcription factor Maf were repressed upon denervation. Overexpression of Maf in mice prevented loss of muscle mass caused by denervation by repressing atrophic genes and restoring fast gene expression. Similar repression of fast genes and Maf was observed in muscles from mice and humans with amyotrophic lateral sclerosis. Notably, Maf overexpression in human skeletal muscle cells in vitro prevented muscle atrophy and activated the expression of fast muscle genes. Our findings highlight a key role for Maf in maintaining muscle mass and could offer a promising therapeutic strategy to preserve muscle function during disease, aging, and injury.
Related Concept Videos
Disorders of the Skeletal Muscle
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
Cross-bridge Cycle
Classification of Skeletal Muscle Fibers
Slow-Twitch Muscle Fibers
Slow oxidative, muscle fibers appear red due to large numbers of capillaries and high levels of...
The Neuromuscular Junction
Types of Skeletal Muscle Fibers
Fast-twitch fibers
Fast-twitch fibers, or Type II fibers, are designed for quick, powerful bursts of speed and strength. They reach peak tension within approximately 0.01 seconds following stimulation. Characterized by a large diameter and densely packed myofibrils, these fibers contain...
Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...

