Pathological Sequelae Associated with Skeletal Muscle Atrophy and Histopathology in G93A*SOD1 Mice

Area of Science:

• Neuroscience
• Muscle Biology
• Genetics

Background:

• Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by motor neuron loss and muscle atrophy.
• The G93A*SOD1 mouse model is widely used for ALS research, expressing a mutant form of human superoxide dismutase 1.
• Previous studies have not fully detailed skeletal muscle pathology in this model.

Purpose of the Study:

• To comprehensively analyze skeletal muscle pathology in G93A*SOD1 mice.
• To investigate the expression pattern and consequences of mutant SOD1 in muscle.
• To identify molecular and ultrastructural changes contributing to muscle dysfunction.

Main Methods:

• Histological, molecular, ultrastructural, and biochemical analyses of skeletal muscles from G93A*SOD1 mice.
• Assessment of mutant SOD1 expression, MuRF1 levels, collagen deposition, and myopathic changes.
• Analysis of signaling pathways, mitochondrial function, and protein levels.

Main Results:

• Increased and differential mutant SOD1 expression correlated with muscle atrophy and elevated MuRF1.
• Significant collagen deposition and myopathic changes were observed, alongside reduced muscle strength.
• Altered protein levels in inflammation, mitochondrial transport, lipid uptake, and antioxidant pathways were detected.
• Mutant SOD1 localized to mitochondria, leading to abnormal mitochondria, altered OXPHOS/PDH levels, and impaired respiration.

Conclusions:

• Skeletal muscle pathology in G93A*SOD1 mice results from ubiquitous mutant SOD1 expression.
• Mutant SOD1 contributes to muscle atrophy, fibrosis, and mitochondrial dysfunction.
• These findings provide a detailed understanding of muscle pathology in a key ALS mouse model.