Related Experiment Video
Updated: Nov 26, 2025
Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Mitochondrial dysfunction and consequences in calpain-3-deficient muscle
Vanessa E Jahnke1, Jennifer M Peterson2, Jack H Van Der Meulen1
1Center for Genetic Medicine Research, Children's National Research Institute, Children's National Hospital, Washington, D.C., USA.
Background:
Nonsense or loss-of-function mutations in the non-lysosomal cysteine protease calpain-3 result in limb-girdle muscular dystrophy type 2A (LGMD2A). While calpain-3 is implicated in muscle cell differentiation, sarcomere formation, and muscle cytoskeletal remodeling, the physiological basis for LGMD2A has remained elusive.
Methods:
Cell growth, gene expression profiling, and mitochondrial content and function were analyzed using muscle and muscle cell cultures established from healthy and calpain-3-deficient mice. Calpain-3-deficient mice were also treated with PPAR-delta agonist (GW501516) to assess mitochondrial function and membrane repair. The unpaired t test was used to assess the significance of the differences observed between the two groups or treatments. ANOVAs were used to assess significance over time.
Results:
We find that calpain-3 deficiency causes mitochondrial dysfunction in the muscles and myoblasts. Calpain-3-deficient myoblasts showed increased proliferation, and their gene expression profile showed aberrant mitochondrial biogenesis. Myotube gene expression analysis further revealed altered lipid metabolism in calpain-3-deficient muscle. Mitochondrial defects were validated in vitro and in vivo. We used GW501516 to improve mitochondrial biogenesis in vivo in 7-month-old calpain-3-deficient mice. This treatment improved satellite cell activity as indicated by increased MyoD and Pax7 mRNA expression. It also decreased muscle fatigability and reduced serum creatine kinase levels. The decreased mitochondrial function also impaired sarcolemmal repair in the calpain-3-deficient skeletal muscle. Improving mitochondrial activity by acute pyruvate treatment improved sarcolemmal repair.
Conclusion:
Our results provide evidence that calpain-3 deficiency in the skeletal muscle is associated with poor mitochondrial biogenesis and function resulting in poor sarcolemmal repair. Addressing this deficit by drugs that improve mitochondrial activity offers new therapeutic avenues for LGMD2A.
Insights
Calpain-3 deficiency causes mitochondrial dysfunction and impaired muscle repair in limb-girdle muscular dystrophy type 2A (LGMD2A). Treatments improving mitochondrial activity show therapeutic potential for LGMD2A patients.
Area of Science:
- Biochemistry
- Molecular Biology
- Muscle Physiology
Background:
- Nonsense or loss-of-function mutations in calpain-3 cause limb-girdle muscular dystrophy type 2A (LGMD2A).
- The precise physiological mechanisms underlying LGMD2A pathogenesis remain unclear despite calpain-3's known roles in muscle.
- Calpain-3's involvement in muscle differentiation, sarcomere formation, and cytoskeletal remodeling is established.
Purpose of the Study:
- To investigate the physiological basis of LGMD2A by examining muscle and myoblast function in calpain-3-deficient mice.
- To assess the impact of calpain-3 deficiency on mitochondrial content, function, and gene expression.
- To evaluate the therapeutic potential of enhancing mitochondrial activity in LGMD2A models.
Main Methods:
- Analyzed muscle and myoblast cultures from wild-type and calpain-3-deficient mice.
- Performed gene expression profiling and assessed mitochondrial content and function.
- Treated calpain-3-deficient mice with a PPAR-delta agonist (GW501516) and pyruvate to evaluate mitochondrial function and membrane repair.
- Utilized unpaired t tests and ANOVAs for statistical analysis.
Main Results:
- Calpain-3 deficiency led to mitochondrial dysfunction, increased myoblast proliferation, and aberrant mitochondrial biogenesis.
- Altered lipid metabolism and impaired sarcolemmal repair were observed in calpain-3-deficient muscle.
- GW501516 treatment improved mitochondrial biogenesis, satellite cell activity, and reduced muscle fatigability and creatine kinase levels.
- Pyruvate treatment enhanced sarcolemmal repair in calpain-3-deficient muscle.
Conclusions:
- Calpain-3 deficiency in skeletal muscle is linked to impaired mitochondrial biogenesis and function, leading to poor sarcolemmal repair.
- Mitochondrial dysfunction is a key contributor to LGMD2A pathology.
- Therapies targeting mitochondrial activity present promising therapeutic strategies for LGMD2A.
More Related Videos
Related Concept Videos
01:48ATP Synthase: Mechanism
01:21Satellite Stem Cells and Muscular Dystrophy