Mitochondrial mutations alter endurance exercise response and determinants in mice.

Area of Science:

• Mitochondrial biology and genetics
• Exercise physiology
• Metabolic disorders

Background:

• Primary mitochondrial diseases (PMDs) stem from mutations in mitochondrial (mtDNA) or nuclear (nDNA) genes.
• Current PMD therapies are limited; exercise is a potential but poorly understood intervention.
• Exercise improves mitochondrial function in healthy individuals but its effects in PMDs are unclear.

Purpose of the Study:

• To investigate the impact of endurance exercise on mouse models of PMDs with distinct mutations.
• To identify molecular pathways correlating with exercise response in PMDs.
• To determine if exercise benefits are mutation-specific in PMDs.

Main Methods:

• Utilized mouse models representing different PMD genetic defects (mtDNA ND6, CO1, ND5; nDNA Ant1).
• Administered a standardized endurance exercise regimen to affected mice.
• Analyzed physiological responses and correlated them with skeletal muscle and heart gene expression profiles.

Main Results:

• Mice with an mtDNA ND6 mutation showed exercise improvements; CO1 mutation mice had fewer benefits; ND5 mutation mice showed no response.
• Mice with nDNA Ant1 deficiency experienced worsened dilated cardiomyopathy with exercise.
• Key pathways identified: oxidative phosphorylation, amino acid metabolism, extracellular matrix structure, and cell cycle regulation.

Conclusions:

• The efficacy of endurance exercise in PMDs is highly dependent on the specific underlying genetic mutation.
• Mitochondrial function plays a critical role in determining exercise capacity and response.
• While variable, results suggest a potential general benefit of exercise in PMDs, necessitating tailored treatment strategies.