Exercise based Intervention For Metabolic Inflexibility Linked With Lipid Storage Myopathy Using Innovative CRISPR...

Area of Science:

• Biochemistry
• Genetics
• Mitochondrial Biology

Background:

• Multiple acyl-CoA dehydrogenase deficiency (MADD) is a genetic disorder affecting fatty acid metabolism and mitochondrial function.
• It leads to progressive neuromuscular and cardiac issues, often caused by mutations in electron transfer flavoprotein dehydrogenase (ETFDH).
• ETFDH dysfunction disrupts electron transport, increases reactive oxygen species (ROS), and impairs energy production.

Purpose of the Study:

• To investigate the role of redox imbalance in MADD pathogenesis.
• To create and characterize a CRISPR/Cas9-based *Drosophila melanogaster* model of MADD with patient-relevant ETFDH mutations.
• To explore potential therapeutic interventions, specifically exercise, in this MADD model.

Main Methods:

• Generated CRISPR/Cas9 knock-in *Drosophila melanogaster* models with specific ETFDH missense mutations.
• Assessed locomotor and cardiac function, muscle performance, and lipid accumulation in mutant flies.
• Performed *in vivo* respirometry, measured ROS levels, ATP content, and key signaling pathway markers (AMPK, PGC-1α, Tfam).
• Evaluated the impact of endurance exercise on MADD phenotypes.

Main Results:

• Mutant flies exhibited progressive locomotor and cardiac dysfunction, muscle weakness, and significant lipid accumulation.
• Impaired mitochondrial respiration (decreased oxygen consumption) and elevated ROS levels were observed.
• Molecular analyses revealed ATP depletion and activation of energy stress pathways, suggesting compensatory mitochondrial biogenesis.
• Endurance exercise significantly ameliorated MADD phenotypes, including improved function and reduced oxidative stress and lipid burden.

Conclusions:

• Established a *Drosophila* model that recapitulates key features of MADD, highlighting the role of redox imbalance.
• Identified oxidative stress as a central mechanism in MADD pathology.
• Demonstrated that endurance exercise can be a beneficial therapeutic strategy for MADD by mitigating oxidative stress and improving metabolic function.