Recovery of MERRF fibroblasts and cybrids pathophysiology by coenzyme Q10

Area of Science:

• Genetics
• Cell Biology
• Biochemistry

Background:

• Mitochondrial DNA (mtDNA) mutations are linked to human diseases with limited treatment options.
• Myoclonic epilepsy with ragged-red fibers (MERRF) is a common mitochondrial disorder caused by mtDNA point mutations, often in tRNA genes.
• The prevalent m.8344A>G mutation in the MT-TK gene disrupts mitochondrial protein translation and electron transport chain assembly.

Purpose of the Study:

• To investigate the impact of the m.8344A>G mtDNA mutation on mitochondrial function in patient-derived cells.
• To assess the potential of Coenzyme Q10 (CoQ10) as a therapeutic agent for MERRF-related mitochondrial dysfunction.

Main Methods:

• Establishment and analysis of primary fibroblast cultures from MERRF patients with the A8344G mutation.
• Utilized transmitochondrial cybrids harboring the A8344G mutation for further investigation.
• Measured Coenzyme Q10 levels, mitochondrial respiratory chain activity, and protein expression.
• Performed Mitotracker staining and imaging to analyze mitochondrial morphology and membrane potential.
• Assessed oxidative stress and mitophagy levels.
• Evaluated the effects of CoQ10 supplementation on cellular and mitochondrial parameters.

Main Results:

• MERRF fibroblasts and cybrids exhibited significantly reduced Coenzyme Q10 levels, impaired respiratory chain activity, and altered mitochondrial protein expression.
• Mitochondrial dysfunction was characterized by small, rounded, depolarized mitochondria, increased oxidative stress, and enhanced mitophagy.
• CoQ10 supplementation partially restored mitochondrial function and reduced mitophagy in patient-derived cells and cybrids.

Conclusions:

• The m.8344A>G mutation severely impacts mitochondrial function, leading to CoQ10 deficiency, oxidative stress, and increased mitophagy.
• Patient-derived fibroblasts and cybrids serve as valuable models for studying MERRF pathogenesis.
• CoQ10 supplementation shows promise in ameliorating MERRF-associated mitochondrial defects, suggesting its potential role in therapeutic strategies and drug screening.