Mitochondrial DNA Mutations and Age-Related Muscle Loss

What are Mitochondria?

• Definition: Mitochondria are membrane-bound organelles present in the cytoplasm of most eukaryotic cells, often called the “powerhouses” of the cell.
• Maternal inheritance: Mitochondria are inherited exclusively from the mother via the egg cell.

Key functions:

• Energy production: Generate adenosine triphosphate (ATP), the primary energy carrier required for muscle contraction, protein synthesis, and cell division.
• Cellular respiration: Facilitates the breakdown of food into energy in the form of ATP.
• Regulating cell death: Control apoptosis, ensuring the maintenance of healthy tissues.
• Mitochondrial DNA (mtDNA): Contains its DNA, which is prone to mutations that significantly affect cellular functions.

Key Findings of the Study

• Deletion mutation’s role: Deletion mutations in mtDNA reduce its size and functionality, gradually eroding mitochondrial efficiency.
  • These mutated mtDNA molecules outcompete healthy ones, leading to a decline in ATP production.
• Chimeric genes: Deletion mutations create chimeric genes by fusing different mitochondrial genes, forming abnormal sequences.
  • Chimeric genes disrupt mtDNA expression, accelerating mitochondrial dysfunction and muscle degradation.
• Age-related changes: Older individuals exhibit a two-fold increase in chimeric mitochondrial mRNA, correlating with biological ageing.
  • Mutations also affect brain and muscle tissues, emphasizing their systemic impact on ageing.
• Biomarkers for biological ageing: mtDNA deletion mutations and chimeric mRNA are key indicators of biological ageing.
  • Understanding these markers could pave the way for therapies to prevent or repair mutations, delaying age-related muscle loss.

Source: TH

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