Chimeric mitochondrial RNA transcripts predict mitochondrial genome deletion mutations in mitochondrial genetic...

Area of Science:

• Mitochondrial genetics
• Transcriptomics
• Molecular biology

Background:

• Mitochondrial DNA (mtDNA) deletion mutations are linked to incurable diseases and aging.
• The transcriptional products arising from these mtDNA structural variants are poorly understood.

Purpose of the Study:

• To investigate whether mitochondrial genomes with deletion mutations express chimeric mitochondrial RNAs.
• To determine if chimeric mitochondrial RNA frequency correlates with disease and aging.
• To assess the utility of chimeric mitochondrial RNAs as biomarkers for mitochondrial pathology and age-related metabolic changes.

Main Methods:

• Analysis of human and rat RNA sequencing data to identify, quantitate, and characterize chimeric mitochondrial RNAs.
• Induction of mtDNA deletion mutations in rat skeletal muscle using guanidinopropionic acid.
• Correlation of chimeric mitochondrial transcript frequency with DNA-based mutation assays.
• Assessment of the predictive value of chimeric mitochondrial transcripts for nuclear and mitochondrial gene expression.

Main Results:

• Increased frequency of chimeric mitochondrial RNAs observed in patients with mitochondrial genetic diseases and in aged humans.
• The pattern of chimeric mitochondrial transcripts mirrors known mtDNA deletion mutation patterns.
• mtDNA deletion induction in rats led to increased chimeric mitochondrial transcript frequency, correlating with DNA mutation assays.
• Chimeric mitochondrial transcript frequency predicts the expression of key nuclear and mitochondrial genes involved in mitochondrial function.

Conclusions:

• Chimeric mitochondrial RNAs are expressed from mitochondrial genomes containing deletion mutations.
• Chimeric mitochondrial RNAs serve as accessible, orthogonal biomarkers for mitochondrial DNA mutations and pathology.
• Chimeric mitochondrial RNAs can be used to measure age-induced metabolic changes and identify mitochondrial dysfunction.