ELAC2 mutations cause a mitochondrial RNA processing defect associated with hypertrophic cardiomyopathy

Area of Science:

• Mitochondrial biology
• Molecular genetics
• Human disease genetics

Background:

• The human mitochondrial genome encodes essential components for cellular respiration.
• Mitochondrial RNA (mtRNA) processing is crucial for mitochondrial translation and function.
• Nuclear-encoded gene products, including RNase Z activity from ELAC2, are vital for mtRNA maturation.

Purpose of the Study:

• To investigate the role of ELAC2 in mitochondrial RNA processing.
• To identify genetic causes of infantile hypertrophic cardiomyopathy and complex I deficiency.
• To establish a link between ELAC2 mutations, mtRNA processing defects, and human disease.

Main Methods:

• Genetic analysis of individuals with infantile hypertrophic cardiomyopathy and complex I deficiency.
• Analysis of mtRNA precursor accumulation in patient-derived muscle and fibroblasts.
• Cellular complementation experiments in mutant cell lines.
• Functional validation using a yeast model.

Main Results:

• Identification of mutations in the ELAC2 gene in affected individuals.
• Observation of accumulated mtRNA precursors in patient cells, indicating a processing defect.
• Impaired mitochondrial translation despite normal levels of mature mt-tRNA, mt-mRNA, and mt-rRNA.
• Restoration of RNA processing and mitochondrial function upon complementation.

Conclusions:

• Mutations in ELAC2 cause defects in mitochondrial RNA processing.
• Defective ELAC2 function leads to infantile hypertrophic cardiomyopathy and complex I deficiency.
• This study establishes a direct link between impaired mtRNA processing and human disease pathogenesis.