Selective elimination of mitochondrial mutations in the germline by genome editing

Area of Science:

• Genetics
• Molecular Biology
• Reproductive Medicine

Background:

• Mitochondrial diseases are maternally inherited genetic disorders caused by mutations in mitochondrial DNA (mtDNA).
• Most patients exhibit mtDNA heteroplasmy, the coexistence of mutated and wild-type mtDNA.
• Preventing germline transmission of these diseases is a significant challenge.

Purpose of the Study:

• To develop and demonstrate a strategy for preventing the germline transmission of mitochondrial diseases.
• To induce a shift in mtDNA heteroplasmy by selectively eliminating mutated mtDNA.
• To establish a potential therapeutic approach for inherited mitochondrial disorders.

Main Methods:

• Utilized mitochondria-targeted restriction endonucleases and TALENs in NZB/BALB heteroplasmic mice to prevent germline transmission.
• Applied mitochondria-targeted TALENs (mito-TALENs) to reduce mutated human mtDNA levels in mammalian oocytes.
• Targeted specific mutations responsible for Leber's hereditary optic neuropathy (LHON) and neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP).

Main Results:

• Successfully prevented germline transmission of mtDNA haplotypes in heteroplasmic mice.
• Demonstrated a significant reduction in mutated human mtDNA levels associated with LHON and NARP in oocytes.
• Validated the efficacy of mito-TALENs in selectively eliminating mutated mtDNA.

Conclusions:

• The developed strategy offers a potential therapeutic avenue for preventing the transgenerational inheritance of mitochondrial diseases.
• Selective elimination of mutated mtDNA through engineered nucleases can correct mtDNA heteroplasmy.
• This approach holds promise for future interventions against inherited mitochondrial disorders.