Mitochondria are intracellular organelles that are essential for life and human health. Mutations of mitochondrial DNA (mtDNA) are a major cause of inherited disease affecting ~1/8000 humans, either due to single base substitutions or deletions. MtDNA diseases typically affect the nervous system, causing substantial ill-health and premature death. MtDNA mutations also accumulate in healthy humans, and are associated with common diseases of ageing, including neurodegenerative disorders such as Parkinson’s disease. In both contexts, mtDNA mutations affect critical respiratory chain proteins thereby affecting cell bioenergetics and ATP production. Human cells contain hundreds to thousands of mtDNA molecules. The proportion of mutant mtDNA in a mixed population of normal (wild-type) and mutated mtDNA is called heteroplasmy. MtDNA mutations cause a cellular defect when the majority of mtDNA molecules are affected (i.e. high heteroplasmy level). Currently there are no effective curative treatments for diseases caused by mtDNA mutations [1]. Also, site-directed mutagenesis approaches that are routinely used to engineer the nuclear genome in many systems are only started to emerge for mammalian mtDNA [2].
Project:
Developing, optimisation and implementation of methods for de novo genetic modification the mitochondrial genome [3][4] for the correction of pathogenic mutations and for the selective elimination of pathogenic mtDNA variants in vivo in heteroplasmic models of mtDNA disease [5]. A long-term aim of the project is to use the methods to provide a site-specific means of curative manipulating mtDNA mutations [6].
General keywords: human disease, mitochondrial medicine, protein engineering
More specific keywords: mitochondrial diseases, zinc finger nucleases, genome editing, base editing
References:
1. Russell OM, Gorman GS, Lightowlers RN, Turnbull DM. Mitochondrial Diseases: Hope for the Future. Cell. 2020 Apr 2;181(1):168-188.
2. Gammage PA, Moraes CT, Minczuk M. Mitochondrial Genome Engineering: The Revolution May Not Be CRISPR-Ized. Trends Genet. 2018; 34:101-110.
3. Mok BY, de Moraes MH, Zeng J, et al. A bacterial cytidine deaminase toxin enables CRISPR-free mitochondrial base editing. Nature 2020; 583:631-637.
4. Silva-Pinheiro P, Nash PA, Van Haute L, Mutti CD, Turner K & Minczuk M. In vivo mitochondrial base editing via adeno-associated viral delivery to mouse post-mitotic tissue. Nat Commun. 2022; 13, 750
5. Gammage PA, Viscomi C, Simard M-L, et al... Minczuk M. Genome editing in mitochondria corrects a pathogenic mtDNA mutation in vivo. Nat Med 2018; 24:1691-1695.
6. Silva-Pinheiro P & Minczuk M. The potential of mitochondrial genome engineering Nat Rev Genet 2021, doi: 10.1038/s41576-021-00432-x
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