Mitochondrial Genome Maintenance: Damage and Repair Pathways

The mitochondrial genomic material (mtDNA), similarly to nuclear genome, is exposed to a plethora of exogenous and endogenous agents, as well as natural processes like replication that compromise the integrity and fidelity of the mtDNA, despite the abovementioned, the mtDNA does not contain genes involved in DNA repair, therefore mitochondria completely depend on the importation of nuclear-encoded elements to achieve genome maintenance, which implies a coordinated crosstalk between these two organelles. It has been determined that to counteract damage, mitochondria possess well-defined repair pathways quite similar to those of the nucleus, among which are: base excision repair (BER), mismatch repair (MMR), single-strand break repair (SSBR), microhomology-mediated end joining (MMEJ), and probably homology recombination dependent repair (HRR). If these repair pathways are nonfunctional and the lesions remain unrepaired, the emergence of mutations, deletions, and other insults may result in compromised cellular viability and disease.