FIGURE 2.

The mitochondrial response to unrepaired DNA damages. Unrepaired mtDNA damages can be accumulated and lead to the mitochondrial dysfunction. To maintain its function, the mitochondria have developed several quality control events. TLS is an mtDNA damage tolerance pathway to bypass the mtDNA replication block. Mitochondrial fusion provides mtDNA complementation by mixing damaged and normal mtDNA. Mitochondrial fission segregates the part of a mitochondrion with damaged mtDNA and maintains the integrity of the healthy part of a mitochondrion. Mitochondria with excessive damaged mtDNA are selectively degraded through mitophagy. The interaction between the mitophagy and the mitochondrial fission/fusion has also been reported.