Are mtDNA mutations important in human ageing?
In humans, the increase in mtDNA mutations with age does not prove that they have a role in the ageing process; they could just be biological markers of accumulating damage. It has been reported that mitochondria isolated from the fibroblasts of old animals that was subsequently microinjected into young cells can lead to cellular degeneration, similar results were also achieved from young, partially uncoupled mitochondria (21,22). Although the nature of the mtDNA abnormalities was not investigated in these studies, these results demonstrate that altered mitochondria may be playing a crucial role in the decline in cellular function. However, a recent study has shown that somatic mutation accumulation with age is dependent on nuclear genetic background in mice and not associated with increase in ROS or senescence (23). This suggests that the accumulation of the mtDNA mutations may not be as straightforward as first thought and that an individual’s nuclear background may affect their susc
