October 9, 2014

expert reaction to mitochondrial DNA mutations and longevity in mice

Researchers have published in the journal Scientific Reports their findings that mutations in mitochondrial DNA can reduce lifespan in mice.

Dr David Clancy, Lecturer in the Division of Biomedical and Life Sciences, Lancaster University, said:

“In this study, transgenic mice which produce high levels of mitochondrial DNA mutations were bred with normal mice to produce non-transgenic mice which were normal except that they had a significant proportion of their mitochondria which carried mutations, inherited from their transgenic mothers. These mice had lifespans reduced by about 30%. It is a good study, and follows on from a larger paper published in Nature last year.”

“The result in itself is unremarkable; what would be remarkable would be is if that level of mutation had no effect on fitness whatsoever. It is easy to shorten lifespan; lots of mutations will shorten lifespan, as will bullets and sharks, but it does not prove they cause ageing.”

“The authors do not measure the proportion of mutated mitochondria, though that is not a simple exercise to do, but the proportion will be substantial – much more than is seen in normal humans. These mutations do occur naturally but at very low levels.”

“So this work has no implications for the safety of mtDNA transfer techniques. This is not a thing that needs guarding against, because the researchers engineered mice for hypermutation.”

“However to see negative effects of mtDNA on human fitness you don’t even need mutations, as such. Naturally occurring mitochondrial genetic variation, some of which might be relatively common in the population, when combined with a poorly co-adapted set of genes on the chromosomes in the cell nucleus, will lead to reduced fitness, including lifespan (I have showed this in fruit flies – the principle is exactly the same). It is unclear the extent to which this occurs, but it is certain that it does occur.”

‘Maternally transmitted mitochondrial DNA mutations can reduce lifespan’ by Ross et al. published in Scientific Reports on Thursday 9^th October 2014.  

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/?s=mitochondrial%20dna&cat

Declared interests

None declared