By Gemma Conroy
The cellular batteries known as mitochondria sometimes dump DNA into their surroundings, which can contribute to inflammation during ageing. Now a study in mice reveals why this dumping occurs: mitochondria are expelling ‘tainted’ DNA1.
Scientists found that, in the cells of ageing mice with kidney inflammation, strands of mitochondrial DNA (mtDNA) contained an excess of certain types of nucleotides — molecular building blocks — that can harm DNA. This excess prompted the mitochondria to eject the abnormal fragments of genetic code into the cytosol, a fluid that fills the cell, in which the free-roaming mtDNA kick-started key inflammatory pathways associated with ageing.
The study is exciting because it helps to explain why and how mitochondria throw away their DNA, says Timothy Shutt, a medical geneticist at the University of Calgary in Canada, who focuses on mitochondria. This insight could help researchers to better understand mitochondria’s contribution to inflammageing — the chronic inflammation that occurs as people get older, adds Shutt.
The findings were published 24 September in Nature.
