Cytosolic mtDNA and associated EYA-mediated pro-inflammatory signaling modulate healthspan in Drosophila.

Mitochondrial dysfunction and pro-inflammatory signaling are each key drivers of aging. However, a clear understanding of the connections between mitochondrial homeostasis, inflammation and lifespan determination remains elusive. Upon mitochondrial stress or damage, mtDNA can be released into the cytosol thus encountering cytosolic DNA sensors and activating pro-inflammatory responses. Here, we report a striking age-related increase in cytosolic mtDNA, which can be counteracted by mitophagy, in Drosophila brain and muscle tissue. We find that upregulation of DNase II, an acid DNase which digests DNA in the autophagy-lysosome system, reduces cytosolic mtDNA levels in aged flies and prolongs healthspan. Reducing the abundance of cytosolic DNA in aged flies also dampens Rel/NF-κB pro-inflammatory signaling. Furthermore, we show that inhibition of EYA, a Rel/NF-κB-binding protein involved in immune sensing of DNA, in aging neurons counteracts brain aging and prolongs healthspan. Our findings identify DNase II and EYA as therapeutic targets to prolong healthspan.