Mild mitochondrial stress extends lifespan in worms

Mitochondria generate ATP, the fuel that powers cells. A byproduct of this process is superoxide, a reactive oxygen molecule that can damage cellular machinery. Yet researchers have known for some time that a mild increase in mitochondrial superoxide extends lifespan across multiple model organisms. The study, published in Redox Biology, maps the signalling pathway by which this effect operates in the nematode worm Caenorhabditis elegans.

Researchers worked with worms lacking the sod-2 gene, which normally breaks down superoxide. These worms have elevated superoxide levels and live longer. Using RNA sequencing, a technique that measures which genes are switched on, the team found that genes involved in innate immunity and cuticle formation were significantly more active. This suggests mitochondria inform the cell nucleus via a signal chain, altering the cell’s maintenance behaviour.

A nerve-repair kinase as a key player

The team then searched systematically for kinases, proteins that activate other proteins, required for the extended lifespan of sod-2 worms. They identified 25 candidates. One, the kinase MAK-2, specifically affected lifespan in sod-2 worms without influencing normal worm lifespan. MAK-2 is typically associated with axon regeneration after nerve injury. Its appearance in a longevity pathway was unexpected. The researchers traced a signalling route running through SEK-3, PMK-3, MAK-2 and CEBP-1.

What does this mean for aging research?

This work was conducted in worms and does not translate directly to humans. However, mild mitochondrial stress as a lifespan-extending mechanism, known as mitohormesis, is an active area of aging research. Understanding which signalling routes enable this effect is a necessary step toward identifying potential intervention targets. That step has been taken here, though the road to any clinical application remains long.

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