Red light slows skin cell aging in mice via fat metabolism

Researchers found that periodic red light exposure in skin cells (keratinocytes) of old mice triggers a chain of processes. A protein called SIRT4, which normally suppresses certain metabolic activities, became less active. This allowed fat oxidation and the metabolic cycle inside mitochondria, the cell’s energy-producing organelles, to become more active. The result was increased production of a molecule called acetyl-CoA.

The practical consequence was clear: more acetyl-CoA led to higher levels of a chemical modification on DNA known as H3K9 acetylation, a change in how DNA is packaged and which genes are active. The study, published in the journal eLife, showed that this altered the expression of genes linked to cell aging and reduced visible signs of cellular aging in skin tissue.

Fat metabolism as the link between light and aging

What is surprising about this research is the role of fat metabolism as an intermediary. Red light does not signal the DNA directly. It acts through a cascade: less SIRT4, more fat burning, more acetyl-CoA, and then a change in how DNA is organized. This mechanism was demonstrated in cultured skin cells and in the skin of old mice.

From mice to humans: a long road ahead

The researchers measured effects in tissue and cells, not in lifespan or clinical outcomes. Whether red light activates the same cascade in human skin, and whether that cascade would have meaningful effects on aging, has not been studied. The findings offer a starting point for further research, but caution is warranted. For those interested in longevity, the mechanism is notable: it connects mitochondrial energy metabolism directly to changes in DNA regulation in aging cells. Whether this leads to applicable interventions in humans remains an open question.

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