A fat molecule in muscles drives aging

Researchers studying both mice and humans have found that the production of cardiolipin, a fat molecule in the inner membrane of mitochondria, declines as skeletal muscle ages. The study, published in Nature Aging, shows that this falling cardiolipin level drives age-related changes in muscle fiber type and metabolism. It does so through a signal from the mitochondria to the cell nucleus: the mitochondrial membrane communicates directly with the cell’s DNA.

Mitochondria are the energy-producing organelles of cells. They are surrounded by two membranes, and cardiolipin is found in high concentrations in the inner membrane. This fat molecule is essential for the efficiency of energy production. As the body ages, cardiolipin synthesis declines, with consequences for how muscle cells function. The researchers show that this triggers a cascade through a receptor called ERR-gamma (a protein that regulates gene activity), ultimately altering the composition of muscle fibers toward a less efficient type.

From fiber type to aging

There are broadly two types of muscle fibers: fast fibers for strength and power, and slow fibers for endurance. With aging, the balance shifts in ways that contribute to muscle weakness and slower metabolism. The new finding suggests cardiolipin plays a key role in that shift, at least in mice and in cell experiments using human muscle tissue.

Potential targets for intervention

The study offers potentially interesting angles for preserving muscle function in later life. If cardiolipin synthesis can be maintained, it may be possible to slow age-related muscle decline. Whether this can be achieved pharmacologically or through lifestyle changes remains unknown. The results are promising, but confirmation in large clinical trials in humans is still lacking.

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