A fat-building pathway declined in mouse muscle stem cells with age
A chemically tagged form of citrate made through this pathway was about 80% lower in old mouse muscle stem cells than in young cells.
Limit: Pathway activity in intact muscle was not measured
Edited by Boris Djordjevic · AgingResearch.News
In experiments in male C57/BL6J mice and their muscle stem cells, researchers compared animals aged 6–8 months with those aged 24–26 months. They studied cells grown in the lab and muscle regeneration after injury in mice. They traced glutamine, an amino acid, through a metabolic pathway that supplies material for making fatty acids.
Older cells had less glutaminase, an enzyme that processes glutamine. They also sent less glutamine through the pathway’s reverse-running route. A chemically tagged form of citrate, a molecule made by that route, was about 80% lower in old than young cells. Increasing glutaminase in older cells increased a measure of cell division in the lab. The authors concluded that this route supports the fatty acid stores needed for muscle stem cell function.
Why it matters
Age-related declines in muscle regeneration contribute to loss of independence. Understanding how stem cells obtain materials for growth may help clarify why their function falters with age.
Caveats
The metabolic tracing and cell-division results came from cells grown in the lab, not measurements of muscle strength. The age comparisons used male mice and do not establish effects in females or people.
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