TRF2 Protein Maintains Muscle Stem Cell Identity
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- TRF2 protein, long studied for protecting telomeres (chromosome ends), also preserves muscle stem cell identity and coordinates the rest-repair-renewal cycle, according to a study published in Science Advances by researchers at the University of Pennsylvania's Perelman School of Medicine.
- Foteini Mourkioti, PhD, associate professor of Orthopedic Surgery at Penn Medicine and senior author, said TRF2 levels rise and fall in a timed pattern as muscle stem cells transition through rest, tissue repair, and self-renewal.
- Mice engineered to lack TRF2 in muscle stem cells did not die but lost the molecular characteristics defining them as muscle stem cells; after injury, damaged areas filled with fat and scar tissue instead of healthy muscle.
- In a Duchenne muscular dystrophy mouse model, removing TRF2 from muscle stem cells accelerated disease progression, worsened muscle deterioration, and shortened lifespans.
- TRF2 also binds to regulatory regions across the genome containing G-quadruplexes — secondary DNA structures already under investigation as targets for cancer therapies — to preserve stem cell identity.
- The findings may illuminate a longstanding puzzle: skeletal muscle has exceptional regenerative capacity, yet cancers originating in muscle tissue are relatively uncommon, suggesting muscle stem cells use TRF2 in a distinct way.
- The research was supported by NIH grants R01 DK123356, R01s CA174904, GM101149, and FDN-143330.
Why it matters: The study pinpoints a concrete molecular mechanism — TRF2 binding at G-quadruplex DNA structures — linking muscle regeneration failure in Duchenne muscular dystrophy to loss of stem cell identity, and opens a dual research path for muscular dystrophy treatments and cancer biology in a tissue where tumors are rare.
