Muscle stem cell growth mechanism found

LA JOLLA, Calif., Dec. 11 (UPI) -- A U.S. study has identified the mechanism by which adult muscle stem cells shift from dormancy to actively building new tissue.

During muscle regeneration, a natural response to injury and disease, environmental cues cause adult muscle stem cells to start creating muscle tissue, researchers said. Although the signaling pathways controlling muscle regeneration are fairly well known, how the signals lead to altered chromatin structure hasn't been clear.

In the new study, scientists at the Burnham Institute for Medical Research analyzed the mechanism by which certain cellular signaling cues cause epigenetic modifications when released within the regenerative microenvironment, thus controlling the expression of genes regulating growth and differentiation of muscle stem cells that repair injured muscle.

The researchers, led by Dr. Pier Lorenzo Puri, showed how two signaling pathways work together to assemble components of the protein complexes responsible for muscle-specific transcription and how each pathway is responsible for a distinct step in the transcription process.

Additionally, the team was able to pharmacologically separate the two steps, showing selective interference with either cascade leads to incomplete assembly of protein complexes, thus preventing muscle-specific gene expression.

The findings were reported in the journal Molecular Cell.