Satellite cell-mediated myonuclear accretion is thought to be required for skeletal muscle fiber hypertrophy, and even drive hypertrophy by preceding growth. Recent studies in humans and rodents provide evidence that challenge this axiom. Specifically, Type 2 muscle fibers reliably demonstrate a substantial capacity to hypertrophy in the absence of myonuclear accretion, challenging the notion of a tightly regulated myonuclear domain (i.e., area that each myonucleus transcriptionally governs). In fact, a "myonuclear domain ceiling", or upper limit of transcriptional output per nucleus to support hypertrophy, has yet to be identified. Satellite cells respond to muscle damage, and also play an important role in extracellular matrix remodeling during loading-induced hypertrophy. We postulate that robust satellite cell activation and proliferation in response to mechanical loading is largely for these purposes. Future work will aim to elucidate the mechanisms by which Type 2 fibers can hypertrophy without additional myonuclei, the extent to which Type 1 fibers can grow without myonuclear accretion, and whether a true myonuclear domain ceiling exists.
|Journal||Frontiers in Physiology|
|State||Published - May 29 2018|
Bibliographical noteFunding Information:
This work was supported by National Institutes of Health grants AR071753 (to KM), AR60701 and AG049806, (to CP and JM), and AT009268 (ED-V).
© 2018 Murach, Englund, Dupont-Versteegden, McCarthy and Peterson.
- Muscle damage
- Muscle regeneration
- Type 2 fibers
ASJC Scopus subject areas
- Physiology (medical)