Reply to Incomplete Degeneration Versus Enhanced Regeneration in Skeletal Muscle
(2012) Journal of Biological Chemistry — Vol. 287, n° 30, p. 25550 (2012)
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- In their Letter to the Editor, Moyer and Wagner (1) propose that migration of central nuclei does not occur by day 14 post-injury in mice and that the vast majority of regenerated fibers remain centrally nucleated for over 100 days. They conclude that the faster regeneration observed in Trpc1+/+ mice would be apparent and in fact reflected a partial injury. Their assertion is based on observations obtained with dystrophic mice, in which both degeneration and regeneration persist throughout the life of the animal, and in a model of whole skeletal muscle graft. It is well known, however, that regeneration amplitude and kinetics depend on the injury method, the muscle injured, and the animal model (2). Injection of cardiotoxin is one of the most reproducible ways to induce muscle regeneration (3). Myogenic cell differentiation and new myotube formation are already observed 5–6 days post-injection. By 10 days post-injection, the overall muscle architecture is restored, although most regenerated myofibers are smaller and display central myonuclei; after 3–4 weeks, muscle is morphologically and histochemically indistinguishable from pre-injury muscle (4). In our experiments, at day 3 post-injection, muscle force production and histochemical analysis confirmed that degeneration was almost complete. By 7 days post-injection, the injured muscle presented almost 100% centrally nucleated fibers, demonstrating a fast and strong regeneration. These data thus demonstrate the validity of the cardiotoxin injury model. Our article (5) clearly shows that it is the regeneration process that is faster in Trpc1+/+ than in Trpc1−/− mice and not the degeneration that is incomplete.
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Zanou, N., & Gailly, P. (2012). Reply to Incomplete Degeneration Versus Enhanced Regeneration in Skeletal Muscle. Journal of Biological Chemistry, 287(30), 25550. https://doi.org/10.1074/jbc.L112.381012 (Original work published 2012)