A re-evaluation of DNA repair during skeletal myogenesis in vitro

In previous studies on DNA repair during myogenesis, comparisons made of repair in post-replication myoblasts and in myotubes led to the conclusion that the capacity to repair damage in DNA decreased during myoblast differentiation. Using unscheduled DNA synthesis in response to UV-induced damage as an indicator of DNA repair in a myogenic line of rat skeletal muscle, it is demonstrated that nuclei in myotubes possess identical repair capacity as that in proliferating myoblasts. Furthermore, a brief increase in DNA repair capacity was observed to immediately follow the cessation of replicative DNA synthesis. This transient increase in repair capacity is consistent with the data of earlier reports and explains the previous but inappropriate conclusion that repair diminishes during myogenic differentiation. This transient increase in the capacity to repair DNA was not observed in a developmentally defective, non-differentiating line of similar myogenic origin.