Mechanical strain altered IGF-I gene splicing in C2C12 cells, with a single ramp stretch upregulating both IGF-IEa and MGF, whereas cyclical stretch reduced IGF-IEa but upregulated MGF.
Does mechanical strain influence IGF-I gene splicing in developing muscle cells?
Mechanical strain differentially regulates the splicing of the IGF-I gene into IGF-IEa and MGF in developing skeletal muscle cells.
It has been shown that the insulin-like growth factor (IGF-I) gene is spliced in response to mechanical signals producing forms of IGF-I which have different actions. In order to study how mechanical signals influence this gene splicing in developing muscle, C2C12 cells were grown in three-dimensional (3D) culture and subjected to different regimens of mechanical strain. IGF-IEa which initiates the fusion of myoblasts to form myotubes was found to be constitutively expressed in myoblasts and myotubes (held under endogenous tension) and its expression upregulated by a single ramp stretch of 1-h duration but reduced by repeated cyclical stretch. In contrast, mechano growth factor (MGF), which is involved in the proliferation of mononucleated myoblasts that are required for secondary myotube formation and to establish the muscle satellite (stem) cell pool, showed no significant constitutive expression in static cultures, but was upregulated by a single ramp stretch and by cycling loading. The latter types of force simulate those generated in myoblasts by the first contractions of myotubes. These data indicate the importance of seeking to understand the physiological signals that determine the ratios of splice variants of some growth factor/tissue factor genes in the early stages of development of skeletal muscle.
Cheema et al. (Mon,) conducted a other in Skeletal muscle development. Mechanical strain (single ramp stretch or repeated cyclical stretch) vs. Static cultures was evaluated on Expression of IGF-IEa and MGF splice variants. Mechanical strain altered IGF-I gene splicing in C2C12 cells, with a single ramp stretch upregulating both IGF-IEa and MGF, whereas cyclical stretch reduced IGF-IEa but upregulated MGF.