Key result
Stretching by 2% elongation at 0.25 Hz for 12 hours was the most effective protocol in up-regulating myogenic/anabolic factors and down-regulating pro-apoptotic and atrophy genes in myotubes.
Why the study?
Mechanical loading of differentiated myoblasts in vitro may mimic skeletal muscle loading in vivo, but the conditions producing the most effective muscle cell biological responses were uncharacterized.
Does mechanical loading (stretching) improve myogenic/anabolic factor expression and reduce pro-apoptotic/atrophy genes in skeletal myotubes?
Does mechanical loading (stretching) improve myogenic/anabolic factor expression and reduce pro-apoptotic/atrophy genes in skeletal myotubes?
A low strain, low frequency intermediate duration stretching protocol (2% elongation at 0.25 Hz for 12 h) optimally up-regulates myogenic/anabolic factors and down-regulates pro-apoptotic and atrophy genes in C2C12 myotubes in vitro.
In vitro optimization of stretching warrants in vivo validation; leaves open translation to clinical muscle preservation.
BACKGROUND/AIM: Mechanical loading of differentiated myoblasts in vitro may mimic loading patterns of skeletal muscle in vivo. However, it is still uncharacterized the loading conditions that can produce the most effective muscle cells' biological responses, in vitro. This study investigated the effects of different loading protocols on the expression of myogenic regulatory factors, anabolic, atrophy and pro-apoptotic factors in skeletal myotubes. MATERIALS AND METHODS: C2C12 myoblasts were differentiated and underwent various stretching protocols by altering their elongation, frequency and duration, utilizing an in vitro cell tension system. The loading-induced expression changes of MyoD, Myogenin, MRF4, IGF-1 isoforms, Murf1, Atrogin, Myostatin, Foxo and Fuca were measured by Real Time-PCR. RESULTS: Stretching by 2% elongation at 0.25 Hz for 12 h was overall the most effective in inducing beneficial responses. CONCLUSION: A low strain, low frequency intermediate duration stretching can most effectively up-regulate myogenic/anabolic factors and down-regulate pro-apoptotic and atrophy genes in myotubes.
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Moustogiannis et al. (2020) studied this question. Mechanical loading (stretching protocols) was evaluated on Expression changes of MyoD, Myogenin, MRF4, IGF-1 isoforms, Murf1, Atrogin, Myostatin, Foxo and Fuca. Stretching by 2% elongation at 0.25 Hz for 12 hours was the most effective protocol in up-regulating myogenic/anabolic factors and down-regulating pro-apoptotic and atrophy genes in myotubes.
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