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Updated: Jul 15, 2026
Isolation of Human Myoblasts, Assessment of Myogenic Differentiation, and Store-operated Calcium Entry Measurement
Published on: July 26, 2017
Endoplasmic reticulum stress increases myofiber formation in vitro
Keiko Nakanishi1, Naoshi Dohmae, Nobuhiro Morishima
1The Biomolecular Characterization Team, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Abstract:
Myoblast differentiation involves myoblast fusion followed by myofiber formation. We recently demonstrated that endoplasmic reticulum (ER) stress signaling occurs during myoblast differentiation in vivo. This signaling results in apoptosis in a subpopulation of myoblasts. In a cell culture model of myogenesis, inhibition of ER stress signaling blocked apoptosis and myoblast differentiation. To further examine the role of ER stress during myogenesis, we exposed cultured myoblasts to ER stress inducers during the transition from proliferation to differentiation. The stress inducers tunicamycin (an inhibitor of N-glycosylation in the ER) and thapsigargin (an inhibitor of ER-specific calcium ATPase) were used at doses that induce 40-50% apoptosis in myoblast cultures. Increased ER stress enhanced differentiation-associated apoptosis of myoblasts. It is likely that apoptosis induced by ER stress selectively eliminates vulnerable cells. We found that the surviving myoblast cells were even more resistant to apoptosis. Remarkably, the surviving cells efficiently differentiated into contracting myofibers that are rarely found in culture models of myogenesis. Our observations suggest that ER stress exerts a positive effect on myofiber formation, possibly mimicking the action of signals that drive apoptosis and differentiation in vivo. These results may provide important insight for developing therapies to improve myofiber formation.
Insights
Endoplasmic reticulum (ER) stress enhances muscle cell (myoblast) differentiation by selectively eliminating vulnerable cells. Surviving myoblasts form robust myofibers, suggesting ER stress aids muscle repair therapies.
Area of Science:
- Cell Biology
- Muscle Physiology
- Biochemistry
Background:
- Myoblast differentiation is crucial for muscle repair and involves fusion and myofiber formation.
- Endoplasmic reticulum (ER) stress signaling has been observed during myogenesis in vivo.
- ER stress inhibition in cell culture blocked apoptosis and myoblast differentiation.
Purpose of the Study:
- To investigate the role of ER stress inducers during myoblast differentiation.
- To determine the effect of ER stress on apoptosis and myofiber formation in myoblasts.
- To explore the potential therapeutic implications of ER stress in muscle regeneration.
Main Methods:
- Cultured myoblasts were exposed to ER stress inducers (tunicamycin, thapsigargin) during the proliferation-to-differentiation transition.
- Doses were chosen to induce 40-50% apoptosis in myoblast cultures.
- Apoptosis rates, cell survival, and myofiber formation were assessed.
Main Results:
- Increased ER stress significantly enhanced differentiation-associated apoptosis in myoblasts.
- Surviving myoblasts exhibited increased resistance to apoptosis.
- These surviving cells efficiently differentiated into contracting myofibers, a rare outcome in standard culture models.
Conclusions:
- ER stress selectively eliminates vulnerable myoblasts, promoting the survival and differentiation of more resistant cells.
- ER stress positively influences myofiber formation, potentially mimicking in vivo signaling pathways.
- These findings offer insights for developing therapies to enhance muscle regeneration and myofiber formation.
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