Unravelling SAC Dependent Behaviour In C2C12 Myoblasts During Myogenesis With Stretching Conditions
Elsa Thomasson, Janos Vörös, Alfredo Franco-Obregón
Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zurich
Today there is a big interest in muscle related disorders such as sarcopenia
myoblasts under cyclic stretch maintains them proliferative whereas ramp
and muscular dystrophy. In order to combat these diseases new therapies
stretch biases their development towards differentiation. It has been
and technologies to enhance muscle regeneration have to be developed
suggested that calcium dependent signaling pathways may regulate cell
based on a better understanding of muscle development, myogenesis.
fusion but the mechanisms controlling the transmembrane calcium fluxes
Activated myoblasts first undergo many rounds of cell division. Depending
that render myoplasmic calcium homeostasis remain unclear. The aim of
on the biochemical and mechanical environment, myoblasts may next
this work is to investigate whether mechanically regulated calcium influx is
withdraw from the cell cycle in preparation for biochemical differentiation,
an upstream initiator of the biochemical signaling pathway leading to
culminating with fusion to form multinucleated myotubes. Placing
myogenic or non-myogenic gene expression. Materials and Methods
C2C12 myoblasts were put under 2D uniaxial cyclic stretch
(STREX-ST-140-10 from B-Bridge International) in presence of streptomycin, a stretch activated calcium channel (SAC) blocker or nifedipine, a voltage gated L-type calcium channel blocker. The stretching times were varied and the expression of the two isoforms of Insulin-like Growth Factor 1 (IGF-1) namely IGF-1Ea and Mechano Growth Factor (MGF) were analyzed with real-time PCR. IGF-1Ea and MGF have earlier been shown to have oppsite effects where MGF maintains the cells proliferative while IGF-1Ea pushes them towardsthe differentation pathway. Control - MGF Control - MGF Nifed - MGF Strept - MGF ontro 400 stati 300 tatio 100 antitatio Stretching time (Minutes) Stretching time (Minutes) Control - IGF-1Ea Control - IGF-1Ea Nifed - IGF-1Ea Strept - IGF-1Ea static co ative 200 tion rela uantitati Stretching time (Minutes) Stretching time (Minutes) Conclusions and Discussion Acknowledgements
• Stretch increases the MGF expression and hence the proliferative state is favoured. • Stretch increases IGF-1Ea expression but not to the same extent as MGF indicating that cyclic stretch
ETH Zurich is acknowledged for funding.
• The stretch effect is rescued in samples treated with streptomycin showing that stretch induced
upregulation of MGF is mediated via calcium influx through stretch activated calcium channels (SACs).
• Nifedipine has a similar rescuing effect which strengthens the conclusion that the stretch effect is calcium dependent.
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