Optogenetic approach for targeted activation of global calcium transients in differentiated C2C12 myotubes

Area of Science:

• Muscle physiology
• Cellular biology
• Neuroscience

Background:

• Excitation-contraction coupling is crucial for muscle function, initiated by localized membrane depolarization at the neuromuscular junction.
• Existing methods for studying this process lack the spatiotemporal precision of natural neuromuscular junction depolarization.
• Understanding this coupling is vital for muscle research and disease modeling.

Purpose of the Study:

• To develop a novel optogenetic technique to precisely control and study membrane depolarization in muscle cells.
• To investigate the resultant calcium dynamics and muscle cell response with high spatiotemporal resolution.
• To provide a contactless and efficient method for analyzing excitation-calcium coupling.

Main Methods:

• Utilized optogenetics to induce targeted membrane depolarization in C2C12 muscle cells via photostimulation.
• Employed confocal calcium imaging to monitor cellular calcium responses.
• Applied photostimulation with spatial dimensions comparable to the neuromuscular junction.

Main Results:

• Successfully generated global cellular calcium responses following photostimulation-induced membrane depolarization.
• Demonstrated that the observed calcium response is a result of propagated membrane depolarization.
• Validated the technique's ability to mimic physiological depolarization with high precision.

Conclusions:

• The developed optogenetic technique offers a powerful, contactless tool for studying muscle excitation-contraction coupling.
• This method provides unprecedented spatiotemporal control over membrane depolarization, enabling detailed analysis of calcium dynamics.
• It facilitates research into calcium increase/release and decrease/re-uptake mechanisms triggered by propagated depolarization.