_{>> C2C12 Myoblast Cells <<}

C2C12 cells are myoblasts. They derive from satellite cells in the limb muscle of mice. Satellite cells are a sort of stem cells specialized to increase the muscle cell mass. The can proliferate (divide and grow) and differentiate (fuse and constitue muscle fibres). These behaviors are conserved in C2C12 cells giving the culture outstanding properties:

Left figure: C2C12 myoblasts have a proliferative state conventional in shape, size and behavior (if migration is a conventional). After stimulation by chemicals or density the cells fuse and constitute contracting muscle fibre prototypes. The surface adhesion pattern reflects the transition. Proliferative myoblasts (left) migrate by protruding and retracting furrow-like adhesions. The differentiated myotubes give up migration and start contraction (thats like migration if being pinned to the substrate). The adhesion furrows former all over the cell are now concentrated in terminal adhesion plates (right). The outmost of the myotube body floats freely in the medium. This way a 3D cell sponge is made (top animation).

Middle: During differentiation the emerging myotubes show a remarckable mobility. They migrate along the cell length axis (top animation). This orientates the actin fibres in parallel along the cell longitude (red fibres). The actin fibres are pinned to the substrate by protein complexes containing Focal Adhesion Kinase (FAK) proteins (green/yellow dots).

Right figure: The proliferating myoblast also uses f-actin and FAK to migrate over the substrate. Prior to actin fibre constitution the osmotic swelling of dynamically deposited actin meshes protrude the cell body (bright clouds in the B%W insert).

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