Integrin α3 subunit participates in myoblast adhesion and fusion in vitro

Satellite cells are myogenic precursor cells, participating in growth, and regeneration of skeletal muscles. The proteins that play a role in myogenesis are integrins. In this report, we show that the integrin α3 subunit is expressed in quiescent satellite cells and activated myoblasts. We also find that in myoblasts the integrin α3 subunit is localized at cell–cell and cell–extracellular matrix contacts. We notice that increase in protein and mRNA encoding the integrin α3 subunit accompanies myoblast differentiation. Using double immunofluorescence and immunoprecipitation experiments, we demonstrate that the integrin α3 subunit co-localizes with actin, and binds the integrin β1 subunit and ADAM12, suggesting that the complex α3β1/ADAM12 is probably involved in myoblast fusion. Importantly, overexpression of the full-length integrin α3 subunit increases myoblast fusion whereas an antibody against its extracellular domain inhibits fusion. These data demonstrate that the integrin α3 subunit may contribute to satellite cell activation and then myoblast adhesion and fusion.