Filopodia-based contact stimulated collective migration drives tissue morphogenesis

Cells migrate collectively to form tissues and organs during morphogenesis. Contact inhibition of locomotion (CIL) drives collective migration by inhibiting lamellipodial protrusions at cell-cell contacts and promoting polarization at the leading edge. Here, we report on a CIL-related collective cell behavior of myotubes that lack lamellipodial protrusions, but instead use filopodia to move as a cohesive cluster in a formin-dependent manner. Genetic, pharmacological and mechanical perturbation analyses reveal essential roles of Rac2, Cdc42 and Rho1 in myotube migration. They differentially control not only protrusion dynamics but also cell-matrix adhesion formation. Here, active Rho1 GTPase localizes at retracting free edge filopodia. Rok-dependent actomyosin contractility does not mediate a contraction of protrusions at cell-cell contacts but likely plays an important role in the constriction of supracellular actin cables. We propose that contact-dependent asymmetry of cell-matrix adhesion drives directional movement, whereas contractile actin cables contribute to the integrity of the migrating cell cluster.