Identification of PKN2 and MOB4 as Coordinators of Collective Cell Migration

In animals, collective cell migration is critical during development and adult life for repairing organs. It remains, however, poorly understood compared with single cell migration. Polymerization of branched actin by the RAC1-WAVE-Arp2/3 pathway is well established to power membrane protrusions at the front of migrating cells, but also to maintain cell junctions in epithelial monolayers. Here we performed a screen for novel regulators of collective cell migration by identifying genes associated with the RAC1-WAVE-Arp2/3 pathway at cell junctions using dependency maps and by inactivating these candidates using CRISPR/Cas9. In wound healing, MCF10A epithelial cells collectively migrate towards the free space in a coordinated manner. PKN2 knockout (KO) cells display decreased collective migration due to destabilization of adherens junctions, whereas MOB4 KO cells display increased collective migration with a swirling behavior. Upon wound healing, PKN2 relocalizes to lateral junctions and maintains coordinated migration in the monolayer, whereas MOB4 relocalizes to the front edge of cells migrating towards the wound. The role of MOB4 in controlling collective migration requires YAP1, since MOB4 KO cells fail to activate YAP1 and their phenotype is rescued by constitutively active YAP1. Together, our data reveal two complementary activities required for coordinating cells in collective migration.