Prof Jocelyn McDonald

Throughout embryonic development, and in cancer, cells often move in groups to form, shape and remodel tissues and organs. Such "collectively" migrating cells adhere strongly to one another but also coordinate their movement so that they can move as a single unit. The question of how, when and why cells migrate collectively, rather than as single cells, is still poorly understood. Drosophila border cells are an excellent genetic model that have led to fundamental discoveries of conserved regulatory pathways that underlie collective cell migration. Border cells require finely-tuned regulation of the cytoskeleton and cell adhesion to keep cells connected and moving efficiently through a complex tissue environment. We recently found that Protein Phosphatase 1 (Pp1) is required for border cell migration. Loss of Pp1 causes border cells to round up, dissociate from the cluster, and migrate as single cells with altered motility. We further show that Pp1 activity, through specific phosphatase complexes, promotes cohesive border cell migration by restricting actomyosin contractility to the periphery of the collective and maintaining proper cadherin-catenin complex protein levels at cell-cell junctions. Given the high conservation of Pp1 complexes, our study identifies Pp1 as a major regulator of collective versus single cell migration.