Cell-autonomous control coupled with tissue context regulates the cessation of migration at the site of organ development

Organ development relies on interactions among different cell types that form three-dimensional structures to carry out specific tasks. This process often involves active migration of progenitor cells toward specific positions within the embryo, where the cells then become immotile and form stable connections among themselves and with neighboring cells. In this work, we study the process of motility loss using zebrafish primordial germ cells (PGC) as an in vivo model. We show that changes in embryonic tissues as well as cell-autonomous events regulate the behavior of germ cells as they arrive at their target region. Importantly, we find that reduction in germ cell motility is correlated with the decay of RNA encoding for Dead end 1 (Dnd1), a conserved vertebrate RNA-binding protein that is essential for PGC migration. Indeed, decreasing or increasing the level of Dnd1 results in a premature or delayed stop to motility, respectively. These findings represent an RNA decay-based mechanism for timing the duration of cell migration in vivo.