Non-autonomous role of Cdc42 in cell-cell communication during collective migration.

Collective cell migration is involved in numerous processes both physiological, such as embryonic development, and pathological such as metastasis. Compared to single cell migration, collective motion requires cell behaviour coordination through an as-yet poorly understood but critical cell-cell communication mechanism. Using Drosophila border cell migration, we show here that the small Rho GTPase Cdc42 regulates cell-cell communication. Indeed, we demonstrate that Cdc42 controls protrusion formation in a cell non-autonomous manner. Moreover, we found that the endocytic small GTPase Rab11, controls Cdc42 localisation to the periphery of migrating border cell clusters. Accordingly, over-expression of Cdc42 in border cells rescues the loss of Rab11 function. In addition, we showed that Cdc42 acts upstream of Moesin, a cytoskeletal regulator known to function downstream of rab11. Thus, our study positions Cdc42 as a new key player in cell-cell communication, acting downstream of Rab11.