Plekhh1, a partner of myosin 1 and an effector of EphB2, controls the cortical actin network during cell repulsion.

EphB2-ephrinB signalling, which plays a major role in cell segregation during embryonic development and tissue homeostasis, induces an important reorganization of the cortical actin network. We have previously reported that myosin 1b contributes to reorganization of the cortical actin network upon EphB2 signalling. In this report, we identify Plekhh1 as a new partner of members of the myosin 1 family and EphB2 receptors. Plekhh1 interacts with myosin 1b via its N-terminal domain and with EphB2 via its C-terminal domain. Furthermore, Plekhh1 is tyrosine phosphorylated, and this depends on EphB2 kinase activity. Similar to the effects of manipulating levels of myosin 1b and myosin 1c, manipulation of Plekhh1 expression levels alters the formation of filopodia, the length of focal adhesions and the formation of blebs. Furthermore, binding of the Plekhh1 interacting domain to myosin 1b increases the motor activity of myosin 1b in vitro. Taken together, our data show that Plekhh1 is an effector of EphB2 and suggest that Plekhh1 regulates the cortical actin network via the interaction of its N-terminal domain with myosin 1 upon EphB2-ephrinB signalling.