Caenorhabditis elegansSEL-5/AAK1 regulates cell migration and cell outgrowth independently of its kinase activity

Abstract

During Caenorhabditis elegans development multiple cells migrate long distances or extend processes to reach their final position and/or attain proper shape. Wnt signalling pathway stands out as one of the major coordinators of cell migration or cell outgrowth along the anterior-posterior body axis. Wnt signalling outcome is fine-tuned by various mechanisms including endocytosis. In this study we show that SEL-5, the C. elegans orthologue of mammalian AP2-associated kinase AAK1, acts together with the retromer complex as a positive regulator of EGL-20/Wnt signalling during the migration of QL neuroblast daughter cells. At the same time, SEL-5 in cooperation with the retromer complex is also required during excretory canal cell outgrowth in a Wnt-independent manner. Importantly, SEL-5 kinase activity is not required for its role in either neuronal migration or excretory cell outgrowth and neither of these processes is dependent on DPY-23/AP2M1 phosphorylation. While Wnt proteins do not significantly contribute to the excretory canal guidance, LIN-44/Wnt and LIN-17/Frizzled together generate a stop signal inhibiting further canal outgrowth.