Dynamic expression and localization of the LIN-2/7/10 protein scaffolding complex duringC. elegansvulval development

The evolutionarily conserved LIN-2 (CASK)/LIN-7 (Lin7A-C)/LIN-10 (APBA1) complex plays an important role in regulating spatial organization of membrane proteins and signaling components. In C. elegans, the complex is essential for development of the vulva by promoting the localization of the sole Epidermal Growth Factor Receptor (EGFR) orthologue, LET-23, to the basolateral membrane of the vulva precursor cells (VPCs) where it can specify the vulval cell fate. However, the expression and localization of the LIN-2/7/10 complex, and how the complex regulates receptor localization, are not known. Here we describe an in vivo analysis of the complex in C. elegans VPCs. Only LIN-7 colocalizes with LET-23 EGFR at the basolateral membrane, while the LIN-2/7/10 complex components instead colocalize at cytoplasmic foci, consistent with Golgi or endosomes. LIN-10 recruits LIN-2, which in turn recruits LIN-7. We demonstrate that the complex forms in vivo with particularly strong interaction and colocalization between LIN-2 and LIN-7. Our data suggest that the LIN-2/7/10 complex forms on endomembrane compartments where it likely targets LET-23 EGFR to the basolateral membrane, and point to distinct regulation between LIN-2/7 and LIN-10. Summary Statement LIN-10 recruits LIN-2 and LIN-7 to Golgi or recycling endosomes, consistent with targeting rather than tethering the epidermal growth factor receptor to the basolateral membrane in C. elegans .