Respective roles of the DRL receptor and its ligand WNT5 in Drosophila mushroom body development.

International audienceIn recent decades, Drosophilamushroom bodies (MBs) have become a powerful model for elucidating the molecular mechanismsunderlying brain development and function. We have previously characterized the derailed(drl; also known as linotte) receptortyrosine kinase as an essential component of adult MB development. Here we show, using MARCM clones, a non-cell-autonomousrequirement for the DRL receptor in MB development. This result is in accordance with the pattern of DRL expression, which occursthroughout development close to, but not inside, MB cells. While DRL expression can be detected within both interhemispheric glialand commissural neuronal cells, rescue of the drlMB defects appears to involve the latter cellular type. The WNT5 protein has beenshown to act as a repulsive ligand for the DRL receptor in the embryonic central nervous system. We show here that WNT5 isrequired intrinsically within MB neurons for proper MB axonal growth and probably interacts with the extrinsic DRL receptor inorder to stop axonal growth. We therefore propose that the neuronal requirement for both proteins defines an interactingnetwork acting during MB development