Lipophorin receptors regulate mushroom bodies development and participate in learning, memory, and sleep in flies

BackgroundDrosophila melanogaster Lipophorin Receptors (LpRs), LpR1 and LpR2, mediate lipid uptake. The orthologs of these receptors in vertebrates, ApoER2 and VLDL-R, bind Reelin, a glycoprotein not present in flies. These receptors are associated with the development and function of the hippocampus and cerebral cortex, important association areas in the mammalian brain. It is currently unknown whether LpRs play similar roles in the Drosophila brain. ResultsWe report that LpR-deficient flies exhibit impaired olfactory memory and sleep patterns, which seem to reflect anatomical defects found in a critical brain association area, the Mushroom Bodies (MB). Moreover, cultured MB neurons respond to mammalian Reelin by increasing the complexity of their neurites. This effect depends on LpRs and Dab, the Drosophila ortholog of the reelin signaling adaptor protein Dab1. In vitro, two of the long isoforms of LpRs allow the internalization of Reelin. ConclusionsThese findings demonstrate that LpRs contribute to MB development and function, supporting the existence of LpR-dependent signaling in Drosophila.