GETTING UNDER THE SKIN: DENDRITE-EPIDERMAL INTERACTIONS REGULATING DENDRITE MORPHOLOGY

Abstract

Dendrite morphogenesis plays a vital role in governing neuronal connectivity and function. Defects in dendrite morphogenesis have been implicated in neurological and neurodevelopmental disorders such as schizophrenia, highlighting the need to understand how dendrite morphology is regulated. Neuronal interactions with support cells are required to regulate many aspects of dendrite morphology. For example, recent studies of Drosophila dendrite arborization (da) neurons have shown that dendrite-epidermis interactions play several roles in determining dendrite morphology. In addition, the regulation of genes involved in this interaction may occur in part post-transcriptionally, through the local control of gene expression by neuronal RNA binding proteins (RBPs). Here we investigate the roles of EgfR and the neuronal RBP Found in neurons (Fne) in regulating dendrite morphogenesis in Drosophila. Our data suggest that EgfR is required in the epidermis to restrict dendrite branching in class IV da neurons, and for proper dendrite field coverage by microtubule-containing dendrites. We also find that Fne regulates various aspects of dendrite morphogenesis, including dendrite branching, enclosure in epidermal cells, and pruning. As Fne may act by down-regulating expression of cell-cell adhesion molecules, promoting cell contact with the basement membrane, and by imparting resistance to caspase-dependent pruning, we speculate that Fne regulates dendrite morphogenesis through a novel epithelial-to-mesenchymal (EMT)-like mechanism.