Abstract
Dendritic arbor morphology influences how neurons receive and integrate extracellular signals. We show that the ELAV/Hu family RNA-binding protein Found in neurons (Fne) is required for space-filling dendrite growth to generate highly branched arbors of Drosophila larval class IV dendritic arborization neurons. Dendrites of fne mutant neurons are shorter and more dynamic than in wild-type, leading to decreased arbor coverage. These defects result from both a decrease in stable microtubules and loss of dendrite-substrate interactions within the arbor. Identification of transcripts encoding cytoskeletal regulators and cell-cell and cell-ECM interacting proteins as Fne targets using TRIBE further supports these results. Analysis of one target, encoding the cell adhesion protein Basigin, indicates that the cytoskeletal defects contributing to branch instability in fne mutant neurons are due in part to decreased Basigin expression. The ability of Fne to coordinately regulate the cytoskeleton and dendrite-substrate interactions in neurons may shed light on the behavior of cancer cells ectopically expressing ELAV/Hu proteins.
Highlights
Neurons display a diversity of dendrite morphologies that are tailored to their particular synaptic or sensory functions
We show that the ELAV/Hu family RNA-binding protein Found in neurons (Fne) is required for space-filling dendrite growth to generate highly branched arbors of Drosophila larval class IV dendritic arborization neurons
Wild-type neurons continued to arborize during L2, leading to an increase in field coverage as development progressed. fne− neurons still showed an excess of terminal branches at this time point (1.8-fold, p
Summary
Neurons display a diversity of dendrite morphologies that are tailored to their particular synaptic or sensory functions. The Drosophila larval dendritic arborization (da) neurons are a well-established model system for studying dendrite patterning. These sensory neurons comprise four morphologically and functionally distinct classes with overlapping territories along the larval body wall [4]. Class IV da neurons elaborate highly branched, two-dimensional dendritic arbors between the epidermis and the underlying extracellular matrix (ECM) that completely and non-redundantly tile the larval body wall [4,6,7]. The uniform, space-filling morphology of these arbors is the result of a highly dynamic growth and refinement process as well as repulsive interactions between neighboring dendrites [1,2]. As larval growth reaches its endpoint, dendritic branches must stabilize to maintain proper innervation of the epidermis [9]
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