Publication types Comparative Study Research Support, Non-U.S. We propose that an eIF3-eIF4A-dependent alternative initiation pathway bypasses 4E-BP to ensure adequate translation of ecdysone-induced genes.ĤE-BP 5′ UTR Mical dendrite eIF3 eIF4A ecdysone pruning.Ĭopyright © 2018 The Author(s). The dendritic arborization (da) neurons of the peripheral sensory system in Drosophila larvae are a model system used to study dendritic arborization. Further, Drosophila da sensory neurons appear to exhibit at least three different types of class-specific dendrite-dendrite interactions: persistent repulsion by all branches, repulsion only by terminal dendrites, and no repulsion. Dendrites allow neurons to integrate sensory or synaptic inputs, and the spatial disposition and local density of branches within the dendritic arbor limit the number and type of inputs1,2. Functional analyses indicate that eIF4A regulates eIF3-mRNA interactions in a helicase-dependent manner. eIF4A and eIF3 are stringently required for translation of the ecdysone target Mical, and this depends on the 5' UTR of Mical mRNA. We found that the canonical cap-binding complex eIF4F is dispensable for dendrite pruning, but the eIF3 complex and the helicase eIF4A are required, indicating that differential translation initiation mechanisms are operating during dendrite pruning. To uncover how efficient translation of ecdysone targets is achieved under these conditions, we assessed the requirements for translation initiation factors during dendrite pruning. In addition, ecdysone activates the eukaryotic initiation factor 4E-binding protein (4E-BP) to inhibit cap-dependent translation initiation. These data together suggest that dendritic territories of adult v'ada neurons are specified by two distinct mechanisms: Ventral boundaries are specified independently of dendritic contacts, whereas the lateral boundaries are established through repulsive interactions between homotypic dendrites. Dendrite pruning of Drosophila sensory neurons during metamorphosis is induced by the steroid hormone ecdysone through a transcriptional program. Obtaining neuron transcriptomes is challenging their complex morphology and interconnected microenvironments make it difficult to isolate neurons without potentially altering gene expression.
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