title: Imp promotes axonal remodeling by regulating profilin mRNA during brain development.
abstract: Neuronal remodeling is essential for the refinement of neuronal circuits in response to developmental cues [1-4]. Although this process involves pruning or retraction of axonal projections followed by axonal regrowth and branching, how these steps are controlled is poorly understood. Drosophila mushroom body (MB) γ neurons provide a paradigm for the study of neuronal remodeling, as their larval axonal branches are pruned during metamorphosis and re-extend to form adult-specific branches [5]. Here, we identify the RNA binding protein Imp as a key regulator of axonal remodeling. Imp is the sole fly member of a conserved family of proteins that bind target mRNAs to promote their subcellular targeting [6-12]. We show that whereas Imp is dispensable for the initial growth of MB γ neuron axons, it is required for the regrowth and ramification of axonal branches that have undergone pruning. Furthermore, Imp is actively transported to axons undergoing developmental remodeling. Finally, we demonstrate that profilin mRNA is a direct and functional target of Imp that localizes to axons and controls axonal regrowth. Our study reveals that mRNA localization machineries are actively recruited to axons upon remodeling and suggests a role of mRNA transport in developmentally programmed rewiring of neuronal circuits during brain maturation.
authors.affiliation: Institute of Biology Valrose, CNRS-UMR7277/INSERM-UMR1091, University of Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Medioni
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Mirana
authors.initials: M
authors.lastname: Ramialison
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Ephrussi
authors.affiliation: Institute of Biology Valrose, CNRS-UMR7277/INSERM-UMR1091, University of Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France; European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany. Electronic address: besse@unice.fr.
authors.forename: Florence
authors.initials: F
authors.lastname: Besse
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D024521:Mushroom Bodies / Q000502:physiology; D016501:Neurites / Q000378:metabolism; D009474:Neurons / Q000502:physiology; D051304:Profilins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; C498778:Imp protein, Drosophila; D051304:Profilins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C495737:chic protein, Drosophila