title: Regulation of patterned dynamics of local exocytosis in growth cones by netrin-1.
abstract: Axonal guidance and synaptic specification depends on specific signaling mechanisms that occur in growth cones. While several signaling pathways implicated in cone navigation have been identified, membrane dynamics in growth cones remains largely unknown. We took advantage of SynaptopHluorin and high-speed optical recordings to monitor the patterns of membrane dynamics in rat hippocampal growth cones. We show that exocytosis occurs both at the peripheral and central domains, including filopodia, and that SynaptopHluorin signals occur as spontaneous patterned peaks. Such transients average approximately two per minute and last ∼30 s. We also demonstrate that the chemoattractant Netrin-1 elicits increases in the frequency and slopes of these transients, with peaks averaging up to six per minute in the peripheral domain. Netrin-1-dependent regulation of exocytotic events requires the activation of the Erk1/2 and SFK pathways. Furthermore, we show that domains with high SynaptopHluorin signals correlate with high local calcium concentrations and that local, spontaneous calcium increases are associated with higher SynaptopHluorin signals. These findings demonstrate highly stereotyped, spontaneous transients of local exocytosis in growth cones and that these transients are positively regulated by chemoattractant molecules such as Netrin-1.
authors.affiliation: Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid 28031, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Ros
authors.affiliation: Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid 28031, Spain.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cotrufo
authors.affiliation: Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid 28031, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Martínez-Mármol
authors.affiliation: Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid 28031, Spain, Vall d'Hebron Institute of Research, Barcelona 08035, Spain, and Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain esoriano@ub.edu.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Soriano
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology; D002478:Cells, Cultured; D005089:Exocytosis / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020439:Growth Cones / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D009414:Nerve Growth Factors / Q000502:physiology*; D000075388:Netrin-1; D009474:Neurons / Q000502:physiology; D061848:Optical Imaging; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000502:physiology*
chemical_list: D009414:Nerve Growth Factors; C000617354:Ntn1 protein, rat; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; C514578:synaptopHIuorin; D049452:Green Fluorescent Proteins; D000075388:Netrin-1
keywords: Netrin-1; SynaptopHluorin; exocytosis; growth cone
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