title: Nervous wreck and Cdc42 cooperate to regulate endocytic actin assembly during synaptic growth.
abstract: Regulation of synaptic morphology depends on endocytosis of activated growth signal receptors, but the mechanisms regulating this membrane-trafficking event are unclear. Actin polymerization mediated by Wiskott-Aldrich syndrome protein (WASp) and the actin-related protein 2/3 complex generates forces at multiple stages of endocytosis. FCH-BIN amphiphysin RVS (F-BAR)/SH3 domain proteins play key roles in this process by coordinating membrane deformation with WASp-dependent actin polymerization. However, it is not known how other WASp ligands, such as the small GTPase Cdc42, coordinate with F-BAR/SH3 proteins to regulate actin polymerization at membranes. Nervous Wreck (Nwk) is a conserved neuronal F-BAR/SH3 protein that localizes to periactive zones at the Drosophila larval neuromuscular junction (NMJ) and is required for regulation of synaptic growth via bone morphogenic protein signaling. Here, we show that Nwk interacts with the endocytic proteins dynamin and Dap160 and functions together with Cdc42 to promote WASp-mediated actin polymerization in vitro and to regulate synaptic growth in vivo. Cdc42 function is associated with Rab11-dependent recycling endosomes, and we show that Rab11 colocalizes with Nwk at the NMJ. Together, our results suggest that synaptic growth activated by growth factor signaling is controlled at an endosomal compartment via coordinated Nwk and Cdc42-dependent actin assembly.
authors.affiliation: The Picower Institute for Learning and Memory, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. arodal@mit.edu
authors.forename: Avital A
authors.initials: AA
authors.lastname: Rodal
authors.forename: Rebecca N
authors.initials: RN
authors.lastname: Motola-Barnes
authors.forename: J Troy
authors.initials: JT
authors.lastname: Littleton
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D030801:Animals, Genetically Modified; D002417:Cattle; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004705:Endocytosis / Q000235:genetics / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009469:Neuromuscular Junction / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017729:Presynaptic Terminals / Q000502:physiology; D021381:Protein Transport / Q000235:genetics / Q000502:physiology; D013569:Synapses / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000502:physiology; D051316:Wiskott-Aldrich Syndrome Protein / Q000378:metabolism / Q000502:physiology; D020764:cdc42 GTP-Binding Protein / Q000502:physiology*
chemical_list: D000199:Actins; D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; D016212:Transforming Growth Factor beta; C477859:WASp protein, Drosophila; D051316:Wiskott-Aldrich Syndrome Protein; C089440:gbb protein, Drosophila; C483010:nwk protein, Drosophila; D020764:cdc42 GTP-Binding Protein