The Journal of Neuroscience, August 13, 2008, 28(33):8316-8325; doi:10.1523/JNEUROSCI.2304-08.2008
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Cellular/Molecular
Nervous Wreck and Cdc42 Cooperate to Regulate Endocytic Actin Assembly during Synaptic Growth
Avital A. Rodal,
Rebecca N. Motola-Barnes, and
J. Troy Littleton
The Picower Institute for Learning and Memory, and Departments of Biology and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
Correspondence should be addressed to Avital A. Rodal, The Picower Institute for Learning and Memory, Departments of Biology and Brain and Cognitive Sciences, Massachusetts Institute of Technology, 46-3251, 43 Vassar Street, Cambridge, MA 02139. Email: arodal{at}mit.edu
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.
Key words: actin; endocytosis; F-BAR; Drosophila; neuromuscular junction; synaptic growth
Received May 21, 2008;
revised July 1, 2008;
accepted July 11, 2008.
Correspondence should be addressed to Avital A. Rodal, The Picower Institute for Learning and Memory, Departments of Biology and Brain and Cognitive Sciences, Massachusetts Institute of Technology, 46-3251, 43 Vassar Street, Cambridge, MA 02139. Email: arodal{at}mit.edu
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