title: Wnt Signalling Promotes Actin Dynamics during Axon Remodelling through the Actin-Binding Protein Eps8.
abstract: Upon arrival at their synaptic targets, axons slow down their growth and extensively remodel before the assembly of presynaptic boutons. Wnt proteins are target-derived secreted factors that promote axonal remodelling and synaptic assembly. In the developing spinal cord, Wnts secreted by motor neurons promote axonal remodelling of NT-3 responsive dorsal root ganglia neurons. Axon remodelling induced by Wnts is characterised by growth cone pausing and enlargement, processes that depend on the re-organisation of microtubules. However, the contribution of the actin cytoskeleton has remained unexplored. Here, we demonstrate that Wnt3a regulates the actin cytoskeleton by rapidly inducing F-actin accumulation in growth cones from rodent DRG neurons through the scaffold protein Dishevelled-1 (Dvl1) and the serine-threonine kinase Gsk3β. Importantly, these changes in actin cytoskeleton occurs before enlargement of the growth cones is evident. Time-lapse imaging shows that Wnt3a increases lamellar protrusion and filopodia velocity. In addition, pharmacological inhibition of actin assembly demonstrates that Wnt3a increases actin dynamics. Through a yeast-two hybrid screen, we identified the actin-binding protein Eps8 as a direct interactor of Dvl1, a scaffold protein crucial for the Wnt signalling pathway. Gain of function of Eps8 mimics Wnt-mediated axon remodelling, whereas Eps8 silencing blocks the axon remodelling activity of Wnt3a. Importantly, blockade of the Dvl1-Eps8 interaction completely abolishes Wnt3a-mediated axonal remodelling. These findings demonstrate a novel role for Wnt-Dvl1 signalling through Eps8 in the regulation of axonal remodeling.
authors.affiliation: Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom.
authors.forename: Eleanna
authors.initials: E
authors.lastname: Stamatakou
authors.affiliation: Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom.
authors.forename: Monica
authors.initials: M
authors.lastname: Hoyos-Flight
authors.affiliation: Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom.
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Salinas
mesh_terms: D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D045744:Cell Line, Tumor; D000072261:Dishevelled Proteins; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D060449:Wnt Signaling Pathway / Q000187:drug effects; D060509:Wnt3A Protein / Q000494:pharmacology
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D000072261:Dishevelled Proteins; C000606579:Dvl1 protein, mouse; C000606580:Dvl1 protein, rat; C083430:Eps8 protein, mouse; C498142:Eps8 protein, rat; D010750:Phosphoproteins; D060509:Wnt3A Protein; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3