During embryonic development, vast numbers of neurons must form connections with their proper targets. Axons are guided to their targets by growth cones, which integrate and convert guidance signals into mechanical forces required for locomotion. Movement arises from dynamic regulation of cytoskeletal polymers and associated proteins. The Ena/VASP protein family functions in various axon guidance pathways and is known to regulate the assembly of actin filaments. Ena/VASP proteins are concentrated in the tips of growth cone filopodia, where the initial response to guidance signals occurs. Several signaling pathways implicated in axon guidance regulate Ena/VASP function. Therefore, Ena/VASP proteins are well positioned to act as key convergence points between signals from guidance pathways and the actin cytoskeleton. We will test the hypothesis that Ena/VASP proteins regulate actin remodeling in response to guidance signals. We propose to examine the role of Ena/VASP in growth cone guidance and translocation using high-resolution light and electron microscopy to analyze cytoskeletal dynamics and geometry. We will also employ genetic manipulation to perturb Ena/VASP function and biochemical approaches to study Ena/VASP's role in signaling pathways. This work should yield valuable insight into how the nervous system develops and how to design methods to repair it after injury.
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