PMID:12147689

Citation	Benesch, S, Lommel, S, Steffen, A, Stradal, TE, Scaplehorn, N, Way, M, Wehland, J and Rottner, K (2002) Phosphatidylinositol 4,5-biphosphate (PIP2)-induced vesicle movement depends on N-WASP and involves Nck, WIP, and Grb2. J. Biol. Chem. 277:37771-6
Abstract	Wiskott-Aldrich syndrome protein (WASP)/Scar family proteins promote actin polymerization by stimulating the actin-nucleating activity of the Arp2/3 complex. While Scar/WAVE proteins are thought to be involved in lamellipodia protrusion, the hematopoietic WASP has been implicated in various actin-based processes such as chemotaxis, podosome formation, and phagocytosis. Here we show that the ubiquitously expressed N-WASP is essential for actin assembly at the surface of endomembranes induced as a consequence of increased phosphatidylinositol 4,5-biphosphate (PIP2) levels. This process resulting in the motility of intracellular vesicles at the tips of actin comets involved the recruitment of the Src homology 3 (SH3)-SH2 adaptor proteins Nck and Grb2 as well as of WASP interacting protein (WIP). Reconstitution of vesicle movement in N-WASP-defective cells by expression of various N-WASP mutant proteins revealed three independent domains capable of interaction with the vesicle surface, of which both the WH1 and the polyproline domains contributed significantly to N-WASP recruitment and/or activation. In contrast, the direct interaction of N-WASP with the Rho-GTPase Cdc42 was not required for reconstitution of vesicle motility. Our data reveal a distinct cellular phenotype for N-WASP loss of function, which adds to accumulating evidence that the proposed link between actin and membrane dynamics may, at least partially, be reflected by the actin-based movement of vesicles through the cytoplasm.
Links	PubMed Online version:10.1074/jbc.M204145200
Keywords	Adaptor Proteins, Signal Transducing; Animals; Base Sequence; Brain/metabolism; Carrier Proteins/genetics; Carrier Proteins/metabolism; Cytoskeletal Proteins; DNA Primers; Fibroblasts/cytology; Fibroblasts/physiology; GRB2 Adaptor Protein; Gene Deletion; Green Fluorescent Proteins; Humans; Intracellular Signaling Peptides and Proteins; Luminescent Proteins/genetics; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Movement/physiology; Nerve Tissue Proteins/genetics; Nerve Tissue Proteins/metabolism; Oncogene Proteins/genetics; Oncogene Proteins/metabolism; Phosphatidylinositol 4,5-Diphosphate/pharmacology; Proteins/genetics; Proteins/metabolism; Recombinant Fusion Proteins/metabolism; Reverse Transcriptase Polymerase Chain Reaction; Wiskott-Aldrich Syndrome/genetics; Wiskott-Aldrich Syndrome Protein, Neuronal; src Homology Domains
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