Abstract
We identified a novel adaptor protein that contains a Src homology (SH)3 domain, SH3 binding proline-rich sequences, and a leucine zipper-like motif and termed this protein WASP interacting SH3 protein (WISH). WISH is expressed predominantly in neural tissues and testis. It bound Ash/Grb2 through its proline-rich regions and neural Wiskott-Aldrich syndrome protein (N-WASP) through its SH3 domain. WISH strongly enhanced N-WASP-induced Arp2/3 complex activation independent of Cdc42 in vitro, resulting in rapid actin polymerization. Furthermore, coexpression of WISH and N-WASP induced marked formation of microspikes in Cos7 cells, even in the absence of stimuli. An N-WASP mutant (H208D) that cannot bind Cdc42 still induced microspike formation when coexpressed with WISH. We also examined the contribution of WISH to a rapid actin polymerization induced by brain extract in vitro. Arp2/3 complex was essential for brain extract-induced rapid actin polymerization. Addition of WISH to extracts increased actin polymerization as Cdc42 did. However, WISH unexpectedly could activate actin polymerization even in N-WASP-depleted extracts. These findings suggest that WISH activates Arp2/3 complex through N-WASP-dependent and -independent pathways without Cdc42, resulting in the rapid actin polymerization required for microspike formation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actin-Related Protein 2
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Actin-Related Protein 3
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Actins / metabolism*
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Adaptor Proteins, Signal Transducing*
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Amino Acid Sequence
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Animals
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Blotting, Northern
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Blotting, Western
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Brain Chemistry
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Carrier Proteins / chemistry
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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Cattle
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Cell Line
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Cell Surface Extensions / metabolism
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Culture Media, Serum-Free
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Cytoskeletal Proteins*
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GRB2 Adaptor Protein
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Genes, Reporter
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Humans
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Leucine Zippers
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Molecular Sequence Data
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Muscle Proteins*
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Nerve Tissue Proteins / metabolism*
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Polymers / metabolism
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Protein Binding
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Proteins / metabolism
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Rats
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Wiskott-Aldrich Syndrome
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Wiskott-Aldrich Syndrome Protein, Neuronal
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cdc42 GTP-Binding Protein / metabolism*
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src Homology Domains
Substances
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ACTR2 protein, human
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ACTR3 protein, human
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Actin-Related Protein 2
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Actin-Related Protein 3
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Actins
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Adaptor Proteins, Signal Transducing
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Carrier Proteins
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Culture Media, Serum-Free
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Cytoskeletal Proteins
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GRB2 Adaptor Protein
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GRB2 protein, human
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Grb2 protein, rat
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Muscle Proteins
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NCKIPSD protein, human
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Nckipsd protein, mouse
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Nerve Tissue Proteins
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Polymers
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Proteins
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Recombinant Fusion Proteins
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WASL protein, human
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Wasl protein, rat
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Wiskott-Aldrich Syndrome Protein, Neuronal
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cdc42 GTP-Binding Protein