title: WICH, a member of WASP-interacting protein family, cross-links actin filaments.
abstract: In yeast, Verprolin plays an important role in rearrangement of the actin cytoskeleton. There are three mammalian homologues of Verprolin, WIP, CR16, and WICH, and all of them bind actin and Wiskott-Aldrich syndrome protein (WASP) and/or neural-WASP. Here, we describe a novel function of WICH. In vitro co-sedimentation analysis revealed that WICH not only binds to actin filaments but also cross-links them. Fluorescence and electron microscopy detected that this cross-linking results in straight bundled actin filaments. Overexpression of WICH alone in cultured fibroblast caused the formation of thick actin fibers. This ability of WICH depended on its own actin cross-linking activity. Importantly, the actin cross-linking activity of WICH was modified through a direct association with N-WASP. Taken together, these data suggest that WICH induces a bundled form of actin filament with actin cross-linking activity and the association with N-WASP suppresses that activity. WICH thus appears to be a novel actin bundling protein.
authors.affiliation: Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Mianato-ku, Tokyo 108-8639, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kato
authors.forename: Tadaomi
authors.initials: T
authors.lastname: Takenawa
mesh_terms: D016475:3T3 Cells; D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000378:metabolism*; D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal
chemical_list: D000199:Actins; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; C465744:WIPF2 protein, human; C495772:Wasl protein, mouse; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal