Vinexin: A Novel Vinculin-Binding Protein with Multiple SH3 Domains Enhances Actin Cytoskeletal Organization

• Published in: The Journal of cell biology Vol. 144; no. 1; pp. 59 - 69
• Main Authors: Kioka, Noriyuki, Sakata, Shohei, Kawauchi, Takeshi, Amachi, Teruo, Akiyama, Steven K., Okazaki, Kenji, Yaen, Christopher, Yamada, Kenneth M., Aota, Shin-ichi
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 11.01.1999; The Rockefeller University Press
• Subjects: 3T3 Cells; Actins; Actins - metabolism; Adaptor Proteins, Signal Transducing; Amino Acid Sequence; Animals; Base Sequence; Binding Sites; Cell adhesion; Cell Line; Cell lines; Cell Movement; Cells; Chickens; Chromosome Mapping; Cloning, Molecular; Cytoskeleton - physiology; DNA, Complementary; Epithelial cells; Focal adhesions; Gene Expression; Humans; LLC PK1 cells; Mice; Molecular Sequence Data; Muscle Proteins - genetics; Muscle Proteins - metabolism; NIH 3T3 cells; Plasmids; Rabbits; Sequence Homology, Amino Acid; src Homology Domains; Swine; Tissue Distribution; Vinculin - genetics; Vinculin - metabolism
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.144.1.59

Using the yeast two-hybrid system and an in vitro binding assay, we have identified a novel protein termed vinexin as a vinculin-binding protein. By Northern blotting, we identified two types of vinexin mRNA that were 3 and 2 kb in length. Screening for full-length cDNA clones and sequencing indicated that the two mRNA encode 82- and 37-kD polypeptides termed vinexin α and β, respectively. Both forms of vinexin share a common carboxyl-terminal sequence containing three SH3 domains. The larger vinexin α contains an additional amino-terminal sequence. The interaction between vinexin and vinculin was mediated by two SH3 domains of vinexin and the proline-rich region of vinculin. When expressed, vinexin α and β localized to focal adhesions in NIH 3T3 fibroblasts, and to cell-cell junctions in epithelial LLC-PK1 cells. Furthermore, expression of vinexin increased focal adhesion size. Vinexin α also promoted upregulation of actin stress fiber formation. In addition, cell lines stably expressing vinexin β showed enhanced cell spreading on fibronectin. These data identify vinexin as a novel focal adhesion and cell-cell adhesion protein that binds via SH3 domains to the hinge region of vinculin, which can enhance actin cytoskeletal organization and cell spreading.