title: Essential role of neural Wiskott-Aldrich syndrome protein in podosome formation and degradation of extracellular matrix in src-transformed fibroblasts.
abstract: Transformation of cells by the src oncogene causes dramatic changes in adhesive structures. In v-src-transformed 3Y1 rat fibroblasts (3Y1-src), there are actin-rich protrusive structures called podosomes by which attachment to the extracellular matrix is thought to occur. In this study, we found that neural Wiskott-Aldrich syndrome protein (N-WASP) colocalizes with filamentous actin (F-actin) in podosomes. Expression of dominant-negative mutants of N-WASP, Deltacof N-WASP and DeltaVPH N-WASP, both of which are incapable of activating the Arp2/3 complex, suppressed podosome formation, suggesting that N-WASP is essential in this process. Localization of N-WASP in podosomes appears to be attributable to interaction between N-WASP and the SH3 domain of cortactin. Indeed, microinjection of the cortactin SH3 domain suppressed podosome formation. We also observed that 3Y1-src cells cultured on fibronectin degrade the fibronectin primarily at the podosomes and that the inhibition of podosome formation by Deltacof N-WASP abolishes the fibronectin degradation. These results suggest the importance of N-WASP in podosome formation and extracellular matrix degradation, which are processes thought to underlie the invasive phenotype of 3Y1-src cells.
authors.affiliation: Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: Kiyohito
authors.initials: K
authors.lastname: Mizutani
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Miki
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maruta
authors.forename: Tadaomi
authors.initials: T
authors.lastname: Takenawa
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D051356:Cortactin; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D016391:Genes, src / Q000502:physiology*; D008840:Microfilament Proteins / Q000378:metabolism; D009154:Mutation; D011506:Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D051316:Wiskott-Aldrich Syndrome Protein
chemical_list: D000199:Actins; D051356:Cortactin; C495870:Cttn protein, rat; D008840:Microfilament Proteins; D011506:Proteins; C495769:Was protein, rat; D051316:Wiskott-Aldrich Syndrome Protein