title: E-cadherin-mediated cell-cell attachment activates Cdc42.
abstract: E-cadherin is a transmembrane protein that mediates Ca(2+)-dependent cell-cell adhesion. Cdc42, a member of the Rho family of small GTPases, participates in cytoskeletal rearrangement and cell cycle progression. Recent evidence reveals that members of the Rho family modulate E-cadherin function. To further examine the role of Cdc42 in E-cadherin-mediated cell-cell adhesion, we developed an assay for active Cdc42 using the GTPase-binding domain of the Wiskott-Aldrich syndrome protein. Initiation of E-cadherin-mediated cell-cell attachment significantly increased in a time-dependent manner the amount of active Cdc42 in MCF-7 epithelial cell lysates. By contrast, Cdc42 activity was not increased under identical conditions in MCF-7 cells incubated with anti-E-cadherin antibodies nor in MDA-MB-231 (E-cadherin negative) epithelial cells. By fusing the Wiskott-Aldrich syndrome protein/GTPase-binding domain to a green fluorescent protein, activation of endogenous Cdc42 by E-cadherin was demonstrated in live cells. These data indicate that E-cadherin activates Cdc42, demonstrating bi-directional interactions between the Rho- and E-cadherin signaling pathways.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: D B
authors.initials: DB
authors.lastname: Sacks
mesh_terms: D015820:Cadherins / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects*; D046508:Culture Techniques; D004789:Enzyme Activation; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured; D051316:Wiskott-Aldrich Syndrome Protein; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D015820:Cadherins; D008164:Luminescent Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011506:Proteins; D011993:Recombinant Fusion Proteins; C495767:WAS protein, human; D051316:Wiskott-Aldrich Syndrome Protein; D049452:Green Fluorescent Proteins; D020764:cdc42 GTP-Binding Protein