title: Cytoskeleton assembly at endothelial cell-cell contacts is regulated by alphaII-spectrin-VASP complexes.
abstract: Directed cortical actin assembly is the driving force for intercellular adhesion. Regulated by phosphorylation, vasodilator-stimulated phosphoprotein (VASP) participates in actin fiber formation. We screened for endothelial proteins, which bind to VASP, dependent on its phosphorylation status. Differential proteomics identified alphaII-spectrin as such a VASP-interacting protein. alphaII-Spectrin binds to the VASP triple GP(5)-motif via its SH3 domain. cAMP-dependent protein kinase-mediated VASP phosphorylation at Ser157 inhibits alphaII-spectrin-VASP binding. VASP is dephosphorylated upon formation of cell-cell contacts and in confluent, but not in sparse cells, alphaII-spectrin colocalizes with nonphosphorylated VASP at cell-cell junctions. Ectopic expression of the alphaII-spectrin SH3 domain at cell-cell contacts translocates VASP, initiates cortical actin cytoskeleton formation, stabilizes cell-cell contacts, and decreases endothelial permeability. Conversely, the permeability of VASP-deficient endothelial cells (ECs) and microvessels of VASP-null mice increases. Reconstitution of VASP-deficient ECs rescues barrier function, whereas alphaII-spectrin binding-deficient VASP mutants fail to restore elevated permeability. We propose that alphaII-spectrin-VASP complexes regulate cortical actin cytoskeleton assembly with implications for vascular permeability.
authors.affiliation: Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, D-97080 Würzburg, Germany.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Benz
authors.forename: Constanze
authors.initials: C
authors.lastname: Blume
authors.forename: Jan
authors.initials: J
authors.lastname: Moebius
authors.forename: Chris
authors.initials: C
authors.lastname: Oschatz
authors.forename: Kai
authors.initials: K
authors.lastname: Schuh
authors.forename: Albert
authors.initials: A
authors.lastname: Sickmann
authors.forename: Ulrich
authors.initials: U
authors.lastname: Walter
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Feller
authors.forename: Thomas
authors.initials: T
authors.lastname: Renné
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure*; D007365:Intercellular Junctions / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D010766:Phosphorylation; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D000098662:Vasodilator-Stimulated Phosphoprotein; D013049:Spectrin
chemical_list: D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D000098662:Vasodilator-Stimulated Phosphoprotein; D013049:Spectrin