title: Drebrin preserves endothelial integrity by stabilizing nectin at adherens junctions.
abstract: Regulation of cell-cell contacts is essential for integrity of the vascular endothelium. Here, a critical role of the F-actin-binding protein drebrin in maintaining endothelial integrity is revealed under conditions mimicking vascular flow. Drebrin knockdown leads to weakening of cell-cell contacts, characterized by loss of nectin from adherens junctions and its subsequent lysosomal degradation. Immunoprecipitation, FRAP and mitochondrial re-targeting experiments show that nectin stabilization occurs through a chain of interactions: drebrin binding to F-actin, interaction of drebrin and afadin through their polyproline and PR1-2 regions, and recruitment of nectin through the PDZ region of afadin. Key elements are modules in drebrin that confer binding to afadin and F-actin. Evidence for this was obtained using constructs containing the PDZ region of afadin coupled to the F-actin-binding region of drebrin or to lifeact, which restore junctional nectin under knockdown of drebrin or of both drebrin and afadin. Drebrin, containing binding sites for both afadin and F-actin, is thus uniquely equipped to stabilize nectin at endothelial junctions and to preserve endothelial integrity under vascular flow.
authors.affiliation: Institute for Medical Microbiology, Virology and Hygiene, University Medical Center Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Rehm
authors.forename: Linda
authors.initials: L
authors.lastname: Panzer
authors.forename: Vanessa
authors.initials: V
authors.lastname: van Vliet
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Genot
authors.forename: Stefan
authors.initials: S
authors.lastname: Linder
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D018929:Cell Culture Techniques; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D000075983:Nectins; D009479:Neuropeptides / Q000378:metabolism*; D011485:Protein Binding; D014162:Transfection
chemical_list: D000199:Actins; D015815:Cell Adhesion Molecules; D000075983:Nectins; D009479:Neuropeptides; C053386:drebrins
keywords: Actin cytoskeleton; Afadin; Cell–cell junctions; Drebrin; Endothelial cells; Nectin