Drebrin preserves endothelial integrity by stabilizing nectin at adherens junctions

J Cell Sci. 2013 Aug 15;126(Pt 16):3756-69. doi: 10.1242/jcs.129437. Epub 2013 Jun 7.

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.

Keywords: Actin cytoskeleton; Afadin; Cell–cell junctions; Drebrin; Endothelial cells; Nectin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / metabolism
  • Adherens Junctions / metabolism*
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism*
  • Cell Culture Techniques
  • Human Umbilical Vein Endothelial Cells / cytology*
  • Human Umbilical Vein Endothelial Cells / metabolism*
  • Humans
  • Nectins
  • Neuropeptides / metabolism*
  • Protein Binding
  • Transfection

Substances

  • Actins
  • Cell Adhesion Molecules
  • Nectins
  • Neuropeptides
  • drebrins