VCAM-1-mediated Rac signaling controls endothelial cell-cell contacts and leukocyte transmigration

Am J Physiol Cell Physiol. 2003 Aug;285(2):C343-52. doi: 10.1152/ajpcell.00048.2003. Epub 2003 Apr 16.


Leukocyte adhesion is mediated totally and transendothelial migration partially by heterotypic interactions between the beta1- and beta2-integrins on the leukocytes and their ligands, Ig-like cell adhesion molecules (Ig-CAM), VCAM-1, and ICAM-1, on the endothelium. Both integrins and Ig-CAMs are known to have signaling capacities. In this study we analyzed the role of VCAM-1-mediated signaling in the control of endothelial cell-cell adhesion and leukocyte transendothelial migration. Antibody-mediated cross-linking of VCAM-1 on IL-1beta-activated primary human umbilical vein endothelial cells (pHUVEC) induced actin stress fiber formation, contractility, and intercellular gaps. The effects induced by VCAM-1 cross-linking were inhibited by C3 toxin, indicating that the small GTPase p21Rho is involved. In addition, the effects of VCAM-1 were accompanied by activation of Rac, which we recently showed induce intercellular gaps in pHUVEC in a Rho-dependent fashion. With the use of a cell-permeable peptide inhibitor, it was shown that Rac signaling is required for VCAM-1-mediated loss of cell-cell adhesion. Furthermore, VCAM-1-mediated signaling toward cell-cell junctions was accompanied by, and dependent on, Rac-mediated production of reactive oxygen species and activation of p38 MAPK. In addition, it was found that inhibition of Rac-mediated signaling blocks transendothelial migration of monocytic U937 cells. Together, these data indicate that VCAM-1-induced, Rac-dependent signaling plays a key role in the modulation of vascular-endothelial cadherin-mediated endothelial cell-cell adhesion and leukocyte extravasation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / pharmacology
  • Botulinum Toxins / pharmacology
  • Cell Adhesion / drug effects
  • Cell Adhesion / physiology*
  • Cell Communication / drug effects
  • Cell Communication / physiology*
  • Cell Line
  • Chemotaxis, Leukocyte / drug effects
  • Chemotaxis, Leukocyte / physiology*
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Interleukin-1 / pharmacology
  • Leukocytes / cytology
  • Leukocytes / drug effects
  • Leukocytes / metabolism*
  • Mitogen-Activated Protein Kinases / drug effects
  • Mitogen-Activated Protein Kinases / metabolism
  • Peptide Fragments / pharmacology
  • Reactive Oxygen Species / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Vascular Cell Adhesion Molecule-1 / drug effects
  • Vascular Cell Adhesion Molecule-1 / metabolism*
  • p38 Mitogen-Activated Protein Kinases
  • rac GTP-Binding Proteins / drug effects
  • rac GTP-Binding Proteins / metabolism*
  • rhoA GTP-Binding Protein / drug effects
  • rhoA GTP-Binding Protein / metabolism


  • Enzyme Inhibitors
  • Interleukin-1
  • Peptide Fragments
  • Reactive Oxygen Species
  • Vascular Cell Adhesion Molecule-1
  • ADP Ribose Transferases
  • exoenzyme C3, Clostridium botulinum
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Botulinum Toxins
  • rac GTP-Binding Proteins
  • rhoA GTP-Binding Protein