E-selectin-dependent signaling via the mitogen-activated protein kinase pathway in vascular endothelial cells

E-selectin, a cytokine-inducible adhesion molecule, supports rolling and st able arrest of leukocytes on activated vascular endothelium, Previous studi es have suggested that this transmembrane protein can also transduce signal s into the endothelial cell. We now demonstrate activation of the mitogen-a ctivated protein kinase (MAPK) signaling cascade in cultured HUVEC in respo nse to E-selectin-dependent leukocyte adhesion and Ab-mediated cross-linkin g of cell surface E-selectin, Adhesion of increasing numbers of HL60 cells to IL-1 beta-activated HUVEC stimulated robust increases in MAPK activity t hat were abrogated by an E-selectin blocking Ab, Cross-linking of cell surf ace E-selectin with Abs, as a mimic of multivalent ligand engagement, stron gly stimulated MAPK/extracellular signal-related kinase (ERK) kinase (MEK)- dependent MAPK activation and concomitant upregulation of mRNA for c-fos, a n immediate early response gene, whereas Ab cross-linking of BLA class I mo lecules (present at comparable density) failed to do so. Coimmunoprecipitat ion documented Pas, Raf-1 and, phospho-MEK complex formation. Unactivated H UVEC transduced with a full-length adenoviral E-selectin construct also exh ibited cross-link-induced MAPK activation, macromolecular complex formation , and c-fos up-regulation, whereas HUVEC transduced with a cytoplasmic doma in deletion mutant failed to respond. These observations indicate that E-se lectin can transduce an activating stimulus via the MAPK cascade into the e ndothelial cell during leukocyte adhesion.