title: Novel role of CD47 in rat microvascular endothelium: signaling and regulation of T-cell transendothelial migration.
abstract: OBJECTIVE
  Although endothelial CD47, a member of the immunoglobulin superfamily, has been implicated in leukocyte diapedesis, its capacity for intracellular signaling and physical localization during this process has not been addressed in detail. This study examined endothelial CD47 spatiotemporal behavior and signaling pathways involved in regulating T-cell transendothelial migration.
  
  
  RESULTS
  By biochemical methods, transmigration assays, and live-cell microscopy techniques, we show that endothelial CD47 engagement results in intracellular calcium mobilization, increased permeability, and activation of Src and AKT1/phosphoinositide 3-kinase in brain microvascular endothelial cells. These signaling pathways converge to induce cytoskeleton remodeling and vascular endothelial cadherin phosphorylation, which are necessary steps during T-cell transendothelial migration. In addition, during T-cell migration, transmigratory cups and podo-prints enriched in CD47 appear on the surface of the endothelium, indicating that the spatial distribution of CD47 changes after its engagement. Consistent with previous findings of intercellular adhesion molecule 1, blockade of CD47 results in decreased T-cell transmigration across microvascular endothelium. The overlapping effect of intercellular adhesion molecule 1 and CD47 suggests their involvement in different steps of the diapedesis process.
  
  
  CONCLUSIONS
  These data reveal a novel role for CD47-mediated signaling in the control of the molecular network governing endothelial-dependent T-cell diapedesis.
authors.affiliation: From the Department of Pathology, Center for Excellence in Vascular Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (R.M., G.N., F.W.L.); Department of Medicine, Center for Vascular Biology Research, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (R.M., C.V.C.); and Department of Cell Biology, Institute of Ophthalmology, UCL, London, United Kingdom (R.M., J.G.).
authors.forename: Roberta
authors.initials: R
authors.lastname: Martinelli
authors.forename: Gail
authors.initials: G
authors.lastname: Newton
authors.forename: Christopher V
authors.initials: CV
authors.lastname: Carman
authors.forename: John
authors.initials: J
authors.lastname: Greenwood
authors.forename: Francis W
authors.initials: FW
authors.lastname: Luscinskas
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000098:blood supply; D051928:CD47 Antigen / Q000276:immunology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007365:Intercellular Junctions / Q000276:immunology / Q000378:metabolism; D055806:Microvessels / Q000276:immunology / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D057705:Transendothelial and Transepithelial Migration / Q000276:immunology*
chemical_list: D000199:Actins; D051928:CD47 Antigen; C584934:CD47 protein, rat; D002118:Calcium
keywords: cell adhesion molecules; endothelium; inflammation; leukocytes; transendothelial migration