title: Leukocyte-endothelium interaction promotes SDF-1-dependent polarization of CXCR4.
abstract: Chemokine-driven migration is accompanied by polarization of the cell body and of the intracellular signaling machinery. The extent to which chemokine receptors polarize during chemotaxis is currently unclear. To analyze the distribution of the chemokine receptor CXCR4 during SDF-1 (CXCL12)-induced chemotaxis, we retrovirally expressed a CXCR4-GFP fusion protein in the CXCR4-deficient human hematopoietic progenitor cell line KG1a. This KG1a CXCR4-GFP cell line showed full restoration of SDF-1 responsiveness in assays detecting activation of ERK1/2 phosphorylation, actin polymerization, adhesion to endothelium under conditions of physiological flow, and (transendothelial) chemotaxis. When adhered to cytokine-activated endothelium in the absence of SDF-1, CXCR4 did not localize to the leading edge of the cell but was uniformly distributed over the plasma membrane. In contrast, when SDF-1 was immobilized on cytokine-activated endothelium, the CXCR4-GFP receptors that were present on the cell surface markedly redistributed to the leading edge of migrating cells. In addition, CXCR4-GFP co-localized with lipid rafts in the leading edge of SDF-1-stimulated cells, at the sites of contact with the endothelial surface. Inhibition of lipid raft formation prevents SDF-1-dependent migration, internalization of CXCR4, and polarization to the leading edge of CXCR4, indicating that CXCR4 surface expression and signaling requires lipid rafts. These data show that SDF-1, immobilized on activated human endothelium, induces polarization of CXCR4 to the leading edge of migrating cells, revealing co-operativity between chemokine and substrate in the control of cell migration.
authors.affiliation: Sanquin Research at CLB, the Landsteiner Laboratorium, Amsterdam, The Netherlands.
authors.forename: Jaap D
authors.initials: JD
authors.lastname: van Buul
authors.forename: Carlijn
authors.initials: C
authors.lastname: Voermans
authors.forename: Jose
authors.initials: J
authors.lastname: van Gelderen
authors.forename: Eloise C
authors.initials: EC
authors.lastname: Anthony
authors.forename: C Ellen
authors.initials: CE
authors.lastname: van der Schoot
authors.forename: Peter L
authors.initials: PL
authors.lastname: Hordijk
mesh_terms: D000199:Actins / Q000378:metabolism; D018952:Antigens, CD34 / Q000096:biosynthesis; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism / Q000502:physiology*; D002633:Chemotaxis; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004727:Endothelium / Q000166:cytology / Q000378:metabolism*; D005312:Fetal Blood / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D007150:Immunohistochemistry; D007962:Leukocytes / Q000378:metabolism*; D050356:Lipid Metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D021962:Membrane Microdomains; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D019718:Receptors, CXCR4 / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells; D013997:Time Factors
chemical_list: D000199:Actins; D018952:Antigens, CD34; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D018076:DNA, Complementary; D008164:Luminescent Proteins; D019718:Receptors, CXCR4; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases