Ephrin stimulation modulates T cell chemotaxis.
Eph receptor tyrosine kinases and their ligands, the ephrins, are known to play an important role in regulating cell migration and targeting in neuronal and endothelial cells. Recently, it has been shown that lymphoid cells also express Eph receptors, raising the possibility that Eph receptors may similarly regulate lymphocyte migration. Chemotaxis in response to soluble chemokine factors is an essential facet of T cell biology. We demonstrate here that T cell chemotaxis in response to both the stromal cell-derived factor (SDF)-1alpha and macrophage inflammatory protein 3beta chemokines is modulated by costimulation with ephrins. Both ephrin-A and ephrin-B ligands were found to modify the chemotactic responses of a T cell line and primary T cells. Ephrin-A1, in particular, strongly inhibited chemotaxis. In accordance with the tyrosine kinase activity of EphA receptors, ephrin-A1 stimulation induced rapid intracellular tyrosine phosphorylation in T cells. Although strongly inhibiting chemotaxis, ephrin-A1 costimulus did not affect many of the signaling events downstream of the SDF-1alpha receptor CXCR4, including calcium flux and activation of MAPK. Rather, ephrin-A1 altered the balance of small G protein activity in T cells. Ephrin-A1 stimulation prevented SDF-1alpha-induced activation of cdc42, while simultaneously inducing rho activation. Ultimately, ephrin-A1 was found to inhibit chemokine-induced actin polymerization, thereby blocking migration. Ubiquitous ephrin expression in vivo creates enormous potential for T cells to encounter these ligands, suggesting that Eph receptors and ephrins may be important regulators of T cell migration.
Sharfe
Nigel
N
Division of Immunology and Allergy, Department of Pediatrics, Infection, Immunity, Injury and Repair Program, Research Institute, The Hospital for Sick Children and the University of Toronto, Toronto, Canada.
Freywald
Andrew
A
Toro
Ana
A
Dadi
Harjit
H
Roifman
Chaim
C
D000199:Actins / Q000378:metabolism; D054415:Chemokine CCL19; D054377:Chemokine CXCL12; D019742:Chemokines, CC / Q000494:pharmacology; D019743:Chemokines, CXC / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D002648:Child; D036382:Ephrin-A1 / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D019169:Jurkat Cells; D010766:Phosphorylation; D019718:Receptors, CXCR4 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D000199:Actins; C515460:CCL19 protein, human; C515255:CXCL12 protein, human; D054415:Chemokine CCL19; D054377:Chemokine CXCL12; D019742:Chemokines, CC; D019743:Chemokines, CXC; D036382:Ephrin-A1; D019718:Receptors, CXCR4; D014443:Tyrosine; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins