title: Dual role of H-Ras in regulation of lymphocyte function antigen-1 activity by stromal cell-derived factor-1alpha: implications for leukocyte transmigration.
abstract: We investigated the role of H-Ras in chemokine-induced integrin regulation in leukocytes. Stimulation of Jurkat T cells with the CXC chemokine stromal cell-derived factor-1alpha (SDF-1alpha) resulted in a rapid increase in the phosphorylation, i.e., activation of extracellular signal receptor-activated kinase (ERK) but not c-Jun NH(2)-terminal kinase or p38 kinase, and phosphorylation of Akt, reflecting phosphatidylinositol 3-kinase (PI3-K) activation. Phosphorylation of ERK in Jurkat cells was enhanced and attenuated by expression of dominant active (D12) or inactive (N17) forms of H-Ras, respectively, while N17 H-Ras abrogated SDF-1alpha-induced Akt phosphorylation. SDF-1alpha triggered a transient regulation of adhesion to intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 mediated by lymphocyte function antigen-1 (LFA-1) and very late antigen-4 (VLA-4), respectively, and a rapid increase in LFA-1 binding to soluble ICAM-1.Ig, which was inhibited by D12 but not N17 H-Ras. Both D12 and N17 H-Ras abrogated the regulation of LFA-1 but not VLA-4 avidity, and impaired LFA-1-mediated transendothelial chemotaxis but not VLA-4-dependent transmigration induced by SDF-1alpha. Analysis of the mutant Jurkat J19 clone revealed LFA-1 with constitutively high affinity and reduced ERK phosphorylation, which were partially restored by expression of active H-Ras. Inhibition of PI3-K blocked the up-regulation of Jurkat cell adhesion to ICAM-1 by SDF-1alpha, whereas inhibition of mitogen-activated protein kinase kinase impaired the subsequent down-regulation and blocking both pathways abrogated LFA-1 regulation. Our data suggest that inhibition of initial PI3-K activation by inactive H-Ras or sustained activation of an inhibitory ERK pathway by active H-Ras prevail to abolish LFA-1 regulation and transendothelial migration induced by SDF-1alpha in leukocytes, establishing a complex and bimodal involvement of H-Ras.
authors.affiliation: Institute for Prevention of Cardiovascular Disease, Ludwig-Maximilians-University, Munich, Germany 80336.
authors.forename: K S
authors.initials: KS
authors.lastname: Weber
authors.forename: G
authors.initials: G
authors.lastname: Ostermann
authors.forename: A
authors.initials: A
authors.lastname: Zernecke
authors.forename: A
authors.initials: A
authors.lastname: Schröder
authors.forename: L B
authors.initials: LB
authors.lastname: Klickstein
authors.forename: C
authors.initials: C
authors.lastname: Weber
mesh_terms: D002465:Cell Movement / Q000502:physiology*; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism* / Q000494:pharmacology; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology; D004727:Endothelium / Q000166:cytology / Q000378:metabolism; D011905:Genes, ras / Q000235:genetics / Q000502:physiology*; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000187:drug effects / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells; D007962:Leukocytes / Q000502:physiology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000187:drug effects / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism / Q000494:pharmacology; D016201:Receptors, Lymphocyte Homing / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D039041:Integrin alpha4beta1; D016023:Integrins; D048031:JNK Mitogen-Activated Protein Kinases; D016169:Lymphocyte Function-Associated Antigen-1; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D016201:Receptors, Lymphocyte Homing; D048051:p38 Mitogen-Activated Protein Kinases; C515255:CXCL12 protein, human; C494918:AKT1 protein, human