Integrin-dependent homotypic adhesion of neutrophils. Arachidonic acid activates Raf-1/Mek/Erk via a 5-lipoxygenase- dependent pathway.
AA stimulates integrin-dependent neutrophil adhesion, a critical early step in acute inflammation. However, neither the signaling pathway(s) of AA-stimulated adhesion, nor whether AA acts directly or through the generation of active metabolites, has been elucidated. Previously, we have observed a tight association between neutrophil Erk activation and homotypic adhesion in response to chemoattractants acting through G protein-linked receptors. We now report a similar association between homotypic adhesion and Erk activation in response to AA. Erk activation was cyclooxygenase independent and required AA metabolism to 5(S)- hydroperoxyeicosatetraenoic acid (5-HpETE) via 5-lipoxygenase, but not the further lipoxygenase-dependent metabolism of 5-HpETE to leukotrienes. AA stimulation of Erk was accompanied by Raf-1 activation and was sensitive to inhibitors of Raf-1 and Mek. Whereas activation of Erk by AA was pertussis toxin sensitive, [3H]-AA binding to neutrophils was not saturable, suggesting that an AA metabolite activates a G protein. Consistent with this hypothesis, Erk activation by 5(S)-hydroxyeicosatetraenoic acid (5-HETE; lipoxygenase-independent metabolite of 5-HpETE) was also pertussis toxin sensitive. These data suggest that a 5-lipoxygenase metabolite of AA, e.g., 5-HETE, is released from AA-treated cells to engage a plasma membrane-associated, pertussis toxin-sensitive, G protein-linked receptor, leading to activation of Erk and adhesion via the Raf-1/Mek signal transduction pathway.
Capodici
C
C
Department of Medicine, New York University School of Medicine, New York 10016, USA.
Pillinger
M H
MH
Han
G
G
Philips
M R
MR
Weissmann
G
G
D001094:Arachidonate 5-Lipoxygenase / Q000502:physiology*; D016718:Arachidonic Acid / Q000494:pharmacology*; D002448:Cell Adhesion; D002449:Cell Aggregation / Q000187:drug effects; D000242:Cyclic AMP / Q000502:physiology; D004789:Enzyme Activation; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D016023:Integrins / Q000502:physiology*; D048728:MAP Kinase Kinase Kinase 1; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D004676:Myelin Basic Protein / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009504:Neutrophils / Q000502:physiology*; D037342:Pertussis Toxin; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D006893:Hydroxyeicosatetraenoic Acids; D016023:Integrins; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins; D010566:Virulence Factors, Bordetella; D016718:Arachidonic Acid; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D000242:Cyclic AMP; D001094:Arachidonate 5-Lipoxygenase; D037342:Pertussis Toxin; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human