FcgammaR receptors activate MAP kinase and up-regulate the cyclooxygenase pathway without increasing arachidonic acid release in monocytic cells.
THP-1 monocytic cells were stimulated with IgG-ovalbumin equivalence immune complexes (IC) and mAb reacting with both FcgammaRI and FcgammaRIIA. All of these stimuli were capable of activating the cells; however, different patterns of response were observed as regards activation of the p42-MAP/ERK kinase, triggering of the NF-kappaB/Rel system, production of chemotactic cytokines, and induction of the expression of cyclooxygenase-2 (COX-2). Activation of p42-MAP/ERK kinase was a constant finding, which occurred regardless of the type of stimulus applied, for instance, homotypic stimulation of a single type of receptor by cross-linking with specific mAb or heterotypic stimulation with both types of antibodies and IC. However, the activation of the MAP/ERK kinase cascade was not connected to the triggering of cytosolic phospholipase A(2) (cPLA(2)) and arachidonic acid (AA) release. The heterotypic stimulation of FcgammaR induced the expression of COX-2 in a time and dose-dependent manner and activated the NF-kappaB system as judged from the degradation of IkappaB-alpha protein. In summary, the present data indicate that activation of the p42-MAP/ERK pathway occurs after cross-linking FcgammaRI and FcgammaRIIA receptors in monocytic cells; however, this is not coupled to the cPLA(2) route, which leads to the release of AA. Noteworthy,heterotypic activation involving combined cross-linking of both FcgammaRI and FcgammaRIIA has a robust effect on the oxidative metabolism of AA by a mechanism involving kappaB-dependent trans-activation of COX-2.
Fernández
Nieves
N
Instituto de Biología y Genética Molecular, Facultad de Medecina, Consejo Superior de Investigaciones Científicas, 47005 Valladolid, Spain.
Renedo
Marta
M
Sánchez Crespo
Mariano
M
D016718:Arachidonic Acid / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D018932:Chemokine CCL2 / Q000096:biosynthesis; D003432:Cross-Linking Reagents; D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D020672:I-kappa B Proteins; D018836:Inflammation Mediators / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics*; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017452:Receptors, IgG / Q000378:metabolism*; D015854:Up-Regulation
D018932:Chemokine CCL2; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D018836:Inflammation Mediators; D007527:Isoenzymes; D008565:Membrane Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D012333:RNA, Messenger; D017452:Receptors, IgG; D000072000:NF-KappaB Inhibitor alpha; D016718:Arachidonic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019950:Mitogen-Activated Protein Kinase 1