title: The phosphoinositide 3-kinase-dependent activation of Btk is required for optimal eicosanoid production and generation of reactive oxygen species in antigen-stimulated mast cells.
abstract: Activated mast cells are a major source of the eicosanoids PGD(2) and leukotriene C(4) (LTC(4)), which contribute to allergic responses. These eicosanoids are produced following the ERK1/2-dependent activation of cytosolic phospholipase A(2), thus liberating arachidonic acid, which is subsequently metabolized by the actions of 5-lipoxygenase and cyclooxygenase to form LTC(4) and PGD(2), respectively. These pathways also generate reactive oxygen species (ROS), which have been proposed to contribute to FcepsilonRI-mediated signaling in mast cells. In this study, we demonstrate that, in addition to ERK1/2-dependent pathways, ERK1/2-independent pathways also regulate FcepsilonRI-mediated eicosanoid and ROS production in mast cells. A role for the Tec kinase Btk in the ERK1/2-independent regulatory pathway was revealed by the significantly attenuated FcepsilonRI-dependent PGD(2), LTC(4), and ROS production in bone marrow-derived mast cells of Btk(-/-) mice. The FcepsilonRI-dependent activation of Btk and eicosanoid and ROS generation in bone marrow-derived mast cells and human mast cells were similarly blocked by the PI3K inhibitors, Wortmannin and LY294002, indicating that Btk-regulated eicosanoid and ROS production occurs downstream of PI3K. In contrast to ERK1/2, the PI3K/Btk pathway does not regulate cytosolic phospholipase A(2) phosphorylation but rather appears to regulate the generation of ROS, LTC(4), and PGD(2) by contributing to the necessary Ca(2+) signal for the production of these molecules. These data demonstrate that strategies to decrease mast cell production of ROS and eicosanoids would have to target both ERK1/2- and PI3K/Btk-dependent pathways.
authors.affiliation: Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Kuehn
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Swindle
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Michael A
authors.initials: MA
authors.lastname: Beaven
authors.forename: Dean D
authors.initials: DD
authors.lastname: Metcalfe
authors.forename: Alasdair M
authors.initials: AM
authors.lastname: Gilfillan
mesh_terms: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000941:Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D001094:Arachidonate 5-Lipoxygenase / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016718:Arachidonic Acid / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D001854:Bone Marrow Cells / Q000201:enzymology / Q000276:immunology; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006967:Hypersensitivity / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D017997:Leukotriene C4 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D008407:Mast Cells / Q000201:enzymology / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D054510:Phospholipases A2, Cytosolic; D010766:Phosphorylation / Q000187:drug effects; D015230:Prostaglandin D2 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000276:immunology* / Q000378:metabolism; D017455:Receptors, IgE / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000730:Androstadienes; D000941:Antigens; D001094:Arachidonate 5-Lipoxygenase; D016718:Arachidonic Acid; D002867:Chromones; D004791:Enzyme Inhibitors; D017997:Leukotriene C4; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D054510:Phospholipases A2, Cytosolic; D015230:Prostaglandin D2; D011505:Protein-Tyrosine Kinases; D017382:Reactive Oxygen Species; D017455:Receptors, IgE; D000077191:Wortmannin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C000625949:BTK protein, human