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.
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.
Kuehn
Hye Sun
HS
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.
Swindle
Emily J
EJ
Kim
Mi-Sun
MS
Beaven
Michael A
MA
Metcalfe
Dean D
DD
Gilfillan
Alasdair M
AM
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
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