A requirement for Syk in the activation of the microtubule-associated protein kinase/phospholipase A2 pathway by Fc epsilon R1 is not shared by a G protein-coupled receptor.
Stimulation of the mast cell line, RBL-2H3, with antigen via the tetrameric (alpha beta gamma 2) immunoglobulin E receptor (Fc epsilon R1) leads to the activation of cytosolic phospholipase A2 and the release of arachidonic acid. This pathway is dependent on the activation of the mitogen-activated protein (MAP) kinase. In this paper, we show that the MAP kinase/cytosolic phospholipase A2 pathway is linked to Fc epsilon R1 via the cytosolic tyrosine kinase, Syk, and that the GDP/GTP exchange factor, Vav, might be one candidate for accomplishing this link. Cross-linking of transmembrane chimeras containing the Fc epsilon R1 gamma motif, which is known to activate Syk, results in the tyrosine phosphorylation of Vav, activation of MAP kinase, and release of arachidonic acid. Cross-linking of chimeras containing the Fc epsilon R1 beta motif does not cause these events. Furthermore, stimulation of these events by antigen is enhanced by transient overexpression of a wild-type form of Syk and blocked by overexpression of a dominant negative form of Syk. By contrast, stimulation via the transfected, G protein-coupled, muscarinic m1 receptor is not influenced by either form of Syk and does not result in tyrosine phosphorylation of Vav. These data establish unequivocally that the two types of receptor are independently linked to the two types of receptor are independently linked to the MAP kinase/cytosolic phospholipase A2 pathway and demonstrate the existence of the Fc epsilon R1-Syk-MAP kinase pathway.
Hirasawa
N
N
Laboratory of Molecular Immunology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Scharenberg
A
A
Yamamura
H
H
Beaven
M A
MA
Kinet
J P
JP
D000818:Animals; D000941:Antigens; D016718:Arachidonic Acid / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D018797:Cell Cycle Proteins; D002460:Cell Line; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051567:Proto-Oncogene Proteins c-vav; D051381:Rats; D011940:Receptor Aggregation; D017455:Receptors, IgE / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology*; D011994:Recombinant Proteins; D015398:Signal Transduction; D013552:Swine; D000072377:Syk Kinase; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D000941:Antigens; D018797:Cell Cycle Proteins; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D017455:Receptors, IgE; D011976:Receptors, Muscarinic; D011994:Recombinant Proteins; C496620:Vav1 protein, rat; D019000:Phosphotyrosine; D016718:Arachidonic Acid; D014443:Tyrosine; D002217:Carbachol; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606898:Syk protein, rat; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010741:Phospholipases A; D054467:Phospholipases A2; D019204:GTP-Binding Proteins