Lyn dissociation from phosphorylated Fc epsilon RI subunits: a new regulatory step in the Fc epsilon RI signaling cascade revealed by studies of Fc epsilon RI dimer signaling activity
| Autor: | E, Ortega, M, Lara, I, Lee, C, Santana, A M, Martinez, J R, Pfeiffer, R J, Lee, B S, Wilson, J M, Oliver |
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| Rok vydání: | 1999 |
| Předmět: |
Serotonin
Receptors IgE Cell Membrane Antibodies Monoclonal Antigen-Antibody Complex Inositol 1 4 5-Trisphosphate Phosphoproteins Rats Enzyme Activation Isoenzymes Cross-Linking Reagents src-Family Kinases Leukemia Basophilic Acute Enzyme Induction Tumor Cells Cultured Animals Protein Isoforms Calcium Signaling Phosphorylation Phosphotyrosine Dimerization Cytoskeleton Signal Transduction |
| Zdroj: | Journal of immunology (Baltimore, Md. : 1950). 162(1) |
| ISSN: | 0022-1767 |
| Popis: | Cross-linking the heterotrimeric (alpha beta gamma 2) IgE receptor, Fc epsilon RI, of mast cells activates two tyrosine kinases: Lyn, which phosphorylates beta and gamma subunit immunoreceptor tyrosine-based activation motifs, and Syk, which binds gamma-phospho-immunoreceptor tyrosine-based activation motifs and initiates cellular responses. We studied three Fc epsilon RI-dimerizing mAbs that maintain similar dispersed distributions over the surface of RBL-2H3 mast cells but elicit very different signaling responses. Specifically, mAb H10 receptor dimers induce very little inositol 1,4,5-trisphosphate synthesis, Ca2+ mobilization, secretion, spreading, ruffling, and actin plaque assembly, whereas dimers generated with the other anti-Fc epsilon RI mAbs induce responses that are only modestly lower than that to multivalent Ag. H10 receptor dimers activate Lyn and support Fc epsilon RI beta and gamma subunit phosphorylation but are poor Syk activators compared with Ag and the other anti-Fc epsilon RI mAbs. H10 receptor dimers have two other distinguishing features. First, they induce stable complexes between activated Lyn and receptor subunits. Second, the predominant Lyn-binding phospho-beta isoform found in mAb H10-treated cells is a less tyrosine phosphorylated, more electrophoretically mobile species than the predominant isoform in Ag-treated cells that does not coprecipitate with Lyn. These studies implicate Lyn dissociation from highly phosphorylated receptor subunits as a new regulatory step in the Fc epsilon RI signaling cascade required for Syk activation and signal progression. |
| Databáze: | OpenAIRE |
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