Role of Src in the modulation of multiple adaptor proteins in FcalphaRI oxidant signaling.
Cross-linking of Fc receptors for IgA, FcalphaR (CD89), on monocytes/macrophages is known to enhance phagocytic activity and generation of oxygen free radicals. We provide evidence here that the FcalphaR signals through the gamma subunit of FcepsilonRI in U937 cells differentiated with interferon gamma (IFNgamma). Our results provide the first evidence that FcalphaR-mediated signals modulate a multimolecular adaptor protein complex containing Grb2, Shc, SHIP, CrkL, Cbl, and SLP-76. Cross-linking of FcalphaRI using anti-FcalphaRI induces the phosphorylation of the gamma subunit as detected by mobility retardation on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Stimulation of FcalphaRI induced the tyrosine phosphorylation of Shc and increased the association of Grb2 with Shc and CrkL. Grb2 associates constitutively with Sos, and the latter undergoes mobility shift upon FcalphaRI stimulation. The complex adapter proteins, Cbl and SLP-76, are physically associated in myeloid cells and both proteins undergo tyrosine phosphorylation upon FcalphaR stimulation. These data indicate that the stimulation of FcalphaR results in the modulation of adaptor complexes containing tyrosine-phosphorylated Cbl, Shc, SHIP, Grb2, and Crkl. Experiments performed with the Src kinase inhibitor, PP1, provide the first evidence that Src kinase activation is required for FcalphaRI-induced production of superoxide anions and provide insight into the mechanism for FcalphaR-mediated activation of downstream oxidant signaling in myeloid cells.
Park
R K
RK
Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA.
Izadi
K D
KD
Deo
Y M
YM
Durden
D L
DL
D048868:Adaptor Proteins, Signal Transducing; D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000502:physiology*; D002454:Cell Differentiation; D003432:Cross-Linking Reagents / Q000494:pharmacology; D066246:ErbB Receptors / Q000502:physiology; D051380:GRB2 Adaptor Protein; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D046911:Macromolecular Substances; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000502:physiology; D011961:Receptors, Fc / Q000502:physiology*; D011994:Recombinant Proteins; D015398:Signal Transduction; D020298:U937 Cells; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D000906:Antibodies; D015703:Antigens, CD; C082869:CRKL protein; D003432:Cross-Linking Reagents; C036832:Fc(alpha) receptor; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C045281:IgA receptor; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; D011961:Receptors, Fc; D011994:Recombinant Proteins; D007371:Interferon-gamma; D066246:ErbB Receptors