ActivatedN-Formyl Peptide Receptor and High-Affinity IgE Receptor Occupy Common Domains for Signaling and Internalization

Abstract

Immune cells display multiple cell surface receptors that integrate signals for survival, proliferation, migration, and degranulation. Here, immunogold labeling is used to map the plasma membrane distributions of two separate receptors, the N-formyl peptide receptor (FPR) and the high-affinity IgE receptor (FRI). We show that the FPR forms signaling clusters in response to monovalent ligand. These domains recruit

Novel Mechanism for FcϵRI-mediated Signal Transducer and Activator of Transcription 5 (STAT5) Tyrosine Phosphorylation and the Selective Influence of STAT5B over Mast Cell Cytokine Production

“…Preparation of Membrane Sheets and Transmission Electron Microscopy-Detailed methods for preparation and immunogold labeling of membrane sheets have been described (17)(18)(19). In brief, BMMCs were primed overnight with DNP-specific IgE, rinsed by centrifugation, and allowed to settle on glass coverslips for 15 min prior to 5-min incubation at 37°C Ϯ DNPcolloidal gold.…”

“…Membrane sheets on grids were then fixed with 2% paraformaldehyde, rinsed, and sequentially stained with primary and secondary antibodies as in Ref. 18. At least two experiments were performed for each condition, for which at least 10 images were acquired on a Hitachi H-7500 transmission electron microscope.…”

Spatio-Temporal Signaling in Mast Cells

“…In a study of RBL-2H3 transfectants stably expressing the FPR, this GPCR was observed to form large clusters in response to addition of monovalent ligand. 40 Ligand-bound FPR cluster rapidly and recruit the heterotrimeric G-protein, Gi. FPR are slowly endocytosed and, by 5 min, most clusters remaining on the surface contain arrestin and very little Gi.…”

The Role of Formylated Peptides and Formyl Peptide Receptor 1 in Governing Neutrophil Function during Acute Inflammation

“…48,49 Meanwhile, receptor internalization predominantly occurs after C-terminal phosphorylation through b-arrestineindependent and noneclathrin-mediated endocytosis. 6,50 Heterologous desensitization of FPR1 can also occur after activation of CD88 [a complement component 5a (C5a) receptor] or chemokine (C-X-C motif) receptor 2 CXCR2; (an IL-8 receptor) due to shared components of intracellular signaling molecules and occurs principally through protein kinase Cemediated pathways. 51 Due to the intracellular signaling hierarchy that exists, however, the capacity for FPR1's heterologous desensitization of other receptors far outstrips their reciprocal ability to inhibit FPR1 function, 52 which was recently highlighted by the observation that the activation of FPR1 in monocytes induces cross-desensitization of CCR1 but not CCR2.…”