Trivalent Ligands with Rigid DNA Spacers Reveal Structural Requirements For IgE Receptor Signaling in RBL Mast Cells
- 19 October 2007
- journal article
- research article
- Published by American Chemical Society (ACS) in ACS Chemical Biology
- Vol. 2 (10), 674-684
- https://doi.org/10.1021/cb7001472
Abstract
Antigen-mediated cross-linking of IgE bound to its receptor, FcϵRI, stimulates degranulation, phospholipid metabolism, and cytokine production in mast cells and basophils to initiate inflammatory and allergic responses. Previous studies suggested that spatial organization of the clustered receptors affects the assembly of the transmembrane signaling complexes. To investigate systematically the structural constraints in signal initiation, we utilized rigid double-stranded DNA scaffolds to synthesize ligands with tunable lengths. We characterized a series of symmetric trivalent DNA ligands with rigid spacing between 2,4-dinitrophenyl (DNP) haptenic groups in the range of 5–15 nm. These ligands all bind to anti-DNP IgE on RBL mast cells with similar avidity, and they all cross-link IgE–FcϵRI complexes effectively. We observe length-dependent stimulation of tyrosine phosphorylation of FcϵRI β and γ subunits and the adaptor protein LAT: the shortest ligand is ∼5–10-fold more potent than the longest. Stimulated Ca2+ mobilization and degranulation also exhibits kinetics and magnitudes that differ as a function of ligand length. In contrast, tyrosine phosphorylation of phospholipase Cγ1 and consequent Ca2+ release from intracellular stores do not show this dependence on ligand length. Our results with these rigid, DNA-based ligands provide direct support for receptor transphosphorylation as a key step in amplified signaling leading to degranulation, and they further reveal branching of pathways in signaling events.Keywords
This publication has 37 references indexed in Scilit:
- Insights into immunoglobulin E receptor signaling from structurally defined ligandsImmunological Reviews, 2007
- Amplification of CRAC current by STIM1 and CRACM1 (Orai1)Nature, 2006
- Antigen-induced Ca2+ mobilization in RBL-2H3 cells: Role of I(1,4,5)P3 and S1P and necessity of I(1,4,5)P3 productionCell Calcium, 2005
- Lipid segregation and IgE receptor signaling: A decade of progressBiochimica et Biophysica Acta (BBA) - Molecular Cell Research, 2005
- STIM Is a Ca2+ Sensor Essential for Ca2+-Store-Depletion-Triggered Ca2+ InfluxCurrent Biology, 2005
- In situ measurement of degranulation as a biosensor based on RBL-2H3 mast cellsBiosensors and Bioelectronics, 2004
- Signal Transduction Mediated by the T Cell Antigen Receptor: The Role of Adapter ProteinsAnnual Review of Immunology, 2002
- THE HIGH-AFFINITY IgE RECEPTOR (FcεRI): From Physiology to PathologyAnnual Review of Immunology, 1999
- DNA Curvature in Solution Measured by Fluorescence Resonance Energy TransferBiochemistry, 1998
- Altered Patterns of Tyrosine Phosphorylation and Syk Activation for Sterically Restricted Cyclic Dimers of IgE-FcεRIBiochemistry, 1997