Spatio-Temporal Signaling in Mast Cells

Wilson, Bridget S.; Oliver, Janet M.; Lidke, Diane S.

doi:10.1007/978-1-4419-9533-9_6

Cited by 23 publications

(35 citation statements)

References 88 publications

(111 reference statements)

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“…4 Thus, the computational model provides complementary information and arguably a more precise estimate of the size distribution of receptor aggregates.…”

Section: Results and Discussionmentioning

confidence: 99%

Optimal Aggregation of FcεRI with a Structurally Defined Trivalent Ligand Overrides Negative Regulation Driven by Phosphatases

et al. 2014

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To investigate why responses of mast cells to antigen-induced IgE receptor (FcεRI) aggregation depend nonlinearly on antigen dose, we characterized a new artificial ligand, DF3, through complementary modeling and experimentation. This ligand is a stable trimer of peptides derived from bacteriophage T4 fibritin, each conjugated to a hapten (DNP). We found low and high doses of DF3 at which degranulation of mast cells sensitized with DNP-specific IgE is minimal, but ligand-induced receptor aggregation is comparable to aggregation at an intermediate dose, optimal for degranulation. This finding makes DF3 an ideal reagent for studying the balance of negative and positive signaling in the FcεRI pathway. We find that the lipid phosphatase SHIP and the protein tyrosine phosphatase SHP-1 negatively regulate mast cell degranulation over all doses considered. In contrast, SHP-2 promotes degranulation. With high DF3 doses, relatively rapid recruitment of SHIP to the plasma membrane may explain the reduced degranulation response. Our results demonstrate that optimal secretory responses of mast cells depend on the formation of receptor aggregates that promote sufficient positive signaling by Syk to override phosphatase-mediated negative regulatory signals.

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“…4 Thus, the computational model provides complementary information and arguably a more precise estimate of the size distribution of receptor aggregates.…”

Section: Results and Discussionmentioning

confidence: 99%

Optimal Aggregation of FcεRI with a Structurally Defined Trivalent Ligand Overrides Negative Regulation Driven by Phosphatases

et al. 2014

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“…In animal cells, the presence of so-called nanoclusters of receptor proteins in the PM has been established [16] and is thought to be essential for signal transduction. In addition, internalization of receptors upon ligand-binding- through endocytosis has been reported to take place via specific endosomal locations [17] and by relocalization within the PM itself [18]. …”

Section: Introductionmentioning

confidence: 99%

Visualization of BRI1 and SERK3/BAK1 Nanoclusters in Arabidopsis Roots

et al. 2017

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Brassinosteroids (BRs) are plant hormones that are perceived at the plasma membrane (PM) by the ligand binding receptor BRASSINOSTEROID-INSENSITIVE1 (BRI1) and the co-receptor SOMATIC EMBRYOGENESIS RECEPTOR LIKE KINASE 3/BRI1 ASSOCIATED KINASE 1 (SERK3/BAK1). To visualize BRI1-GFP and SERK3/BAK1-mCherry in the plane of the PM, variable-angle epifluorescence microscopy (VAEM) was employed, which allows selective illumination of a thin surface layer. VAEM revealed an inhomogeneous distribution of BRI1-GFP and SERK3/BAK1-mCherry at the PM, which we attribute to the presence of distinct nanoclusters. Neither the BRI1 nor the SERK3/BAK1 nanocluster density is affected by depletion of endogenous ligands or application of exogenous ligands. To reveal interacting populations of receptor complexes, we utilized selective-surface observation—fluorescence lifetime imaging microscopy (SSO-FLIM) for the detection of Förster resonance energy transfer (FRET). Using this approach, we observed hetero-oligomerisation of BRI1 and SERK3 in the nanoclusters, which did not change upon depletion of endogenous ligand or signal activation. Upon ligand application, however, the number of BRI1-SERK3 /BAK1 hetero-oligomers was reduced, possibly due to endocytosis of active signalling units of BRI1-SERK3/BAK1 residing in the PM. We propose that formation of nanoclusters in the plant PM is subjected to biophysical restraints, while the stoichiometry of receptors inside these nanoclusters is variable and important for signal transduction.

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“…Samples were labeled with anti-FcεRIβ immunogold and imaged by transmission electron microscopy. Images in Figure 3A show that resting receptors are distributed across the cell membrane, alone and in small clusters that likely represent transient co-confinement in membrane domains (50). Figures 3B and 3C show that activation with Pen a 1 (10 or 100 ng/ml) leads an increase in the size of FcεRI clusters on the plasma membrane (arrows).…”

Section: Resultsmentioning

confidence: 99%

Allergen Valency, Dose, and FcεRI Occupancy Set Thresholds for Secretory Responses to Pen a 1 and Motivate Design of Hypoallergens

Mahajan

Youssef

Cleyrat

et al. 2017

The Journal of Immunology

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Antigen-mediated cross-linking of IgE-FcεRI complexes activates mast cells and basophils, initiating the allergic response. Of 34 donors recruited having self-reported shrimp allergy, only 35% had significant levels of shrimp-specific IgE in serum and measurable basophil secretory responses to recombinant Pen a 1 (shrimp tropomyosin). We report that degranulation is linked to the number of FcεRI occupied with allergen-specific IgE, as well as the dose and valency of Pen a 1. Using CRISPR-based gene editing, rat basophilic leukemia (hRBLrαKO) cells were created that exclusively express the hFcεRIα subunit. Pen a 1 specific-IgE (IgEPen a 1) was affinity purified from shrimp positive plasma. Cells primed with a range of IgEPen a 1 and challenged with Pen a 1 show a bell-shaped dose response for secretion, with optimal Pen a 1 doses of 0.1–10 ng/ml. Mathematical modeling provided estimates of receptor aggregation kinetics based upon FcεRI occupancy with IgE and allergen dose. Maximal degranulation was elicited when ~2700 IgE-FcεRI complexes were occupied with specific IgE and challenged with Pen a 1 (IgE epitope valency of 8+), although measurable responses were achieved with only a few hundred FcεRI were occupied. Prolonged periods of pepsin-mediated Pen a 1 proteolysis, which simulates gastric digestion, were required to diminish secretory responses. Recombinant fragments (60–79 amino acids), that together span the entire length of tropomyosin, were weak secretagogues. These fragments have reduced dimerization capacity, compete with intact Pen a 1 for binding to IgE-FcεRI complexes, and represent a starting point for the design of promising hypoallergens for immunotherapy.

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Spatio-Temporal Signaling in Mast Cells

Cited by 23 publications

References 88 publications

Optimal Aggregation of FcεRI with a Structurally Defined Trivalent Ligand Overrides Negative Regulation Driven by Phosphatases

Optimal Aggregation of FcεRI with a Structurally Defined Trivalent Ligand Overrides Negative Regulation Driven by Phosphatases

Visualization of BRI1 and SERK3/BAK1 Nanoclusters in Arabidopsis Roots

Allergen Valency, Dose, and FcεRI Occupancy Set Thresholds for Secretory Responses to Pen a 1 and Motivate Design of Hypoallergens

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