scholarly journals Lipid-based, protein-based, and steric interactions synergize to facilitate transmembrane signaling stimulated by antigen-clustering of IgE receptors

2020 ◽  
Author(s):  
Nirmalya Bag ◽  
Alice Wagenknecht-Wiesner ◽  
Allan Lee ◽  
Sophia Shi ◽  
David A. Holowka ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Mast Cells ◽  
Immunoglobulin E ◽  
Tyrosine Phosphatase ◽  
Correlation Spectroscopy ◽  
Current Evidence ◽  
Transmembrane Signaling ◽  
Structural Variants ◽  
Functional Link ◽  
Steric Interactions

ABSTRACTAntigen (Ag) crosslinking of immunoglobulin E-receptor (IgE-FcεRI) complexes in mast cells stimulates transmembrane (TM) signaling, requiring phosphorylation of the clustered FcεRI by lipid-anchored Lyn tyrosine kinase. Previous studies showed that this stimulated coupling between Lyn and FcεRI occurs in liquid ordered (Lo)-like nanodomains of the plasma membrane and that Lyn binds directly to cytosolic segments of FcεRI that it initially phosphorylates for amplified activity. Net phosphorylation above a non-functional threshold is achieved in the stimulated state, but not in the resting state, and current evidence supports the hypothesis that this relies on disruption by Ag-crosslinking of a balance between Lyn and tyrosine phosphatase activities. However, the structural interactions that underlie the stimulation process remain poorly defined. This study evaluates the relative contributions and functional importance of different types of interactions leading to supra-threshold phosphorylation of Ag-crosslinked IgE-FcεRI in live rat basophilic leukemia (RBL) mast cells. Our high-precision diffusion measurements by Imaging Fluorescence Correlation Spectroscopy (ImFCS) on multiple structural variants of Lyn and other lipid-anchored probes confirm subtle, stimulated stabilization of the Lo-like nanodomains and concomitant sharpening of segregation from liquid-disordered (Ld)-like regions. With other structural variants we determine that lipid-based interactions are essential for access by Lyn leading to phosphorylation of and protein-based binding to clustered FcεRI. By contrast, TM tyrosine phosphatase, PTPα, is excluded from these regions by steric repulsion of TM segments and preference for Ld-like regions. Overall, we establish a synergy of lipid-based, protein-based, and steric interactions underlying functional TM signaling in mast cells.SIGNIFICANCE STATEMENTLipid organization of the plasma membrane is known to be important for facilitating protein interactions in transmembrane signaling. However, the orchestration of these interactions in live cells has been elusive. We employed ImFCS to systemically investigate the interplay of lipids and proteins during signaling in mast cells, initiated as phosphorylation of Ag-crosslinked IgE-FcεRI by lipid-anchored Lyn kinase. We find lipid-based interactions are first required for protein-based phosphorylation of the clustered FcεRI within Lo-like nanodomains. Transmembrane phosphatases must be excluded from these regions, and we find this is mediated by their preference for Ld-like regions and by steric exclusion from the clustered FcεRI proteins. ImFCS provides quantitative characterization of the functional link between features of plasma membrane organization and transmembrane signaling.

scholarly journals Lipid-based and protein-based interactions synergize transmembrane signaling stimulated by antigen clustering of IgE receptors

2021 ◽  
Vol 118 (35) ◽  
pp. e2026583118
Author(s):  
Nirmalya Bag ◽  
Alice Wagenknecht-Wiesner ◽  
Allan Lee ◽  
Sophia M. Shi ◽  
David A. Holowka ◽  
...  
Keyword(s):  
Mast Cells ◽  
Immunoglobulin E ◽  
Tyrosine Phosphatase ◽  
Correlation Spectroscopy ◽  
Current Evidence ◽  
Structural Variants ◽  
Fluorescence Correlation ◽  
Ige Receptors ◽  
Liquid Ordered ◽  
Lyn Tyrosine Kinase

Antigen (Ag) crosslinking of immunoglobulin E–receptor (IgE-FcεRI) complexes in mast cells stimulates transmembrane (TM) signaling, requiring phosphorylation of the clustered FcεRI by lipid-anchored Lyn tyrosine kinase. Previous studies showed that this stimulated coupling between Lyn and FcεRI occurs in liquid ordered (Lo)-like nanodomains of the plasma membrane and that Lyn binds directly to cytosolic segments of FcεRI that it initially phosphorylates for amplified activity. Net phosphorylation above a nonfunctional threshold is achieved in the stimulated state but not in the resting state, and current evidence supports the hypothesis that this relies on Ag crosslinking to disrupt a balance between Lyn and tyrosine phosphatase activities. However, the structural interactions that underlie the stimulation process remain poorly defined. This study evaluates the relative contributions and functional importance of different types of interactions leading to suprathreshold phosphorylation of Ag-crosslinked IgE-FcεRI in live rat basophilic leukemia mast cells. Our high-precision diffusion measurements by imaging fluorescence correlation spectroscopy on multiple structural variants of Lyn and other lipid-anchored probes confirm subtle, stimulated stabilization of the Lo-like nanodomains in the membrane inner leaflet and concomitant sharpening of segregation from liquid disordered (Ld)-like regions. With other structural variants, we determine that lipid-based interactions are essential for access by Lyn, leading to phosphorylation of and protein-based binding to clustered FcεRI. By contrast, TM tyrosine phosphatase, PTPα, is excluded from these regions due to its Ld-preference and steric exclusion of TM segments. Overall, we establish a synergy of lipid-based, protein-based, and steric interactions underlying functional TM signaling in mast cells.

scholarly journals Imaging FCS Delineates Subtle Heterogeneity in Plasma Membranes of Resting Mast Cells

2019 ◽  
Author(s):  
Nirmalya Bag ◽  
David A. Holowka ◽  
Barbara A. Baird
Keyword(s):  
Plasma Membrane ◽  
Steady State ◽  
Mast Cells ◽  
Actin Polymerization ◽  
Plasma Membranes ◽  
Correlation Spectroscopy ◽  
Live Cells ◽  
Resting Cells ◽  
Functional Protein ◽  
Diffusion Properties

ABSTRACTA myriad of transient, nanoscopic lipid- and protein-based interactions confer a steady-state organization of plasma membrane in resting cells that is poised to orchestrate assembly of key signaling components upon reception of an extracellular stimulus. Although difficult to observe directly in live cells, these subtle interactions can be discerned by their impact on the diffusion of membrane constituents. Herein, we quantified the diffusion properties of a panel of structurally distinct lipid-anchored and transmembrane (TM) probes in RBL mast cells by multiplexed Imaging Fluorescence Correlation Spectroscopy. We developed a statistical analysis of data combined from many pixels over multiple cells to characterize differences as small as 10% in diffusion coefficients, which reflect differences in underlying interactions. We found that the distinctive diffusion properties of lipid-anchored probes can be explained by their dynamic partitioning into ordered proteo-lipid nanodomains, which encompass a major fraction of the membrane and whose physical properties are influenced by actin polymerization. Effects on diffusion by functional protein modules in both lipid-anchored and TM probes reflect additional complexity in steady-state membrane organization. The contrast we observe between different probes diffusing through the same membrane milieu represent the dynamic resting steady-state, which serves as a baseline for monitoring plasma membrane remodeling that occurs upon stimulation.

scholarly journals Leukocyte common antigen (CD45) is required for immunoglobulin E-mediated degranulation of mast cells.

1994 ◽  
Vol 180 (2) ◽  
pp. 471-476 ◽  
Author(s):  
S A Berger ◽  
T W Mak ◽  
C J Paige
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Immunoglobulin E ◽  
Tyrosine Phosphatase ◽  
Cross Linking ◽  
Ionophore A23187 ◽  
Wild Type ◽  
Ige Receptor ◽  
High Affinity ◽  
Deficient Mice

We demonstrate using primary mast cell cultures derived from wild-type and CD45-deficient mice that mast cell triggering through the high-affinity immunoglobulin E (IgE) receptor requires the cell surface tyrosine phosphatase CD45. Unlike wild-type cells, cross-linking of surface-bound IgE in mast cells deficient in CD45 does not induce degranulation. Degranulation in these mutant cells does occur after treatment with the calcium ionophore A23187 indicating that the degranulation machinery is intact in these cells. We also demonstrate that the tyrosine phosphatase inhibitors orthoVanadate and perVanadate inhibit degranulation in wild-type mast cells, as does cross-linking of CD45 by anti-CD45 antibodies. Finally, we show that CD45-deficient mice are resistant to IgE-dependent systemic anaphylaxis. These results show that, like the T cell receptor and the antigen receptor on B cells, there is an absolute requirement for CD45 in signaling via the high affinity IgE receptor, expanding the number of receptors for which CD45 is an essential component.

scholarly journals Transbilayer Coupling of Lipids in Cells Investigated by Imaging Fluorescence Correlation Spectroscopy

2022 ◽  
Author(s):  
Nirmalya Bag ◽  
Erwin London ◽  
David A Holowka ◽  
Barbara Baird
Keyword(s):  
Plasma Membrane ◽  
Phase Separation ◽  
Fluorescence Correlation Spectroscopy ◽  
Immunoglobulin E ◽  
Correlation Spectroscopy ◽  
Model Systems ◽  
Live Cells ◽  
Membrane Diffusion ◽  
Fluorescence Correlation ◽  
The Impact

Plasma membrane hosts numerous receptors, sensors, and ion channels involved in cellular signaling. Phase separation of the plasma membrane is emerging as a key biophysical regulator of signaling reactions in multiple physiological and pathological contexts. There is much evidence that plasma membrane composition supports the co-existence liquid-ordered (Lo) and liquid-disordered (Ld) phases or domains at physiological conditions. However, this phase/domain separation is nanoscopic and transient in live cells. It is recently proposed that transbilayer coupling between the inner and outer leaflets of the plasma membrane is driven by their asymmetric lipid distribution and by dynamic cytoskeleton-lipid composites that contribute to the formation and transience of Lo/Ld phase separation in live cells. In this Perspective, we highlight new approaches to investigate how transbilayer coupling may influence phase separation. For quantitative evaluation of the impact of these interactions, we introduce an experimental strategy centered around Imaging Fluorescence Correlation Spectroscopy (ImFCS), which measures membrane diffusion with very high precision. To demonstrate this strategy we choose two well-established model systems for transbilayer interactions: crosslinking by multivalent antigen of immunoglobulin E bound to receptor FcεRI, and crosslinking by cholera toxin B of GM1 gangliosides. We discuss emerging methods to systematically perturb membrane lipid composition, particularly exchange of outer leaflet lipids with exogenous lipids using methyl alpha cyclodextrin. These selective perturbations may be quantitatively evaluated with ImFCS and other high-resolution biophysical tools to discover novel principles of lipid-mediated phase separation in live cells in the context of their pathophysiological relevance.

scholarly journals Long acyl chain ceramides govern cholesterol and cytoskeleton dependence of membrane outer leaflet dynamics

2019 ◽  
Author(s):  
Anjali Gupta ◽  
Sneha Muralidharan ◽  
Federico Torta ◽  
Markus R. Wenk ◽  
Thorsten Wohland
Keyword(s):  
Plasma Membrane ◽  
Immunoglobulin E ◽  
Acyl Chain ◽  
Membrane Dynamics ◽  
Correlation Spectroscopy ◽  
Membrane Composition ◽  
Outer Leaflet ◽  
Lipid Mass ◽  
Ceramide Content ◽  
Acyl Chains

ABSTRACTThe cellular plasma membrane composition and organization is crucial for the regulation of biological processes. Based on our earlier work showing that the same lipid probe, DiI, exhibits different dynamics in CHO-K1 and RBL-2H3 cells, we investigate the molecular factors that govern these differences. First, we determined that the cytoskeleton-interacting Immunoglobulin E receptor (FcεRI), which is abundant in RBL-2H3 but not in CHO-K1 cells, is not responsible for the DiI confinement found in RBL-2H3 cells. Second, lipid mass spectrometry of the plasma membrane of the two cells indicated differences in ceramide content, especially with long and very long acyl chains (C16 to C24). We, therefore, measure membrane dynamics by imaging total internal reflection fluorescence correlation spectroscopy in dependence on these ceramides. Our results show that C24 and C16 saturated ceramides uniquely alter the membrane dynamics by promoting the formation of cholesterol-independent domains and by elevating inter-leaflet coupling.

scholarly journals Ubiquitous Overexpression of Chromatin Remodeling Factor SRG3 Exacerbates Atopic Dermatitis in NC/Nga Mice by Enhancing Th2 Immune Responses

2021 ◽  
Vol 22 (4) ◽  
pp. 1553
Author(s):  
Sung Won Lee ◽  
Hyun Jung Park ◽  
Jungmin Jeon ◽  
Yun Hoo Park ◽  
Tae-Cheol Kim ◽  
...  
Keyword(s):  
Atopic Dermatitis ◽  
Mast Cells ◽  
Immune Responses ◽  
Chromatin Remodeling ◽  
Skin Diseases ◽  
Immunoglobulin E ◽  
Critical Role ◽  
Interleukin 4 ◽  
Inflammatory Skin Diseases ◽  
Immune Disorder

The SWItch (SWI)3-related gene (SRG3) product, a SWI/Sucrose Non-Fermenting (SNF) chromatin remodeling subunit, plays a critical role in regulating immune responses. We have previously shown that ubiquitous SRG3 overexpression attenuates the progression of Th1/Th17-mediated experimental autoimmune encephalomyelitis. However, it is unclear whether SRG3 overexpression can affect the pathogenesis of inflammatory skin diseases such as atopic dermatitis (AD), a Th2-type immune disorder. Thus, to elucidate the effects of SRG3 overexpression in AD development, we bred NC/Nga (NC) mice with transgenic mice where SRG3 expression is driven by the β-actin promoter (SRG3β-actin mice). We found that SRG3β-actin NC mice exhibit increased AD development (e.g., a higher clinical score, immunoglobulin E (IgE) hyperproduction, and an increased number of infiltrated mast cells and basophils in skin lesions) compared with wild-type NC mice. Moreover, the severity of AD pathogenesis in SRG3β-actin NC mice correlated with expansion of interleukin 4 (IL4)-producing basophils and mast cells, and M2 macrophages. Furthermore, this accelerated AD development is strongly associated with Treg cell suppression. Collectively, our results have identified that modulation of SRG3 function can be applied as one of the options to control AD pathogenesis.

Mast Cell Heterogeneity in Human Lung Tissue

1989 ◽  
Vol 77 (3) ◽  
pp. 297-304 ◽  
Author(s):  
F. J. Van Overveld ◽  
L. A. M. J. Houben ◽  
F. E. M. Schmitz du Moulin ◽  
P. L. B. Bruijnzeel ◽  
J. A. M. Raaijmakers ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Alcian Blue ◽  
Lung Tissue ◽  
Human Lung ◽  
Immunoglobulin E ◽  
Prostaglandin D2 ◽  
Leukotriene C4 ◽  
Human Lung Tissue ◽  
No Release

1. In this study mast cells were found to comprise 2.1% of total cells recovered by enzymatic digestion of human lung tissue. 2. This mast cell population consisted of 79% formalin-sensitive, Alcian Blue-positive mast cells and 21% formalin-insensitive, Alcian Blue-positive mast cells. 3. By the use of centrifugal elutriation and subsequent Percoll gradient centrifugation, separate mixed cell populations could be obtained in which the mast cell constituents were either of the formalin-sensitive or -insensitive type. 4. Cell suspensions in which formalin-sensitive cells comprised 97% of mast cells contained approximately 1.34 pg of histamine per mast cell, whereas in preparations in which mast cells were 84% formalin-resistant the histamine content was approximately 4.17 pg of histamine per mast cell. 5. The histamine release upon anti-immunoglobulin E challenge of formalin-sensitive mast cells was greater than the release by formalin-insensitive mast cells. 6. After challenge with opsonized zymosan, only formalin-sensitive mast cells were able to release histamine. 7. Leukotriene C4 release was observed when formalin-sensitive mast cells were challenged with antiimmunoglobulin E. Formalin-insensitive mast cells showed no release of leukotriene C4. 8. Prostaglandin D2 release was observed when formalin-insensitive mast cells were challenged with antiimmunoglobulin E. Formalin-sensitive mast cells showed no release of prostaglandin D2.

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