scholarly journals Calcium influx through CRAC channels controls actin organization and dynamics at the immune synapse

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Catherine A Hartzell ◽  
Katarzyna I Jankowska ◽  
Janis K Burkhardt ◽  
Richard S Lewis
Keyword(s):  
Actin Polymerization ◽  
Calcium Influx ◽  
Cell Receptor ◽  
Feedback Loops ◽  
Tcr Signaling ◽  
Immune Synapse ◽  
Actin Organization ◽  
Crac Channels ◽  
Crac Channel ◽  
Antigen Presenting

T cell receptor (TCR) engagement opens Ca2+ release-activated Ca2+ (CRAC) channels and triggers formation of an immune synapse between T cells and antigen-presenting cells. At the synapse, actin reorganizes into a concentric lamellipod and lamella with retrograde actin flow that helps regulate the intensity and duration of TCR signaling. We find that Ca2+ influx is required to drive actin organization and dynamics at the synapse. Calcium acts by promoting actin depolymerization and localizing actin polymerization and the actin nucleation promotion factor WAVE2 to the periphery of the lamellipod while suppressing polymerization elsewhere. Ca2+-dependent retrograde actin flow corrals ER tubule extensions and STIM1/Orai1 complexes to the synapse center, creating a self-organizing process for CRAC channel localization. Our results demonstrate a new role for Ca2+ as a critical regulator of actin organization and dynamics at the synapse, and reveal potential feedback loops through which Ca2+ influx may modulate TCR signaling.

scholarly journals mDia1/3-dependent actin polymerization spatiotemporally controls LAT phosphorylation by Zap70 at the immune synapse

2020 ◽  
Vol 6 (1) ◽  
pp. eaay2432 ◽  
Author(s):  
D. Thumkeo ◽  
Y. Katsura ◽  
Y. Nishimura ◽  
P. Kanchanawong ◽  
K. Tohyama ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Transmembrane Protein ◽  
Three Dimensional ◽  
Cell Receptor ◽  
Filamentous Actin ◽  
Tcr Signaling ◽  
Immune Synapse ◽  
Physiological Importance ◽  
Resolution Imaging ◽  
Tcr Activation

The mechanism by which the cytosolic protein Zap70 physically interacts with and phosphorylates its substrate, the transmembrane protein LAT, upon T cell receptor (TCR) stimulation remains largely obscure. In this study, we found that the pharmacological inhibition of formins, a major class of actin nucleators, suppressed LAT phosphorylation by Zap70, despite TCR stimulation–dependent phosphorylation of Zap70 remaining intact. High-resolution imaging and three-dimensional image reconstruction revealed that localization of phosphorylated Zap70 to the immune synapse (IS) and subsequent LAT phosphorylation are critically dependent on formin-mediated actin polymerization. Using knockout mice, we identify mDia1 and mDia3, which are highly expressed in T cells and which localize to the IS upon TCR activation, as the critical formins mediating this process. Our findings therefore describe previously unsuspected roles for mDia1 and mDia3 in the spatiotemporal control of Zap70-dependent LAT phosphorylation at the IS through regulation of filamentous actin, and underscore their physiological importance in TCR signaling.

scholarly journals Author response: Calcium influx through CRAC channels controls actin organization and dynamics at the immune synapse

2016 ◽  
Author(s):  
Catherine A Hartzell ◽  
Katarzyna I Jankowska ◽  
Janis K Burkhardt ◽  
Richard S Lewis
Keyword(s):  
Calcium Influx ◽  
Author Response ◽  
Immune Synapse ◽  
Actin Organization ◽  
Crac Channels

scholarly journals Ca2+/Calmodulin-Dependent Protein Kinase II Is a Modulator of CARMA1-Mediated NF-κB Activation

2006 ◽  
Vol 26 (14) ◽  
pp. 5497-5508 ◽  
Author(s):  
Kazuhiro Ishiguro ◽  
Todd Green ◽  
Joseph Rapley ◽  
Heather Wachtel ◽  
Cosmas Giallourakis ◽  
...  
Keyword(s):  
T Cell ◽  
Protein Kinase ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Dependent Protein Kinase ◽  
Immune Synapse ◽  
Protein Kinase Ii ◽  
Dependent Protein

ABSTRACT CARMA1 is a central regulator of NF-κB activation in lymphocytes. CARMA1 and Bcl10 functionally interact and control NF-κB signaling downstream of the T-cell receptor (TCR). Computational analysis of expression neighborhoods of CARMA1-Bcl10MALT 1 for enrichment in kinases identified calmodulin-dependent protein kinase II (CaMKII) as an important component of this pathway. Here we report that Ca2+/CaMKII is redistributed to the immune synapse following T-cell activation and that CaMKII is critical for NF-κB activation induced by TCR stimulation. Furthermore, CaMKII enhances CARMA1-induced NF-κB activation. Moreover, we have shown that CaMKII phosphorylates CARMA1 on Ser109 and that the phosphorylation facilitates the interaction between CARMA1 and Bcl10. These results provide a novel function for CaMKII in TCR signaling and CARMA1-induced NF-κB activation.

scholarly journals Fyn-Binding Protein (Fyb)/Slp-76–Associated Protein (Slap), Ena/Vasodilator-Stimulated Phosphoprotein (Vasp) Proteins and the Arp2/3 Complex Link T Cell Receptor (Tcr) Signaling to the Actin Cytoskeleton

2000 ◽  
Vol 149 (1) ◽  
pp. 181-194 ◽  
Author(s):  
Matthias Krause ◽  
Antonio S. Sechi ◽  
Marlies Konradt ◽  
David Monner ◽  
Frank B. Gertler ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Actin Cytoskeleton ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Signaling ◽  
Tcr Signaling ◽  
Activated T Cells ◽  
Antigen Presenting ◽  
Syndrome Protein

T cell receptor (TCR)-driven activation of helper T cells induces a rapid polarization of their cytoskeleton towards bound antigen presenting cells (APCs). We have identified the Fyn- and SLP-76–associated protein Fyb/SLAP as a new ligand for Ena/ vasodilator-stimulated phosphoprotein (VASP) homology 1 (EVH1) domains. Upon TCR engagement, Fyb/SLAP localizes at the interface between T cells and anti-CD3–coated beads, where Evl, a member of the Ena/VASP family, Wiskott-Aldrich syndrome protein (WASP) and the Arp2/3 complex are also found. In addition, Fyb/SLAP is restricted to lamellipodia of spreading platelets. In activated T cells, Fyb/SLAP associates with Ena/VASP family proteins and is present within biochemical complexes containing WASP, Nck, and SLP-76. Inhibition of binding between Fyb/SLAP and Ena/VASP proteins or WASP and the Arp2/3 complex impairs TCR-dependent actin rearrangement, suggesting that these interactions play a key role in linking T cell signaling to remodeling of the actin cytoskeleton.

scholarly journals Agent-Based Modeling of T Cell Receptor Cooperativity

2020 ◽  
Vol 21 (18) ◽  
pp. 6473
Author(s):  
Anastasios Siokis ◽  
Philippe A. Robert ◽  
Michael Meyer-Hermann
Keyword(s):  
T Cell ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Cell Receptor ◽  
Agent Based Model ◽  
Tcr Signaling ◽  
Immune Synapse ◽  
Agent Based ◽  
Affinity Modulation ◽  
Antigen Peptide

Immunological synapse (IS) formation is a key event during antigen recognition by T cells. Recent experimental evidence suggests that the affinity between T cell receptors (TCRs) and antigen is actively modulated during the early steps of TCR signaling. In this work, we used an agent-based model to study possible mechanisms for affinity modulation during IS formation. We show that, without any specific active mechanism, the observed affinity between receptors and ligands evolves over time and depends on the density of ligands of the antigen peptide presented by major histocompatibility complexes (pMHC) and TCR molecules. A comparison between the presence or absence of TCR–pMHC centrally directed flow due to F-actin coupling suggests that centripetal transport is a potential mechanism for affinity modulation. The model further suggests that the time point of affinity measurement during immune synapse formation is critical. Finally, a mathematical model of F-actin foci formation incorporated in the agent-based model shows that TCR affinity can potentially be actively modulated by positive/negative feedback of the F-actin foci on the TCR-pMHC association rate kon.

scholarly journals Formin-generated actomyosin arcs propel T cell receptor microcluster movement at the immune synapse

2016 ◽  
Vol 215 (3) ◽  
pp. 383-399 ◽  
Author(s):  
Sricharan Murugesan ◽  
Jinsung Hong ◽  
Jason Yi ◽  
Dong Li ◽  
Jordan R. Beach ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Immunological Synapse ◽  
Three Dimensional ◽  
Cell Receptor ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Tcr Signaling ◽  
Immune Synapse ◽  
Distal Edge

Actin assembly and inward flow in the plane of the immunological synapse (IS) drives the centralization of T cell receptor microclusters (TCR MCs) and the integrin leukocyte functional antigen 1 (LFA-1). Using structured-illumination microscopy (SIM), we show that actin arcs populating the medial, lamella-like region of the IS arise from linear actin filaments generated by one or more formins present at the IS distal edge. After traversing the outer, Arp2/3-generated, lamellipodia-like region of the IS, these linear filaments are organized by myosin II into antiparallel concentric arcs. Three-dimensional SIM shows that active LFA-1 often aligns with arcs, whereas TCR MCs commonly reside between arcs, and total internal reflection fluorescence SIM shows TCR MCs being swept inward by arcs. Consistently, disrupting actin arc formation via formin inhibition results in less centralized TCR MCs, missegregated integrin clusters, decreased T–B cell adhesion, and diminished TCR signaling. Together, our results define the origin, organization, and functional significance of a major actomyosin contractile structure at the IS that directly propels TCR MC transport.

scholarly journals RIAM Links the ADAP/SKAP-55 Signaling Module to Rap1, Facilitating T-Cell-Receptor-Mediated Integrin Activation

2007 ◽  
Vol 27 (11) ◽  
pp. 4070-4081 ◽  
Author(s):  
Gaël Ménasché ◽  
Stefanie Kliche ◽  
Emily J. H. Chen ◽  
Theresia E. B. Stradal ◽  
Burkhart Schraven ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Small Gtpase ◽  
Adapter Proteins ◽  
Adapter Protein ◽  
Integrin Activation ◽  
Tcr Signaling ◽  
Antigen Presenting

ABSTRACT One outcome of T-cell receptor (TCR) signaling is increased affinity and avidity of integrins for their ligands. This occurs through a process known as inside-out signaling, which has been shown to require several molecular components including the adapter proteins ADAP (adhesion and degranulation-promoting adapter protein) and SKAP-55 (55-kDa src kinase-associated phosphoprotein) and the small GTPase Rap1. Herein, we provide evidence linking ADAP and SKAP-55 to RIAM, a recently described adapter protein that binds selectively to active Rap1. We identified RIAM as a key component linking the ADAP/SKAP-55 module to the small GTPase Rap1, facilitating TCR-mediated integrin activation. We show that RIAM constitutively interacts with SKAP-55 in both a heterologous transfection system and primary T cells and map the region essential for this interaction. Additionally, we find that the SKAP-55/RIAM complex is essential both for TCR-mediated adhesion and for efficient conjugate formation between T cells and antigen-presenting cells. Mechanistic studies revealed that the ADAP/SKAP-55 module relocalized RIAM and Rap1 to the plasma membrane following TCR activation to facilitate integrin activation. These results describe for the first time a link between ADAP/SKAP-55 and the Rap1/RIAM complex and provide a potential new mechanism for TCR-mediated integrin activation.

scholarly journals The Swing of Lipids at Peroxisomes and Endolysosomes in T Cell Activation

2020 ◽  
Vol 21 (8) ◽  
pp. 2859
Author(s):  
Sara G. Dosil ◽  
Amelia Rojas-Gomez ◽  
Francisco Sánchez-Madrid ◽  
Noa B. Martín-Cófreces
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Synapse Formation ◽  
Cell Receptor ◽  
Metabolic Reprogramming ◽  
Mitochondrial Activity ◽  
Oxygen Species ◽  
Immune Synapse ◽  
Antigen Presenting

The immune synapse (IS) is a well-known intercellular communication platform, organized at the interphase between the antigen presenting cell (APC) and the T cell. After T cell receptor (TCR) stimulation, signaling from plasma membrane proteins and lipids is amplified by molecules and downstream pathways for full synapse formation and maintenance. This secondary signaling event relies on intracellular reorganization at the IS, involving the cytoskeleton and components of the secretory/recycling machinery, such as the Golgi apparatus and the endolysosomal system (ELS). T cell activation triggers a metabolic reprogramming that involves the synthesis of lipids, which act as signaling mediators, and an increase of mitochondrial activity. Then, this mitochondrial activity results in elevated reactive oxygen species (ROS) production that may lead to cytotoxicity. The regulation of ROS levels requires the concerted action of mitochondria and peroxisomes. In this review, we analyze this reprogramming and the signaling implications of endolysosomal, mitochondrial, peroxisomal, and lipidic systems in T cell activation.

scholarly journals Target-Cell Contact Activates a Highly Selective Capacitative Calcium Entry Pathway in Cytotoxic T Lymphocytes

2000 ◽  
Vol 148 (3) ◽  
pp. 603-614 ◽  
Author(s):  
Adam Zweifach
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
T Cell Receptor ◽  
Target Cell ◽  
Calcium Influx ◽  
Cytotoxic T Cells ◽  
Cell Receptor ◽  
Cell Contact ◽  
Crac Channels

Calcium influx is critical for T cell activation. Evidence has been presented that T cell receptor–stimulated calcium influx in helper T lymphocytes occurs via channels activated as a consequence of depletion of intracellular calcium stores, a mechanism known as capacitative Ca2+ entry (CCE). However, two key questions have not been addressed. First, the mechanism of calcium influx in cytotoxic T cells has not been examined. While the T cell receptor–mediated early signals in helper and cytotoxic T cells are similar, the physiology of the cells is strikingly different, raising the possibility that the mechanism of calcium influx is also different. Second, contact of T cells with antigen-presenting cells or targets involves a host of intercellular interactions in addition to those between antigen–MHC and the T cell receptor. The possibility that calcium influx pathways in addition to those activated via the T cell receptor may be activated by contact with relevant cells has not been addressed. We have used imaging techniques to show that target-cell–stimulated calcium influx in CTLs occurs primarily through CCE. We investigated the permeability of the CTL influx pathway for divalent cations, and compared it to the permeability of CCE in Jurkat human leukemic T cells. CCE in CTLs shows a similar ability to discriminate between calcium, barium, and strontium as CCE in Jurkat human leukemic T lymphocytes, where CCE is likely to mediated by Ca2+ release–activated Ca2+ current (CRAC) channels, suggesting that CRAC channels also underlie CCE in CTLs. These results are the first determination of the mechanism of calcium influx in cytotoxic T cells and the first demonstration that cell contact–mediated calcium signals in T cells occur via depletion-activated channels.

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