scholarly journals A Composition-Dependent Molecular Clutch Between T Cell Signaling Condensates and Actin

2018 ◽  
Author(s):  
J.A. Ditlev ◽  
A.R. Vega ◽  
D.V. Köster ◽  
X. Su ◽  
T. Tani ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Strong Association ◽  
Adaptor Protein ◽  
T Cell Signaling ◽  
Actin Networks ◽  
Binding Partners ◽  
Surrounding Membrane

AbstractBiomolecular condensates play important roles in eukaryotic cells by concentrating molecules into foci without a surrounding membrane. During T cell activation, biomolecular condensates form at the immunological synapse (IS) through multivalency-driven phase separation of the adaptor protein LAT and its binding partners Grb2, Sos1, SLP-76, Nck and WASP. These condensates move radially at the IS, traversing a radially-oriented and then a concentric actin network. To understand the persistent radial movement, we biochemically reconstituted LAT condensates with mobile actomyosin filaments. We found that basic regions of Nck and N-WASP promote strong association and co-movement of LAT condensates with actin. Condensates lacking these components were instead propelled by steric interactions. In cells, LAT condensates lost Nck while traversing the boundary between the two actin networks, and condensates engineered to constitutively bind actin moved aberrantly. We propose that Nck and WASP form a clutch between LAT condensates and actin, and changes in composition enable condensate movement by distinct actin networks in different regions of the IS.

scholarly journals A composition-dependent molecular clutch between T cell signaling condensates and actin

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jonathon A Ditlev ◽  
Anthony R Vega ◽  
Darius Vasco Köster ◽  
Xiaolei Su ◽  
Tomomi Tani ◽  
...  
Keyword(s):  
Phase Separation ◽  
T Cell ◽  
Cell Signaling ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immunological Synapse ◽  
T Cell Signaling ◽  
Actin Networks ◽  
Compositional Changes

During T cell activation, biomolecular condensates form at the immunological synapse (IS) through multivalency-driven phase separation of LAT, Grb2, Sos1, SLP-76, Nck, and WASP. These condensates move radially at the IS, traversing successive radially-oriented and concentric actin networks. To understand this movement, we biochemically reconstituted LAT condensates with actomyosin filaments. We found that basic regions of Nck and N-WASP/WASP promote association and co-movement of LAT condensates with actin, indicating conversion of weak individual affinities to high collective affinity upon phase separation. Condensates lacking these components were propelled differently, without strong actin adhesion. In cells, LAT condensates lost Nck as radial actin transitioned to the concentric network, and engineered condensates constitutively binding actin moved aberrantly. Our data show that Nck and WASP form a clutch between LAT condensates and actin in vitro and suggest that compositional changes may enable condensate movement by distinct actin networks in different regions of the IS.

The actin cloud induced by LFA-1–mediated outside-in signals lowers the threshold for T-cell activation

Blood ◽  
2006 ◽  
Vol 109 (1) ◽  
pp. 168-175 ◽  
Author(s):  
Jun-ichiro Suzuki ◽  
Sho Yamasaki ◽  
Jennifer Wu ◽  
Gary A. Koretzky ◽  
Takashi Saito
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Adaptor Protein ◽  
Cell Receptor ◽  
Cloud Formation ◽  
Lymphocyte Function ◽  
Tcr Signaling

Abstract The dynamic rearrangement of the actin cytoskeleton plays critical roles in T-cell receptor (TCR) signaling and immunological synapse (IS) formation in T cells. Following actin rearrangement in T cells upon TCR stimulation, we found a unique ring-shaped reorganization of actin called the “actin cloud,” which was specifically induced by outside-in signals through lymphocyte function–associated antigen-1 (LFA-1) engagement. In T-cell–antigen-presenting cell (APC) interactions, the actin cloud is generated in the absence of antigen and localized at the center of the T-cell–APC interface, where it accumulates LFA-1 and tyrosine-phosphorylated proteins. The LFA-1–induced actin cloud formation involves ADAP (adhesion- and degranulation-promoting adaptor protein) phosphorylation, LFA-1/ADAP assembly, and c-Jun N-terminal kinase (JNK) activation, and occurs independent of TCR and its proximal signaling. The formation of the actin cloud lowers the threshold for subsequent T-cell activation. Thus, the actin cloud induced by LFA-1 engagement may serve as a possible platform for LFA-1–mediated costimulatory function for T-cell activation.

scholarly journals Negative Regulation of T Cell Receptor–Lipid Raft Interaction by Cytotoxic T Lymphocyte–associated Antigen 4

2003 ◽  
Vol 197 (1) ◽  
pp. 129-135 ◽  
Author(s):  
Shunsuke Chikuma ◽  
John B. Imboden ◽  
Jeffrey A. Bluestone
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Cytotoxic T Lymphocyte ◽  
Cell Receptor ◽  
T Cell Signaling ◽  
Signaling Complex

Cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) is an essential negative regulator of T cell activation. Recent evidence suggests that CTLA-4 association with the immunological synapse during contact with antigen-presenting cells is important for its inhibitory function. In the present study, we observed a direct interaction of CTLA-4 with the phosphorylated form of T cell receptor (TCR)ζ within the glycolipid-enriched microdomains associated with the T cell signaling complex. In this setting, CTLA-4 regulated the accumulation/retention of TCRζ in the signaling complex, as the lipid raft fractions from CTLA-4KO T cells contained significantly higher amounts of the TCR components when compared with wild-type littermates. In contrast, coligation of CTLA-4 with the TCR during T cell activation selectively decreased the amount of TCRζ that accumulated in the rafts. These results suggest that CTLA-4 functions to regulate T cell signaling by controlling TCR accumulation and/or retention within this a critical component of the immunological synapse.

scholarly journals Disc Large Homolog 1 is critical for early microcluster formation and activation in human T cells

2021 ◽  
Author(s):  
June Guha ◽  
Raj Chari
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Molecular Chaperone ◽  
Cell Activation ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Adaptor Protein ◽  
Tcr Signaling ◽  
Human T Cells

T cell activation by antigen involves multiple sequential steps, including TCR-microcluster (MC) formation, immunological synapse formation and phosphorylation of mediators downstream of the TCR. The adaptor protein Disc Large Homolog 1 (DLG1) is known to regulate proximal TCR signaling and, in turn, T cell activation, acting as a molecular chaperone that organizes specific kinases downstream of antigen recognition. Here, we report using knockdown and knockout studies in human T cells that DLG1 functions even earlier to regulate T cell activation by promoting TCR-MC formation. Moreover, we found that DLG1 can act as a bridge between the TCR-ζ chain and ZAP70 while inhibiting binding of the phosphatase SHP1 to TCR-ζ. Together, these effects drive dysregulation of T cell activation in DLG1-deficient T cells.

scholarly journals Disc Large Homolog 1 Is Critical for Early T Cell Receptor Micro Cluster Formation and Activation in Human T Cells

Vaccines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1446
Author(s):  
June Guha ◽  
Raj Chari
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Signaling ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Cell Activation ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Cell Receptor ◽  
T Cell Signaling

T cell activation by antigen involves multiple sequential steps, including T cell receptor-microcluster TCR-(MC) formation, immunological synapse formation, and phosphorylation of mediators downstream of the TCR. The adaptor protein, Disc Large Homolog 1 (DLG1), is known to regulate proximal TCR signaling and, in turn, T cell activation, acting as a molecular chaperone that organizes specific kinases downstream of antigen recognition. In this study, we used knockdown and knockout technologies in human primary T cells and a human T cell line to demonstrate the role of DLG1 in proximal T cell signaling. High-end confocal microscopy was used for pictorial representation of T cell micro-clusters and colocalization studies. From all these studies, we could demonstrate that DLG1 functions even earlier than immunological synapse formation, to regulate T cell activation by promoting TCR-MC formation. Moreover, we found that DLG1 can act as a bridge between the TCR-ζ chain and ZAP70 while inhibiting binding of the phosphatase SHP1 to TCR-ζ. Together, these effects drive dysregulation of T cell activation in DLG1-deficient T cells. Overall, the activation and survival status of T cell is a critical determinant of effective vaccine response, and DLG1-mediated T cell signaling events can be a driving factor for improving vaccine-designing strategies.

scholarly journals Cooperative Interaction of Nck and Lck Orchestrates Optimal TCR Signaling

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 834
Author(s):  
Frederike A. Hartl ◽  
Jatuporn Ngoenkam ◽  
Esmeralda Beck-Garcia ◽  
Liz Cerqueira ◽  
Piyamaporn Wipa ◽  
...  
Keyword(s):  
T Cell ◽  
Ligand Binding ◽  
T Cell Activation ◽  
Cell Activation ◽  
Adaptor Protein ◽  
Cooperative Interaction ◽  
Tcr Signaling ◽  
Binding Motifs ◽  
Adaptive Immune

The T cell antigen receptor (TCR) is expressed on T cells, which orchestrate adaptive immune responses. It is composed of the ligand-binding clonotypic TCRαβ heterodimer and the non-covalently bound invariant signal-transducing CD3 complex. Among the CD3 subunits, the CD3ε cytoplasmic tail contains binding motifs for the Src family kinase, Lck, and the adaptor protein, Nck. Lck binds to a receptor kinase (RK) motif and Nck binds to a proline-rich sequence (PRS). Both motifs only become accessible upon ligand binding to the TCR and facilitate the recruitment of Lck and Nck independently of phosphorylation of the TCR. Mutations in each of these motifs cause defects in TCR signaling and T cell activation. Here, we investigated the role of Nck in proximal TCR signaling by silencing both Nck isoforms, Nck1 and Nck2. In the absence of Nck, TCR phosphorylation, ZAP70 recruitment, and ZAP70 phosphorylation was impaired. Mechanistically, this is explained by loss of Lck recruitment to the stimulated TCR in cells lacking Nck. Hence, our data uncover a previously unknown cooperative interaction between Lck and Nck to promote optimal TCR signaling.

scholarly journals Nanoconfinement of Microvilli Alters Gene Expression and Boosts T cell Activation

2021 ◽  
Author(s):  
Morteza Aramesh ◽  
Diana Stoycheva ◽  
Ioana Sandu ◽  
Stephan J. Ihle ◽  
Tamara Zund ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
T Cell ◽  
Cell Signaling ◽  
T Cell Activation ◽  
Cell Activation ◽  
Local Environment ◽  
T Cell Signaling ◽  
Sense And Respond ◽  
Altered Gene

T cells sense and respond to their local environment at the nanoscale by forming small actin-rich protrusions, called microvilli, which play critical roles in signaling and antigen recognition, particularly at the interface with the antigen presenting cells. However, the mechanisms by which microvilli contribute to cell signaling and activation is largely unknown. Here, we present a tunable engineered system that promotes microvilli formation and T cell signaling via physical stimuli. We discovered that nanoporous surfaces favored microvilli formation, and markedly altered gene expression in T cells and promoted their activation. Mechanistically, confinement of microvilli inside of nanopores leads to size-dependent sorting of membrane-anchored proteins, specifically segregating CD45 phosphatases and T cell receptors (TCR) from the tip of the protrusions when microvilli are confined in 200 nm pores, but not in 400 nm pores. Consequently, formation of TCR nanoclustered hotspots within 200 nm pores, allows sustained and augmented signaling that prompts T cell activation even in the absence of TCR agonists. The synergistic combination of mechanical and biochemical signals on porous surfaces presents a straightforward strategy to investigate the role of microvilli in T cell signaling as well as to boost T cell activation and expansion for application in the growing field of adoptive immunotherapy.

scholarly journals Retrograde And Anterograde Transport Of LAT-Vesicles During The Immunological Synapse Formation: Defining The Finely-Tuned Mechanism

2020 ◽  
Author(s):  
Juan José Saez ◽  
Stéphanie Dogniaux ◽  
Massiullah Shafaq-Zadah ◽  
Ludger Johannes ◽  
Claire Hivroz ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Retrograde Transport ◽  
Anterograde Transport ◽  
Immune Synapse ◽  
Cellular Context ◽  
Intracellular Compartments

ABSTRACTLAT is an important player of the signaling cascade induced by TCR activation. This adapter molecule is present at the plasma membrane of T lymphocytes and more abundantly in intracellular compartments. Upon T-cell activation the intracellular pool of LAT is recruited to the immune synapse (IS). We previously described two pathways controlling LAT trafficking: retrograde transport from endosomes to the TGN, and anterograde traffic from the Golgi to the IS. We address the specific role of 4 proteins, the GTPase Rab6, the t-SNARE syntaxin-16, the v-SNARE VAMP7 and the golgin GMAP210, in each pathway. Using different methods (endocytosis and Golgi trap assays, confocal and TIRF microscopy, TCR-signalosome pull down) we show that syntaxin-16 is regulating the retrograde transport of LAT whereas VAMP7 is regulating the anterograde transport. Moreover, GMAP210 and Rab6, known to contribute in both pathways, are in our cellular context specifically and respectively involved in anterograde and retrograde transport of LAT. Altogether, our data describe how retrograde and anterograde pathways coordinate LAT enrichment at the IS and point the Golgi as a central hub for the polarized recruitment of LAT to the IS. The role that this finely-tuned transport of signaling molecules plays in T-cell activation is discussed.

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