236 T-Cell Receptor (TCR) Activation Mediates Efficient and Sustained HIV Transcriptional Elongation and Initiation through Multiple Signal Pathways

2009 ◽  
Vol 51 ◽  
pp. 1
Author(s):  
Joseph F Hokello
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Signal Pathways ◽  
Transcriptional Elongation ◽  
Multiple Signal ◽  
Tcr Activation

scholarly journals Structural variability and concerted motions of the T cell receptor – CD3 complex

2021 ◽  
Author(s):  
Prithvi R. Pandey ◽  
Bartosz Różycki ◽  
Reinhard Lipowsky ◽  
Thomas R. Weikl
Keyword(s):  
Molecular Dynamics ◽  
T Cell ◽  
Molecular Dynamics Simulations ◽  
T Cell Receptor ◽  
Tilt Angle ◽  
Structural Changes ◽  
Cell Receptor ◽  
Transmembrane Helices ◽  
Dynamics Simulations ◽  
Tcr Activation

AbstractWe investigate the structural and orientational variability of the membrane-embedded T cell receptor (TCR) – CD3 complex in extensive atomistic molecular dynamics simulations based on the recent cryo-EM structure determined by Dong et al. (2019). We find that the TCR extracellular (EC) domain is highly variable in its orientation by attaining tilt angles relative to the membrane normal that range from 15° to 55°. The tilt angle of the TCR EC domain is both coupled to a rotation of the domain and to characteristic changes throughout the TCR – CD3 complex, in particular in the EC interactions of the Cβ FG loop of the TCR, as well as in the orientation of transmembrane helices. The concerted motions of the membrane-embedded TCR – CD3 complex revealed in our simulations provide atomistic insights for force-based models of TCR activation, which involve such structural changes in response to tilt-inducing forces on antigen-bound TCRs.

scholarly journals The structural basis of T-cell receptor (TCR) activation: An enduring enigma

2019 ◽  
Vol 295 (4) ◽  
pp. 914-925 ◽  
Author(s):  
Roy A. Mariuzza ◽  
Pragati Agnihotri ◽  
John Orban
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Intracellular Signaling ◽  
Rational Design ◽  
Cell Receptor ◽  
Structural Basis ◽  
Specific Information ◽  
Antigenic Peptides ◽  
Tcr Activation

T cells are critical for protective immune responses to pathogens and tumors. The T-cell receptor (TCR)–CD3 complex is composed of a diverse αβ TCR heterodimer noncovalently associated with the invariant CD3 dimers CD3ϵγ, CD3ϵδ, and CD3ζζ. The TCR mediates recognition of antigenic peptides bound to MHC molecules (pMHC), whereas the CD3 molecules transduce activation signals to the T cell. Whereas much is known about downstream T-cell signaling pathways, the mechanism whereby TCR engagement by pMHC is first communicated to the CD3 signaling apparatus, a process termed early T-cell activation, remains largely a mystery. In this review, we examine the molecular basis for TCR activation in light of the recently determined cryoEM structure of a complete TCR–CD3 complex. This structure provides an unprecedented opportunity to assess various signaling models that have been proposed for the TCR. We review evidence from single-molecule and structural studies for force-induced conformational changes in the TCR–CD3 complex, for dynamically-driven TCR allostery, and for pMHC-induced structural changes in the transmembrane and cytoplasmic regions of CD3 subunits. We identify major knowledge gaps that must be filled in order to arrive at a comprehensive model of TCR activation that explains, at the molecular level, how pMHC-specific information is transmitted across the T-cell membrane to initiate intracellular signaling. An in-depth understanding of this process will accelerate the rational design of immunotherapeutic agents targeting the TCR–CD3 complex.

scholarly journals Estrogen receptor beta signaling in CD8+ T cells boosts T cell receptor activation and antitumor immunity through a phosphotyrosine switch

2021 ◽  
Vol 9 (1) ◽  
pp. e001932
Author(s):  
Bin Yuan ◽  
Curtis A Clark ◽  
Bogang Wu ◽  
Jing Yang ◽  
Justin M Drerup ◽  
...  
Keyword(s):  
T Cells ◽  
Estrogen Receptor ◽  
T Cell ◽  
Tumor Growth ◽  
T Cell Receptor ◽  
Antitumor Immunity ◽  
Cell Receptor ◽  
Signaling Cascade ◽  
Tcr Activation

BackgroundThe non-overlapping functions of the two estrogen receptor subtypes, ERα (Estrogen Receptor α)and ERβ (Estrogen Receptor β), in tumor cells have been studied extensively. However, their counterparts in host cells is vastly underinterrogated. Even less is known about how ERα and ERβ activities are regulated in a subtype-specific manner. We previously identified a phosphotyrosine residue (pY36) of human ERβ that is important for tumor ERβ to inhibit growth of breast cancer cells in vitro and in vivo. A role of this ERβ phosphotyrosine switch in regulating host ERβ remains unclear.Conventional gene editing was used to mutate the corresponding tyrosine residue of endogenous mouse ERβ (Y55F) in mouse embryonic stem cells. The derived homozygous mutant Esr2Y55F/Y55F mouse strain and its wild-type (WT) counterpart were compared in various transplant tumor models for their ability to support tumor growth. In addition, flow cytometry-based immunophenotyping was carried out to assess antitumor immunity of WT and mutant hosts. Adoptive transfer of bone marrow and purified CD8+ T cells were performed to identify the host cell type that harbors ERβ-dependent antitumor function. Furthermore, cell signaling assays were conducted to compare T cell receptor (TCR)-initiated signaling cascade in CD8+ T cells of WT and mutant mice. Lastly, the ERβ-selective agonist S-equol was evaluated for its efficacy to boost immune checkpoint blockade (ICB)-based anticancer immunotherapy.Disabling the ERβ-specific phosphotyrosine switch in tumor-bearing hosts exacerbates tumor growth. Further, a cell-autonomous ERβ function was defined in CD8+ effector T cells. Mechanistically, TCR activation triggers ERβ phosphorylation, which in turn augments the downstream TCR signaling cascade via a non-genomic action of ERβ. S-equol facilitates TCR activation that stimulates the ERβ phosphotyrosine switch and boosts anti-PD-1 (Programmed cell death protein 1) ICB immunotherapy.Our mouse genetic study clearly demonstrates a role of the ERβ phosphotyrosine switch in regulating ERβ-dependent antitumor immunity in CD8+ T cells. Our findings support the development of ERβ agonists including S-equol in combination with ICB immunotherapy for cancer treatment.

scholarly journals PTPN22 interacts with EB1 to regulate T cell receptor signaling

2018 ◽  
Author(s):  
Xiaonan Zhang ◽  
Bin Bai ◽  
Tao Wang ◽  
Jiahui Zhao ◽  
Na Zhang ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Signaling ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Phosphorylation Site ◽  
Cell Receptor ◽  
Negative Regulator ◽  
Signal Pathways ◽  
T Cell Signaling ◽  
Activation Markers

AbstractPTPN22 has been reported as an important negative regulator of T cell signaling. Here we identified EB1 as an associated protein of PTPN22 via 2-hybrid and mass spectrometry screening.Recently the phosphorylation of EB1 has been proved in the regulation of T cell receptor (TCR) mediated signaling pathway. Our results shown that PTPN22 interacted with EB1 through the P1 domain of PTPN22, and regulated the Y247 phosphorylation site of EB1. The subsequent results suggest that PTPN22 interacts with EB1 and regulate the phosphorylation of EB1, which results in the regulation of the expression of T cell activation markers of CD25 and CD69, and the phosphorylation levels of the T cell signaling molecules, such as ZAP-70, LAT and Erk, ultimately resulting in NFAT transcription factors entering the nucleus and regulating the secretion of cytokine IL-2. This newly identified interaction between PTPN22 and EB1 may play an important role in TCR signal pathways.

scholarly journals Cholera toxin discriminates between T helper 1 and 2 cells in T cell receptor-mediated activation: role of cAMP in T cell proliferation.

1990 ◽  
Vol 172 (1) ◽  
pp. 95-103 ◽  
Author(s):  
E Muñoz ◽  
A M Zubiaga ◽  
M Merrow ◽  
N P Sauter ◽  
B T Huber
Keyword(s):  
T Cell ◽  
Cholera Toxin ◽  
T Cell Receptor ◽  
Present Report ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Th2 Cells ◽  
Signal Pathways ◽  
Intracellular Camp ◽  
T Helper

CD4+ T helper (Th) clones can be divided into interleukin 2 (IL-2)-secreting Th1 and IL-4-secreting Th2 cells. We show in the present report that these two Th subsets have different activation requirements for lymphokine production and proliferation: namely, cholera toxin (CT) as well as forskolin inhibit T cell receptor (TCR)-mediated IL-2 production and proliferation in Th1 cells, while the same reagents fail to block IL-4 production and proliferation in Th2 cells. In addition, CT and forskolin differentially influence the proto-oncogene mRNA expression in Th1 vs. Th2 cells after stimulation with Con A. Since both reagents lead to elevated levels of intracellular cAMP, it is likely that Th1 and Th2 cells differ in their sensitivity to an increase in cAMP. Our results indicate that the two Th subsets use different transmission signal pathways upon TCR-mediated activation.

scholarly journals Inhibition of T Cell Receptor Activation by Semi-Synthetic Sesquiterpene Lactone Derivatives and Molecular Modeling of Their Interaction with Glutathione and Tyrosine Kinase ZAP-70

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 350 ◽  
Author(s):  
Andrei Khlebnikov ◽  
Igor Schepetkin ◽  
Anarkul Kishkentaeva ◽  
Zhanar Shaimerdenova ◽  
Gayane Atazhanova ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tyrosine Kinase ◽  
T Cell Receptor ◽  
Sesquiterpene Lactones ◽  
Cell Receptor ◽  
Receptor Activation ◽  
Tcr Signaling ◽  
Jurkat T Cells ◽  
Tcr Activation

A variety of natural compounds have been shown to modulate T cell receptor (TCR) activation, including natural sesquiterpene lactones (SLs). In the present studies, we evaluated the biological activity of 11 novel semi-synthetic SLs to determine their ability to modulate TCR activation. Of these compounds, α -epoxyarglabin, cytisinyl epoxyarglabin, 1 β ,10 α -epoxyargolide, and chloroacetate grosheimin inhibited anti-CD3-induced Ca2+ mobilization and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in Jurkat T cells. We also found that the active SLs depleted intracellular glutathione (GSH) in Jurkat T cells, supporting their reactivity towards thiol groups. Because the zeta-chain associated tyrosine kinase 70 kDa (ZAP-70) is essential for TCR signaling and contains a tandem SH2 region that is highly enriched with multiple cysteines, we performed molecular docking of natural SLs and their semi-synthetic derivatives into the ZAP-70 binding site. The docking showed that the distance between the carbon atom of the exocyclic methylene group and the sulfur atom in Cys39 of the ZAP-70 tandem SH2 module was 3.04–5.3 Å for active compounds. Furthermore, the natural SLs and their derivatives could be differentiated by their ability to react with the Cys39 SH-group. We suggest that natural and/or semi-synthetic SLs with an α -methylene- γ -lactone moiety can specifically target GSH and the kinase site of ZAP-70 and inhibit the initial phases of TCR activation.

scholarly journals Bcl-2 differentially regulates Ca2+ signals according to the strength of T cell receptor activation

2006 ◽  
Vol 172 (1) ◽  
pp. 127-137 ◽  
Author(s):  
Fei Zhong ◽  
Michael C. Davis ◽  
Karen S. McColl ◽  
Clark W. Distelhorst
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Receptor Activation ◽  
Receptor Subtypes ◽  
Activated T Cells ◽  
High Concentrations ◽  
Tcr Activation ◽  
Insp3 Receptor

To investigate the effect of Bcl-2 on Ca2+ signaling in T cells, we continuously monitored Ca2+ concentration in Bcl-2–positive and –negative clones of the WEHI7.2 T cell line after T cell receptor (TCR) activation by anti-CD3 antibody. In Bcl-2–negative cells, high concentrations of anti-CD3 antibody induced a transient Ca2+ elevation, triggering apoptosis. In contrast, low concentrations of anti-CD3 antibody induced Ca2+ oscillations, activating the nuclear factor of activated T cells (NFAT), a prosurvival transcription factor. Bcl-2 blocked the transient Ca2+ elevation induced by high anti-CD3, thereby inhibiting apoptosis, but did not inhibit Ca2+ oscillations and NFAT activation induced by low anti-CD3. Reduction in the level of all three inositol 1,4,5-trisphosphate (InsP3) receptor subtypes by small interfering RNA inhibited the Ca2+ elevation induced by high but not low anti-CD3, suggesting that Ca2+ responses to high and low anti-CD3 may have different requirements for the InsP3 receptor. Therefore, Bcl-2 selectively inhibits proapoptotic Ca2+ elevation induced by strong TCR activation without hindering prosurvival Ca2+ signals induced by weak TCR activation.

T cell receptor activation status as biological context for interpreting PD1/PDL1 biomarker measurements.

2018 ◽  
Vol 36 (5_suppl) ◽  
pp. 54-54
Author(s):  
Ralph E. Parchment ◽  
Tony Navas ◽  
Kristin Fino ◽  
Andy Fung ◽  
Facundo Cutuli ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Tumor Immunity ◽  
Cd8 T Cells ◽  
Immune Checkpoint ◽  
Immunofluorescence Microscopy ◽  
Cell Receptor ◽  
Receptor Activation ◽  
Tcr Activation

54 Background: Direct cytolysis of tumor cells by CD8+ T cells results from the net effect of at least two biochemical pathways: (1) stimulatory signaling from the activated T cell receptor (TCR) complex in response to its recognition of a tumor neoantigen presented in the context of autologous MHC class I, and (2) suppressive signaling from immune checkpoints, such as the response of PD1 to binding its ligand, PDL1. Because the PD1:PDL1 immune checkpoint is significant for therapy only when there is tumor cell-specific TCR activation and signaling, it is not surprising that simple measurements of either PD1 or PDL1 in tumor biopsies are, at best, imperfect predictive biomarkers. Instead, a more precise test that quantifies PD1 signaling due to PDL1 binding only in the subset of CD8+ T cells exhibiting activated TCR signaling should provide a more accurate assessment of the extent of immune checkpoint suppression of tumor immunity and therefore be a more predictive biomarker of response to PD1/PDL1-targeted immunotherapy. Methods: We have developed a multiplexed immunofluorescence microscopy test capable of simultaneous quantitation of TCR activation (phospho-CD3zeta), immune checkpoint signaling via PD1 (phospho-SHP1 and -SHP2), and the net stimulation or inhibition resulting from the integration of these two pathways (phospho-ZAP70). Results: Specific antibodies to these biomarkers have been qualified, including peptide inhibition studies to establish antibody specificity, and their performance established by fit-for-purpose studies of in vitro models of CD8+ T cell activation. This multiplex biomarker panel is suitable for clinical use with formalin-fixed, paraffin embedded core needle biopsies of tumor and quantitative immunofluorescence microscopy (qIFA). Conclusions: The additional biomarkers of tumor immunity are expected to add an important context for interpreting PD1/PDL1 measurements. Funded by NCI Contract No. HHSN261200800001E.

scholarly journals Regulation of T cell receptor signaling by activation-induced zinc influx

2011 ◽  
Vol 208 (4) ◽  
pp. 775-785 ◽  
Author(s):  
Mingcan Yu ◽  
Won-Woo Lee ◽  
Deepak Tomar ◽  
Sergey Pryshchep ◽  
Marta Czesnikiewicz-Guzik ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Cell Activation ◽  
Calcium Influx ◽  
Cell Receptor ◽  
Structural Element ◽  
Zinc Bioavailability ◽  
Zinc Concentrations ◽  
Tcr Activation

Zinc is a trace element that is essential for innate and adaptive immune responses. In addition to being a structural element of many proteins, zinc also functions as a neurotransmitter and an intracellular messenger. Temporal or spatial changes in bioavailable zinc may influence the activity of several enzymes, including kinases and phosphatases. We provide evidence that zinc functions as an ionic signaling molecule after T cell activation. Cytoplasmic zinc concentrations increased within 1 min after T cell receptor (TCR) triggering, in particular in the subsynaptic compartment. The increase depended on the extracellular zinc concentrations and was inhibited by silencing zinc transporter Zip6. Increased zinc influx reduced the recruitment of SHP-1 to the TCR activation complex, augmented ZAP70 phosphorylation and sustained calcium influx. By calibrating TCR activation thresholds, increased extracellular zinc bioavailability facilitated the induction of T cell proliferative responses to suboptimal stimuli.

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