scholarly journals Reduced TCR signaling potential impairs negative selection but does not result in autoimmune disease

2012 ◽  
Vol 209 (10) ◽  
pp. 1781-1795 ◽  
Author(s):  
SuJin Hwang ◽  
Ki-Duk Song ◽  
Renaud Lesourne ◽  
Jan Lee ◽  
Julia Pinkhasov ◽  
...  
Keyword(s):  
Autoimmune Disease ◽  
Negative Selection ◽  
Cell Lineage ◽  
Foxp3 Expression ◽  
Cell Receptor ◽  
Chain Gene ◽  
Regulatory Sequences ◽  
Tcr Signaling ◽  
Gene Encoding ◽  
Downstream Signaling

Negative selection and regulatory T (T reg) cell development are two thymus-dependent processes necessary for the enforcement of self-tolerance, and both require high-affinity interactions between the T cell receptor (TCR) and self-ligands. However, it remains unclear if they are similarly impacted by alterations in TCR signaling potential. We generated a knock-in allele (6F) of the TCR ζ chain gene encoding a mutant protein lacking signaling capability whose expression is controlled by endogenous ζ regulatory sequences. Although negative selection was defective in 6F/6F mice, leading to the survival of autoreactive T cells, 6F/6F mice did not develop autoimmune disease. We found that 6F/6F mice generated increased numbers of thymus-derived T reg cells. We show that attenuation of TCR signaling potential selectively impacts downstream signaling responses and that this differential effect favors Foxp3 expression and T reg cell lineage commitment. These results identify a potential compensatory pathway for the enforcement of immune tolerance in response to defective negative selection caused by reduced TCR signaling capability.

scholarly journals Generation of CD19-chimeric antigen receptor modified CD8+ T cells derived from virus-specific central memory T cells

Blood ◽  
2012 ◽  
Vol 119 (1) ◽  
pp. 72-82 ◽  
Author(s):  
Seitaro Terakura ◽  
Tori N. Yamamoto ◽  
Rebecca A. Gardner ◽  
Cameron J. Turtle ◽  
Michael C. Jensen ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Lineage ◽  
Central Memory ◽  
Tcr Signaling ◽  
Gene Encoding ◽  
Adoptive Therapy ◽  
Downstream Signaling ◽  
Donor T Cells ◽  
Leukemia Relapse

Abstract The adoptive transfer of donor T cells that have been genetically modified to recognize leukemia could prevent or treat leukemia relapse after allogeneic HSCT (allo-HSCT). However, adoptive therapy after allo-HSCT should be performed with T cells that have a defined endogenous TCR specificity to avoid GVHD. Ideally, T cells selected for genetic modification would also have the capacity to persist in vivo to ensure leukemia eradication. Here, we provide a strategy for deriving virus-specific T cells from CD45RA−CD62L+CD8+ central memory T (TCM) cells purified from donor blood with clinical grade reagents, and redirect their specificity to the B-cell lineage marker CD19 through lentiviral transfer of a gene encoding a CD19-chimeric Ag receptor (CAR). Virus-specific TCM were selectively transduced by exposure to the CD19 CAR lentivirus after peptide stimulation, and bi-specific cells were subsequently enriched to high purity using MHC streptamers. Activation of bi-specific T cells through the CAR or the virus-specific TCR elicited phosphorylation of downstream signaling molecules with similar kinetics, and induced comparable cytokine secretion, proliferation, and lytic activity. These studies identify a strategy for tumor-specific therapy with CAR-modified T cells after allo-HSCT, and for comparative studies of CAR and TCR signaling.

scholarly journals SOX4 controls invariant NKT cell differentiation by tuning TCR signaling

2018 ◽  
Vol 215 (11) ◽  
pp. 2887-2900 ◽  
Author(s):  
Nidhi Malhotra ◽  
Yilin Qi ◽  
Nicholas A. Spidale ◽  
Michela Frascoli ◽  
Bing Miu ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Lineage ◽  
High Mobility ◽  
Allergic Diseases ◽  
Cell Receptor ◽  
Inkt Cells ◽  
Tcr Signaling ◽  
Nkt Cell ◽  
Essential Function ◽  
Lineage Diversification

Natural killer T (NKT) cells expressing the invariant T cell receptor (iTCR) serve an essential function in clearance of certain pathogens and have been implicated in autoimmune and allergic diseases. Complex effector programs of these iNKT cells are wired in the thymus, and upon thymic egress, they can respond within hours of antigenic challenges, classifying iNKT cells as innate-like. It has been assumed that the successful rearrangement of the invariant iTCRα chain is the central event in the divergence of immature thymocytes to the NKT cell lineage, but molecular properties that render the iTCR signaling distinct to permit the T cell lineage diversification remain obscure. Here we show that the High Mobility Group (HMG) transcription factor (TF) SOX4 controls the production of iNKT cells by inducing MicroRNA-181 (Mir181) to enhance TCR signaling and Ca2+ fluxes in precursors. These results suggest the existence of tailored, permissive gene circuits in iNKT precursors for innate-like T cell development.

scholarly journals Phosphorylation of a Tyrosine Residue on Zap70 by Lck and Its Subsequent Binding via an SH2 Domain May Be a Key Gatekeeper of T Cell Receptor SignalingIn Vivo

2016 ◽  
Vol 36 (18) ◽  
pp. 2396-2402 ◽  
Author(s):  
Peter A. Thill ◽  
Arthur Weiss ◽  
Arup K. Chakraborty
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Receptor Activation ◽  
Sh2 Domain ◽  
Tcr Signaling ◽  
New Model ◽  
Downstream Signaling ◽  
Conventional Models

The initiation of signaling in T lymphocytes in response to the binding of the T cell receptor (TCR) to cognate ligands is a key step in the emergence of adaptive immune responses. Conventional models posit that TCR signaling is initiated by the phosphorylation of receptor-associated immune receptor activation motifs (ITAMs). The cytoplasmic tyrosine kinase Zap70 binds to phosphorylated ITAMs, is subsequently activated, and then propagates downstream signaling. While evidence for such models is provided by experiments with cell lines,in vivo, Zap70 is bound to phosphorylated ITAMs in resting T cells. However, Zap70 is activated only upon TCR binding to cognate ligand. We report the results of computational studies of a new model for the initiation of TCR signaling that incorporates thesein vivoobservations. Importantly, the new model is shown to allow better and faster TCR discrimination between self-ligands and foreign ligands. The new model is consistent with many past experimental observations, and experiments that could further test the model are proposed.

scholarly journals A hypomorphic allele of ZAP-70 reveals a distinct thymic threshold for autoimmune disease versus autoimmune reactivity

2009 ◽  
Vol 206 (11) ◽  
pp. 2527-2541 ◽  
Author(s):  
Lih-Yun Hsu ◽  
Ying Xim Tan ◽  
Zheng Xiao ◽  
Marie Malissen ◽  
Arthur Weiss
Keyword(s):  
T Cell ◽  
Autoimmune Disease ◽  
T Regulatory Cells ◽  
Mutant Mouse ◽  
Cell Receptor ◽  
Regulatory Cells ◽  
Tcr Signaling ◽  
Hypomorphic Mutation ◽  
Relative Contribution ◽  
Tcr Repertoire

ZAP-70 is critical for T cell receptor (TCR) signaling. Tyrosine to phenylalanine mutations of Y315 and Y319 in ZAP-70 suggest these residues function to recruit downstream effector molecules, but mutagenesis and crystallization studies reveal that these residues also play an important role in autoinhibition ZAP-70. To address the importance of the scaffolding function, we generated a zap70 mutant mouse (YYAA mouse) with Y315 and Y319 both mutated to alanines. These YYAA mice reveal that the scaffolding function is important for normal development and function. Moreover, the YYAA mice have many similarities to a previously identified ZAP-70 mutant mouse, SKG, which harbors a distinct hypomorphic mutation. Both YYAA and SKG mice have impaired T cell development and hyporesponsiveness to TCR stimulation, markedly reduced numbers of thymic T regulatory cells and defective positive and negative selection. YYAA mice, like SKG mice, develop rheumatoid factor antibodies, but fail to develop autoimmune arthritis. Signaling differences that result from ZAP-70 mutations appear to skew the TCR repertoire in ways that differentially influence propensity to autoimmunity versus autoimmune disease susceptibility. By uncoupling the relative contribution from T regulatory cells and TCR repertoire during thymic selection, our data help to identify events that may be important, but alone are insufficient, for the development of autoimmune disease.

scholarly journals A Novel, LAT/Lck Double Deficient T Cell Subline J.CaM1.7 for Combined Analysis of Early TCR Signaling

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 343
Author(s):  
Inmaculada Vico-Barranco ◽  
Mikel M. Arbulo-Echevarria ◽  
Isabel Serrano-García ◽  
Alba Pérez-Linaza ◽  
José M. Miranda-Sayago ◽  
...  
Keyword(s):  
T Cell ◽  
Intracellular Signaling ◽  
Adaptor Protein ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Downstream Signaling ◽  
Intracellular Signals ◽  
Cell Subline ◽  
And Function ◽  
Pkc Activation

Intracellular signaling through the T cell receptor (TCR) is essential for T cell development and function. Proper TCR signaling requires the sequential activities of Lck and ZAP-70 kinases, which result in the phosphorylation of tyrosine residues located in the CD3 ITAMs and the LAT adaptor, respectively. LAT, linker for the activation of T cells, is a transmembrane adaptor protein that acts as a scaffold coupling the early signals coming from the TCR with downstream signaling pathways leading to cellular responses. The leukemic T cell line Jurkat and its derivative mutants J.CaM1.6 (Lck deficient) and J.CaM2 (LAT deficient) have been widely used to study the first signaling events upon TCR triggering. In this work, we describe the loss of LAT adaptor expression found in a subline of J.CaM1.6 cells and analyze cis-elements responsible for the LAT expression defect. This new cell subline, which we have called J.CaM1.7, can re-express LAT adaptor after Protein Kinase C (PKC) activation, which suggests that activation-induced LAT expression is not affected in this new cell subline. Contrary to J.CaM1.6 cells, re-expression of Lck in J.CaM1.7 cells was not sufficient to recover TCR-associated signals, and both LAT and Lck had to be introduced to recover activatory intracellular signals triggered after CD3 crosslinking. Overall, our work shows that the new LAT negative J.CaM1.7 cell subline could represent a new model to study the functions of the tyrosine kinase Lck and the LAT adaptor in TCR signaling, and their mutual interaction, which seems to constitute an essential early signaling event associated with the TCR/CD3 complex.

scholarly journals Tec Family Kinases Modulate Thresholds for Thymocyte Development and Selection

2000 ◽  
Vol 192 (7) ◽  
pp. 987-1000 ◽  
Author(s):  
Edward M. Schaeffer ◽  
Christine Broussard ◽  
Jayanta Debnath ◽  
Stacie Anderson ◽  
Daniel W. McVicar ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Fate ◽  
Negative Selection ◽  
Cell Function ◽  
Cell Receptor ◽  
Quantitative Model ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Tec Kinases

Tec family kinases are implicated in T cell receptor (TCR) signaling, and combined mutation of inducible T cell kinase (Itk) and resting lymphocyte kinase (Rlk)/Txk in mice dramatically impairs mature T cell function. Nonetheless, mutation of these kinases still permits T cell development. While itk−/− mice exhibit mild reductions in T cells with decreased CD4/CD8 cell ratios, rlk−/−itk−/− mice have improved total T cell numbers yet maintain decreased CD4/CD8 ratios. Using TCR transgenics and an in vitro thymocyte deletion model, we demonstrate that mutation of Tec kinases causes graded defects in thymocyte selection, leading to a switch from negative to positive selection in rlk−/−itk−/− animals. The reduction in both positive and negative selection and decreased CD4/CD8 ratios correlates with decreased biochemical parameters of TCR signaling, specifically defects in capacitive Ca2+ influx and activation of the mitogen-activated kinases extracellular signal–regulated kinase 1 and 2. Thus, Tec kinases influence cell fate determination by modulating TCR signaling, leading to altered thresholds for thymocyte selection. These results provide support for a quantitative model for thymic development and provide evidence that defects in negative selection can substantially alter thymic cellularity.

scholarly journals 7q32-q36 translocations in childhood T cell leukemia: cytogenetic evidence for involvement of the T cell receptor beta-chain gene

Blood ◽  
1987 ◽  
Vol 69 (1) ◽  
pp. 131-134 ◽  
Author(s):  
SC Raimondi ◽  
CH Pui ◽  
FG Behm ◽  
DL Williams
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Lymphoblastic Leukemia ◽  
Chromosomal Rearrangements ◽  
Cell Receptor ◽  
Chain Gene ◽  
Regulatory Sequences ◽  
Beta Chain ◽  
T Cell Receptor Beta ◽  
Receptor Beta

Abstract Blast cell chromosomal rearrangements involving the long arm of chromosome 7 were identified in eight of 197 cases of childhood acute lymphoblastic leukemia (ALL). Breakpoints were variable but tended to cluster in either the proximal or the terminal 7q region, depending on the immunophenotype of the cells. The 7q32–q36 region, the locus of the T cell receptor beta-chain gene, was the site of breakpoints in four of 31 cases of T cell ALL but was not involved in any of the 166 cases originating from B cell precursors (P less than .0004). In three of the four T cell cases it was possible to identify the chromosomal segment that had been translocated to the 7q32-q36 region: 1p32, 2p21, and 6p21. The 1p32 and 6p21 bands are particularly interesting, as they contain the sites of two known protooncogenes, c-L-myc and hpim, respectively. Our findings suggest that the locus of the beta-chain gene of the T cell receptor is a preferential site for certain chromosomal rearrangements in leukemic T lymphoblasts, analogous to the T cell receptor alpha-chain gene on human chromosome 14. Translocation of proto-oncogenes to a site near the beta-chain regulatory sequences provides a potential mechanism for oncogene activation.

scholarly journals T Cell Receptor Engagement Leads to Phosphorylation of Clathrin Heavy Chain during Receptor Internalization

2004 ◽  
Vol 199 (7) ◽  
pp. 981-991 ◽  
Author(s):  
Victoria L. Crotzer ◽  
Allan S. Mabardy ◽  
Arthur Weiss ◽  
Frances M. Brodsky
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Heavy Chain ◽  
Cd4 T Cells ◽  
Cell Receptor ◽  
Receptor Internalization ◽  
Tcr Signaling ◽  
Downstream Signaling ◽  
Clathrin Heavy Chain

T cell receptor (TCR) internalization by clathrin-coated vesicles after encounter with antigen has been implicated in the regulation of T cell responses. We demonstrate that TCR internalization after receptor engagement and TCR signaling involves inducible phosphorylation of clathrin heavy chain (CHC) in both CD4+ and CD8+ human T cells. Studies with mutant Jurkat T cells implicate the Src family kinase Lck as the responsible enzyme and its activity in this process is influenced by the functional integrity of the downstream signaling molecule ZAP-70. CHC phosphorylation positively correlates with ligand-induced TCR internalization in both CD4+ and CD8+ T cells, and CHC phosphorylation as a result of basal Lck activity is also implicated in constitutive TCR endocytosis by CD4+ T cells. Remarkably, irreversible CHC phosphorylation in the presence of pervanadate reduced both constitutive and ligand-induced TCR internalization in CD4+ T cells, and immunofluorescence studies revealed that this inhibition affected the early stages of TCR endocytosis from the plasma membrane. Thus, we propose that CHC phosphorylation and dephosphorylation are involved in TCR internalization and that this is a regulatory mechanism linking TCR signaling to endocytosis.

scholarly journals Rearrangements of immunoglobulin and T cell receptor beta and gamma genes are associated with terminal deoxynucleotidyl transferase expression in acute myeloid leukemia.

1987 ◽  
Vol 165 (3) ◽  
pp. 879-890 ◽  
Author(s):  
R Foa ◽  
G Casorati ◽  
M C Giubellino ◽  
G Basso ◽  
R Schirò ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Gene Rearrangement ◽  
Cell Lineage ◽  
Cell Receptor ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Chain Gene ◽  
T Cell Receptor Beta ◽  
Receptor Beta ◽  
Acute Myeloid

The cell origin of the rare terminal deoxynucleotidyl transferase (TdT)-positive acute myeloid leukemias (AML) was investigated at the molecular level, by examining the configuration of the Ig H (Igh) and L (Ig kappa, Ig lambda) chain gene regions, and of the T cell receptor (TCR) beta and T cell rearranging (TRG) gamma loci. In 8 of the 10 TdT+ AML analyzed (classified as myeloid according to morphological and cytochemical criteria, and to the reactivity with one or more antimyeloid mAbs), a rearrangement of the Igh chain gene was found. In TdT- AML, evidence of an Igh gene reorganization was instead observed only in 2 of the 42 patients studied. Furthermore, evidence of TCR-beta and/or TRG-gamma gene rearrangement was observed in four AML, all of which belonged to the Igh-rearranged TdT+ group. In three cases (one TdT+ and two TdT-), the Ig kappa L chain gene was also in a rearranged position. These findings demonstrate a highly significant correlation between TdT expression and DNA rearrangements at the Igh and TCR chain gene regions and support the view that this enzyme plays an important role in the V-(D)-J recombination machinery. Overall, the genomic configuration, i.e., JH gene rearrangement sometimes coupled to a kappa L chain and TCR gene reorganization, similar to that found in non-T-ALL, suggests that in most cases of TdT+ AML, the neoplastic clone, despite the expression of myeloid-related features, is characterized by cells molecularly committed along the B cell lineage.

scholarly journals microRNA-mediated regulation of mTOR complex components facilitates discrimination between activation and anergy in CD4 T cells

2014 ◽  
Vol 211 (11) ◽  
pp. 2281-2295 ◽  
Author(s):  
Antoine Marcais ◽  
Rory Blevins ◽  
Johannes Graumann ◽  
Amelie Feytout ◽  
Gopuraja Dharmalingam ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Foxp3 Expression ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Tcr Signals ◽  
Mtor Activity

T cell receptor (TCR) signals can elicit full activation with acquisition of effector functions or a state of anergy. Here, we ask whether microRNAs affect the interpretation of TCR signaling. We find that Dicer-deficient CD4 T cells fail to correctly discriminate between activating and anergy-inducing stimuli and produce IL-2 in the absence of co-stimulation. Excess IL-2 production by Dicer-deficient CD4 T cells was sufficient to override anergy induction in WT T cells and to restore inducible Foxp3 expression in Il2-deficient CD4 T cells. Phosphorylation of Akt on S473 and of S6 ribosomal protein was increased and sustained in Dicer-deficient CD4 T cells, indicating elevated mTOR activity. The mTOR components Mtor and Rictor were posttranscriptionally deregulated, and the microRNAs Let-7 and miR-16 targeted the Mtor and Rictor mRNAs. Remarkably, returning Mtor and Rictor to normal levels by deleting one allele of Mtor and one allele of Rictor was sufficient to reduce Akt S473 phosphorylation and to reduce co-stimulation–independent IL-2 production in Dicer-deficient CD4 T cells. These results show that microRNAs regulate the expression of mTOR components in T cells, and that this regulation is critical for the modulation of mTOR activity. Hence, microRNAs contribute to the discrimination between T cell activation and anergy.

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