scholarly journals Shp1 regulates T cell homeostasis by limiting IL-4 signals

2013 ◽  
Vol 210 (7) ◽  
pp. 1419-1431 ◽  
Author(s):  
Dylan J. Johnson ◽  
Lily I. Pao ◽  
Salim Dhanji ◽  
Kiichi Murakami ◽  
Pamela S. Ohashi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Biology ◽  
Tyrosine Phosphatase ◽  
Elevated Serum ◽  
Premature Death ◽  
Negative Regulator ◽  
T Cell Homeostasis ◽  
Tcr Signaling ◽  
Regulatory Molecule

The protein-tyrosine phosphatase Shp1 is expressed ubiquitously in hematopoietic cells and is generally viewed as a negative regulatory molecule. Mutations in Ptpn6, which encodes Shp1, result in widespread inflammation and premature death, known as the motheaten (me) phenotype. Previous studies identified Shp1 as a negative regulator of TCR signaling, but the severe systemic inflammation in me mice may have confounded our understanding of Shp1 function in T cell biology. To define the T cell–intrinsic role of Shp1, we characterized mice with a T cell–specific Shp1 deletion (Shp1fl/fl CD4-cre). Surprisingly, thymocyte selection and peripheral TCR sensitivity were unaltered in the absence of Shp1. Instead, Shp1fl/fl CD4-cre mice had increased frequencies of memory phenotype T cells that expressed elevated levels of CD44. Activation of Shp1-deficient CD4+ T cells also resulted in skewing to the Th2 lineage and increased IL-4 production. After IL-4 stimulation of Shp1-deficient T cells, Stat 6 activation was sustained, leading to enhanced Th2 skewing. Accordingly, we observed elevated serum IgE in the steady state. Blocking or genetic deletion of IL-4 in the absence of Shp1 resulted in a marked reduction of the CD44hi population. Therefore, Shp1 is an essential negative regulator of IL-4 signaling in T lymphocytes.

scholarly journals Bystander hyperactivation of preimmune CD8+ T cells in chronic HCV patients

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Cécile Alanio ◽  
Francesco Nicoli ◽  
Philippe Sultanik ◽  
Tobias Flecken ◽  
Brieuc Perot ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chronic Infection ◽  
Surface Expression ◽  
Cross Sectional Study ◽  
Negative Regulator ◽  
Tcr Signaling ◽  
Cell Repertoire ◽  
Cross Sectional ◽  
Chronic Hcv

Chronic infection perturbs immune homeostasis. While prior studies have reported dysregulation of effector and memory cells, little is known about the effects on naïve T cell populations. We performed a cross-sectional study of chronic hepatitis C (cHCV) patients using tetramer-associated magnetic enrichment to study antigen-specific inexperienced CD8+ T cells (i.e., tumor or unrelated virus-specific populations in tumor-free and sero-negative individuals). cHCV showed normal precursor frequencies, but increased proportions of memory-phenotype inexperienced cells, as compared to healthy donors or cured HCV patients. These observations could be explained by low surface expression of CD5, a negative regulator of TCR signaling. Accordingly, we demonstrated TCR hyperactivation and generation of potent CD8+ T cell responses from the altered T cell repertoire of cHCV patients. In sum, we provide the first evidence that naïve CD8+ T cells are dysregulated during cHCV infection, and establish a new mechanism of immune perturbation secondary to chronic infection.

scholarly journals Themis-associated phosphatase activity controls signaling in T cell development

2018 ◽  
Vol 115 (48) ◽  
pp. E11331-E11340 ◽  
Author(s):  
Monika Mehta ◽  
Joanna Brzostek ◽  
Elijah W. Chen ◽  
Desmond W. H. Tung ◽  
Shuting Chen ◽  
...  
Keyword(s):  
T Cell ◽  
Phosphatase Activity ◽  
Ex Vivo ◽  
Tyrosine Phosphatase ◽  
Cell Receptor ◽  
Conditional Knockout ◽  
Negative Regulator ◽  
Tcr Signaling ◽  
Thymic Development ◽  
Double Deletion

Thymocyte-expressed molecule involved in selection (Themis) has been shown to be important for T cell selection by setting the threshold for positive versus negative selection. Themis interacts with the protein tyrosine phosphatase (PTP) Src-homology domain containing phosphatase-1 (Shp1), a negative regulator of the T cell receptor (TCR) signaling cascade. However, how Themis regulates Shp1 is still not clear. Here, using a very sensitive phosphatase assay on ex vivo thymocytes, we have found that Themis enhances Shp1 phosphatase activity by increasing its phosphorylation. This positive regulation of Shp1 activity by Themis is found in thymocytes, but not in peripheral T cells. Shp1 activity is modulated by different affinity peptide MHC ligand binding in thymocytes. Themis is also associated with phosphatase activity, due to its constitutive interaction with Shp1. In the absence of Shp1 in thymocytes, Themis interacts with Shp2, which leads to almost normal thymic development in Shp1 conditional knockout (cKO) mice. Double deletion of both Themis and Shp1 leads to a thymic phenotype similar to that of Themis KO. These findings demonstrate unequivocally that Themis positively regulates Shp1 phosphatase activity in TCR-mediated signaling in developing thymocytes.

scholarly journals Small molecule inhibition of Csk alters affinity recognition by T cells

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Boryana N Manz ◽  
Ying Xim Tan ◽  
Adam H Courtney ◽  
Florentine Rutaganira ◽  
Ed Palmer ◽  
...  
Keyword(s):  
T Cells ◽  
Catalytic Activity ◽  
T Cell ◽  
Small Molecule ◽  
Src Family Kinases ◽  
Negative Regulator ◽  
Proliferation Inhibition ◽  
Tcr Signaling ◽  
Cell Responses ◽  
Small Molecule Inhibition

The C-terminal Src kinase (Csk), the primary negative regulator of Src-family kinases (SFK), plays a crucial role in controlling basal and inducible receptor signaling. To investigate how Csk activity regulates T cell antigen receptor (TCR) signaling, we utilized a mouse expressing mutated Csk (CskAS) whose catalytic activity is specifically and rapidly inhibited by a small molecule. Inhibition of CskAS during TCR stimulation led to stronger and more prolonged TCR signaling and to increased proliferation. Inhibition of CskAS enhanced activation by weak but strictly cognate agonists. Titration of Csk inhibition revealed that a very small increase in SFK activity was sufficient to potentiate T cell responses to weak agonists. Csk plays an important role, not only in basal signaling, but also in setting the TCR signaling threshold and affinity recognition.

scholarly journals CD45 functions as a signaling gatekeeper in T cells

2019 ◽  
Vol 12 (604) ◽  
pp. eaaw8151 ◽  
Author(s):  
Adam H. Courtney ◽  
Alexey A. Shvets ◽  
Wen Lu ◽  
Gloria Griffante ◽  
Marianne Mollenauer ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Tcr Signaling ◽  
Downstream Signaling ◽  
High Affinity ◽  
Signaling Events ◽  
Genetic Perturbations ◽  
Computational Analyses

T cells require the protein tyrosine phosphatase CD45 to detect and respond to antigen because it activates the Src family kinase Lck, which phosphorylates the T cell antigen receptor (TCR) complex. CD45 activates Lck by opposing the negative regulatory kinase Csk. Paradoxically, CD45 has also been implicated in suppressing TCR signaling by dephosphorylating the same signaling motifs within the TCR complex upon which Lck acts. We sought to reconcile these observations using chemical and genetic perturbations of the Csk/CD45 regulatory axis incorporated with computational analyses. Specifically, we titrated the activities of Csk and CD45 and assessed their influence on Lck activation, TCR-associated ζ-chain phosphorylation, and more downstream signaling events. Acute inhibition of Csk revealed that CD45 suppressed ζ-chain phosphorylation and was necessary for a regulatable pool of active Lck, thereby interconnecting the activating and suppressive roles of CD45 that tune antigen discrimination. CD45 suppressed signaling events that were antigen independent or induced by low-affinity antigen but not those initiated by high-affinity antigen. Together, our findings reveal that CD45 acts as a signaling “gatekeeper,” enabling graded signaling outputs while filtering weak or spurious signaling events.

scholarly journals Trib1 regulates T cell differentiation during chronic infection by restraining the effector program

2020 ◽  
Vol 217 (5) ◽  
Author(s):  
Kelly S. Rome ◽  
Sarah J. Stein ◽  
Makoto Kurachi ◽  
Jelena Petrovic ◽  
Gregory W. Schwartz ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
Cell Function ◽  
T Cell Differentiation ◽  
Negative Regulator ◽  
Chronic Infections ◽  
Tcr Signaling ◽  
Viral Control ◽  
Cell Immunity

In chronic infections, the immune response fails to control virus, leading to persistent antigen stimulation and the progressive development of T cell exhaustion. T cell effector differentiation is poorly understood in the context of exhaustion, but targeting effector programs may provide new strategies for reinvigorating T cell function. We identified Tribbles pseudokinase 1 (Trib1) as a central regulator of antiviral T cell immunity, where loss of Trib1 led to a sustained enrichment of effector-like KLRG1+ T cells, enhanced function, and improved viral control. Single-cell profiling revealed that Trib1 restrains a population of KLRG1+ effector CD8 T cells that is transcriptionally distinct from exhausted cells. Mechanistically, we identified an interaction between Trib1 and the T cell receptor (TCR) signaling activator, MALT1, which disrupted MALT1 signaling complexes. These data identify Trib1 as a negative regulator of TCR signaling and downstream function, and reveal a link between Trib1 and effector versus exhausted T cell differentiation that can be targeted to improve antiviral immunity.

A Point Mutation in the Juxtamembrane Wedge of CD45 Impacts Myeloid Development and Generates a Novel Model for Hemophagocytic Disorders in the Context of a MHC I-Restricted Transgene.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 317-317 ◽  
Author(s):  
Michelle L. Hermiston ◽  
Fleur R. de Graaf ◽  
Art Weiss
Keyword(s):  
T Cells ◽  
T Cell ◽  
Point Mutation ◽  
Cd8 T Cells ◽  
Adoptive Transfer ◽  
Macrophage Activation ◽  
Tyrosine Phosphatase ◽  
Myeloid Cell ◽  
Premature Death ◽  
Regulatory Function

Abstract The receptor like-protein tyrosine phosphatase CD45 is highly expressed on all nucleated hematopoietic cells and functions by modulating the activity of Src family kinases. We previously generated mice containing a point mutation in the juxtamembrane wedge of CD45 that leads to constitutive phosphatase activity. Demonstrating the critical negative regulatory function of the wedge, the CD45E613R mutation led to a lymphoproliferative disorder, lupus-like autoimmune syndrome, and premature death at 9–12 months of age. To address the intrinsic effects of the wedge mutation on the CD8 T cell lineage, we introduced a CD8 restricted T-cell receptor (TCR) transgene, OT1, specific for the antigen ovalbumin, into CD45E613R mice. Surprisingly, 100% of the CD45E613R/OT1+ mice succumb by 6 weeks of age to a rapidly progressive disease characterized by severe cachexia, hemophagocytosis, and markedly elevated interferon gamma levels. This phenotype shares similarity to the human hemophagocytic syndromes hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS). The aims of this study are to identify the mechanistic basis and the cell type(s) responsible for this phenotype. Using a genetic approach, we demonstrate that the phenotype is maintained in CD45E613R/OT1+mice on a Rag1−/− background, thus implicating myeloid and/or CD8 T cells in disease pathogenesis. Analysis of myeloid cell development, phagocytic function, and signaling indicate that the wedge mutation operates in this lineage. Despite the intrinsic hyperresponsiveness of CD45E613R macrophages, adoptive transfer experiments demonstrate they are not essential for disease. However, adoptive transfer of purified CD45E613R/OT1+ CD8 T cells into either CD45 mutant or CD45 wildtype (wt) is sufficient to initiate disease. Interestingly, CD45E613R CD8 OT+ T cells are not dominant over CD45wt CD8+ cells. In addition we show that transfer of CD45wt CD8+ T cells into ill mice can delay disease progression. We hypothesize that, in the setting of the wedge mutation, the restricted repertoire of the CD8 T cells in CD45E613R/OT1+ mice might not be able to limit macrophage activation. We believe these mice may represent a useful model for understanding the molecular pathogenesis of hemophagocytic disorders, devastating and often fatal diseases in humans.

scholarly journals Yap suppresses T cell function and infiltration in the tumor microenvironment

2019 ◽  
Author(s):  
Eleni Stampouloglou ◽  
Anthony Federico ◽  
Emily Slaby ◽  
Stefano Monti ◽  
Gregory L. Szeto ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Microenvironment ◽  
T Cell Activation ◽  
Cell Biology ◽  
Cell Activation ◽  
Cell Function ◽  
T Cell Responses ◽  
Negative Regulator ◽  
Cell Responses

ABSTRACTA major challenge for cancer immunotherapy is sustaining T cell activation and recruitment in immunosuppressive solid tumors. Here we report that Yap levels are sharply induced upon activation of CD4+ and CD8+ T cells and that Yap functions as an immunosuppressive factor and inhibitor of effector differentiation. Loss of Yap in T cells results in enhanced T cell activation, differentiation and function, which translates in vivo to an improved ability for T cells to infiltrate and repress tumors. Gene expression analyses of tumor-infiltrating T cells following Yap deletion implicates Yap as a mediator of global T cell responses in the tumor microenvironment and as a key negative regulator of T cell tumor infiltration and patient survival in diverse human cancers. Collectively, our results indicate that Yap plays critical roles in T cell biology, and suggest that inhibiting Yap activity improves T cell responses in cancer.

scholarly journals Reporters of TCR signaling identify arthritogenic T cells in murine and human autoimmune arthritis

2018 ◽  
Author(s):  
Judith F. Ashouri ◽  
Lih-Yun Hsu ◽  
Steven Yu ◽  
Dmitry Rychkov ◽  
Yiling Chen ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Negative Regulator ◽  
Cytokine Signaling ◽  
Autoimmune Arthritis ◽  
Receptor Signaling ◽  
Tcr Signaling ◽  
Autoreactive T Cells

AbstractHow pathogenic CD4 T cells in Rheumatoid Arthritis (RA) develop remains poorly understood. We used Nur77—a marker of T cell antigen receptor (TCR) signaling—to identify antigen-activated CD4 T cells in the SKG mouse model of autoimmune arthritis and in patients with RA. Using a fluorescent reporter of Nur77 expression in SKG mice, we found that higher levels of Nur77-eGFP in SKG CD4 T cells marked their autoreactivity, arthritogenic potential, and ability to more readily differentiate into IL-17 producing cells. The T cells with increased autoreactivity, nonetheless had diminished ex vivo inducible TCR signaling, perhaps reflective of adaptive inhibitory mechanisms induced by chronic auto-antigen exposure in vivo. The enhanced autoreactivity was associated with upregulation of IL-6 cytokine signaling machinery, which might in part be attributable to a reduced amount of expression of suppressor of cytokine signaling 3 (SOCS3)—a key negative regulator of IL-6 signaling. As a result, the more autoreactive GFPhi CD4 T cells from SKGNur mice were hyper-responsive to IL-6 receptor signaling. Consistent with findings from SKGNur mice, SOCS3 expression was similarly downregulated in RA synovium. This suggests that, despite impaired TCR signaling, autoreactive T cells exposed to chronic antigen stimulation exhibit heightened sensitivity to IL-6 which contributes to the arthritogenicity in SKG mice, and perhaps in patients with RA.Significance StatementHow arthritis-causing T cells trigger rheumatoid arthritis (RA) is not understood since it is difficult to differentiate T cells activated by inflammation in arthritic joints from those activated through their TCR by self-antigens. We developed a model to identify and study antigen-specific T cell responses in arthritis. Nur77—a specific marker of TCR signaling—was used to identify antigen-activated CD4 T cells in the SKG arthritis model and patients with RA. Nur77 could distinguish highly arthritogenic and autoreactive T cells in SKG mice. The enhanced autoreactivity was associated with increased IL-6-receptor-signaling, likely contributing to their arthritogenicity. These data highlight a functional correlate between Nur77 expression, arthritogenic T cell populations, and heightened IL-6 sensitivity in SKG mice with translatable implications for human RA.

scholarly journals Dynamic regulation of CD45 by tetraspanin CD53

2019 ◽  
Author(s):  
V. E. Dunlock ◽  
A. B. Arp ◽  
E. Jansen ◽  
S. Charrin ◽  
S. J. van Deventer ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Surface ◽  
Tyrosine Phosphatase ◽  
Adaptive Immune Response ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Activated T Cells ◽  
Dynamic Regulation ◽  
And Function

AbstractT cells are central to the adaptive immune response, playing a role in both the direct and indirect killing of pathogens and transformed cells. The activation of T cells is the result of a complex signaling cascade, initiated at the T cell receptor (TCR), and ending with the induction of proliferation. CD45, a member of the protein tyrosine phosphatase family, is one of the most abundant membrane proteins on T cells and functions by regulating activation directly downstream of the TCR. As a result of alternative splicing, CD45 can be expressed in multiple isoforms, naive T cells express the CD45RA isoform, while activated T cells gain expression of CD45RO, which has been proposed to increase signaling. Though the importance of CD45 in TCR signaling, proliferation and cytokine production is well established, little is known about the regulation of CD45 activity. We discovered that the immune-specific tetraspanin CD53 directly affects the stability and function of CD45RO in T cells.We have identified CD53 as a T cell co-stimulatory molecule in primary human and murine cells. Furthermore, we have shown that the absence of CD53 leads to an altered CD45 isoform expression as a result of decreased CD45RO stability on the cell surface. This instability was accompanied by increased mobility as measured by FRAP.Together, this indicates that CD53 functions as a stabilizer of CD45RO, and therefore as a positive regulator of TCR signaling at the T cell surface. Our data provides novel insight into the role of tetraspanins in the regulation of immune signaling and may provide a new avenue for the regulation of T cell signaling.

scholarly journals Regulation of T-Cell Activation and Differentiation

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. SCI-11-SCI-11
Author(s):  
Golnaz Vahedi
Keyword(s):  
Rheumatoid Arthritis ◽  
T Cells ◽  
T Cell ◽  
Cell Biology ◽  
Janus Kinase ◽  
Negative Regulator ◽  
Cytokine Receptors ◽  
Pharmacological Intervention ◽  
Rheumatoid Arthritis Risk ◽  
Cell Identity

Abstract Enhancers regulate spatiotemporal gene expression and impart cell-specific transcriptional outputs that drive cell identity. Super-enhancers (SEs), also known as stretch-enhancers, are a subset of enhancers especially important for genes associated with cell identity and genetic risk of disease. CD4+ T cells are critical for host defence and autoimmunity. Here we analysed maps of mouse T-cell SEs as a non-biased means of identifying key regulatory nodes involved in cell specification. We found that cytokines and cytokine receptors were the dominant class of genes exhibiting SE architecture in T cells. Nonetheless, the locus encoding Bach2, a key negative regulator of effector differentiation, emerged as the most prominent T-cell SE, revealing a network in which SE-associated genes critical for T-cell biology are repressed by BACH2. Disease-associated single-nucleotide polymorphisms for immune-mediated disorders, including rheumatoid arthritis, were highly enriched for T-cell SEs versus typical enhancers or SEs in other cell lineages. Intriguingly, treatment of T cells with the Janus kinase (JAK) inhibitor tofacitinib disproportionately altered the expression of rheumatoid arthritis risk genes with SE structures. Together, these results indicate that genes with SE architecture in T cells encompass a variety of cytokines and cytokine receptors but are controlled by a 'guardian' transcription factor, itself endowed with an SE. Thus, enumeration of SEs allows the unbiased determination of key regulatory nodes in T cells, which are preferentially modulated by pharmacological intervention. Disclosures No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document