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 CD45 tyrosine phosphatase activity and membrane anchoring are required for T-cell antigen receptor signaling.

1994 ◽  
Vol 14 (12) ◽  
pp. 8078-8084 ◽  
Author(s):  
B B Niklinska ◽  
D Hou ◽  
C June ◽  
A M Weissman ◽  
J D Ashwell
Keyword(s):  
T Cells ◽  
T Cell ◽  
Phosphatase Activity ◽  
Catalytic Domain ◽  
Tyrosine Phosphatase ◽  
Cell Receptor ◽  
Single Amino Acid ◽  
Tcr Signaling ◽  
Antigen Receptor Signaling ◽  
Membrane Anchoring

T cells that lack the CD45 transmembrane tyrosine phosphatase have a variety of T-cell receptor (TCR) signaling defects that are corrected by reexpression of wild-type CD45 or its intracytoplasmic domains. In this study, a chimeric molecule containing the myristylation sequence of Src and the intracellular portion of CD45, previously shown to restore function in CD45- T cells, was mutagenized to determine if membrane-associated CD45 tyrosine phosphatase activity is required to restore TCR-mediated signaling in CD45- T cells. Abolition of enzymatic activity by substitution of a serine for a critical cysteine in the first catalytic domain resulted in failure of this molecule to restore TCR signaling. Another mutation, in which a single amino acid substitution destroyed the myristylation site, resulted in failure of the chimeric molecule to partition to the plasma membrane. Although expressed at high levels and enzymatically active, this form of intracellular CD45 also failed to restore normal signaling in CD45- T cells. These findings strongly suggest that CD45's function in TCR signaling requires its proximity to membrane-associated tyrosine phosphatase substrates.

scholarly journals c-Cbl expression levels regulate the functional responses of human central and effector memory CD4 T cells

Blood ◽  
2008 ◽  
Vol 112 (3) ◽  
pp. 652-660 ◽  
Author(s):  
Nicolò C. Brembilla ◽  
Johann Weber ◽  
Donata Rimoldi ◽  
Sylvain Pradervand ◽  
Frédéric Schütz ◽  
...  
Keyword(s):  
T Cell ◽  
Ex Vivo ◽  
Cell Receptor ◽  
Negative Regulator ◽  
T Cell Subsets ◽  
Effector Memory ◽  
Functional Responses ◽  
Tcr Signaling ◽  
Memory T Cell ◽  
Cell Functions

Abstract The biochemical mechanisms controlling the diverse functional outcomes of human central memory (CM) and effector memory (EM) T-cell responses triggered through the T-cell receptor (TCR) remain poorly understood. We implemented reverse phase protein arrays to profile TCR signaling components in human CD8 and CD4 memory T-cell subsets isolated ex vivo. As compared with CD4 CM cells, EM cells express statistically significant increased amounts of SLP-76 and reduced levels of c-Cbl, Syk, Fyn, and LAT. Moreover, in EM cells reduced expression of negative regulator c-Cbl correlates with expression of c-Cbl kinases (Syk and Fyn), PI3K, and LAT. Importantly, consistent with reduced expression of c-Cbl, EM cells display a lower functional threshold than CM cells. Increasing c-Cbl content of EM cells to the same level as that of CM cells using cytosolic transduction, we impaired their proliferation and cytokine production. This regulatory mechanism depends primarily on c-Cbl E3 ubiquitin ligase activity as evidenced by the weaker impact of enzymatically deficient c-Cbl C381A mutant on EM cell functions. Our study reports c-Cbl as a critical regulator of the functional responses of memory T cell subsets and identifies for the first time in humans a mechanism controlling the functional heterogeneity of memory CD4 cells.

CD45 tyrosine phosphatase activity and membrane anchoring are required for T-cell antigen receptor signaling

1994 ◽  
Vol 14 (12) ◽  
pp. 8078-8084
Author(s):  
B B Niklinska ◽  
D Hou ◽  
C June ◽  
A M Weissman ◽  
J D Ashwell
Keyword(s):  
T Cells ◽  
T Cell ◽  
Phosphatase Activity ◽  
Catalytic Domain ◽  
Tyrosine Phosphatase ◽  
Cell Receptor ◽  
Single Amino Acid ◽  
Tcr Signaling ◽  
Antigen Receptor Signaling ◽  
Membrane Anchoring

T cells that lack the CD45 transmembrane tyrosine phosphatase have a variety of T-cell receptor (TCR) signaling defects that are corrected by reexpression of wild-type CD45 or its intracytoplasmic domains. In this study, a chimeric molecule containing the myristylation sequence of Src and the intracellular portion of CD45, previously shown to restore function in CD45- T cells, was mutagenized to determine if membrane-associated CD45 tyrosine phosphatase activity is required to restore TCR-mediated signaling in CD45- T cells. Abolition of enzymatic activity by substitution of a serine for a critical cysteine in the first catalytic domain resulted in failure of this molecule to restore TCR signaling. Another mutation, in which a single amino acid substitution destroyed the myristylation site, resulted in failure of the chimeric molecule to partition to the plasma membrane. Although expressed at high levels and enzymatically active, this form of intracellular CD45 also failed to restore normal signaling in CD45- T cells. These findings strongly suggest that CD45's function in TCR signaling requires its proximity to membrane-associated tyrosine phosphatase substrates.

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 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 CD5 Expression Is Developmentally Regulated By T Cell Receptor (TCR) Signals and TCR Avidity

1998 ◽  
Vol 188 (12) ◽  
pp. 2301-2311 ◽  
Author(s):  
Hala S. Azzam ◽  
Alex Grinberg ◽  
Kin Lui ◽  
Howard Shen ◽  
Elizabeth W. Shores ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Surface Expression ◽  
Negative Regulator ◽  
Fine Tuning ◽  
Surface Glycoprotein ◽  
Tcr Signaling ◽  
Ligand Interaction ◽  
Cell Surface Glycoprotein

Recent data indicate that the cell surface glycoprotein CD5 functions as a negative regulator of T cell receptor (TCR)-mediated signaling. In this study, we examined the regulation of CD5 surface expression during normal thymocyte ontogeny and in mice with developmental and/or signal transduction defects. The results demonstrate that low level expression of CD5 on CD4−CD8− (double negative, DN) thymocytes is independent of TCR gene rearrangement; however, induction of CD5 surface expression on DN thymocytes requires engagement of the pre-TCR and is dependent upon the activity of p56lck. At the CD4+CD8+ (double positive, DP) stage, intermediate CD5 levels are maintained by low affinity TCR–major histocompatibility complex (MHC) interactions, and CD5 surface expression is proportional to both the surface level and signaling capacity of the TCR. High-level expression of CD5 on DP and CD4+ or CD8+ (single positive, SP) thymocytes is induced by engagement of the α/β-TCR by (positively or negatively) selecting ligands. Significantly, CD5 surface expression on mature SP thymocytes and T cells was found to directly parallel the avidity or signaling intensity of the positively selecting TCR–MHC-ligand interaction. Taken together, these observations suggest that the developmental regulation of CD5 in response to TCR signaling and TCR avidity represents a mechanism for fine tuning of the TCR signaling response.

PTPN22 Mutation Is Present in An Increased Proportion of ITP Patients.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3418-3418 ◽  
Author(s):  
Karl D’Silva ◽  
Mathew Zamora ◽  
John Gerlach ◽  
Kenneth A. Schwartz
Keyword(s):  
T Cell ◽  
Tyrosine Phosphatase ◽  
Autoimmune Disorder ◽  
Cell Receptor ◽  
Negative Regulator ◽  
Platelet Surface ◽  
Immune Mediated ◽  
Important Negative Regulator ◽  
Low Platelet Count ◽  
Restriction Length Polymorphism

Abstract Immune-mediated thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by low platelet count and antibody mediated platelet destruction. ITP may be due to a failure of T-cell tolerance. Protein tyrosine phosphatase non receptor type 22 (PTPN22) is an important negative regulator of signal transduction from the T cell receptor. A single nucleotide polymorphism 1858C>T in the PTPN22 gene has been associated with various autoimmune disorders. We hypothesize that the PTPN22 mutation 1858C>T would be present in a higher proportion of ITP patients and patients who carry the mutation would have an increased concentration of autologous antiplatelet IgG on their platelet surface. We genotyped 45 patients with ITP by a PCR based restriction length polymorphism(RFLP) to identify the mutation 1858C>T in the gene PTPN22. Ten patients (22%) were heterozygous for the PTPN22 mutation and 2 were homozygous for the mutation (4.4%). This compares with a frequency of 8.6% observed in a published population study of 960 controls who did not have autoimmune disease (p<0.0001) (Am. J. Hu. Genetics2004:75:330). All of the 12 ITP patients who carried the PTPN22 mutation had an increase in autologous platelet surface IgG (≥1250 molecules IgG/platelet)(Schwartz Am. J. Heme1990;33:167). We conclude that the PTPN22 1858C>T mutation is present in an increased proportion of ITP patients and that all 12 of the PTPN22 mutation positive patients were also positive for autologous antiplatelet IgG. Our results indicate that PTPN22 increases the probability of developing ITP.

scholarly journals DLGH1 Is a Negative Regulator of T-Lymphocyte Proliferation

2007 ◽  
Vol 27 (21) ◽  
pp. 7574-7581 ◽  
Author(s):  
Linda M. Stephenson ◽  
Bénédicte Sammut ◽  
Daniel B. Graham ◽  
Joaquim Chan-Wang ◽  
Karry L. Brim ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cell Receptor ◽  
Suppressor Gene ◽  
Negative Regulator ◽  
Tcr Signaling ◽  
Mammalian Embryo ◽  
T Lymphocyte Proliferation ◽  
Discs Large

ABSTRACT Discs large homolog 1 (DLGH1), a founding member of the membrane-associated guanylate kinase family of proteins containing PostSynaptic Density-95/Discs large/Zona Occludens-1 domains, is an ortholog of the Drosophila tumor suppressor gene Discs large. In the mammalian embryo, DLGH1 is essential for normal urogenital morphogenesis and the development of skeletal and epithelial structures. Recent reports also indicate that DLGH1 may be a critical mediator of signals triggered by the antigen receptor complex in T lymphocytes by functioning as a scaffold coordinating the activities of T-cell receptor (TCR) signaling proteins at the immune synapse. However, it remains unclear if DLGH1 functions to enhance or attenuate signals emanating from the TCR. Here, we used Dlgh1 gene-targeted mice to determine the requirement for DLGH1 in T-cell development and activation. Strikingly, while all major subsets of T cells appear to undergo normal thymic development in the absence of DLGH1, peripheral lymph node Dlgh1 −/− T cells show a hyper-proliferative response to TCR-induced stimulation. These data indicate that, consistent with the known function of Discs large proteins as tumor suppressors and attenuators of cell division, in T lymphocytes, DLGH1 functions as a negative regulator of TCR-induced proliferative responses.

scholarly journals Sts-2 Is a Phosphatase That Negatively Regulates Zeta-associated Protein (ZAP)-70 and T Cell Receptor Signaling Pathways

2011 ◽  
Vol 286 (18) ◽  
pp. 15943-15954 ◽  
Author(s):  
Boris San Luis ◽  
Ben Sondgeroth ◽  
Nicolas Nassar ◽  
Nick Carpino
Keyword(s):  
T Cell ◽  
Signaling Pathways ◽  
Phosphatase Activity ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Intracellular Signaling ◽  
Cell Activation ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Homologous Proteins

T cell activity is controlled in large part by the T cell receptor (TCR). The TCR detects the presence of foreign pathogens and activates the T cell-mediated immune reaction. Numerous intracellular signaling pathways downstream of the TCR are involved in the process of T cell activation. Negative regulation of these pathways helps prevent excessive and deleterious T cell responses. Two homologous proteins, Sts-1 and Sts-2, have been shown to function as critical negative regulators of TCR signaling. The phosphoglycerate mutase-like domain of Sts-1 (Sts-1PGM) has a potent phosphatase activity that contributes to the suppression of TCR signaling. The function of Sts-2PGM as a phosphatase has been less clear, principally because its intrinsic enzyme activity has been difficult to detect. Here, we demonstrate that Sts-2 regulates the level of tyrosine phosphorylation on targets within T cells, among them the critical T cell tyrosine kinase Zap-70. Utilizing new phosphorylated substrates, we demonstrate that Sts-2PGM has clear, albeit weak, phosphatase activity. We further pinpoint Sts-2 residues Glu-481, Ser-552, and Ser-582 as specificity determinants, in that an Sts-2PGM triple mutant in which these three amino acids are altered to their counterparts in Sts-1PGM has substantially increased activity. Our results suggest that the phosphatase activities of both suppressor of TCR signaling homologues cooperate in a similar but independent fashion to help set the threshold for TCR-induced T cell activation.

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