scholarly journals Impaired Plasma Membrane Targeting of Grb2–Murine Son of Sevenless (mSOS) Complex and Differential Activation of the Fyn–T Cell Receptor (TCR)-ζ–Cbl Pathway Mediate T Cell Hyporesponsiveness in Autoimmune Nonobese Diabetic Mice

1997 ◽  
Vol 186 (6) ◽  
pp. 887-897 ◽  
Author(s):  
Konstantin Salojin ◽  
Jian Zhang ◽  
Mark Cameron ◽  
Bruce Gill ◽  
Guillermo Arreaza ◽  
...  
Keyword(s):  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
Mapk Pathway ◽  
Autoimmune Diabetes ◽  
Ras Signaling ◽  
Differential Activation ◽  
Nonobese Diabetic ◽  
Ras Activation ◽  
Son Of Sevenless

Nonobese diabetic (NOD) mouse thymocytes are hyporesponsive to T cell antigen receptor (TCR)-mediated stimulation of proliferation, and this T cell hyporesponsiveness may be causal to the onset of autoimmune diabetes in NOD mice. We previously showed that TCR-induced NOD T cell hyporesponsiveness is associated with a block in Ras activation and defective signaling along the PKC/Ras/MAPK pathway. Here, we report that several sequential changes in TCR-proximal signaling events may mediate this block in Ras activation. We demonstrate that NOD T cell hyporesponsiveness is associated with the (a) enhanced TCR-β–associated Fyn kinase activity and the differential activation of the Fyn–TCR-ζ–Cbl pathway, which may account for the impaired recruitment of ZAP70 to membrane-bound TCR-ζ; (b) relative inability of the murine son of sevenless (mSOS) Ras GDP releasing factor activity to translocate from the cytoplasm to the plasma membrane; and (c) exclusion of mSOS and PLC-γ1 from the TCR-ζ–associated Grb2/pp36–38/ZAP70 signaling complex. Our data suggest that altered tyrosine phosphorylation and targeting of the Grb2/pp36–38/ZAP70 complex to the plasma membrane and cytoskeleton and the deficient association of mSOS with this Grb2-containing complex may block the downstream activation of Ras and Ras-mediated amplification of TCR/CD3-mediated signals in hyporesponsive NOD T cells. These findings implicate mSOS as an important mediator of downregulation of Ras signaling in hyporesponsive NOD T cells.

scholarly journals Ras Activation in Jurkat T cells following Low-Grade Stimulation of the T-Cell Receptor Is Specific to N-Ras and Occurs Only on the Golgi Apparatus

2004 ◽  
Vol 24 (8) ◽  
pp. 3485-3496 ◽  
Author(s):  
Ignacio Perez de Castro ◽  
Trever G. Bivona ◽  
Mark R. Philips ◽  
Angel Pellicer
Keyword(s):  
T Cells ◽  
T Cell ◽  
Golgi Apparatus ◽  
Cell Receptor ◽  
Ras Signaling ◽  
Low Grade ◽  
Jurkat T Cells ◽  
Ras Activation ◽  
Ras Isoforms ◽  
Stimulation Of

ABSTRACT Ras activation is critical for T-cell development and function, but the specific roles of the different Ras isoforms in T-lymphocyte function are poorly understood. We recently reported T-cell receptor (TCR) activation of ectopically expressed H-Ras on the the Golgi apparatus of T cells. Here we studied the isoform and subcellular compartment specificity of Ras signaling in Jurkat T cells. H-Ras was expressed at much lower levels than the other Ras isoforms in Jurkat and several other T-cell lines. Glutathione S-transferase-Ras-binding domain (RBD) pulldown assays revealed that, although high-grade TCR stimulation and phorbol ester activated both N-Ras and K-Ras, low-grade stimulation of the TCR resulted in specific activation of N-Ras. Surprisingly, whereas ectopically expressed H-Ras cocapped with the TCRs in lipid microdomains of the Jurkat plasma membrane, N-Ras did not. Live-cell imaging of Jurkat cells expressing green fluorescent protein-RBD, a fluorescent reporter of GTP-bound Ras, revealed that N-Ras activation occurs exclusively on the Golgi apparatus in a phospholipase Cγ- and RasGRP1-dependent fashion. The specificity of N-Ras signaling downstream of low-grade TCR stimulation was dependent on the monoacylation of the hypervariable membrane targeting sequence. Our data show that, in contrast to fibroblasts stimulated with growth factors in which all three Ras isoforms become activated and signaling occurs at both the plasma membrane and Golgi apparatus, Golgi-associated N-Ras is the critical Ras isoform and intracellular pool for low-grade TCR signaling in Jurkat T cells.

scholarly journals Spontaneous Autoimmune Diabetes in Monoclonal T Cell Nonobese Diabetic Mice

1997 ◽  
Vol 186 (10) ◽  
pp. 1663-1676 ◽  
Author(s):  
Joan Verdaguer ◽  
Dennis Schmidt ◽  
Abdelaziz Amrani ◽  
Brad Anderson ◽  
Nuzhat Averill ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Beta Cell ◽  
Beta Cells ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Pancreatic Beta Cells ◽  
Autoimmune Diabetes ◽  
Nod Mice ◽  
Nonobese Diabetic

It has been established that insulin-dependent diabetes mellitus (IDDM) in nonobese diabetic (NOD) mice results from a CD4+ and CD8+ T cell–dependent autoimmune process directed against the pancreatic beta cells. The precise roles that beta cell–reactive CD8+ and CD4+ T cells play in the disease process, however, remain ill defined. Here we have investigated whether naive beta cell–specific CD8+ and CD4+ T cells can spontaneously accumulate in pancreatic islets, differentiate into effector cells, and destroy beta cells in the absence of other T cell specificities. This was done by introducing Kd– or I-Ag7–restricted beta cell–specific T cell receptor (TCR) transgenes that are highly diabetogenic in NOD mice (8.3- and 4.1-TCR, respectively), into recombination-activating gene (RAG)-2–deficient NOD mice, which cannot rearrange endogenous TCR genes and thus bear monoclonal TCR repertoires. We show that while RAG-2−/− 4.1-NOD mice, which only bear beta cell–specific CD4+ T cells, develop diabetes as early and as frequently as RAG-2+ 4.1-NOD mice, RAG-2−/− 8.3-NOD mice, which only bear beta cell–specific CD8+ T cells, develop diabetes less frequently and significantly later than RAG-2+ 8.3-NOD mice. The monoclonal CD8+ T cells of RAG-2−/− 8.3-NOD mice mature properly, proliferate vigorously in response to antigenic stimulation in vitro, and can differentiate into beta cell–cytotoxic T cells in vivo, but do not efficiently accumulate in islets in the absence of a CD4+ T cell–derived signal, which can be provided by splenic CD4+ T cells from nontransgenic NOD mice. These results demonstrate that naive beta cell– specific CD8+ and CD4+ T cells can trigger diabetes in the absence of other T or B cell specificities, but suggest that efficient recruitment of naive diabetogenic beta cell–reactive CD8+ T cells to islets requires the assistance of beta cell–reactive CD4+ T cells.

scholarly journals B7-H4 Pathway in Islet Transplantation andβ-Cell Replacement Therapies

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaojie Wang ◽  
Jianqiang Hao ◽  
Daniel L. Metzger ◽  
Ziliang Ao ◽  
Mark Meloche ◽  
...  
Keyword(s):  
T Cell ◽  
Islet Transplantation ◽  
Autoimmune Diabetes ◽  
Islet Cell Transplantation ◽  
T Cell Homeostasis ◽  
Allograft Survival ◽  
Cell Replacement ◽  
Nonobese Diabetic ◽  
Alloreactive T Cell ◽  
Donor Specific Tolerance

Type 1 diabetes (T1D) is a chronic autoimmune disease and characterized by absolute insulin deficiency.β-cell replacement by islet cell transplantation has been established as a feasible treatment option for T1D. The two main obstacles after islet transplantation are alloreactive T-cell-mediated graft rejection and recurrence of autoimmune diabetes mellitus in recipients. T cells play a central role in determining the outcome of both autoimmune responses and allograft survival. B7-H4, a newly identified B7 homolog, plays a key role in maintaining T-cell homeostasis by reducing T-cell proliferation and cytokine production. The relationship between B7-H4 and allograft survival/autoimmunity has been investigated recently in both islet transplantation and the nonobese diabetic (NOD) mouse models. B7-H4 protects allograft survival and generates donor-specific tolerance. It also prevents the development of autoimmune diabetes. More importantly, B7-H4 plays an indispensable role in alloimmunity in the absence of the classic CD28/CTLA-4 : B7 pathway, suggesting a synergistic/additive effect with other agents such as CTLA-4 on inhibition of unwanted immune responses.

scholarly journals T cell-mediated inhibition of the transfer of autoimmune diabetes in NOD mice.

1989 ◽  
Vol 169 (5) ◽  
pp. 1669-1680 ◽  
Author(s):  
C Boitard ◽  
R Yasunami ◽  
M Dardenne ◽  
J F Bach
Keyword(s):  
T Cells ◽  
Autoimmune Diabetes ◽  
Nod Mice ◽  
Insulin Dependent Diabetes Mellitus ◽  
Lymphoid Cells ◽  
Dependent Diabetes Mellitus ◽  
Spleen Cells ◽  
Nonobese Diabetic ◽  
Insulin Dependent ◽  
Onset Of Diabetes

The nonobese diabetic (NOD) mouse has recently been introduced as a model for insulin-dependent diabetes mellitus. The role of regulatory T cells in the development of antipancreatic autoimmunity in this model remains unclear. To evaluate the presence of suppressive phenomena, we used disease transfer by spleen cells from diabetic NOD mice into preirradiated adult recipients as a model for accelerated disease. Suppressor phenomena were detected by testing the protection afforded by lymphoid cells from nondiabetic NOD mice against diabetes transfer in irradiated recipients. Transfer of diabetes was delayed by reconstituting recipients with spleen cells from nondiabetic NOD donors. The greatest protection against diabetes transfer was conferred by spleen cells from 8-wk-old nondiabetic female NOD mice. Depletion experiments showed that the protection was dependent on CD4+ cells. Protection was also detected within thymic cells from nondiabetic NOD mice and protection conferred by spleen cells was abrogated by thymectomy of nondiabetic female, but not male, NOD donors at 3 wk of age. These findings indicate that suppressive CD4+ T cells that are dependent on the presence of the thymus may delay the onset of diabetes in female diabetes-prone NOD mice.

scholarly journals Requirement for an Intact T-Cell Actin and Tubulin Cytoskeleton for Efficient Assembly and Spread of Human Immunodeficiency Virus Type 1

2007 ◽  
Vol 81 (11) ◽  
pp. 5547-5560 ◽  
Author(s):  
Clare Jolly ◽  
Ivonne Mitar ◽  
Quentin J. Sattentau
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
Immunodeficiency Virus ◽  
Fixed Cell ◽  
Cell Spread ◽  
Hiv 1 ◽  
Cell Cell

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection of CD4+ T cells leads to the production of new virions that assemble at the plasma membrane. Gag and Env accumulate in the context of lipid rafts at the inner and outer leaflets of the plasma membrane, respectively, forming polarized domains from which HIV-1 buds. HIV-1 budding can result in either release of cell-free virions or direct cell-cell spread via a virological synapse (VS). The recruitment of Gag and Env to these plasma membrane caps in T cells is poorly understood but may require elements of the T-cell secretory apparatus coordinated by the cytoskeleton. Using fixed-cell immunofluorescence labeling and confocal microscopy, we observed a high percentage of HIV-1-infected T cells with polarized Env and Gag in capped, lipid raft-like assembly domains. Treatment of infected T cells with inhibitors of actin or tubulin remodeling disrupted Gag and Env compartmentalization within the polarized raft-like domains. Depolymerization of the actin cytoskeleton reduced Gag release and viral infectivity, and actin and tubulin inhibitors reduced Env incorporation into virions. Live- and fixed-cell confocal imaging and assay of de novo DNA synthesis by real-time PCR allowed quantification of HIV-1 cell-cell transfer. Inhibition of actin and tubulin remodeling in infected cells interfered with cell-cell spread across a VS and reduced new viral DNA synthesis. Based on these data, we propose that HIV-1 requires both actin and tubulin components of the T-cell cytoskeleton to direct its assembly and budding and to elaborate a functional VS.

scholarly journals Synergistic Assembly of Linker for Activation of T Cells Signaling Protein Complexes in T Cell Plasma Membrane Domains

2003 ◽  
Vol 278 (22) ◽  
pp. 20389-20394 ◽  
Author(s):  
Lorian C. Hartgroves ◽  
Joseph Lin ◽  
Hanno Langen ◽  
Tobias Zech ◽  
Arthur Weiss ◽  
...  
Keyword(s):  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
Protein Complexes ◽  
Membrane Domains ◽  
Cell Plasma Membrane ◽  
Signaling Protein ◽  
Cell Plasma ◽  
Plasma Membrane Domains

scholarly journals Superresolution imaging reveals nanometer- and micrometer-scale spatial distributions of T-cell receptors in lymph nodes

2016 ◽  
Vol 113 (26) ◽  
pp. 7201-7206 ◽  
Author(s):  
Ying S. Hu ◽  
Hu Cang ◽  
Björn F. Lillemeier
Keyword(s):  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
Lymph Nodes ◽  
T Cell Activation ◽  
T Cell Receptors ◽  
Cell Activation ◽  
Cell Receptors ◽  
Micrometer Scale

T cells become activated when T-cell receptors (TCRs) recognize agonist peptides bound to major histocompatibility complex molecules on antigen-presenting cells. T-cell activation critically relies on the spatiotemporal arrangements of TCRs on the plasma membrane. However, the molecular organizations of TCRs on lymph node-resident T cells have not yet been determined, owing to the diffraction limit of light. Here we visualized nanometer- and micrometer-scale TCR distributions in lymph nodes by light sheet direct stochastic optical reconstruction microscopy (dSTORM) and structured illumination microscopy (SIM). This dSTORM and SIM approach provides the first evidence, to our knowledge, of multiscale reorganization of TCRs during in vivo immune responses. We observed nanometer-scale plasma membrane domains, known as protein islands, on naïve T cells. These protein islands were enriched within micrometer-sized surface areas that we call territories. In vivo T-cell activation caused the TCR territories to contract, leading to the coalescence of protein islands and formation of stable TCR microclusters.

scholarly journals Reduced Incidence and Delayed Onset of Diabetes in Perforin-deficient Nonobese Diabetic Mice

1997 ◽  
Vol 186 (7) ◽  
pp. 989-997 ◽  
Author(s):  
David Kägi ◽  
Bernhard Odermatt ◽  
Peter Seiler ◽  
Rolf M. Zinkernagel ◽  
Tak W. Mak ◽  
...  
Keyword(s):  
T Cells ◽  
Autoimmune Diabetes ◽  
Cytotoxic T Cells ◽  
Disease Onset ◽  
Spontaneous Diabetes ◽  
Cell Loss ◽  
Β Cell ◽  
Nonobese Diabetic ◽  
Nonobese Diabetic Mice ◽  
Deficient Mice

To investigate the role of T cell–mediated, perforin-dependent cytotoxicity in autoimmune diabetes, perforin-deficient mice were backcrossed with the nonobese diabetes mouse strain. It was found that the incidence of spontaneous diabetes over a 1 yr period was reduced from 77% in perforin +/+ control to 16% in perforin-deficient mice. Also, the disease onset was markedly delayed (median onset of 39.5 versus 19 wk) in the latter. Insulitis with infiltration of CD4+ and CD8+ T cells occurred similarly in both groups of animals. Lower incidence and delayed disease onset were also evident in perforin-deficient mice when diabetes was induced by cyclophosphamide injection. Thus, perforin-dependent cytotoxicity is a crucial effector mechanism for β cell elimination by cytotoxic T cells in autoimmune diabetes. However, in the absence of perforin chronic inflammation of the islets can lead to diabetogenic β cell loss by less efficient secondary effector mechanisms.

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