T Cell Receptor (TCR) Engagement in Apoptosis-defective, but Interleukin 2 (IL-2)–producing, T Cells Results in Impaired ZAP70/CD3-ζ Association

Sahuquillo, Almudena G.; Roumier, Anne; Teixeiro, Emma; Bragado, Rafael; Alarcón, Balbino

doi:10.1084/jem.187.8.1179

Cited by 36 publications

(34 citation statements)

References 61 publications

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“…Western blotting of tyrosine-phosphorylated proteins was performed essentially as described (18). To assess CD3 phosphorylation, T cells and peptide-pulsed APCs were cocultured and lysed in 1% Brij97 (SigmaAldrich) lysis buffer (10 mM Tris Cl (pH 7.8), 150 mM NaCl, 10 mM EDTA, 20 mM NaF, 1 mM Na 3 VO 4 , and Complete Protease Inhibitor Cocktail (Roche)) at 4°C for 1 h. Solubilized proteins were resolved by 6 -15% SDS-PAGE and transferred onto PVDF by semidry electroblotting, and tyrosine-phosphorylated proteins were detected using HRP-conjugated mAb PY20 (Transduction Laboratories) and ECL detection reagents (Amersham Biosciences).…”

Section: Western Blottingmentioning

confidence: 99%

Dendritic Cells Sensitize TCRs through Self-MHC-Mediated Src Family Kinase Activation

Meraner

Hořejšı́

Wölpl

et al. 2007

The Journal of Immunology

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It is unclear whether peptide-MHC class II (pMHC) complexes on distinct types of APCs differ in their capacity to trigger TCRs. In this study, we show that individual cognate pMHC complexes displayed by dendritic cells (DCs), as compared with nonprofessional APCs, are far better in productively triggering Ag-specific TCRs independently of conventional costimulation. As we further show, this is accomplished by the unique ability of DCs to robustly activate the Src family kinases (SFKs) Lck and Fyn in T cells even in the absence of cognate peptide. Instead, this form of SFK activation depends on interactions of DC-displayed MHC with TCRs of appropriate restriction, suggesting a central role of self-pMHC recognition. DC-mediated SFK activation leads to “TCR licensing,” a process that dramatically increases sensitivity and magnitude of the TCR response to cognate pMHC. Thus, TCR licensing, besides costimulation, is a main mechanism of DCs to present Ag effectively.

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Section: Western Blottingmentioning

confidence: 99%

Dendritic Cells Sensitize TCRs through Self-MHC-Mediated Src Family Kinase Activation

Meraner

Hořejšı́

Wölpl

et al. 2007

The Journal of Immunology

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“…We Of note, in none of the cell lines analysed (namely MEC-1, SKMM-1 and Nalm-6) ZAP-70 was found phosphorylated, after immunoprecipitation in contrast to Jurkat cells used as controls 21 (data not shown).…”

Section: Zap-70 Expression In Different B-cell Lines Representing Difmentioning

confidence: 99%

ZAP-70 is expressed by normal and malignant human B-cell subsets of different maturational stage

et al. 2006

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ZAP-70 tyrosine kinase is involved in signalling pathways following T-cell receptor stimulation and was originally described only in T cells and natural killer cells. ZAP-70 expression has been reported in normal mouse B lineage cells and in human malignant B lymphocytes, mainly in chronic lymphocytic leukemia (CLL) where it correlates with clinical outcome. We analyzed several B-cell lines and ex vivo malignant B cells, ranging from acute lymphoblastic leukemia to multiple myeloma and reflecting different stages of B-cell differentiation, and they showed ZAP-70 expression regardless their maturation stage. We then analyzed by Western blot and flow cytometry different human normal B-lymphocyte subpopulations: naïve, germinal center and memory B cells from tonsils, CD19 þ CD5 þ cells from cord blood and CD19 þ lymphocytes from peripheral blood. All expressed ZAP-70 protein, though at different levels depending on their differentiation, activation and tissue localization. In addition, ZAP-70 expression levels could be modulated following stimulation via the B-cell receptor. These findings implicate a potential role of ZAP-70 in the signalling pathway of B lymphocytes at different maturational stages, indicate that ZAP-70 expression is not a CLL-specific feature among B-cell malignancies and suggest that the absence of ZAP-70 rather than its presence should be considered abnormal for malignant B lymphocytes.

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“…Third, while TCR chains are functionally linked to both TCRs, physical association of TCR is much stronger with the ␣␤TCR than with the pre-TCR (8 -12). Notably, TCR has been shown to play a major role in TCR-mediated apoptosis in mature T cells (13)(14)(15)(16).…”

Section: Cd8mentioning

confidence: 99%

Opposite Ability of Pre-TCR and αβTCR to Induce Apoptosis

Steff

Trop

Maira

et al. 2001

The Journal of Immunology

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In early CD4−CD8− pro-thymocytes, signaling through the pre-TCR is crucial for survival and differentiation into CD4+CD8+ cells. At this more mature stage, interactions between αβTCR and self-Ag/MHC complexes in turn lead either to cell survival and differentiation (positive selection) or to cell death (negative selection). Intrinsic differences must therefore exist between pre-TCR signals in CD4−CD8− thymocytes and αβTCR signals in CD4+CD8+ cells, since only the latter can mediate a death signal. In this work, we directly compared the capability of pre-TCR and αβTCR to induce apoptosis in a CD4−CD8− thymoma cell line following receptor cross-linking with mAbs. Cross-linking of αβTCR triggered high levels of programmed cell death, mimicking the negative selection signal usually induced in CD4+CD8+ thymocytes. In contrast, pre-TCR was very inefficient at inducing apoptosis upon cross-linking, despite similar levels of surface receptor expression. Importantly, inefficient apoptosis induction by the pre-TCR did not result from its weak association with TCRζ chain, since TCRs containing α-pTα chimeric chains, binding weakly to TCRζ, were still able to induce apoptosis. Although similar tyrosine phosphorylation and calcium influx were induced after either pre-TCR or αβTCR cross-linking, the two pathways diverged at the level of Fas ligand induction. Among putative transcription factors involved in Fas ligand mRNA induction, Nur77 and NFAT transcriptional activities were readily induced after αβTCR, but not pre-TCR, stimulation. Together, these results support the view that the structure of the pre-TCR and αβTCR directly influences their apoptosis-inducing capabilities by activating distinct signaling pathways.

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T Cell Receptor (TCR) Engagement in Apoptosis-defective, but Interleukin 2 (IL-2)–producing, T Cells Results in Impaired ZAP70/CD3-ζ Association

Cited by 36 publications

References 61 publications

Dendritic Cells Sensitize TCRs through Self-MHC-Mediated Src Family Kinase Activation

Dendritic Cells Sensitize TCRs through Self-MHC-Mediated Src Family Kinase Activation

ZAP-70 is expressed by normal and malignant human B-cell subsets of different maturational stage

Opposite Ability of Pre-TCR and αβTCR to Induce Apoptosis

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