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T cell receptor signal transduction involved in T cell anergy

T细胞受体信号转导参与T细胞无反应性

基本信息

批准号：
11694312
负责人：
KOYASU Shigeo
金额：
$ 4.42万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11694312/
关键词：
tolerance ZAP70 ITAM T cell receptor MAP kinase superfamily CD2 JNT MAPKスーパーファミリー T細胞受容体カルシウムイオンの動員

项目摘要

1) Immunoreceptor tyrosine-based activation motif (ITAM), consisting of two YxxL segments, transmits signals leading to IL-2 gene activation in T cells. We investigated the functional difference between these two YxxL segments in the ITAM-mediated signal transduction. N-terminal YxxL mutants failed to induce ZAP70 phosphorylation, elevation of intracellular Ca2^+ concentration ([Ca2^+]i) or extracellular signal-regulated kinase (ERK) activation even in the presence of CD28 co-stimulation, whereas a mutant of the leucine residue at the C-terminal YxxL segment retainedlhe ability to induce these events although this mutation abrogates the ability to induce IL-2 gene activation. In marked contrast to ERK activation, c-Jun NH2-terminal kinase (INK) activation was observed in all mutants when co-stimulated with CD28. The mutant of the leucine residue at the C-terminal YxxL segment had defect in the transcriptional activation at the NF-AT cis-element, which was restored to the wild type leve … More l by addition of calcium ionophore, suggesting that the intensity and/or duration of [Ca2+]i elevation defines the threshold of T cell activation in this mutant. Our data collectively indicate that the activation pathways of ERK, JNK and calcium mobilization are differentially regulated through YxxL segments of an ITAM.2) Stimulation with specific pairs of anti-CD2 antibodies can induce T cell activation and proliferation. Since involvement of CD2 in T cell anergy has been proposed, we examined the role of ZAP70 in CD2-mediated signal transduction. We investigated the significance of ZAP-70 in CD2 signaling using ZAP-70 deficient T cells derived from a CDS deficient patient and showed that ZAP-70 is necessary for cellular proliferation and cytokine production in T cells stimulated via CD2. Biochemical analyses showed that CD2 stimulation induced activation of mitogen-activated protein kinase (MAPK) super family in ZAP-70 deficient T cells, indicating that a ZAP-70 independent pathway(s) exists for MAPK super family activation in GDI-triggered human T cells. In contrast, intracellular Ca2+ mobilization and activation of nuclear factor of activated T cells (NFAT) upon CD2 triggering were absent in these T cells. Furthermore, we found that pharmacological Ca2^+ elevation combined with CD2 stimulation restored NFAT activation and subsequent cytokine production in ZAP-70 deficient T cells. These results indicate that in CD2 signaling, ZAP-70 plays an essential role in Ca2^+ mobilization and NFAT activation. Less

1)免疫受体基于酪氨酸的激活基序（ITAM）由两个YxxL片段组成，传递导致T细胞中IL-2基因激活的信号。我们研究了这两个YxxL片段在ITAM介导的信号转导中的功能差异。N端YxxL突变体不能诱导ZAP 70磷酸化、胞内Ca 2 ^+浓度升高（[Ca 2 ^+]i）或细胞外信号调节激酶（ERK）激活，即使在存在CD 28共刺激的情况下，而C端YxxL片段亮氨酸残基的突变体保留了诱导这些事件的能力，尽管该突变废除了诱导IL-2基因激活的能力。与ERK活化形成鲜明对比的是，当与CD 28共刺激时，在所有突变体中观察到c-Jun NH 2-末端激酶（INK）活化。YxxL基因C端亮氨酸残基突变体在NF-AT顺式元件的转录激活功能上存在缺陷，突变后恢复到野生型水平。 ...更多信息 1通过添加钙离子载体，表明[Ca 2 +]i升高的强度和/或持续时间定义了该突变体中T细胞活化的阈值。我们的数据共同表明ERK、JNK和钙动员的活化途径通过ITAM的YxxL片段进行差异调节。2）用特异性抗CD 2抗体对刺激可以诱导T细胞活化和增殖。由于CD 2参与T细胞无能已被提出，我们研究了ZAP 70在CD 2介导的信号转导中的作用。我们使用来自CDS缺陷患者的ZAP-70缺陷型T细胞研究了ZAP-70在CD 2信号传导中的意义，并表明ZAP-70对于通过CD 2刺激的T细胞中的细胞增殖和细胞因子产生是必需的。生物化学分析显示，CD 2刺激诱导ZAP-70缺陷型T细胞中丝裂原活化蛋白激酶（MAPK）超家族的活化，表明GDI触发的人T细胞中存在MAPK超家族活化的ZAP-70独立途径。相反，在这些T细胞中不存在细胞内Ca 2+动员和在CD 2触发时活化T细胞的核因子（NFAT）的活化。此外，我们发现药理学上的Ca 2 ^+升高结合CD 2刺激恢复了ZAP-70缺陷型T细胞中NFAT的激活和随后的细胞因子产生。这些结果表明，在CD 2信号转导中，ZAP-70在Ca 2 ^+动员和NFAT活化中起着重要作用。少