Minimal requirement of tyrosine residues of linker for activation of T cells in TCR signaling and thymocyte development
Minimal requirement of tyrosine residues of linker for activation of T cells in TCR signaling and thymocyte development
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DOI：
10.4049/jimmunol.170.1.325
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发表时间：
2003-01-01
影响因子：
4.4
通讯作者：
Zhang, WG
中科院分区：
文献类型：
--
作者：
Zhu, NH;Janssen, E;Zhang, WG
T细胞活化连接子（linkker for activation of T cells， LAT）是一种膜相关的连接蛋白，在TCR交联时被多个酪氨酸磷酸化。先前的研究表明，LAT对tcr介导的信号传导和胸腺细胞发育至关重要。在本研究中，我们在缺乏LAT的J.CaM2.5细胞中表达了一系列LAT Tyr到Phe突变体，并检测了它们的酪氨酸磷酸化；与Grb2、Gads和磷脂酶C (PLC)-gamma1的关联；和T细胞活化的功能我们的研究结果表明，这五种膜端酪氨酸在T细胞活化时被磷酸化。Grb2、Gads和PLC-gamma1通过不同的酪氨酸残基优先与LAT相关；然而，它们不能与只含有一个酪氨酸的LAT突变体相互作用。我们还确定了LAT酪氨酸残基在T细胞活化和胸腺细胞发育中的最低需求。我们的研究结果表明，LAT至少需要三个酪氨酸才能在T细胞激活和胸腺细胞发育中发挥作用。能够结合Grb2和PLC-gamma1的LAT突变体可以重建LAT缺陷细胞中的T细胞激活和LAT缺陷小鼠的胸腺细胞发育。
Linker for activation of T cells (LAT) is a membrane-associated adaptor protein that is phosphorylated on multiple tyrosines upon TCR cross-linking. Previous studies show that LAT is essential for TCR-mediated signaling and thymocyte development. In this study, we expressed a series of LAT Tyr to Phe mutants in LAT-deficient J.CaM2.5 cells and examined their tyrosine phosphorylation; association with Grb2, Gads, and phospholipase C (PLC)-gamma1; and function in T cell activation. Our results showed that the five membrane-distal tyrosines were phosphorylated upon T cell activation. Grb2, Gads, and PLC-gamma1 associated with LAT preferentially via different sets of tyrosine residues; however, they failed to interact with LAT mutants containing only one tyrosine. We also determined the minimal requirement of LAT tyrosine residues in T cell activation and thymocyte development. Our results showed that a minimum of three tyrosines is required for LAT to function in T cell activation and thymocyte development. LAT mutants that were capable of binding Grb2 and PLC-gamma1 could reconstitute T cell activation in LAT-deficient cells and thymocyte development in LAT-deficient mice.