Enrichment of Lck in lipid rafts regulates colocalized Fyn activation and the initiation of proximal signals through TCRαβ
Enrichment of Lck in lipid rafts regulates colocalized Fyn activation and the initiation of proximal signals through TCRαβ
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DOI：
10.4049/jimmunol.172.7.4266
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发表时间：
2004-04-01
影响因子：
4.4
通讯作者：
Julius, M
中科院分区：
文献类型：
--
作者：
Filipp, D;Leung, BL;Julius, M
最近的研究结果提供了深入了解的时间和空间的关系，管理lck依赖fyn激活，并证明TCR/CD 4诱导的激活和易位的lck进入脂筏和随后的激活共定位fyn。预测如下，直接将lck靶向脂筏将绕过并置TCR和CD 4-lck的要求，并拯救由对TCR β链恒定区特异性的Ab介导的细胞活化。本研究使用了一个小鼠IL-2依赖性CD 4（+）T细胞克隆变异体家族，其中抗TCRCbeta信号以lck依赖性方式受损。重要的是，这些变体响应Ag和mAb介导的TCR-CD 4共聚集，这两者都能够使CD 4相关的lck与TCR/CD 3复合物协调相互作用。我们以前已经证明，在这个系统中的抗TCRCbeta反应与激酶活性，膜相关的lck和预先形成的低磷酸化TCRzeta：zeta相关蛋白的70 kDa复合物的存在相关，这是在初级静息CD 4（+）T细胞中重现的表型。我们在这项研究中表明，野生型lck的强制表达实现了相同的TCR/CD 3复合物的基础组成，但没有拯救抗TCRCbeta信号。相比之下，C20 S/C23 S突变的lck（双半胱氨酸lck）的强制表达（其不能结合CD 4）挽救了抗TCRCbeta近端信号传导和细胞生长。双半胱氨酸lck靶向脂筏，与>98%的细胞fyn共定位，并导致基础fyn激酶活性增加7倍。CD 4和TCR的共聚集达到相同的结果。这些结果强调了脂筏在空间协调lck和fyn之间的相互作用中的关键作用，该相互作用预测了近端TCR/CD 3信号传导。
Recent results provide insight into the temporal and spatial relationship governing lck-dependent fyn activation and demonstrate TCR/CD4-induced activation and translocation of lck into lipid rafts and the ensuing activation of colocalized fyn. The prediction follows that directly targeting lck to lipid rafts will bypass the requirement for juxtaposing TCR and CD4-lck, and rescue cellular activation mediated by Ab specific for the constant region of TCRbeta chain. The present study uses a family of murine IL-2-dependent CD4(+) T cell clonal variants in which anti-TCRCbeta signaling is impaired in an lck-dependent fashion. Importantly, these variants respond to Ag- and mAb-mediated TCR-CD4 coaggregation, both of which enable the coordinated interaction of CD4-associated lck with the TCR/CD3 complex. We have previously demonstrated that anti-TCRCbeta responsiveness in this system correlates with the presence of kinase-active, membrane-associated lck and preformed hypophosphorylated TCRzeta:zeta-associated protein of 70 kDa complexes, a phenotype recapitulated in primary resting CD4(+) T cells. We show in this study that forced expression of wild-type lck achieved the same basal composition of the TCR/CD3 complex and yet did not rescue anti-TCRCbeta signaling. In contrast, forced expression of C20S/C23S-mutated lck (double-cysteine lck), unable to bind CD4, rescues anti-TCRCbeta proximal signaling and cellular growth. Double-cysteine lck targets lipid rafts, colocalizes with >98% of cellular fyn, and results in a 7-fold increase in basal fyn kinase activity. Coaggregation of CD4 and TCR achieves the same outcome. These results underscore the critical role of lipid rafts in spatially coordinating the interaction between lck and fyn that predicates proximal TCR/CD3 signaling.