c-Cbl-mediated regulation of LAT-nucleated signaling complexes
c-Cbl-mediated regulation of LAT-nucleated signaling complexes
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DOI：
10.1128/mcb.00467-07
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发表时间：
2007-12-01
影响因子：
5.3
通讯作者：
Samelson, Lawrence E.
中科院分区：
文献类型：
--
作者：
Balagopalan, Lakshmi;Barr, Valarie A.;Samelson, Lawrence E.
T细胞受体（TCR）的接合导致多种信号传导分子与TCR快速募集成簇。在受体活化后，衔接子LAT和SLP-76（可视化为用黄色荧光蛋白标记的嵌合蛋白）与TCR瞬时缔合，然后快速解离。以前，我们证明，招募到信号簇后，SLP-76是内吞囊泡通过脂筏依赖性途径，需要的内吞机制与泛素化蛋白的相互作用。在这项研究中，我们专注于LAT，并证明含有这种适配器的信号簇被内化到不同的细胞内隔室，并在TCR激活后迅速消散。LAT的内化在表达在RING结构域中突变的泛素连接酶c-Cbl的版本的细胞中和来自缺乏c-Cbl的小鼠的T细胞中被抑制。此外，c-Cbl RING突变体形式抑制LAT泛素化并引起细胞LAT水平以及磷酸化LAT的基础和TCR诱导水平的增加。总的来说，这些数据表明，在TCR刺激后快速形成信号复合物后，c-Cbl活性参与了活化信号分子亚组的内化和可能的下调。
The engagement of the T-cell receptor (TCR) causes the rapid recruitment of multiple signaling molecules into clusters with the TCR. Upon receptor activation, the adapters LAT and SLP-76, visualized as chimeric proteins tagged with yellow fluorescent protein, transiently associate with and then rapidly dissociate from the TCR. Previously, we demonstrated that after recruitment into signaling clusters, SLP-76 is endocytosed in vesicles via a lipid raft-dependent pathway that requires the interaction of the endocytic machinery with ubiquitylated proteins. In this study, we focus on LAT and demonstrate that signaling clusters containing this adapter are internalized into distinct intracellular compartments and dissipate rapidly upon TCR activation. The internalization of LAT was inhibited in cells expressing versions of the ubiquitin ligase c-Cbl mutated in the RING domain and in T cells from mice lacking c-Cbl. Moreover, c-Cbl RING mutant forms suppressed LAT ubiquitylation and caused an increase in cellular LAT levels, as well as basal and TCR-induced levels of phosphorylated LAT. Collectively, these data indicate that following the rapid formation of signaling complexes upon TCR stimulation, c-Cbl activity is involved in the internalization and possible downregulation of a subset of activated signaling molecules.