Identification of CMS as a cytosolic adaptor of the human pTα chain involved in pre-TCR function
Identification of CMS as a cytosolic adaptor of the human pTα chain involved in pre-TCR function
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DOI：
10.1182/blood-2007-06-094938
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发表时间：
2007-12-15
期刊：
影响因子：
20.3
通讯作者：
Toribio, Maria L.
中科院分区：
文献类型：
--
作者：
Navarro, Maria N.;Nusspaumer, Gretel;Toribio, Maria L.
T细胞受体β（TCR β）/前TCR α（pT α）前TCR复合物（pre-TCR）发出发育中胸腺细胞的扩增和分化的信号。前TCR的功能特性依赖于其独特的pT α链，这表明特异性细胞内衔接子的参与。然而，pTet相互作用分子仍然未知。在这里，我们确定了一个聚脯氨酸-精氨酸序列在人类pT α细胞质尾，在体外与SH 3结构域的CIN 85/ CMS家族的衔接子，并介导招聘的多蛋白复合物涉及所有（CMS，CIN 85，和CD 2BP 3）的成员。支持这种相互作用的生理相关性，我们发现，1个这样的适配器，CMS，在体内与人pT α相互作用，其表达在人胸腺增殖过程中在前TCR活化的胸腺细胞中选择性上调。在活化后，诱导前TCR聚集，并且CMS和聚合的肌动蛋白同时募集到前TCR活化位点。CMS还通过其C-末端区域与内吞隔室中的肌动蛋白细胞骨架相关联，在那里它与内在化的pT α共定位，以运输至溶酶体降解。值得注意的是，pT α CIN 85/CMS结合基序的缺失损害了前TCR介导的Ca 2+动员和NFAT转录活性，并阻止了由CMS-SH 3 N-末端突变体过表达诱导的活化。这些结果为pT α细胞内衔接子参与前TCR功能提供了第一个分子证据。
The T-cell receptor beta (TCR beta)/pre-TCR alpha (pT alpha) pre-TCR complex (pre-TCR) signals the expansion and differentiation of developing thymocytes. Functional properties of the pre-TCR rely on its unique pT alpha chain, which suggests the participation of specific intracellular adaptors. However, pTet-interacting molecules remain unknown. Here, we identified a polyproline-arginine sequence in the human pT alpha cytoplasmic tail that interacted in vitro with SH3 domains of the CIN85/ CMS family of adaptors, and mediated the recruitment of multiprotein complexes involving all (CMS, CIN85, and CD2BP3) members. Supporting the physiologic relevance of this interaction, we found that 1 such adaptor, CMS, interacted in vivo with human pT alpha, and its expression was selectively up-regulated during human thymopolesis in pre-TCR-activated thymocytes. Upon activation, pre-TCR clustering was induced, and CMS and polymerized actin were simultaneously recruited to the pre-TCR activation site. CMS also associated via its C-terminal region to the actin cytoskeleton in the endocytic compartment, where it colocalized with internalized pT alpha in traffic to lysosomal degradation. Notably, deletion of the pT alpha CIN85/CMS-binding motif impaired pre-TCR-mediated Ca2+ mobilization and NFAT transcriptional activity, and precluded activation induced by overexpression of a CMS-SH3 N-terminal mutant. These results provide the first molecular evidence for a pT alpha intracellular adaptor involved in pre-TCR function.