Rab35 and its GAP EPI64C in T cells regulate receptor recycling and immunological synapse formation
Rab35 and its GAP EPI64C in T cells regulate receptor recycling and immunological synapse formation
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DOI：
10.1074/jbc.m800056200
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发表时间：
2008-06-27
影响因子：
4.8
通讯作者：
Shaw, Stephen
中科院分区：
文献类型：
--
作者：
Patino-Lopez, Genaro;Dong, Xiaoyun;Shaw, Stephen
在识别抗原后，T细胞受体（TCR/CD3）及其他信号分子会在T细胞与抗原呈递细胞之间一个特化的接触位点，即免疫突触（IS）处富集。这种富集通过包括从循环内体进行极化分泌等机制实现，但调控这一过程的Rabs蛋白和RabGAPs蛋白尚不清楚。EPI64C（TBC1D10C）是一种特性未明的候选RabGAP蛋白，我们通过质谱分析发现其在人外周血T细胞中含量丰富，且在造血细胞中优先表达。基于体外Rab35特异性GAP活性及转染实验结果，EPI64C是一种Rab35 - GAP。在Jurkat T细胞中，EPI64C和Rab35显性负性（DN）构建体均会损害转铁蛋白从循环途径输出，并诱导出现由转铁蛋白受体、TCR以及与TCR极化分泌相关的SNAREs蛋白标记的大液泡。Rab35定位于质膜及细胞内囊泡，在这些部位它与转铁蛋白受体（TfR）及TCR大量共定位。Rab35被强烈招募至免疫突触。转染Rab35 - DN或EPI64C以及敲低EPI64C均会损害细胞结合物的形成。Rab35 - DN会损害TCR在免疫突触处的富集。因此，EPI64C和Rab35调节T细胞中的一种循环途径，并有助于免疫突触的形成，很可能是通过参与TCR向免疫突触的转运来实现的。
Upon antigen recognition, T-cell receptor (TCR/CD3) and other signaling molecules become enriched in a specialized contact site between the T cell and antigen-presenting cell, i.e. the immunological synapse (IS). Enrichment occurs via mechanisms that include polarized secretion from recycling endosomes, but the Rabs and RabGAPs that regulate this are unknown. EPI64C (TBC1D10C) is an uncharacterized candidate RabGAP we identified by mass spectrometry as abundant in human peripheral blood T cells that is preferentially expressed in hematopoietic cells. EPI64C is a Rab35-GAP based both on in vitro Rab35-specific GAP activity and findings in transfection assays. EPI64C and Rab35 dominant negative (DN) constructs each impaired transferrin export from a recycling pathway in Jurkat T-cells and induced large vacuoles marked by transferrin receptor, TCR, and SNAREs implicated in TCR-polarized secretion. Rab35 localized to the plasma membrane and to intracellular vesicles where it substantially colocalized with TfR and with TCR. Rab35 was strongly recruited to the IS. Conjugate formation was impaired by transfection with Rab35-DN or EPI64C and by EPI64C knock down. TCR enrichment at the IS was impaired by Rab35-DN. Thus, EPI64C and Rab35 regulate a recycling pathway in T cells and contribute to IS formation, most likely by participating in TCR transport to the IS.