Spontaneous clustering and tyrosine phosphorylation of NK cell inhibitory receptor induced by ligand binding
Spontaneous clustering and tyrosine phosphorylation of NK cell inhibitory receptor induced by ligand binding
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DOI：
10.4049/jimmunol.170.12.6107
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发表时间：
2003-06-15
影响因子：
4.4
通讯作者：
Long, EO
中科院分区：
文献类型：
--
作者：
Faure, M;Barber, DF;Long, EO
杀伤细胞Ig样受体（KIR）对NK细胞细胞毒性的抑制依赖于KIR中胞质酪氨酸的磷酸化，其募集酪氨酸磷酸酶Src同源蛋白酪氨酸磷酸酶1。尚不清楚KIR（其功能位于酪氨酸激酶下游）如何在结合靶细胞上的HLA I类后成功阻断近端NK细胞活化信号。在这里，我们表明，混合NK细胞与表达HLA-C的昆虫细胞足以诱导KIR的聚集，以及KIR和SHP-1的磷酸化。瞬时磷酸化KIR检测过钒酸盐，蛋白酪氨酸磷酸酶的抑制剂，在次优浓度的存在下。KIR的磷酸化是由配体结合特异性诱导的，因为它仅在HLA-C负载允许KIR结合的肽时才被检测到。KIR磷酸化不依赖于ICAM-1介导的粘附，并且不被肌动蛋白聚合的抑制所阻断，但需要Zn 2+。HLA-C分子间的荧光共振能量转移揭示了KIR结合诱导的紧密的分子间相互作用。这些结果表明KIR的紧密聚集和简单地通过与HLA-C结合诱导的快速KIR磷酸化。KIR在没有粘附和肌动蛋白细胞骨架重排的情况下被磷酸化的独特性质解释了KIR如何在NK-靶细胞接触期间有效地阻断早期激活信号。
Inhibition of NK cell cytotoxicity by killer cell Ig-like receptors (KIR) depends on phosphorylation of cytoplasmic tyrosines in KIR, which recruit tyrosine phosphatase Src homology protein tyrosine phosphatase 1. It is not clear how KIR, whose function lies downstream of a tyrosine kinase, succeeds in blocking proximal NK cell activation signals upon binding HLA class I on target cells. Here we show that mixing NK cells with insect cells expressing HLA-C was sufficient to induce clustering of KIR, and phosphorylation of KIR and SHP-1. Transient phosphorylation of KIR was detected in the presence of pervanadate, an inhibitor of protein tyrosine phosphatases, at suboptimal concentration. Phosphorylation of KIR was specifically induced by ligand binding because it was detected only when HLA-C was loaded with a peptide that permits KIR binding. KIR phosphorylation was not dependent on ICAM-1-mediated adhesion and was not blocked by inhibition of actin polymerization, but required Zn2+. Fluorescence resonance energy transfer between HLA-C molecules revealed close molecular interactions induced by KIR binding. These results demonstrate tight clustering of KIR and rapid KIR phosphorylation induced simply by binding to HLA-C. The unique property of KIR to become phosphorylated in the absence of adhesion and of actin cytoskeleton rearrangement explains how KIR can efficiently block early activation signals during NK-target cell contacts.