Negative regulation of T cell receptor signaling by Siglec-7 (p70/AIRM) and Siglec-9
Negative regulation of T cell receptor signaling by Siglec-7 (p70/AIRM) and Siglec-9
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DOI：
10.1074/jbc.m403538200
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发表时间：
2004-10-08
影响因子：
4.8
通讯作者：
Paulson, JC
中科院分区：
文献类型：
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作者：
Ikehara, Y;Ikehara, SK;Paulson, JC
Siglec-7(p70/airm)和Siglec-9是自然杀伤(NK)细胞和外周T细胞亚群上表达的与CD33相关的Siglecs。与其他抑制性NK细胞受体一样，它们的胞浆结构域含有基于酪氨酸的免疫球蛋白受体家族抑制基序，Siglec-7已被证明对NK细胞的激活具有负性调节作用。根据T细胞上存在这些Siglecs的报道，我们试图确定它们是否能够利用稳定和瞬时转染Siglec-7或Siglec-9的Jurkat T细胞来调节T细胞受体(TCR)信号。在过钒酸盐刺激或TCR参与后，两种Siglecs都表现出更高的酪氨酸磷酸化和SHP-1的募集。Siglec-7和Siglec-9的作用在信号通路的下游事件中也很明显。这两个Siglecs都减少了ZAP-70上Tyr(319)的磷酸化，已知在TCR刺激后上调基因转录方面发挥了关键作用。使用荧光素酶报告基因检测，激活的T细胞核因子(NFAT)的转录活性也相应降低。像所有的Siglecs一样，Siglec-7和Siglec-9识别糖蛋白和糖脂中含有唾液酸的糖链作为配体。Siglec-7(Arg(124))或Siglec-9(Arg(120))配体结合部位保守的Arg突变导致NFAT/荧光素酶转录抑制功能减弱，这表明TCR信号的最佳抑制需要配体结合。综合结果表明，Siglec-7和Siglec-9都能够对TCR信号进行负调控，并且需要结合配体才能达到最佳活性。
Siglec-7 (p70/AIRM) and Siglec-9 are "CD33"-related siglecs expressed on natural killer (NK) cells and subsets of peripheral T cells. Like other inhibitory NK cell receptors, they contain immunoglobulin receptor family tyrosine-based inhibitory motifs in their cytoplasmic domains, and Siglec-7 has been demonstrated to negatively regulate NK cell activation. Based on reports of the presence of these siglecs on T cells, we sought to determine if they are capable of modulating T cell receptor (TCR) signaling using Jurkat T cells stably and transiently transfected with Siglec-7 or Siglec-9. Following either pervanadate stimulation or TCR engagement, both Siglecs exhibited increased tyrosine phosphorylation and recruitment of SHP-1. Effects of Siglec-7 and -9 were also evident in downstream events in the signaling pathway. Both siglecs reduced phosphorylation of Tyr(319) on ZAP-70, known to play a pivotal role in up-regulation of gene transcription following TCR stimulation. There was also a corresponding decreased transcriptional activity of nuclear factor of activated T cells ( NFAT) as determined using a luciferase reporter gene. Like all siglecs, Siglec-7 and -9 recognize sialic acid-containing glycans of glycoproteins and glycolipids as ligands. Mutation of the conserved Arg in the ligand binding site of Siglec-7 (Arg(124)) or Siglec-9 (Arg(120)) resulted in reduced inhibitory function in the NFAT/luciferase transcription assay, suggesting that ligand binding is required for optimal inhibition of TCR signaling. The combined results demonstrate that both Siglec-7 and Siglec-9 are capable of negative regulation of TCR signaling and that ligand binding is required for optimal activity.