Anti-inflammatory actions of Syk inhibitors in macrophages involve non-specific inhibition of toll-like receptors-mediated JNK signaling pathway
Anti-inflammatory actions of Syk inhibitors in macrophages involve non-specific inhibition of toll-like receptors-mediated JNK signaling pathway
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DOI：
10.1016/j.molimm.2010.01.008
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发表时间：
2010-04-01
影响因子：
3.6
通讯作者：
Lin, Wan-Wan
中科院分区：
文献类型：
--
作者：
Lin, Ying-Cing;Huang, Duen-Yi;Lin, Wan-Wan
Toll样受体(Toll-like Receptor，TLRs)是模式识别受体的一个重要家族，在先天免疫系统中发挥重要作用。尽管非受体脾酪氨酸激酶(Syk)是基于免疫受体酪氨酸激活基序的免疫受体的关键信号分子，但其在TLRs信号转导中的作用尚不清楚。在此，我们研究了Syk在TLR介导的信号转导和基因调控中的作用。在骨髓来源的巨噬细胞(BMDM)和RAW 264.7巨噬细胞中，TLR3、TLR4和TLR9的特异性配体聚(I：C)、脂多糖和CpG可增加几种促炎细胞因子和介质的基因水平，包括干扰素β、肿瘤坏死因子α、丝裂原活化蛋白2、白介素6、白介素12β、诱导型一氧化氮合酶和环氧合酶-2。Syk抑制剂(SykI)和JNK抑制剂(SP600125)可抑制TLR诱导的基因上调。相应地，我们发现了TLR3、TLR4和TLR9配体诱导Syk和JNK激活的能力，Y519/Y520上Syk自动磷酸化的增加证明了这一点。JNK的磷酸化和这两种蛋白的活性。我们还发现，SykI阻断了TLRs介导的JNK激活，而不是IKK、p38和ERK的激活以及I kappa B的降解。然而，用siRNA方法敲除Syk蛋白后，TLR介导的JNK激活以及iNOS和COX-2蛋白表达的增加没有变化。通过体外激酶实验，我们发现两种商品Syk抑制剂(SykI和BAY61-3606)对JNK活性有直接的抑制作用。这些发现表明，在探讨Syk的生物学作用时，应考虑到SykI对JNK的非选择性作用。(C)2010爱思唯尔有限公司。保留所有权利。
Toll-like receptors (TLRs) are a major family of pattern recognition receptors (PRRs) and play a crucial role in innate immune system. Even though non-receptor spleen tyrosine kinase (Syk) is a key signaling molecule of immunoreceptor tyrosine-based activation motifs-containing immunoreceptors, its role in TLRs signaling is not clearly understood. Herein, we investigated the role of Syk in TLR-mediated signaling and gene regulation. In bone marrow-derived macrophages (BMDMs) and RAW 264.7 macrophages, treatment of poly(I:C), LPS and CpG, which are specific ligands of TLR3, TLR4 and TLR9, respectively, can increase the mRNA levels of several pro-inflammatory cytokines and mediators, including IFN beta, TNF alpha, MIP2, IL-6, IL-12 beta, iNOS and COX-2. The gene upregulation caused by TLR was inhibited by Syk inhibitor (SykI) and JNK inhibitor (SP600125). Accordingly we found the abilities of TLR3, TLR4 and TLR9 ligands to induce Syk and JNK activation, as evidenced by increased Syk autophosphorylation on Y519/Y520. JNK phosphorylation and both kinase activities. We also found that TLRs-mediated JNK activation, but not IKK, p38 and ERK activation as well as I kappa B degradation in (BMDMs) and RAW 264.7 cells, was blocked by SykI. Nevertheless TLR-mediated JNK activation as well as the increased protein expression of iNOS and COX-2 remained unchanged when Syk protein was knockdown by siRNA approach. With in vitro kinase assay we found two commercial Syk inhibitors (SykI, and BAY61-3606) have direct inhibition on JNK activity. These findings demonstrate that the non-selective action of SykI on JNK should be taken into consideration upon using them to explore the biological actions of Syk. (C) 2010 Elsevier Ltd. All rights reserved.