Phospholipase Cγ2 Is Critical for Dectin-1-mediated Ca2+ Flux and Cytokine Production in Dendritic Cells
Phospholipase Cγ2 Is Critical for Dectin-1-mediated Ca2+ Flux and Cytokine Production in Dendritic Cells
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DOI：
10.1074/jbc.m806650200
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发表时间：
2009-03-13
影响因子：
4.8
通讯作者：
Lam, Kong-Peng
中科院分区：
文献类型：
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作者：
Xu, Shengli;Huo, Jianxin;Lam, Kong-Peng
Dectin-1是一种C型凝集素，识别真菌细胞壁中的β-葡聚糖，在抗真菌免疫中发挥重要作用。它通过酪氨酸激酶Syk和适配蛋白CARD9来激活核因子-kappa B，导致树突状细胞(DC)产生促炎细胞因子。除此之外，对Dectin-1信号的机制还知之甚少。我们在这里证明了酵母多糖刺激DC触发细胞内钙通量，这种钙通量可以被阻断的抗Dectin-1抗体或用磷脂酶C(PLC)伽马抑制剂U73122预处理细胞而减弱，这表明Dectin-1信号通过PLC伽马途径诱导DC内的钙通量。有趣的是，用与Dectin-1特异结合的颗粒状Curdlan处理DC，会导致PLC Gamma 1和PLC Gamma 2的磷酸化。然而，我们发现PLC Gamma 2是DC中Dectin-1信号转导的关键酶。PLC-γ2基因缺陷的DC具有严重的钙信号损伤，其分泌IL-2、IL-6、IL-10、IL-12、IL-23和肿瘤坏死因子α能力低下。在Dectin-1刺激下，PLC-Gamma-2缺陷的DC也表现出ERK和JNK MAPKs以及AP-1和NFAT转录因子的激活受损。此外，由于CARD9-Bcl10-Malt1复合体的组装缺陷、IKKα/β激活和I kappa Bα降解受损，PLCγ2缺陷的DC在Dectin-1结合时对NF-kappa B的激活也受到损害。因此，我们的数据表明，模式识别受体如Dectin-1可以诱导钙信号转导，而PLC Gamma 2是Dectin-1信号转导途径中的关键角色。
Dectin-1 is a C-type lectin that recognizes beta-glucan in the cell walls of fungi and plays an important role in anti-fungal immunity. It signals via tyrosine kinase Syk and adaptor protein Card9 to activate NF-kappa B leading to proinflammatory cytokine production in dendritic cells (DCs). Other than this, not much else is known of the mechanism of Dectin-1 signaling. We demonstrate here that stimulation of DCs with zymosan triggers an intracellular Ca2+ flux that can be attenuated by a blocking anti-Dectin-1 antibody or by pre-treatment of cells with the phospholipase C( PLC) gamma-inhibitor U73122, suggesting that Dectin-1 signals via a PLC gamma pathway to induce Ca2+ flux in DCs. Interestingly, treatment of DCs with particulate curdlan, which specifically engages Dectin-1, results in the phosphorylation of both PLC gamma 1 and PLC gamma 2. However, we show that PLC gamma 2 is the critical enzyme for Dectin-1 signaling in DCs. PLC gamma 2-deficient DCs have drastic impairment of Ca2+ signaling and are defective in their secretion of interleukin 2 (IL-2), IL-6, IL-10, IL-12, IL-23, and tumor necrosis factor alpha. PLC gamma 2-deficient DCs also exhibit impaired activation of ERK and JNK MAPKs and AP-1 and NFAT transcription factors in response to Dectin-1 stimulation. In addition, PLC gamma 2-deficient DCs are also impaired in their activation of NF-kappa B upon Dectin-1 engagement due to defective assembly of the Card9-Bcl10-Malt1 complex and impaired IKK alpha/beta activation and I kappa B alpha degradation. Thus, our data indicate that pattern recognition receptors such as Dectin-1 could elicit Ca2+ signaling and that PLC gamma 2 is a critical player in the Dectin-1 signal transduction pathway.