Protein-tyrosine kinase Syk is required for pathogen engulfment in complement-mediated phagocytosis
Protein-tyrosine kinase Syk is required for pathogen engulfment in complement-mediated phagocytosis
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DOI：
10.1182/blood-2005-09-3616
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发表时间：
2006-06-01
期刊：
影响因子：
20.3
通讯作者：
Yamamura, Hirohei
中科院分区：
文献类型：
--
作者：
Shi, Yuhong;Tohyama, Yumi;Yamamura, Hirohei
在适应性免疫系统中，蛋白酪氨酸激酶Syk在Fcγ受体介导的吞噬过程中起着核心作用。我们在这里展示了Syk在补体介导的吞噬天然免疫中也扮演着重要的角色。巨噬细胞样分化的HL60细胞和C3双向调理酵母多糖构成病原体-吞噬细胞系统。C3二次调理的酵母多糖颗粒迅速附着在细胞上，随后通过补体受体3被吞噬。在这个过程中，Syk被酪氨酸磷酸化并聚集在新生吞噬小体周围。将Syk-siRNA或显性阴性Syk(dN-Syk)转移到HL60细胞，导致吞噬功能受损。用荧光酵母多糖猝灭分析表明，大多数附着的酵母多糖颗粒位于亲本HL60细胞内，而很少被突变细胞摄取。这些数据表明，Syk对于C3双优化酵母多糖的包埋是必需的。在C3bi-酵母多糖诱导的吞噬过程中，肌动蛋白在吞噬小体周围积聚，随后解聚，进而激活RhoA和Vav的酪氨酸磷酸化。在表达Syk-siRNA或dN-Syk的细胞中，包括肌动蛋白重塑在内的这些反应被抑制。我们的结果表明，Syk通过调节肌动蛋白动力学和RhoA激活途径，在补体介导的吞噬过程中发挥着不可或缺的作用，并且这些功能导致吞噬小体的形成和病原体的吞噬。
The protein tyrosine kinase Syk plays a central role in Fc gamma receptor-mediated phagocytosis in the adaptive immune system. We show here that Syk also plays an essential role in complement-mediated phagocytosis in innate immunity. Macrophage-like differentiated HL60 cells and C3bi-opsonized zymosan comprised the pathogen-phagocyte system. C3bi-opsonized zymosan particles promptly attached to the cells and were subsequently engulfed via complement receptor 3. During this process, Syk became tyrosine phosphorylated and accumulated around the nascent phagosomes. The transfer of Syk-siRNA or dominant-negative Syk (DN-Syk) into HL60 cells resulted in impaired phagocytosis. Quenching assays using fluorescent zymosan revealed that most of the attached zymosan particles were located inside parental HL60 cells, whereas few were ingested by the mutant cells. These data indicated that Syk is required for the engulfment of C3bi-opsonized zymosan. During C3bi-zymosan-induced phagocytosis, actin accumulation occurred around phagosomes and was followed by depolymerization, and further RhoA was activated together with tyrosine phosphorylation of Vav. These responses including the actin remodeling were suppressed in Syk-siRNA- or DN-Syk-expressing cells. Our results demonstrated that Syk plays an indispensable role in complement-mediated phagocytosis by regulating both actin dynamics and the RhoA activation pathway and that these functions of Syk lead to phagosome formation and pathogen engulfment.