The ancient origin of the complement system
The ancient origin of the complement system
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DOI：
10.1038/sj.emboj.7600533
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发表时间：
2005-01-26
期刊：
影响因子：
11.4
通讯作者：
Ding, JL
中科院分区：
文献类型：
--
作者：
Zhu, Y;Thangamani, S;Ding, JL
补体系统一直被认为只起源于后口动物。在这里，我们表明中心补体成分已经存在于原始原生动物谱系中。从“活化石”马蹄蟹（Carcinoscorpius rotundicauda）中分离出脊椎动物补体3 cr3的功能同源物。CrC3类似于人类的C3，并显示出与下后口动物的C3序列最接近的同源性。cr3和血浆凝集素结合广泛的微生物，形成一线先天免疫防御系统。此外，我们还鉴定了CrC2/Bf，这是脊椎动物C2和Bf的同源物，参与C3激活，以及C3受体样序列。此外，还观察到补体介导的细菌吞噬马蹄蟹的血细胞。因此，马蹄蟹作为一种原生动物，揭示了一种原始而复杂的听觉补体防御系统。我们的研究结果表明，在双侧动物的前寒武纪祖先中，关键补体成分和听觉防御机制有一个古老的起源。
The complement system has been thought to originate exclusively in the deuterostomes. Here, we show that the central complement components already existed in the primitive protostome lineage. A functional homolog of vertebrate complement 3, CrC3, has been isolated from a 'living fossil', the horseshoe crab (Carcinoscorpius rotundicauda). CrC3 resembles human C3 and shows closest homology to C3 sequences of lower deuterostomes. CrC3 and plasma lectins bind a wide range of microbes, forming the frontline innate immune defense system. Additionally, we identified CrC2/Bf, a homolog of vertebrate C2 and Bf that participates in C3 activation, and a C3 receptor-like sequence. Furthermore, complement-mediated phagocytosis of bacteria by the hemocytes of horseshoe crab was also observed. Thus, a primitive yet complex opsonic complement defense system is revealed in the horseshoe crab, a protostome species. Our findings demonstrate an ancient origin of the critical complement components and the opsonic defense mechanism in the Precambrian ancestor of bilateral animals.