Genomic analysis of the immune gene repertoire of amphioxus reveals extraordinary innate complexity and diversity
Genomic analysis of the immune gene repertoire of amphioxus reveals extraordinary innate complexity and diversity
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DOI：
10.1101/gr.069674.107
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发表时间：
2008-07-01
期刊：
影响因子：
7
通讯作者：
Xu, Anlong
中科院分区：
文献类型：
--
作者：
Huang, Shengfeng;Yuan, Shaochun;Xu, Anlong
据推测，在脊椎动物进化出基于体细胞多样性的适应性免疫之前，先天免疫的种系编码多样性可能已经更加发达。文昌鱼占据脊索动物门的基础位置，因此是脊椎动物免疫进化的重要参考。在这里，我们报告了第一个全面的基因组调查免疫基因库的文昌鱼佛罗里达Branchiostoma。据报道，紫海胆具有其他物种未见的广泛的先天受体库，包括222个toll样受体（TLRs）， 203个NOD/ nalp样受体（NLRs）和218个清道夫受体（SRs）。我们发现文昌鱼基因组包含71个TLR基因模型，118个NLR基因模型和270个SR基因模型。文昌鱼还扩展了其他受体样家族，包括1215种c型凝集素模型，240种LRR和IGcam-containing模型，1363种其他LRR-containing模型，75种C1q-like模型，98种ficolin-like模型，以及数百种含有补体相关结构域的模型。扩增不仅限于受体，还可能扩展到中间信号转导，因为基因组中有58个TIR适配器样模型，36个TRAF模型，44个caspase启动器模型和541个死亡折叠结构域模型。文昌鱼也有一个复杂的肿瘤坏死因子系统和一个复杂的补体系统，这在其他无脊椎动物中是前所未见的。除了基因数量增加外，免疫蛋白的结构域组合也增加了。总之，这项调查表明文昌鱼是一种没有脊椎动物型适应性免疫的物种，具有非凡的先天复杂性和多样性。
It has been speculated that before vertebrates evolved somatic diversity-based adaptive immunity, the germline-encoded diversity of innate immunity may have been more developed. Amphioxus occupies the basal position of the chordate phylum and hence is an important reference to the evolution of vertebrate immunity. Here we report the first comprehensive genomic survey of the immune gene repertoire of the amphioxus Branchiostoma floridae. It has been reported that the purple sea urchin has a vastly expanded innate receptor repertoire not previously seen in other species, which includes 222 toll-like receptors (TLRs), 203 NOD/NALP-like receptors (NLRs), and 218 scavenger receptors (SRs). We discovered that the amphioxus genome contains comparable expansion with 71 TLR gene models, 118 NLR models, and 270 SR models. Amphioxus also expands other receptor-like families, including 1215 C-type lectin models, 240 LRR and IGcam-containing models, 1363 other LRR-containing models, 75 C1q-like models, 98 ficolin-like models, and hundreds of models containing complement-related domains. The expansion is not restricted to receptors but is likely to extend to intermediate signal transducers because there are 58 TIR adapter-like models, 36 TRAF models, 44 initiator caspase models, and 541 death-fold domain-containing models in the genome. Amphioxus also has a sophisticated TNF system and a complicated complement system not previously seen in other invertebrates. Besides the increase of gene number, domain combinations of immune proteins are also increased. Altogether, this survey suggests that the amphioxus, a species without vertebrate-type adaptive immunity, holds extraordinary innate complexity and diversity.