Ayu (Plecoglossus altivelis) CD46 isoforms protect the cells from autologous complement attack
Ayu (Plecoglossus altivelis) CD46 isoforms protect the cells from autologous complement attack
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DOI：
10.1016/j.fsi.2020.04.057
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发表时间：
2020-07-01
影响因子：
4.7
通讯作者：
Chen, Jiong
中科院分区：
文献类型：
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作者：
Ma, Wen-Jing;Shi, Yu-Hong;Chen, Jiong
CD 46是一种重要的多功能免疫调节受体。然而，对硬骨鱼类CD 46的功能，特别是不同的CD 46亚型的研究还很有限。本研究从香鱼（Plecoglossus altivelis）中鉴定了3种膜辅因子蛋白（MCP，CD 46）基因亚型，并将其命名为PaCD 46亚型。PaCD 46亚型通过选择性剪接产生，并且全部由四个保守的短共有重复序列（SCR）、可变的富含丝氨酸-苏氨酸-脯氨酸的结构域、跨膜疏水结构域和胞质尾区组成。系统发育分析表明，该亚型与其他鱼类CD 46聚在一起，然后与高等动物CD 46聚在一起。外周血单个核细胞（PBMC）的Western印迹分析显示三个条带，所有这些条带的分子量都比三种PaCD 46亚型的理论值大得多。HEK 293细胞上分别表达3种PaCD 46亚型，Western blotting结果显示与PBMC相似的条带。通过在毕赤酵母中表达获得的PaCD 46亚型的重组胞外结构域显著降低香鱼血清的溶血活性。此外，三种PaCD 46同种型中的每一种分别保护表达同种型的HEK 293细胞。还鉴定了同种型保护自体PBMC免于补体活化。这些结果提供了第一个证据表明PaCD 46亚型可能是补体调节蛋白，以防止补体诱导的自身组织损伤。
CD46 is an important immune regulatory receptor with multiple functions. However, studies on the function of teleost CD46, especially the different CD46 isoforms are limited. In this study, we identified three membrane cofactor protein (MCP, CD46) gene isoforms from ayu (Plecoglossus altivelis) and tentatively named as PaCD46 isoforms. PaCD46 isoforms were generated by alternative splicing and all consisted of four conserved short consensus repeats (SCRs), and the variable serine-threonine-proline-rich domain, transmembrane hydrophobic domain, and cytoplasmic tail. Phylogenetic analysis showed that the isoforms clustered together with other fish CD46 and then with higher animal CD46. Western blotting analysis of peripheral blood mononuclear cells (PBMC) revealed three bands, all of which had much larger molecular weights than the theoretical values of the three PaCD46 isoforms. Moreover, three PaCD46 isoforms were individually expressed on HEK293 cells, and Western blotting showed the similar band profile to that of PBMC. The recombinant extracellular domain of the PaCD46 isoforms, obtained by expression in Pichia pastoris, significantly reduced hemolysis activity of ayu sera. Furthermore, each of the three PaCD46 isoforms respectively protected the HEK293 cells expressing the isoform. The isoforms were also identified for their protection of autologous PBMC from complement activation. These results provided the first evidence that PaCD46 isoforms may be complement regulatory proteins to prevent complement-induced damage to self-tissue.