新型穿孔蛋白LPFP介导的可变淋巴细胞受体/补体依赖的细胞毒作用及机制研究

原始无颌脊椎动物七鳃鳗是研究适应性免疫系统起源和进化的理想模式动物，拥有一套不同于免疫球蛋白的特殊适应性免疫系统--可变淋巴细胞受体(variable lymphocyte receptor，VLR)。在前期研究中我们发现VLR可激活补体系统产生细胞毒作用，导致靶细胞强烈的杀伤效应。但其终末杀伤效应分子尚不清楚。通过透射电镜和质谱技术，我们在杀伤后的靶细胞膜上发现了一种新的穿孔蛋白LPFP。该蛋白有典型的穿孔结构域，其功能可能类似于穿孔素或补体膜攻击复合物，是七鳃鳗抵御外来微生物或体内异常突变细胞的强有力武器。本项目旨在探索LPFP在靶细胞表面形成穿孔蛋白复合物的分子机制；阐明该细胞毒作用中穿孔蛋白LPFP与VLR、补体分子间的相互协同作用；深入探讨LPFP介导的VLR/补体依赖的细胞毒作用机制。该研究为进一步研究适应性免疫系统的起源及进化提供线索。

Lamprey, the primitive jawless vertebrate, uses variable lymphocyte receptor (VLR) as alternative adaptive immune system instead of Ig-based receptors used in jawed vertebrates. Our previous study has shown that lamprey possessed a distinctive complement pathway activated by VLR, resulting in target cells lysis and ultimate disruption of cell wall integrity. However, it remains unknown as to what key effector molecules may implement the lysis of target cells in the final step of the cytotoxicity. By means of transmission electron microscopy and protein mass spectrometry, a novel lamprey pore-forming protein (LPFP) with a pore-forming domain was identified on the surface of the target cells killed by lamprey antisera. The LPFP may be similar to C9 in function and acts as defensive weapons against exogenous pathogens or transformed tumor cells in lamprey. Our object is to identify the relationship between LPFP, VLR and complements, and to clarify its cytolytic mechanism against target cells, and search a clue of the origin and evolution of adaptive immune system in lamprey.