人补体调节蛋白DAF、MCP在哺乳动物细胞中的共表达及协同作用研究

Co-expression and Synergic Effect of Human Complement Regulatory Proteins DAF and MCP

利用双启动子构建含人补体调节蛋白DAF和MCP cDNA的双顺反子重组表达载体pcDNA3-DAFMCP-DP,以磷酸钙沉淀法转染NIH3T3细胞,用G418筛选获得NIH3T3 pcDNA3-DAFMCP-DP转化细胞。PCR实验结果显示人补体调节蛋白基因DAF和MCP整合在转化的异源细胞的染色体上。RT-PCR和Western blot印迹实验分别从RNA水平和蛋白质水平证实了人补体调节蛋白分子DAF和MCP在细胞系中皆获得同步表达。检测连续传代30次的NIH3T3 pcDNA3-DAFMCP-DP结果表明人DAF和MCP基因仍稳定整合在细胞基因组中,并未随着传代而丢失,为稳定的转双基因细胞系。补体依赖的细胞毒反应表明,pcDNA3-DAFMCP-DP转染细胞系由于DAF和MCP的共表达获得较DAF或MCP单一表达时更强的保护能力,能更好地抑制人补体依赖的细胞毒作用的发生,保护宿主细胞免受人补体的攻击。以上结果表明,DAF和MCP双基因重组表达载体实现了人补体调节蛋白基因高效转移和高水平共表达,为获得表达多种人补体调节蛋白的理想供体提供了有效策略。而且共表达的DAF和MCP具有协同效应,能更有效地阻止补体激活造成的细胞损伤,在克服超急性排斥反应的基因治疗中具有潜在的临床应用价值。

Recombinant expression vector pcDNA3-DAFMCP-DP containing human membrane complement regulatory proteins （hCRPs） decay accelerating factor （DAF） and membrane cofactor protein （MCP） cDNA was constructed by using two independent promoters. After transfected into NIH3T3 cells by calcium phosphate-DNA precipitate method, NIH3T3 pcDNA3-DAFMCP-DP transfectants were obtained by G418 selection. Extraneous genes integration was identified by PCR. The co-expression of human DAF and MCP at both mRNA and protein levels was confirmed by using RT-PCR and Western blot analysis. Human DAF and MCP cDNA were integrated into NIH3T3 pcDNA3-DAFMCP-DP genomic DNA after continuous 30 times passages, indicating that NIH3T3 pcDNA3-DAFMCP-DP were stable cell lines. Human C-mediated cytolysis assays showed that NIH3T3 cells transfected stably with pcDNA3-DAF, pcDNA3-MCP, and pcDNA3-DAFMCP-DP were protected from C-mediated damage and co-expressed human DAF and MCP provided more excellent protection against C-mediated attack, which was compared with either DAF or MCP alone. These results suggest that the dicistronic vector could improve the efficiency of multi-gene delivery and benefit the synergic effect of human membrane complement regulatory proteins DAF and MCP.