重组跨膜型人CD55分子在小鼠NIH3T3细胞上的表达及其补体溶破保护功能的研究

目的 :在小鼠NIH3T3细胞转染表达人天然GPI锚固型CD5 5和重组跨膜型CD5 5 TM分子 ,观察比较它们对人补体溶破异源细胞的抑制功能。方法 :将带有CD5 5cDNA、CD5 5 TMcDNA的重组逆病毒表达质粒CD5 5 pLXSN、CD5 5TM pLXSN经脂质体法转染PA317细胞 ,用病毒上清感染小鼠成纤维母细胞NIH3T3。经G418加压筛选 ,利用FACS检测获得表达CD5 5和CD5 5 TM分子的阳性细胞克隆 ,通过MTT比色法比较两种分子对人血清补体溶破细胞的抑制功能有无差别。结果 :细胞转染筛选获得多个表达跨膜型人CD5 5分子的NIH3T3细胞克隆 ,补体杀伤试验证实其具有抑制人补体溶破的功能 ,且两种分子的补体抑制功能无明显差异。结论 :成功地建立了稳定表达天然CD5 5、跨膜型CD5 5分子的小鼠NIH3T3细胞 ,证实其表达的GPI型CD5 5分子和CD5 5TM分子均具有抑制人补体溶破细胞的功能 ,为进一步探讨应用跨膜型的CD5 5分子对PNH进行基因治疗奠定了基础。

The expression of human CD55 and CD55-TM molecules in mouse fibroblasts cell line NIH3T3 and their function in complement lysis restriction

Objective:To express the GPI-anchored CD55 and recombinant transmembrane form CD55 molecules on mouse fibroblasts cell line NIH3T3, and compare their inhibitory function of complement lysis.Methods:In previous study,had constructed the transmembrane form CD55 (CD55-TM) cDNA by linking the extracellular portion of CD55 to the transmembrane and cytoplasmic domains of MCP, and then subcloned into retroviral vector pLXSN. In this experiment,had transfected recombinant CD55-TM and GPI anchored CD55 into PA317 packaging cell to generate stable virus-producing cell lines. And then, mouse fibroblasts cell line NIH3T3 was infected with the virus containing CD55, recombinant CD55-TM or pLXSN alone. The expression of these molecules on NIH3T3 cells was detected by FACS analysis. Complement killing assay was carried out using MTT colorimetric method.Results:FACS analysis showed that both CD55 and its TM version were expressed stably on NIH3T3 cells. Both kinds of CD55 molecules can efficiently protect the NIH3T3 cells from complement mediated lysis and there is no significant difference between them. Conclusion:These data showed that both GPI-anchored CD55 and its TM version can normally expressed on NIH3T3 cells and both can protect the NIH3T3 cells from human complement mediated lysis. These results confirmed the feasibility of TM CD55 based gene therapy could be used for PNH, and also provided an excellent model for the study of signal transduction mechanisms mediated by GPI-anchored protein.