ABSTRACT
Objective:To construct eukaryotic inducible expression plasmids pTRE-Tight-CFP-CD11b and pTRE-Tight-YFP-CD18 using Tet-On gene expression system and co-transfect them into Chinese hamster ovary(CHO) cells,so as to achieve the inducible expression of Mac-1-FP.Methods: The eukaryotic expression vectors pTRE-Tight-CFP-CN11b and pTRE-Tight-YFP-CD18 were constructed by recombinant DNA technique.The 2 vectors were co-transfected into CHO cells using liposome to fuse CD11b and CD18: the 2 subunits of Mac-1. Fluorescence microscope was used to observe the cyan fluorescence and the yellow fluorescence of Mac-1-FP.The influence of different levels of Dox(0,0.01, 0.1,0.5,1,2 ?g/ml) on expression levels of CD11b and CD18 in CHO cells was analyzed by RT-PCR and fluorescence intensity analysis.The adhesive rate of CHO-Mac-1-FP cells with ligand ICAM-1 was analyzed before and after PMA(1 ?g/ml) stimulation.Results: The recombinant plasmids of pTRE-Tight-CFP-CD11b and pTRE-Tight-YFP-CD18 were successfully constructed.The cyan and yellow fluorescences were observed in co-transfected CHO cells under fluorescence microscope.The fluorescence intensity of the cells was increased with the increase of Dox concentration.RT-PCR analysis demonstrated that the CD11b and CD18 mRNA increased with the increase of Dox concentration.The adhesive rate of CHO-Mac-1-FP cells with ICAM-1 was increased after PMA stimulation(peaked at 2 h and 4 h after stimulation and decreased afterwards).Conclusion: This study achieves the inducible expression of Mac-1-FP in CHO cells.And Mac-1-FP,like widetype Mac-1,exhibits adhesive activity with ligand ICAM-1,which lays a foundation for studying the consisting dimmer,clustering,conformation and affinity of the ligands of Mac-1 using single molecule spectroscopy and fluorescence resonance energy transfer technique in living cells.