hTFPI-2的基因克隆表达及生物学性质研究

Cloning,expression and biological characterization of hTFPI-2 gene

目的克隆人组织因子途径抑制物-2(human tissue fact0r pathway inhibitor-2,hTFPI-2)的编码基因,并在大肠杆菌中表达,获得有活性的目的蛋白。方法应用 RT-PCR 法从人胎盘总 RNA 中获得人组织因子途径抑制物-2的编码基因,将该基因片段克隆至原核表达载体 pET19b 中,转化表达宿主 BL21,用异丙基-β-D-硫代半乳糖苷(IPTG)诱导目的蛋白的表达。获得的包涵体经离子交换法进行纯化,并使其在体外进行复性。采用发色底物法测定 hTFPI-2对纤溶酶、胰蛋白酶的抑制作用;明胶酶谱法测定对基质金属蛋白酶(matrix metalloproteinase,MMP)的抑制作用;采用人工基底膜法观察hTFP1-2对纤维肉瘤细胞侵袭能力的影响。结果成功获得了序列完全正确 hTFPI-2的编码基因,hTFP1-2在大肠杆菌中以包涵体的形式获得高效表达,占细菌总蛋白的20%～30%。经纯化、复性后可得到纯度大于90%的目的蛋白。复性后的 hTFPI-2具有抑制胰蛋白酶、纤溶酶、MMP-2和 MMP-9的活性,同时亦具有抑制纤维肉瘤细胞 HT-1080侵袭转移的能力结论采用原核表达系统高效地获得了具有活性的 hTFPI-2。

Objective To clone the human tissue factor pathway inhibitor-2 （hTFPI-2） gene and express it by using prokaryotic expression system. Methods The hTFPI-2 coding region was obtained by RT- PCR from human placenta total RNA. The coding fragment was then inserted into prokaryotic expression vector pET19b and expressed in E. coli BL21 by IPTG induction. The produced inclusion bodies were dissolved by denaturalizing chemicals, purified by ion exchange chromatograph, and refolded in air to form proper disul- fide bonds. Chromogenic and gelatin zymography methods were used to evaluate the inhibiting effects of hTFPI-2 on trypsin, plasmin and MMPs individually. The inhibitory activity of hTFPI-2 on fabrisarcoma was investigated by matrigel. Results The coding fragment of hTFPI-2 was cloned successfully and the protein was expressed as inclusion bodies which account for 20% - 30% of total host protein. The refolded hTFPI-2 could inhibit the invasive ability of fibrisarcoma HT-1080 as well as activity of plasmin, trypsin and MMPs. Conclusions The activated hTFPI-2 is obtained by using prokaryotic expressed system effectively.