大鼠凝血因子Ⅶ EGFP-EGF1融合蛋白的表达及其结合功能初步研究

本研究通过融合蛋白EGFP-EGF1的表达,探讨大鼠凝血因子Ⅶ上EGF1片段与组织因子（TF）的结合功能。用RT-PCR方法自大鼠肝脏组织获得EGF1编码区基因并将其插入EGFP原核表达载体中,构建pET28a-EGFP-EGF1融合蛋白表达载体;将该重组质粒转化大肠杆菌BL21中,用IPTG诱导表达EGFP-EGF1融合蛋白;采用亲和层析方法Ni柱纯化融合蛋白,将融合蛋白作用于经脂多糖刺激表达TF的大鼠血管内皮细胞;通过荧光显微镜及流式细胞术观察和检测融合蛋白与细胞结合情况。结果表明：EGFP-EGF1在转化的大肠杆菌中获得高效表达并成功纯化,SDS-PAGE证实分子量约为36kD。荧光显微镜及流式细胞术检测显示该融合蛋白能与内皮细胞膜上的TF结合。结论：大鼠凝血因子Ⅶ上EGF1区可介导FⅦ与TF特异性结合,从而可能为分子靶向抗栓治疗研究提供部分基础。

Expression of Fusion Protein Encoding EGFP-EGF1 of Rat Coagulation Factor Ⅶ and Its Binding Function

This study was aimed at clarification of the function of EGF(1) segment in rat coagulation factor VII with tissue factor (TF) by means of the expression of the fusion protein of EGFP-EGF(1). The DNA fragment encoding EGF(1) was amplified from a rat liver tissue by RT-PCR, and then inserted in an EGFP-procaryotic expression vector to construct the recombinant plasmid pET28a-EGFP-EGF(1) which was introduced into the competent cells of E.coli BL21, then an engineering bacteria strain was obtained which was induced by IPTG to express the fusion protein of EGFP-EGF(1). The fusion protein was purified by chromatography on Ni column, and then acted on the rat hemangioendotheliocytes stimulated with LPS to express TF; the binding of the fusion protein to the hemangioendotheliocytes was detected by means of fluorescence microscopy and flow cytometry. The results indicated that EGFP-EGF(1) was highly expressed in the engineering E.coli strain, and successfully purified, and its molecular mass was confirmed as 36 kD by SDS-PAGE. Fluorescence microscopy and flow cytometry had shown that this fusion protein can bind with the TF on the hemangioendotheliocytes. It is concluded that the EGF(1) region of rat coagulation factor can mediate the specific binding of FVII with TF, so as to lay partly the basis for molecular targeting anti-thrombotic therapy.