重组人Jo-1自身抗原的克隆、原核表达及抗原特异性鉴定

Cloning and prokaryotic expression of recombinant Jo-1 antigen and identification of its antigen specificity

目的:旨在获得高纯人Jo-1抗原(即组氨酰-tRNA合成酶)。方法:利用RT-PCR从人胎盘总RNA中获得Jo-1的编码基因,并分别用IMPACT-CN和pMAL系统的pTYB11、pMAL-c质粒,构建了表达载体,转化至大肠杆菌ER2566、BL21。结果:经筛选与鉴定,得到阳性重组子诱导表达后均获得Jo-1融合蛋白。Western blot显示,这两种融合蛋白都具有Jo-1抗原特异性,即仅与含Jo-1抗体的多肌炎和皮肌炎自身免疫病患者血清反应,而与正常人以及188例含有其他自身抗体(分别为RNP阳性、Sm阳性、Ro/La阳性和RNP/Ro阳性)的患者血清均为阴性反应。结论:在两种表达载体中,pMAL-c-Jo-1的表达量超过菌体蛋白的50%,而且以可溶性形式存在,有利于分离纯化,为临床检测创造了条件。

AIM： To obtain highly purified Jo-1 autoantigens. METHODS： The full length of DNA sequence coding for Jo-1 （histidyl-tRNA synthetase） was obtained from hu-man placenta by RT-PCR and then it was inserted into pTYB11 or pMAL-c to construct the expression vectors pTYB11-Jo-1 and pMAL-c-Jo-1. The recombinant plasmids were transformed into ER2566 and BE21 of E. coli, respectively. RESULTS： The fusion Jo-1 antigens were expressed, Western blot analysis demonstrated they responded specifically to anti-Jo-1 antibody from the patients with autoimmune disease polymyositis and dermatomyositis, but did not respond to normal sera and 188 sera containing anti-RNP, Sm, Ro/La or RNP/Ro antibodies from rheumatosis patients. CONCLUSION： The expressed protein of pMAL-c-Jo-1 is soluble, which accounts for more then 50% of total proteins of cells and can be purified by affinity chromatography. The purified proteins can be used as reagents for determining the anti Jo-1 antibody in the serum of patients.