Ⅰ类内含子(group I intron)是研究RNAs结构与功能关系的理想元件,在解释RNA折叠理论、催化机制等方面起着重要作用;对其结构与功能关系的研究也因此成为一个非常重要的课题.本研究建立了一个基于卡那霉素抗性进行Ⅰ类内含子结构与功能...Ⅰ类内含子(group I intron)是研究RNAs结构与功能关系的理想元件,在解释RNA折叠理论、催化机制等方面起着重要作用;对其结构与功能关系的研究也因此成为一个非常重要的课题.本研究建立了一个基于卡那霉素抗性进行Ⅰ类内含子结构与功能关系研究系统,将源于海洋蓝细菌Nostoc punctiforme(Npu)核糖核酸还原酶基因(ribonucleotide reductase,Rir)中的1个Ⅰ类内含子插入到pDrive质粒的卡那霉素抗性基因(kanamycin resistance gene,KanR)内构建得pKR12质粒并转化大肠杆菌(E.coli).只有内含子剪接的阳性克隆才能生成KanR蛋白并在Kan抗性平板上生长.结果显示,pKR12转入E.coli后不能在Kan抗性平板上生长,RT-PCR检测仅可见前体带,表明插入到KanR中的Npu Rir内含子没有发生剪接.随后通过易错PCR建立内含子的随机突变库并用Kan抗性筛选进行定向演化,产生有剪接活性的内含子突变体,RT-PCR检测显示剪接发生.由于内含子剪接活性的改变可通过Kan抗性变化在LB平板上得以反映,因此该系统有望成为简单快速地研究Ⅰ类内含子结构与功能关系的有利工具.展开更多
Protein trans-splicing based dual-vector factor VIII （FVIII） gene delivery is adversely affected by less efficiency of protein splicing. We sought to increase the amount of spliced FVIII protein and plasma coagulati...Protein trans-splicing based dual-vector factor VIII （FVIII） gene delivery is adversely affected by less efficiency of protein splicing. We sought to increase the amount of spliced FVIII protein and plasma coagulation activity in dual-vector FVIII transgene in mice by means of strengthening the interaction of inteins, protein splicing elements, thereby facilitating protein trans-splicing. Dual-vector delivery of the FVIII gene in cultured cells showed that replacement of Met226 in the heavy chain and Asp1828 in the light chain with Cys residues could facilitate inter-chain disulfide linking and improve protein trans-splicing, increasing the levels of spliced FVIII protein. In this study, C57BL/6 mice were coadministered dual vectors of intein-fused human FVIII heavy chain and light chain with Cys mutations via portal vein injection into the liver. Forty-eight hours post-injection, plasma was collected and analyzed for FVIII antigen concentration and coagulation activity. These mice showed increased circulating FVIII heavy chain polypeptide （442± 151 ng mL i vs. 305±103 ng mL-1） and coagulation activi- ty （1.46±0.37 IU mL i vs. 0.85±0.23 IU mL-1） compared with control mice co-administered dual vectors expressing the heavy and light chains of wild-type FVIII. Moreover, coagulation activity was similar to that of mice receiving a single vector ex- pressing FVIII （1.79_＋0.59 IU mL-l）. These findings indicate that improving protein trans-splicing by inter-chain disulfide bonding is a promising approach for increasing the efficacy of dual-vector based FVIII gene transfer.展开更多
基金supported by the Natural Science Foundation of Shandong Province (ZR2010CM061)the Scientific Research Foundation from Ministry of Education for Returned Overseas Chinese Scholars (20071108)
文摘Protein trans-splicing based dual-vector factor VIII （FVIII） gene delivery is adversely affected by less efficiency of protein splicing. We sought to increase the amount of spliced FVIII protein and plasma coagulation activity in dual-vector FVIII transgene in mice by means of strengthening the interaction of inteins, protein splicing elements, thereby facilitating protein trans-splicing. Dual-vector delivery of the FVIII gene in cultured cells showed that replacement of Met226 in the heavy chain and Asp1828 in the light chain with Cys residues could facilitate inter-chain disulfide linking and improve protein trans-splicing, increasing the levels of spliced FVIII protein. In this study, C57BL/6 mice were coadministered dual vectors of intein-fused human FVIII heavy chain and light chain with Cys mutations via portal vein injection into the liver. Forty-eight hours post-injection, plasma was collected and analyzed for FVIII antigen concentration and coagulation activity. These mice showed increased circulating FVIII heavy chain polypeptide （442± 151 ng mL i vs. 305±103 ng mL-1） and coagulation activi- ty （1.46±0.37 IU mL i vs. 0.85±0.23 IU mL-1） compared with control mice co-administered dual vectors expressing the heavy and light chains of wild-type FVIII. Moreover, coagulation activity was similar to that of mice receiving a single vector ex- pressing FVIII （1.79_＋0.59 IU mL-l）. These findings indicate that improving protein trans-splicing by inter-chain disulfide bonding is a promising approach for increasing the efficacy of dual-vector based FVIII gene transfer.
