摘要
α干扰素为治疗丙型肝炎病毒(HCV)感染的主要药物,但部分患者呈干扰素耐受而不能获得持久的病毒阴转,其可能的原因之一是病毒通过其编码的蛋白(NS5A及E2)抑制干扰素诱导的抗病毒效应分子———双链RNA激活的蛋白激酶(PKR)的活性.而关于PKR是否在IFN-α抗HCV的机理中起抑制作用目前仍有争议.为研究PKR对HCV蛋白合成环节是否有抑制作用,通过构建野生型PKR真核表达载体(pPKRwt)及主要起负性调节作用的缺失突变PKR真核表达载体(pPKRΔ6),并将pPKRwt/pPKRΔ6与HCV复制子RNA同时转染Huh7细胞进行共表达,用Western印迹检测HCV IRES下游的NPTⅡ蛋白表达水平,与转染空载体的对照细胞及单用IFN-α处理的细胞相比较.结果显示:表达PKRwt的细胞中NPTⅡ蛋白水平低于转染空载体的对照细胞,但高于经IFN-α单独处理的细胞;表达PKRΔ6的细胞中NPTⅡ蛋白水平与对照细胞无明显差别,但PKRΔ能部分抵消IFN-α的抑制作用,说明在IFN-α抑制HCV IRES指导的蛋白合成中,PKR有一定的抑制作用,但可能还有其它的PKR非依赖机制参与.
Interferon-α （IFN-α） based therapy is a major strategy to copy with hepatitis C virus （HCV） infection. But there is still a part of patients who could not obtain sustained virological response（SRV） after treated with IFN-α due to the resistance of HCV to IFN-α. One of the explanation is that the NS5A and E2 proteins coded by HCV counteract the double-stranded RNA activated protein kinase （PKR） activity which can lead to viral protein synthesis shutoff. But whether or not PKR play a role in the inhibition of HCV IRES directed viral protein synthesis has the controversial reports currently. To clarify the debate, it was firstly confirmed by Westem blotting that IFN-α treatment led to the increased expression of PKR and eIF2α-P proteins,but inhibitions of NS5A and NPT Ⅱ proteins expression,which were in a dose-dependent manner. Thereafter, the wild type PKR expression vector（pPKRwt）and mutated PKR expression vector（pPKRA6）which contained a deletion of 6 amino acids in the kinase domain and thus has the dominant negative regulatory function were constructed, then pPKRwt /pPKRA6 were cotransfected with HCV replicon RNA into Huh7 cells. The levels of NPT 11 protein directed by HCV IRES were detected by immunoblot and compared with that of the cells transfected with empty vector and the cells treated with IFN-α along. The results showed that NPT 11 protein level in the cells transfected with pPKRwt was lower than that of the cells transfected with empty vector but higher than that of the cells treated with IFN-α. Whereas, the level of NPT 11 protein in the cells transfected with pPKRΔ6 was no significant different from that of the cells transfected with empty vector, but expression of PKRΔ6 could partially rescue the NPT 11 protein synthesis from the inhibition of IFN-α. In conclusion, the results indicated that PKR partially mediated the inhibitory effects of IFN-α on HCV IRES directed viral protein synthesis, but other PKR-independent mechanism might also be involved in the inhibi
出处
《中国生物化学与分子生物学报》
CAS
CSCD
北大核心
2006年第1期24-30,共7页
Chinese Journal of Biochemistry and Molecular Biology
基金
国家自然科学基金资助项目(No.30170844)
国家十五科技攻关计划资助项目(No.2001BA705B06
2004BA718B10)~~
