Analysis of protein originated in hepatitis C virus NS3 domain

众所周知，在日本，丙型肝炎病毒（HCV）的持续感染与肝细胞癌的关系很高。然而，其机制尚不清楚。已知HCV（肝炎病毒）具有与黄病毒相同的结构。注意到这一点，我们研究了HCV的NS3结构域的功能。我们发现HCV-NS3蛋白是通过转化能力出现的，它对小鼠细胞NIH3T3具有成瘤能力（J.Virol）。， 69: 3893, 1995)。因此，提示HCV- ns3可能对HCV病毒感染的细胞具有致癌作用。然而，这一机制尚不清楚。为此，我们将HCV-NS3和p53两种基因载体同时导入NIH3T3细胞或KN73细胞（储存，源自人肝细胞）。结果发现，HCV-NS3和p53载体引入的细胞，其细胞增殖能力和裸鼠肿瘤形成能力均明显下降。然后，我们筛选了能够与NS3-N端域相互作用的宿主蛋白。通过筛选，我们收集到8个HCV-NS3合并阳性克隆。通过对这些克隆的基因分析，发现克隆中插入了小核RNP （SmD）的mRNA结构域。此外，很明显，该SmD的C端结构域与HCV-NS3放在一起。这些结果提示HCV-NS3的细胞转化机制可能与宿主蛋白密切相关。此外，与HCV-NS3连接的宿主蛋白可能是核蛋白。

It is well known that in Japan the relation between continued infection of hepatitis C virus (HCV) and liver cell cancer is high. However, its mechanism is not clear. HCV (Hepacivirus) is known to show the structure same as Flavivirus. Paying an attention to this point, we have examined the function of a NS3 domain of HCV.And we discovered that HCV-NS3 protein appears by transformation ability, and it has tumor formation ability for mouse cell NIH3T3 (J.Virol., 69 : 3893, 1995). Thus, a possibility that HCV-NS3 shows a carcinogenic function for the HCV virus infected cells was suggested. However, this mechanism is unidentified. To study this, we introduced two genes, HCV-NS3 and p53 vectors, simultaneously, into either NIH3T3 cells or KN73 cells (stocked, human liver cells originated). As a result we found that both the cell-increase ability and the ability of the tumor formation in nude mouse were significantly decreased in the HCV-NS3 and p53 vector introduced cells. Then, we did screening of the host proteins, which are able to show an interacting with NS3-N end domain. By the screening, we gathered 8 clones that were positive HCV-NS3 combination. By the gene analysis of these clones, it was found that domains of mRNA of small-nuclear RNP (SmD) were inserted in the clones. In addition, it became clear that the C end domain of this SmD was put together with HCV-NS3. These results suggest that the cell transformation mechanism of HCV-NS3 may correlate closely with the host proteins. In addition, the host proteins connected with HCV-NS3 are suggested to be nuclear proteins.