Itsui Y, Sakamoto N, Kurosaki M, Kanazawa N, Tanabe Y, Koyama T, Takeda Y, Nakagawa M, Kakinuma S, Sekine Y, Maekawa S, Enomoto N, Watanabe M
Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
J Viral Hepat. 2006 Oct;13(10):690-700. doi: 10.1111/j.1365-2893.2006.00732.x.
Type-I interferons (IFNs) and the interferon-stimulated genes (ISGs) play a major role in antivirus responses against hepatitis C virus (HCV) infection. In this study, we studied expression profiles of ISGs in cells supporting subgenomic HCV replication (Huh7/Rep), and screened their activities to suppress HCV replication. Real-time PCR analyses showed that the expression levels of 23 ISGs were significantly lower in Huh7/Rep than naive Huh7 cells due to transcriptional suppression of the interferon-stimulated response element (ISRE). Furthermore, the expression level of ISGs was also decreased in the cured Huh7 cells in which replicon had been eliminated (cHuh7), indicating adaptation of the cells to support HCV replication by downregulating ISGs. On the other hand, expression of HCV replicon was significantly suppressed by overexpression of several ISGs including PKR, MxA, IRF-9, GBP-1, IFI-6-16, IFI-27, 25OAS and IRF-1. Knock down of GBP-1, IFI-6-16 and IFI-27 by short hairpin RNA resulted in increase of HCV replication. Thus, we conclude that downregulation of ISG expression is required in the host cells supporting HCV replication and that several ISGs directly suppress HCV replication. The search for ISGs that regulate HCV replication may help to elucidate the cellular antiviral defence mechanisms against HCV infection.
I型干扰素（IFNs）和干扰素刺激基因（ISGs）在针对丙型肝炎病毒（HCV）感染的抗病毒反应中起主要作用。在本研究中，我们研究了支持亚基因组HCV复制的细胞（Huh7/Rep）中ISGs的表达谱，并筛选了它们抑制HCV复制的活性。实时PCR分析表明，由于干扰素刺激反应元件（ISRE）的转录抑制，Huh7/Rep中23种ISGs的表达水平显著低于未处理的Huh7细胞。此外，在已消除复制子的治愈Huh7细胞（cHuh7）中，ISGs的表达水平也降低，这表明细胞通过下调ISGs来适应支持HCV复制。另一方面，包括PKR、MxA、IRF-9、GBP-1、IFI-6-16、IFI-27、25OAS和IRF-1在内的几种ISGs的过表达显著抑制了HCV复制子的表达。通过短发夹RNA敲低GBP-1、IFI-6-16和IFI-27导致HCV复制增加。因此，我们得出结论，支持HCV复制的宿主细胞中需要下调ISG表达，并且几种ISGs直接抑制HCV复制。寻找调节HCV复制的ISGs可能有助于阐明针对HCV感染的细胞抗病毒防御机制。
