Bachelor Degree of Clinical Medicine, Tongji Medical College, Huazhong University of Science and Technology,
P.R. China, 2004
Our previous results showed that specific siRNA knock down woodchuck hepatitis virus (WHV) replication and transcripts lead to an up-regulation of interferon stimulated genes (ISGs). The current hypothesis is that the induction of ISGs is a result of recognition of cleaved products of viral RNA by specific cellular sensors, similar to the case of RNase L-induced IFN-beta production. We investigated whether RIG-I / MDA5, PKR, and TLR-3/7 are involved in the RNAi-mediated ISGs up-regulation. In primary murine hepatocytes from WHV transgenic mice, WHV-specific siRNA siWHx decreased more than 50% of WHV transcripts and led to MxA up-regulation by about 30 fold. Similarly, siRNA targeting mouse beta-actin reduced the amount of beta-actin mRNA and also induced upregulation of MxA expression though to a less extent. The inhibitors of PKR (2-AP) and TLR3, 7/8, 9 (Chloroquine) could block the RNAi-mediated induction of MxA expression, suggesting a significant role of PKR and TLR3, 7/8 in the process. Furthermore, Western blot revealed that siWHx treatment lead to increase in PKR phosphorylation. The nuclear translocation of IRF3 was also observed in siWHx treated PMHs, consistent with the potential role of IRF3 pathway in the RNAi-directed ISG induction. In conclusion, we demonstrated that specific siRNAs were able to enhance antiviral immune responses in the dependence on the specific cellular signaling pathways. This effect of siRNA may facilitate the immunotherapy and lead to an enhanced antiviral activity in vivo.
1st supervisor: PD Dr. Mengji Lu
2nd supervisor: Prof. Dr. Johannes Bode
Institute: Department of Virology, University Hospital Essen, University of Duisburg-Essen
Telephone: +49 (0)201 - 723 - 3540
E-mail: xiaoyong.zhang@msn.com |