RESUMO
A major issue of current virology concerns the characterization of cellular proteins that operate as functional components of the viral multiplication process. RNAi is a powerful tool to elucidate gene functions. In this study three RNAi approaches (transient transfection, stable transduction and inducible RNAi) were assessed to validate human RNA helicase A (RHA) as an essential factor in hepatitis C virus (HCV) replication. It indicated that RHA transient knockdown by synthetic siRNA had no effect on HCV replication, while RHA stable knockdown via lentivector transduction caused cell lethality. The involvement of RHA in HCV replication was verified by an RNAi inducible system that, on the one hand, maintained long-term gene silencing, but on the other hand, alleviated siRNA toxicity during the essential gene silencing. A 21-day follow-up of the response of HCV replication to the presence and absence of RNAi indicated that RHA is a cellular factor involved in the HCV replication process.
Assuntos
RNA Helicases DEAD-box/metabolismo , Inativação Gênica , Hepacivirus/fisiologia , Proteínas de Neoplasias/metabolismo , Replicação Viral , Linhagem Celular , Sobrevivência Celular , RNA Helicases DEAD-box/genética , Técnicas de Silenciamento de Genes , Humanos , Proteínas de Neoplasias/genética , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismoRESUMO
RNA interference (RNAi) is the process of using specific sequences of double-stranded RNA (dsRNA) to knock down the expression level of sequence-homologous genes. Such ability of small interfering RNA (siRNA) in mammalian cells will undoubtedly revolutionize the study of functional genomics, the discovery of drug targets and even the treatment of human diseases. In this review we briefly describe the history of RNAi discovery, the RNAi mechanism and the general guideline for siRNA design as well as various methods for siRNA production and delivery. We also introduce the potential applications of siRNA, inducible siRNA and siRNA library in speeding up basic biomedical research and in acting as potential therapeutic agents for treatment of numerous human diseases.
Assuntos
Interferência de RNA , Animais , Sequência de Bases , Humanos , Plasmídeos , RNA Interferente Pequeno/química , Transcrição GênicaRESUMO
Two types of tetracycline-controlled inducible RNAi expression systems have been developed that generally utilize multiple tetracycline operators (TetOs) or repressor fusion proteins to overcome the siRNA leakiness. Here, we report a novel system that overexpresses the tetracycline repressor (TetR) via a bicistronic construct to control siRNA expression. The high level of TetR expression ensures that the inducible promoter is tightly bound, with minimal basal transcription, allowing for regulation solely dependent on TetR rather than a TetR fusion protein via a more complicated mechanism. At the same time, this system contains only a single TetO, thus minimizing the promoter impairment occurring in existing systems due to the incorporation of multiple TetOs, and maximizing the siRNA expression upon induction. In addition, this system combines all the components required for regulation of siRNA expression into a single lentiviral vector, so that stable cell lines can be generated by a single transduction and selection, with significant reduction in time and cost. Taken together, this all-in-one lentiviral vector with the feature of TetR overexpression provides a unique and more efficient tool for conditional gene knockdown that has wide applications. We have demonstrated the high degree of robustness and versatility of this system as applied to several mammalian cells and xenograft animals.