Federation of American Scientists Case Studies in Dual Use Biological Research Module 5.0: Antibiotic Resistance Case Study
Topic: History of Antibiotics

Intentionally introduced dsRNA must first be processed into small interfering RNAs (siRNAs) which are 22nt in length and analogous to miRNA. Fire and Mello directly injected dsRNA into a nematode and saw a response, but sophisticated mechanisms targeting the long RNA duplex made it ineffective in mammalian cells.

In 2003, Gregory Hannon and coworkers reported in Nature Genetics a very successful method to apply RNAi to an in vivo mammalian system. They developed a system of short hairpin RNAs (shRNAs) expressed from viral vectors whose stem-loop structure allowed them to effectively enter the miRNA pathway in the same way as pre-miRNA. In order to test the efficacy of shRNAs in mice, the authors targeted Trp53, a previously identified tumor suppressor gene. In transgenic mice, the deletion or inactivation of Trp53 will eliminate p53 expression and accelerate tumor formation. This approach represents a straightforward loss-of-function experiment to compare gene silencing by shRNA to standard gene deletions known as knockouts.

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Topic History of RNAi Genetic Control in Mice Implications Implications References Home