Review of Research Paper on RNA in Mammalian Cells -- Biology

Review of Research Paper: Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells Overview The significance of this experiment is that it shows how siRNA suppresses the expression of genes in different mammalian cells. It was known previous to the experiment that dsRNA can trigger apoptosis in cells- this is an automatic defense mechanism that mammalian cells use to protect against the dsRNA possessed by viruses. The dsRNA can cause RNA interference when it is taken into the cell by a transgene or a virus. The dsRNA is then cleaved by ribonuclease III enzyme into 21-22 nucleotide siRNA's. The siRNA's joins a nuclease complex to form an RNA-induced silencing complex. This complex then cleaves and degrades mRNA. The question was, could transfecting the cell directly with siRNA produce RNA interference? This experiment was performed to test whether siRNA's are capable of RNAi in mammalian cell cultures. (The idea to test gene silencing on mammalian cells sparked from a petunia-darkening experiment.) To do this they synthesized siRNA duplexes against genes that coded for sea pansies and two variants of firefly luciferases. Luciferase is used because it emits light so it's easy to see if the genes are turned on or off, and by what degree. The luciferase activities were recorded 20 hours after transfection and it was seen that the specific inhibition of luciferase was complete, which is similar to the results obtained for dsRNA. In mammalian cells where the reporter genes were more strongly expressed, the ability of the siRNA to completely suppress the gene was reduced. Background Information So, what's with all these petunia flowers anyways? Gene Suppression Within Plants Plant scientists ... ...nderstanding of the significance of genes. Primarily, by silencing a given gene of the genome using a transfected siRNA, geneticists can quantifiably study the properties of the gene and the allele it encodes. This knowledge can then be applied to the pharmaceutical industry to identify "druggable" gene targets. Plants RNAi can be used for multiple purposes in plants. Among the most notable, it can be used to control insect viral vectors and improve the tolerance to pests and stress so that crops do not need to be destroyed regularly by insecticides. It can also cure plants by potentially eliminating toxins and allergens. Finally, RNAi employment can create perfection by extending flowering and fruit setting periods. References Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells published in Nature (Vol. 411, 24 May 2001).