Biointelligence

September 6, 2009

Gene Silencing and RNA Interference

Filed under: Bioinformatics,Computational Biology — Biointelligence: Education,Training & Consultancy Services @ 3:13 am
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RNA interference (RNAi) is a mechanism that inhibits gene expression at the stage of translation or by hindering the transcription of specific genes.It is a way for cells to regulate which genes would be expressed. This amazing phenomenon was first observed in petunias, when a scientist called Rich Jorgensen introduced a pigment-producing gene under the control of a powerful promoter. Instead of the expected deep purple color in the petunia, the result was a mixture of variegated and white petunias.

RNAi targets include RNA from viruses and transposons (significant for some forms of innate immune response), and also plays a role in regulating development and genome maintenance. Small interfering RNA strands (siRNA) are key to the RNAi process, and have complementary nucleotide sequences to the targeted RNA strand. Specific RNAi pathway proteins are guided by the siRNA to the targeted messenger RNA (mRNA), where they “cleave” the target, breaking it down into smaller portions that can no longer be translated into protein. A type of RNA transcribed from the genome itself, microRNA (miRNA), works in the same way

 Click to view a flash presentation of RNA Interference on nature
http://www.nature.com/focus/rnai/animations/animation/ui_main.swf
Why do we need to shutdown the production of some genes?

Scientists have been interested in the ability to shut down genes, so that observing the effect of turning down a gene can be observed on an organism, giving clues about the function of the gene.
The ability to shut off the genes, may also result in developing new treatments for diseases by turning down the harmful protein producing gene.

Today, the use of RNA interference for biotechnological and therapeutic purposes is a hot research area. RNA interference used to selectively suppress desired genes is a form of genetic engineering. Imagine curing or making progress towards a cure for AIDS, hepatitis, and the flu – all through selectively suppressing the expression of viral genomes. Fully utilizing RNA interference, we might be able to create cotton seeds without poison — they possess great amounts of protein but natural cotton seeds are poisonous — tobacco without carcinogens, and plants with extreme resistance to crop-destroying viruses. RNA interference is a valuable method in the biotechnological toolbox which will continue ushering in the biotech revolution for the 21st century.

A nice article on RNAi can be found at:
http://www.pbs.org/wgbh/nova/sciencenow/3210/02.html