Synthetic small interfering RNAs (siRNAs) are an indispensable tool to investigate gene function in eukaryotic cells1, 2 and may be used for therapeutic purposes to knock down genes implicated in disease3. Thus far, most synthetic siRNAs have been produced by chemical synthesis. Here we present a method to produce highly potent siRNAs in Escherichia coli. This method relies on ectopic expression of p19, an siRNA-binding protein found in a plant RNA virus4, 5. When expressed in E. coli, p19 stabilizes an ~21-nt siRNA-like species produced by bacterial RNase III. When mammalian cells are transfected by them, siRNAs that were generated in bacteria expressing p19 and a hairpin RNA encoding 200 or more nucleotides of a target gene reproducibly knock down target gene expression by ~90% without immunogenicity or off-target effects. Because bacterially produced siRNAs contain multiple sequences against a target gene, they may be especially useful for suppressing polymorphic cellular or viral genes.
for background information
"Knockdown of RCK/p54 expression by RNAi inhibits proliferation of human colorectal cancer cells in vitro and in vivo."
The researchers above invented a method in which to produce si-RNA's from bacteria. Why is this a major development?
1) siRNA's produced from bacteria(pro-siRNAs) are produced by molecular machinery(RNase III) and produce siRNA's from all reading frames, as well as sense and antisense strands. What does this mean? This creates siRNA mixtures that have have greater mRNA targets that can silence target genes more effectively. In essence, pro-siRNA's are more effective than their synthetically produced counterparts.
2)This method is cheaper and more efficient than synthetic production of siRNA. Methods can be easily modified for large scale production and distribution.
3) This will probably be the future of medicine and is a promising area of research that have far reaching applications in all biological industries.