Here is a nature review paper on RNAi http://www.nature.com/nature/journal...C32422287EA5DE Figure 1 | RNAi-mediated gene silencing.
RNA interference (RNAi) is an apparently ancient defence mechanism against foreign double-stranded RNA (dsRNA
). RNAs of just 22 nucleotides in length, called small interfering RNAs (siRNAs), are snipped from longer dsRNA
chains by an enzyme called Dicer. The antisense strand of the siRNA is used by an RNA-induced silencing complex (RISC) to guide messenger RNA (mRNA) cleavage, so promoting mRNA degradation.
Modified with permission from McManus, M. T. & Sharp, P. A. Gene silencing in mammals by small interfering RNAs. Nature Rev. Genet. 3
, 737-747 (2002) © Macmillian Magazines Ltd. miRNA, microRNA; stRNA, small temporal RNA.
[IMG]file:///E:/DOCUME%7E1/GUS%7E1.GUS/LOCALS%7E1/Temp/moz-screenshot.jpg[/IMG][IMG]file:///E:/DOCUME%7E1/GUS%7E1.GUS/LOCALS%7E1/Temp/moz-screenshot-1.jpg[/IMG][IMG]file:///E:/DOCUME%7E1/GUS%7E1.GUS/LOCALS%7E1/Temp/moz-screenshot-2.jpg[/IMG]http://www.nature.com/horizon/rna/ba...ference_f1.jpg Interestingly, the human siRNAs are there to protect against dsRNAs from viruses, however they THEMSELVES are first dsRNAs to begin with...
Some Interesting Articles in: Specific inhibition of gene expression by small double-stranded RNAs in invertebrate and vertebrate systems Natasha J. Caplen*,, Susan Parrish,§, Farhad Imani¶, Andrew Fire, and Richard A. Morgan*,
PNAS | August 14, 2001 | vol. 98 | no. 17 | 9742-9747
Short interfering RNAs (siRNAs) are double-stranded RNAs of
21-25 nucleotides that have been shown to function as key intermediaries in triggering sequence-specific RNA degradation during posttranscriptional gene silencing in plants and RNA interference in invertebrates. siRNAs have a characteristic structure, with 5'-phosphate/3'-hydroxyl ends and a 2-base 3' overhang on each strand of the duplex. In this study, we present data that synthetic siRNAs can induce gene-specific inhibition of expression in Caenorhabditis elegans
and in cell lines from human
s and mice. In each case, the interference by siRNAs was superior to the inhibition of gene expression mediated by single-stranded antisense oligonucleotides. The siRNAs seem to avoid the well documented nonspecific effects triggered by longer double-stranded RNAs in mammalian cells. These observations may open a path toward the use of siRNAs as a reverse genetic and therapeutic tool in mammalian cells.