SaRNA

Small activating RNA (saRNA) molecules can induce target gene expression in a phenomenon referred to as dsRNA-induced transcriptional activation (RNAa).

Small double-stranded RNA (dsRNA), such as small interfering RNA (siRNA) and microRNA (miRNA), have been found to be the trigger of an evolutionary conserved mechanism known as RNA interference (RNAi). RNAi invariably leads to gene silencing via remodeling chromatin to thereby suppress transcription, degrading complementary mRNA, or blocking protein translation. Recent discoveries now suggest that dsRNAs may also act as small activating RNAs (saRNA). By targeting sequences in gene promoters, saRNAs readily induce target gene expression in a phenomenon referred to as dsRNA-induced transcriptional activation (RNAa). This discovery expands our knowledge on both the functionality and complexity small RNAs have in regulating gene expression.cite book |author= Li LC|year=2008|chapter=Small RNA-Mediated Gene Activation|title=RNA and the Regulation of Gene Expression: A Hidden Layer of Complexity|publisher=Caister Academic Press|id=ISBN 978-1-904455-25-7] Li LC, et al. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17085592&query_hl=1&itool=pubmed_docsum Small dsRNAs induce transcriptional activation in human cells. Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17337-42.]

Gene activation by RNAa appears to be long-lasting. Induction of gene expression has been seen to last for over ten days. The prolonged effect of RNAa could be attributed to epigenetic changes at dsRNA target sites.

References

Further reading

*Morris KV (2008). RNA and the Regulation of Gene Expression: A Hidden Layer of Complexity. Caister Academic Press ISBN 978-1-904455-25-7
*Tost J (2008). Epigenetics. Caister Academic Press ISBN 978-1-904455-23-3

External links

*Small RNAs Reveal an Activating Side. [http://www.sciencemag.org/cgi/content/full/314/5800/741a Science News of the Week]
*How to get your genes switched on. [http://www.newscientist.com/channel/life/genetics/mg19225780.149-how-to-get-your-genes-switched-on.html New Scientist 16 November 2006]