Research -> RNAa -> FAQs

FAQs about RNAa

  1. What is RNAa?
    RNAa or RNA activation is a novel small RNA-mediated gene regulation mechanism first reported by us [1][2]. RNAa is achieved by targeting carefully selected gene promoter regions using small dsRNAs (21 nt), and such dsRNA molecules are referred to as small activating RNA or saRNA.
  2. What is saRNA?
    saRNA refers to those promoter targeted dsRNAs that can activate sequence-specific gene expression.
  3. In what organisms has RNAa been observed so far?
    RNAa have been demonstrated in different human cells, non-human primate, mouse and rat cell[3], suggesting that RNAa is at least conserved in mammals.
  4. What are the differences between RNAi and RNAa?
    Apparently RNAa is achieved by targeting a gene promoter instead of an mRNA as the classic RNAi is and its end effect is gene activation instead of knockdown. A big difference between these two mechanisms is their kinetics. RNAi effect is know to occur within a couple of hours and disappear 5-7 days following siRNA transfection, while RNAa does not appear until about 48 hrs following transfection and lasts much longer (at least two weeks).
  5. How to achieve optimal RNAa in in vitro transfection experiments?
    First, general guidelines for transfecting dsRNAs into mammalian cells should be followed. We found that this transfection protocol helpful for achieving optimal gene activation. Here are some important tips: 1) Reverse transfection works better than forward transfection (many vendors of transfection reagents provide reverse transfection protocols); 2) Harvest cells for expression analysis at day 4 or day 5 following transfection; 3) At transfection, cell density should be such that at harvest they are not overcrowded.

References:

[1] Small interfering RNA directed transcriptional activation in human cells [Proc Amer Assoc Cancer Res, Volume 46, 2005]
[2] Small dsRNAs induce transcriptional activation in human cells. Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17337-42. Epub 2006 Nov 3.
[3] RNAa Is Conserved in Mammalian Cells. PLoS ONE 2010;5(1): e8848. doi:10.1371/journal.pone.0008848.