Monday, July 27, 2009

The importance of miRNA

miRNA's, as stated in the latest issue of Nature (460, 466-467 (23 July 2009)) bind in a "sequence-specific manner" to mRNA. Suzuki and Miyazono

Here's where structural knowledge based models of canonical and non-canonical RNA base-pairs and base-pair steps are fundamental. There is practically no knowledge of what miRNA sequence dependence means in terms of three dimensional structure of RNA.
How do miRNA's bend (or deform) depending on canonical and non-canonical sequence?
What role do stacking interactions play in miRNA binding?

It is amazing to see that even though miRNA's were introduced more or less recently into the body of knowledge of cell biology, that is, around 2001 when 3 papers about them were published in science (http://www.sciencemag.org/cgi/content/summary/294/5543/797), when reading nowadays literature they seem to be standard knowledge and present in every other aspect or regulatory mechanisms.

Reminder:
To make mature miRNA's they follow this path:
pri-miRNA --> DROSHA --> pre-miRNA --> DICER --> miRNA

Wednesday, July 1, 2009

Corey D.R., the son of Elias James Corey

Double stranded RNA can interfere gene expression as was shown by Andrew Fire and Craig Mello in 1998.
If Corey is right, gene expression interference would not only happen at the translational level by targeting mRNA's, but it could also happen at the transcriptional level, by interaction of what he calls agRNA's (anti-gene RNA) with DNA promoter regions.
He makes a good case in his article called:

"The Puzzle of RNAs that Target Gene Promoters"
ChemBioChem 2009, 10, 1135 – 1139


I, of course, would like to know the structures of this RNA's.
What is their non-canonical base-pair content?
Are they hairpins?
What difference would it make for gene promoter targeting if the RNA's are dumbell RNA's?