We’ve all seen those household cleaning commercials on the tele that show a super detergent that cuts through grease, whitens whites, and zaps pet odor effortlessly, so when we first got wind of miRNA sponges a few years back (Nature Methods, August 2007), we remember being interested but skeptical. But, if these vector-driven miRNA inhibitors could really be expressed exactly wherever and whenever researchers wanted, how slick would that be?
Well, a team of researchers out of Harvard Medical School was kind enough to provide us one of the first snapshots into just how useful miRNA sponges may be in Nature Methods this week where they put miRNA sponges (miR-SPs) to work in Drosophila.
Until now, though, these wonders have only worked their magic in cells or transplanted tissues, but these researchers went whole-hog (or “whole-fly”, as it were) by expressing miRNA sponges in intact flies.
The crew put oligos complementary to the target miRNA (with a few mismatches for added stability) downstream of EGFP and five upstream activation sequences in a P-element vector, then crossed the transgenic flies with this vector to other flies with Gal4 driving tissue-specific promoters. After putting these sponges to work they found:
- MiR-SPs were effective in in vivo experiments
- They could control exactly when and where miR-SPs were expressed; a huge challenge for in vivo studies.
- When induced, miR-SPs decreased the levels of specific miRNAs in specific tissues.
- miRNA effectors can be studied by using miR-SPs.
- miR-SPs helped researchers figure out how miR-8 works at neuromuscular junctions.
The researchers also say that many other organisms should be “sponge-worthy”, as long as they are easy to manipulate genetically.
Soak it all in at Nature Methods, November 2009.