A method for the tissue-specific inhibition of microRNAs ― which play a key role in regulating gene expression ― is published online this week in Nature Methods. This method was used to investigate the formation of neuromuscular junctions in the fruit fly and could also be used to study microRNA function in other tissues.
MicroRNAs bind to a partially complementary target sequence of an RNA transcript and thereby either destine the RNA for degradation or prevent its translation into protein. The most effective way to study the role of microRNAs is to eliminate the gene that encodes them, but this is a time- and labor-intensive process.
A quicker alternative is to over-express their short target sequences, termed microRNA sponges, which will soak up the microRNA and move it away from its natural target. David Van Vactor and colleagues designed microRNA sponges in the fruit fly that are expressed at a precise time and in particular tissues of choice during a fly's development to adulthood. The scientists show that their sponges copy the effect of removing the microRNA gene, and they demonstrate that a particular microRNA affects the formation of the neuromuscular junction through its activity in the muscle and not the neurons.
This precise dissection of microRNA-driven gene regulation should also shed light on microRNA function in organisms beyond the fly.