Targeting of mRNAs by multiple miRNAs: the next step.

Micro(mi)RNAs are small noncoding RNAs that regulate expression of the majority of the genes in the genome at either the messenger RNA (mRNA) level (by degrading mRNA) or the protein level (by blocking translation). miRNAs are thought to be components of vast regulatory networks. Currently, the field is focused primarily on identifying novel targets of individual miRNAs. This focus is about to undergo a dramatic change. In a new paper by Wu et al. (2010) it is experimentally confirmed that multiple miRNAs target the same gene, suggesting that it is the combination of all these activities that determines the expression of miRNA target genes. This study ushers in a new era of miRNA research that focuses on networks more than on individual connections between miRNA and strongly predicted targets.