By exploring miRNA:mRNA interactions at the single hub level, we observed that many of the mRNA hub genes were predicted to be targeted by multiple miRNAs, thus highlighting the cooperative capacity of these molecules. Cooperative targeting by miRNAs produces synergistic mRNA target repression and enhances the ‘fine-tuning’ capacity of these molecules [54]. In addition, cooperative targeting is thought to increase the cell’s ability to buffer induction of gene expression by external stimuli. We speculate that the cooperative regulation of a single mRNA hub gene by multiple miRNAs provides redundancy within the system to respond to the loss of a critical miRNA:mRNA interaction. In such a case, the presence of additional miRNA target sites ensures that repression of gene expression will be maintained.
