An Integration of miRNA Target Predictions for the Characterization of Human miRNAs

In the last twenty years it has become clear that post-transcriptional regulation is an elaborate pathway of equal, if not greater, complexity to the one controlling mRNA transcription. Proteins that are involved in transcription, for example, represent as much as 10% of the coding sequence in the genome of metazoans. By contrast, specificity for RNA-mediated silencing-based regulation is conferred by small RNA guides (for example, micro RNAs (miRNAs), small interfering RNAs (siRNAs) and PIWI-interacting RNAs (piRNAs)) that are generated through distinct biogenesis pathways and function in collaboration with specialized effector proteins. Here we shall consider the miRNA class of animal small silencing RNAs. MiRNAs are an ancient innovation among animals: for example, both of the first two miRNAs discovered, lin-4 and let-7, are conserved from nematodes to humans.