Identification and validation of miRNA target sites within nontraditional miRNA targets

miRNAs are endogenous small RNAs that regulate gene expression through recognition of complementary RNA sequences. While miRNAs have generally been understood to repress gene expression posttranscriptionally through recognition of 3'-untranslated regions (3'-UTRs) of mRNA transcripts, they have the potential to target additional classes of RNAs. Understanding the expanding pool of potential miRNA targets has been hindered by the lack of tools for predicting target sites within these RNAs. Here, the principles for developing computational algorithms for identifying putative miRNA target sites outside of mRNA are discussed. Laboratory techniques for validating computational miRNA target predictions are described.