SURVEY AND SUMMARY Experimental strategies for microRNA target identification

MicroRNAs (miRNAs) are important regulators of eukaryotic gene expression in most biological processes. They act by guiding the RNAi-induced silencing complex (RISC) to partially complementary sequences in target mRNAs to suppress gene ex-pression by a combination of translation inhibition and mRNA decay. The commonly accepted mech-anism of miRNA targeting in animals involves an interaction between the 50-end of the miRNA called the ‘seed region ’ and the 30 untranslated region (30-UTR) of the mRNA. Many target prediction algo-rithms are based around such a model, though increasing evidence demonstrates that targeting can also be mediated through sites other than the 30-UTR and that seed region base pairing is not always required. The power and validity of such in silico data can be therefore hindered by the simplified rules used to represent targeting inter-actions. Experimentation is essential to identify genuine miRNA targets, however many experimen-tal modalities exist and their limitations need to be understood. This review summarizes and critiques the existing experimental techniques for miRNA target identification