Complete complementarity between miRNA:mRNA pairs is rare in mammals, but as little as a 6 bp match with the target mRNA can be sufficient to suppress gene expression ( 1–4). MicroRNAs (miRNAs) control gene expression post-transcriptionally by binding to complementary sequences in target mRNAs, thereby guiding the effector proteins of RNAi-induced silencing complex (RISC) into close proximity with the mRNA. This review summarizes and critiques the existing experimental techniques for miRNA target identification. Experimentation is essential to identify genuine miRNA targets, however many experimental modalities exist and their limitations need to be understood. The power and validity of such in silico data can be therefore hindered by the simplified rules used to represent targeting interactions. Many target prediction algorithms are based around such a model, though increasing evidence demonstrates that targeting can also be mediated through sites other than the 3′-UTR and that seed region base pairing is not always required. The commonly accepted mechanism of miRNA targeting in animals involves an interaction between the 5′-end of the miRNA called the ‘seed region’ and the 3′ untranslated region (3′-UTR) of the mRNA.

They act by guiding the RNAi-induced silencing complex (RISC) to partially complementary sequences in target mRNAs to suppress gene expression by a combination of translation inhibition and mRNA decay. MicroRNAs (miRNAs) are important regulators of eukaryotic gene expression in most biological processes.

The Way Backwards by R.P. Lister