Quantitative proteomic strategies for the identification of microRNA targets.

MicroRNAs (miRNAs) are small noncoding RNAs, approximately 22 nucleotides in length, found in diverse organisms. They have emerged in recent years as key regulators of a broad spectrum of cellular functions. miRNAs regulate biological processes by inducing translational inhibition and degradation of their target mRNAs through base pairing to partially or fully complementary sites. In the field of miRNA research, the identification of the targets of individual miRNAs is of utmost importance. Our understanding of the molecular mechanisms by which individual miRNAs modulate cellular functions will remain incomplete until a full set of miRNA targets is identified and validated. Since a miRNA may regulate many of its targets at the translational level without affecting mRNA abundance, proteomic methods are best suited for revealing the full spectrum of miRNA targets. Quantitative proteomics is emerging as a powerful toolbox for identifying miRNA targets and for quantifying the contribution of translational repression by miRNAs. In this review, the authors summarize the quantitative proteomic approaches that have been employed for identification of miRNA targets and discuss current challenges as well as possible ways of overcoming them.