High-throughput microRNA target screening: miR-122 case study

Introduction MicroRNAs (miRNAs) are important regulators of gene expression and have been shown to play a role in numerous biological processes such as cellular signaling (1), cell differentiation, growth, development, and apoptosis (2). Mutations and improper regulation of miRNAs have been linked to a variety of physiological disorders such as cancer and heart disease (3,4). In animals, miRNAs are usually complementary to one or more a sites in the 3’UTRs of specific genes. Although current computational predictions of miRNA-UTR interactions provide important guidance for experimental analysis of miRNAs, little functional data exists on which to train prediction algorithms. Genome-wide transcript analysis can identify candidate target transcripts but cannot measure both the changes in a transcript’s stability or translational efficiency attributable to miRNAs. We have created a genome-wide library of human 3’UTR-luciferase reporter constructs to enable researchers to screen thousands of potential miRNA targets in a high throughput fashion. Using this strategy, we sought to identify new targets of miR-122, an important regulator of cholesterol and fatty-acid metabolism in liver that has been suggested as a therapeutic target for metabolic disease (5).