Near-Infrared Fluorescence Imaging of miRNA Using a Transmembrane Polypeptide-Based Genetic Reporter.

MicroRNAs (miRNAs) are small noncoding RNAs that play important regulatory roles in multiple biological processes. Many miRNAs exhibit unique expression patterns and are considered as theranostic biomarkers in a variety of human diseases. A reporter system that is capable of imaging miRNA in vivo is crucial for investigating miRNA biology. In the present study, an organic anion-transporting polypeptide 1B3 (OATP1B3)-based genetic switch system is designed and optimized to achieve near-infrared fluorescent imaging of miRNA by the uptake of indocyanine green (ICG) dye. The reporter system, named miR-ON-OB3, is shown to be efficient to regulate the expression of OATP1B3 in mammalian cells. Notably, the results indicate that the system is of high sensitivity for near-infrared fluorescence imaging of both exogenous and endogenous miRNA in mammalian cells. Moreover, the system is proved to be functional for real-time near-infrared fluorescence imaging of miRNA in living mice. This study establishes a novel genetic encoded reporter for near-infrared fluorescence imaging of miRNA, which may provide a potential tool for in vivo imaging of miRNA in clinical applications due to the clinical availability of ICG.