Specific, direct amplified microRNA detection with microRNA:Argonaute-2 cleavage (miRACle) beacons

Luby BM & Zheng G
Angewandte Chemie, 2017
DOI: 10.1002/anie.201707366

MicroRNA detection is a valuable method for determining cell identity. Molecular beacons are elegant sensors that can transform intracellular microRNA concentration into a fluorescence intensity. While target binding enhances beacon fluorescence, the degree of enhancement is insufficient for demanding applications. Addition of specialty nucleases can allow target recycling and amplify the signal, but this process complicates the assay. We develop and characterize a novel class of beacons susceptible to the endogenous nuclease Argonaute-2 (Ago2). After purifying the complex via co-immunoprecipitation, microRNA:Ago2 cleavage (miRACle) beacons undergo site- and sequence-specific cleavage, and show a 13-fold fluorescence enhancement distinct over traditional beacons. The system can be adapted to any microRNA sequence, and can cleave nuclease resistant, non-RNA bases, potentially allowing miRACle beacons to be designed for cells without interference from non-specific nucleases.