Kexiao Zheng

Label-free high-throughput microRNA expression profiling from total RNA

MicroRNAs (miRNAs) are key biological regulators and promising disease markers whose detection technologies hold great potentials in advancing fundamental research and medical diagnostics. Currently, miRNAs in biological samples have to be labeled before being applied to most high-throughput assays. Although effective, these labeling-based approaches are usually labor-intensive, time-consuming and liable to bias. Besides, the cross-hybridization of co-existing miRNA precursors (pre-miRNAs) is not adequately addressed in most assays that use total RNA as input. Here, we present a hybridization-triggered fluorescence strategy for label-free, microarray-based high-throughput miRNA expression profiling. The total RNA is directly applied to the microarray with a short fluorophore-linked oligonucleotide Universal Tag which can be selectively captured by the target-bound probes via base-stacking effects. This Stacking-Hybridized Universal Tag (SHUT) assay has been successfully used to analyze as little as 100 ng total RNA from human tissues, and found to be highly specific to homogenous miRNAs. Superb discrimination toward single-base mismatch at the 5′ or 3′ end has been demonstrated. Importantly, the pre-miRNAs generated negligible signals, validating the direct use of total RNA.

A reverse transcription-free real-time PCR assay for rapid miRNAs quantification based on effects of base stacking.

A rapid and reverse transcription-free real-time PCR microRNA assay was developed based on effects of base stacking. This microRNA assay has been shown to be highly specific to homogenous miRNAs, and the procedure can be completed within 30 min starting from total RNA.