Advances in approaches for the quantitative detection of microRNAs

MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs that play an important role in the control of developmental process of different cells by negative regulation of protein-coding gene expression. Analyzing miRNA expression in tissues or cells can supply valuable information for investigating the biological function of these molecules. Recently, researchers had proposed a number of approaches for analyzing the differences of miRNA expression among different physiological or pathological conditions, and found that aberrant expression of miRNA was related to cancers, neurological disorders and heart diseases, etc. This review focuses on newly developed strategies for miRNA quantification, and elucidates in detail the probe-hybridization based methods including Northern blotting, microarray, gold nanoparticle labelling, and splinted ligation with radioactive labels. The amplification-based methods including quantitative PCR, rolling cycle amplification, invader assay, and the next generation sequencing methods were also discussed. The advantages and disadvantages of these methods were compared.