Comprehensive analysis of human microRNA-mRNA interactome

MicroRNAs play a key role in the regulation of gene expression. A majority of microRNA-mRNA interactions remain unidentified. Despite extensive research, our ability to predict human microRNA-mRNA interactions using computational algorithms remains limited by a complexity of the models for non-canonical interactions, and an abundance of false positive results. Here we present the landscape of microRNA-mRNA human interactions, which we derived from comprehensive analysis of datasets describing direct microRNA-mRNA interactions experimentally defined in HEK293 and Huh7.5 cell lines, along with other available microRNA and mRNA expression data. We have also established a collection of reliable microRNA binding regions that we systematically extracted in course of analysis of 79 CLIP datasets, which is available at http://score.generesearch.ru/services/mirna/ . While only 1-2% of human genes interact with microRNAs, some RNAs display a substantial sponge effect, which is specific to the cell line of study. Some microRNAs are expressed at a very high level, while interacting with only a few mRNAs, thus, indeed, serving as specific gene expression regulators. Other miRNAs might be expressed at relatively low levels, and interact with many mRNAs. Some of the microRNAs might switch between these two classes, depending on cellular context. Results of our study provide an initial resolution into the complex patterns of human microRNA-mRNA interactions.