Features of Complementary Interactions of BmiRNAs with mRNAs of Human Genes

More than three decades have passed since the discovery of miRNAs in human cells, yet many of their biological properties remain poorly understood. The aim of this study was to investigate whether miRNAs can interact with target gene mRNAs through fully complementary base pairing. Using the MirTarget program, we demonstrated that all nucleotides of miRNAs can form fully complementary interactions with nucleotides of target gene mRNAs. A total of 1036 miRNAs, which were identified by Backes et al. and we designated as BmiRNAs and mRNAs from 17,508 human genes, were analyzed, revealing several important characteristics. The vast majority of BmiRNAs were found to bind fully complementarily to the 3′-untranslated regions (3′UTRs) of target gene mRNAs. Many mRNAs contained binding sites (BSs) for multiple BmiRNAs, forming binding site clusters in which BmiRNAs may compete for interaction with the same mRNA. We also identified identical groups of up to four BmiRNAs capable of binding to the mRNAs of different genes. In addition, genes whose mRNAs contained up to eight BmiRNA binding sites were identified. These findings broaden our understanding of the mechanisms by which BmiRNAs regulate human gene expression at the mRNA translation stage and provide new insights into their potential role in post-transcriptional gene regulation.