MicroRNAs and their variants in an RNA world: Implications for complex interactions and diverse roles in an RNA regulatory network

Abstract

Multiple microRNA (miRNA) variant (isomiR) sequences have been identified at miRNA loci, suggesting that the miRNA sequence is not a single sequence but a series of isomiR sequences with sequence and expression heterogeneities. These isomiRs may be considered a large gene family with diverse expression patterns or a mini-gene cluster with high levels of sequence similarity. Although the isomiRs are diverse and have potentially coordinated relationships in regulatory networks via isomiR–isomiR interactions, they are largely unstudied. External interactions with other RNAs also enrich the cross-talk across different RNA molecules. In the present study, we describe miRNAs/isomiRs and their interactions, and methods and platforms. Interactions with small RNAs may be an internal regulatory pattern and an effective means of achieving synergistic regulation, which provides a new angle to explore the small RNA world.