microRNA-binding proteins: specificity and function

microRNA (miRNA) and RNA-binding proteins (RBPs) have been studied widely in post-transcriptional gene regulation. Previous work has focused on defining how miRNA and RBPs modulate target mRNA decay and translation as well as investigating how they interplay each other. Emerging studies indicate that certain RBPs other than the AGO-family proteins directly interact with mature miRNAs. These findings implicate competitive binding of RBPs to target miRNAs, sequestration of miRNAs from AGO, promotion of AGO binding to miRNAs, and transfer of miRNAs from RBPs to AGO. Recent work also indicates that AGO-free cytoplasmic miRNAs establish complexes with novel miRNA-binding proteins (miRBPs). This review covers the recent discovery of novel miRBPs, offering a new perspective on the miRNA-mediated gene silencing mechanism. (C) 2017 Wiley Periodicals, Inc.