A-to-I editing of microRNAs: regulating the regulators?

An important epigenetic mechanism in mammals is adenosine deamination, which generates transcriptome variety through the conversion of single adenosines into inosines in RNA molecules. Inosine is interpreted as guanosine by the translational machinery, and when A-to-I RNA editing occurs in the coding region of pre-mRNA molecules this substitution can result in non-synonymous codon changes and subsequent altered protein function. Furthermore, editing can also take place in non-coding RNA molecules, including pri-miRNAs. In this review I intend to give an overview on the interplay between miRNA-mediated control of gene expression and RNA editing, and how editing could impact cellular behavior by influencing mature miRNA expression levels.