Competing endogenous RNAs: A novel microRNA-based mechanism of gene regulation

It has been recently proposed that competitive endogenous RNAs (ceRNAs) sequester microRNAs to regulate mRNA transcripts containing common microRNA recognition elements (MREs). The ceRNA hypothesis stems from the observation that RNA transcripts can communicate with each other through a recently discovered mechanism. MicroRNAs are tiny snippets of RNA (~22nt long) which negatively regulate target gene expression via translational inhibition or transcript cleavage. A microRNA may target many different transcripts, and conversely, individual transcripts may be bound by multiple different microRNAs. In addition to this conventional microRNA → RNA function, it has recently been established that a reversed RNA → microRNA dimension exists, whereby ceRNAs regulate transcript expression via competition for common microRNAs, with microRNA response elements (abbreviated MREs) as the building blocks of this ‘RNA language’. Phenomenological, theoretical, and experimental aspects will be addressed.