Mimicry, deception and competition: The life of competing endogenous RNAs

Since their discovery, small regulatory RNAs (sRNAs) were thought to be regulated exclusively at the transcriptional level. However, accumulating data from recent reports indicate that posttranscriptional signals can also modulate the function and stability of sRNAs. One of these posttranscriptional signals are competing endogenous RNAs (ceRNAs). Commonly called RNA sponges, ceRNAs can effectively sequester sRNAs and prevent them from binding their cognate target messenger RNAs (mRNAs). Subsequently, they prevent sRNA-dependent regulation of translation and stability of mRNA targets. While some ceRNAs seem to be expressed constitutively, others are intricately regulated according to environmental conditions. The outcome of ceRNA binding to a sRNA reaches beyond simple sequestration. Various effects observed on sRNA functions extend from reducing transcriptional noise to promote RNA turnover. Here, we present a historical perspective of the discovery of ceRNAs in eukaryotic organisms and mainly focus on the synthesis and function of select, well-described, ceRNAs in bacterial cells. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions Translation > Translation Regulation RNA Turnover and Surveillance > Regulation of RNA Stability.