Expression changes of competitive endogenous RNAs (ceRNAs) have been proposed to influence microRNA (miRNA) activity and thereby regulate other transcripts that contain miRNA binding sites. Here, we find that although miRNA levels define the extent of repression, they do not affect the magnitude of the ceRNA expression change required to observe derepression. Canonical 6-nt sites, which typically mediate modest repression, can nonetheless compete for miRNA binding, with potency ~20% of that observed for canonical 8-nt sites. Sites with extensive additional complementarity can be even more potent, but this occurs predominantly through miRNA degradation rather than competition. Cooperative binding of closely spaced sites for different miRNAs can also increase potency. These results provide quantitative insights into the stoichiometric relationship between miRNA and target abundance, target-site spacing and affinity requirements for ceRNA-mediated gene regulation and specify the unusual circumstances in which ceRNA-mediated gene regulation might be observed. SOURCE: Vikram Agarwal (vagar@uw.edu) -  MIT

Pluto Bioinformatics

GSE76288: Impact of miRNA Levels, Target-Site Complementarity and Cooperativity on ceRNA-Regulated Gene Expression