Schematic of the effects of ARE and URM motifs in genes after miRNA transfections. (A) Effect on extent of down-regulation with transfected miRNA target site alone, the attenuation of down-regulation with ARE motifs in addition to the transfected target site, and the enhancement of down-regulation with URM motifs in addition to transfected target sites. Down-regulation is multiplicative, suggesting a synergistic mechanism of URM1 and transfected target sites. (B) Endogenous miRNA targets are more up-regulated after miRNA transfection if they also have ARE stability motifs. Up-regulation mediated by endogenous target sites and ARE motifs is multiplicative when they co-occur in a 3′ UTR, suggesting a synergistic mechanism.
