CRD-BP Protects the Coding Region of βTrCP1 mRNA from miR-183-Mediated Degradation

miRNAs are largely known to base pair with the 3'UTR of target mRNAs, downregulating their stability and translation. mRNA of beta TrCP1 ubiquitin ligase is very unstable, but unlike the majority of mRNAs where 3'UTR determines the rate of mRNA turnover, beta TrCP1 mRNA contains cis-acting destabilizing elements within its coding region. Here we show that degradation of mRNA of beta TrCP1 is miRNA dependent and identify miR-183 as a microRNA that interacts with the coding region of beta TrCP1 mRNA. Argonaute2 interacts with the same region of beta TrCP1 mRNA in an miR-183-dependent manner. Inhibition of miR-183 function or disruption of the miR-183-binding site stabilizes beta TrCP1 mRNA and elevates beta TrCP1 levels, resulting in activation of the SCF beta TrCP E3 ubiquitin ligase. We previously showed that the RNA-binding protein CRD-BP binds to the coding region of beta TrCP1 mRNA and stabilizes it. Here we demonstrate that CRD-BP prevents degradation of beta TrCP1 mRNA by attenuating its miR-183-dependent interaction with Ago2.