The 3′-untranslated region length and AU-rich RNA location modulate RNA–protein interaction and translational control of β2-adrenergic receptor mRNA

Posttranscriptional controls play a major role in β2-adrenergic receptor (β2-AR) expression. We recently reported that β2-AR mRNA translation is suppressed by elements in its 3′-untranslated region (UTR). We also identified T-cell-restricted intracellular antigen-related protein (TIAR) and HuR as prominent AU-rich (ARE) RNA-binding proteins that associate with β2-AR mRNA 3′-UTR. In this study, we identified a poly(U) region at the distal end of the 3′-UTR as critical for TIAR binding to β2-AR mRNA and for translational suppression. Here, we also report that the locations of the poly(U) and ARE sequences within the 3′-UTR are important determinants that control the translation of β2-AR mRNA. Consistent with this finding, a 20-nucleotide ARE RNA from the proximal 3′-UTR that did not inhibit mRNA translation in its native position was able to suppress translation when re-located to the distal 3′-UTR of the receptor mRNA. Immunoprecipitation and polysome profile analysis demonstrated the importance of 3′-UTR length and the ARE RNA location within the 3′-UTR, as key determinants of RNA/protein interactions and translational control of β2-AR mRNA. Further, the importance of 3′-UTR length and ARE location in TIAR and HuR association with mRNA and translational suppression was demonstrated using a chimeric luciferase reporter gene.