The role of secondary structures in the functioning of 3 untranslated regions of mRNA: A review of functions of 3 UTRs' secondary structures and hypothetical involvement of secondary structures in cytoplasmic polyadenylation in Drosophila

3 ' untranslated regions (3 ' UTRs) of mRNAs have many functions, including mRNA processing and transport, translational regulation, and mRNA degradation and stability. These different functions require cis-elements in 3 ' UTRs that can be either sequence motifs or RNA structures. Here we review the role of secondary structures in the functioning of 3 ' UTRs and discuss some of the trans-acting factors that interact with these secondary structures in eukaryotic organisms. We propose potential participation of 3 '-UTR secondary structures in cytoplasmic polyadenylation in the model organism Drosophila melanogaster. Because the secondary structures of 3 ' UTRs are essential for post-transcriptional regulation of gene expression, their disruption leads to a wide range of disorders, including cancer and cardiovascular diseases. Trans-acting factors, such as STAU1 and nucleolin, which interact with 3 '-UTR secondary structures of target transcripts, influence the pathogenesis of neurodegenerative diseases and tumor metastasis, suggesting that they are possible therapeutic targets.