3′-UTRs and the Control of Protein Expression in Space and Time

The noncoding elements of an mRNA influence multiple aspects of its fate. For example, 3′-UTRs serve as physical and sequence-based information hubs that direct the time, place, and level of translation of the protein encoded in cis, but often also have additional roles in trans. Understanding the information content of 3′-UTRs has been a challenge. Bioinformatic searches for motifs, such as those that encode the polyadenylation signal or microRNA seed regions, are simple enough, but rarely do these inferred positions in genomes correlate well with the actual sites chosen by the relevant nanomachines in living cells. This is almost certainly due to three-dimensional complexity of RNA, the physical states of which are recognized by RNA-binding proteins that serve to read and interpret the information content. Here, we follow the 3′-UTR-mediated posttranscriptional metabolism of mRNA in the germline of the nematode worm Caenorhabditis elegans. While many areas still require the clarification only detailed fundamental research can provide, this model system can serve as a basis of 3′-mediated regulatory control for elaboration in more complex metazoan systems.