Evolution of the Molecules Coupling mRNA Transport with Translational Control in Metazoans

Eukaryotes arose from ancestral prokaryotes as a result of profound evolutionary changes at the molecular, metabolic, and morphological levels. These changes resulted in the emergence of novel and more sophisticated levels of cellular architecture. An essential structure of eukaryotes is the cytoskeleton, whose evo- lution from prokaryotic cytoskeleton proteins allowed novel and fundamental processes such as mitosis, meiosis, inheritance of genetic material, and cellular motility to evolve [1–7]. The emergence of the cytoskeleton also led to the evo- lution of motors driving intracellular transport to discrete regions of a cell, and these motors are capable of transporting an amazing variety of different cargos, ranging from vesicles and organelles to a plethora of proteins and RNAs required for most cellular processes [1, 2, 7–10]. mRNA transport coupled with translation emerged as a key process of gene expression that targets protein synthesis to specific compartments of cells. In this process, motors act in concert with the cytoskeleton to assemble, stabilize, and transport mRNAs, and this process is also coupled with the control of translation. During their journey translation of mRNAs is repressed, and it is only activated once the mRNAs reach their final destination [11–15].
In this chapter, we will review recent findings that shed new light on the evo- lution of the molecules involved in translational control of transported mRNAs. To date, regulation of gene expression involving this phenomenon is known for diverse transcripts, and the transport motors as well as diverse proteins involved in this process have been characterized to a good extent. While progress has been made across eukaryotes, we will put special emphasis on the processes described in metazoans.