Regulation of mRNA Translation in Axons

Axons can extend long distances from the neuronal cell body, and mRNA translation in axons is used to locally generate new proteins in these distal reaches of the neuron’s cytoplasm. Work over the past two decades has shown that axonal mRNA translation occurs in many different organisms and different neuronal systems. The field has progressed substantially over this time, moving from documenting mRNA translation in axons to understanding how axonal mRNA translation is regulated and what the protein products do for the neuron. Translational regulation in axons extends beyond merely controlling activity of the protein synthesis machinery. Transport of mRNAs into axons, stability of the mRNAs within the axons, and sequestration of mRNAs away from the translational machinery each contribute to determining what proteins are generated in axons, as well as when and where those proteins are generated within the axon. It is now known that thousands of different mRNAs can localize into axons. Based on unique responses to different axonal translation regulating stimuli and events, there clearly is specificity for when different mRNA populations are translated. How that specificity is driven is just now beginning to be understood, and studies emerging over the last five years point to multiple mechanisms for imparting specificity for regulation of axonal protein synthesis responses.