RNA Granules: Functions Within Presynaptic Terminals and Postsynaptic Spines

In neurons, the presence of messenger RNAs (mRNAs), together with the translation machinery at presynaptic terminals or postsynaptic dendritic spines, enables an extrasomatic activity-dependent protein synthesis. The mechanisms of transport, targeting, and release of these mRNAs are beginning to be unveiled, and involve granule-like motile macromolecular ribonucleoparticles termed RNA granules. These complexes contain repressed mRNAs packed together with RNA-binding proteins and ribosomes and travel along microtubules toward synaptic terminals. Upon stimulation, granules are unfolded, allowing local protein synthesis to take place. The presence of the translation apparatus at pre- and postsynaptic subdomains allows rapid delivery of proteins necessary for neuronal development and synaptic plasticity.