Visualizing RNA granule transport and translation in living neurons

In polarized cells, such as neurons, the synthesis of an mRNA does not ensure its proper cellular expression. Most mature transcripts require the association with RNA-binding proteins, resulting in the formation of RNA granules, which are then transported within the cytoplasm along the cytoskeleton and delivered to their proper subcellular locations, where they can be locally translated. Here we review current microscopy methods that have been developed to visualize RNA granule formation, transport and translation at the single cell level with a special emphasis on the MS2 and SunTag systems. They include the labeling of mRNAs and RNA-binding proteins in living cells or even the detection of newly synthesized proteins in situ.