Measuring mRNA translation in neuronal processes and somata by tRNA-FRET

In neurons, the specific spatial and temporal localization of protein synthesis is of great importance for function and survival. In this work, we visualized tRNA and protein synthesis events in fixed and live mouse primary cortical culture using fluorescently-labeled tRNAs. We were able to characterize the distribution and movement of tRNAs in different neuronal sub-compartments and to study their association with the ribosome. We found that tRNA motion in neural processes is lower than in somata and corresponds to patterns of slow transport mechanisms, and that larger tRNA puncta co-localize with translational machinery components and are likely the functional fraction. Furthermore, chemical induction of LTP in culture revealed GluR-dependent biphasic up-regulation of mRNA translation with a similar effect in dendrites and somata. Importantly, measurement of protein synthesis in neurons with high resolutions offers new insights into neuronal function in health and disease states.