Insights into the roles of local translation from the axonal transcriptome

Abstract

Much of our knowledge on the roles of intra-axonal translation derives from the characterization of a small number of individual mRNAs that were found to be localized in axons. However, two recent studies, using large-scale approaches to provide a more comprehensive characterization of the axonal transcriptome, have led to the discovery of thousands of axonal mRNAs. The apparent abundance of mRNAs in axons raises the possibility that local translation has many more functions than previously thought. Here, we review the recent studies that have profiled axonal mRNAs and discuss how the identification of axonal transcripts might point to unappreciated roles for local translation in axons.

Keywords: axonal transcriptome; functions of local mRNA translation; microarray analysis.

Figure 1.

mRNA distribution between axons and growth cones (based on Zivraj et al. [8]). About one-fifth of the axonally localized mRNAs are found in growth cones, but only a small portion of these mRNAs (6%) are enriched in growth cones. These enriched mRNAs might have unique functions in growth cone biology (see text for details).

Figure 2.

A diagram summarizing the intra-cellular pathways that may utilize local translation of axonal mRNAs. Axonal mRNAs may lead to the local production of transmembrane and extracellular proteins (1), proteins that function locally within axons and growth cones (2), that are targeted to mitochondria (3) or ribosomes (4) or that are retrogradely trafficked to the cell body (5).