Messenger RNA

Translation (biology)

Ribosome profiling

Nucleolus

Ribosomal RNA

Biology

Gene

Cytoplasm

Axon

Ribosomal protein

Internal ribosome entry site

Cell biology

Protein biosynthesis

Genetics

Ribosome

Cell Reports

Ribosome assembly occurs mainly in the nucleolus, yet recent studies have revealed robust enrichment and translation of mRNAs encoding many ribosomal proteins (RPs) in axons, far away from neuronal cell bodies. Here, we report a physical and functional interaction between locally synthesized RPs and ribosomes in the axon. We show that axonal RP translation is regulated through a sequence motif, CUIC, that forms an RNA-loop structure in the region immediately upstream of the initiation codon. Using imaging and subcellular proteomics techniques, we show that RPs synthesized in axons join axonal ribosomes in a nucleolus-independent fashion. Inhibition of axonal CUIC-regulated RP translation decreases local translation activity and reduces axon branching in the developing brain, revealing the physiological relevance of axonal RP synthesis in vivo. These results suggest that axonal translation supplies cytoplasmic RPs to maintain/modify local ribosomal function far from the nucleolus in neurons.

On-Site Ribosome Remodeling by Locally Synthesized Ribosomal Proteins in Axons