Global transcriptome analysis reveals differences between embryonic and adult dorsal root ganglion axonal mRNAs that are implicated in axonal growth and pain

Local protein synthesis in sensory neuron axons is necessary for axonal regeneration with the efficiency of regeneration decreasing with age. Because the full repertoire of transcripts in embryonic and adult rat sensory axons is unknown we asked how the pool of mRNAs dynamically changes during ageing. We isolated mRNA from pure axons and growth cones devoid of non-neuronal or cell body contamination. Genome-wide microarray analysis reveals that a previously unappreciated number of transcripts are localised in sensory axons and that this repertoire changes during development toward adulthood. Embryonic sensory axons are enriched in transcripts encoding cytoskeletal-related proteins with a role in axonal outgrowth. Surprisingly, adult axons are highly enriched in mRNAs encoding immune molecules with a role in nociception. To validate our experimental approach we show that Tubulin-beta3 mRNA is present only in embryonic axons where it is locally synthesised. In summary, we show that the population of axonal mRNAs dynamically changes during development, which may partly contribute to the intrinsic capacity of axons at different ages to regenerate after injury and to modulate pain.

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Gumy LF, Yeo GS, Tung YC, Zivraj KH, Willis D, Coppola G, Lam BY, Twiss JL, Holt CE, Fawcett JW