Translational profiling of retinal ganglion cell optic nerve regeneration in Xenopus laevis

Unlike adult mammals, adult frogs regrow and regenerate their optic nerve following a crush injury. Using Translational Ribosome Affinity Purification (TRAP), a method to isolate mRNAs actively undergoing translation in a target cell population, we have generated a transcriptional profile by RNA-Seq for retinal ganglion cells (RGC) during the period of recovery following an optic nerve injury. Based on bioinformatics analysis using the JGI 9.1 Xenopus laevis gene models, our results reveal a profound shift in the composition of actively translating mRNAs during the early stages of RGC regeneration: as factors involved in cell signaling are rapidly downregulated, and those involved in core metabolism are upregulated. We identified one highly upregulated gene in response to injury, uchl1, which coupled to downregulation of the synucleins (snca, scng), was previously implicated in neurodegenerative diseases. Our injury-screen in Xenopus identified a previously unknown gene, gng8, as being associated with the regenerative process. Our generated online database provides the Xenopus community a valuable resource for the identification of genes involved in the regeneration process to target for future functional studies.