Elucidating Schwann cell reprogramming

Abstract

The peripheral nervous system, unlike the central nervous system, has an exceptional capacity for regeneration following injury. This is due to the remarkable plasticity of the Schwann cells (SC), which are able to reprogramme, following injury, to a progenitor like cell which facilitates peripheral nerve repair. Current knowledge on the molecular basis of this reprogramming is incomplete and we are lacking a global overview of the transcriptional events that occur in SC following nerve injury and how these change over time. We aimed to characterise transcriptional changes in the SC, over time, following nerve injury using RNAseq. We also aimed to develop an in vitro dedifferentiation assay to use as a screening tool to asses potential key genes found using RNAseq. We developed a method of reliably extracting good quality, SC specific, RNA from the sciatic nerve of mice using fluorescence activated cell sorting. We performed RNAseq on SC from intact nerves and from the distal stump of nerves 6 days post transection. We validated this method by confirming differential expression of genes known to be up and downregulated following nerve injury, using RNAseq data. In analysing the RNAseq data we identified several potentially exciting, novel key molecular players in SC reprogramming, namely Myc and Runt-related transcription factor 1. We also developed an in vitro dedifferentiation assay to use as an initial screen for the genes identified using RNAseq. This involved the addition of neuregulin and serum to previously cyclic adenosine monophosphate differentiated SC. This assay was shown to recapitulate the changes seen in vivo, using RNAseq.