Single cell multi-omics analysis reveals novel roles for DNA methylation in sensory neuron injury responses

DNA methylation is implicated in neuronal injury response and regeneration, but its role in regulating stable transcription changes in different types of dorsal root ganglion (DRG) neurons is unclear. In this study, we simultaneously profiled both the DNA methylome and mRNA transcriptome from single DRG neurons at different ages under either control or peripheral nerve injury condition. We found that age-related expression changes in Notch signaling genes and methylation changes at Notch receptor binding sites are associated with the age-dependent decline in peripheral nerve regeneration potential. Moreover, selective hypomethylation of AP-1 complex binding sites on regeneration-associated gene (RAG) promoters coincides with RAG transcriptional upregulation after injury. Consistent with the findings that different subtypes of DRG neurons exhibit distinct methylome changes upon injury responses, in a hybrid CAST/Ei; C57BL/6 genetic background, we further observed allele-specific gene regulation and methylation changes for many RAGs after injury. We suggest that the genetic background determines distinct allele-specific DNA methylomes, which contribute to age-dependent regulation and neuronal subtype-specific injury-responses in different mouse strains.