C-Jun DNA Binding During Axon Regeneration

Axons in the Peripheral Nervous System are able to regenerate after injury, unlike axons in the Central Nervous System. We examined the Dorsal Root Ganglion (DRG) model of Peripheral Nervous System axon regeneration. First, we surveyed the transcriptomic response of DRG neurons to peripheral axotomy as measured by several different RNAseq experiments and examined which transcriptional regulators drive that response. We found that independent RNAseq experiments can yield highly replicative results at both the levels of differentially expressed genes as well as transcription factor regulators when the data sets are properly normalized. Next, we used chromatin immunoprecipitation followed by high-throughput sequencing to measure the genomic locations bound by one transcriptional regulator, c-Jun, in DRG neurons after a peripheral axotomy or a sham surgery in order to better understand c-Jun’s transcriptional activities during axon regeneration. We found that c-Jun carries out the majority of its axonal injury-responsive transcriptional regulation at enhancer sites rather than at promoter regions. Finally, the effects of eight Jun-containing dimers on neurite outgrowth were tested in cortical and hippocampal neurons in culture. We demonstrated that dimers composed of Jun and Atf3 are sufficient to promote neurite outgrowth of cortical and hippocampal neurons in culture. In summary, this work clarifies the mechanism of axon regeneration of DRG neurons at the levels of their transcriptomic response to injury and transcriptional regulation by c-Jun