Sex-dependent and Sex-independent Gene Regulation after Peripheral Nerve Injury

Peripheral nerve injury (PNI) induces cascades of gene expression changes in the central nervous system (CNS). However, there are still many uncertainties regarding the mechanisms of gene regulation that are sex-dependent and sex-independent. In this study, I examined the sex differences and similarities in the transcriptome and DNA methylome of rodents after PNI.In my first Aim, I characterized the transcriptional similarities and differences between sexes and species after PNI. Based on the differentially expressed genes in mice and rats of both sexes, I generated a post-PNI interactome. Using this conserved network, I developed a workflow for repurposing drugs through the interrogation of the Drug Gene interaction database. Fostamatinib, the top hit from this approach, was evaluated in vivo. I found that intrathecally administering the active metabolite of fostamatinib, R406, reverses pain hypersensitivity in both sexes. In my second Aim, I characterized sex differences in the spinal cord, periaqueductal gray (PAG), and blood of animals without nerve injury. I found that PNI changes the DNA methylation landscape in a sex-specific manner in all three tissues. I discovered that PNI resulted in genome-wide hypermethylation throughout the spinal cord and blood of both sexes. I identified robust sex differences in the global methylation of PAG. I found global hypermethylation in male PAG and global hypomethylation in female PAG after PNI. Moreover, I discovered genes that were differentially methylated in blood after PNI. A major discovery I made was that the methylation levels of the P2rx4 promoter differed by sex; After PNI, the P2rx4 regulatory region is more methylated in females than in males. Overall, findings from this thesis can be implicated in knowledge translation to find better tools and therapies. The workflow for repurposing drugs that I developed to predict the novel purpose of fostamatinib has the potential to accelerate drug development in other diseases. Moreover, identifying methylome changes in blood after PNI has the potential for developing novel stratification biomarkers.

Department dc:contributor.department

Physiology

Year dc:date.issued

2023

Author dc:creator

• Ghazisaeidi, Shahrzad

Advisor dc:contributor.advisor

• Salter, Michael W

• DNA Methylation
• Drug repurposing
• Neuropathic pain
• Peripheral Nerve Injury
• Sex
• Transcriptome

Handle dc:identifier.uri

http://hdl.handle.net/1807/138904

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/138904