| dc.description.abstract | Current research shows that altered microglia activity and persistent neuroinflammation are underlying factors to neurological diseases such as Alzheimer's, Parkinson's, multiple sclerosis and psychiatric illnesses. Additionally, these conditions show alterations in redox homeostasis and the accumulation of oxidative DNA lesions. DNA glycosylases, OGG1 and MUTYH, work to correct oxidative damage on the DNA through the base excision repair (BER) pathway and studies have shown that these glycosylases may have a role in epigenetically mediating gene expression. Indeed recent studies have shown that altered transcription mediated by OGG1 and MUTYH is related to cognition, memory and anxiety. Given this, it stands to reason that these DNA glycosylases may have a role in the regulation of the neuroinflammatory response in microglia cells. To understand the individual role of the OGG1 and MUTYH glycosylases in microglial activation and inflammatory signaling, OGG1 and MUTYH knockouts were generated from a human microglia cells line (CHME3). Cells were stimulated by \ch{H2O2} and analyzed for differences in inflammatory responses using RT-qPCR, LC-MS/MS and RNA-sequencing and potential epigenetic regulators were examined using LC-MS and ChIP.qPCR. Results showed no genotype-dependent differences in the expression of traditional inflammatory cytokines (IL-6, TNF$\upalpha$, IFN$\upgamma$, Nos2), the anti-inflammatory cytokine IL-4 or the microglia marker CD68. Pathway analysis of differential expression of protein and RNA, however, revealed genotype-dependent alterations in pathways important for microglial activation, immune responses and transcriptional regulation. Identified pathways include the WNT signaling pathways, involved in immune signaling and blood-brain-barrier integrity; \ch{K+} channels which mediate microglia activation; metabolic pathways involving insulin/glucagon and bile acids/salts, which have been linked to neuroinflammatory responses and neurodegenerative disease; and MECP2 regulation of transcription, including the regulation of neuronal channels. Further investigation to uncover the mechanisms behind the observed changes showed that these regulatory changes occur independently of 8-oxoG accumulation on genomic DNA and no changes in global 5-hydroxymethyl cytosine, indicating active demethylation, was found. Differentially expressed genes related to neuroinflammatory pathways (LRFN5, SNAI2, CNKSR2, AR and HAAO) were inspected closer to investigate if the activating H3K4me\textsuperscript{3} or repressive H3K27me\textsuperscript{3} histone methylation markers mediated by the polycomb repressive complex 2 (PRC2) were involved in the altered gene transcription, as has been seen before in relation to OGG1 and MUTYH. Results were not indicative of an involvement of PRC2 or either methylation mark in the regulation of the genes examined here. Overall, this study shows that OGG1 and MUTYH do have a role in the regulation of key neuroinflammatory processes in microglia cells, showing disruptions in key pathways related to neuroinflammatory disease, however, how this regulation is exacted remains to be shown. | en |