A Dissertation submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in fulfilment of the requirements for the degree of Master of Science.
Johannesburg, 2015 / The free radical theory of aging postulates that accumulation of oxidative damage in major
cellular components is the predominant underlying cause of the aging phenotype. This damage
is caused most commonly by reactive oxygen species (ROS) and antioxidant enzymes such as the
superoxide dismutases (SOD) that neutralize ROS, are therefore vital. Manganese superoxide
dismutase (MnSOD) is particularly critical as it is functional in the mitochondria, a major site for
ROS generation. Numerous studies have demonstrated a tissue-specific decrease in the activity
and mRNA levels of major antioxidants, including MnSOD, with aging, however the exact
mechanism of this regulation is unclear. It was hypothesized that a general down-regulation of
various antioxidant enzymes such as this may occur at the transcriptional level. In order to
investigate SOD2 regulation, a comprehensively annotated rat SOD2 promoter region was
established using the appropriate bioinformatics tools. Following this, SOD2 mRNA levels in
tissues from young and old rat tissue were compared using quantitative PCR. The results showed
increased and decreased SOD2 mRNA levels in old compared to young liver tissue and brain
tissue, respectively, however these trends were not statistically significant. As MnSOD has been
shown to be epigenetically downregulated in various age-related diseases it was hypothesized
that the decrease in MnSOD mRNA levels seen in aging brain tissue may be a result of epigenetic
regulation at the SOD2 (MnSOD gene) promoter, specifically, through DNA methylation. A
methylation assay assessing the SOD2 gene promoter revealed no significant evidence of
hypermethylation. Although this suggests that promoter methylation is an unlikely mechanism
of SOD2 regulation in aging, further work would need to be implemented in order to prove this
conclusively.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/19358 |
| Date | 20 January 2016 |
| Creators | Bayley, Cassidy |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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