Investigating Redox Genes as Therapeutic Targets in Alzheimer's disease

Alzheimer's Disease (AD) likely manifests through a combination of genetic inheritance and environmental factors. Currently, the biggest risk factor for developing AD is age. Neurons are terminally differentiated and must be maintained throughout our entire lifetimes. However, during ageing levels of oxidative stress, in the form of reactive oxygen species (ROS) accumulate, which leads to oxidation of proteins/lipids, induces DNA damage and may eventually trigger neurodegeneration. Antioxidant mechanisms which usually protect neurons are decreased with age, and decreased to an even greater extent in the AD patient brain. Therefore, ways to enhance antioxidant capacity or prevent its decline in age may lead to promising outcomes. The GSH redox pathway represents the major antioxidant system present in cells and is directly influenced by the levels of ROS. Importantly, GSH cannot be synthesized within mitochondria and its import from thecytosol is critical. There is also growing evidence for an interplay between GSH redox imbalance and amyloid beta (AB). Despite this, dysregulation of the GSH redox pathway is largely understudied in the context of age-dependent neurodegeneration. The focus of this PhD studentship is to determine how redox changes in an AD model and test potential novel therapeutic targets. Aim 1) Deciphering the molecular mechanism of glutathione redox change in AD. We will investigate 20 enzymes in the redox pathway that may be contributing to neurodegenerative phenotypes in an AB Drosophila model of AD. Transgenic RNAi expressing lines will be driven specifically in neurons and genetically encoded fluorescent genetic reporter technology used to measure ROS and GSH. Importantly all genes in the GSH Redox pathway are highly conserved between Drosophila and humans and thus would give mechanistic insight into how Redox balance can be altered in vivo. Aim 2) Rescue AD associated phenotypes by enhancing glutathione-stransferase (GST) activity in vivo. Preliminary data, collected for this proposal shows that enhancing human Glutathione-S-Transferase (GST) expression can prolong lifespan in the AB Drosophila. To complement this finding the PhD student will analyze, basic behaviour, memory (through co-supervision with JH), protein aggregation in the brain, electrophysiological changes and neurodegeneration phenotypes to investigate how this protective mechanism occurs. Aim 3) Rescue AD associated phenotypes in a neuronal in vitro model by enhancing GST activity. The candidate will also investigate whether increased GSH in human neurons in vitro, via viral mediated transfection of GSTO1 and GSTS1, could rescue ROS accumulation (recorded by live cell imaging) and neurodegeneration, as seen following AB 40/42 fibril administration.