Blanthorn-Hazell, Sophee and Parkin, Edward (2015) The role of the E2 copper binding domain in the cell biology of the amyloid precursor protein. Masters thesis, Lancaster University.
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Abstract
Alzheimer’s disease is a neurodegenerative disorder characterised by the accumulation, in the brain, of neurotoxic amyloid beta-(Aβ) peptides. These peptides are generated from the amyloid precursor protein (APP) via the amyloidogenic proteolytic pathway which also leads to the formation of soluble APP beta (sAPPβ). Alternatively, APP can be cleaved by the non-amyloidogenic pathway in which an α-secretase activity cleaves the protein within the Aβ region generating soluble APP alpha (sAPPα). APP itself binds to copper at a number of sites, including a recently identified E2 copper binding domain (E2 CuBD) within the extracellular region of the protein. The current project aims were to investigate how copper binding within the APP E2 CuBD might influence the expression, proteolysis, cellular localisation and cytotoxicity of APP. In order to achieve this, a range of E2 CuBD mutants were generated in which various metal-co-ordinating histidine residues were mutated to alanine. These constructs were expressed in HEK and SH-SY5Y cells and the effects of the mutations on the afore mentioned properties of APP were assessed. The results show that these mutations had little consistent effect on the expression, proteolysis or cellular localisation of APP. Furthermore, whilst wild-type APP accentuated copper-mediated cytotoxicity in HEK and SH-SY5Y cells, mutating the histidine residues in the E2 domain of the protein had little effect on this phenomenon. Thus, it would appear that copper binding to the E2 domain of APP is, most likely, not an important event in the pathogenesis of Alzheimer's disease.