Altered Copper Neuronal Transport and Alzheimer's Disease

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Project Summary I hypothesize that apoplioprotein E (APOE)-associated dysregulation of hippocampal copper (Cu) metabolism is a key step in Alzheimer’s disease (AD) pathogenesis. This project will approach this topic from two specific aims: 1) establish the relationship between copper (I) cation distribution and AD pathology, and 2) study the APOE4-alteration effect on hippocampal synaptic pruning and Cu deposition in the mouse hippocampus. This approach is innovative in its use of two newly developed technologies that will be used to investigate hippocampal Cu dysregulation, synaptic density and its relation to the toxic APOE4 allele. The CRISP-17 fluorescent probe is a state-of-the-art tool in histochemical Cu localization, with a specificity for monovalent Cu far beyond other existing probes. CRISP-17 will visualize Cu distribution in post- mortem human AD hippocampal brain tissue. Synaptosome fractions will be isolated and measured for Cu using atomic emissions spectroscopy. Cu transport proteins will be downregulated in SH-SY5Y neuroblastoma cells, with effects on Cu deposition being analyzed using the fluorescent probe and synaptosome fractions being isolated and measured for Cu levels. Synaptic density will be studied in APOE4 knock-in mice and compared with the neuroprotective APOE3 knock-in mice with PET scans targeting the SV2A synaptic protein. Mouse brain tissue will then be taken and histochemically analyzed for monovalent Cu using CRISP-17, verifying this relationship in the animal model. We expect to find similarly that APOE4 knock-in mice have a greatly reduced synaptic density when compared to the neuroprotective APOE3 knock-in mice, with the mouse hippocampus also exhibiting a decrease in Cu distribution. These aims are designed to further the goals of the NIH by investigating a possible pathway to AD, a disease whose pathogenesis not yet fully defined.