Investigating peroxisome dysregulation in Alzheimer’s disease
Application deadline: 23 November 2018
Start date: October 2019
Research theme: INeuroscience and Mental Health
Peroxisomes are critical organelles for both the processing of fatty acids required for metabolism and for the quenching of reactive oxygen species that build up during cell stress. Several interesting peroxisomal observations have been made in the AD patient brain at post-mortem. Firstly, AD brains have higher levels of C22:0 and specific very long-chain fatty acids that are substrates for peroxisomal β-oxidation, suggesting peroxisomal function is compromised. Secondly, peroxisomes were found to be absent in neuronal processes containing abnormally phosphorylated tau and loss of peroxisomes is inversely correlated to Beta-amyloid (AB) deposition. Despite these observations there is currently no cell biological mechanism for how peroxisomal changes manifest in AD. It is also unclear if and how peroxisomal dysregulation contributes to disease progression.
Project aims and method
This project aims to address these outstanding questions using a multidisciplinary and collaborative approach.
- Aim 1 (Year 1): To determine the peroxisome response using in vivo models of AD. In this project you will first determine how peroxisomes respond to the specific pathogenic proteins associated with AD in vivo. We will express human mutant tau or aggregation prone amyloid beta (AB), in Drosophila, restricting expression only to adult neurons. Genetically encoded fluorescent markers will be used to label peroxisomes and neurons in vivo. Peroxisomal number, distribution, size and trafficking in neuronal projections will then be analysed by live cell imaging, using a specialized chamber and confocal microscopy. Peroxisomal phenotypes will also be investigated in Drosophila lines lacking newly discovered AD risk genes, derived from GWAS studies at Cardiff University.
- Aim 2 (Year 2): To investigate the mechanisms of peroxisomal changes in vivo. You will learn Drosophila epistasis experiments to determine the genetic pathway in which these peroxisomal phenotypes manifest. Several commercially available RNAi fly lines, targeting specific peroxisomal molecules involved in B-oxidation, fission molecules or transport will be crossed to Drosophila models of AD. The following hallmark phenotypes will be assessed: lifespan, electrophysiology, locomotor dysfunction, pathology and neuronal loss. Any peroxisomal genes that can alter disease progression are potential drug targets and warrant further investigation.
- Aim 3 (Year 3): To investigate peroxisomal changes in mammalian neurons in vitro. Peroxisomal changes will also be investigated using cutting edge CRISPR/Cas9 technology to ablate 1-3 select peroxisomal regulating genes in a human neuroblastoma cell line. You will then analyse lipid profiles and peroxisome motility using state-of-the-art imaging techniques and determine peroxisomal pH using a novel dye, to determine precisely how each gene contributes to peroxisomal dysfunction.
Prof Michael Schrader, University of Exeter.