Oral Presentation Australia and New Zealand Society for Extracellular Vesicles Conference 2023

Altered protein nitrosylation patterns in extracellular vesicles from Alzheimer’s disease patients (#9)

Jereme G Spiers 1 2 3 , Natasha Vassileff 1 2 3 , Sarah E Bamford 4 , Rohan G.T Lowe 5 , Keshava K Datta 5 , Catriona McLean 6 , Paul Pigram 4 , Andrew Hill 1 7
  1. Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, Melbourne, VIC, Australia
  2. Clear Vision Research, Eccles Institute of Neuroscience, John Curtin School of Medical Research, College of Health and Medicine, The Australian National University, Acton, ACT, Australia
  3. The Australian National University, Acton, ACT, Australia
  4. Centre for Materials and Surface Science, Department of Mathematical and Physical Sciences, La Trobe University, Melbourne, VIC, Australia
  5. Proteomics Metabolomics Platform, La Trobe University, Melbourne, VIC, Australia
  6. The Florey Institute of Neuroscience & Mental Health, Melbourne, VIC, Australia
  7. Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia

Alzheimer’s disease (AD) is a progressive neurodegenerative condition known to alter the packaging and release of Extracellular Vesicles (EV) which may facilitate propagation of disease pathology. However, the factors contributing to this aberrant packaging are poorly understood. Neuroinflammation is an underlying feature of neurodegenerative conditions including AD. It is characterised by the production of numerous cytokines and free radicals including nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS). NO exerts its effect through post-translational S-nitrosylation of target cysteine thiols, altering the protein’s function in addition to its packaging into EVs. Despite this, the NO-modified proteome of EVs in AD has not been investigated. Therefore, this study aimed to determine the NO signalling changes occurring through post-translational modifications on EV protein cargo in AD. Brain derived EVs (BDEVs) isolated from the frontal cortex of human post-mortem AD brain tissue samples were thoroughly characterised, to meet the Minimal Information for Studies of Extracellular Vesicles guidelines, before undergoing iodolabelling and comparative proteomic analysis to identify NO-induced post-translational changes. The iodolabelling proteomic analysis revealed a protein profile indicative of neuroinflammation in the AD BDEVs. These included inflammatory, membrane surface, and mitochondrial proteins, suggesting their nitrosylation may play an important role in neuroinflammatory communication in AD. Together, this study is the first to show NO-induced S-nitrosylation post-translational changes in BDEVs demonstrating the effect NO signalling exerts on the protein cargo of EVs during AD.