Introduction: Huntington’s disease (HD) is a genetic neurological disorder that is characterised by decline in movement, cognition, and behaviour. It is imperative to understand the progression of HD due to the absence of treatment and therapeutic targets. In the past decade, research has demonstrated that extracellular vesicles (EVs) play a role in the pathogenesis of neurodegenerative diseases and that the protein content of EVs can provide insights into underlying disease mechanisms. To elucidate the potential role of EVs in HD, we investigated the protein cargo of EVs isolated from human tissue and a mouse model of HD.
Methods: EVs were isolated from the extracellular matrix of human HD and neurological control parietal brain tissue (n=8) or the cortex, striatum, and hippocampus of the R6/1 transgenic mouse model of HD and wild-type controls (n=10) by differential centrifugation, size exclusion chromatography and ultrafiltration. EVs were characterised by immunoblot, transmission electron microscopy and liquid chromatography mass spectrometry-based proteomics.
Results: Our studies highlighted the enrichment of EV markers in immunoblotting and proteomics demonstrating successful isolation of EVs. Proteomics identified 182 unique proteins in human HD parietal tissue and 171 unique proteins in HD EVs, with presence of proteins associated with the mitochondrial, lysosomal, endosomal and autophagy pathways. Analysis of the protein cargo of murine brain-derived EVs is on-going.
Conclusion: This is the first study to comprehensively characterise the cargo of EVs in HD human and mouse brain. This research provides an important step towards the identification of novel disease mechanisms and possible therapeutics targets.