The profiling of extracellular vesicle subtypes in Huntington’s disease brains identifies Alix as a novel marker of neuropathology

ABSTRACT: Background: Huntington’s disease (HD) is an inherited autosomal dominant disorder characterized by progressive degeneration of the striatum and cerebral cortex, caused by a mutation in the huntingtin gene, which includes an aberrant expansion of a CAG repeat. The mutant huntingtin protein accumulates in endosomal compartments and alters the endosomal-lysosomal system, which can affect the production, secretion, and content of exosomes - extracellular vesicles (EVs) with an endosomal origin. Therefore, we investigated whether the levels and content of small EV subpopulations, including exosomes, are altered in the brains of HD patients. Methods: We isolated and characterized the proteome of two subtypes of small EVs from the striatum and cortex of HD brains with early or advanced degeneration, as well as from control brains, using differential ultracentrifugation followed by a high-resolution iodixanol density gradient and mass spectrometry analysis. Additionally, we explored the secretion of EVs by fibroblasts from HD patients compared to controls. Results: Our data indicate that the level of Annexin A2-enriched EVs increased in the HD cortex, whereas the level of Alix-enriched EVs was reduced in both the HD striatum and cortex compared to controls. In terms of content per EV, we found that the level of Annexin A2 and Alix were increased and reduced in HD, respectively. This altered cargo of Alix in EVs paralleled a progressive decrease in Alix protein in the cortex and striatum of HD patients, which correlated with the neuropathological state of the brain. Furthermore, in vitro, HD fibroblasts secreted EVs that were less enriched in Alix as compared to control fibroblasts, despite showing similar Alix protein levels in the cell lysates. Conclusions: Taken together, our data provide new insights into the pathophysiology of brain EVs in HD, identifying Alix as a novel marker of neuropathology. This opens new avenues to explore Alix as a potential biomarker of disease progression in peripheral tissues.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Brain, Extracellular Vesicle

DISEASE(S): Huntington Disease

SUBMITTER: Eva Borràs  

LAB HEAD: Eduard Sabido

PROVIDER: PXD060574 | Pride | 2025-12-10

REPOSITORIES: Pride