Superoxide dismutase impacts extracellular vesicle biogenesis and uptake

Extracellular vesicles (EVs), which transfer bioactive macromolecules between cells, play an important role in the pathogenesis of multiple neurodegenerative diseases. Focus has centered on how altered EV contents propagate disease and the potential for EVs as diagnostic biomarkers, while the effect of pathogenic factors on EV release is less understood. Here, we defined how the key antioxidant enzyme superoxide dismutase 1 (SOD-1) affects EV shedding from sensory neuron primary cilia, enrichment of ciliary proteins packaged into EVs, and uptake of EVs by surrounding glia in vivo by imaging C. elegans expressing fluorescent protein-tagged EV cargos. We discovered that loss of SOD-1, as well as the SOD-1(G85R) amyotrophic lateral sclerosis (ALS) pathogenic variant, increased EV shedding from the cilium distal tip, and this was associated with greater abundance of EV cargo in this ciliary compartment. In contrast, loss of SOD-1 reduced the glial uptake of a different cargo present in EVs shed from the ciliary base. Together, this suggests that redox balance has a subtype-specific effect on EV biogenesis, influencing neuron communication in vivo.