Prova, N. S. | bioRxiv Science

bioRxiv2025

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.

cell biology↗

bioRxiv2025

Phosphatidylinositol (4,5)-bisphosphate Impacts Ectosome Shedding from C. elegans Ciliated Sensory Neurons

Small secreted extracellular vesicles (EVs) mediate intercellular transport of bioactive macromolecules. How the membrane lipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), which plays a critical role in many cellular processes, impacts EV biogenesis is unclear. The primary cilium, a sensory organelle protruding from most non-dividing cells, transmits signals by shedding EVs called ectosomes. Here, we altered ciliary PI(4,5)P2 by manipulating expression of the type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K1) PPK-1 and deletion of the phosphoinositide 5-phosphatase (INPP5E) inpp-1, then determined the impact on release of EVs that carried cargos tagged with fluorescent proteins. We discovered that increasing PI(4,5)P2 differentially affected ectosome shedding from distinct compartments, decreasing biogenesis of an EV subpopulation from the ciliary base, but enhancing budding from the cilium distal tip. Altering PI(4,5)P2 levels also impacted the abundance and distribution of EV cargos in the cilium, but not the sorting of the protein cargos into distinct subsets of ectosomes. Finally, manipulating PI(4,5)P2 did not affect cilium length, suggesting that changing PI(4,5)P2 levels can serve as a mechanism to regulate ectosome biogenesis in response to physiological stimuli without impacting cilium morphology. Summary StatementExtracellular vesicles (EVs), released from most, if not all, cell types, share bioactive cargo that cannot readily cross the plasma membrane with recipient cells. EVs play numerous roles in physiological processes as well as the propagation of pathophysiological conditions, including cancer, neurodegenerative, kidney, and cardiovascular diseases. Here, we sought to determine the impact of the membrane lipid phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2) on EV biogenesis. We used a genetic approach to manipulate PI(4,5)P2 levels in the primary cilium, a specialized sensory organelle that serves as a platform for signal transmission by shedding EVs. We discovered that high PI(4,5)P2 differentially impacts two distinct EV subpopulations, decreasing shedding of ectosomes derived from the ciliary base, but increasing budding from the cilium distal tip. This work defines a new role for PI(4,5)P2 in the regulation of EV biogenesis and ciliary biology.

cell biology↗