Phosphatidylinositol 4,5-bisphosphate impacts extracellular vesicle shedding from <i>C. elegans</i> 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 crucial 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 in C. elegans by manipulating the 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 cargoes 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 cargoes in the cilium, but not the sorting of the protein cargoes 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.