Regulation of exosome release by glycosphingolipids and flotillins

• Published in: The FEBS journal 2014-05, Vol.281 (9), p.2214-2227
• Main Authors: Phuyal, Santosh, Hessvik, Nina P., Skotland, Tore, Sandvig, Kirsten, Llorente, Alicia
• Format: Article
• Language: English
• Subjects: Cell Line; Cellular biology; Ceramides - antagonists & inhibitors; Ceramides - biosynthesis; Down-Regulation; Enzymes; exosome release; exosomes; Exosomes - metabolism; extracellular vesicles; flotillins; Glycosphingolipids - antagonists & inhibitors; Glycosphingolipids - biosynthesis; Glycosphingolipids - metabolism; Humans; Lipids; Membrane Proteins - metabolism; Molecular biology; rafts
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.12775

Exosomes are released by cells after fusion of multivesicular bodies with the plasma membrane. The molecular mechanism of this process is still unclear. We investigated the role of sphingolipids and flotillins, which constitute a raft‐associated family of proteins, in the release of exosomes. Interestingly, our results show that dl‐threo‐1‐phenyl‐2‐decanoylamino‐3‐morpholino‐1‐propanol, an inhibitor of glucosylceramide synthase, seemed to affect the composition of exosomes released from PC‐3 cells. However, the inhibition of ceramide formation from the de novo pathway by fumonisin B1 did not affect exosome secretion. Moreover, in contrast to findings obtained with other cell lines published so far, inhibition of neutral sphingomyelinase 2, an enzyme that catalyzes the formation of ceramide from sphingomyelin, did not inhibit the secretion of exosomes in PC‐3 cells. Finally, small interfering RNA‐mediated downregulation of flotillin‐1 and flotillin‐2 did not significantly change the levels of released exosomes as such, but seemed to affect the composition of exosomes. In conclusion, our results reveal the involvement of glycosphingolipids and flotillins in the release of exosomes from PC‐3 cells, and indicate that the role of ceramide in exosome formation may be cell‐dependent. Exosomes are released by fusion of multivesicular bodies with the plasma membrane. Our results reveal that glycosphingolipids and flotillins affect the exosomes released from PC‐3 cells by changing their composition rather than the level of released exosomes. Furthermore, in PC‐3 cells there is no evidence for involvement of sphingomyelinase in the production of exosomes.