title: Regulation of exosome release by glycosphingolipids and flotillins.
abstract: 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.
authors.affiliation: Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital - The Norwegian Radium Hospital, Norway; Center for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Norway.
authors.forename: Santosh
authors.initials: S
authors.lastname: Phuyal
authors.forename: Nina P
authors.initials: NP
authors.lastname: Hessvik
authors.forename: Tore
authors.initials: T
authors.lastname: Skotland
authors.forename: Kirsten
authors.initials: K
authors.lastname: Sandvig
authors.forename: Alicia
authors.initials: A
authors.lastname: Llorente
mesh_terms: D002460:Cell Line; D002518:Ceramides / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D015536:Down-Regulation; D055354:Exosomes / Q000378:metabolism*; D006028:Glycosphingolipids / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*
chemical_list: D002518:Ceramides; D006028:Glycosphingolipids; D008565:Membrane Proteins; C106354:flotillins
keywords: exosome release; exosomes; extracellular vesicles; flotillins; lipids; rafts