Complex N-Linked Glycans Serve as a Determinant for Exosome/Microvesicle Cargo Recruitment

Exosomes, also known as microvesicles (EMVs), are nano-sized membranous particles secreted from nearly all mammalian cell types. These nanoparticles play critical roles in many physiological processes including cell-cell signaling, immune activation, and suppression and are associated with disease states such as tumor progression. The biological functions of EMVs are highly dependent on their protein composition, which can dictate pathogenicity. Although some mechanisms have been proposed for the regulation of EMV protein trafficking, little attention has been paid to N-linked glycosylation as a potential sorting signal. Previous work from our laboratory found a conserved glycan signature for EMVs, which differed from that of the parent cell membranes, suggesting a potential role for glycosylation in EMV biogenesis. In this study, we further explore the role of glycosylation in EMV protein trafficking. We identify EMV glycoproteins and demonstrate alteration of their recruitment as a function of their glycosylation status upon pharmacological manipulation. Furthermore, we show that genetic manipulation of the glycosylation levels of a specific EMV glycoprotein, EWI-2, directly impacts its recruitment as a function of N-linked glycan sites. Taken together, our data provide strong evidence that N-linked glycosylation directs glycoprotein sorting into EMVs.