Fig. 1.

Biogenesis, release, uptake, and cellular functions of exosome and microvesicles in recipient cells. An early endosome matures and forms a multivesicular body (MVB) containing an intraluminal vesicle (ILV), which buds off into the lumen of the late endosome. The MVB then directly fuses with the plasma membrane (exosome release) or with the lysosome (degradation of intraluminal content). The endosomal sorting complex required for transport (endosomal sorting complex required for transport) or ceramide contributes to processes of MVB formation, protein cargo sorting, and lysosomal degradation or release of the exosome. Multiple mechanisms and factors, including intracellular calcium changes, intracellular lipids, the small Rab family GTPases, and the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) system, are involved in the transport and fusion of MVBs with the plasma membrane (exosome release). Microvesicles are produced by the direct outward budding of plasma membrane. After release, extracellular vesicles (EVs) interact with target cells via several ways, including interaction of an EV ligand with a protein (receptor) on the target cell membrane, endocytosis, phagocytosis, or direct delivery of EV cargo into the cytosol by membrane fusion. The molecular cargos of EVs regulate diverse cellular functions of target cells through intracellular signaling, gene regulation, and metabolism. miRNA, microRNA.