Fig. 1

Biogenesis, secretion, and internalization of exosomes. The formation of exosomes initially depends on the invagination of the plasma membrane, followed by the generation of ILVs and MVBs. Once mature, MVBs can fuse with lysosomes and be degraded, or integrate with the plasma membrane and finally get released, i.e., exosomes. During this process of synthesis and secretion, ESCRT-dependent and ESCRT-independent mechanisms are two common approaches, other components like the Rab family of GTPases, SNARE, ceramide, and tetraspanins are also involved. Exosomes can be uptake by receptor cells to perform specific functions through various mechanisms, such as phagocytosis, macro-pinocytosis, ligand-receptor interaction, CME, and CDE. As plasma membrane-derived vesicles with lipid bilayer structure, exosomes carry a variety of components, including RNAs (mRNA, MiRNA, LncRNA, and CircRNA), proteins (TSG101, Alix, HSP, CD9, CD63, and CD81) and metabolites, etc.