Fig. 3.

Exosome biogenesis. Exosomes contain different genetic materials, lipids, and cytoplasmic proteins like miRNA, Non-coding RNA, DNA, enzymes, etc. The cargo is transported horizontally among cells. Microvesicular bodies (MVBs) containing intraluminal vesicles (ILVs) are fused with the plasma and release ILVs as exosomes out of cells. Early endosomes originating from external endocytic vesicles or Trans-Golgi network are fused with lysosomes or convert to MVBs. The endosomal sorting complexes required for transport (ESCRT) are composed of ESCRT-0, -1, -2, and 3 subsets, as well as specific AAA ATPase Vsp4 complex, supports budding into the luminal surface. Different Rab proteins are involved in the transportation of endocytic vesicles and early endosomes to integrate with lysosomes or mature to MVBs. Plus, Rabs, Ras, GTPase, together with sensitive factor attachment protein receptors (SNAREs) facilitate the MVBs fusion to the plasma membrane