Fig. 3
From: Exosome biogenesis: machinery, regulation, and therapeutic implications in cancer
Mechanisms mediating the transport and fate of MVBs. After the maturation of MVBs, they can either fuse with lysosome or fuse with plasma membrane. The activity of Rab7 plays a pivotal role for the fate of MVBs. Mon1a/b and neddylated Coro1a can activate Rab7 and promote dynein-dependent retrograde transport of MVBs towards the minus-end or perinuclear region. On the other hand, Arl8b/SKIP/HOPS/ TBC1D15 cascade or Rab31/TBC1D2B cascade could inactivate RAB7 and promote kinesin dependent antegrade transport of MVBs towards the plus-end or cell periphery. The antegrade transport of MVBs and their docking, tethering and fusion with plasma membrane are controlled by multiple factors including both proteins and lncRNAs. Notably, after the formation of MVBs, the ILVs inside can still retrofuse with the limiting membrane of MVBs and these ILVs are referred as retrofusing ILVs (rILVs). The others are recognized as secretory ILVs (sILVs) or degradative ILVs (dILVs)