fig1

Figure 1. Secretory pathways in (neuro)endocrine cells. In endocrine cells and neurons, peptide hormones, neuropeptides, trophic factors, and granins are sorted at the TGN into immature vesicles that then mature to become DCV. Their content is released via the RSP upon stimulation. Other proteins in the Golgi complex are packaged into constitutive vesicles and secreted via the CSP, a default pathway. sEVs originate from ILVs formed through either endocytic pathway or possibly ER/Golgi secretory pathway. They are then taken up by MVBs. When the MVBs fuse with the plasma membrane, the sEVs are released. TGN: trans-Golgi network; DCV: dense core vesicles; RSP: regulated secretory pathway; CSP: constitutive secretory pathway; sEVs: small extracellular vesicles; ILVs: intraluminal vesicles; ER: endoplasmic reticulum; MVBs: multivesicular bodies.