Figure 2.

Proposed mechanisms of aSyn secretion. aSyn can be secreted both in its monomeric or aggregated forms by non-classical exocytic or endocytic pathways. aSyn can be directly integrated into secretory vesicles and subsequently released by exocytosis (1). Alternatively, aSyn can be translocated to early endosomes. From early endosomes, aSyn protein can either be released to the extracellular space through the recycling endosome (2) or incorporated to intraluminal vesicles of multivesicular bodies (MBV). MVB cargo including aSyn can be directed to degradation by fusion with lysosomes or to secretion by fusion with the plasma membrane and release of exosomal vesicles (3). TGN=trans-Golgi network