Fig. 2

α-Syn activates NLRP3 inflammasome via endocytosis and lysosomal impairment. a Immunoblot analysis of α-Syn in BV2 cells stimulated with A53T mutant or wide-type α-Syn, cytochalasin D (3 μM) inhibits endocytosis of α-Syn into BV2 cells. Data are presented as the mean ± S.E.M from four independent experiments. b Confocal microscopy of immortalized microglia BV2 cells incubated for 4 h with FITC-labeled α-Syn (10 μM) and then processed for immunocytochemistry, cell nuclei were visualized with hoechst. Data are presented as the mean ± S.E.M from three independent experiments. c Immunoblot analysis of caspase-1 in BV2 cells stimulated with A53T mutant or wide-type α-Syn, cytochalasin D (3 μM) inhibits activation of caspase-1 in a concentration-dependent manner in BV2 cells. Data are presented as the mean ± S.E.M from three independent experiments. d ELISA of the release of IL-1β into supernatants of BV2 cells treated with cytochalasin D during stimulation with A53T mutant or wide-type α-Syn or ATP. Data are presented as the mean ± S.E.M from four independent experiments. e α-Syn-containing lysosomes adopt a swollen morphology and underwent structural damage once α-Syn was phagocytosed by BV2 cells. Data are presented as the mean ± S.E.M from three independent experiments. f WT or A53T α-Syn in turn triggers the release of lysosomal protease cathepsin B into the cytoplasm. g-h Cathepsin B inhibitor significantly suppresses α-Syn evoked increase of caspase-1 expression and IL-1β production. Data are presented as the mean ± S.E.M from four independent experiments. * p < 0.05, ** p < 0.01 vs. control group, # p < 0.05, ## p < 0.01 vs. α-Syn treatment group