The mechanism of HDAC6 in paraquat-induced autophagy dysfunction of dopaminergic neurons by mediating aggresome-autophagy-lysosomal pathway

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Objective: To explore the mechanism of HDAC6 mediated aggresome-autophagy-lysosome pathway in paraquat-induced autophagy in dopaminergic neurons. Methods: Human neuroblastoma cell (SH-SY5Y cell) was used as model of dopaminergic neurons in vitro. The cells were treated with terminal concentrations of 0, 25, 50, 100, 200 and 400μmol/L PQ for 24 hours, and the cells were induced by 100 μmol/L PQ for different time (0, 12, 24, 36, 48, 60 and 72 h) . Cell viability was detected by CCK-8 assay. The expression levels of HDAC6, α-syn, Dynein IC1/2, LC3, Beclin1, p62 and Lamp-1 were detected by Western blot. Immunofluorescence double-labeling method was used to observe the expression and localization of HDAC6, α-syn, Dynein IC1/2, LC3, Lamp-1 and γ-tubulin in cells. Results: CCK-8 assay showed PQ induced cell survival rate decrease in a time and dose dependent manner (R=-0.950、-0.960, P<0.05) .Western blot showed that compared with control group, the protein levels of HDAC6, α-syn, p62 in PQ-exposed group were significantly increased (P<0.05) , but there was a significant decrease in expression level of the ratio of autophagy-related protein LC3 Ⅱ/LC3 Ⅰ, Beclin1, Dynein IC1/2, Lamp-1in PQ-exposed group (P<0.05) . The results of immunofluorescence double-labeling showed that compared with the control group, the fluorescence signals of HDAC6 and α-syn in the PQ-exposed group increased, and the protein expression level increased, while the fluorescence signals of Dynein IC1/2, LC3, and Lamp-1 decreased. The protein expression level is reduced. HDAC6 gradually accumulates from the diffuse shape to the nucleus; Under normal circumstances, α-syn, Dynein IC1/2, γ-tubulin, LC3, and Lamp-1 are mainly distributed in the cytoplasm. After PQ is infected, they gather in the nucleus and co-localize with HDAC6 in the area around the nucleus. Conclusion: PQ may induce abnormal aggregation of α-syn by inducing HDAC6-mediated aggresome-autophagy-lysosomal pathway disorder.