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.
目的： 探讨组蛋白去乙酰化酶6（HDAC6）介导蛋白包涵体-自噬-溶酶体途径（AALP）在百草枯（PQ）诱导多巴胺能神经元自噬障碍中的作用。 方法： 以人神经母细胞瘤细胞（SH-SY5Y）作为多巴胺能神经元的体外模型，将细胞分为对照组和PQ染毒组（不同浓度PQ处理）。用不同浓度PQ （0、25、50、100、200和400 μmol/L）处理细胞24 h，100 μmol/L PQ处理细胞不同时间（0、12、24、36、48、60和72 h），CCK-8法检测细胞增殖活性；蛋白免疫印迹法（Western blot）检测细胞HDAC6、α-突触核蛋白（α-syn）、动力蛋白中链（Dynein IC1/2）、微管相关蛋白轻链3（LC3）、自噬相关蛋白（Beclin1）、泛素结合蛋白（p62）和溶酶体相关膜蛋白-1（Lamp-1）的表达水平；免疫荧光双标法观察细胞HDAC6、α-syn、Dynein IC1/2、LC3、Lamp-1及γ-微管蛋白（γ-tubulin）在细胞中的表达及定位。 结果： PQ呈剂量和时间依赖性抑制SH-SY5Y细胞增殖活性（R=-0.950、-0.960，P<0.05）；与对照组比较，PQ染毒组HDAC6、α-syn、p62蛋白表达水平升高，差异有统计学意义（P<0.05），而自噬标志蛋白（LC3 Ⅱ/LC3 Ⅰ）、Dynein IC1/2、Beclin1、Lamp-1表达水平降低（P<0.05）；与对照组比较，PQ染毒组HDAC6与α-syn荧光信号增强，蛋白表达水平增高，而Dynein IC1/2、LC3、Lamp-1荧光信号减少，蛋白表达水平降低（P<0.05）；PQ染毒诱导上述蛋白表达位置也发生变化，细胞质中的HDAC6由弥散状逐渐向细胞核聚集；α-syn、Dynein IC1/2、γ-tubulin、LC3、Lamp-1也逐渐由细胞质向细胞核聚集，并与HDAC6在细胞核共定位于核周区域。 结论： PQ可能通过诱导HDAC6介导蛋白包涵体-自噬-溶酶体途径障碍引起α-syn异常聚集。.
Keywords: Aggresome-autophagy-lysosome pathway; Autophagy; HDAC6; Paraquat.