School of Medical Science, Griffith University, Gold Coast, Queensland 4222, Australia.
School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
Mol Cell Neurosci. 2019 Dec;101:103416. doi: 10.1016/j.mcn.2019.103416. Epub 2019 Oct 22.
The accumulation of intracytoplasmic inclusion bodies (Lewy bodies) composed of aggregates of the alpha-synuclein (α-syn) protein is the principal pathological characteristic of Parkinson's disease (PD) and may lead to degeneration of dopaminergic neurons. To date there is no medication that can promote the efficient clearance of these pathological aggregates. In this study, the effect on α-syn aggregate clearance of ginkgolic acid (GA), a natural compound extracted from Ginkgo biloba leaves that inhibits SUMOylation amongst other pathways, was assessed in SH-SY5Y neuroblastoma cells and rat primary cortical neurons. Depolarization of SH-SY5Y neuroblastoma cells and rat primary cortical neurons with KCl was used to induce α-syn aggregate formation. Cells pre-treated with either GA or the related compound, anacardic acid, revealed a significant decrease in intracytoplasmic aggregates immunopositive for α-syn and SUMO-1. An increased frequency of autophagosomes was also detected with both compounds. GA post-treatment 24 h after depolarization also significantly diminished α-syn aggregate bearing cells, indicating the clearance of pre-formed aggregates. Autophagy inhibitors blocked GA-dependent clearance of α-syn aggregates, but not increased autophagosome frequency. Western analysis revealed that the reduction in α-syn aggregate frequency obtained with GA pre-treatment was accompanied by little change in the abundance of SUMO conjugates. The current findings show that GA can promote autophagy-dependent clearance of α-syn aggregates and may have potential in disease modifying therapy.
细胞内包涵体（路易体）的积累由α-突触核蛋白（α-syn）蛋白的聚集体组成，是帕金森病（PD）的主要病理特征，并可能导致多巴胺能神经元的退化。迄今为止，尚无药物可以促进这些病理聚集体的有效清除。在这项研究中，评估了从银杏叶中提取的天然化合物白果酸（GA）对 SH-SY5Y 神经母细胞瘤细胞和大鼠原代皮质神经元中α-syn 聚集体清除的影响，该化合物通过其他途径抑制 SUMOylation。用 KCl 去极化 SH-SY5Y 神经母细胞瘤细胞和大鼠原代皮质神经元可诱导α-syn 聚集体形成。用 GA 或相关化合物（漆酚）预处理的细胞，细胞内免疫阳性的α-syn 和 SUMO-1 聚集体明显减少。两种化合物都检测到自噬体的频率增加。去极化后 24 小时用 GA 进行后处理也显著减少了携带α-syn 聚集体的细胞，表明预先形成的聚集体被清除。自噬抑制剂阻断了 GA 依赖的α-syn 聚集体的清除，但不增加自噬体频率。Western blot 分析显示，GA 预处理减少α-syn 聚集体频率的同时，SUMO 缀合物的丰度几乎没有变化。目前的研究结果表明，GA 可以促进α-syn 聚集体的自噬依赖性清除，并且可能在疾病修饰治疗中有潜力。
