Department of Neurology Kyoto University Graduate School of Medicine, Kyoto, Japan.
Laboratory for Molecular Membrane Neuroscience, RIKEN Brain Science Institute, Saitama, Japan.
Hum Mol Genet. 2019 Jun 1;28(11):1894-1904. doi: 10.1093/hmg/ddz030.
Parkinson's disease (PD) is characterized by dopaminergic (DA) cell loss and the accumulation of pathological alpha synuclein (asyn), but its precise pathomechanism remains unclear, and no appropriate animal model has yet been established. Recent studies have shown that a heterozygous mutation of glucocerebrosidase (gba) is one of the most important genetic risk factors in PD. To create mouse model for PD, we crossed asyn Bacterial Artificial Chromosome transgenic mice with gba heterozygous knockout mice. These double-mutant (dm) mice express human asyn in a physiological manner through its native promoter and showed an increase in phosphorylated asyn in the regions vulnerable to PD, such as the olfactory bulb and dorsal motor nucleus of the vagus nerve. Only dm mice showed a significant reduction in DA cells in the substantia nigra pars compacta, suggesting these animals were suitable for a prodromal model of PD. Next, we investigated the in vivo mechanism by which GBA insufficiency accelerates PD pathology, focusing on lipid metabolism. Dm mice showed an increased level of glucosylsphingosine without any noticeable accumulation of glucosylceramide, a direct substrate of GBA. In addition, the overexpression of asyn resulted in decreased GBA activity in mice, while dm mice tended to show an even further decreased level of GBA activity. In conclusion, we created a novel prodromal mouse model to study the disease pathogenesis and develop novel therapeutics for PD and also revealed the mechanism by which heterozygous gba deficiency contributes to PD through abnormal lipid metabolism under conditions of an altered asyn expression in vivo.
帕金森病（PD）的特征是多巴胺能（DA）细胞丧失和病理性α-突触核蛋白（asyn）的积累，但确切的发病机制仍不清楚，也尚未建立合适的动物模型。最近的研究表明，葡萄糖脑苷脂酶（gba）的杂合突变是 PD 的最重要遗传风险因素之一。为了创建 PD 的小鼠模型，我们将 asyn 细菌人工染色体转基因小鼠与 gba 杂合敲除小鼠杂交。这些双突变（dm）小鼠通过其天然启动子以生理方式表达人源 asyn，并在易患 PD 的区域（如嗅球和迷走神经背核）中显示出 asyn 的磷酸化增加。只有 dm 小鼠表现出黑质致密部 DA 细胞的显著减少，表明这些动物适合作为 PD 的前驱模型。接下来，我们研究了 GBA 不足加速 PD 病理学的体内机制，重点关注脂质代谢。dm 小鼠表现出葡糖基神经酰胺苷水平升高，而没有明显的葡糖基神经酰胺积累，葡糖基神经酰胺是 GBA 的直接底物。此外，asyn 的过表达导致小鼠中 GBA 活性降低，而 dm 小鼠则倾向于表现出甚至更低的 GBA 活性。总之，我们创建了一种新型前驱小鼠模型，以研究疾病发病机制并为 PD 开发新的治疗方法，还揭示了杂合 gba 缺陷通过体内改变的 asyn 表达导致异常脂质代谢对 PD 的贡献的机制。
