Parkinson's Disease (PD) is characterized by dopaminergic neurodegeneration in the substantia nigra. The exact mechanism by which dopaminergic neurodegeneration occurs is still unknown; however, mitochondrial dysfunction has long been implicated in PD pathogenesis. To investigate the sub-cellular events that lead to disease progression and to develop personalized interventions, non-neuronal cells which are collected in a minimally invasive manner can be key to test interventions aimed at improving mitochondrial function. We used human skin fibroblasts from sporadic PD (sPD) patients as a cell proxy to detect metabolic and mitochondrial alterations which would also exist in a non-neuronal cell type. In this model, we used a glucose-free/galactose- glutamine- and pyruvate-containing cell culture medium, which forces cells to be more dependent on oxidative phosphorylation (OXPHOS) for energy production, in order to reveal hidden metabolic and mitochondrial alterations present in fibroblasts from sPD patients. We demonstrated that fibroblasts from sPD patients show hyperpolarized and elongated mitochondrial networks and higher mitochondrial ROS concentration, as well as decreased ATP levels and glycolysis-related ECAR. Our results also showed that abnormalities of fibroblasts from sPD patients became more evident when stimulating OXPHOS. Under these culture conditions, fibroblasts from sPD cells presented decreased basal respiration, ATP-linked OCR and maximal respiration, and increased mitochondria-targeting phosphorylation of DRP1 when compared to control cells. Our work validates the relevance of using fibroblasts from sPD patients to study cellular and molecular changes that are characteristic of dopaminergic neurodegeneration of PD, and shows that forcing mitochondrial OXPHOS uncovers metabolic defects that were otherwise hidden.

中文翻译：

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散发性男性帕金森氏病患者的人皮肤成纤维细胞中的线粒体重塑揭示了代谢和线粒体生物能缺陷。

帕金森氏病（PD）的特征是黑质中的多巴胺能神经变性。多巴胺能神经变性发生的确切机制仍是未知的。然而，线粒体功能障碍长期以来一直与PD的发病机理有关。为了研究导致疾病进展的亚细胞事件并发展个性化干预措施，以微创方式收集的非神经元细胞可能是测试旨在改善线粒体功能的干预措施的关键。我们使用来自散发性PD（sPD）患者的人类皮肤成纤维细胞作为细胞代理来检测在非神经元细胞类型中也存在的代谢和线粒体改变。在此模型中，我们使用了不含葡萄糖/半乳糖，谷氨酰胺和丙酮酸的细胞培养基，它迫使细胞更依赖于氧化磷酸化（OXPHOS）产生能量，以揭示sPD患者成纤维细胞中隐藏的代谢和线粒体变化。我们证明，来自sPD患者的成纤维细胞显示超极化和延长的线粒体网络和更高的线粒体ROS浓度，以及降低的ATP水平和与糖酵解相关的ECAR。我们的结果还表明，当刺激OXPHOS时，来自sPD患者的成纤维细胞异常变得更加明显。在这些培养条件下，与对照细胞相比，来自sPD细胞的成纤维细胞呈现出基础呼吸减少，ATP连接的OCR和最大呼吸，以及DRP1的线粒体靶向磷酸化增加。