Mitochondrial dysfunction and toxic protein aggregates have been shown to be key features in the pathogenesis of neurodegenerative diseases, such as Parkinson’s disease (PD). Functional analysis of genes linked to PD have revealed that the E3 ligase Parkin and the mitochondrial kinase PINK1 are important factors for mitochondrial quality control. PINK1 phosphorylates and activates Parkin, which in turn ubiquitinates mitochondrial proteins priming them and the mitochondrion itself for degradation. However, it is unclear whether dysregulated mitochondrial degradation or the toxic build-up of certain Parkin ubiquitin substrates is the driving pathophysiological mechanism leading to PD. The iron-sulphur cluster containing proteins CISD1 and CISD2 have been identified as major targets of Parkin in various proteomic studies. We employed in vivo Drosophila and human cell culture models to study the role of CISD proteins in cell and tissue viability as well as aged-related neurodegeneration, specifically analysing aspects of mitophagy and autophagy using orthogonal assays. We show that the Drosophila homolog Cisd accumulates in Pink1 and parkin mutant flies, as well as during ageing. We observed that build-up of Cisd is particularly toxic in neurons, resulting in mitochondrial defects and Ser65-phospho-Ubiquitin accumulation. Age-related increase of Cisd blocks mitophagy and impairs autophagy flux. Importantly, reduction of Cisd levels upregulates mitophagy in vitro and in vivo, and ameliorates pathological phenotypes in locomotion, lifespan and neurodegeneration in Pink1/parkin mutant flies. In addition, we show that pharmacological inhibition of CISD1/2 by rosiglitazone and NL-1 induces mitophagy in human cells and ameliorates the defective phenotypes of Pink1/parkin mutants. Altogether, our studies indicate that Cisd accumulation during ageing and in Pink1/parkin mutants is a key driver of pathology by blocking mitophagy, and genetically and pharmacologically inhibiting CISD proteins may offer a potential target for therapeutic intervention.

中文翻译：

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线粒体 CISD1/Cisd 积累阻止线粒体自噬，遗传或药理学抑制可挽救 Pink1/parkin 模型中的神经退行性表型

线粒体功能障碍和有毒蛋白质聚集体已被证明是帕金森病 (PD) 等神经退行性疾病发病机制的关键特征。对 PD 相关基因的功能分析表明，E3 连接酶 Parkin 和线粒体激酶 PINK1 是线粒体质量控制的重要因素。PINK1 磷酸化并激活 Parkin，进而泛素化线粒体蛋白，引发线粒体蛋白和线粒体本身降解。然而，目前尚不清楚线粒体降解失调或某些 Parkin 泛素底物的毒性积累是否是导致 PD 的驱动病理生理机制。在各种蛋白质组学研究中，含有蛋白质 CISD1 和 CISD2 的铁硫簇已被确定为 Parkin 的主要靶标。我们采用体内果蝇和人类细胞培养模型来研究 CISD 蛋白在细胞和组织活力以及与衰老相关的神经变性中的作用，特别是使用正交测定分析线粒体自噬和自噬的各个方面。我们发现果蝇同源物 Cisd 在 Pink1 和 Parkin 突变果蝇中以及衰老过程中积累。我们观察到 Cisd 的积累在神经元中特别具有毒性，导致线粒体缺陷和 Ser65-磷酸-泛素积累。Cisd 与年龄相关的增加会阻碍线粒体自噬并损害自噬通量。重要的是，Cisd 水平的降低可在体外和体内上调线粒体自噬，并改善 Pink1/parkin 突变果蝇的运动、寿命和神经变性的病理表型。此外，我们还发现，罗格列酮和 NL-1 对 CISD1/2 的药理学抑制可诱导人类细胞中的线粒体自噬，并改善 Pink1/parkin 突变体的缺陷表型。总而言之，我们的研究表明，衰老过程中以及 Pink1/parkin 突变体中 Cisd 的积累是通过阻断线粒体自噬而导致病理学的关键驱动因素，并且从遗传和药理学角度抑制 CISD 蛋白可能为治疗干预提供潜在的目标。