Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette.
Max Planck Institute for Molecular Genetics, Berlin, Germany.
Mov Disord. 2022 Jul;37(7):1405-1415. doi: 10.1002/mds.29025. Epub 2022 Apr 23.
Mutations in the E3 ubiquitin ligase parkin cause autosomal recessive Parkinson's disease (PD). Together with PTEN-induced kinase 1 (PINK1), parkin regulates the clearance of dysfunctional mitochondria. New mitochondria are generated through an interplay of nuclear- and mitochondrial-encoded proteins, and recent studies suggest that parkin influences this process at both levels. In addition, parkin was shown to prevent mitochondrial membrane permeability, impeding mitochondrial DNA (mtDNA) escape and subsequent neuroinflammation. However, parkin's regulatory roles independent of mitophagy are not well described in patient-derived neurons.
We sought to investigate parkin's role in preventing neuronal mtDNA dyshomeostasis, release, and glial activation at the endogenous level.
We generated induced pluripotent stem cell (iPSC)-derived midbrain neurons from PD patients with parkin (PRKN) mutations and healthy controls. Live-cell imaging, proteomic, mtDNA integrity, and gene expression analyses were employed to investigate mitochondrial biogenesis and genome maintenance. To assess neuroinflammation, we performed single-nuclei RNA sequencing in postmortem tissue and quantified interleukin expression in mtDNA/lipopolysaccharides (LPS)-treated iPSC-derived neuron-microglia co-cultures.
Neurons from patients with PRKN mutations revealed deficits in the mitochondrial biogenesis pathway, resulting in mtDNA dyshomeostasis. Moreover, the energy sensor sirtuin 1, which controls mitochondrial biogenesis and clearance, was downregulated in parkin-deficient cells. Linking mtDNA disintegration to neuroinflammation, in postmortem midbrain with PRKN mutations, we confirmed mtDNA dyshomeostasis and detected an upregulation of microglia overexpressing proinflammatory cytokines. Finally, parkin-deficient neuron-microglia co-cultures elicited an enhanced immune response when exposed to mtDNA/LPS.
Our findings suggest that parkin coregulates mitophagy, mitochondrial biogenesis, and mtDNA maintenance pathways, thereby protecting midbrain neurons from neuroinflammation and degeneration. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
E3 泛素连接酶 parkin 的突变导致常染色体隐性帕金森病 (PD)。Parkin 与 PTEN 诱导的激酶 1 (PINK1) 一起调节功能失调的线粒体清除。新的线粒体是通过核编码和线粒体编码蛋白的相互作用产生的，最近的研究表明 parkin 在这两个水平上影响这个过程。此外，parkin 被证明可以防止线粒体膜通透性，阻止线粒体 DNA (mtDNA) 逃逸和随后的神经炎症。然而，在源自患者的神经元中，parkin 独立于线粒体自噬的调节作用尚未得到很好的描述。
我们旨在研究 parkin 在防止神经元 mtDNA 动态平衡失调、释放和小胶质细胞激活中的作用。
我们从携带 parkin (PRKN) 突变的 PD 患者和健康对照中生成诱导多能干细胞 (iPSC) 衍生的中脑细胞。我们采用活细胞成像、蛋白质组学、mtDNA 完整性和基因表达分析来研究线粒体生物发生和基因组维持。为了评估神经炎症，我们对尸检组织进行了单细胞 RNA 测序，并在 mtDNA/脂多糖 (LPS) 处理的 iPSC 衍生神经元-小胶质细胞共培养物中定量白细胞介素的表达。
PRKN 突变患者的神经元显示线粒体生物发生途径缺陷，导致 mtDNA 动态平衡失调。此外，控制线粒体生物发生和清除的能量传感器 Sirtuin 1 在 parkin 缺陷细胞中下调。将 mtDNA 解体与神经炎症联系起来，在 PRKN 突变的尸检中脑，我们证实了 mtDNA 动态平衡失调，并检测到过度表达促炎细胞因子的小胶质细胞上调。最后，在暴露于 mtDNA/LPS 时，parkin 缺陷的神经元-小胶质细胞共培养物引发了增强的免疫反应。
我们的研究结果表明，parkin 共同调节线粒体自噬、线粒体生物发生和 mtDNA 维持途径，从而保护中脑细胞免受神经炎症和变性的影响。
