Translational Neurodegeneration Section "Albrecht Kossel," Department of Neurology, University Medical Center Rostock, University of Rostock, Rostock, Germany.
Center for Transdisciplinary Neurosciences Rostock, University Medical Center Rostock, University of Rostock, Rostock, Germany.
Mov Disord. 2023 Oct;38(10):1822-1836. doi: 10.1002/mds.29525. Epub 2023 Jul 14.
It is generally believed that the pathogenesis of PINK1/parkin-related Parkinson's disease (PD) is due to a disturbance in mitochondrial quality control. However, recent studies have found that PINK1 and Parkin play a significant role in mitochondrial calcium homeostasis and are involved in the regulation of mitochondria-endoplasmic reticulum contact sites (MERCSs).
The aim of our study was to perform an in-depth analysis of the role of MERCSs and impaired calcium homeostasis in PINK1/Parkin-linked PD.
In our study, we used induced pluripotent stem cell-derived dopaminergic neurons from patients with PD with loss-of-function mutations in PINK1 or PRKN. We employed a split-GFP-based contact site sensor in combination with the calcium-sensitive dye Rhod-2 AM and applied Airyscan live-cell super-resolution microscopy to determine how MERCSs are involved in the regulation of mitochondrial calcium homeostasis.
Our results showed that thapsigargin-induced calcium stress leads to an increase of the abundance of narrow MERCSs in wild-type neurons. Intriguingly, calcium levels at the MERCSs remained stable, whereas the increased net calcium influx resulted in elevated mitochondrial calcium levels. However, PINK1-PD or PRKN-PD neurons showed an increased abundance of MERCSs at baseline, accompanied by an inability to further increase MERCSs upon thapsigargin-induced calcium stress. Consequently, calcium distribution at MERCSs and within mitochondria was disrupted.
Our results demonstrated how the endoplasmic reticulum and mitochondria work together to cope with calcium stress in wild-type neurons. In addition, our results suggests that PRKN deficiency affects the dynamics and composition of MERCSs differently from PINK1 deficiency, resulting in differentially affected calcium homeostasis. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
普遍认为 PINK1/parkin 相关帕金森病（PD）的发病机制是由于线粒体质量控制紊乱。然而，最近的研究发现 PINK1 和 Parkin 在线粒体钙稳态中发挥重要作用，并参与调节线粒体-内质网接触位点（MERCSs）。
我们的研究旨在深入分析 MERCSs 和钙稳态受损在 PINK1/Parkin 相关 PD 中的作用。
在我们的研究中，我们使用了 PINK1 或 PRKN 丧失功能突变的 PD 患者诱导多能干细胞衍生的多巴胺能神经元。我们采用基于 GFP 分裂的接触位点传感器，结合钙敏感染料 Rhod-2 AM，并应用 Airyscan 活细胞超分辨率显微镜，确定 MERCSs 如何参与调节线粒体钙稳态。
我们的结果表明，毒胡萝卜素诱导的钙应激导致野生型神经元中窄型 MERCSs 的丰度增加。有趣的是，MERCSs 处的钙水平保持稳定，而增加的净钙内流导致线粒体钙水平升高。然而，PINK1-PD 或 PRKN-PD 神经元在基线时显示出 MERCSs 的丰度增加，并且在毒胡萝卜素诱导的钙应激下无法进一步增加 MERCSs。因此，MERCSs 和线粒体内部的钙分布被破坏。
我们的结果展示了内质网和线粒体如何在野生型神经元中协同应对钙应激。此外，我们的结果表明，PRKN 缺乏与 PINK1 缺乏不同，会影响 MERCSs 的动力学和组成，从而导致钙稳态受到不同的影响。© 2023 作者。运动障碍由 Wiley 期刊代表国际帕金森病和运动障碍学会出版。
