Department of Biological Sciences, Columbia University, New York, NY, USA.
Departments of Psychiatry, Neurology, and Pharmacology, Columbia University: Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
Sci Rep. 2019 Aug 12;9(1):11682. doi: 10.1038/s41598-019-47952-5.
Mutations in the E3 ubiquitin ligase parkin are the most common known cause of autosomal recessive Parkinson's disease (PD), and parkin depletion may play a role in sporadic PD. Here, we sought to elucidate the mechanisms by which stress decreases parkin protein levels using cultured neuronal cells and the PD-relevant stressor, L-DOPA. We find that L-DOPA causes parkin loss through both oxidative stress-independent and oxidative stress-dependent pathways. Characterization of the latter reveals that it requires both the kinase PINK1 and parkin's interaction with phosphorylated ubiquitin (phospho-Ub) and is mediated by proteasomal degradation. Surprisingly, autoubiquitination and mitophagy do not appear to be required for such loss. In response to stress induced by hydrogen peroxide or CCCP, parkin degradation also requires its association with phospho-Ub, indicating that this mechanism is broadly generalizable. As oxidative stress, metabolic dysfunction and phospho-Ub levels are all elevated in PD, we suggest that these changes may contribute to a loss of parkin expression.
E3 泛素连接酶 parkin 的突变是最常见的常染色体隐性帕金森病 (PD) 的已知原因，而 parkin 的缺失可能在散发性 PD 中发挥作用。在这里，我们试图利用培养的神经元细胞和与 PD 相关的应激源 L-DOPA 来阐明应激降低 parkin 蛋白水平的机制。我们发现，L-DOPA 通过氧化应激独立和依赖的途径导致 parkin 的丢失。对后者的特征分析表明，它需要激酶 PINK1 和 parkin 与磷酸化泛素（磷酸化 Ub）的相互作用，并通过蛋白酶体降解介导。令人惊讶的是，自泛素化和线粒体自噬似乎不是这种丢失所必需的。在过氧化氢或 CCCP 诱导的应激反应中，parkin 的降解也需要其与磷酸化 Ub 的结合，这表明这种机制具有广泛的通用性。由于氧化应激、代谢功能障碍和磷酸化 Ub 水平在 PD 中均升高，我们认为这些变化可能导致 parkin 表达的丧失。
