USP30 Inhibition as a Therapeutic Strategy in Parkinson's Disease

大量的证据表明，线粒体内稳态功能障碍是一个关键的病理生理 帕金森病（PD）的发病机制。维持一个健康的线粒体库需要一个 选择性降解功能障碍的线粒体的系统（"线粒体自噬"）。常染色体隐性遗传（AR）PD所致 帕金缺乏症与线粒体自噬缺陷直接相关线粒体功能障碍导致帕金 转移到线粒体外膜，在那里它与PINK1相互作用（另一个基因， 引起AR PD）使线粒体蛋白泛素化，从而诱导线粒体与 自噬体，然后是自噬降解。因此，帕金的损失导致了 线粒体自噬受损导致的线粒体功能障碍。.在这种情况下，我们假设， 线粒体自噬将保护免受α-突触核蛋白（α Syn）毒性。 可能通过直接结合线粒体膜上的TOM 20，从而干扰 线粒体蛋白输入。相反，功能失调的线粒体产生更多的活性氧， 物种（ROS），与PD脑中氧化损伤标志物的增加一致。此外，ROS可以 增加α Syn积累。然而，线粒体自噬在清除线粒体功能障碍中的作用， α Syn诱导的线粒体损伤的背景尚不清楚。USP30是一种去泛素化酶（DUB） 系在线粒体外膜上，在那里它直接去除了被 帕金，从而抵消帕金的能力，促进线粒体自噬。通过siRNA拯救USP30的敲低 线粒体自噬在帕金森病缺陷细胞和保护多巴胺能（DA）神经元在帕金森病缺陷果蝇。和 我们的初步数据表明，USP30基因敲除小鼠表现出增强的线粒体自噬和对 α Syn毒性。因此，抑制USP30是恢复线粒体自噬以实现细胞增殖的有吸引力的治疗策略。 PD中的神经保护。这些数据强调了PD中神经保护的主要潜力， 通过靶向USP 30调节线粒体自噬。考虑到这一目标，我们现在建议测试一个高度 特异性CNS渗透小分子抑制剂USP30对慢性退行性α Syn- 的PD小鼠模型，并评估α Syn清除和神经保护与 USP 30抑制对介导α Syn降解的特定途径的影响。这些结果可以提供 支持MTX 012或其他脑渗透药理学USP 30抑制剂向前发展， PD的临床神经保护研究

A large body of evidence implicates dysfunction of mitochondrial homeostasis as a key pathophysiological mechanism in Parkinson’s disease (PD). Maintenance of a pool of healthy functioning mitochondria requires a system for selectively degrading dysfunctional mitochondria (“mitophagy”). Autosomal recessive (AR) PD due to Parkin deficiency links directly to a defect in mitophagy. Mitochondrial dysfunction causes Parkin to translocate to the outer mitochondrial membrane where it interacts with PINK1 (another gene where mutations cause AR PD) to ubiquitinate mitochondrial proteins, thereby inducing fusion of mitochondria with autophagosomes, followed by autophagic degradation. Thus, loss of Parkin leads to the accumulation of dysfunctional mitochondria due to impaired mitophagy. . In this context, we hypothesize that enhancing mitophagy will protect against α-synuclein (αSyn) toxicity ΑSyn induces mitochondrial complex I dysfunction, potentially by directly binding to TOM20 on the mitochondrial membrane and thereby interfering with mitochondrial protein import. Conversely, dysfunctional mitochondria produce increased reactive oxygen species (ROS), consistent with increased markers of oxidative damage in the PD brain. Furthermore, ROS can increase αSyn accumulation. However, the role of mitophagy in clearing away dysfunctional mitochondria in the setting of αSyn induced mitochondrial impairment is unknown. USP30 is a deubiquitinating enzyme (DUB) tethered to the outer mitochondrial membrane, where it directly removes ubiquitin that had been attached by Parkin, thereby counteracting Parkin’s ability to promote mitophagy. Knock-down of USP30 by siRNA rescues mitophagy in Parkin-deficient cells and protects dopaminergic (DA) neurons in Parkin-deficient Drosophila. And our preliminary data suggest that USP30 knock-out mice show enchanced mitophagy and protection against αSyn toxicity. Thus, inhibition of USP30 is an attractive therapeutic strategy for restoring mitophagy to achieve neuroprotection in PD. These data highlight the major potential for neuroprotection in PD by specifically modulating mitophagy through targeting of USP30. With this goal in mind, we now propose to test a highly specific CNS-penetrant small molecular inhibitor of USP30 for neuroprotection in a slowly degenerative αSyn- based mouse model of PD, and to assess the degree to which αSyn clearance and neuroprotection relates to the impact of USP30 inhibition on specific pathways mediating αSyn degradation. These results could provide support for moving forward with MTX012 or other brain-penetrant pharmacological USP30 inhibitors towards clinical neuroprotection studies in PD.