Redmann Matthew, Wani Willayat Y, Volpicelli-Daley Laura, Darley-Usmar Victor, Zhang Jianhua
Department of Pathology, University of Alabama at Birmingham, USA; Center for Free Radical Biology, University of Alabama at Birmingham, USA.
Center for Neurodegeneration, Experimental Therapeutics, University of Alabama at Birmingham, USA; Department of Neurology, University of Alabama at Birmingham, USA.
Redox Biol. 2017 Apr;11:429-437. doi: 10.1016/j.redox.2016.12.032. Epub 2017 Jan 3.
Parkinson's disease is a debilitating neurodegenerative disorder that is pathologically characterized by intracellular inclusions comprised primarily of alpha-synuclein (αSyn) that can also be transmitted from neuron to neuron. Several lines of evidence suggest that these inclusions cause neurodegeneration. Thus exploring strategies to improve neuronal survival in neurons with αSyn aggregates is critical. Previously, exposure to αSyn pre-formed fibrils (PFFs) has been shown to induce aggregation of endogenous αSyn resulting in cell death that is exacerbated by either starvation or inhibition of mTOR by rapamycin, both of which are able to induce autophagy, an intracellular protein degradation pathway. Since mTOR inhibition may also inhibit protein synthesis and starvation itself can be detrimental to neuronal survival, we investigated the effects of autophagy induction on neurons with αSyn inclusions by a starvation and mTOR-independent autophagy induction mechanism. We exposed mouse primary cortical neurons to PFFs to induce inclusion formation in the presence and absence of the disaccharide trehalose, which has been proposed to induce autophagy and stimulate lysosomal biogenesis. As expected, we observed that on exposure to PFFs, there was increased abundance of pS129-αSyn aggregates and cell death. Trehalose alone increased LC3-II levels, consistent with increased autophagosome levels that remained elevated with PFF exposure. Interestingly, trehalose alone increased cell viability over a 14-d time course. Trehalose was also able to restore cell viability to control levels, but PFFs still exhibited toxic effects on the cells. These data provide essential information regarding effects of trehalose on αSyn accumulation and neuronal survival on exposure to PFF.
帕金森病是一种使人衰弱的神经退行性疾病，其病理特征是细胞内主要由α-突触核蛋白（αSyn）组成的包涵体，这种包涵体也可在神经元之间传播。多条证据表明这些包涵体会导致神经退行性变。因此，探索改善含有αSyn聚集体的神经元存活的策略至关重要。此前研究表明，暴露于αSyn预形成纤维（PFFs）会诱导内源性αSyn聚集，导致细胞死亡，饥饿或雷帕霉素抑制mTOR都会加剧这种细胞死亡，这两种情况都能够诱导自噬，即一种细胞内蛋白质降解途径。由于抑制mTOR也可能抑制蛋白质合成，且饥饿本身可能对神经元存活有害，我们通过一种不依赖饥饿和mTOR的自噬诱导机制，研究了自噬诱导对含有αSyn包涵体的神经元的影响。我们将小鼠原代皮质神经元暴露于PFFs，在有和没有二糖海藻糖的情况下诱导包涵体形成，海藻糖被认为可诱导自噬并刺激溶酶体生物发生。正如预期的那样，我们观察到，暴露于PFFs时，pS129-αSyn聚集体的丰度增加且细胞死亡增加。单独使用海藻糖会使LC3-II水平升高，这与自噬体水平增加一致，在暴露于PFFs时自噬体水平仍保持升高。有趣的是，在14天的时间进程中，单独使用海藻糖可提高细胞活力。海藻糖还能够将细胞活力恢复到对照水平，但PFFs对细胞仍表现出毒性作用。这些数据提供了关于海藻糖对暴露于PFFs时αSyn积累和神经元存活影响的重要信息。
