MassGeneral Institute for Neurodegenerative Disease, Alzheimer Research Unit, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America.
PLoS One. 2009 Sep 4;4(9):e6906. doi: 10.1371/journal.pone.0006906.
Oligomerization and aggregation of alpha-synuclein molecules play a major role in neuronal dysfunction and loss in Parkinson's disease [1]. However, alpha-synuclein oligomerization and aggregation have mostly been detected indirectly in cells using detergent extraction methods [2], [3], [4]. A number of in vitro studies showed that dopamine can modulate the aggregation of alpha-synuclein by inhibiting the formation of or by disaggregating amyloid fibrils [5], [6], [7].
METHODOLOGY/PRINCIPAL FINDINGS: Here, we show that alpha-synuclein adopts a variety of conformations in primary neuronal cultures using fluorescence lifetime imaging microscopy (FLIM). Importantly, we found that dopamine, but not dopamine agonists, induced conformational changes in alpha-synuclein which could be prevented by blocking dopamine transport into the cell. Dopamine also induced conformational changes in alpha-synuclein expressed in neuronal cell lines, and these changes were also associated with alterations in oligomeric/aggregated species.
CONCLUSION/SIGNIFICANCE: Our results show, for the first time, a direct effect of dopamine on the conformation of alpha-synuclein in neurons, which may help explain the increased vulnerability of dopaminergic neurons in Parkinson's disease.
α-突触核蛋白分子的寡聚化和聚集在帕金森病中神经元功能障碍和丧失中起主要作用[1]。然而，α-突触核蛋白的寡聚化和聚集大多是使用去污剂提取方法在细胞中间接检测到的[2]，[3]，[4]。许多体外研究表明，多巴胺可以通过抑制淀粉样纤维的形成或解聚来调节α-突触核蛋白的聚集[5]，[6]，[7]。
方法/主要发现：在这里，我们使用荧光寿命成像显微镜（FLIM）显示α-突触核蛋白在原代神经元培养物中采用多种构象。重要的是，我们发现多巴胺而非多巴胺激动剂可诱导α-突触核蛋白的构象变化，而阻断多巴胺向细胞内转运可预防这种变化。多巴胺还诱导神经元细胞系中表达的α-突触核蛋白发生构象变化，这些变化也与寡聚/聚集物种的改变有关。
结论/意义：我们的结果首次显示多巴胺对神经元中α-突触核蛋白构象的直接影响，这可能有助于解释帕金森病中多巴胺能神经元的易感性增加。
