Kisos Haya, Ben-Gedalya Tziona, Sharon Ronit
Biochemistry and Molecular Biology, IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel.
J Mol Neurosci. 2014 Feb;52(2):167-76. doi: 10.1007/s12031-013-0118-1. Epub 2013 Sep 19.
Parkinson's disease (PD) is a progressive age-dependent neurodegenerative disorder, predominantly affecting the dopamine-producing neurons residing at the substantia nigra. Abnormalities in α-synuclein (α-Syn) and dopamine transporter (DAT) are implicated in the pathogenesis of PD. We tested the hypothesis that α-Syn regulates surface DAT localization and DAT activity, in cultured cells co-expressing α-Syn and DAT, and in brains of mice modeling PD, transgenic for the mutant A53T α-Syn form. The results indicate that α-Syn expression affects the partitioning of DAT between the cell surface and intracellular compartments, resulting in lower surface DAT levels. Accordingly, lower uptake of tritiated dopamine was measured in synaptosomes of A53T α-Syn transgenic mouse brains. Importantly, we show that the effect of α-Syn on surface DAT is mediated by clathrin. Downregulation of clathrin by specific siRNAs directed against its heavy chain abolished the effect of α-Syn on phorbol 12-myristate 13-acetate-induced DAT internalization. These results suggest that α-Syn plays a role in regulating dopamine homeostasis through its involvement in clathrin-mediated endocytosis.
帕金森病（PD）是一种与年龄相关的进行性神经退行性疾病，主要影响位于黑质的多巴胺能神经元。α-突触核蛋白（α-Syn）和多巴胺转运体（DAT）的异常与PD的发病机制有关。我们在共表达α-Syn和DAT的培养细胞以及携带突变A53T α-Syn形式的转基因PD模型小鼠脑中，检验了α-Syn调节表面DAT定位和DAT活性的假说。结果表明，α-Syn的表达影响DAT在细胞表面和细胞内区室之间的分配，导致表面DAT水平降低。因此，在A53T α-Syn转基因小鼠脑的突触体中检测到氚标记多巴胺的摄取减少。重要的是，我们表明α-Syn对表面DAT的作用是由网格蛋白介导的。针对网格蛋白重链的特异性小干扰RNA（siRNA）下调网格蛋白，消除了α-Syn对佛波醇12-肉豆蔻酸酯13-乙酸酯诱导的DAT内吞作用的影响。这些结果表明，α-Syn通过参与网格蛋白介导的内吞作用在调节多巴胺稳态中发挥作用。
