Alpha-synuclein Regulates Dopamine Transporter Functions

多巴胺（DA）转运蛋白（DAT）活性的改变与帕金森病有关。错义 DAT突变与成人早发性帕金森综合征和进行性帕金森综合征直接相关。 多巴胺能神经变性增加的α-突触核蛋白，DAT的蛋白伴侣，也是 与帕金森病和其他神经退行性疾病有关。超过80%的患者 帕金森病患者会发展成痴呆症α-突触核蛋白基因在人胚肺细胞中的增殖 人参与PD和/或路易体痴呆的发展。长期 本研究的目的是确定α-突触核蛋白过表达后DAT功能障碍如何 在细胞丧失之前破坏神经元和网络功能。我们的首要目标是确定 病理学进展的潜在机制和治疗药物的鉴定 目标的帕金森病和其他疾病中DA信号功能障碍的病因学确定 神经系统疾病一直具有挑战性，因为DAT调节时空 通过调节DA传递的特征：1）释放DA的摄取，2）自发 DA神经元的放电活动和3）非囊泡DA释放（流出）。因此，关键是 首先在单个神经元上剖析这些功能的病理调节，然后确定 疾病状态下相互关联的功能变化。我们的初步和公布的数据 表明DAT和α-突触核蛋白之间存在双向相互作用，其中仅 DAT在神经元膜上的存在将α-突触核蛋白募集到膜上。我们发现 膜募集的α-突触核蛋白直接与DAT相互作用，改变DAT的离子偶联， 增加内向去极化Na+电流，抑制DAT介导的DA摄取， DA神经元中Ca 2+峰的幅度和持续时间，并导致DA增加7倍 外排导致DA再循环减少。这些有效地挑战了突触的调节， 短期的DA水平和长期的神经元完整性。我们的试点数据表明， 问题迅速扩大到细胞活动和网络功能的水平。总的来说， 这些数据支持DA神经元中α-突触核蛋白增加的总体假设 通过DAT和Ca 2+依赖性机制增加DA神经元的放电活性和DA流出 导致DA传递和神经元通讯中断。为了解决这个 假设，我们将使用分子，药理学和电生理学方法， 特别强调多巴胺的神经化学和分子机制 神经传递

Altered dopamine (DA) transporter (DAT) activity is implicated in Parkinson disease. Missense DAT mutations are directly associated with adult early-onset Parkinsonism and progressive dopaminergic neurodegeneration. Increased α-synuclein, a protein partner of DAT, is also implicated in Parkinson disease and other neurodegenerative diseases. Over 80% of patients with longstanding Parkinson disease will develop dementia. Multiplication of α-synuclein gene in human is involved in the development of PD and/or dementia with Lewy bodies. The long-term goal of this study is to determine how DAT dysfunction following α-synuclein overexpression disrupts neuronal and network function, prior to cell loss. Our primary objective is to determine the underlying mechanism/s of the progression of pathology and identification of therapeutic targets. Determining the etiology of DA signaling dysfunction in Parkinson disease and other neurological disorders have been challenging as DAT regulates the spatiotemporal characteristics of DA transmission by regulating: 1) uptake of released DA, 2) spontaneous firing activity of DA neurons and 3) non-vesicular DA release (efflux). Therefore, it is critical to first dissect the pathological regulations of these functions at a single neuron, then determine the interrelated functional changes in the diseased state. Our preliminary and published data suggest there is a bidirectional interaction between DAT and α-synuclein, where the mere existence of DAT at the neuronal membrane recruits α-synuclein to the membrane. We found membrane recruited α-synuclein directly interacts with DAT, alters the ionic coupling of DAT by increasing an inward depolarizing Na+ current, inhibits the DAT mediated DA uptake, increases the magnitude and duration of Ca2+ spikes in DA neurons and causes a 7-fold increase in DA efflux resulting in diminished DA recycling. These effectively challenge the regulation of synaptic DA levels in the short-term and neuronal integrity in the long-term. Our pilot data suggest this problem quickly scales up to the level of cellular activity and network function. Collectively, these data support the overarching hypothesis that increased α-synuclein in DA neurons increases firing activity of DA neurons and DA efflux via a DAT and Ca2+-dependent mechanism leading to disruption of DA transmission and neuronal communication. To address this hypothesis, we will use molecular, pharmacological and electrophysiological approaches with particular emphasis on neurochemical and molecular mechanisms of dopamine neurotransmission.