Self-association and membrane binding of alpha-synuclein

描述（由申请人提供）：帕金森病是最常见的神经退行性运动障碍，估计影响1%的65岁及以上人群。蛋白质β-突触核蛋白是路易体的主要成分，路易体是帕金森病的标志性聚集蛋白质的神经元细胞质沉积物。有令人信服的证据表明，β-突触核蛋白聚集的过程与帕金森病的病理学直接相关。然而，β-突触核蛋白的聚集是一个复杂的、异质的过程，在此过程中，多种寡聚蛋白种类在不同的时间点聚集，并持续一系列的时间尺度，使其完整的表征极具挑战性。此外，在聚集过程中形成的各种分子种类与疾病病理学之间的关系仍然是一个悬而未决的问题，尽管寡聚体β-突触核蛋白与细胞膜之间的直接相互作用已经被牵连。另一个复杂的问题来自最近的两篇出版物，它们提供了证据，证明长期以来被认为是无序单体的β-突触核蛋白的天然状态实际上可能是部分结构化的四聚体。我们的假设是，AS的功能和功能失调的相互作用调制的平均构象或低聚系综和这些系综内的状态之间的动态交换的变化。我们的研究将表征这些集合在溶液中（目标1），结合到模型膜（目标2），并在活细胞（目标3），以确定与过渡到毒性状态相关的物理特征的目标。作为这些实验的结果，我们还将确定AS的假定四聚体和单体形式之间的关系。为此，我们将使用单分子和时间分辨荧光方法。我们的实验方法具有允许在有利于寡聚化或聚集的条件下表征β-突触核蛋白的优点，而不需要伴随蛋白质实际自缔合的信号解释的复杂性。我们的研究结果将是一个全面的观点，什么性质的溶液，膜，和细胞环境有利于自协会的β-突触核蛋白进入有毒结构。这种理解对于我们研究小组的长期目标至关重要，即确定潜在的分子靶点，以开发治疗或预防帕金森病的疗法。

DESCRIPTION (provided by applicant): Parkinson's disease is the most common neurodegenerative movement disorder, affecting an estimated 1% of the population aged 65 and older. The protein �-synuclein is the primary component of Lewy bodies, the neuronal cytoplasmic deposits of aggregated proteins that are the hallmark of Parkinson's disease. There is compelling evidence that the process of �-synuclein aggregation is directly related to Parkinson's disease pathology. However, the aggregation of �-synuclein is a complex, heterogeneous process during which multiple oligomeric protein species are populated at various timepoints and persist over a range of timescales, making its complete characterization extremely challenging. Moreover, the relationship between the various molecular species formed in the aggregation process and disease pathology is still an open question, although the direct interaction between oligomeric �-synuclein and cellular membranes has been implicated. An additional complication comes from two recent publications that provide evidence that the native state of �- synuclein, long believed to be a disordered monomer, may actually be a partially structured tetramer. Our hypothesis is that both the functional and dysfunctional interactions of AS are modulated by changes in the average conformational or oligomeric ensemble and the dynamic interchange between states within these ensembles. Our research will characterize these ensembles in solution (Aim 1), bound to model membranes (Aim 2), and in living cells (Aim 3), with the goal of determining physical features that are associated with th transition to toxic states. As a consequence of these experiments, we will also determine the relationship between the putative tetramer and monomer forms of AS. To do this, we will use single molecule and time- resolved fluorescence methods. Our experimental approaches have the advantage of allowing for the characterization of �-synuclein under conditions that favor oligomerization or aggregation without the complication of signal interpretation that accompanies actual self-association of the protein. The results of our investigation will be a comprehensive view of what properties of the solution, membrane, and cellular environment favor self-association of �-synuclein into toxic structures. Such understanding is critical to the long term goal of our research group to identify potential molecular targets for the development of therapeutics to treat or prevent Parkinson's disease.