BioCurrents Research Center

帕金森病是第二种最常见的神经退行性疾病，其特征是进行性功能障碍， 黑质多巴胺能神经元的丧失。这一基本特征伴随着蛋白质内含物的积累， 多巴胺能神经元及其过程（路易体和神经突），其主要成分是α-突触核蛋白 （aS）。aS有7个重复序列，类似于载脂蛋白的脂质结合α-螺旋结构域， 磷脂膜显著改变其二级结构。我们最近：a）发现了aS的同源性 与脂肪酸（FA）结合蛋白（FABP）家族的结合; B）发现纯的aS可逆地结合游离的FA; c）检测到 多巴胺能细胞、正常小鼠和人脑中高度可溶的脂质相关的aS寡聚体库， 水平升高，在PD和DLB脑; d）显示暴露于多不饱和的活中脑神经元， FA增强可溶性aS低聚物的形成，并且饱和的FA延迟可溶性aS低聚物的形成;以及e）记录到增加 内源性多不饱和脂肪酸水平和膜流动性在α S-过表达的神经元，而相反的α S敲除 小鼠基于这些发现，我们假设，在水溶液中，AS通常与FA相互作用， 细胞质的膜磷脂隔室，并帮助调节脂质组成的各个方面（特别是 PUFA含量）和因此的膜性质，并且aS-FA相互作用有助于调节aS的寡聚化。 因此可以引发α 5组装成首先可溶的然后不可溶的低聚物。为了实现这个分子假说 关于aS功能和功能障碍，我们现在提出一系列相互关联的目标。1)试图证明改变 内源性PUFA水平（例如，在用A6去饱和酶抑制剂处理的细胞中降低或在小鼠模型中升高 Zellweger综合征）诱导脑细胞中内源性aS寡聚体的相应减少或增加。2）。 研究aS-FA相互作用对膜形成、超微结构和生物物理性质的影响 活细胞中的囊泡。3)为了确定PUFA-ctS相互作用是否以及如何影响一个离散的生化 迄今为止记录的aS功能：抑制磷脂酶D。我们专注于aS在脂质代谢中的关键作用 和膜囊泡的形成/稳定性来自于两个主要的 investigators.此外，最近在表达aS的酵母或酵母中进行的无偏遗传筛选强烈支持了这一点。 在果蝇中，这暗示了aS在脂质调节和膜运输中的功能。新发现 从这个赠款应该同时阐明了生理学的aS和最早的步骤，其病理 寡聚化，伴随治疗见解。

Parkinson's disease, the second most common neurodegenerative disorder, is marked by progressive dysfunction and loss of nigral dopaminergic neurons. This cardinal feature is accompanied by the accumulation of protein inclusions in dopaminergic neurons and their processes (Lewy bodies and neurites), the major constituent of which is a-synuclein (aS). aS has 7 repeats resembling the lipid-binding a-helical domains of apolipoproteins, and its bindingto phospholipid membranes markedly alters its secondary structure. We have recently: a) discovered homologies of aS with the fatty acid (FA) binding protein (FABP) family; b) found that pure aS binds free FAs reversibly; c) detected a pool of highly soluble, lipid-associated aS oligomers in dopaminergic cells, normal mouse and human brains and, at elevated levels, in PD and DLB brains; d) shown that exposure of living mesencephalic neurons to polyunsaturated FAs enhances ~ and to saturated FAs retards ~ the formation of soluble aS oligomers; and e) documented increased endogenous PUFA levels and membrane fluidity in aS-overexpressing neurons, and the opposite in aS knock-out mice. Based on these findings, we hypothesize that aS normally interacts with FAs in both the aqueous and membrane-phospholipid compartments of the cytoplasm and helps regulate aspects of lipid composition (particularly PUFA content) and thus membrane properties, and that aS-FA interactions help regulate the oligomerization of aS and can thus initiate aS assembly into first soluble and then insoluble oligomers. To pursue this molecular hypothesis about aS function and dysfunction,we now propose a series of interrelated goals. 1) To attempt to prove that altering endogenous PUFA levels (e.g., lowered in cells treated with a A6desaturase inhibitor or elevated in mice modeling Zellweger's syndrome) induces corresponding decreases or increases in endogenous aS oligomers in brain cells. 2). To examine the effects of aS-FA interactions on the formation, ultrastructure and biophysical properties of membrane vesicles in living cells. 3) To ascertain whether and how PUFA-ctS interactions affect the one discrete biochemical function of aS documented to date: inhibitingPhospholipase D. Our focus on a key role for aS in lipid metabolism and membrane vesicle formation/stability derives from a novel set of observations made by the two principal investigators. Moreover, it is strongly supported by recent unbiased genetic screens in aS-expressing yeast or Drosophila that implicated a function of aS in lipid regulation and membrane trafficking. New findingsemanating from this grant should simultaneously shed light on the physiology of aS and the earliest steps in its pathological oligomerization, with attendant therapeutic insights.