Heparin and other glycosaminoglycans stimulate the formation of amyloid fibrils from α-synuclein in vitro
Heparin and other glycosaminoglycans stimulate the formation of amyloid fibrils from α-synuclein in vitro
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DOI：
10.1021/bi011711s
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发表时间：
2002-02-05
期刊：
影响因子：
2.9
通讯作者：
Fink, AL
中科院分区：
文献类型：
--
作者：
Cohlberg, JA;Li, J;Fink, AL
帕金森氏病是第二种最常见的神经退行性疾病，其起因于黑质中多巴胺能神经元的丧失。α-突触核蛋白的聚集和原纤化已被认为是该疾病的致病因素。糖胺聚糖（GAGS）通常被发现与大多数淀粉样变性疾病中的淀粉样蛋白沉积相关，并且有证据支持在某些情况下GAG在淀粉样蛋白原纤维形成中的积极作用。与细胞外淀粉样蛋白沉积相反，路易体病中的α-突触核蛋白沉积是细胞内的，因此不太清楚是否涉及GAGS。为了确定糖胺聚糖的存在是否确实影响α-突触核蛋白的原纤化，在多种糖胺聚糖和其他带电聚合物的存在下研究了原纤形成的动力学。发现某些GAG（肝素、硫酸乙酰肝素）和其他高度硫酸化的聚合物（硫酸葡聚糖）显著刺激α-突触核蛋白原纤维的形成。有趣的是，GAG与α-突触核蛋白的相互作用是非常特异的，因为一些GAG，例如，硫酸角质素的作用可以忽略不计。肝素不仅增加了纤维化的速率，而且明显增加了纤维的产量。肝素与α-突触核蛋白的摩尔比和荧光素标记的肝素掺入原纤维中表明肝素整合到原纤维中，而不仅仅是原纤维化的催化剂。肝素在刺激α-突触核蛋白原纤化中的表观解离常数为0.19 μ M，表明其具有很强的亲和力。在α-突触核蛋白的A53 T和A30 P突变体中观察到肝素的类似作用。由于有一些证据表明路易体可能含有GAG，这些观察结果可能与帕金森病的病因学非常相关。
Parkinson's disease is the second most common neurodegenerative disease and results from loss of dopaminergic neurons in the substantia nigra. The aggregation and fibrillation of alpha-synuclein have been implicated as a causative factor in the disease. Glycosaminoglycans (GAGS) are routinely found associated with amyloid deposits in most amyloidosis diseases, and there is evidence to support an active role of GAGs in amyloid fibril formation in some cases. In contrast to the extracellular amyloid deposits, the alpha-synuclein deposits in Lewy body diseases are intracellular, and thus it is less clear whether GAGS may be involved. To determine whether the presence of GAGs does affect the fibrillation of alpha-synuclein, the kinetics of fibril formation were investigated in the presence of a number of GAGs and other charged polymers. Certain GAGs (heparin, heparan sulfate) and other highly sulfated polymers (dextran sulfate) were found to significantly stimulate the formation of alpha-synuclein fibrils. Interestingly, the interaction of GAGs with alpha-synuclein is quite specific, since some GAGs, e.g., keratan sulfate, had negligible effect. Heparin not only increased the rate of fibrillation but also apparently increased the yield of fibrils. The molar ratio of heparin to alpha-synuclein and the incorporation of fluorescein-labeled heparin into the fibrils demonstrate that the heparin is integrated into the fibrils and is not just a catalyst for fibrillation. The apparent dissociation constant for heparin in stimulating a-synuclein fibrillation was 0.19 muM, indicating a strong affinity. Similar effects of heparin were observed with the A53T and A30P mutants of alpha-synuclein. Since there is some evidence that Lewy bodies may contain GAGs, these observations may be very relevant in the context of the etiology of Parkinson's disease.