Seeded growth of β-amyloid fibrils from Alzheimer's brain-derived fibrils produces a distinct fibril structure
Seeded growth of β-amyloid fibrils from Alzheimer's brain-derived fibrils produces a distinct fibril structure
复制标题
DOI：
10.1073/pnas.0812033106
复制
发表时间：
2009-05-05
影响因子：
11.1
通讯作者：
Tycko, Robert
中科院分区：
文献类型：
--
作者：
Paravastu, Anant K.;Qahwash, Isam;Tycko, Robert
通过固态核磁共振（NMR）对从合成的40-残基β-淀粉样蛋白（A β（1-40））肽体外制备的淀粉样蛋白原纤维的研究表明，A β（1-40）原纤维的分子结构不是唯一由氨基酸序列决定的。相反，原纤维结构取决于生长条件的精确细节。因此，在阿尔茨海默病（AD）中发展的β-淀粉样蛋白原纤维的分子结构是不确定的。我们通过硫磺素T荧光和电子显微镜证明，从已故AD患者的脑组织中提取的原纤维可用于播种合成A β（1-40）原纤维的生长，允许制备具有同位素标记的原纤维，并以足够的量进行固态NMR和其他测量。由于淀粉样蛋白结构在种子生长中自我繁殖，如先前的研究所示，脑种子合成A β（1-40）原纤维的分子结构最有可能反映AD脑中存在的结构。固态C-13核磁共振光谱的原纤维样品接种大脑材料从两个AD患者被发现几乎是相同的，表明相同的分子结构。未接种对照样品的光谱表明结构异质性更大。C-13化学位移和其他NMR数据表明，脑种子原纤维中的主要分子结构不同于先前已详细表征的纯合成A β（1-40）原纤维的结构。这些结果表明了一种新的方法，详细的结构表征淀粉样蛋白原纤维在人体组织中的发展，并在AD原纤维结构和认知功能障碍和神经退行性变的程度之间的可能的相关性的调查。
Studies by solid-state nuclear magnetic resonance (NMR) of amyloid fibrils prepared in vitro from synthetic 40-residue beta-amyloid (A beta(1-40)) peptides have shown that the molecular structure of A beta(1-40) fibrils is not uniquely determined by amino acid sequence. Instead, the fibril structure depends on the precise details of growth conditions. The molecular structures of beta-amyloid fibrils that develop in Alzheimer's disease (AD) are therefore uncertain. We demonstrate through thioflavin T fluorescence and electron microscopy that fibrils extracted from brain tissue of deceased AD patients can be used to seed the growth of synthetic A beta(1-40) fibrils, allowing preparation of fibrils with isotopic labeling and in sufficient quantities for solid-state NMR and other measurements. Because amyloid structures propagate themselves in seeded growth, as shown in previous studies, the molecular structures of brain-seeded synthetic A beta(1-40) fibrils most likely reflect structures that are present in AD brain. Solid-state C-13 NMR spectra of fibril samples seeded with brain material from two AD patients were found to be nearly identical, indicating the same molecular structures. Spectra of an unseeded control sample indicate greater structural heterogeneity. C-13 chemical shifts and other NMR data indicate that the predominant molecular structure in brain-seeded fibrils differs from the structures of purely synthetic A beta(1-40) fibrils that have been characterized in detail previously. These results demonstrate a new approach to detailed structural characterization of amyloid fibrils that develop in human tissue, and to investigations of possible correlations between fibril structure and the degree of cognitive impairment and neurodegeneration in AD.