Trace metal contamination initiates the apparent auto-aggregation, amyloidosis, and oligomerization of Alzheimer's Aβ peptides
Trace metal contamination initiates the apparent auto-aggregation, amyloidosis, and oligomerization of Alzheimer's Aβ peptides
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DOI：
10.1007/s00775-004-0602-8
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发表时间：
2004-12-01
影响因子：
3
通讯作者：
Bush, AI
中科院分区：
文献类型：
--
作者：
Huang, XD;Atwood, CS;Bush, AI
通过疏水相互作用，核依赖蛋白聚集（“播种”）和无淀粉样蛋白纤维形成的可溶性sds抗性低聚物（“寡聚化”）是一种体外模型，被认为在阿尔茨海默病（AD）和其他淀粉样蛋白相关的神经退行性疾病中传播β -淀粉样蛋白（Abeta）沉积、积累，并引起神经毒性和突触毒性。然而，Abeta是一种高亲和力的金属蛋白，在生物金属（锌、铜和铁）存在的情况下聚集，并且在转基因小鼠中，新皮质的Abeta沉积被突触锌的遗传消融所消除。我们现在提出的体外证据表明，微量（小于或等于0.8 muM）水平的锌、铜和铁，作为实验室缓冲液和培养基中的常见污染物，是经典的Abeta1 - 42介导的播种过程和Abeta寡聚的实际引发剂。复制早期工作者的实验条件，我们发现Abeta1 - 42 （2 muM）引发的Abeta1 - 40 （20 muM）的体外沉淀和淀粉样变被微量金属污染物的螯合所消除。此外，金属螯合减少了无细胞培养基中可溶性β低聚物的形成。这些数据表明，蛋白质的自组装和寡聚化并不像以前认为的那样是自发的，金属离子在启动β淀粉样变性和寡聚化过程中可能起着强制性的作用。
Nucleation-dependent protein aggregation ("seeding'') and amyloid fibril-free formation of soluble SDS-resistant oligomers ("oligomerization'') by hydrophobic interaction is an in vitro model thought to propagate beta-amyloid (Abeta) deposition, accumulation, and incur neurotoxicity and synaptotoxicity in Alzheimer's disease (AD), and other amyloid-associated neurodegenerative diseases. However, Abeta is a high-affinity metalloprotein that aggregates in the presence of biometals ( zinc, copper, and iron), and neocortical Abeta deposition is abolished by genetic ablation of synaptic zinc in transgenic mice. We now present in vitro evidence that trace ( less than or equal to 0.8 muM) levels of zinc, copper, and iron, present as common contaminants of laboratory buffers and culture media, are the actual initiators of the classic Abeta1 - 42-mediated seeding process and Abeta oligomerization. Replicating the experimental conditions of earlier workers, we found that the in vitro precipitation and amyloidosis of Abeta1 - 40 (20 muM) initiated by Abeta1 - 42 ( 2 muM) were abolished by chelation of trace metal contaminants. Further, metal chelation attenuated formation of soluble Abeta oligomers from a cell-free culture medium. These data suggest that protein self-assembly and oligomerization are not spontaneous in this system as previously thought, and that there may be an obligatory role for metal ions in initiating Abeta amyloidosis and oligomerization.