Bateman David A, Chakrabartty Avijit
Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
Int J Alzheimers Dis. 2011 Feb 7;2011:962352. doi: 10.4061/2011/962352.
The amyloid peptides, Aβ40 and Aβ42, are generated through endoproteolytic cleavage of the amyloid precursor protein. Here we have developed a model to investigate the interaction of living cells with various forms of aggregated Aβ40/42. After incubation at endosomal pH 6, we observed a variety of Aβ conformations after 3 (Aβ(3)), 24 (Aβ(24)), and 90 hours (Aβ(90)). Both Aβ42(24) and Aβ40(24) were observed to rapidly bind and internalize into differentiated PC12 cells, leading to accumulation in the lysosome. In contrast, Aβ40/42(90) were both found to only weakly associate with cells, but were observed as the most aggregated using dynamic light scattering and thioflavin-T. Internalization of Aβ40/42(24) was inhibited with treatment of monodansylcadaverine, an endocytosis inhibitor. These studies indicate that the ability of Aβ40/42 to bind and internalize into living cells increases with degree of aggregation until it reaches a maximum beyond which its ability to interact with cells diminishes drastically.
淀粉样肽Aβ40和Aβ42是通过淀粉样前体蛋白的内蛋白水解切割产生的。在此，我们建立了一个模型来研究活细胞与各种形式聚集的Aβ40/42之间的相互作用。在内体pH值为6的条件下孵育后，我们在3小时（Aβ(3)）、24小时（Aβ(24)）和90小时（Aβ(90)）后观察到了多种Aβ构象。观察到Aβ42(24)和Aβ40(24)都能迅速结合并内化到分化的PC12细胞中，导致在溶酶体中积累。相比之下，发现Aβ40/42(90)与细胞的结合较弱，但使用动态光散射和硫黄素-T观察到其聚集程度最高。用内吞作用抑制剂单丹磺酰尸胺处理可抑制Aβ40/42(24)的内化。这些研究表明，Aβ40/42与活细胞结合并内化的能力随着聚集程度的增加而增强，直到达到最大值，超过该值后其与细胞相互作用的能力会急剧下降。
