Self-assembly of Aβ1-42 into globular neurotoxins
Self-assembly of Aβ1-42 into globular neurotoxins
复制标题
DOI：
10.1021/bi030029q
复制
发表时间：
2003-11-11
期刊：
影响因子：
2.9
通讯作者：
Klein, WL
中科院分区：
文献类型：
--
作者：
Chromy, BA;Nowak, RJ;Klein, WL
淀粉样蛋白β 1-42（Abeta（1-42））是一种自缔合肽，在聚集时变得神经毒性。毒性最初归因于大的、容易形成的Abeta原纤维的存在，但现在已知多种其他有毒物质。目前的研究表明，Abeta（1-42）可以自组装成小的。无原纤维和原纤维的稳定球状集合体。通过原子力显微镜（AFM）和非变性凝胶电泳验证了大分子的缺失。变性电泳显示，球状组件包括从三聚体到24聚体的寡聚体。在4 ℃制备的低聚物保持无原纤维数天，并保持如此时，转移到37 degreesC，虽然光谱的大小转移到更大的低聚物在更高的温度。可溶性球状Abeta（1-42）寡聚体对PC 12细胞具有毒性，损害MTT还原并干扰ERK和Rac信号转导。偶尔，寡聚体既没有毒性，也没有被毒性中和抗体识别，这表明寡聚体可以呈现替代构象。寡聚化阻断活性的测试进行了斑点印迹免疫测定，并表明，银杏叶的神经保护提取物可以抑制低聚物的形成在非常低的剂量。所观察到的合成Abeta（1-42）球状组装体的神经毒性、结构和稳定性支持Abeta（1-42）寡聚体在引发阿尔茨海默病中的神经细胞功能障碍和死亡中起作用的假设。
Amyloid beta 1-42 (Abeta(1-42)) is a self-associating peptide that becomes neurotoxic upon aggregation. Toxicity originally was attributed to the presence of large, readily formed Abeta fibrils, but a variety of other toxic species are now known. The current study shows that Abeta(1-42) can self-assemble into small. stable globular assemblies free of fibrils and protofibrils. Absence of large molecules was verified by atomic force microscopy (AFM) and nondenaturing gel electrophoresis. Denaturing electrophoresis revealed that the globular assemblies comprised oligomers ranging from trimers to 24mers. Oligomers prepared at 4 degreesC stayed fibril-free for days and remained so when shifted to 37 degreesC, although the spectrum of sizes shifted toward larger oligomers at the higher temperature. The soluble, globular Abeta(1-42) oligomers were toxic to PC12 cells, impairing reduction of MTT and interfering with ERK and Rac signal transduction. Occasionally, oligomers were neither toxic nor recognized by toxicity-neutralizing antibodies, suggesting that oligomers could assume alternative conformations. Tests for oligomerization-blocking activity were carried out by dot-blot immunoassays and showed that neuroprotective extracts of Ginkgo biloba could inhibit oligomer formation at very low doses. The observed neurotoxicity, structure, and stability of synthetic Abeta(1-42) globular assemblies support the hypothesis that Abeta(1-42) oligomers play a role in triggering nerve cell dysfunction and death in Alzheimer's disease.